title: The galaxy luminosity function around groups

abstract:
  We present a study on the variations of the luminosity function of galaxies
around clusters in a numerical simulation with semi-analytic galaxies,
attempting to detect these variations in the 2dF Galaxy Redshift Survey. We
subdivide the simulation box in equal-density regions around clusters, which we
assume can be achieved by selecting objects at a given normalised distance
($r/r_{rms}$, where $r_{rms}$ is an estimate of the halo radius) from the group
centre. The semi-analytic model predicts important variations in the luminosity
function out to $r/r_{rms}\simeq5$. In brief, variations in the mass function
of haloes around clusters (large dark-matter haloes with
$M>10^{12}$h$^{-1}$M$_{\sun}$) lead to cluster central regions that present a
high abundance of bright galaxies (high $M^*$ values) as well as low luminosity
galaxies (high $\alpha$); at $r/r_{rms}\simeq 3$ there is a lack of bright
galaxies, which shows the depletion of galaxies in the regions surrounding
clusters (minimum in $M^*$ and $\alpha$), and a tendency to constant luminosity
function parameters at larger cluster-centric distances. We take into account
the observational biases present in the real data by reproducing the peculiar
velocity effect on the redshifts of galaxies in the simulation box, and also by
producing mock catalogues. We find that excluding from the analysis galaxies
wich in projection are close to the centres of the groups provides results that
are qualitatively consistent with the full simulation box results.


title: Observations of Rapid Disk-Jet Interaction in GRS 1915+105

abstract:
  We present evidence that ~ 30 minute episodes of jet formation in GRS
1915+105 may sometimes be a superposition of smaller, faster phenomena. Based
on observations in 2002 July using the Rossi X-ray Timing Explorer and the
Palomar 5 meter telescope, we show that GRS 1915+105 sometimes produces ~ 30
minute infrared flares that can entirely be explained as a combination of small
(~ 150 second) flares, one for each oscillation in the accompanying X-ray light
curve. We discuss the differences between these observations and similar ones
in 1997 August and conclude that an X-ray "trigger spike" seen during each
cycle in 1997 is a key ingredient for large ejections to occur on ~ 30 minute
timescales in this source.


title: HST/ACS Images of the GG Tauri Circumbinary Disk

abstract:
  Hubble Space Telescope Advanced Camera for Surveys images of the young binary
GG Tauri and its circumbinary disk in V and I bandpasses were obtained in 2002
and are the most detailed of this system to date. The confirm features
previously seen in the disk including: a "gap" apparently caused by shadowing
from circumstellar material; an asymmetrical distribution of light about the
line of sight on the near edge of the disk; enhanced brightness along the near
edge of the disk due to forward scattering; and a compact reflection nebula
near the secondary star. New features are seen in the ACS images: two short
filaments along the disk; localized but strong variations in disk intensity
("gaplets"); and a "spur" or filament extending from the reflection nebulosity
near the secondary. The back side of the disk is detected in the V band for the
first time. The disk appears redder than the combined light from the stars,
which may be explained by a varied distribution of grain sizes. The brightness
asymmetries along the disk suggest that it is asymmetrically illuminated by the
stars due to extinction by nonuniform circumstellar material or the illuminated
surface of the disk is warped by tidal effects (or perhaps both). Localized,
time-dependent brightness variations in the disk are also seen.


title:
Energetics of the superflare from SGR1806-20 an a possible associated
  gravitational wave burst

abstract:
  We discuss in this Letter the energetics of large gamma-ray superflares
observed from Soft-Gamma Repeater sources. The last recorded event has in fact
ruled out some models for the energy release. For the first time actual
information about a possible associated gravitational wave emission may be
gathered from the LIGO data, even in the case that most of the energy was
emitted in gamma-rays. Even upper limits on the amplitude of the latter $h$ at
the expected frequency $f_{c} \leq 2 kHz$ may be useful to further constrain
the remaining mechanisms


title: Binary Mergers and Growth of Black Holes in Dense Star Clusters

abstract:
  We model the dynamical evolution of primordial black holes (BHs) in dense
star clusters using a simplified treatment of stellar dynamics in which the BHs
are assumed to remain concentrated in an inner core, completely decoupled from
the background stars. Dynamical interactions involving BH binaries are computed
exactly and are generated according to a Monte Carlo prescription. Recoil and
ejections lead to complete evaporation of the BH core on a timescale ~10^9 yr
for typical globular cluster parameters. Orbital decay driven by gravitational
radiation can make binaries merge and, in some cases, successive mergers can
lead to significant BH growth. Our highly simplified treatment of the cluster
dynamics allows us to study a large number of models and to compute statistical
distributions of outcomes, such as the probability of massive BH growth and
retention in a cluster. We find that, in most models, there is a significant
probability (~20-80%) of BH growth with final masses > 100 M_{\sun}. In one
case, a final BH formed with mass ~ 620 M_{\sun}. However, if the typical
merger recoil speed (due to asymmetric emission of gravitational radiation)
significantly exceeds the cluster escape speed, no growth ever occurs.
Independent of the recoil speed, we find that BH-BH mergers enhanced by
dynamical interactions in cluster cores present an important source of
gravitational waves for ground--based laser interferometers. Under optimistic
conditions, the total rate of detections by Advanced LIGO, could be as high as
a few tens of events per year from inspiraling BHs from clusters.


title: Relativistic outflow in CXO CDFS J033260.0-274748

abstract:
  In this letter we report the detection of a strong and extremely blueshifted
X-ray absorption feature in the 1 Ms Chandra spectrum of CXO CDFS
J033260.0-274748, a quasar at z = 2.579 with L_2-10keV ~ 4x10^44 ergs/s. The
broad absorption feature at ~ 6.3 keV in the observed frame can be fitted
either as an absorption edge at 20.9 keV or as a broad absorption line at 22.2
keV rest frame. The absorber has to be extremely ionized with an ionization
parameter \xi ~ 10^4, and a high column density N_H >5x10^23 cm^-2. We reject
the possibility of a statistical or instrumental artifact. The most likely
interpretation is an extremely blueshifted broad absorption line or absorption
edge, due to H or He--like iron in a relativistic jet-like outflow with bulk
velocity of ~ 0.7-0.8 c. Similar relativistic outflows have been reported in
the X-ray spectra of several other AGNs in the past few years.


title:
The Shape of Galaxy Cluster Dark Matter Haloes: Systematics of Its
  Imprint on Cluster Gas, and Comparison to Observations

abstract:
  (Abridged) We study predictions for galaxy cluster observables that can test
the statistics of dark matter halo shapes expected in a flat LCDM universe. We
present a simple analytical model for the prediction of cluster-scale X-ray
observations, approximating clusters as isothermal systems in hydrostatic
equilibrium, and dark matter haloes as ellipsoids with uniform axial ratios. We
test the model against high-resolution, hydrodynamic cluster simulations to
gauge its reliability. We find that this simple prescription does a good job of
predicting the distribution of cluster X-ray ellipticities compared to the
simulations as long as one focuses on cluster regions that are less sensitive
to recent mergers. Based on this simple model, the distribution of cluster-size
halo shapes expected in the concordance LCDM cosmology implies an X-ray
ellipticity distribution with a mean of 0.32 +- 0.01 and a scatter of 0.14 +-
0.01 for the mass range (1-4)x10^{14} Msun/h. We find it important to include
the mass dependence of halo shape to make comparisons to observational samples
that contain many, very massive clusters. We analyse the systematics of four
observational samples of cluster ellipticities and find that our results are
statistically compatible with observations. In particular, we find remarkably
good agreement between two recent ROSAT samples and LCDM predictions that DO
NOT include gas cooling. We also test how well our analytical model can predict
Sunyaev-Zel'dovich decrement maps and find that it is less successful although
still useful; the model does not perform as well as a function of flux level in
this case because of the changing triaxiality of dark matter haloes as a
function of radial distance. Both this effect and the changing alignment of
isodensity shells of dark matter haloes leave an imprint on cluster gas...


title: Photometric redshift of the GRB 981226 host galaxy

abstract:
  No optical afterglow was found for the dark burst GRB 981226 and hence no
absorption redshift has been obtained. We here use ground-based and space
imaging observations to analyse the spectral energy distribution (SED) of the
host galaxy. By comparison with synthetic template spectra we determine the
photometric redshift of the GRB 981226 host to be z_phot = 1.11+/-0.06 (68%
confidence level). While the age-metallicity degeneracy for the host SED
complicates the determination of accurate ages, metallicity, and extinction,
the photometric redshift is robust. The inferred z_phot value is also robust
compared to a Bayesian redshift estimator which gives z_phot=0.94+/-0.13. The
characteristics for this host are similar to other GRB hosts previously
examined. Available low resolution spectra show no emission lines at the
expected wavelengths. The photometric redshift estimate indicates an isotropic
energy release consistent with the Amati relation for this GRB which had a
spectrum characteristic of an X-ray flash.


title:
A dark jet dominates the power output of the stellar black hole Cygnus
  X-1

abstract:
  Accreting black holes are thought to emit the bulk of their power in the
X-ray band by releasing the gravitational potential energy of the infalling
matter. At the same time, they are capable of producing highly collimated jets
of energy and particles flowing out of the system with relativistic velocities.
Here we show that the 10 solar mass black hole in the X-ray binary Cygnus X-1
is surrounded by a large-scale (about 5 pc in diameter) ring-like structure
that appears to be inflated by the inner radio jet. We estimate that in order
to sustain the observed emission of the ring, the jet of Cygnus X-1 has to
carry a kinetic power that can be as high as the bolometric X-ray luminosity of
the binary system. This result may imply that low-luminosity stellar mass black
holes as a whole dissipate the bulk of the liberated accretion power in the
form of `dark', radiatively inefficient relativistic outflows, rather than
locally in the X-ray emitting inflow.


title:
A possible line-like emission feature at 8 keV in the Seyfert 1.2 UGC
  3973

abstract:
  Two short X-ray exposures (< 3600 s each) of the radio-quiet Seyfert 1.2
galaxy UGC 3973 (Mrk 79) were conducted with XMM-Newton as part of an AGN
snap-shot survey. In this paper we concentrate on the significance and possible
origin of a narrow 8 keV (rest-frame) line-like emission feature detected with
the pn instrument during the second observation. Simulations show that the
feature is significant at 96.0-98.4% confidence, depending on what a priori
assumptions are made. The feature cannot be attributed to background
contamination and appears to be variable (or transient) since it was not
detected in the first observation of UGC 3973 six months earlier. However, a
constant feature cannot be completely dismissed, based on the 90% upper-limit
on the flux from the first observation. There is some indication that the
feature is variable over the duration of the second observation as well. We
discuss various models (e.g. Ni emission, recombination edges, outflows, disc
lines) which could potentially produce an emission feature at such energies.


