title: The UCSD Radio-Selected Quasar Survey for Damped Lyman alpha System

abstract:
  As large optical quasar surveys for damped Lya become a reality and the study
of star forming gas in the early Universe achieves statistical robustness, it
is now vital to identify and quantify the sources of systematic error. Because
the nature of optically-selected quasar surveys makes them vulnerable to dust
obscuration, we have undertaken a radio-selected quasar survey for damped Lya
systems to address this bias. We present the definition and results of this
survey. We then combine our sample with the CORALS dataset to investigate the
HI column density distribution function f(N) of damped Lya systems toward
radio-selected quasars. We find that f(N) is well fit by a power-law f(N) = k_1
N^alpha_1, with log k_1 = 22.90 and alpha_1 = -2.18. This power-law is in
excellent agreement with that of optically-selected samples at low N(HI), an
important yet expected result given that obscuration should have negligible
effect at these gas columns. However, because of the relatively small size of
the radio-selected sample, 26 damped Lya systems in 119 quasars, f(N) is not
well constrained at large N(HI) and the first moment of the HI distribution
function, Omega_g, is, strictly speaking, a lower limit. The power-law is steep
enough, however, that extrapolating it to higher column densities implies only
a modest, logarithmic increase in Omega_g. The radio-selected value of Omega_g
= 1.15 x 10^-3, agrees well with the results of optically-selected surveys.
While our results indicate that dust obscuration is likely not a major issue
for surveys of damped Lya systems, we estimate that a radio-selected sample of
approximately 100 damped Lya systems will be required to obtain the precision
necessary to absolutely confirm an absence of dust bias.


title:
Cosmological parameters from combining the Lyman-alpha forest with CMB,
  galaxy clustering and SN constraints

abstract:
  We combine the Ly-alpha forest power spectrum (LYA) from the Sloan Digital
Sky Survey (SDSS) and high resolution spectra with cosmic microwave background
(CMB) including 3-year WMAP, and supernovae (SN) and galaxy clustering
constraints to derive new constraints on cosmological parameters. The existing
LYA power spectrum analysis is supplemented by constraints on the mean flux
decrement derived using a principle component analysis for quasar continua,
which improves the LYA constraints on the linear power. We find some tension
between the WMAP3 and LYA power spectrum amplitudes, at the ~2 sigma level,
which is partially alleviated by the inclusion of other observations: we find
\sigma_8=0.85\pm 0.02 compared to sigma_8=0.80 \pm 0.03 without LYA. For the
slope we find ns=0.965\pm0.012. We find no evidence for the running of the
spectral index in the combined analysis, dn/dln k=-(1.5\pm 1.2) x 10^{-2}, in
agreement with inflation. The limits on the sum of neutrino masses are
significantly improved: $\sum m_{\nu}<0.17\eV$ at 95% (<0.32eV at 99.9%). This
result, when combined with atmospheric and solar neutrino mixing constraints,
requires that the neutrino masses cannot be degenerate, m_3/m_1>1.3 (95% c.l.).
Assuming a thermalized fourth neutrino we find m_s<0.26\eV at 95% c.l. and such
neutrino cannot be an explanation for the LSND results. In the limits of
massless neutrinos we obtain the effective number of neutrinos N_\nu^{\rm
eff}=5.3^{+0.4}_{-0.6}{}^{+2.1}_{-1.7}{}^{+3.8}_{-2.5} and N_\nu^{\rm eff}=3.04
is allowed only at 2.4-sigma. The constraint on the dark energy equation of
state is w=-1.04\pm 0.06. The constraint on curvature is Omega_k=-0.003\pm
0.006. Cosmic strings limits are G\mu <2.3 x 10^{-7} at 95% c.l. and correlated
isocurvature models are also tightly constrained.


title:
Resolving the Dusty Circumstellar Structure of the Enigmatic Symbiotic
  Star CH Cygni with the MMT Adaptive Optics System

abstract:
  We imaged the symbiotic star CH Cyg and two PSF calibration stars using the
unique 6.5m MMT deformable secondary adaptive optics system. Our
high-resolution (FWHM=0.3"), very high Strehl (98%+-2%) mid-infrared (9.8 and
11.7 um) images of CH Cyg allow us to probe finer length scales than ever
before for this object. CH Cyg is significantly extended compared to our
unresolved PSF calibration stars (Mu UMa and Alpha Her) at 9.8 and 11.7 um. We
estimated the size of the extension by convolving a number of simple Gaussian
models with the Mu UMa PSF and determining which model provided the best fit to
the data. Adopting the Hipparcos distance for this object of 270 pc, we found a
nearly Gaussian extension with a FWHM at 9.8 um of ~40.5+-2.7 AU (0.15+-0.01")
and a FWHM at 11.7 um of 45.9+-2.7 AU (0.17+-0.01"). After subtracting out the
Gaussian component of the emission (convolved with our PSF), we found a faint
\~0.7" asymmetric extension which peaks in flux ~0.5" north of the stars. This
extension is roughly coincident with the northern knotlike feature seen in HST
WFPC2 images obtained in 1999.


title: Periodic Modulations in an X-ray Flare from Sagittarius A*

abstract:
  We present the highly significant detection of a quasi-periodic flux
modulation with a period of 22.2 min seen in the X-ray data of the Sgr A* flare
of 2004 August 31. This flaring event, which lasted a total of about three
hours, was detected simultaneously by EPIC on XMM-Newton and the NICMOS
near-infrared camera on the HST. Given the inherent difficulty in, and the lack
of readily available methods for quantifying the probability of a periodic
signal detected over only several cycles in a data set where red noise can be
important, we developed a general method for quantifying the likelihood that
such a modulation is indeed intrinsic to the source and does not arise from
background fluctuations. We here describe this Monte Carlo based method, and
discuss the results obtained by its application to a other XMM-Newton data
sets. Under the simplest hypothesis that we witnessed a transient event that
evolved, peaked and decayed near the marginally stable orbit of the
supermassive black hole, this result implies that for a mass of 3.5 x 10^{6}
Msun, the central object must have an angular momentum corresponding to a spin
parameter of a=0.22.


title: A Flare of AE Aquarii Observed with XMM-Newton

abstract:
  We present the results of analyzing the XMM-Newton data obtained in 2001
November 7 - 8. A flare is observed simultaneously in X-ray and UV together
with a quiescence. We find that during the flare event X-ray flux varies with
UV with no significant time lag, indicating a close correlation of flux
variation for X-ray and UV flares. An upper limit of the lag is estimated to be
\~1 min. From a timing analysis for X-ray data, we find that both pulsed and
unpulsed flux increase clearly as the flare advances in the entire energy band
0.15 - 10 keV. The net increase of pulsed flux to the quiescence is, however,
small and corresponds to about 3 - 4% of the increase in unpulsed flux,
confirming that a flux variation of flare in AE Aqr is dominated by unpulsed
X-rays. A spectral analysis reveals that the energy spectrum is similar to that
of the quiescence at the beginning of the flare, but the spectrum becomes
harder as the flare advances. Based on these results, we discuss the current
issues that need to be clarified, e.g., the possible flaring site and the mass
accretion problem of the white dwarf. We also discuss the flare properties
obtained in this study.


title:
Telescope Spectrophotometric and Absolute Flux Calibration, and National
  Security Applications, Using a Tunable Laser on a Satellite

abstract:
  We propose a tunable laser-based satellite-mounted spectrophotometric and
absolute flux calibration system, to be utilized by ground- and space-based
telescopes. As spectrophotometric calibration may play a significant role in
the accuracy of photometric redshift measurement, and photometric redshift
accuracy is important for measuring dark energy using SNIa, weak gravitational
lensing, and baryon oscillations, a method for reducing such uncertainties is
needed. We propose to improve spectrophotometric calibration, currently
obtained using standard stars, by placing a tunable laser and a wide-angle
light source on a satellite by early next decade (perhaps included in the
upgrade to the GPS satellite network) to improve absolute flux calibration and
relative spectrophotometric calibration across the visible and near-infrared
spectrum. As well as fundamental astrophysical applications, the system
proposed here potentially has broad utility for defense and national security
applications such as ground target illumination and space communication.


title:
Dissipative transformation of non-nucleated dwarf galaxies into
  nucleated systems

abstract:
  Recent photometric observations by the {\it Hubble Space Telescope (HST)}
have revealed the physical properties of stellar galactic nuclei in nucleated
dwarf galaxies in the Virgo cluster of galaxies. In order to elucidate the
formation processes of nucleated dwarfs, we numerically investigate gas
dynamics, star formation, and chemical evolution within the central 1 kpc of
gas disks embedded within the galactic stellar components of non-nucleated
dwarfs. We find that high density, compact stellar systems can be formed in the
central regions of dwarfs as a result of dissipative, repeated merging of
massive stellar and gaseous clumps developed from nuclear gaseous spiral arms
as a result of local gravitational instability. The central stellar components
are found to have stellar masses which are typically $~$5% of their host dwarfs
and show very flattened shapes, rotational kinematics, and central velocity
dispersions significantly smaller than those of their host dwarfs. We also find
that more massive dwarfs can develop more massive, more metal-rich, and higher
density stellar systems in their central regions, because star formation and
chemical enrichment proceed more efficiently owing to the less dramatic
suppression of star formation by supernovae feedback effects in more massive
dwarfs. Based on these results, we suggest that gas-rich, non-nucleated dwarfs
can be transformed into nucleated ones as a result of dissipative gas dynamics
in their central regions. We discuss the origin of the observed correlations
between physical properties of stellar galactic nuclei and those of their host
galaxies.


title:
Low- and Medium-Dispersion Spectropolarimetry of Nova V475 Sct (Nova
  Scuti 2003): Discovery of an Asymmetric High-Velocity Wind in a Moderately
  Fast Nova

abstract:
  We present low-resolution ($R\sim 90$) and medium-resolution ($R\sim 2500$)
spectropolarimetry of Nova V475 Sct with the HBS instrument, mounted on the
0.91-m telescope at the Okayama Astrophysical Observatory, and with FOCAS,
mounted on the 8.2-m Subaru telescope. We estimated the interstellar
polarization toward the nova from the steady continuum polarization components
and H$\alpha$ line emission components. After subtracting the interstellar
polarization component from the observations, we found that the H$\alpha$
emission seen on 2003 October 7 was clearly polarized. In the polarized flux
spectrum, the H$\alpha$ emission had a distinct red wing extending to $\sim
+4900$ km s$^{-1}$ and a shoulder around $+3500$ km s$^{-1}$, showing a
constant position angle of linear polarization $\theta_{\rm *}\simeq
155\arcdeg\pm 15\arcdeg$. This suggests that the nova had an asymmetric outflow
with a velocity of $v_{\rm wind}\simeq 3500$ km s$^{-1}$ or more, which is six
times higher than the expansion velocity of the ionized shell at the same
epoch. Such a high-velocity component has not previously been reported for a
nova in the `moderately fast' speed class. Our observations suggest the
occurrence of violent mass-loss activity in the nova binary system even during
the common-envelope phase. The position angle of the polarization in the
H$\alpha$ wing is in good agreement with that of the continuum polarization
found on 2003 September 26 ($p_{\rm *}\simeq 0.4$--0.6 %), which disappeared
within the following 2 d. The uniformity of the PA between the continuum
polarization and the wing polarization on October 7 suggests that the axis of
the circumstellar asymmetry remained nearly constant during the period of our
observations.


