title: The Clustering of Extragalactic Extremely Red Objects

abstract:
  We have measured the angular and spatial clustering of 671 K<18.40, R-K>5
Extremely Red Objects (EROs) from a 0.98 square degree sub-region of the NOAO
Deep Wide-Field Survey (NDWFS). Our study covers nearly 5 times the area and
has twice the sample size of any previous ERO clustering study. The wide field
of view and BwRIK passbands of the NDWFS allow us to place improved constraints
on the clustering of z=1 EROs. We find the angular clustering of EROs is
slightly weaker than in previous measurements, and w(1')=0.25+/-0.05 for
K<18.40 EROs. We find no significant correlation of ERO spatial clustering with
redshift, apparent color or absolute magnitude, although given the
uncertainties, such correlations remain plausible. We find the spatial
clustering of K<18.40, R-K>5 EROs is well approximated by a power-law, with
r_0=9.7+/-1.1 Mpc/h in comoving coordinates. This is comparable to the
clustering of 4L* early-type galaxies at z<1, and is consistent with the
brightest EROs being the progenitors of the most massive ellipticals. There is
evidence of the angular clustering of EROs decreasing with increasing apparent
magnitude, when NDWFS measurements of ERO clustering are combined with those
from the literature. Unless the redshift distribution of K>20 EROs is very
broad, the spatial clustering of EROs decreases from r_0=9.7+/-1.1 Mpc/h for
K<18.40 to r_0=7.5 Mpc/h for K>20 EROs.


title:
Near-Infrared Properties of Faint X-rays Sources from NICMOS Imaging in
  the Chandra Deep Fields

abstract:
  We measure the near-infrared properties of 42 X-ray detected sources from the
Chandra Deep Fields North and South, the majority of which lie within the
NICMOS Hubble Deep Field North and Ultra Deep Field. We detect all 42 Chandra
sources with NICMOS, with 95% brighter than H = 24.5. We find that X-ray
sources are most often in the brightest and most massive galaxies. Neither the
X-ray fluxes nor hardness ratios of the sample show any correlation with
near-infrared flux, color or morphology. This lack of correlation indicates
there is little connection between the two emission mechanisms and is
consistent with the near-infrared emission being dominated by starlight rather
than a Seyfert non-stellar continuum.
  Near-infrared X-ray sources make up roughly half of all extremely red (J-H >
1.4) objects brighter than H > 24.5. These red X-ray sources have a range of
hardness ratios similar to the rest of the sample, decreasing the likelihood of
dust-obscured AGN activity as the sole explanation for their red color. Using a
combination of spectroscopic and photometric redshifts, we find the red J-H
objects are at high redshifts (z > 1.5), which we propose as the primary
explanation for their extreme J-H color. Measurement of rest-wavelength
absolute B magnitudes shows that X-ray sources are the brightest optical
objects at all redshifts, which explains their dominance of the bright end of
the red J-H population.


title:
Possible evolutionary transition from rapidly rotating neutron stars to
  strange stars due to spin-down

abstract:
  We present a scenario of formation of strange stars due to spin-down of {\it
rapidly rotating} neutron stars left after supernova explosions . By assuming a
process where the total baryon mass is conserved but the angular momentum is
lost due to emission of gravitational waves and/or the magnetic braking, we
find that the transition from rapidly rotating neutron stars to slowly rotating
strange stars is possible; a large amount of energy $\sim 10^{53} ergs $ could
be released. The liberated energy might become a new energy source for a
delayed explosion of supernova. Furthermore, our scenario suggests that the
supernova associated with gamma-ray bursts could become candidates for targets
in the future observation of gravitational waves.


title:
The early stage of a cosmic collision? XMM-Newton unveils two obscured
  AGN in the galaxy pair ESO509-IG066

abstract:
  We report the XMM-Newton discovery of a X-ray bright AGN pair in the
interacting galaxy system ESO509-IG066. Both galaxies host an X-ray luminous
(L_X ~10^{43} erg/s) obscured nucleus with column densities N_H~7x10^{22} and
N_H~5x10^{21} atoms/cm/cm. The optical morphology is only mildly disturbed,
suggesting a merging system in the early stage of its evolution. Still, the
pair is probably gravitationally bound, and might eventually evolve into a
compact, fully gas embedded systems such as NGC6240.