title:
Multiple relativistic outbursts of GRS 1915+105: radio emission and
  internal shocks

abstract:
  We present 5-GHz MERLIN radio images of the microquasar GRS 1915+105 during
two separate outbursts in 2001 March and 2001 July, following the evolution of
the jet components as they move outwards from the core of the system. Proper
motions constrain the intrinsic jet speed to be >0.57c, but the uncertainty in
the source distance prevents an accurate determination of the jet speed. No
deceleration is observed in the jet components out to an angular separation of
about 300mas. Linear polarisation is observed in the approaching jet component,
with a gradual rotation in position angle and a decreasing fractional
polarisation with time. Our data lend support to the internal shock model
whereby the jet velocity increases leading to internal shocks in the
pre-existing outflow before the jet switches off. The compact nuclear jet is
seen to re-establish itself within two days, and is visible as core emission at
all epochs. The energetics of the source are calculated for the possible range
of distances; a minimum power of 1-10 per cent of the Eddington luminosity is
required to launch the jet.


title: Simulations of magnetic fields in filaments

abstract:
  The intergalactic magnetic field within filaments should be less polluted by
magnetised outflows from active galaxies than magnetic fields in clusters.
Therefore, filaments may be a better laboratory to study magnetic field
amplification by structure formation than galaxy clusters which typically host
many more active galaxies. We present highly resolved cosmological AMR
simulations of magnetic fields in the cosmos and make predictions about the
evolution and structure of magnetic fields in filaments. Comparing our results
to observational evidence for magnetic fields in filaments suggests that
amplification of seed fields by gravitational collapse is not sufficient to
produce IGM fields. Finally, implications for cosmic ray transport are
discussed.


title: Local Galaxies as Damped Ly-Alpha Analogs

abstract:
  We calculate in detail the expected properties of low redshift DLA systems
under the assumption that they arise in the gaseous disks of galaxies like
those in the z=0 population. A sample of 355 nearby galaxies is analysed, for
which high quality HI 21-cm emission line maps are available as part of an
extensive survey with the Westerbork telescope (WHISP). We find that expected
luminosities, impact parameters between quasars and DLA host galaxies, and
metal abundances are in good agreement with the observed properties of DLAs and
DLA galaxies. The measured redshift number density of z=0 gas above the DLA
limit is dN/dz=0.045 +/- 0.006, which compared to higher redshift measurements
implies that there is no evolution in the comoving density of DLAs along a line
of sight between z=1.5 and z=0, and a decrease of only a factor of two from z=4
to the present time. We conclude that the local galaxy population can explain
all properties of low redshift DLAs.


title: Period Changes in Ultra-compact Double White Dwarfs

abstract:
  In recent years there has been much interest in the nature of two stars, V407
Vul and RXJ0806+1527, which are widely thought to be binary white dwarfs of
very short orbital period, 570 and 321 seconds respectively. As such they
should be strong sources of gravitational waves and possible ancestors of the
accreting AM CVn stars. Monitoring at X-ray and optical wavelengths has
established that the period of each star is decreasing, at rates compatible
with that expected from gravitational radiation. This has been taken to support
the ``unipolar inductor'' model in which the white dwarfs are detached and the
X-rays produced by the dissipation of magnetically-induced electric currents.
In this paper we show that this interpretation is incorrect because it ignores
associated torques which transfer angular momentum between the spin of the
magnetic white dwarf and the orbit. We show that this torque is 10^5 times
larger than the GR term in the case of V407 Vul, and 10 times larger for
RXJ0806+1527. For V407 Vul, the unipolar inductor model can only survive if the
white dwarf spins 100 times faster than the orbit. Since this could only come
about through accretion, the validity of the unipolar inductor appears
questionable for this star. We also consider whether accretion models can fit
the observed spin-up, concluding that they can, provided that a mechanism
exists for driving the mass transfer rate away from its equilibrium value.


title: Structure and scaling of the entropy in nearby galaxy clusters

abstract:
  Using XMM-Newton observations, we investigate the scaling and structural
properties of the ICM entropy in a sample of 10 nearby (z < 0.2) relaxed galaxy
clusters in the temperature range 2-9 keV. We derive the local
entropy-temperature (S-T) relation at R = 0.1, 0.2, 0.3 and 0.5 R_200. The
logarithmic slope of the relation is the same within the 1\sigma error at all
scaled radii. However, the intrinsic dispersion about the best fitting relation
is significantly higher at 0.1 R_200. The slope is 0.64\pm0.11 at 0.3 R_200, in
excellent agreement with previous work. We also investigate the entropy-mass
relation at density contrasts \delta=5000, 2500 and 1000. We find a shallower
slope than that expected in simple self-similar models, which is in agreement
with the observed empirically-determined entropy-temperature and
mass-temperature scaling. The dispersion is smaller than for the S-T relation.
Once scaled appropriately, the entropy profiles appear similar beyond ~0.1
R_200, with an intrinsic dispersion of ~15 per cent and a shape consistent with
gravitational heating (S(r) \propsim r^{1.1}). However, the scatter in scaled
entropy profiles increases with smaller scaled radius, to more than 60 per cent
at R \lesssim 0.05 R_200. Our results are in qualitative agreement with models
which boost entropy production at the accretion shock. However, localised
entropy modification may be needed to explain the dispersion in the inner
regions.


title: Crab: the standard X-ray candle with all (modern) X-ray satellites

abstract:
  Various X-ray satellites have used the Crab as a standard candle to perform
their calibrations in the past. The calibration of XMM-Newton, however, is
independent of the Crab nebula, because this object has not been used to adjust
spectral calibration issues. In 2004 a number of special observations were
performed to measure the spectral parameters and the absolute flux of the Crab
with XMM-Newtons EPIC-pn CCD camera. We describe the results of the campaign in
detail and compare them with data of four current missions (Integral, Swift,
Chandra, RXTE) and numerous previous missions (ROSAT, EXOSAT, Beppo-SAX, ASCA,
Ginga, Einstein, Mir-HEXE).


title: VHE gamma ray absorption by galactic interstellar radiation field

abstract:
  Adopting a recent calculation of the Galactic interstellar radiation field,
we calculate the attenuation of the very high energy gamma rays from the
Galactic sources. The infra-red radiation background near the Galactic Center
is very intense due to the new calculation and our result shows that a cutoff
of high energy gamma ray spectrum begins at about 20 TeV and reaches about 10%
for 50 TeV gamma rays.


title: Gas and dust properties in the afterglow spectra of GRB 050730

abstract:
  We present early WHT ISIS optical spectroscopy of the afterglow of gamma-ray
burst GRB 050730. The spectrum shows a DLA system with the highest measured
hydrogen column to date: N(HI) = 22.1 +/- 0.1 at the third-highest GRB redshift
z = 3.968. Our analysis of the Swift XRT X-ray observations of the early
afterglow show X-ray flares accompanied by decreasing X-ray absorption. From
both the optical and the X-ray spectra we constrain the dust and gas properties
of the host galaxy. We find the host to be a low metallicity galaxy, with low
dust content. Much of the X-ray absorbing gas is situated close to the GRB,
whilst the HI absorption causing the DLA is most likely located further out.


title: Diffuse radio emission in a REFLEX cluster

abstract:
  Deep Very Large Array radio observations are presented for the REFLEX
clusters RXCJ0437.1+0043 and RXCJ1314.4-2515. They are at similar distance and
show similar X-ray luminosity, but they are quite different in X-ray structure.
Indeed RXCJ0437.1+0043 is regular and relaxed, whereas RXCJ1314.4-2515 is
characterized by substructure and possible merging processes. The radio images
reveal no diffuse emission in RXCJ0437.1+0043, and a complex diffuse structure
in RXCJ1314.4-2515. The diffuse source in the latter cluster consists of a
central radio halo which extends to the West toward the cluster periphery and
bends to the North to form a possible relic. Another extended source is
detected in the eastern cluster peripheral region. Although there could be
plausible optical identifications for this source, it might also be a relic
candidate owing to its very steep spectrum. The present results confirm the
tight link between diffuse cluster radio sources and cluster merger processes.


title:
Near-Infrared Spectroscopy of 0.4<z<1.0 CFRS Galaxies: Oxygen
  Abundances, SFRs and Dust

abstract:
  Using new J-band VLT-ISAAC and Keck-NIRSPEC spectroscopy, we have measured
Halpha and [NII] line fluxes for 0.47<z<0.92 CFRS galaxies which have [OII],
Hbeta and [OIII]a line fluxes available from optical spectroscopy, to
investigate how the properties of the star forming gas in galaxies evolve with
redshift. We derive the extinction and oxygen abundances for the sample using a
method based on a set of ionisation parameter and oxygen abundance diagnostics,
simultaneously fitting the [OII], Hbeta,[OIII], Halpha, and [NII] line fluxes.
The individual reddening measurements allow us to accurately correct the
Halpha-based star formation rate (SFR) estimates for extinction. Our most
salient conclusions are: a) in all 30 CFRS galaxies the source of gas
ionisation is not due to AGN activity; b) we find a range of 0<AV<3, suggesting
that it is important to determine the extinction for every single galaxy in
order to reliably measure SFRs and oxygen abundances in high redshift galaxies;
c) high values of [NII]/Halpha >0.1 for most (but not all) of the CFRS galaxies
indicate that they lie on the high-metallicity branch of the R23 calibration;
d) about one third of the 0.47<z<0.92 CFRS galaxies in our sample have lower
metallicities than local galaxies with similar luminosities and star formation
rates; e) comparison with a chemical evolution model indicates that these low
metallicity galaxies are unlikely to be the progenitors of metal-poor dwarf
galaxies at z~0.


title:
Chandra observation of the fast X-ray transient IGR J17544-2619:
  evidence for a neutron star?

abstract:
  IGR J17544-2619 belongs to a distinct group of at least seven fast X-ray
transients that cannot readily be associated with nearby flare stars or
pre-main sequence stars and most probably are X-ray binaries with wind
accretion. Sofar, the nature of the accretor has been determined in only one
case (SAX J1819.3-2525/V4641 Sgr). We carried out a 20 ks Chandra ACIS-S
observation of IGR J17544-2619 which shows the source in quiescence going into
outburst. The Chandra position confirms the previous tentative identification
of the optical counterpart, a blue O9Ib supergiant at 3 to 4 kpc (Pellizza,
Chaty & Negueruela, in prep.). This is the first detection of a fast X-ray
transient in quiescence. The quiescent spectrum is very soft. The photon index
of 5.9+/-1.2 (90% confidence error margin) is much softer than 6 quiescent
black hole candidates that were observed with Chandra ACIS-S (Kong et al. 2002;
Tomsick et al. 2003). Assuming that a significant fraction of the quiescent
photons comes from the accretor and not the donor star, we infer that the
accretor probably is a neutron star. A fit to the quiescent spectrum of the
neutron star atmosphere model developed by Pavlov et al. (1992) and Zavlin et
al. (1996) implies an unabsorbed quiescent 0.5--10 keV luminosity of
(5.2+/-1.3) x 10^32 erg/s. We speculate on the nature of the brief outbursts.