title: Evidence for a Cosmological Phase Transition From the Dark Energy Scale

abstract:
  A finite vacuum energy density implies the existence of a UV scale for
gravitational modes. This gives a phenomenological scale to the dynamical
equations governing the cosmological expansion that must satisfy constraints
consistent with quantum measurability and spatial flatness. Examination of
these constraints for the observed dark energy density establishes a time
interval from the transition to the present, suggesting major modifications
from the thermal equations of state far from Planck density scales. The
assumption that a phase transition initiates the radiation dominated epoch is
shown under several scenarios to produce fluctuations to the CMB of the order
observed. Quantum measurability constraints (eg. uncertainly relations) define
cosmological scales bounded by luminal expansion rates. It is shown that the
dark energy can consistently be interpreted as being due to the vacuum energy
of collective gravitational modes which manifest as the zero-point motions of
coherent Planck scale mass units prior to the UV scale onset of gravitational
quantum de-coherence for the cosmology.


title: The nature of the DLS fast transients

abstract:
  The discovery and study of highly transient sources, especially those which
rise to high brightness and then fade to obscurity, has been a major part of
modern astrophysics. Well known examples include supernovae and novae. A
byproduct of the Deep Lens Survey was the discovery of three transients which
varied on a timescale of less than an hour. All three had faint and red
counterparts, the brightest of which was identified with an M star. However,
the remaining two showed hints of an extragalactic origin, one had a spatially
extended counterpart and the other appeared in projection on the outskirts of a
bright elliptical galaxy. If these two sources were really of an extragalactic
origin then the two events represent a new class of exotic explosive
transients. We undertook spectroscopic observations with the Keck telescope and
find the two counterparts are also late type Galactic dwarfs. Our main
conclusion is that flares from M dwarfs constitute a dense foreground fog and
dominate over any plausible class of extragalactic fast transients by at least
two orders of magnitude. Overcoming this fog will likely require dedicated
surveys with careful optimization of target field location, filter(s) and
cadence, pre-search imaging to filter out late type dwarfs and a well planned
rapid followup plan.


title:
A photon breeding mechanism for the high-energy emission of relativistic
  jets

abstract:
  We propose a straightforward and efficient mechanism for the high-energy
emission of relativistic astrophysical jets associated with an exchange of
interacting high-energy photons between the jet and the external environment.
Physical processes playing the main role in this mechanism are
electron-positron pair production by photons and the inverse Compton
scattering. This scenario has been studied analytically as well as with
numerical simulations demonstrating that a relativistic jet (with the Lorentz
factor larger than 3--4) moving through the sufficiently dense, soft radiation
field inevitably undergoes transformation into a luminous state. The process
has a supercritical character: the high-energy photons breed exponentially
being fed directly by the bulk kinetic energy of the jet. Eventually particles
feed back on the fluid dynamics and the jet partially decelerates. As a result,
a significant fraction (at least 20 per cent) of the jet kinetic energy is
converted into radiation mainly in the MeV -- GeV energy range. The mechanism
maybe responsible for the bulk of the emission of relativistic jets in active
galactic nuclei, microquasars and gamma-ray bursts.


title: Accretion-powered Millisecond Pulsar Outbursts

abstract:
  The population of accretion-powered millisecond pulsars has grown rapidly
over the last four years, with the discovery of six new examples to bring the
total sample to seven. While the first six discovered are transients active for
a few weeks every two or more years, the most recently-discovered source HETE
J1900.1-2455, has been active for more than 8 months. We summarise the
transient behaviour of the population to estimate long-term time-averaged
fluxes, and equate these fluxes to the expected mass transfer rate driven by
gravitational radiation in order to constrain the distances. We also estimate
an upper limit of 6 kpc to the distance of IGR J00291+5934 based on the
non-detection of bursts from this source.


title: Alignment tests for low CMB multipoles

abstract:
  We investigate the large scale anomalies in the angular distribution of the
cosmic microwave background radiation as measured by WMAP using several tests.
These tests, based on the multipole vector expansion, measure correlations
between the phases of the multipoles as expressed by the directions of the
multipole vectors and their associated normal planes. We have computed the
probability distribution functions for 46 such tests, for the multipoles l=2-5.
We confirm earlier findings that point to a high level of alignment between l=2
(quadrupole) and l=3 (octopole), but with our tests we do not find significant
planarity in the octopole. In addition, we have found other possible anomalies
in the alignment between the octopole and the l=4 (hexadecupole) components, as
well as in the planarity of l=4 and l=5. We introduce the notion of a total
likelihood to estimate the relevance of the low-multipoles tests of
non-gaussianity. We show that, as a result of these tests, the CMB maps which
are most widely used for cosmological analysis lie within the ~ 10% of randomly
generated maps with lowest likelihoods.


title: Spitzer Observations of High Redshift QSOs

abstract:
  We have observed 13 z >= 4.5 QSOs using the Multiband Imaging Photometer for
Spitzer, nine of which were also observed with the Infrared Array Camera. The
observations probe rest wavelengths ~ 0.6-4.3 micron, bracketing the local
minimum in QSO spectral energy distributions (SEDs) between strong optical
emission associated directly with accretion processes and thermal emission from
hot dust heated by the central engine. The new Spitzer photometry combined with
existing measurements at other wavelengths shows that the SEDs of high redshift
QSOs (z >= 4.5) do not differ significantly from typical QSOs of similar
luminosity at lower redshifts (z <~ 2). This behavior supports other
indications that all the emission components and physical structures that
characterize QSO activity can be established by z = 6.4. The similarity also
suggests that some QSOs at high redshift will be very difficult to identify
because they are viewed along dust-obscured sight lines.


title:
The N2K Consortium VI: Doppler Shifts Without Templates and Three New
  Short-Period Planets

abstract:
  We present a modification to the iodine cell Doppler technique that
eliminates the need for an observed stellar template spectrum. For a given
target star, we iterate toward a synthetic template spectrum beginning with an
existing spectrum of a similar star. We then perturb the shape of this
first-guess template to match the program observation of the target star taken
through an iodine cell. The elimination of a separate template observation
saves valuable telescope time, a feature that is ideally suited for the
quick-look strategy employed by the ``Next 2000 Stars'' (N2K) planet search
program. Tests using Keck/HIRES spectra indicate that synthetic templates yield
a short-term precision of 3 m/s and a long-term, run-to-run precision of 5 m/s.
We used this new Doppler technique to discover three new planets: a 1.5 Mjup
planet in a 2.1375 d orbit around HD 86081; a 0.71 Mjup planet in circular,
26.73 d orbit around HD 224693; and a Saturn-mass planet in an 18.179 d orbit
around HD 33283. The remarkably short period of HD 86081b bridges the gap
between the extremely short-period planets detected in the OGLE survey and the
16 Doppler-detected hot jupiters (P < 15 d), which have an orbital period
distribution that piles up at about three days. We have acquired photometric
observations of two of the planetary host stars with the automated photometric
telescopes at Fairborn Observatory. HD 86081 and HD 224693 both lack detectable
brightness variability on their radial velocity periods, supporting
planetary-reflex motion as the cause of the radial velocity variability. HD
86081 shows no evidence of planetary transits in spite of a 17.6% transit
probability.


title:
Revisiting the characteristics of the spectral lags in short gamma-ray
  bursts

abstract:
  In this paper, we restudy the spectral lag features of short bright gamma-ray
bursts (T90 < 2.6s) with a BATSE time-tagged event (TTE) sample including 65
single pulse bursts. We also make an investigation on the characteristics of
ratios between the spectral lag and the full width at half maximum ($FWHM$) of
the pulses, called relative spectral lags (RSLs). We draw the conclusions as
follows: 1) Spectral lags of short GRBs are normally distributed and
concentrated on around the value of 0.014 with 40 percent of them having
negative lags. With K-S test, we find the lag distribution is identical with a
normal one caused by white noises, which indicates the lags of the vast
majority of short bursts are so small that they are negligible as Norris et al.
have suggested.


title: A New Galactic 6cm Formaldehyde Maser

abstract:
  We report the detection of a new H2CO maser in the massive star forming
region G23.71-0.20 (IRAS 18324-0820), i.e., the fifth region in the Galaxy
where H2CO maser emission has been found. The new H2CO maser is located toward
a compact HII region, and is coincident in velocity and position with 6.7 GHz
methanol masers and with an IR source as revealed by Spitzer/IRAC GLIMPSE data.
The coincidence with an IR source and 6.7 GHz methanol masers suggests that the
maser is in close proximity to an embedded massive protostar. Thus, the
detection of H2CO maser emission toward G23.71-0.20 supports the trend that
H2CO 6cm masers trace molecular material very near young massive stellar
objects.


title:
Detailed Study of the Ursa Major Supercluster of Galaxies Using the
  2MASS and SDSS Catalogs

abstract:
  We study the infrared (K_s band) properties of clusters of galaxies in the
Ursa Major supercluster using data from 2MASS (Two-Micron All-Sky Survey) and
SDSS (Sloan Digital Sky Survey). We identified three large filaments with mean
redshifts of z = 0.051, 0.060, and 0.071. All clusters of the supercluster are
located in these filaments. We determined the total K_s-band luminosities and
masses for 11 clusters of galaxies within comparable physical regions (within a
radius R_200 close to the virial radius) using a homogeneous method. We
constructed a combined luminosity function for the supercluster in this region,
which can be described by the Schechter function with the following parameters:
M*_K = -24^m.50 and \alpha = -0.98. The infrared luminosities of the clusters
of galaxies correlate with their masses; the M/L_K ratios of the systems
increase with their masses (luminosities), with most of the Ursa Major clusters
of galaxies (particularly the richer ones) closely following the relations
derived previously for a large sample of clusters and groups of galaxies. The
total mass-to-infrared-luminosity ratio is 52 M_{\odot}/L_{\odot} for six Abell
clusters and 49 M_{\odot}/L_{\odot} for all of the clusters, except Anon2.