title:
Nearby Large-Scale Structures and the Zone of Avoidance: A Conference
  Summary and Assessment

abstract:
  This conference has brought together many of the world's `cosmographers',
particularly those focussed on the mapping nearby large-scale structures. Not
surprisingly, numerous portrayals of the Local Cosmic Web and its
characteristics have been presented, with some reconciliation to the structures
found by the much deeper 2dF Galaxy Redshift Survey and the Sloan Digital Sky
Survey. In recent years, Near-infrared and H I surveys have greatly narrowed
the `Zone of Avoidance' caused by the foreground obscuration of the Milky Way.
There has been emphasis towards southern large-scale structures, with the
particular need to identify the mass overdensities responsible for the dipole
in the Cosmic Microwave Background. While the general consensus is that the
Shapley Concentration is a greater overdensity than the Great Attractor, its
far greater distance makes it unclear as to whether its gravitational effect
could be larger. Furthermore, worries about residual bulk motion remain.


title:
Percolation Properties of Nearby Large-Scale Structures: Every Galaxy
  has a Neighbour

abstract:
  The distribution of nearby (cz < 7500 km/s) galaxies has been explored by
minimal spanning trees; allowance has been made for the drastic decrease of
data with distance. The investigation finds that all galaxies are members of
irregular elongated large-scale structures; there are no `field galaxies'.
Based on our local large-scale structure, every galaxy appears to have a
neighbouring galaxy within <100 km/s (1.4 h_{70}^{-1} Mpc) of redshift space,
and thereby all galaxies are found to lie in filaments or tree configurations.
  Every large-scale structure appears to have a neighbouring large-scale
structure within <700 km/s (10 h_{70}^{-1} Mpc), such that large-scale
structures interconnect to form a continuous labyrinth.


title: The Collinder 69 cluster in the context of the Lambda Orionis SFR

abstract:
  The Lambda Orionis Star Forming Region is a complex structure which includes
the Col 69 (Lambda Orionis) cluster and the B30 & B35 dark clouds. We have
collected deep optical photometry and spectroscopy in the central cluster of
the SFR (Col 69), and combined with 2MASS IR data, in order to derive the
Initial Mass Function of the cluster, in the range 50-0.02 M(sun). In addition,
we have studied the H(alpha) and lithium equivalent widths, and the
optical-infrared photometry, to derive an age (5+-2 Myr) for Col 69, and to
compare these properties to those of B30 & B35 members.


title: A Prototype for Science Alerts

abstract:
  Many of the science goals of the GAIA mission, especially for bursting or
time-varying phenomena like supernovae or microlensing, require an early
identification, analysis and release of preliminary data. The alerting on rare
and unusual events is the scientific equivalent of the finding of needles in
haystacks or the panning for gold-dust in rivers. In modern signal processing,
such novelty detection is routinely performed with self-organising maps (SOMs),
which are an unsupervised clustering algorithm invented by Kohonen. Here, we
describe the application of SOMS to the classification of data provided by
large-scale surveys such as GAIA and to the despatching of scientific alerts.
We illustrate our ideas by processing the publically available OGLE II dataset
towards the Bulge, identifying major classes of variable stars (such as novae,
small amplitude red giant variables, eclipsing binaries and so on) and
extracting the rare, discrepant lightcurves from which the alerts can be drawn.


title: Mapping WR140 from infrared spectroscopy and imaging

abstract:
  Observations of the 1.083-micron He I line in WR140 (HD 193793) show P-Cygni
profiles which varied as the binary system went through periastron passage. A
sub-peak appeared on the normally flat-topped emission component and then moved
across the profile consistent with its formation in the wind-collision region.
Variation of the absorption component provided constraints on the opening angle
(theta) of the wind-collision region. Infrared (2-10 micron) images observed
with a variety of instruments in 2001-04 resolve the dust cloud formed in 2001,
and show it to be expanding at a constant rate. Owing to the high eccentricity
of the binary orbit, the dust is spread around the orbital plane in a 'splash'
and we compare the dust images with the orientation of the orbit.


title: 26Al and 60Fe from massive stars

abstract:
  We discuss the production of 26Al and 60Fe in two massive star models, namely
a 25 and a 80 Msun, of initial solar metallicity.


title: Probing Galactic reddening with the 8620 A diffuse interstellar band

abstract:
  Using the correlation between the equivalent width of the diffuse
interstellar band (DIB) at 8620 A and the interstellar reddening reported by
Munari (2000) GAIA could directly trace the interstellar extinction throughout
the Galaxy. We checked for the magnitude and distance limitations of this
method in 42 Galactic directions by simulating the RVS data on the stellar
sample provided by the model of stellar population synthesis of the Galaxy
(Robin et al. 2003). The simulation indicates that the imprint of the 8620 A
DIB will be detected in the RVS spectra of stars with magnitudes up to V~16
with sufficient accuracy to trace not only the distribution of the interstellar
medium but also the radial component of its kinematic motion, i.e. the radial
velocity of the mass center of the dust cloud in the line of sight.