title: Health and cleanliness of the XMM-Newton science payload since launch

abstract:
  On December 10th 2004 the XMM-Newton observatory celebrated its 5th year in
orbit. Since the beginning of the mission steady health and contamination
monitoring has been performed by the XMM-Newton SOC and the instrument teams.
Main targets of the monitoring, using scientific data for all instruments on
board, are the behaviour of the Charge Transfer Efficiency, the gain, the
effective area and the bad, hot and noisy pixels. The monitoring is performed
by combination of calibration observations using internal radioactive
calibration sources with observations of astronomical targets. In addition a
set of housekeeping parameters is continuously monitored reflecting the health
situation of the instruments from an engineering point of view. We show trend
behaviour over the 5 years especially in combination with events like solar
flares and other events affecting the performance of the instruments.


title:
Evolution of rapidly rotating metal-poor massive stars towards gamma-ray
  bursts

abstract:
  Recent models of rotating massive stars including magnetic fields prove it
difficult for the cores of single stars to retain enough angular momentum to
produce a collapsar and gamma-ray burst. At low metallicity, even very massive
stars may retain a massive hydrogen envelope due to the weakness of the stellar
winds, posing an additional obstacle to the collapsar model. Here, we consider
the evolution of massive, magnetic stars where rapid rotation induces almost
chemically homogeneous evolution. We find that in this case, the requirements
of the collapsar model are rather easily fulfilled if the metallicity
sufficiently small: 1) Rapidly rotating helium stars are formed without the
need to remove the hydrogen envelope, avoiding mass-loss induced spin-down. 2)
Angular momentum transport from the helium core to hydrogen envelope by
magnetic torques is insignificant. We demonstrate this by calculating
evolutionary models of massive stars with various metallicities, and derive an
upper metallicity limit for this scenario based on currently proposed mass loss
rates. Our models also suggest the existence of a lower CO-core mass limit of
about 10 Msun -- which relates to an initial mass of only about 20 Msun within
our scenario -- for GRB production. We argue that the relative importance of
the considered GRB progenitor channel, compared to any channel related to
binary stars, may increase with decreasing metallicity, and that this channel
might be the major path to GRBs from first stars.


title:
Chandra X-ray Observation of a Mature Cloud-Shock Interaction in the
  Bright Eastern Knot Region of Puppis A

abstract:
  We present Chandra X-ray images and spectra of the most prominent cloud-shock
interaction region in the Puppis A supernova remnant. The Bright Eastern Knot
(BEK) has two main morphological components: (1) a bright compact knot that
lies directly behind the apex of an indentation in the eastern X-ray boundary
and (2) lying 1' westward behind the shock, a curved vertical structure (bar)
that is separated from a smaller bright cloud (cap) by faint diffuse emission.
Based on hardness images and spectra, we identify the bar and cap as a single
shocked interstellar cloud. Its morphology strongly resembles the ``voided
sphere'' structures seen at late times in Klein et al.'s experimental
simulations of cloud-shock interactions, when the crushing of the cloud by
shear instabilities is well underway. We infer an interaction time of roughly 3
cloud-crushing timescales, which translates to 2000-4000 years, based on the
X-ray temperature, physical size, and estimated expansion of the shocked cloud.
This is the first X-ray identified example of a cloud-shock interaction in this
advanced phase. Closer to the shock front, the X-ray emission of the compact
knot in the eastern part of the BEK region implies a recent interaction with
relatively denser gas, some of which lies in front of the remnant. The complex
spatial relationship of the X-ray emission of the compact knot to optical [O
III] emission suggests that there are multiple cloud interactions occurring
along the line of sight.


title:
The MAGIC Project: Contributions to ICRC 2005, Pune, India, Part 1:
  Observations

abstract: The MAGIC contributions to ICRC 2005: Observational results (7 contributions)


title: A New Large-Well 1024x1024 Si:As Detector for the Mid-Infrare

abstract:
  We present a description of a new 1024x1024 Si:As array designed for
ground-based use from 5 - 28 microns. With a maximum well depth of 5e6
electrons, this device brings large-format array technology to bear on
ground-based mid-infrared programs, allowing entry to the megapixel realm
previously only accessible to the near-IR. The multiplexer design features
switchable gain, a 256x256 windowing mode for extremely bright sources, and it
is two-edge buttable. The device is currently in its final design phase at DRS
in Cypress, CA. We anticipate completion of the foundry run in the beginning of
2006. This new array will enable wide field, high angular resolution
ground-based follow up of targets found by space-based missions such as the
Spitzer Space Telescope and the Widefield Infrared Survey Explorer (WISE).


title: Preliminary Design of The Wide-Field Infrared Survey Explorer (WISE)

abstract:
  The Wide-field Infrared Survey Explorer (WISE), a NASA MIDEX mission, will
survey the entire sky in four bands from 3.3 to 23 microns with a sensitivity
1000 times greater than the IRAS survey. The WISE survey will extend the Two
Micron All Sky Survey into the thermal infrared and will provide an important
catalog for the James Webb Space Telescope. Using 1024x1024 HgCdTe and Si:As
arrays at 3.3, 4.7, 12 and 23 microns, WISE will find the most luminous
galaxies in the universe, the closest stars to the Sun, and it will detect most
of the main belt asteroids larger than 3 km. The single WISE instrument
consists of a 40 cm diamond-turned aluminum afocal telescope, a two-stage solid
hydrogen cryostat, a scan mirror mechanism, and reimaging optics giving 5"
resolution (full-width-half-maximum). The use of dichroics and beamsplitters
allows four color images of a 47'x47' field of view to be taken every 8.8
seconds, synchronized with the orbital motion to provide total sky coverage
with overlap between revolutions. WISE will be placed into a Sun-synchronous
polar orbit on a Delta 7320-10 launch vehicle. The WISE survey approach is
simple and efficient. The three-axis-stabilized spacecraft rotates at a
constant rate while the scan mirror freezes the telescope line of sight during
each exposure. WISE is currently in its Preliminary Design Phase, with the
mission Preliminary Design Review scheduled for July, 2005. WISE is scheduled
to launch in mid 2009; the project web site can be found at
www.wise.ssl.berkeley.edu.


title: Absolute Proper Motion of the Canis Major Dwarf Galaxy Candidate

abstract:
  We have measured the absolute proper motion of the candidate Canis Major
dwarf galaxy (CMa) at $(l,b) = (240\arcdeg, -8\arcdeg)$. Likely main-sequence
stars in CMa have been selected from a region in the color-magnitude diagram
that has very little contamination from known Milky Way components. We obtain
$\mu_{l} cos b = -1.47 \pm 0.37$ and $\mu_{b} = -1.07 \pm 0.38$ mas yr$^{-1}$,
on the ICRS system via Hipparcos stars. Together with the radial velocity of
109 km s$^{-1}$, and the assumed distance of 8 kpc, these results imply a space
motion of $(\Pi, \Theta, W) = (-5 \pm 12, 188 \pm 10, -49 \pm 15)$ km s$^{-1}$.
While CMa has in-plane rotation similar to the mean of thick disk stars, it
shows significant $(3\sigma)$ motion perpendicular to the disk, and differs
even more $(7\sigma)$ from that expected for the Galactic warp. The $W$
velocity lends support to the argument that the CMa overdensity is part of a
satellite galaxy remnant.


title: On Heating of Cluster Cooling Flows by Sound Waves

abstract:
  We investigate heating of the cool core of a galaxy cluster through the
dissipation of sound waves excited by the activities of the central active
galactic nucleus (AGN). Using a weak shock theory, we show that this heating
mechanism alone cannot reproduce observed temperature and density profiles of a
cluster, because the dissipation length of the waves is much smaller than the
size of the core and thus the wave energy is not distributed to the whole core.
However, we find that if it is combined with thermal conduction from the hot
outer layer of the cluster, the wave heating can reproduce the observational
results.


title: A Simple Measurement of Turbulence in Cores of Galaxy Clusters

abstract:
  Using a simple model, we study the effects of turbulence on the motion of
bubbles produced by AGN jet activities in the core of a galaxy cluster. We
focus on the turbulence with scales larger then the size of the bubbles. We
show that for a bubble pair with an age of ~10^8 yr, the projected angle
between the two vectors from the cluster center to the two bubbles should be ~>
90 degree and the ratio of their projected distances from the cluster center
should be ~< 2.5, if the velocity and scale of the turbulence are ~250 km s^-1
and ~20 kpc, respectively. The positions of the bubbles observed in the Perseus
cluster suggest that the turbulent velocity is ~>100 km s^-1 for the cluster.


title:
The DEEP2 Galaxy Redshift Survey: The Evolution of Void Statistics from
  z~1 to z~0

abstract:
  We present measurements of the void probability function (VPF) at z~1 using
data from the DEEP2 Redshift Survey and its evolution to z~0 using data from
the Sloan Digital Sky Survey (SDSS). We measure the VPF as a function of galaxy
color and luminosity in both surveys and find that it mimics trends displayed
in the two-point correlation function, $\xi$; namely that samples of brighter,
red galaxies have larger voids (i.e. are more strongly clustered) than fainter,
blue galaxies. We also clearly detect evolution in the VPF with cosmic time,
with voids being larger in comoving units at z~0. We find that the reduced VPF
matches the predictions of a `negative binomial' model for galaxies of all
colors, luminosities, and redshifts studied. This model lacks a physical
motivation, but produces a simple analytic prediction for sources of any number
density and integrated two-point correlation function, \bar{\xi}. This implies
that differences in the VPF across different galaxy populations are consistent
with being due entirely to differences in the population number density and
\bar{\xi}. The robust result that all galaxy populations follow the negative
binomial model appears to be due to primarily to the clustering of dark matter
halos. The reduced VPF is insensitive to changes in the parameters of the halo
occupation distribution, in the sense that halo models with the same \bar{\xi}
will produce the same VPF. For the wide range of galaxies studied, the VPF
therefore does not appear to provide useful constraints on galaxy evolution
models that cannot be gleaned from studies of \bar{\xi} alone. (abridged)


title:
An Intermediate-Mass Black Hole in the Globular Cluster G1: Improved
  Significance from New Keck and Hubble Space Telescope Observations

abstract:
  We present dynamical models for the massive globular cluster G1. The goal is
to measure or place a significant upper limit on the mass of any central black
hole. Whether or not globular clusters contain central massive black holes has
important consequences for a variety of studies. We use new kinematic data
obtained with Keck and new photometry from the Hubble Space Telescope. The Keck
spectra allow us to obtain kinematics out to large radii that are required to
pin down the mass-to-light ratio of the dynamical model and the orbital
structure. The Hubble Space Telescope observations give us a factor of two
better spatial resolution for the surface brightness profile. By fitting
non-parametric, spherical, isotropic models we find a best-fit black hole mass
of 1.7(+-0.3)e4 Msun. Fully general axisymmetric orbit-based models give
similar results, with a black hole mass of 1.8(+-0.5)e4 Msun. The no-black hole
model has Delta_chi^2=5 (marginalized over mass-to-light ratio), implying less
than 3% significance. We have taken into account any change in the
mass-to-light ratio in the center due to stellar remnants. These results are
consistent with our previous estimate in Gebhardt, Rich & Ho (2002), and
inconsistent with the analysis of Baumgardt et al. (2003) who claim that G1
does not show evidence for a black hole. These new results make G1 the best
example of a cluster that contains an intermediate-mass black hole.