title: A synoptic comparison of the MHD and the OPAL equations of state

abstract:
  A detailed comparison is carried out between two popular equations of state
(EOS), the Mihalas-Hummer-Dappen (MHD) and the OPAL equations of state, which
have found widespread use in solar and stellar modeling during the past two
decades. They are parts of two independent efforts to recalculate stellar
opacities; the international Opacity Project (OP) and the Livermore-based OPAL
project. We examine the difference between the two equations of state in a
broad sense, over the whole applicable rho-T range, and for three different
chemical mixtures. Such a global comparison highlights both their differences
and their similarities.
  We find that omitting a questionable hard-sphere correction, tau, to the
Coulomb interaction in the MHD formulation, greatly improves the agreement
between the MHD and OPAL EOS. We also find signs of differences that could stem
from quantum effects not yet included in the MHD EOS, and differences in the
ionization zones that are probably caused by differences in the mechanisms for
pressure ionization. Our analysis do not only give a clearer perception of the
limitations of each equation of state for astrophysical applications, but also
serve as guidance for future work on the physical issues behind the
differences. The outcome should be an improvement of both equations of state.


title:
Fe K Emission and Absorption in the XMM-EPIC Spectrum of the Seyfert
  Galaxy IC 4329a

abstract:
  We present a detailed analysis of the XMM-Newton long-look of the Seyfert
galaxy IC 4329a. The Fe K bandpass is dominated by two resolved peaks at 6.4
keV and 7.0 keV, consistent with neutral or near-neutral Fe K alpha and K beta
emission. There is a prominent redward asymmetry in the 6.4 keV line, which
could indicate emission from a Compton shoulder. Alternatively, models using
dual relativistic disklines are found to describe the emission profile well. A
low-inclination, moderately-relativistic dual-diskline model is possible if the
contribution from narrow components, due to distant material, is small or
absent. A high-inclination, moderately relativistic profile for each peak is
possible if there are roughly equal contributions from both the broad and
narrow components. Combining the XMM-Newton data with RXTE monitoring data, we
explore the time-resolved spectral behavior on time scales from hours to 2
years. We find no strong evidence for variability of the Fe K line flux on any
time scale, likely due to the minimal level of continuum variability. We
detect, at high significance, a narrow absorption line at 7.68 keV. This
feature is most likely due to Fe XXVI K alpha absorption blueshifted to about
0.1c relative to the systemic velocity, suggesting a high-velocity,
highly-ionized outflow component. As is often the case with similar outflows
seen in high-luminosity quasars, the power associated with the outflow
represents a substantial portion of the total energy budget of the AGN. The
outflow could arise from a radiatively-driven disk wind, or it may be in the
form of a discrete, transient blob of ejected material.


title: A New Milky Way Dwarf Satellite in Canes Venatici

abstract:
  In this Letter, we announce the discovery of a new dwarf satellite of the
Milky Way, located in the constellation Canes Venatici. It was found as a
stellar overdensity in the North Galactic Cap using Sloan Digital Sky Survey
Data Release 5 (SDSS DR5). The satellite's color-magnitude diagram shows a
well-defined red giant branch, as well as a horizontal branch. As judged from
the tip of the red giant branch, it lies at a distance of ~220 kpc. Based on
the SDSS data, we estimate an absolute magnitude of Mv ~ -7.9, a central
surface brightness of mu_0,V ~ 28 mag arcsecond^-2, and a half-light radius of
\~ 8.5' (~ 550 pc at the measured distance). The outer regions of Canes
Venatici appear extended and distorted. The discovery of such a faint galaxy in
proximity to the Milky Way strongly suggests that more such objects remain to
be found.


title: A Faint New Milky Way Satellite in Bootes

abstract:
  In this Letter, we announce the discovery of a new satellite of the Milky Way
in the constellation of Bootes at a distance of 60 kpc. It was found in a
systematic search for stellar overdensities in the North Galactic Cap using
Sloan Digital Sky Survey Data Release 5 (SDSS DR5). The color-magnitude diagram
shows a well-defined turn-off, red giant branch, and extended horizontal
branch. Its absolute magnitude is -5.8, which makes it one of the faintest
galaxies known. The half-light radius is 220 pc. The isodensity contours are
elongated and have an irregular shape, suggesting that Boo may be a disrupted
dwarf spheroidal galaxy.


title: Scalar quantities as detectors of non-Gaussianity on CMB maps

abstract:
  We study the power of several scalar quantities constructed on the sphere
(presented in Monteserin et al. 2005) to detect non-Gaussianity on the
temperature distribution of the cosmic microwave background (CMB). The test has
been performed using non-Gaussian CMB simulations with injected skewness or
kurtosis generated through the Edgeworth expansion. We have also taken into
account in the analysis the effect of anisotropic noise and the presence of a
Galactic mask. We find that the best scalars to detect an excess of skewness in
the simulations are the derivative of the gradient, the fractional isotropy,
the Laplacian and the shape index. For the kurtosis case, the fractional
anisotropy, the Laplacian and the determinant are the quantities that perform
better.


title:
The AGN Outflow in the HDFS Target QSO J2233-606 from a High-Resolution
  VLT/UVES Spectrum

abstract:
  We present a detailed analysis of the intrinsic UV absorption in the central
HDFS target QSO J2233-606, based on a high-resolution, high S/N (~25 -- 50)
spectrum obtained with VLT/UVES. This spectrum samples the cluster of intrinsic
absorption systems outflowing from the AGN at radial velocities v ~ -5000 --
-3800 km/s in the key far-UV diagnostic lines - the lithium-like CNO doublets
and H I Lyman series. We fit the absorption troughs using a global model of all
detected lines to solve for the independent velocity-dependent covering factors
of the continuum and emission-line sources and ionic column densities. This
reveals increasing covering factors in components with greater outflow
velocity. Narrow substructure is revealed in the optical depth profiles,
suggesting the relatively broad absorption is comprised of a series of multiple
components. We perform velocity-dependent photoionization modeling, which
allows a full solution to the C, N, and O abundances, as well as the velocity
resolved ionization parameter and total column density. The absorbers are found
to have supersolar abundances, with [C/H] and [O/H] ~0.5 -- 0.9, and [N/H] ~
1.1 -- 1.3, consistent with enhanced nitrogen production expected from
secondary nucleosynthesis processes. Independent fits to each kinematic
component give consistent results for the abundances. The lowest-ionization
material in each of the strong absorbers is modeled with similar ionization
parameters. Components of higher-ionization (indicated by stronger O VI
relative to C IV and N V) are present at velocities just redward of each
low-ionization absorber. We explore the implications of these results for the
kinematic-geometric-ionization structure of the outflow.


title: Galaxy surveys, inhomogeneous reionization, and dark energy

abstract:
  We examine the effect of inhomogeneous reionization on the galaxy power
spectrum and the consequences for probing dark energy. To model feedback during
reionization, we apply an ansatz setting the galaxy overdensity proportional to
the underlying ionization field. Thus, inhomogeneous reionization may leave an
imprint in the galaxy power spectrum. We evolve this imprint to low redshift
and use the Fisher-matrix formalism to assess the effect on parameter
estimation. We show that a combination of low- (z=0.3) and high- (z=3) redshift
galaxy surveys can constrain the size of cosmological HII regions during
reionization. This imprint can also cause confusion when using baryon
oscillations or other features of the galaxy power spectrum to probe the dark
energy. We show that when bubbles are large, and hence detectable, our ability
to constrain w can be degraded by up to 50%. When bubbles are small, the
imprint has little or no effect on measuring dark-energy parameters.


title:
The QUEST RR Lyrae Survey II: The Halo Overdensities in the First
  Catalog

abstract:
  The first catalog of the RR Lyrae stars (RRLS) in the Galactic halo by the
QUEST Survey has been searched for significant overdensities that may be debris
from disrupted dwarf galaxies or globular clusters. Away from the major
overdensities, the distribution of these stars is adequately fit by a smooth
halo model, in which the flattening of the halo decreases with increasing
galactocentric distance (Preston et al 1991). This model was used to estimate
the ``background'' of RRLS on which the halo overdensities are overlaid. A
procedure was developed for recognizing groups of stars that constitute
significant overdensities with respect to this background. To test this
procedure, a Monte Carlo routine was used to make artificial RRLS surveys that
follow the smooth halo model, but with Poisson distributed noise in the numbers
of RRLS and, within limits, random variations in the positions and magnitudes
of the artificial stars. The artificial surveys created by this routine were
examined for significant groups in exactly the same way as the QUEST survey.
These calculations provided estimates of the frequencies with which random
fluctuations produce significant groups. In the QUEST survey, there are six
significant overdensities that contain six or more stars and several smaller
ones. The small ones and possibly one or two of the larger ones may be
artifacts of statistical fluctuations, and they need to be confirmed by
measurements of radial velocity and/or proper motion. The most prominent groups
are the northern stream from the Sagittarius dwarf spheroidal galaxy and a
large group in Virgo. Two other groups lie in the direction of the Monoceros
stream and at approximately the right distance for membership. Another group is
related to the globular cluster Palomar 5.


title: Smooth Particle Lensing

abstract:
  We present a numerical technique to compute the gravitational lensing induced
by simulated haloes. It relies on a 2D-Tree domain decomposition in the lens
plane combined with a description of N-Body particles as extended clouds with a
non-singular density. This technique is made fully adaptive by the use of a
density-dependent smoothing which allows one to probe the lensing properties of
haloes from the densest regions in the center or in substructures to the
low-density regions in the outskirts. 'Smooth Particle Lensing' has some
promising features. First, the deflection potential, the deflection angles, the
convergence and the shear are direct and separate end-products of the SPL
calculation and can be computed at an arbitrary distribution of points on the
lens plane. Second, this flexibility avoids the use of interpolation or a
finite differentiation procedure on a grid, does not require padding the region
with zeros and focuses the computing power on relevant regions. The SPL
algorithm is tested by populating isothermal spheres and ellipsoids with
particles and then comparing the lensing calculations to the classical
FFT-based technique and analytic solutions. We assess issues related to the
resolution of the lensing code and the limitations set by the simulations
themselves. We conclude by discussing how SPL can be used to predict the impact
of substructures on strong lensing and how it can be generalized to weak
lensing and cosmic shear simulations.


title:
On the Robustness of the Acoustic Scale in the Low-Redshift Clustering
  of Matter

abstract:
  We discuss the effects of non-linear structure formation on the signature of
acoustic oscillations in the late-time galaxy distribution. We argue that the
dominant non-linear effect is the differential motion of pairs of tracers
separated by 150 Mpc. These motions are driven by bulk flows and cluster
formation and are much smaller than the acoustic scale itself. We present a
model for the non-linear evolution based on the distribution of pairwise
Lagrangian displacements that provides a quantitative model for the degradation
of the acoustic signature, even for biased tracers in redshift space. The
Lagrangian displacement distribution can be calibrated with a significantly
smaller set of simulations than would be needed to construct a precise power
spectrum. By connecting the acoustic signature in the Fourier basis with that
in the configuration basis, we show that the acoustic signature is more robust
than the usual Fourier-space intuition would suggest because the beat frequency
between the peaks and troughs of the acoustic oscillations is a very small
wavenumber that is well inside the linear regime. We argue that any possible
shift of the acoustic scale is related to infall on 150 Mpc scale, which is
O(0.5%) fractionally at first-order even at z=0. For the matter, there is a
first-order cancellation such that the mean shift is O(10^{-4}). However,
galaxy bias can circumvent this cancellation and produce a sub-percent
systematic bias.