title:
The role of environment in triggering starburst galaxies: A sample of
  isolated galaxies

abstract:
  The project AMIGA (Analysis of the interstellar Medium of Isolated GAlaxies)
will provide a statistically significant sample of the most isolated galaxies
in the northern sky. Such a control sample is necessary to assess the role of
the environment in galaxy properties and evolution. The sample is based on the
Catalogue of Isolated Galaxies (CIG, Karachentseva, 1973) and the database will
include blue and near-infrared luminosities, far-infrared (FIR) emission,
atomic gas (HI) emission, radio continuum, and, for a redshift limited
subsample of about 200 galaxies, CO and H$\alpha$ emission. The data will be
released and periodically updated at http://www.iaa.csic.es/AMIGA.html. Here,
we present the project and its status, as well as a preliminary analysis of the
relation between star formation activity and the environment. We found a trend
that the galaxies with asymmetric HI spectrum also tend to show an enhanced
star formation, traced by a high value of $L_{FIR}/M(HI)$, indicating that a
perturbed gas kinematics and enhanced SF are related.


title:
A Survey for Low-Mass Stars and Brown Dwarfs in the Eta Cha and Eps Cha
  Young Associations

abstract:
  I present the results of a search for new low-mass stars and brown dwarfs in
the Eta Cha and Eps Cha young associations. Within radii of 1.5 and 0.5 deg
surrounding Eta Cha and Eps Cha, respectively, I have constructed
color-magnitude diagrams from DENIS and 2MASS photometry and have obtained
spectra of the candidate low-mass members therein. The five candidates in Eta
Cha are classified as four field M dwarfs and one carbon star. No new members
are found in this survey, which is complete for M_sun=0.015-0.15 according to
the evolutionary models of Chabrier and Baraffe. Thus, an extended population
of low-mass members is not present in Eta Cha out to four times the radius of
the known membership. Meanwhile, the three candidate members of Eps Cha are
classified as young stars, and thus likely members of the association, based on
Li absorption and gravity-sensitive absorption lines. These new sources have
spectral types of M2.25, M3.75, and M5.75, corresponding to masses of 0.45,
0.25, and 0.09 M_sun by the models of Chabrier and Baraffe. For one of these
stars, intense H(alpha) emission, forbidden line emission, and strong K-band
excess emission suggest the presence of accretion, an outflow, and a disk,
respectively. This young star is also much fainter than expected for an
association member at its spectral type, which could indicate that it is seen
in scattered light. No brown dwarfs are detected in Eps Cha down to the
completeness limit of 0.015 M_sun. The absence of brown dwarfs in these
associations is statistically consistent with the mass functions measured in
star-forming regions, which exhibit only ~2 and ~1 brown dwarfs for stellar
samples at the sizes of the Eta Cha and Eps Cha associations.


title:
Spectroscopic Confirmation of the Least Massive Known Brown Dwarf in
  Chamaeleon

abstract:
  We present spectroscopy of two candidate substellar members of the Chamaeleon
I star-forming region. The candidates, which were identified photometrically by
Oasa, Tamura, & Sugitani, have been observed at 1-2.5 micron during
commissioning of the Gemini Near-Infrared Spectrograph. The late-type nature of
one of the candidates, OTS 44, is confirmed through the detection of strong
steam absorption bands. The other object, OTS 7, exhibits no late-type features
and is likely a background star or galaxy. The gravity-sensitive shape of the
H- and K-band continua demonstrate that OTS 44 is a young, pre-main-sequence
object rather than a field dwarf. We measure a spectral type of M9.5 for OTS 44
based on a comparison of its spectrum to data for optically-classified young
late-type objects. Because OTS 44 is the coolest and faintest object with
confirmed membership in Chamaeleon I, it is very likely the least massive known
member of the cluster. By comparing the position of OTS 44 on the H-R diagram
to the evolutionary models of Chabrier & Baraffe, we infer a mass of ~0.015
M_sun. Although this estimate is uncertain by at least a factor of two, OTS 44
is nevertheless one of the least massive free-floating brown dwarfs confirmed
spectroscopically to date.