title:
Optimal Extraction of Cosmological Information from Supernova Data in
  the Presence of Calibration Uncertainties

abstract:
  We present a new technique to extract the cosmological information from
high-redshift supernova data in the presence of calibration errors and
extinction due to dust. While in the traditional technique the distance modulus
of each supernova is determined separately, in our approach we determine all
distance moduli at once, in a process that achieves a significant degree of
self-calibration. The result is a much reduced sensitivity of the cosmological
parameters to the calibration uncertainties. As an example, for a strawman
mission similar to that outlined in the SNAP satellite proposal, the increased
precision obtained with the new approach is roughly equivalent to a factor of
five decrease in the calibration uncertainty.


title:
The Atmospheric Cherenkov Imaging Technique for Very High Energy
  Gamma-ray Astronomy

abstract:
  The Atmospheric Cherenkov Imaging Technique has opened up the gamma-ray
spectrumfrom 100 GeV to 50 TeV to astrophysical exploration. The development of
the technique is described as are the basic principles underlying its use. The
current generation of arrays of telescopes is briefly described and the early
results are summarized.


title: The Reddening of Red Supergiants: When Smoke Gets In Your Eyes

abstract:
  Deriving the physical properties of red supergiants (RSGs) depends upon
accurate corrections for reddening by dust. We use our recent modeling of the
optical spectra of RSGs to address this topic. We find: (1) Previous broad-band
studies have underestimated the correction for extinction in the visible, and
hence the luminousities, if derived from V. (2) A significant fraction of RSGs
in Galactic OB associations and clusters show up to several magnitudes of
excess visual extinction compared to OB stars in the same regions; we argue
that this is likely due to circumstellar dust around the RSGs. (3) RSGs
contribute dust grains at the rate of $3 \times 10^{-8} M_\odot$ yr$^{-1}$
kpc$^{-2}$ in the solar neighborhood, comparable to what we estimate for
late-type WC Wolf-Rayet stars, $1 \times 10^{-7} M_\odot$ yr$^{-1}$ kpc$^{-2}$.
In the solar neighborhood this represents only a few percent of the dust
production (which is dominated by low-mass AGBs), but we note that in
low-metallicity starbursts, dust production by RSGs would likely dominate over
other sources.


title:
HS 2134+0400 - new very metal-poor galaxy, a representative of void
  population?

abstract:
  We present the SAO 6m telescope spectroscopy of a blue compact galaxy (BCG)
HS 2134+0400 discovered in frame of the dedicated Hamburg/SAO survey for Low
Metallicity BCGs (HSS-LM). Its very low abundance of oxygen (12+log(O/H) =
7.44), as well as other heavy elements (S, N, Ne, Ar), assigns this dwarf
galaxy to the group of BCGs with the lowest metal content. There are only eight
that low metallicity among several thousand known BCGs in the nearby Universe.
The abundance ratios for the heavy elements (S/O, Ne/O, N/O, and Ar/O) are well
consistent with the typical values of other very metal-poor BCGs. The global
environment of HS 2134+0400 is atypical of the majority of BCGs. The object
falls within the Pegasus void, the large volume with the very low density of
galaxies with the normal (M_B* = -19.6) or high luminosity. Since we found in
voids a dozen more the very metal-poor galaxies, we discuss the hypothesis that
such objects can be representative of a substantial fraction of the void dwarf
galaxy population.


title: Discovery of deuterated water in a young proto-planetary disk

abstract:
  We report the first detection of the ground transition of the deuterated
water at 464 GHz in the young proto-planetary disk surrounding the solar type
protostar DM Tau. The line is observed in absorption against the continuum from
the cold dust in the disk midplane, with a line to continuum ratio close to
unity. The observation implies that deuterated gaseous water is present, with a
relatively large abundance ($\sim 3\times10^{-9}$), in the outer disk above the
midplane, where the density is, within a factor ten, $\sim 10^6$ cm$^{-3}$ and
the temperature is lower than about 25 K. In these conditions, the H$_2$O
condensation timescale is much smaller than the DM Tau disk age, and,
therefore, water should be fully frozen onto the grain mantles. We suggest that
UV photons and/or X-rays sublimate part of the mantles re-injecting the ices
into the gas phase. Even though there is currently no measurement of H$_2$O, we
provide arguments that the HDO/H$_2$O ratio should be about 0.01 or larger,
which would be hundreds of times larger than the values measured in Solar
System objects. This suggests the need of strong caution in comparing and
linking the HDO/H$_2$O in Solar System and star forming environments.


title:
The discovery of PSR J1833-1034 : the pulsar associated with the
  supernova remnant G21.5-0.9

abstract:
  We report the discovery of a young pulsar associated with the supernova
remnant G21.5-0.9, using the Giant Metrewave Radio Telescope (GMRT) located
near Pune, India. Discovered at a frequency of 610 MHz, J1833-1034 has a period
of 61.86 ms and a period derivative of $2.0 \times 10^{-13}$, making it similar
to other known young pulsars. The characteristic age of the pulsar is $\approx
4900$ yr, somewhat higher than estimates for the age of the remnant, but not
incompatible with it. The pulsar has a spin-down luminosity of $3.3 \times
10^{37}$ erg s$^{-1}$, which is the second highest amongst all the known
Galactic pulsars.


title:
Chandra and RXTE spectroscopy of the accreting msec pulsar IGR
  J00291+5934

abstract:
  We report on an observation of the recently discovered accreting millisecond
X-ray pulsar IGR J00291+5934 performed with the RXTE-Proportional Counter Array
(PCA) and Chandra-High Energy Transmission Grating Spectrometer (HETGS). The
RXTE data are from a two week follow-up of the source while the Chandra
observation took place around the end of the follow-up, about 12 days after the
discovery of the source, when the source flux had decreased already by a factor
of ten. The analysis of the Chandra data allowed us to extract the most precise
X-ray position of IGR J00291+5934, RA=00 29 03.08 and Dec=+59 34 19.2 (0.6sec
error), compatible with the optical and radio ones. We find that the spectra of
IGR J00291+5934 can be described by a combination of a thermal component and a
power-law. Along the outburst detected by PCA, the power-law photon index shows
no particular trend while the thermal component (~1 keV, interpreted as a hot
spot on the neutron star surface) becomes weaker until non-detection. In the
simultaneous observation of the weak Chandra/RXTE spectrum, there is no more
indication for the ~1 keV thermal component while we detect a colder thermal
component (~0.4 keV) that we interpret as the emission from the cold disc. A
hint for a 6.4 keV iron line is detected, together with an excess around 6.8
keV and absorption feature around 7.1 keV. The latter two features have never
been detected in the spectra of accretion-driven millisecond pulsars before
and, if confirmed, would suggest the presence of an expanding hot corona with
high outflow velocities.


title: 85Peg A: which age for a low metallicity solar like star?

abstract:
  We explore the possible evolutionary status of the primary component of the
binary 85 Pegasi, listed as a target for asteroseismic observations by the MOST
satellite. In spite of the assessed `subdwarf' status, and of the accurate
distance determination from the Hipparcos data, the uncertainties in the
metallicity and age, coupled with the uncertainty in the theoretical models,
lead to a range of predictions on the oscillation frequency spectrum.
Nevertheless, the determination of the ratio between the small separation in
frequency modes, and the large separation as suggested by Roxburgh (2004),
provides a very good measure of the star age, quite independent of the
metallicity in the assumed uncertainty range. In this range, the constraint on
the dynamical mass and the further constraint provided by the assumption that
the maximum age is 14 Gyr limit the mass of 85PegA to the range from 0.75 to
0.82Msun. This difference of a few hundreths of solar masses leads to well
detectable differences both in the evolutionary stage (age) and in the
asteroseismic properties. We show that the age determination which will be
possible through the asteroseismic measurements for this star is independent
either from the convection model adopted or from the microscopic metal
diffusion. The latter conclusion is strengthened by the fact that, although
metal diffusion is still described in an approximate way, recent observations
suggest that the real stars suffer a smaller metal sedimentation with respect
to the models.


title: X-rays from Alpha Centauri - The darkening of the solar twin

abstract:
  We present first results from five XMM-Newton observations of the binary
system Alpha Centauri, which has been observed in snapshot like exposures of
roughly two hours each during the last two years. In all our observations the
X-ray emission of the system is dominated by Alpha Cen B, a K1 star. The
derived light curves of the individual components reveal variability on short
timescales and a flare was discovered on Alpha Cen B during one observation. A
PSF fitting algorithm is applied to the event distribution to determine the
brightness of each component during the observations. We perform a spectral
analysis with multi-temperature models to calculate the X-ray luminosities.We
investigate long term variability and possible activity cycles of both stars
and find the optically brighter component Alpha Cen A, a G2 star very similar
to our Sun, to have fainted in X-rays by at least an order of magnitude during
the observation program, a behaviour never observed before on Alpha Cen A, but
rather similar to the X-ray behaviour observed with XMM-Newton on HD 81809. We
also compare our data with earlier spatially resolved observations performed
over the last 25 years.


title:
The Opacity of Spiral Galaxy Disks: dust opacity from calibrated counts
  of distant galaxies

abstract:
  The opacity of foreground spiral disks can be probed from the number of
distant galaxies seen through them. To calibrate this number for effects other
than the dust extinction, Gonzalez et al (1998) developed the "Synthetic Field
Method". A synthetic field is an extincted Hubble Deep Field added to the
science field. The relation between the dimming and the number of retrieved
synthetic galaxies calibrates the number found in the science field. Here I
present results from counts in 32 HST/WFPC2 fields. The relation between
opacity and radius, arm and disk, surface brightness and HI are presented. The
opacity is found to be caused by a clumpy distribution of clouds in the disk.
The brighter parts of the disk -the center and arms- are also the more opaque
ones. The dust distribution in spiral disks is found to be more extended than
the stellar disk. A comparison between HI column densities and opacity shows
little relation between the two.


title: The Near Infrared Background: Interplanetary Dust or Primordial Stars?

abstract:
  The intensity of the diffuse ~ 1 - 4 micron sky emission from which solar
system and Galactic foregrounds have been subtracted is in excess of that
expected from energy released by galaxies and stars that formed during the z <
5 redshift interval (Arendt & Dwek 2003, Matsumoto et al. 2005). The spectral
signature of this excess near-infrared background light (NIRBL) component is
almost identical to that of reflected sunlight from the interplanetary dust
cloud, and could therefore be the result of the incomplete subtraction of this
foreground emission component from the diffuse sky maps. Alternatively, this
emission component could be extragalactic. Its spectral signature is consistent
with that of redshifted continuum and recombination line emission from HII
regions formed by the first generation of very massive stars. In this paper we
analyze the implications of this spectral component for the formation rate of
these Population III stars, the redshift interval during which they formed, the
reionization of the universe and evolution of collapsed halo masses. We find
that to reproduce the intensity and spectral shape of the NIRBL requires a peak
star formation rate that is higher by about a factor of 4 to 10 compared to
those derived from hierarchical models. Furthermore, an extragalactic origin
for the NIRBL leads to physically unrealistic absorption-corrected spectra of
distant TeV blazars. All these results suggest that Pop III stars contribute
only a fraction of the NIRBL intensity with zodiacal light, star forming
galaxies, and/or non-nuclear sources giving rise to the remaining fraction.