title:
Improving Cosmological Distance Measurements by Reconstruction of the
  Baryon Acoustic Peak

abstract:
  The baryon acoustic oscillations are a promising route to the precision
measure of the cosmological distance scale and hence the measurement of the
time evolution of dark energy. We show that the non-linear degradation of the
acoustic signature in the correlations of low-redshift galaxies is a
correctable process. By suitable reconstruction of the linear density field,
one can sharpen the acoustic peak in the correlation function or, equivalently,
restore the higher harmonics of the oscillations in the power spectrum. With
this, one can achieve better measurements of the acoustic scale for a given
survey volume. Reconstruction is particularly effective at low redshift, where
the non-linearities are worse but where the dark energy density is highest. At
z=0.3, we find that one can reduce the sample variance error bar on the
acoustic scale by at least a factor of 2 and in principle by nearly a factor of
4. We discuss the significant implications our results have for the design of
galaxy surveys aimed at measuring the distance scale through the acoustic peak.


title:
Collisional Ionization Equilibrium for Optically Thin Plasmas. I.
  Updated Recombination Rate Coefficients for Bare though Sodium-like Ions

abstract:
  Reliably interpreting spectra from electron-ionized cosmic plasmas requires
accurate ionization balance calculations for the plasma in question. However,
much of the atomic data needed for these calculations have not been generated
using modern theoretical methods and are often highly suspect. This translates
directly into the reliability of the collisional ionization equilibrium (CIE)
calculations. We make use of state-of-the-art calculations of dielectronic
recombination (DR) rate coefficients for the hydrogenic through Na-like ions of
all elements from He up to and including Zn. We also make use of
state-of-the-art radiative recombination (RR) rate coefficient calculations for
the bare through Na-like ions of all elements from H through to Zn. Here we
present improved CIE calculations for temperatures from $10^4$ to $10^9$ K
using our data and the recommended electron impact ionization data of
\citet{Mazz98a} for elements up to and including Ni and Mazzotta (private
communication) for Cu and Zn. DR and RR data for ionization stages that have
not been updated are also taken from these two additional sources. We compare
our calculated fractional ionic abundances using these data with those
presented by Mazzotta et al. for all elements from H to Ni. The differences in
peak fractional abundance are up to 60%. We also compare with the fractional
ionic abundances for Mg, Si, S, Ar, Ca, Fe, and Ni derived from the modern DR
calculations of \citet{Gu03a,Gu04a} for the H-like through Na-like ions, and
the RR calculations of \citet{Gu03b} for the bare through F-like ions. These
results are in better agreement with our work, with differences in peak
fractional abundance of less than 10%.


title: Force-Free Electrodynamics of Pulsars

abstract:
  We show that FFE (Force-Free Electrodynamics) describes pulsar magnetospheres
-- even when radiation and particle wind power are comparable to the spin-down
power. At the same time, we show that FFE is insufficient for calculating
pulsar magnetospheres. This is because FFE admits a large family of stationary
solutions with different currents flowing in the closed line region. To choose
the actual solution one needs a model of current generation which goes beyond
pure FFE.
  We calculate several FFE magnetospheres for the aligned rotator. The Poynting
power of these solutions fills the range $c^{-3}\mu ^2\Omega^4~< ~L~ <~ 0.67
c^{-3}\mu ^2\Omega^4(c/\Omega R_s)^2$, for angular velocity $\Omega$ and
magnetic field which is a pure dipole $\mu$ on the surface of the star of
radius $R_s$.
  Anomalous braking indices of young pulsars might be explained by currents
flowing in the closed-line region.


title:
Design and Performance of the Soft Gamma-ray Detector for the NeXT
  mission

abstract:
  The Soft Gamma-ray Detector (SGD) on board the NeXT (Japanese future high
energy astrophysics mission) is a Compton telescope with narrow field of view
(FOV), which utilizes Compton kinematics to enhance its background rejection
capabilities. It is realized as a hybrid semiconductor gamma-ray detector which
consists of silicon and CdTe (cadmium telluride) detectors. It can detect
photons in a wide energy band (0.05-1 MeV) at a background level of 5 x 10^-7
counts/cm^2/s; the silicon layers are required to improve the performance at a
lower energy band (<0.3 MeV). Excellent energy resolution is the key feature of
the SGD, allowing it to achieve both high angular resolution and good
background rejection capability. An additional capability of the SGD, its
ability to measure gamma-ray polarization, opens up a new window to study
properties of astronomical objects. We will present the development of key
technologies to realize the SGD: high quality CdTe, low noise front-end ASIC
and bump bonding technology. Energy resolutions of 1.7 keV (FWHM) for CdTe
pixel detectors and 1.1 keV for Si strip detectors have been measured. We also
present the validation of Monte Carlo simulation used to evaluate the
performance of the SGD.


title: Analysis of White Dwarfs with Strange-Matter Cores

abstract:
  We summarize masses and radii for a number of white dwarfs as deduced from a
combination of proper motion studies, Hipparcos parallax distances, effective
temperatures, and binary or spectroscopic masses. A puzzling feature of these
data is that some stars appear to have radii which are significantly smaller
than that expected for a standard electron-degenerate white-dwarf equations of
state. We construct a projection of white-dwarf radii for fixed effective mass
and conclude that there is at least marginal evidence for bimodality in the
radius distribution forwhite dwarfs. We argue that if such compact white dwarfs
exist it is unlikely that they contain an iron core. We propose an alternative
of strange-quark matter within the white-dwarf core. We also discuss the impact
of the so-called color-flavor locked (CFL) state in strange-matter core
associated with color superconductivity. We show that the data exhibit several
features consistent with the expected mass-radius relation of strange dwarfs.
We identify eight nearby white dwarfs which are possible candidates for strange
matter cores and suggest observational tests of this hypothesis.


title: Two populations of metal-free stars in the early Universe

abstract:
  We construct star formation histories at redshifts z > 5 for two physically
distinct populations of primordial, metal-free stars, motivated by theoretical
and observational arguments that have hinted towards the existence of an
intermediate stellar generation between Population III and Population I/II.
Taking into account the cosmological parameters as recently revised by WMAP
after three years of operation, we determine self-consistent reionization
histories and discuss the resulting chemical enrichment from these early
stellar generations. We find that the bulk of ionizing photons and heavy
elements produced at high redshifts must have originated in Population II.5
stars, which formed out of primordial gas in haloes with virial temperatures >=
10^4 K, and had typical masses >= 10 M_sun. Classical Population III stars,
formed in minihaloes and having masses >= 100 M_sun, on the other hand, had
only a minor impact on reionization and early metal enrichment. Specifically,
we find that only 10 per cent by mass of metal-free star formation went into
Population III.


title: What is special about HBRPs

abstract:
  The Parkes Multibeam Survey led to the identification ofa number of
long-period radio pulsars with magnetic field well above the quantum critical
field of 4.4 times 10 to 13 G (defined as high magnetic field radio pulsars -
HBRPs). Traditional pulsar emission theories postulate that radio emission is
suppressed above this critical field. The aim of thisproject is to understand
emission properties of HBRPs.


title: Unusual PAH Emission in Elliptical Galaxies

abstract:
  In a sample of thirty normal elliptical galaxies observed with the Spitzer
IRS, one galaxy, NGC4697, shows strong PAH emission, but with an apparently
weak 7.7 micron feature. We find that the PAH emission is confined to the
central regions of the galaxy and that once a quiescent elliptical galaxy
spectrum is subtracted, the PAH feature ratios are normal. We show that the PAH
spectrum resembles the diffuse ISM of our galaxy rather than an HII region, and
is not indicative of a starburst galaxy. We suggest that the PAHs in NGC4697
are consistent with a recent but now past burst of star formation.


title:
Neutrino-Dominated Accretion Models for Gamma-Ray Bursts: Effects of
  General Relativity and Neutrino Opacity

abstract:
  We first refine the fixed concept in the literature that the usage of the
Newtonian potential in studies of black hole accretion is invalid and the
general relativistic effect must be considered. As our main results, we then
show that the energy released by neutrino annihilation in neutrino-dominated
accretion flows is sufficient for gamma-ray bursts when the contribution from
the optically thick region of the flow is included, and that in the optically
thick region advection does not necessarily dominate over neutrino cooling
because the advection factor is relevant to the geometrical depth rather than
the optical depth of the flow.


title: A Time-Symmetric Block Time-Step Algorithm for N-Body Simulations

abstract:
  The method of choice for integrating the equations of motion of the general
N-body problem has been to use an individual time step scheme. For the sake of
efficiency, block time steps have been the most popular, where all time step
sizes are smaller than a maximum time step size by an integer power of two. We
present the first successful attempt to construct a time-symmetric integration
scheme, based on block time steps. We demonstrate how our scheme shows a vastly
better long-time behavior of energy errors, in the form of a random walk rather
than a linear drift. Increasing the number of particles makes the improvement
even more pronounced.


title:
Bright OB stars in the Galaxy - III. Constraints on the radial
  stratification of the clumping factor in hot star winds from a combined
  Halpha, IR and radio analysis

abstract:
  Recent results strongly challenge the canonical picture of massive star
winds: various evidence indicates that currently accepted mass-loss rates,
Mdot, may need to be revised downwards significantly. This is because the most
commonly used mass-loss diagnostics are affected by ``clumping'' (small-scale
density inhomogeneities), influencing our interpretation of observed spectra
and fluxes. Such downward revisions would have dramatic consequences for the
evolution of, and feedback from, massive stars, and thus robust determinations
of the clumping properties and mass-loss rates are urgently needed. Here, we
present a first attempt to constrain the radial stratification of the so-called
clumping factor. To this end, we have analyzed a sample of 19 Galactic O-type
supergiants/giants, by combining data for Halpha, IR, mm and radio fluxes, and
using appropriate analysis methods. Clumping has been included into our
analysis in the ``conventional'' way, by assuming the inter-clump matter to be
void. Because (almost) all our diagnostics depends on the square of density, we
cannot derive absolute clumping factors, but only factors normalized to a
certain minimum. This minimum was usually found to be located in the outermost,
radio-emitting region, i.e., the radio mass-loss rates are the lowest ones,
compared to Mdot derived from Halpha and the IR. The radio rates agree well
with those predicted by theory, but are only upper limits, due to unknown
clumping in the outer wind. Our most important result concerns a (physical)
difference between denser and thinner winds: for denser winds, the innermost
region is more strongly clumped than the outermost one (with a normalized
clumping factor of 4.1+/-1.4), whereas thinner winds have similar clumping
properties in the inner and outer regions.