title: Detections of Molecular Hydrogen in the Outer Filaments of NGC 1275

abstract:
  We present clear spectroscopic detections of molecular hydrogen in the outer
filaments of the H-alpha nebula surrounding the central galaxy of the Perseus
cluster, NGC 1275. This implies the presence of warm molecular gas clouds at
projected distances up to 24 kpc from the nucleus of the host galaxy, embedded
in the hot intracluster medium. The emission-line intensity ratios reveal that
the molecular hydrogen is predominately thermally excited with excitation
temperatures of 1600-2200K, suggesting a lack of pressure balance between the
molecular component and its surrounding medium. Excitation by stellar UV or by
the central AGN is shown to be unlikely, whilst thermal excitation by X-rays or
conduction from the ICM or shocks are all possibilities. Evidence for a
non-thermal component is found in the spectra of some regions based on a low
ortho-to-para ratio.


title: New Brown Dwarfs and an Updated Initial Mass Function in Taurus

abstract:
  I have performed a search for young low-mass stars and brown dwarfs (BDs) in
2 regions encompassing a total area of 4 deg^2 in the Taurus star-forming
region, discovering 15 new members of Taurus. In addition, I present 7 new
members outside of these areas from the initial stage of a survey of all of
Taurus. These 22 objects exhibit spectral types of M4.5-M9.25 and masses of
0.3-0.015 M_sun according to the theoretical evolutionary models of Baraffe and
Chabrier, 7 of which are likely to be BDs. Emission in H(alpha), He I, Ca II,
[O I], and [S II] and excess emission in optical and near-IR bands among some
of these objects suggest the presence of accretion, outflows, and circumstellar
disks. The results from the 4 deg^2 survey have been combined with previous
studies of Taurus to arrive at an IMF for a total area of 12.4 deg^2. As in the
previous IMFs for Taurus, the updated IMF peaks at a higher mass (0.8 M_sun)
than the mass functions in IC 348 and Orion (0.1-0.2 M_sun). Meanwhile, the
deficit of BDs in Taurus appears to be less significant (x1.4-1.8) than found
in earlier studies (x2) because of a slightly higher BD fraction in the new IMF
for Taurus and a lower BD fraction in the new spectroscopic IMF for the
Trapezium from Slesnick and coworkers. The spatial distribution of the low-mass
stars and BDs discovered in the two new survey areas closely matches that of
the more massive members. Thus, on the degree size scales (~3 pc) probed to
date, there is no indication that BDs form through ejection.


title:
The Initial Mass Function toward the low-mass end in the Large
  Magellanic Cloud with HST/WFPC2 Observations

abstract:
  We present V and I equivalent HST/WFPC2 photometry of two areas in the Large
Magellanic Cloud: The southern part of the stellar association LH 52, located
on the western edge of the super-shell LMC 4, and a field between two
associations, which is located on the southwestern edge of the shell, and which
accounts for the general background field of the galaxy. The HST/WFPC2
observations reach magnitudes as faint as V=25 mag, much deeper than have been
observed earlier in stellar associations in the LMC. We determine the MF for
main-sequence stars in the areas. Its slope (Gamma) in both areas is steeper
for stars with masses M < 2 M_solar (-4 < Gamma < -6), compared with stars of M
> 2 M_solar (-1 < Gamma < -2). Thus, as far as the field of the LMC concerns
the MF does not have a uniform slope throughout its observed mass range. The MF
of the general field of the LMC was found previously to be steeper than the MF
of a stellar association for massive stars with M > 5 M_solar. We conclude that
this seems to be also the case toward lower masses down to M ~ 1 M_solar. Our
data allow to construct the field-subtracted, incompleteness-corrected,
main-sequence MF of the southwestern part of the young stellar association LH
52, which accounts for the Initial Mass Function (IMF) of the system. Its mean
slope is found to be comparable, but still more shallow than a typical Salpeter
IMF (Gamma = -1.12 +/- 0.24) for masses down to ~ 1 M_solar. We found
indications that the IMF of the association probably is ``top-heavy'', due to
the large number of intermediate-mass stars in the field of the system, while
the general LMC field is found to be responsible for the low-mass population,
with M < 2 M_solar, observed in both fields.


title:
FLAMINGOS Spectroscopy of New Low-Mass Members of the Young Cluster IC
  348

abstract:
  We present spectroscopy of candidate stellar and substellar members of the
young cluster IC 348. Using the Florida Multi-Object Imaging Near-Infrared
Grism Observational Spectrometer with the 4 meter telescope at Kitt Peak
National Observatory, we have obtained multi-object moderate-resolution
(R=1000) J- and H-band spectra of 66 infrared sources (H=12-17) toward IC 348,
many of which are difficult to observe spectroscopically at optical wavelengths
(I>20) because they are highly reddened and/or intrinsically cool and red. We
have also observed 19 known cluster members that have optical spectral types
available from previous work. By using these latter sources as the spectral
classification standards, we have identified 14 new members of the cluster with
types of M2-M6 in the sample of 66 new objects. Two additional objects exhibit
types of >M8.5, but cannot be conclusively classified as either field dwarfs or
cluster members with available data. We have estimated extinctions,
luminosities, and effective temperatures for these 16 M-type objects, placed
them on the H-R diagram, and used the evolutionary models of Chabrier & Baraffe
to estimate their masses. If the two candidates at >M8.5 are indeed members,
they should be among the least massive known brown dwarfs in IC 348
(M/M_sun~0.01).