title:
Dark matter in early-type galaxies: dynamical modelling of IC1459,
  IC3370, NGC3379 and NGC4105

abstract:
  We analyse long-slit spectra of four early-type galaxies which extend from ~1
to ~3 effective radii: IC1459, IC3370, NGC3379 and NGC4105. We have extracted
the full line-of-sight velocity distribution (in the case of NGC3379 we also
used data from the literature) which we model using the two-integral approach.
Using two-integral modelling we find no strong evidence for dark haloes, but
the fits suggest that three-integral modelling is necessary. We also find that
the inferred constant mass-to-light ratio in all four cases is typical for
early-type galaxies. Finally, we also discuss the constraints on the
mass-to-light ratio which can be obtained using X-ray haloes in the case of
IC1459, NGC3379 and NGC4105 and compare the estimated values with the
predictions from the dynamical modelling.


title: A New Radio Detection of the Bursting Source GCRT J1745-3009

abstract:
  GCRT J1745-3009 is a transient bursting radio source located in the direction
of the Galactic center, discovered in 330 MHz VLA observations from 2002
September 30--October 1 by Hyman et al. We have searched for bursting activity
from GCRT J1745-3009 in nearly all of the available 330 MHz VLA observations of
the Galactic center since 1989 as well as in 2003 GMRT observations. We report
a new radio detection of the source in 330 MHz GMRT data taken on 2003
September 28. A single ~0.5 Jy burst was detected, approximately 3x weaker than
the five bursts detected in 2002. Due to the sparse sampling of the 2003
observation, only the decay portion of a single burst was detected. We present
additional evidence indicating that this burst is an isolated one, but we
cannot completely rule out additional undetected bursts that may have occured
with the same ~77 min. periodicity observed in 2002 or with a different
periodicity. Assuming the peak emission was detected, the decay time of the
burst, ~2 min, is consistent with that determined for the 2002 bursts. Based on
the total time for which we have observations, we estimate that the source has
a duty cycle of roughly 10%.


title: X-ray obscuration and obscured AGN in the local universe

abstract:
  In this paper we discuss the X-ray properties of 49 local (z<0.035) Seyfert 2
galaxies with HST/WFC2 high-resolution optical coverage. It includes the
results of 26 still unpublished Chandra and XMM-Newton observations, which
yield 25 (22) new X-ray detections in the 0.5-2 keV (2-10 keV) energy band. Our
sample covers a range in the 2-10 keV observed flux from 3x10^{-11} to
6x10^{-15} erg cm$^{-2}$ s$^{-1}$. The percentage of the objects which are
likely obscured by Compton-thick matter (column density, N_H>1.6x10^{24}
atoms/cm/cm) is ~50%, and reaches ~80% for log(F_{2-10})<12.3. Hence, K-alpha
fluorescent iron lines with large Equivalent Width (EW > 0.6 keV) are common in
our sample (6 new detections at a confidence level >2 sigma). They are
explained as due to reflection off the illuminated side of optically thick
material. We confirm a correlation between the presence of a ~100-pc scale
nuclear dust in the WFC2 images and Compton-thin obscuration. We interpret this
correlation as due to the large covering fraction of gas associated with the
dust lanes following an idea originally proposed by Malkan et al. 1998, and
Matt 2000). The X-ray spectra of highly obscured AGN invariably present a
prominent soft excess emission above the extrapolation of the hard X-ray
component. This soft component can account for a very large fraction of the
overall X-ray energy budget. As this component is generally unobscured - and
therefore likely produced in extended gas structures - it may lead to a severe
underestimation of the nuclear obscuration in z~1 absorbed AGN, if standard
X-ray colors are used to classify them. As a by-product of our study, we report
the discovery of a soft X-ray, luminous (~7x10^{40} erg/s) halo embedding the
interacting galaxy pair Mkn266.


title:
Establishing Visible Interferometer System Responses: Resolved and
  Unresolved Calibrators

abstract:
  The propagation of errors through the uniform disk visibility function is
examined. Implications of those errors upon measures of absolute visibility
through optical and near-infrared interferometers are considered within the
context of using calibration stars to establish system visibilities for these
instruments. We suggest a simple ratio test to establish empirically whether or
not the measured visibilities produced by such an instrument are relative
(errors dominated by calibrator angular size prediction error) or absolute
(errors dominated by measurement error).


title: Time-integrated supernova neutrino flux from a nearby cluster

abstract:
  The rate of gravitational collapse (type II) supernovae in our galaxy is
uncertain by a factor of three or more. One way to determine the galactic
supernova rate is through a radiogeochemical experiment (for example, the
molybdenum-technetium experiment) that would integrate the neutrino flux over
several million years. While such a measurement is designed to integrate the
flux over the entire galaxy, nearby star-forming regions could skew the
results. We model the flux from a recently identified such region, the
Scorpius-Centaurus OB association, and compare with the flux from the rest of
the galaxy.


title: CMB component separation by parameter estimation

abstract:
  We propose a solution to the CMB component separation problem based on
standard parameter estimation techniques. We assume a parametric spectral model
for each signal component, and fit the corresponding parameters pixel by pixel
in a two-stage process. First we fit for the full parameter set (e.g.,
component amplitudes and spectral indices) in low-resolution and high
signal-to-noise ratio maps using MCMC, obtaining both best-fit values for each
parameter, and the associated uncertainty. The goodness-of-fit is evaluated by
a chi^2 statistic. Then we fix all non-linear parameters at their
low-resolution best-fit values, and solve analytically for high-resolution
component amplitude maps. This likelihood approach has many advantages: The
fitted model may be chosen freely, and the method is therefore completely
general; all assumptions are transparent; no restrictions on spatial variations
of foreground properties are imposed; the results may be rigorously monitored
by goodness-of-fit tests; and, most importantly, we obtain reliable error
estimates on all estimated quantities. We apply the method to simulated Planck
and six-year WMAP data based on realistic models, and show that separation at
the muK level is indeed possible in these cases. We also outline how the
foreground uncertainties may be rigorously propagated through to the CMB power
spectrum and cosmological parameters using a Gibbs sampling technique.


title: CMB Optical Depth Measurements: Past, Present, Future

abstract:
  The polarization of the cosmic microwave background (CMB) is encoded with
exactly the same cosmic information as the CMB's temperature anistropy.
However, polarization has the additional promise of accurately probing the
reionization history of the universe and potentially constraining, or
detecting, the primordial background of gravitational waves produced by
inflation. We demonstrate that these two CMB polarization goals are mutually
compatible. A polarimeter optimized to detect the inflationary gravitational
wave background signature in the polarization of the CMB is well situated to
detect the signatures of realistic first-light scenarios. We also discuss
current results and prospects for future CMB polarization experiments.


title:
Echelle Spectroscopy of a GRB Afterglow at z=3.969: A New Probe of the
  Interstellar and Intergalactic Media in the Young Universe

abstract:
  We present an echelle spectrum of the Swift GRB 050730, obtained four hours
after the burst using the MIKE spectrograph on the Magellan Clay Telescope when
the afterglow was at R=17.7. The spectrum reveals a forest of absorption
features superimposed on a simple power-law shaped continuum, best described as
f_nu(lambda)\propto lambda^{alpha} with alpha =1.88\pm 0.01 over
lambda=7000-9000 A. We identify the GRB host at z_GRB=3.96855 based on the
hydrogen Lyman absorption series, narrow absorption lines due to heavy ions
such as OI, CII, SiII, SII, NiII, FeII, CIV, SiIV, and NV, and fine structure
transitions such as OI*, OI**, SiII*, CII*, and FeII*. Together these
transitions allow us to study the the properties of the interstellar medium
(ISM) in the GRB host. The principal results are as follows. (1) We estimate a
neutral hydrogen column density of log N(HI)=22.15\pm 0.05 in the host. (2) The
associated metal lines exhibit multiple components over a velocity range of ~80
km/s, with >90% of the neutral gas confined in 20 km/s. (3) Comparisons between
different ionic transitions show that the host has little/no dust depletion and
has 1/100 solar metallicity. (4) The absorbing gas has much higher density than
that of intervening damped Lya absorption (DLA) systems. In addition, we report
the identification of an intervening DLA system at z_DLA=3.56439 with log
N(HI)=20.3\pm 0.1 and < 5% solar metallicity, a Lyman limit system at
z_LLS=3.02209 with log N(HI)=19.9\pm 0.1, a strong MgII absorber at
z_MgII=2.25313, and a pair of MgII absorbers at z_MgII=1.7731, 57 km/s apart.
We demonstrate that rapid echelle spectroscopy of GRB afterglows helps to
reveal a wealth of information in the ISM and the intergalactic medium along
the sightline (abridged).


title: Star Forming Galaxies at z~6 and Reionization

abstract:
  We determine the abundance of i'-band drop-outs in the HST/ACS GOODS surveys
and the Hubble Ultra Deep Field (UDF). The majority of these sources are likely
to be z~6 galaxies whose flux decrement arises from Lyman-alpha absorption. We
have shown with Keck/DEIMOS spectroscopy that this technique does indeed select
high redshift galaxies, and we discovered Lyman-alpha emission for about a
third of the galaxies with z'_AB<25.6 The increased depth of UDF enables us to
reach a ~10sigma limiting magnitude of z'_AB=28.5 (equivalent to 1.5M_sun/yr at
z=6.1, or 0.1L*_UV for the z~3 U-drop population). The star formation rate at
z~6 was approximately x6 LESS than at z~3. This declining comoving star
formation rate poses an interesting challenge for models which suggest that
L_UV>0.1L* star forming galaxies at z~6 reionized the universe. The short-fall
in ionizing photons might be alleviated by galaxies fainter than our limit, or
a radically different IMF. Alternatively, the bulk of reionization might have
occurred at z>>6. We have recently discovered evidence of an early epoch of
star formation in some of the i'-drops at z~6. Spitzer images with IRAC at
3.6-4.5microns show evidence of the age-sensitive Balmer/4000Ang break,
dominated by stars older than 100Myr (and most probably 400Myr old). This
pushes the formation epoch for these galaxies to z_form=7.5-13.5. There are at
least some galaxies already assembled with stellar masses ~3x10^10M_sun
(equivalent to 0.2M* today) within the first billion years. The early formation
of such systems may have played a key role in reionizing the Universe at z~10.