title: The z=3 QSO Luminosity Function with SWIRE

abstract:
  We use a simple optical/infrared photometric selection of high redshift QSOs
which identifies a Lyman Break in the optical and requires a red IRAC color to
distinguish QSOs from common interlopers. We find 100 U-dropout (z=3) QSO
candidates with r'<22 within 11.2 deg^2 in the ELAIS-N1 & ELAIS-N2 fields in
the Spitzer Wide-Area Infrared Extragalactic (SWIRE) Legacy Survey.
Spectroscopy of 10 candidates shows that they are all QSOs with 2.83<z<3.44. We
use detailed simulations which incorporate variations in QSO SEDs, IGM
transmission and imaging depth to derive a completeness of 85-90% between
3.0<z<3.4. The resulting luminosity function is two magnitudes fainter than
SDSS and, when combined with those data, gives a faint end slop \beta = 1.62
\pm 0.18, consistent with measurements at z<2 and steeper than initial
measurements at the same redshift.


title: From AMANDA to IceCube

abstract:
  The success of the AMANDA neutrino telescope has shown that the ice sheet at
the geographical South Pole is a suitable medium for optical Cherenkov
detection of high energy neutrino interactions. Several thousands of
atmospheric neutrinos have been recorded by AMANDA and the sensitivity for
cosmic neutrinos has continuously improved. So far no cosmic neutrino signals
have been detected. The deployment of the much larger and more sensitive
IceCube neutrino observatory has started and nine out of 80 strings have been
installed. This paper summarizes some of the results obtained by the AMANDA
telescope and presents the status of the IceCube project.


title: Do mean-field dynamos in nonrotating turbulent shear-flows exist?

abstract:
  A plane-shear flow in a fluid with forced turbulence is considered. If the
fluid is electrically-conducting then a mean electromotive force (EMF) results
even without basic rotation and the magnetic diffusivity becomes a highly
anisotropic tensor. It is checked whether in this case self-excitation of a
large-scale magnetic field is possible (so-called WxJ-dynamo) and the answer is
NO. The calculations reveal the cross-stream components of the EMF
perpendicular to the mean current having the wrong signs, at least for small
magnetic Prandtl numbers. After our results numerical simulations with magnetic
Prandtl number of about unity have only a restricted meaning as the Prandtl
number dependence of the diffusivity tensor is rather strong. If, on the other
hand, the turbulence field is stratified in the vertical direction then a
dynamo active alpha-effect is produced. The critical magnetic Reynolds number
for such a self-excitation in a simple shear flow is slightly above 10 like for
the other - but much more complicated - flow patterns used in existing dynamo
experiments with liquid sodium or gallium.


title:
The Mexican Hat Wavelet Family. Application to point source detection in
  CMB maps

abstract:
  We propose a new detection technique in the plane based on an isotropic
wavelet family. This family is naturally constructed as an extension of the
Gaussian-Mexican Hat Wavelet pair and for that reason we call it the Mexican
Hat Wavelet Family (MHWF). We show the performance of these wavelets when
dealing with the detection of extragalactic point sources in cosmic microwave
background (CMB) maps: a very important issue within the most general problem
of the component separation of the microwave sky. Specifically, flat
two-dimensional simulations of the microwave sky comprising all astrophysical
components plus instrumental noise have been analyzed for the channels at 30,
44 and 70 GHz of the forthcoming ESA's Planck mission Low Frequency Instrument
(LFI). We adopt up-to-date cosmological evolution models of extragalactic
sources able to fit well the new data on high-frequency radio surveys and we
discuss our current results on point source detection by comparing them with
those obtained using the Mexican Hat Wavelet (MHW) technique, which has been
already proven a suitable tool for detecting point sources. By assuming a 5%
reliability level, the first new members of the MHWF, at their ``optimal
scale'', provide three point source catalogues on half of the sky (at galactic
latitude |b|> 30) at 30, 44 and 70 GHz of 639, 387 and 340 extragalactic
sources, respectively. The corresponding flux detection limits are 0.38, 0.45
and 0.47 Jy . By using the same simulated sky patches and at the same
frequencies as before, the MHW at its optimal scale provides 543, 322 and 311
sources with flux detection limits of 0.44, 0.51 and 0.50 Jy, respectively (5%
reliability level). These results show a clear improvement when we use the new
members of the MHWF and, in particular, the MHW2 with respect to the MHW.


title:
The origin of the hot metal-poor gas in NGC1291: Testing the hypothesis
  of gas dynamics as the cause of the gas heating

abstract:
  In this paper we test the idea that the low-metallicity hot gas in the centre
of NGC 1291 is heated via a dynamical process. In this scenario, the gas from
the outer gas-rich ring loses energy through bar-driven shocks and falls to the
centre. Heating of the gas to X-ray temperatures comes from the high velocity
that it reaches ($\approx$ 700 \kms) as it falls to the bottom of the potential
well. This would explain why the stellar metallicity in the bulge region is
around solar while the hot gas metallicity is around 0.1 solar. We carried out
an observational test to check this hypothesis by measuring the metallicity of
HII regions in the outer ring to check whether they matched the hot gas
metallicity. For this purpose we obtained medium resolution long slit
spectroscopy with FORS1 on the ESO VLT at Paranal and obtained the
metallicities using emission line ratio diagnostics. The obtained metallicities
are compatible with the bulge stellar metallicities but very different from the
hot-gas metallicity. However, when comparing the different time-scales, the gas
in the ring had time enough to get enriched through stellar processes,
therefore we cannot rule out the dynamical mechanism as the heating process of
the gas. However, the blue colours of the outer ring and the dust structures in
the bar region could suggest that the origin of the X-ray hot gas is due to the
infall of material from further out.


title:
Strange magnification pattern in the large separation lens SDSS
  J1004+4112 from optical to X-rays

abstract:
  We present simultaneous XMM-Newton UV and X-ray observations of the quadruply
lensed quasar SDSS J1004+4112 (RBS 825). Simultaneously with the XMM-Newton
observations we also performed integral field spectroscopy on the two closest
lens images A and B using the Calar Alto PMAS spectrograph. In X-rays the
widely spaced components C and D are clearly resolved, while the closer pair of
images A and B is marginally resolved in the XMM-EPIC images. The integrated
X-ray flux of the system has decreased by a factor of 6 since it was observed
in the ROSAT All Sky Survey in 1990, while the X-ray spectrum became much
harder with the power law index evolving from Gamma=-2.3 to -1.86. By
deblending the X-ray images of the lensed QSO we find that the X-ray flux
ratios between the lens images A and B are significantly different from the
simultaneously obtained UV ratios and previously measured optical flux ratios.
Our optical spectrum of lens image A shows an enhancement in the blue emission
line wings, which has been observed in previous epochs as a transient feature.
We propose a scenario where intrinsic UV and X-ray variability gives rise to
line variations which are selectively magnified in image A by microlensing. The
extended emission of the lensing cluster of galaxies is clearly detected in the
EPIC images, we measure a 0.5-2.0 keV luminosity of 1.4 E44 erg/s. Based on the
cluster X-ray properties, we estimate a mass of 2-6 E14 solar masses.


title: Flux predictions of high-energy neutrinos from pulsars

abstract:
  Young, rapidly rotating neutron stars could accelerate ions from their
surface to energies of $\sim 1$ PeV. If protons reach such energies, they will
produce pions (with low probability) through resonant scattering with x-rays
from the stellar surface. The pions subsequently decay to produce muon
neutrinos. Here we calculate the energy spectrum of muon neutrinos, and
estimate the event rates at Earth. The spectrum consists of a sharp rise at
$\sim 50$ TeV, corresponding to the onset of the resonance, above which the
flux drops with neutrino energy as $\epsilon_\nu^{-2}$ up to an upper-energy
cut-off that is determined by either kinematics or by the maximum energy to
which protons are accelerated. We estimate event rates as high as 10-100
km^${-2}$ yr$^{-1}$ from some candidates, a flux that would be easily detected
by IceCube. Lack of detection would allow constraints on the energetics of the
poorly-understood pulsar magnetosphere.


title:
Scaling Law for the Magnetic Field of the Planets Based on a
  Thermodynamic Model

abstract:
  A thermodynamic model for the generation of magnetic fields in the planets is
proposed, considering crossed effects between gravitational and electric
forces. The magnetic field of the Earth is estimated and found to be in
agreement with the actual field. The ratio between the field of several planets
and that of the Earth is calculated in the model and compared with the same
ratio for the measured fields. These comparisons are found to be qualitatively
consistent. Once the value of the magnetic field is calculated, the model is
used to obtain the tilt of the magnetic dipole with respect to the rotation
axis. This model can explain why Uranus and Neptune magnetic fields have higher
quadrupole moment than the other magnetic fields of the Solar System and why
Saturn, that has a highly axysymmetric field, has lower quadrupolar component.
The model also explains the double peak of the magnetic field observed by
Voyager 2 while recording the field of Neptune. The Earth paleomagnetic data
are analysed and found to be consistent with the model, that predicts higher
quadrupole components for the more tilted dipoles. A field is predicted for all
the planets and satellites of the Solar System with enough mass. Objections are
made to the theories that predict that this effect could not generate a field
agreeing with the measured one.


title:
Quiet Sun magnetic fields from simultaneous inversions of visible and
  infrared spectropolarimetric observations

abstract:
  We study the quiet Sun magnetic fields using spectropolarimetric observations
of the infrared and visible Fe I lines at 6301.5, 6302.5, 15648 and 15653 A.
Magnetic field strengths and filling factors are inferred by the simultaneous
fit of the observed Stokes profiles under the MISMA hypothesis. The
observations cover an intra-network region at the solar disk center. We analyze
2280 Stokes profiles whose polarization signals are above noise in the two
spectral ranges, which correspond to 40% of the field of view. Most of these
profiles can be reproduced only with a model atmosphere including 3 magnetic
components with very different field strengths, which indicates the
co-existence of kG and sub-kG fields in our 1.5" resolution elements. We
measure an unsigned magnetic flux density of 9.6 G considering the full field
of view. Half of the pixels present magnetic fields with mixed polarities in
the resolution element. The fraction of mixed polarities increases as the
polarization weakens. We compute the probability density function of finding
each magnetic field strength. It has a significant contribution of kG field
strengths, which concentrates most of the observed magnetic flux and energy.
This kG contribution has a preferred magnetic polarity, while the polarity of
the weak fields is balanced.


title:
A population of high-redshift type-2 quasars-I. Selection Criteria and
  Optical Spectra

abstract:
  We discuss the relative merits of mid-infrared and X-ray selection of type-2
quasars. We describe the mid-infrared, near-infrared and radio selection
criteria used to find a population of redshift z~2 type-2 quasars which we
previously argued suggests that most supermassive black hole growth in the
Universe is obscured (Martinez-Sansigre et al., 2005). We present the optical
spectra obtained from the William Herschel Telescope, and we compare the narrow
emission line luminosity, radio luminosity and maximum size of jets to those of
objects from radio-selected samples. This analysis suggests that these are
genuine radio-quiet type-2 quasars, albeit the radio-bright end of this
population. We also discuss the possibility of two different types of quasar
obscuration, which could explain how the ~2-3:1 ratio of type-2 to type-1
quasars preferred by modelling our population can be reconciled with the ~1:1
ratio predicted by unified schemes.