title: The supernova rate per unit mass

abstract:
  We compute the rate of supernovae (SNe) of different types along the Hubble
sequence normalized to the near-infrared luminosity and to the stellar mass of
the parent galaxies. This is made possible by the new complete catalog of
near-infrared galaxy magnitudes obtained by 2MASS. We find that the rates of
all SN types, including Ia, Ib/c and II, show a sharp dependence on both the
morphology and the (B-K) colors of the parent galaxies and, therefore, on the
star formation activity. In particular we find, with a high statistical
significance, that the type Ia rate in late type galaxies is a factor ~20
higher than in E/S0. Similarly, the type Ia rate in the galaxies bluer than
B-K=2.6 is about a factor of 30 larger than in galaxies with B--K>4.1. These
findings can be explained by assuming that a significant fraction of Ia events
in late Spirals/Irregulars originates in a relatively young stellar component.


title:
Extragalactic Source Counts in the Spitzer 24-micron Band: What Do We
  Expect From ISOCAM 15-micron Data and Models?

abstract:
  The comparison between the new Spitzer data at 24 micron and the previous
ISOCAM data at 15 micron is a key tool to understand galaxy properties and
evolution in the infrared and to interpret the observed number counts, since
the combination of Spitzer with the ISO cosmological surveys provides for the
first time the direct view of the Universe in the Infrared up to z~2. We
present the prediction in the Spitzer 24-micron band of a phenomenological
model for galaxy evolution derived from the 15-micron data. Without any ``a
posteriori'' update, the model predictions seem to agree well with the recently
published 24-micron extragalactic source counts, suggesting that the peak in
the 24-micron counts is dominated by ``starburst'' galaxies like those detected
by ISOCAM at 15 micron, but at higher redshifts (1 < z < 2 instead of 0.5 < z <
1.5).


title:
Decomposition of the visible and dark matter in the Einstein ring
  0047-2808 by semi-linear inversion

abstract:
  We measure the mass density profile of the lens galaxy in the Einstein ring
system 0047-2808 using our semi-linear inversion method developed in an earlier
paper. By introducing an adaptively gridded source plane, we are able to
eliminate the need for regularisation of the inversion. This removes the
problem of a poorly defined number of degrees of freedom, encountered by
inversion methods that employ regularisation, and so allows a proper
statistical comparison between models. We confirm the results of Wayth et al.
(2004), that the source is double, and that a power-law model gives a
significantly better fit that the singular isothermal ellipsoid model. We
measure a slope alpha=2.11+/-0.04. We find, further, that a dual-component
constant M/L baryonic + dark halo model gives a significantly better fit than
the power-law model, at the 99.7% confidence level. The inner logarithmic slope
of the dark halo profile is found to be 0.87^{+0.69}_{-0.61} (95% CL),
consistent with the predictions of CDM simulations of structure formation. We
determine an unevolved B-band mass to light ratio for the baryons (only) of
3.05^{+0.53}_{-0.90} h_65 M_sol/L_Bsol (95% CL). This is the first measurement
of the baryonic M/L of a single galaxy by purely gravitational lens methods.
The baryons account for 65^{+10}_{-18}% (95% CL) of the total projected mass,
or, assuming spherical symmetry, 84^{+12}_{-24}% (95% CL) of the total
three-dimensional mass within the mean radius of 1.16'' (7.5 h_65^{-1} kpc)
traced by the ring. Finally, at the level of >3sigma, we find that the halo
mass is rounder than the baryonic distribution and that the two components are
offset in orientation from one another.