title: Constrained Cosmological Simulations of Dark Matter Halos

abstract:
  The formation and structure of dark matter (DM) halos is studied by means of
constrained realizations of Gaussian fields using N-body simulations. A series
of experiments of the formation of a 10^{12} Msun halo is designed to study the
dependence of the density profile on its merging history. We confirm that the
halo growth consists of violent and quiescent phases, with the density well
approximated by the Navarro-Frenk-White (NFW) profile during the latter phases.
We find that (1) the NFW scale radius R_s stays constant during the quiescent
phase and grows abruptly during the violent one. In contrast, the virial radius
grows linearly during the quiescent and abruptly during the violent phases. (2)
The central density stays unchanged during the quiescent phase while dropping
abruptly during the violent phase. (3) The value of \rs reflects the violent
merging history of the halo, and depends on the number of violent events and
their fractional magnitudes, independent of the time and order of these events.
It does not reflect the formation time of the halo. (4) The fractional change
in R_s is a nonlinear function of the fractional absorbed kinetic energy within
R_s in a violent event.


title:
The MAGIC Project: Contributions to ICRC 2005, Pune, India, Part 2:
  Future Plans and Developments

abstract:
  Contributions by the MAGIC collaboration to ICRC 2005, Pune, India, Part 2:
Future Plans and Developments (9 contributions)


title:
The MAGIC Project: Contributions to ICRC 2005, Pune, India, Part 3:
  MAGIC Detector and Analysis Details

abstract:
  Contributions by the MAGIC collaboration to ICRC 2005, Pune, India, Part 2:
MAGIC Detector and Analysis Details (12 contributions)


title: Gravitational radiation timescales for extreme mass ratio inspirals

abstract:
  The capture and inspiral of compact stellar masses into massive black holes
is an important source of low-frequency gravitational waves (with frequencies
of ~1-100mHz), such as those that might be detected by the planned Laser
Interferometer Space Antenna (LISA). Simulations of stellar clusters designed
to study this problem typically rely on simple treatments of the black hole
encounter which neglect some important features of orbits around black holes,
such as the minimum radii of stable, non-plunging orbits. Incorporating an
accurate representation of the orbital dynamics near a black hole has been
avoided due to the large computational overhead. This paper provides new, more
accurate, expressions for the energy and angular momentum lost by a compact
object during a parabolic encounter with a non-spinning black hole, and the
subsequent inspiral lifetime. These results improve on the Keplerian
expressions which are now commonly used and will allow efficient computational
simulations to be performed that account for the relativistic nature of the
spacetime around the central black hole in the system.


title: Radio observations and spectral index study of SNR G126.2+1.6

abstract:
  We present new images of the low radio surface brightness Supernova Remnant
(SNR) G126.2+1.6, based on the 408 MHz and 1420 MHz continuum emission and the
HI-line emission data of the Canadian Galactic Plane Survey (CGPS). {\bf We
find the SNR's flux densities at 408 MHz (9.7$\pm$3.9 Jy) and 1420 MHz
(6.7$\pm$2.1 Jy) which have been} corrected for flux densities from compact
sources within the SNR. The integrated flux density based spectral index
(S$_{\nu}$$\propto$$\nu$$^{-\alpha}$) is 0.30$\pm$0.41. The respective T-T plot
spectral index is 0.30 $\pm$0.08. We also find spatial variations of spectral
index within the SNR{\bf:0.2-0.6.} HI observations show structures probably
associated with the SNR, i.e, features associated with the SNR's southeastern
filaments in the radial velocity range of -33 to -42 km$/$s, and with its
northwestern filaments in -47 to -52 km$/$s. This association suggests a
distance of 5.6 kpc for SNR G126.2+1.6. The estimated Sedov age for G126.2+1.6
is less than 2.1$\times10^{5}$ yr.


title:
Estimating the kinetic luminosity function of jets from Galactic X-ray
  binaries

abstract:
  By combining the recently derived X-ray luminosity function for Galactic
X-ray binaries (XRBs) by Grimm et al. (2002) and the radio-X-ray-mass relation
of accreting black holes found by Merloni et al. (2003), we derive predictions
for the radio luminosity function and radio flux distribution (logN/logS) for
XRBs. Based on the interpretation that the radio-X-ray-mass relation is an
expression of an underlying relation between jet power and nuclear radio
luminosity, we derive the kinetic luminosity function for Galactic black hole
jets, up to a normalization constant in jet power. We present estimates for
this constant on the basis of known ratios of jet power to core flux for AGN
jets and available limits for individual XRBs. We find that, if XRB jets do
indeed fall on the same radio flux--kinetic power relation as AGN jets, the
estimated mean kinetic luminosity of typical low/hard state jets is of the
order of <W_{XRB}> ~ 2x10^37 ergs/s, with a total integrated power output of W
\~ 5.5x10^38 ergs/s. We find that the power carried in transient jets should be
of comparable magnitude to that carried in low/hard state jets. Including
neutron star systems increases this estimate to W ~ 9x10^38 ergs/s. We estimate
the total kinetic energy output from low/hard state jets over the history of
the Galaxy to be E_{XRB} ~ 7x10^56 ergs.


title:
The synchrotron foreground and CMB temperature-polarization cross
  correlation power spectrum from the first year WMAP data

abstract:
  We analyse the temperature-polarization cross-correlation in the Galactic
synchrotron template that we have recently developed, and between the template
and CMB temperature maps derived from WMAP data. Since the polarized
synchrotron template itself uses WMAP data, we can estimate residual
synchrotron contamination in the CMB $C_\ell^{TE}$ angular spectrum. While
$C_2^{TE}$ appears to be contamined by synchrotron, no evidence for
contamination is found in the multipole range which is most relevant for the
fit of the cosmological optical depth.


title: The Dark Side of the Universe

abstract:
  I will begin by reviewing the evidence for Dark Matter in the Universe, as
well as the candidates for dark matter. At most 20% of the dark matter in
galaxies can be in the form of MACHOs (Massive Compact Halo Objects); the
remainder appears to be some unknown exotic component. The most sensible
candidates from the point of view of particle physics are axions and WIMPs
(Weakly Interacting Massive Particles), where WIMPs may be supersymmetric
particles. Three recent claims of possible detection of WIMP dark matter are
tantalizing and will be discussed: the DAMA annual modulation, the HEAT
positron excess, and gamma-rays from the Galactic Center. In addition, I will
discuss the dependence of signals in detectors on the mass distribution in the
Galactic Halo. In particular, the Sagittarius stream can be a smoking gun for
WIMP detection.


title:
COMPTEL Observations of the Gamma-ray Blazars 3C~454.3 and CTA 102
  During the CGRO Mission

abstract:
  We have investigated the MeV behaviour of the \gray blazars 3C~454.3 and CTA
102 by analyzing all COMPTEL observations of this sky region during the
complete CGRO mission. Both sources are detected by COMPTEL at the upper
COMPTEL energies; although their flux estimates may be uncertain by possible
minor contribution of nearby unidentified EGRET \gray sources. While CTA 102
was only detected at energies above 10 MeV during the early mission, 3C~454.3
is most significantly detected in the COMPTEL 3-10 MeV band in the sum of all
data. Time-resolved analyses indicate a weak (near COMPTEL threshold) but
likely steady 3-10 MeV emission over years, being independent of the observed
time variability at energies above 100 MeV as observed by EGRET. This
energy-dependent variability behaviour suggests different emission mechanisms
at work at the two bands. Putting the COMPTEL fluxes in multifrequency
perspective (radio to \grays), reveals for both sources the typical two-hump
blazar spectra, with a low-energy maximum around the IR and a high-energy
maximum at MeV energies. The latter one dominates the energy output across the
whole electro-magnetic spectrum. The results of our analyses are discussed in
the framework of current blazar modeling.


title: AGN in deep radio/X-ray surveys: hunting the earliest massive galaxies

abstract:
  Despite the plethora of deep (sub-mJy) radio surveys there remains
considerable doubt as to the exact nature of the galaxies contributing to the
source counts. Current evidence suggests that starformation in moderately
luminous 'normal' galaxies is responsible for the bulk of the emission below
1mJy. However given the sensitivities of these surveys we would expect a
fraction of these sources to be distant radio galaxies. Using deep VLA and GMRT
data we have found ~20 high-z candidate radio galaxies in two fields using the
classical ultra-steep radio spectrum technique (De Breuck et al., 2000) and
selecting galaxies with faint (i'>25) optical counterparts. Several of these
sources have X-ray detections in our deep XMM/Chandra observations and have
fluxes high enough to put them in the quasar regime if they lie above redshift
3. Recently performed Spitzer GTO observations and upcoming near-infrared
observations will help reveal the nature of these sources.


title:
A search for planetary-mass objects and brown dwarfs in the Upper
  Scorpius association

abstract:
  We report the results of a deep photometric search for planets and brown
dwarfs in the nearby young OB Upper Scorpius association. We obtained optical
(I) and near-infrared (JKs) images around nine very low-mass stars and brown
dwarf member candidates of the association, covering a total area of 113
arcmin^2. Using a point spread function subtraction technique, we have searched
for planetary-mass companions (0.002 Msol < M < 0.013 Msol) at separations as
close as 3 arcsec from the targets. We have not found any brown dwarfs more
massive than 0.030 Msol at projected distances larger than 70AU, or planets
more massive than 0.007 Msol at projected distances larger than 600AU. We set
an upper limit of 20% (confidence level 68.3%) to the fraction of very low-mass
stars and massive brown dwarfs with planetary mass companions (M > 0.007 Msol)
at physical distances larger than 600AU. From the I, I-J colour-magnitude
diagrams and follow-up Ks-band photometry, we identify four very red objects
(I-J > 2.5) in the area of the survey. According to their positions in the
diagram, below the expected theoretical sequence of the cluster, three are
probable late M-dwarfs in the field. The faintest and reddest object (J-Ks =
2.39 +/- 0.06) may be either a field intermediate L-dwarf with anomalously red
J-Ks colour at a distance of approx. 135pc, an extremely red distant galaxy, or
a reddened planetary-mass object in the Upper Scorpius association.


title: Stellar evolution and the 'O-rich AGB sequence'

abstract:
  The `O-rich AGB sequence' is a well defined area occupied by oxygen-rich AGB
stars (OH/IR) in the IRAS two-colour diagram [12]-[25] vs [25]-[60]. This
sequence is interpreted in terms of evolutionary stage and/or progenitor mass
with the aim to link observed classes of AGB stars and Planetary Nebulae (PNe).