title:
Deep GMOS Spectroscopy of Extremely Red Galaxies in GOODS-South:
  Ellipticals, Mergers and Red Spirals at 1<z<2

abstract:
  We have performed a deep spectroscopic survey of extremely red galaxies on
the GOODS-South field, using GMOS on Gemini South. We present here spectra and
redshifts for 16 ERGs at 0.87<z<2.02, to a limit K=20.2. The ERHs are a mixture
of spheroidals, mergers and spirals, with one AGN. For at least 10 of these
galaxies we observe [OII] emission lines. We perform an age-dating analysis by
fitting the spectra and 9-band photometry of the ERGs with models of passively
evolving stellar populations combined with a younger star-forming component.
The best-fitting ages for the old stellar components range from 0.6 to 4.5 Gyr,
with a mean 2.1 Gyr. Masses range from 3 to 20 times 10^10 solar masses. The
star-forming component typically forms a few per cent of the total mass, with
dust reddening averaging E(B-V)=0.35. Its timescale tends to be short for
mergers (<50 Myr) and longer (200-800 Myr) for spiral ERGs.


title: Star Formation in the Era of the Three Great Observatories

abstract:
  This paper summarizes contributions and suggestions as presented at the
Chandra Workshop Star Formation in the Era of Three Great Observatories
conducted in July 2005. One of the declared goals of the workshop was to raise
recognition within the star formation research community about the sensible
future utilization of the space observatories Spitzer, Hubble, and Chandra in
their remaining years of operation to tackle imminent questions of our
understanding of stellar formation and the early evolution of stars. A white
paper was generated to support the continuous and simultaneous usage of
observatory time for star formation research. The contents of this paper have
been presented and discussed at several other meetings during the course of
2005 and January 2006.


title:
Automated derivation of stellar atmospheric parameters and chemical
  abundances: the MATISSE algorithm

abstract:
  We present an automated procedure for the derivation of atmospheric
parameters (Teff, log g, [M/H]) and individual chemical abundances from stellar
spectra. The MATrix Inversion for Spectral SythEsis (MATISSE) algorithm
determines a basis, B_\theta(\lambda), allowing to derive a particular stellar
parameter \theta by projection of an observed spectrum. The B_\theta(\lambda)
function is determined from an optimal linear combination of theoretical
spectra and it relates, in a quantitative way, the variations in the spectrum
flux with variations in \theta. An application of this method to the GAIA/RVS
spectral range is described, together with its performances for different types
of stars of various metallicities. Blind tests with synthetic spectra of
randomly selected parameters and observed input spectra are also presented. The
method gives rapid, accurate and stable results and it can be efficiently
applied to the study of stellar populations through the analysis of large
spectral data sets, including moderate to low signal to noise spectra.


title: Magnetars' Giant Flares: the case of SGR 1806-20

abstract:
  We first review on the peculiar characteristics of the bursting and flaring
activity of the Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars. We then
report on the properties of the SGR 1806-20's Giant Flare occurred on 2004
December 27th, with particular interest on the pre and post flare
intensity/hardness correlated variability. We show that these findings are
consistent with the picture of a twisted internal magnetic field which stresses
the star solid crust that finally cracks causing the giant flare (and the
observed torsional oscillations). This crustal fracturing is accompanied by a
simplification of the external magnetic field with a (partial) untwisting of
the magnetosphere.


title: A numerical study of non-gaussianity in the curvaton scenario

abstract:
  We study the curvaton scenario using gauge-invariant second order
perturbation theory and solving the governing equations numerically. Focusing
on large scales we calculate the non-linearity parameter f_nl in the two-fluid
curvaton model and compare our results with previous analytical studies
employing the sudden decay approximation. We find good agreement of the two
approaches for large curvaton energy densities at curvaton decay, Omega_dec,
but significant differences of up to 10 percent for small Omega_dec.


title:
H-alpha Observations of a Large Sample of Galaxies at z~2: Implications
  for Star Formation in High Redshift Galaxies

abstract:
  Using H-alpha spectra of 114 rest-frame UV-selected galaxies at z~2, we
compare inferred star formation rates (SFRs) with those determined from the UV
continuum luminosity. After correcting for extinction using standard techniques
based on the UV continuum slope, we find excellent agreement between the
indicators, with <SFR_Ha> = 31 Msun/yr and <SFR_UV> = 29 Msun/yr. The agreement
between the indicators suggests that the UV luminosity is attenuated by an
typical factor of ~4.5 (with a range from no attenuation to a factor of ~100
for the most obscured object in the sample), in good agreement with estimates
of obscuration from X-ray, radio and mid-IR data. The H-alpha luminosity is
attenuated by a factor of ~1.7 on average, and the maximum H-alpha attenuation
is a factor of ~5. In agreement with X-ray and mid-IR studies, we find that the
SFR increases with increasing stellar mass and at brighter K magnitudes, to
<SFR_Ha> ~ 60 Msun/yr for galaxies with K<20; the correlation between K
magnitude and SFR is much stronger than the correlation between stellar mass
and SFR. All galaxies in the sample have SFRs per unit area Sigma_SFR in the
range observed in local starbursts. We compare the instantaneous SFRs and the
past average SFRs as inferred from the ages and stellar masses, finding that
for most of the sample, the current SFR is an adequate representation of the
past average. There is some evidence that the most massive galaxies (M_star
>10^11 Msun) have had higher SFRs in the past.


title: Relativistic ejecta from XRF 060218 and the rate of cosmic explosions

abstract:
  Over the last decade, long-duration gamma-ray bursts (GRBs) including the
subclass of X-ray flashes (XRFs) have been revealed to be a rare variety of
Type Ibc supernova (SN). While all these events result from the death of
massive stars, the electromagnetic luminosities of GRBs and XRFs exceed those
of ordinary Type Ibc SNe by many orders of magnitude. The essential physical
process that causes a dying star to produce a GRB or XRF, and not just an SN,
remains the crucial open question. Here we present radio and X-ray observations
of XRF 060218 (associated with SN 2006aj), the second nearest GRB identified
to-date, which allow us to measure its total energy and place it in the larger
context of cosmic explosions. We show that this event is 100 times less
energetic but ten times more common than cosmological GRBs. Moreover, it is
distinguished from ordinary Type Ibc SNe by the presence of 10^48 erg coupled
to mildly-relativistic ejecta, along with a central engine (an accretion-fed,
rapidly rotating compact source) which produces X-rays for weeks after the
explosion. This suggests that the production of relativistic ejecta is the key
physical distinction between GRBs/XRFs and ordinary SNe, while the nature of
the central engine (black hole or magnetar) may distinguish typical bursts from
low-luminosity, spherical events like XRF 060218.


title:
The Formation Epoch of Early-Type Galaxies in the z ~ 0.9 CL1604
  Supercluster

abstract:
  We analyse the cluster color-magnitude relation (CMR) for early-type galaxies
in two of the richer clusters in the z ~ 0.9 supercluster system to derive
average ages and formation redshifts for the early-type galaxy population. Both
clusters were observed with the Advanced Camera for Surveys aboard the {\it
Hubble Space Telescope} through the F606W and F814W filters, which brackets the
rest-frame 4000 \AA break at the cluster redshifts of z\sim 0.9. We fit the
zeropoint and slope of the red cluster sequence, and model the scatter about
this relation to estimate average galaxy ages and formation redshifts. We find
intrinsic scatters of 0.038-0.053 mag in ($V_{606}-I_{814}$) for the E and E+S0
populations, corresponding to average ages of 3.5-3.7 Gyr and formation
redshifts z_{f}=2.4-2.6. We find at least one significant difference between
the Cl1604+4304 and Cl1604+4321 early-type CMRs. Cl1604+4321, the less X-ray
luminous and massive of the two, lacks bright L^* ellipticals. We combine the
galaxy samples to fit a composite CMR down to 0.15L^*, and find that the slope
of the combined cluster CMR is significantly steeper than for RX J0152.7-1357
but consistent with MS 1054-03, both at similar redshift. The slope of the
Cl1604 CMR at the bright end (L > 0.5L^*) is flatter and consistent with the
CMR slopes found for other high redshift clusters. We find evidence for
increasing scatter with increasing magnitude along the early-type CMR,
consistent with a 'downsizing' scenario, indicating younger mean ages with
decreasing galaxy mass.


title: Comparing Dynamical and Stellar Population Mass-to-Light Ratio Estimates

abstract:
  We investigate the mass-to-light ratios of stellar populations as predicted
by stellar population synthesis codes and compare those to
dynamical/gravitational measurements. In Bell & de Jong (2001) we showed that
population synthesis models predict a tight relation between the color and
mass-to-light ratio of a stellar population. The normalization of this relation
depends critically on the shape of the stellar IMF at the low-mass end. These
faint stars contribute significantly to the mass, but insignificantly to the
luminosity and color of a stellar system. In Bell & de Jong (2001) we used
rotation curves to normalize the relation, but rotation curves provide only an
upper limit to the stellar masses in a system. Here we compare stellar and
dynamical masses for a range of stellar systems in order to constrain the mass
normalization of stellar population models. We find that the normalization of
Bell & de Jong (2001) should be lowered by about 0.05-0.1 dex in M/L. This is
consistent with a Kroupa (2001), Chabrier (2003) or a Kennicutt (1983) IMF, but
does not leave much room for other unseen components.


title: Arecibo and the ALFA Pulsar Survey

abstract:
  The recently started Arecibo L-band Feed Array (ALFA) pulsar survey aims to
find ~1000 new pulsars. Due to its high time and frequency resolution the
survey is especially sensitive to millisecond pulsars, which have the potential
to test gravitational theories, detect gravitational waves and probe the
neutron-star equation of state. Here we report the results of our preliminary
analysis: in the first months we have discovered 21 new pulsars. One of these,
PSR J1906+0746, is a young 144-ms pulsar in a highly relativistic 3.98-hr
low-eccentricity orbit. The 2.61 +- 0.02 solar-mass system is expected to
coalesce in ~300 Myr and contributes significantly to the computed cosmic
inspiral rate of compact binary systems.