title: The Parkes HI Survey of the Magellanic System

abstract:
  We present the first fully and uniformly sampled, spatially complete HI
survey of the entire Magellanic System with high velocity resolution, performed
with the Parkes Telescope. The final data-cubes have an rms noise of sigma ~
0.05 K and an effective angular resolution of 16 arcmin. The Large Magellanic
Cloud (LMC) and the Small Magellanic Cloud (SMC) are associated with huge
gaseous features with a total HI mass of M(HI) = 4.87 10^8 M_sun [d/55 kpc]^2,
if all HI gas is at the same distance of 55 kpc. Approximately two thirds of
this HI gas is located close to the Magellanic Clouds (Magellanic Bridge and
Interface Region), and 25% of the HI gas is associated with the Magellanic
Stream. The Leading Arm has a four times lower HI mass than the Magellanic
Stream, corresponding to 6% of the total HI mass of the gaseous features. We
have analyzed the velocity field of the Magellanic Clouds and their
neighborhood introducing a LMC-standard-of-rest frame. The HI in the Magellanic
Bridge shows low velocities relative to the Magellanic Clouds suggesting an
almost parallel motion, while the gas in the Interface Region has significantly
higher relative velocities indicating that this gas is leaving the Magellanic
Bridge building up a new section of the Magellanic Stream. The clouds in the
Magellanic Stream and the Leading Arm show significant differences, both in the
column density distribution and in the shapes of the line profiles. The HI gas
in the Magellanic Stream is more smoothly distributed than the gas in the
Leading Arm. These morphological differences can be explained if the Leading
Arm is at considerably lower z-heights and embedded in a higher pressure
ambient medium.


title: Hypernovae and light dark matter as possible Galactic positron sources

abstract:
  The electron-positron annihilation source in the Galactic center region has
recently been observed with INTEGRAL/SPI, which shows that this 511 keV source
is strong and its extension is consistent with the Galactic bulge geometry. The
positron production rate, estimated to more than 10$^{43}$ per second, is very
high and raises a challenging question about the nature of the Galactic
positron source. Commonly considered astrophysical positron injectors, namely
type Ia supernovae are rare events and fall short to explain the observed
positron production rate. In this paper, we study the possibility of Galactic
positron production by hypernovae events, exemplified by the recently observed
SN2003dh/GRB030329, an asymmetric explosion of a Wolf-Rayet star associated
with a gamma-ray burst. In these kinds of events, the ejected material becomes
quickly transparent to positrons, which spread out in the interstellar medium.
Non radioactive processes, such as decays of heavy dark matter particles
(neutralinos) predicted by most extensions of the standard model of particle
physics, could also produce positrons as byproducts. However they are expected
to be accompanied by a large flux of high-energy gamma-rays, which were not
observed by EGRET and ground based Tcherenkov experiments. In this context we
explore the possibility of direct positron production by annihilation of light
dark matter particles.


title:
A numerical fit of analytical to simulated density profiles in dark
  matter haloes

abstract:
  Analytical and geometrical properties of generalized power-law (GPL) density
profiles are investigated in detail. In particular, a one-to-one correspondence
is found between mathematical parameters and geometrical parameters. Then GPL
density profiles are compared with simulated dark haloes (SDH) density
profiles, and nonlinear least-absolute values and least-squares fits involving
the above mentioned five parameters (RFSM5 method) are prescribed. More
specifically, the sum of absolute values or squares of absolute logarithmic
residuals is evaluated on a large number of points making a 5-dimension
hypergrid, through a few iterations. The size is progressively reduced around a
fiducial minimum, and superpositions on nodes of earlier hypergrids are
avoided. An application is made to a sample of 17 SDHs on the scale of cluster
of galaxies, within a flat $\Lambda$CDM cosmological model (Rasia et al. 2004).
In dealing with the mean SDH density profile, a virial radius, averaged over
the whole sample, is assigned, which allows the calculation of the remaining
parameters. Using a RFSM5 method provides a better fit with respect to other
methods. No evident correlation is found between SDH dynamical state (relaxed
or merging) and asymptotic inner slope of the logarithmic density profile or
(for SDH comparable virial masses) scaled radius. Mean values and standard
deviations of some parameters are calculated, and a comparison with previous
results is made with regard to the scaled radius. A certain degree of
degeneracy is found in fitting GPL to SDH density profiles. If it is intrinsic
to the RFSM5 method or it could be reduced by the next generation of
high-resolution simulations, still remains an open question.


title: "Pi of the Sky" - all-sky, real-time search for fast optical transients

abstract:
  An apparatus to search for optical flashes in the sky is described. It has
been optimized for gamma ray bursts (GRB) optical counterparts. It consists of
2x16 cameras covering all the sky. The sky is monitored continuously and the
data are analysed on-line. It has self-triggering capability and can react to
external triggers with negative delay. The prototype with two cameras has been
installed at Las Campanas (Chile) and is operational from July 2004. The paper
presents general idea and describes the apparatus in detail. Performance of the
prototype is briefly reviewed and perspectives for the future are outlined.