title: Timing the bright X-ray population of the core of M31 with XMM-Newton

abstract:
  All 63 discrete X-ray sources brighter than L_{\rm X} = 5x10^{36} erg/s in
any of four XMM-Newton observations of the core of M31 were surveyed for time
variability over time-scales of seconds to thousands of seconds, and for
intensity variations between observations. This population is likely to be
dominated by low mass X-ray binaries (LMXBs).
  Analysis of the shapes of power density spectra (PDS) of these sources allows
us to determine whether they are accreting at a high or low rate; in the
observed frequency range a broken power law (Type A) PDS indicates a low
accretion rate while a simple power law (Type B) indicates a high accretion
rate. We obtained the 0.3--10 keV luminosities of the sources by modelling
their spectral energy distributions. The luminosity function for Type A PDS
appears to consist of two populations, which we tentatively classify as neutron
star and black hole LMXBs.
  We find that 46 sources are likely X-ray binaries, 13 with possible black
hole primaries. Remarkably, 5 out of the 13 black hole candidates appear
persistently bright; there are no persistently bright black hole LMXBs known in
our Galaxy. The lightcurves of 55 X-ray sources had a probability of
variability >99% in at least one observation. Also, 57 of the sources show a
luminosity variation > ~5$\sigma$ between observations; 7 of these are classed
as transients, since they are absent in at least one observation, and vary in
luminosity by a factor of > ~10. Scaling this sample with the known Galactic
LMXBs, we find that the M31 sample has ~50% of the dippers, Z-sources and
transients.


title: AGB and post-AGB stars

abstract:
  Intermediate mass stars (1-8 solar masses) evolve along the Asymptotic Giant
Branch after completion of hydrogen and helium core burning. At the tip they
lose for several ten to hundred thousand years copious amounts of mass and
exhibit various forms of variability, as for example large-amplitude variations
with periods of one to five years. In the oxygen-rich circumstellar envelopes
powerful OH, H2O and SiO masers may operate. Part of the AGB population is
converted to carbon stars. During the latest phases of AGB evolution the mass
loss rates approach several 10e-5 solar masses/year, so that the stars become
invisible in the optical and in part in the near infrared. On departure from
the AGB a fundamental transition in the mass loss process is taking place
changing from a spherically symmetric outflow on the AGB to axi-symmetric or
point-symmetric geometries. While the mass loss rates decrease to ~10e-8 solar
masses/year, the velocities are strongly increasing. Stars are now in their
"post-AGB" phase. Mounting evidence is gathered that during the very latest
phase of AGB evolution and during the post-AGB phase, evolution proceeds on
very short timescales, which in extreme cases is comparable to the working life
of an astronomer.


title: Investigating the 2nd knee: The KASCADE-Grande experiment

abstract:
  Recent results from the multi-detector set-up KASCADE on measurements of
cosmic rays in the energy range of the so called "first" knee (at approx. 3
PeV) indicate a distinct knee in the energy spectra of light primary cosmic
rays and an increasing dominance of heavy ones towards higher energies. This
leads to the expectation of knee-like features of the heavy primaries at around
100 PeV. To investigate this energy region KASCADE has recently been extended
by a factor 10 in area to the new experiment KASCADE-Grande. Main results of
KASCADE as well as set-up, capabilities, and status of KASCADE-Grande are
presented.


title:
Intracluster Entropy from Joint X-ray and Sunyaev-Zel'dovich
  Observations

abstract:
  The temperature and density of the hot diffuse medium pervading galaxy groups
and clusters combine into one significant quantity, the entropy. Here we
express the entropy levels and profiles in model-independent forms by joining
two observables, the X-ray luminosity and the change in the CMB intensity due
to the Sunyaev-Zel'dovich (SZ) effect. Thus we present both global scaling
relations for the entropy levels from clusters and groups, and a simple
expression yielding the entropy profiles in individual clusters from resolved
X-ray surface brightness and SZ spatial distributions. We propose that our
approach provides two useful tools for comparing large data samples with
models, in order to probe the processes that govern the thermal state of the
hot intracluster medium. The feasibility of using such a diagnostic for the
entropy is quantitatively assessed, based on current X-ray and upcoming SZ
measurements.


title:
Near infrared imaging of the broad absorption line quasar BAL QSO
  0134+3253

abstract:
  In this paper we present near infrared (NIR) imaging data of the host galaxy
of the broad absorption line quasar (BALQ) at z=2.169, serendipitously found
close to 3C48. The data were obtained with the ESO-VLT camera ISAAC during
period 67. We find extended, rest-frame optical emission around the BALQ after
subtracting a scaled stellar point spread function from the quasar nucleus in
J, H, and Ks. The extended rest-frame optical emission can be interpreted as an
approximately 2 Gyr old stellar population composing the host galaxy of the
BALQ or a stellar population of similar age associated with an intermediate
(z=1.667) absorption system spectroscopically identified by Canalizo & Stockton
(1998) simultaneously. The rest-frame-UV emission on the other hand is
dominated by a young, 500 Myr old stellar population. The UV/optical colors
resemble a mixture of the two populations, of which the young one accounts for
about 80%. Assuming that the residual emission is located at the BALQ redshift,
we find that the host galaxy has a resolved flux of about 10% of the BALQ flux.
The physical scale is quite compact, typical for radio quiet QSOs or Lyman
break galaxies at these redshifts, indicating that the systems are still in the
process of forming.


title: The X-ray Properties of M101 ULX-1 = CXOKM101 J140332.74+542102

abstract:
  We report our analysis of X-ray data on M101 ULX-1, concentrating on high
state Chandra and XMM-Newton observations. We find that the high state of M101
ULX-1 may have a preferred recurrence timescale. If so, the underlying clock
may have periods around 160 or 190 days, or possibly around 45 days. Its
short-term variations resemble those of X-ray binaries at high accretion rate.
If this analogy is correct, we infer that the accretor is a 20-40 Msun object.
This is consistent with our spectral analysis of the high state spectra of M101
ULX-1, from which we find no evidence for an extreme (> 10^40 ergs/s)
luminosity. We present our interpretation in the framework of a high mass X-ray
binary system consisting of a B supergiant mass donor and a large stellar-mass
black hole.


title: Equations of Motion in a Quantum-mechanical Theory of Gravity

abstract:
  An earlier paper [1] presented a gravity theory based on the optics of de
Broglie waves rather than curved space-time. While the universe's geometry is
flat, it agrees with the standard tests of general relativity. A second paper
[2] showed that, unlike general relativity, it agrees with Doppler tracking
signals from the Pioneer 10 and 11 space probes. There a gravitational
acceleration equation plays an important role, accounting for the relative
motions of Earth and the probes. Here it's shown that equation also describes
Mercury's orbit.


title:
Global characteristics of the first IBIS/ISGRI catalogue sources:
  unveiling a murky episode of binary star evolution

abstract:
  INTEGRAL is the first gamma-ray astronomy mission with a sufficient
sensitivity and angular resolution combination appropriate to the detection and
identification of considerable numbers of gamma-ray emitting sources. The large
field of view enables INTEGRAL to survey the galactic plane on a regular
(~weekly) basis as part of the core programme. The first source catalogue,
based on the 1st year of core programme data has been completed and published
(Bird et al., 2004). It contained 123 gamma-ray sources (24 HMXB, 54 LMXB, 28
``unknown'', plus 17 others) - sufficient numbers for a reasonable statistical
analysis of their global properties. The detection of previously unknown
gamma-ray emitting sources generally exhibiting high intrinsic absorption, is
intriguing. The substantial fraction of unclassified gamma-ray sources suggests
they must constitute a significant family of objects. In this paper we review
the global characteristics of the known galactic sources as well as the
unclassified objects. We present Log(N)-Log(S) distributions, angular
distributions, and for systems with reliable distance estimates the spatial
distributions within the Galaxy and luminosity functions. For the unknown
sources, this statistical analysis has shown that they are most likely to be
HMXBs containing a highly magnetised neutron star. The lack of X-ray
counterparts for these sources indicates a high degree of intrinsic
obscuration.


title:
Relativistic scaling of astronomical quantities and the system of
  astronomical units

abstract:
  For relativistic modelling of high-accuracy astronomical data several time
scales are used: barycentric and geocentric coordinate times, TCB and TCG, as
well as two additional time scales, TDB and TT, that are defined as linear
functions of TCB and TCG, respectively.
  The paper is devoted to a concise but still detailed explanation of the
reasons and the implications of the relativistic scalings of astronomical
quantities induced by the time scales TDB and TT.
  We consequently distinguish between quantities and their numerical values
expressed in some units.
  It is argued that the scaled time scales, the scaled spatial coordinates and
the scaled masses should be considered as distinct quantities which themselves
can be expressed in any units, and not as numerical values of the same
quantities expressed in some different, non-SI units (``TDB units'' and ``TT
units'').
  Along the same lines of argumentation the system of astronomical units is
discussed in the relativistic framework. The whole freedom in the definitions
of the systems of astronomical units for TCB and TDB is demonstrated. A number
of possible ways to freeze the freedom are shown and discussed. It is argued
that in the future one should think about converting AU into a defined quantity
by fixing its value in SI meters.


title: Detectability of tensor modes in the presence of foregrounds

abstract:
  In inflationary models, gravitational waves are produced and generate B-type
polarization in the CMB. Since B polarization is only generated by gravity
waves it does not suffer from the cosmic variance. A perfect decomposition of
the CMB into B-modes and E-modes would require data from the entire sky, which
in practice is not possible because of the foreground contaminants. This leads
to mixing of E polarization into B, which introduces cosmic variance conta-
mination of B polarization and reduces sensitivity to gravity wave amplitude
even in absence of detector noise. We present numerical results for the
uncertainty in the tensor-to-scalar ratio using the Fisher matrix formalism for
various resolutions, using foreground models based on dust maps and assuming 90
GHz operating frequency. We find that the usual scaling delta(T/S) ~
f_sky^(-1/2) is significantly degraded and becomes delta(T/S) ~ f_sky^(-2) for
f_sky>0.7. This dependence is affected only weakly by the choice of sky cuts.
To achieve a T/S=10^(-3) detection at 3 sigma one needs to observe 15% of the
sky as opposed to naive expectation of 0.3%. To prevent contamination over this
large sky area at required level one must be able to remove polarized dust
emission at or better than 0.1% of unpolarized intensity, assuming the cleanest
part of the sky has been chosen. To achieve T/S=10^(-4) detection at 3 sigma
one needs to observe 70% of the sky, which is only possible if dust emission is
removed everywhere over this region at 0.01% level. Reaching T/S=10^(-2) should
be easier: 1% of the sky is needed over which polarized emission needs to be
removed at 1% of total intensity if the cleanest region is chosen. These
results suggest that foreground contamination may make it difficult to achieve
levels below T/S=10^(-3). (abridged)


title: Are we observing Lorentz violation in gamma ray bursts?

abstract:
  From recent observations of gamma-ray bursts (GRBs), it appears that spectral
time lags between higher-energy gamma rays photons and lower-energy photons
vary with energy difference and time (distance) traveled. These lags appear to
be smaller for the most luminous (close) bursts but larger for the fainter
(farther away) bursts. From this observation, it has been suggested that it
might be possible to determine the distance (L) these bursts have traveled from
these time lags alone, without performing any red-shift measurements. These
observed spreads (dispersion) of high-energy electromagnetic pulses of
different energies with time contradict the special theory of relativity (STR).
However, extended theories (ET) of the STR have been developed that contain a
dispersive term, predicting the above observations. An example of such an ET is
presented, allowing us to derive a relationship between time lags of gamma rays
of different energies and distance L traveled from their origin. In addition,
this theory predicts the origin of X-ray flashes.