title: Baryon Dynamics, Dark Matter Substructure, and Galaxies

abstract:
  By comparing a collisionless cosmological N-body simulation (DM) to an SPH
simulation with the same initial conditions, we investigate the correspondence
between the dark matter subhalos produced by collisionless dynamics and the
galaxies produced by dissipative gas dynamics in a dark matter background. When
galaxies in the SPH simulation become satellites in larger groups, they retain
local dark matter concentrations (SPH subhalos) whose mass is typically five
times their baryonic mass. The more massive subhalos of the SPH simulation have
corresponding subhalos of similar mass and position in the DM simulation; at
lower masses, there is fairly good correspondence, but some DM subhalos are in
different spatial positions and some suffer tidal stripping or disruption. The
halo occupation statistics of DM subhalos -- the mean number of subhalos,
pairs, and triples as a function of host halo mass -- are very similar to those
of SPH subhalos and SPH galaxies. Gravity of the dissipative baryon component
amplifies the density contrast of subhalos in the SPH simulation, making them
more resistant to tidal disruption. Relative to SPH galaxies and SPH subhalos,
the DM subhalo population is depleted in the densest regions of the most
massive halos. The good agreement of halo occupation statistics between the DM
subhalo and SPH galaxy populations leads to good agreement of their two-point
correlation functions and higher order moments on large scales. The depletion
of DM subhalos in dense regions depresses their clustering at R<1 Mpc/h. In
these simulations, the "conversation" between dark matter and baryons is mostly
one-way, with dark matter dynamics telling galaxies where to form and how to
cluster, but the "back talk" of the baryons influences small scale clustering
by enhancing the survival of substructure in the densest environments.


title: NICMOS Status

abstract:
  We provide an overview of the most important calibration aspects of the
NICMOS instrument on board of HST. We describe the performance of the
instrument after the installation of the NICMOS Cooling System, and show that
the behavior of the instrument has become very stable and predictable. We
detail the improvements made to the NICMOS pipeline and outline plans for
future developments. The derivation of the absolute photometric zero-point
calibration is described in detail. Finally, we describe and quantify a newly
discovered count-rate dependent non-linearity in the NICMOS cameras. This new
non-linearity is distinctly different from the total count dependent
non-linearity that is well known for near-infrared detectors. We show that the
non-linearity has a power law behavior, with pixels with high system, or vice
versa, pixels with low count rate detecting slightly less than expected. The
effect has a wavelength dependence with observations at the shortest
wavelengths being the most affected (~0.05-0.1 mag per dex flux change at ~1
micron, 0.03 mag per dex at 1.6 micron).


title:
Mass Distribution of Spiral Galaxies in a Thin Disk Model with Velocity
  Curve Extrapolation

abstract:
  We model a spiral galaxy by a thin axially symmetric disk that includes both
visible and dark matter. The surface mass density of the disk is calculated
directly from the rotational velocity curve without extra assumptions. We
simplify the standard application of the model. Since most velocity curves are
known out to some radius, r_{max}, we extrapolate them by attaching a Keplerian
tail. The numerical procedure and the extrapolation are tested with a known toy
mass density and shown to reconstruct it with a good precision if r_{max}
includes a sufficient part of the velocity curve. Mass density curves are
calculated for Milky Way and NGC 3198. We vary the extent of the flat part of
the velocity curves from 30 kpc to 200 kpc and show that does not affect
appreciably the calculated mass density inside r_{max}=30 kpc. The
reconstructed masses for Milky Way are 15 x 10^10 solar masses inside the
visible disk and 23 x 10^10 solar masses inside 30 kpc. For NGC 3198, the
reconstructed mass inside the visible disk is 6.5 x 10^10 solar masses and 11 x
10^10 solar masses inside 30 kpc. The total galactic masses are roughly
proportional to the extent of the flat part of the velocity curves which is
currently unknown. The high light-to-mass ratios obtained for the visible disks
of the galaxies - 11 solar units for Milky way and 9.3 for NGC 3198 - suggest
presence of dark matter. The method is also applied to NGC 3031 - a spiral
galaxy with a declining velocity curve in which case it is able to reconstruct
both the mass density curve and the total mass (14 x 10^10 solar masses).


title: Optical spectroscopy of the dwarf nova U Geminorum

abstract:
  U Gem is unique in having a direct measurement of K1 = 107 +- 2 km/s, Long et
al. 1999). We present high-resolution optical spectra of the dwarf nova U Gem
in quiescence taken to test the accuracy to which the HST value can be
recovered from optical data. We find that, even with data of very high S/N we
cannot recover Long et al.'s value to better than about 20% by any method.
Contamination by neighbouring emission lines seems a likely culprit. Our data
reveal a number of new features: Doppler tomograms show emission at low
velocity, close to the centre of mass, and a transient, narrow absorption
feature is seen in the Balmer lines near the line centres at the time of
eclipse. We suggest that stellar prominences, as previously invoked for the
dwarf novae IP Peg and SS Cyg in outburst, may explain both of these features.
The He II 4686.75 A line emission is dominated by the gas stream/disc impact
region. Two distinct spots are seen in Doppler maps, the first being very
narrow and showing a velocity close to that of the accretion disc in the impact
region, and the second much broader and located between the velocities of the
(ballistic) stream and the (Keplerian) disc. We present tentative evidence of
weak spiral structure. We find no evidence of stream-disc overflow in the
system. Our data suggests an inclination angle > 70 degrees, adding to the
evidence of a puzzle in the mass of U Gem's white dwarf. The mass donor is
clearly seen in the Doppler maps, with emission concentrated towards its poles,
and mainly on the side facing the white dwarf. This suggests irradiation with
shielding by the disc from which we estimate an H/R ratio between 0.15 and
0.25.


title: Compton Spectrum from Poynting Flux Accelerated e+e- Plasma

abstract:
  We report the Compton scattering emission from the Poynting flux acceleration
of electron- positron plasma simulated by the 2-1/2 dimensional
particle-in-cell(PIC) code. We show these and other remarkable properties of
Poynting flux acceleration and Compton spectral output, and discuss the
agreement with the observed spectra of GRBs and XRFs.


title: Particle Acceleration by Electromagnetic-Dominated Outflows

abstract:
  We review recent developments in particle acceleration by Poynting flux using
plasma kinetic simulations, and discuss their potential applications to
gamma-ray burst phenomenology


title:
The Ages of Elliptical Galaxies from Infrared Spectral Energy
  Distributions

abstract:
  The mean ages of early-type galaxies obtained from the analysis of optical
spectra, give a mean age of 8 Gyr at z = 0, with 40% being younger than 6 Gyr.
Independent age determinations are possible by using infrared spectra (5-21
microns), which we have obtained with the Infrared Spectrograph on the Spitzer
Observatory. This age indicator is based on the collective mass loss rate of
stars, where mass loss from AGB stars produces a silicate emission feature at
9-12 microns. This feature decreases more rapidly than the shorter wavelength
continuum as a stellar population ages, providing an age indicator. From
observations of 30 nearby early-type galaxies, 29 show a spectral energy
distribution dominated by stars and one has significant emission from the ISM
and is excluded. The infrared age indicators for the 29 galaxies show them all
to be old, with a mean age of about 10 Gyr and a standard deviation of only a
few Gyr. This is consistent with the ages inferred from the values of M/L_B,
but is inconsistent with the ages derived from the optical line indices, which
can be much younger. All of these age indicators are luminosity-weighted and
should be correlated, even if multiple-age components are considered. The
inconsistency indicates that there is a significant problem with either the
infrared and the M/L_B ages, which agree, or with the ages inferred from the
optical absorption lines.


title:
Variability of the NGC 1333 IRAS 4A Outflow: Molecular Hydrogen and
  Silicon Monoxide Images

abstract:
  The NGC 1333 region was observed in the H2 1-0 S(1) line. The H2 images cover
a 5' x 7' region around IRAS 4. Numerous H2 emission features were detected.
The northeast-southwest bipolar outflow driven by IRAS 4A was studied by
combining the H2 images with SiO maps published previously. The SiO-H2 outflows
are continuous on the southwestern side but show a gap on the northeastern
side. The southwestern outflow lobe curves smoothly, and the position angle
increases with the distance from the driving source. The base and the outer tip
of the northeastern outflow lobe are located at positions opposite to the
corresponding parts of the southwestern lobe. This point-symmetry suggests that
the outflow axis may be drifting or precessing clockwise in the plane of the
sky and that the cause of the axis drift may be intrinsic to the outflow
engine. The axis drift model is supported by the asymmetric lateral intensity
profile of the SiO outflow. The axis drift rate is about 0.011 deg yr-1. The
middle part of the northeastern outflow does not exactly follow the point
symmetry because of the superposition of two different kinds of directional
variability: the axis drift of the driving source and the deflection by a dense
core. The axis drift model provides a good explanation for the large deflection
angle of the northeastern outflow. Other H2 emission features around the IRAS 4
region are discussed briefly. Some of them are newly found outflows, and some
are associated with outflows already known before.


title: Talk about Pivots

abstract:
  We consider two different methods of parameterizing the dark energy equation
of state in order to assess possible ``figures of merit'' for evaluating dark
energy experiments. The two models are $w(a) = w_0 + (1-a)w_a$ and $w(a) = w_p
+ (a_p - a)w_a$. This brief note shows that the size of the error contours
cannot change under such a reparameterization. This makes the figures of merit
associated with these parameterizations mathematically identical. This also
means that any ``bias'' exhibited by one model is equally present in the other.


title: The Great Attractor and the Shapley Concentration

abstract:
  We develop a non-linear relativistic model of the Shapley Concentration (SC)
and its environs, including the Great Attractor (GA) and the Local Group (LG).
We take the Shapley concentration as a major attractive centre, and we use the
Lemaitre-Tolman model. We constrain our model with present day observations,
plus the requirement that it have a physically reasonable evolution from small
perturbations at last scattering. We investigate possible mass and velocity
distributions, and we find that the peculiar velocity maximum near the SC is
\~800 km/s inwards, the density between GA and SC must be about ~0.9 times
background, the mass of the GA is probably 4 - 6 x 10^15 M_sun, the SC's
contribution to the LG motion is negligible, and the value of the cosmological
constant is not significant on this scale.


title: Primordial gas cooling behind shock waves in merging halos

abstract:
  We investigate thermal regime of the baryons behind shock waves arising in
the process of virialization of dark matter halos. We find a fraction of the
shocked gas cooled by radiation of HD molecules down to the temperature of the
cosmic microwave background (CMB): this fraction increases sharply from about
$f_{\rm c}\sim 10^{-3}$ for dark halos of $M=5\times 10^7\msun$ to $\sim 0.1$
for halos with $M=10^8\msun$ at $z=10$. We show, however, that further increase
of the mass does not lead to a significant growth of $f_{\rm c}$ -- the
assymptotic value for $M\gg 10^8\msun$ is of 0.2. We estimate star formation
rate associated with such shock waves, and show that it can be a small but not
negligible fraction of the star formation connected with cooling by HI and
H$_2$. We argue that extremely metal-poor low-mass stars in the Milky Way may
have been formed from primordial gas behind such shocks.