title: NGC 7468: a galaxy with an inner polar disk

abstract:
  We present our spectroscopic observations of the galaxy NGC 7468 performed at
the 6-m Special Astrophysical Observatory telescope using the UAGS long-slit
spectrograph, the multipupil fiber spectrograph MPFS, and the scanning
Fabry-Perot interferometer (IFP). We found no significant deviations from the
circular rotation of the galactic disk in the velocity field in the regions of
brightness excess along the major axis of the galaxy (the putative polar ring).
Thus, these features are either tidal structures or weakly developed spiral
arms. However, we detected a gaseous disk at the center of the galaxy whose
rotation plane is almost perpendicular to the plane of the galactic disk. The
central collision of NGC 7468 with a gas-rich dwarf galaxy and their subsequent
merging seem to be responsible for the formation of this disk.


title:
Far Ultraviolet observations of the High Mass X-ray Binary
  4U1700-37/HD153919

abstract:
  The high-mass X-ray binary 4U1700-37/HD153919 has been observed with FUSE to
study the effect of the X-ray source on the stellar wind of the primary. Phase
dependent changes in the wind lines have been observed, indicating the creation
of a X-ray ionization zone in the stellar wind. The X-ray luminosity of
4U1700-37 ionizes much of the wind and leaves a Stromgren zone. This disrupts
the resonance-line acceleration of the wind in portions of the orbit, quenching
the wind and disrupting the mass flow. This effect was found for the first time
in 4U1700-37. This so-called Hatchett-McCray (HM) effect had been predicted for
4U1700-37, but was not previously detected.


title: Radio-optical scrutiny of the central engine in compact AGN

abstract:
  We combine Very-Long-Baseline Interferometry (VLBI) data for $\sim100$ active
galactic nuclei (AGN) available from the Very Large Baseline Array (VLBA) 2 cm
imaging survey and optical spectroscopy to investigate the relationships in the
emission-line region--central engine--radio jet system. Here, we present the
diversity of spectral types among the brightest AGN in our sample. We also
discuss correlations between the mass of the central engine and properties of
the parsec-scale radio jet for 24 AGN selected by the presence of H$\beta$
broad-emission lines in their spectra.


title:
Abundances in the H I envelope of the extremely low-metallicity Blue
  Compact Dwarf Galaxy SBS 0335-052 from Far Ultraviolet Spectroscopic Explorer
  observations

abstract:
  We present FUSE spectroscopy of SBS 0335-052, the second most metal-deficient
blue compact dwarf (BCD) galaxy known (log O/H = -4.70). In addition to the H I
Lyman series, we detect C II, N I, N II, O I, Si II, Ar I and Fe II absorption
lines, mainly arising from the extended H I envelope in which SBS 0335-052 is
embedded. No H2 absorption lines are seen. The absence of diffuse H2 implies
that the warm H2 detected through infrared emission must be very clumpy and
associated with the star-forming regions.The clumps should be denser than ~
1000 cm^-3 and hotter than ~ 1000 K and account for > 5% of the total H I mass.
Although SBS 0335-052 is a probable young galaxy, its neutral gas is not
pristine. The metallicity of its neutral gas is similar to that of its ionized
gas and is equal log O/H ~ -5. This metallicity is comparable to those found in
the H I envelopes of four other BCDs with ionized gas metallicities spanning
the wide range from log O/H = -4.8 to log O/H = -3.8, and in Ly-alpha
absorbers, fueling the speculation that there may have been previous enrichment
of the primordial neutral gas to a common metallicity level of log O/H ~ -5,
possibly by Population III stars.


title: NGC 6231: X-ray properties of the early-type star population

abstract:
  Based on a deep XMM-Newton observation of the young open cluster NGC 6231, we
derive the main X-ray properties of its early-type star population. Among the
610 X-ray sources detected in the field, 42 are associated with early-type
stars. We investigate their $L_\mathrm{X} / L_\mathrm{bol}$ relationship and we
confirm the clear dichotomy between O- and B-type stars. The cut-off line
between the two behaviours occurs at $L_\mathrm{bol} \sim 10^{38}$ erg s$^{-1}$
as previously proposed by \citet{BSC97}. The distinction between single and
binary stars is not clear cut, except for the colliding wind system HD 152248.
The X-ray detected B-stars in NGC 6231 appear to be more luminous than
predicted from the \citeauthor{BSC97} relation. Though this suggests a bimodal
distribution of the B-star X-ray emission, we caution however that these
results might be biased by detection limits. Finally we investigate the X-ray
variability of the detected sources and we find that about 40% of the X-ray
emitters in the field of view present consistent signs of variability in the
EPIC instruments. This fraction is much larger than previously thought. About
one third of the early-type stars population, either singles or binaries,
further shows variability. These variations do not seem to be exclusively
related to binarity and could thus not be systematically interpreted in the
framework of a wind-wind collision phenomenon.