title: Controlling the collimation and rotation of hydromagnetic disk winds

abstract:
  (Abriged) We present a comprehensive set of axisymmetric, time-dependent
simulations of jets from Keplerian disks whose mass loading as a function of
disk radius is systematically changed. For a reasonable model for the density
structure and injection speed of the underlying accretion disk, mass loading is
determined by the radial structure of the disk's magnetic field structure. We
vary this structure by using four different magnetic field configurations,
ranging from the "potential" configuration (Ouyed&Pudritz 1997), to the
increasingly more steeply falling Blandford&Payne (1982) and Pelletier&Pudritz
(1992) models, and ending with a quite steeply raked configuration that bears
similarities to the Shu X-wind model. We find that the radial distribution of
the mass load has a profound effect on both the rotational profile of the
underlying jet as well as the degree of collimation of its outflow velocity and
magnetic field lines. We show analytically, and confirm by our simulations,
that the collimation of a jet depends on its radial current distribution, which
in turn is prescribed by the mass load. Models with steeply descending mass
loads have strong toroidal fields, and these collimate to cylinders (this
includes the Ouyed-Pudritz and Blandford-Payne outflows). On the other hand,
the more gradually descending mass load profiles (the PP92 and monopolar
distributions) have weaker toroidal fields, and these result in wide-angle
outflows with parabolic collimation. We also present detailed structural
information about jets such as their radial profiles of jet density, toroidal
magnetic field, and poloidal jet speed, as well as an analysis of the bulk
energetics of our different simulations.


title: Reduced Shear Power Spectrum

abstract:
  Measurements of ellipticities of background galaxies are sensitive to the
reduced shear, the cosmic shear divided by $(1-\kappa)$ where $\kappa$ is the
projected density field. We compute the difference between shear and reduced
shear both analytically and with simulations. The difference becomes more
important on smaller scales, and will impact cosmological parameter estimation
from upcoming experiments. A simple recipe is presented to carry out the
required correction.


title: Spatial and Dynamical Properties of Voids in a LCDM Universe

abstract:
  We study statistical properties of voids in the distribution of mass,
dark-matter haloes and galaxies (B_J<-16) in a LCDM numerical simulation
populated with galaxies using a semi-analytic galaxy formation model(GALFORM,
Cole et al. 2000). We find that the properties of voids selected from GALFORM
galaxies are compatible with those of voids identified from a population of
haloes with mass M>10^11.5 M_sun/h, similar to the median halo mass,
M_med=10^11.3 M_sun/h. We also find that the number density of galaxy- and
halo-defined voids can be up to two orders of magnitude higher than
mass-defined voids for large void radii. As expected, there are outflow
velocities which show their maximum at larger void-centric distances for larger
voids (well described by a linear relation). The void-centric distance where
this maximum occurs, follows a suitable power law fit of the form,
log(d_vmax)=(r_void/A)^B. At sufficiently large distances, we find mild infall
motions onto the sub-dense regions. We find that a similar analysis in redshift
space would make both outflows and infalls to appear with a lower amplitude. We
also find that the velocity dispersion of galaxies and haloes is larger in the
direction parallel to the void walls by ~10-20%. We analyse the void-tracer
cross-correlation functions in real- and redshift-space as a function of
separation, and also as a function of separations parallel and perpendicular to
the line of sight. The distortion pattern observed in xi(sigma,pi) is that of
an elongation along the line of sight which extends out to large separations.
Positive xi contours evidence finger-of-god motions at the void walls.
Elongations along the line of sight are roughly comparable between galaxy-,
halo- and mass-defined voids. (Abridged)


title: Discovery of very high energy gamma-rays associated with an X-ray binary

abstract:
  X-ray binaries are composed of a normal star in orbit around a neutron star
or stellar-mass black hole. Radio and X-ray observations have led to the
presumption that some X-ray binaries called microquasars behave as scaled down
active galactic nuclei. Microquasars have resolved radio emission that is
thought to arise from a relativistic outflow akin to active galactic nuclei
jets, in which particles can be accelerated to large energies. Very high energy
gamma-rays produced by the interactions of these particles have been observed
from several active galactic nuclei. Using the High Energy Stereoscopic System,
we find evidence for gamma-ray emission >100 GeV from a candidate microquasar,
LS 5039, showing that particles are also accelerated to very high energies in
these systems.


title: The Evolution in the Faint-End Slope of the Quasar Luminosity Function

abstract:
  (Abridged) Based on numerical simulations of galaxy mergers that incorporate
black hole (BH) growth, we predict the faint end slope of the quasar luminosity
function (QLF) and its evolution with redshift. Our simulations have yielded a
new model for quasar lifetimes where the lifetime depends on both the
instantaneous and peak quasar luminosities. This motivates a new interpretation
of the QLF in which the bright end consists of quasars radiating at nearly
their peak luminosities, but the faint end is mostly made up of quasars in less
luminous phases of evolution. The faint-end QLF slope is then determined by the
faint-end slope of the quasar lifetime for quasars with peak luminosities near
the observed break. We determine this slope from the quasar lifetime as a
function of peak luminosity, based on a large set of simulations spanning a
wide variety of host galaxy, merger, BH, and ISM gas properties. Brighter peak
luminosity (higher BH mass) systems undergo more violent evolution, and expel
and heat gas more rapidly in the final stages of quasar evolution, resulting in
a flatter faint-end slope (as these objects fall below the observed break in
the QLF more rapidly). Therefore, as the QLF break luminosity moves to higher
luminosities with increasing redshift, implying a larger typical quasar peak
luminosity, the faint-end QLF slope flattens. From the quasar lifetime as a
function of peak luminosity and this interpretation of the QLF, we predict the
faint-end QLF slope and its evolution with redshift in good agreement with
observations. Although BHs grow anti-hierarchically (with lower-mass BHs formed
primarily at lower redshifts), the observed change in slope and differential or
luminosity dependent density evolution in the QLF is completely determined by
the luminosity-dependent quasar lifetime and physics of quasar feedback.


title:
The Arecibo Legacy Fast ALFA Survey: II. Results of Precursor
  Observations

abstract:
  In preparation for the full Arecibo Legacy Fast ALFA extragalactic HI survey,
precursor observations were carried out in Aug--Sep 2004 with the 7-beam
Arecibo L-band feed array (ALFA) receiver system and the WAPP spectral
processors. While these observations were geared mainly at testing and
debugging survey strategy, hardware and software, approximately 36 hours of
telescope time yielded science--quality data. From those observations, an
initial list of 730 tentative detections of varying degree of reliability was
extracted. Ninety--eight high signal-to-noise candidates were deemed to be bona
fide HI line detections. To test our ability to discriminate cosmic signals
from RFI and noise, 165 candidates ranging in reliability likelihood were
re--observed with the single beam L--band wide system at Arecibo in Jan--Feb
2005. Of those, 41% were confirmed as real. We present the results of both the
ALFA and single beam observations for the sample of 166 confirmed HI sources,
as well as our assessment of their optical counterparts. Of the 166 sources, 62
coincide with previously known HI sources, while optical redshifts were
available for an additional 18 galaxies; thus, 52% of the redshifts reported
here were previously unknown. Of the 166 HI detections, 115 are identified with
previously cataloged galaxies, of either known or unknown redshift, leaving 51
objects identified for the first time. Because of the higher sensitivity of the
Arecibo system, fewer than 10% of the 166 HI sources would have been detected
by a HIPASS--like survey of the same region. Three of the objects have HI
masses less than 10^7 solar masses. The full ALFALFA survey which commenced in
February 2005 should detect more than 100 times as many objects of similarly
low HI mass over the next 5 years.


title:
The Arecibo Legacy Fast ALFA Survey: I. Science Goals, Survey Design and
  Strategy

abstract:
  The recently initiated Arecibo Legacy Fast ALFA (ALFALFA) survey aims to map
7000 square degrees of the high galactic latitude sky visible from Arecibo,
providing a HI line spectral database covering the redshift range between -1600
km/s and 18,000 km/s with 5 km/s resolution. Exploiting Arecibo's large
collecting area and small beam size, ALFALFA is specifically designed to probe
the faint end of the HI mass function in the local universe and will provide a
census of HI in the surveyed sky area to faint flux limits, making it
especially useful in synergy with wide area surveys conducted at other
wavelengths. ALFALFA will also provide the basis for studies of the dynamics of
galaxies within the Local and nearby superclusters, will allow measurement of
the HI diameter function, and enable a first wide-area blind search for local
HI tidal features, HI absorbers at z < 0.06 and OH megamasers in the redshift
range 0.16 < z < 0.25. Although completion of the survey will require some five
years, public access to the ALFALFA data and data products will be provided in
a timely manner, thus allowing its application for studies beyond those
targeted by the ALFALFA collaboration. ALFALFA adopts a two-pass, minimum
intrusion, drift scan observing technique which samples the same region of sky
at two separate epochs to aid in the discrimination of cosmic signals from
noise and terrestrial interference. Survey simulations, which take into account
large scale structure in the mass distribution and incorporate experience with
the ALFA system gained from tests conducted during its commissioning phase,
suggest that ALFALFA will detect on the order of 20,000 extragalactic HI line
sources out to z=0.06, including several hundred with HI masses of less than
10^{7.5} msun.


title:
Estimating the Spin of Stellar-Mass Black Holes via Spectral Fitting of
  the X-ray Continuum

abstract:
  We fit X-ray spectral data in the thermal dominant or high soft state of two
dynamically confirmed black holes, GRO J1655-40 and 4U 1543-47, and estimate
the dimensionless spin parameters a* = a/M of the two holes. For GRO J1655-40,
using a spectral hardening factor computed for a non-LTE relativistic accretion
disk, we estimate a* ~ 0.75 and ~ 0.65-0.75, respectively, from ASCA and RXTE
data. For 4U 1543-47, we estimate a* ~ 0.75-0.85 from RXTE data. Thus, neither
black hole has a spin approaching the theoretical maximum a* = 1.


title:
The stellar velocity dispersion in the inner 1.3 disk scale-lengths of
  the irregular galaxy NGC 4449

abstract:
  We present measurements of the stellar velocity dispersion in the inner 1
arcmin radius (1.3 disk scale-lengths) of the irregular galaxy NGC 4449
determined from long-slit absorption-line spectra. The average observed
dispersion is 29 +/-2 km/s, the same as predicted from NGC 4449's luminosity.
No significant rotation in the stars is detected. If we assume a maximum
rotation speed of the stars from the model determined from the gas kinematics
of Hunter et al. (2002), the ratio V_max/sigma_z measured globally is 3. This
ratio is comparable to values measured in spiral galaxies, and implies that the
stellar disk in NGC 4449 is kinematically relatively cold. The intrinsic
minor-to-major axis ratio (b/a)_0 is predicted to be in the range 0.3-0.6,
similar to values derived from the distribution of observed b/a of Im galaxies.
However, V/sigma_z measured locally is 0.5-1.1, and so the circular velocity of
NGC 4449 is comparable or less than the velocity of the stars within the
central 1.3 disk scale-lengths of the galaxy.