title: High frequency observations of southern pulsars

abstract:
  We present polarization data for 32 mainly southern pulsars at 8.4 GHz. The
observations show that the polarization fraction is low in most pulsars at this
frequency except for the young, energetic pulsars which continue to show
polarization fractions in excess of 60 per cent. All the pulsars in the sample
show evidence for conal emission with only one third also showing core
emission. Many profiles are asymmetric, with either the leading or the trailing
part of cone not detectable. Somewhat surprisingly, the asymmetric profiles
tend to be more polarized than the symmetrical profiles. Little or no pulse
narrowing is seen between 1 and 8.4 GHz. The spectral behaviour of the
orthogonal polarization modes and radius to frequency mapping can likely
account for much of the observational phenomenology. Highly polarized
components may orginate from higher in the magnetosphere than unpolarized
components.


title:
The stellar masses of 25000 galaxies at 0.2<z<1.0 estimated by the
  COMBO-17 survey

abstract:
  We present an analysis of stellar mass estimates for a sample of 25000
galaxies from the COMBO-17 survey over the interval 0.2<z<1.0. We have
developed, implemented, and tested a new method of estimating stellar
mass-to-light ratios, which relies on redshift and spectral energy distribution
(SED) classification from 5 broadband and 12 medium band filters. We find that
the majority (>60%) of massive galaxies with M_* > 10^{11} solar masses at all
z<1 are non-star-forming; blue star-forming galaxies dominate at lower masses.
We have used these mass estimates to explore the evolution of the stellar mass
function since z=1. We find that the total stellar mass density of the universe
has roughly doubled since z~1. Our measurements are consistent with other
measurements of the growth of stellar mass with cosmic time and with estimates
of the time evolution of the cosmic star formation rate. Intriguingly, the
integrated stellar mass of blue galaxies with young stars has not significantly
changed since z~1, even though these galaxies host the majority of the star
formation: instead, the growth of the total stellar mass density is dominated
by the growth of the total mass in the largely passive galaxies on the red
sequence.


title:
Chandra Observations of Nuclear Outflows in the Elliptical Galaxy
  NGC4552 in the Virgo Cluster

abstract:
  We use a 54.4 ks Chandra observation to study nuclear outflow activity in
NGC4552 (M89), an elliptical galaxy in the Virgo Cluster. Chandra images in the
0.5-2 keV band show two ring-like features ~1.7 kpc in diameter in the core of
NGC4552, as reported previously by Filho et al. We use spherically symmetric
point explosion shock models to argue that the shape of the surface brightness
profile across the rims of the rings and the temperature of hot gas in the
rings are consistent with a Mach 1.7 shock carrying mean mechanical power
L_shock ~ 3 x 10^{41} ergs/s produced by a ~1.4 x 10^{55} ergs nuclear outburst
\~1 - 2 Myr ago. We find the gas temperature in the central ~100 pc of the
galaxy to be 1.0 +/- 0.2 keV, hotter than elsewhere in the galaxy, suggesting
that we may be observing directly the reheating of the galaxy ISM by the
outburst.


title: Eight billion years of disk galaxy evolution: no galaxy is an island

abstract:
  We present a brief discussion of the evolution of disk galaxy stellar masses,
sizes, rotation velocities, and star formation rates over the last eight
billion years. Recent observations have failed to detect significant evolution
in the stellar mass Tully-Fisher relation, stellar mass-size relation, and the
stellar mass function of disk galaxies. Yet, most z<1 star formation is in
disks, and this star formation would be expected to drive a rapid growth of the
total stellar mass (and therefore mass function) of disks in the last eight
billion years. Such a build-up is not seen; instead, a rapid build-up in the
total stellar mass in non-star-forming spheroid-dominated galaxies is observed.
Large numbers of disk-dominated galaxies are systematically shutting off their
star formation and building up a spheroid (or losing a disk) in the epoch
0<z<1.


title:
An Extended FUSE Survey of Diffuse O VI Emission in the Interstellar
  Medium

abstract:
  We present a survey of diffuse O VI emission in the interstellar medium
obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). Spanning 5.5
years of FUSE observations, from launch through 2004 December, our data set
consists of 2925 exposures along 183 sight lines, including all of those with
previously-published O VI detections. The data were processed using an
implementation of CalFUSE v3.1 modified to optimize the signal-to-noise ratio
and velocity scale of spectra from an aperture-filling source. Of our 183 sight
lines, 73 show O VI 1032 emission, 29 at > 3-sigma significance. Six of the
3-sigma features have velocities |v_LSR| > 120 km/s, while the others have
|v_LSR| < 50 km/s. Measured intensities range from 1800 to 9100 LU, with a
median of 3300 LU. Combining our results with published O VI absorption data,
we find that an O VI-bearing interface in the local ISM yields an electron
density n_e = 0.2--0.3 cm^-3^ and a path length of 0.1 pc, while O VI-emitting
regions associated with high-velocity clouds in the Galactic halo have
densities an order of magnitude lower and path lengths two orders of magnitude
longer. Though the O VI intensities along these sight lines are similar, the
emission is produced by gas with very different properties.


title:
Confronting quintessence models with recent high-redshift supernovae
  data

abstract:
  We confront the predictions of different quintessence models with recent
measurements of the luminosity distance from two sets of supernovae type Ia. In
particular, we consider the 157 SNe Ia in the Gold dataset with z<1.7, and the
more recent data containing 71 supernovae obtained by the Supernova Legacy
Survey (SNLS) with z<1. We numerically solve the evolution equations for the
Ratra-Peebles inverse power law model, the double exponential and the
hyperbolic cosine quintessence models. We obtain confidence regions from the
two datasets in the \Omega_M-\alpha and \Omega_M-w_\phi planes for the
different models and compare their predictions with dark energy models with
constant equation of state.


title: Occam's razor meets WMAP

abstract:
  Using a variety of quantitative implementations of Occam's razor we examine
the low quadrupole, the ``axis of evil'' effect and other detections recently
made appealing to the excellent WMAP data. We find that some razors {\it fully}
demolish the much lauded claims for departures from scale-invariance. They all
reduce to pathetic levels the evidence for a low quadrupole (or any other low
$\ell$ cut-off), both in the first and third year WMAP releases. The ``axis of
evil'' effect is the only anomaly examined here that survives the humiliations
of Occam's razor, and even then in the category of ``strong'' rather than
``decisive'' evidence. Statistical considerations aside, differences between
the various renditions of the datasets remain worrying.


title: Precision Measurement of Optical Pulsation using a Cherenkov Telescope

abstract:
  During 2003, a camera designed to measure the optical pulsations of pulsars
was installed on a telescope of the H.E.S.S. array. The array is designed for
gamma-ray astronomy in the ~100 GeV - 100 TeV energy regime. The aims of this
exercise were two-fold: to prove the pulsar timing capabilities of H.E.S.S. on
all relevant time-scales, and to explore the possibility of performing
sensitive optical pulsar measurements using the ~100 m^2 mirror of a Cherenkov
telescope. Measurements of the Crab pulsar with this instrument demonstrate an
order of magnitude sensitivity improvement over previous attempts using
Cherenkov telescopes. Here we describe the design and performance of the system
and discuss design considerations for future instruments of this type.


title: The Carbon-Rich Gas in the Beta Pictoris Circumstellar Disk

abstract:
  The edge-on disk surrounding the nearby young star Beta Pictoris is the
archetype of the "debris disks", which are composed of dust and gas produced by
collisions and evaporation of planetesimals, analogues of Solar System comets
and asteroids. These disks provide a window on the formation and early
evolution of terrestrial planets. Previous observations of Beta Pic concluded
that the disk gas has roughly solar abundances of elements [1], but this poses
a problem because such gas should be rapidly blown away from the star, contrary
to observations of a stable gas disk in Keplerian rotation [1, 2]. Here we
report the detection of singly and doubly ionized carbon (CII, CIII) and
neutral atomic oxygen (OI) gas in the Beta Pic disk; measurement of these
abundant volatile species permits a much more complete gas inventory. Carbon is
extremely overabundant relative to every other measured element. This appears
to solve the problem of the stable gas disk, since the carbon overabundance
should keep the gas disk in Keplerian rotation [3]. New questions arise,
however, since the overabundance may indicate the gas is produced from material
more carbon-rich than the expected Solar System analogues.


title:
The potential for tidally heated icy and temperate moons around
  exoplanets

abstract:
  Moons of giant planets may represent an alternative to the classical picture
of habitable worlds. They may exist within the circumstellar habitable zone of
a parent star, and through tidal energy dissipation they may also offer
alternative habitable zones, where stellar insolation plays a secondary, or
complementary, role. We investigate the potential extent of stable satellite
orbits around a set of 74 known extrasolar giant planets located beyond 0.6 AU
from their parent stars - where moons should be long-lived with respect to
removal by stellar tides. Approximately 60% of these giant planets can sustain
satellites or moons in bands up to $\sim 0.04$ AU in width. For comparison, the
Galiean satellites extend to $\sim 0.013$ AU. We investigate the stellar
insolation that moons would experience for these exoplanet systems, and the
implications for sublimation loss of volatiles. We find that between 15 and 27%
of {\em all} known exoplanets may be capable of harboring small, icy, moons. In
addition, some 22-28% of all known exoplanets could harbor moons within a
``sublimation zone'', with insolation temperatures between 273 K and 170 K. A
simplified energy balance model is applied to the situation of temperate moons,
maintained by a combination of stellar insolation and tidal heat flow. We
demonstrate that large moons ($>0.1 $M$_{\oplus}$), at orbital radii
commensurate with those of the Galilean satellites, could maintain temperate,
or habitable, surface conditions during episodes of tidal heat dissipation of
the order 1-100 times that currently seen on Io. (Abridged).


title: Substructure in lensing clusters and simulations

abstract:
  We present high-resolution mass reconstructions for five massive
cluster-lenses spanning a redshift range from $z = 0.18$--0.57 utilising
archival {\it Hubble Space Telescope} ({\it HST}) data and applying
galaxy-galaxy lensing techniques. These detailed mass models were obtained from
the observations by combining constraints from the strong and weak lensing
regimes. We ascribe local weak distortions in the shear maps to perturbations
induced by the presence of galaxy haloes around individual bright early-type
cluster member galaxies. This technique constrains the mass enclosed within an
aperture for these subhaloes. We are sensitive to a specific mass range for
these subhaloes, $10^{11}$ -- $10^{12.5} \msun$, which we associate with
galaxy-scale subhaloes. Adopting a parametric model for the subhaloes, we also
derive their velocity dispersion function and the aperture radius function. The
mass spectrum of substructure in the inner regions of the observed clusters is
directly compared with that in simulated clusters extracted from the {\it
Millennium Simulation}. The massfunction, aperture radii and velocity
dispersion function are compared in detail. Overall, we find good agreement
between the distribution of substructure properties retrieved using the lensing
analysis and those obtained from the simulation (truncated abstract).