title:
A hydrodynamic model for asymmetric explosions of rapidly rotating
  collapsing supernovae with a toroidal atmosphere

abstract:
  We numerically solved the two-dimensional axisymmetric hydrodynamic problem
of the explosion of a low-mass neutron star in a circular orbit. In the initial
conditions, we assumed a nonuniform density distribution in the space
surrounding the collapsed iron core in the form of a stationary toroidal
atmosphere that was previously predicted analytically and computed numerically.
The conﬁguration of the exploded neutron star itself was modeled by a
torus with a circular cross section whose central line almost coincided with
its circular orbit. Using an equation of state for the stellar matter and the
toroidal atmosphere in which the nuclear statistical equilibrium conditions
were satisfied, we performed a series of numerical calculations that showed the
propagation of a strong divergent shock wave with a total energy of 0.2x10^51
erg at initial explosion energy release of 1.0x10^51 erg. In our calculations,
we rigorously took into account the gravitational interaction, including the
attraction from a higher-mass (1.9M_solar) neutron star located at the
coordinate origin, in accordance with the rotational explosion mechanism for
collapsing supernovae.W e compared in detail our results with previous similar
results of asymmetric supernova explosion simulations and concluded that we
found a lower limit for the total explosion energy.


title:
On the conservation of second-order cosmological perturbations in a
  scalar field dominated universe

abstract:
  We discuss second-order cosmological perturbations on super-Hubble scales, in
a scalar field dominated universe, such as during single field inflation. In
this contest we show that the gauge-invariant curvature perturbations defined
on uniform density and comoving hypersurfaces coincide and that perturbations
are adiabatic in the large scale limit. Since it has been recently shown that
the uniform density curvature perturbation is conserved on large scales if
perturbations are adiabatic, we conclude that both the uniform density and
comoving curvature perturbations at second-order, in a scalar field dominated
universe, are conserved. Finally, in the light of this result, we comment on
the variables recently used in the literature to compute non-Gaussianities.


title:
Lens Galaxy Environments and Anomalous Flux Ratios in Gravitational
  Lenses

abstract:
  The fraction of substructures required to account for anomalous flux ratios
in gravitational lens systems appears to be higher than that predicted in the
standard cold dark matter cosmology. We present a possible alternative route to
anomalous flux ratios from lens galaxy environments. We consider the compound
lens system such that a lens galaxy lie in a group or cluster, and estimate the
contribution of substructures in the group/cluster to the fraction using an
analytic model of substructures. We find that the contribution becomes dominant
when the impact parameter of the lens is less than ~30% of the virial radius of
the group/cluster. This indicates that the environmental effect can partly
explain the high incidence of anomalous flux ratios.


title: A multi-wavelength study of the starburst galaxy NGC 7673

abstract:
  HST/WFPC2 images resolved NGC 7673 into a large number of star clusters.
Among these, 31 fall inside the IUE large aperture, which was used to acquire
an integrated ultraviolet spectrum of the galaxy. We have fitted Starburst99
evolutionary synthesis models to the observed colours of these clusters and
derived ages, reddenings, and masses of the clusters. Then a simple sum of the
clusters synthetic UV spectra has been compared to the observed IUE spectrum,
in order to investigate the star formation history of NGC 7673.


title:
Systematically Asymmetric Heliospheric Magnetic Field: Evidence for a
  Quadrupole Mode and Non-axisymmetry with Polarity Flip-flops

abstract:
  Recent studies of the heliospheric magnetic field (HMF) have detected
interesting, systematic hemispherical and longitudinal asymmetries which have a
profound significance for the understanding of solar magnetic fields. The in
situ HMF measurements since 1960s show that the heliospheric current sheet
(HCS) is systematically shifted (coned) southward during solar minimum times,
leading to the concept of a bashful ballerina. While temporary shifts can be
considerably larger, the average HCS shift (coning) angle is a few degrees,
less than the $7.2^{\circ}$ tilt of the solar rotation axis. Recent solar
observations during the last two solar cycles verify these results and show
that the magnetic areas in the northern solar hemisphere are larger and their
intensity weaker than in the south during long intervals in the late declining
to minimum phase. The multipole expansion reveals a strong quadrupole term
which is oppositely directed to the dipole term. These results imply that the
Sun has a symmetric quadrupole S0 dynamo mode that oscillates in phase with the
dominant dipole A0 mode. Moreover, the heliospheric magnetic field has a strong
tendency to produce solar tilts that are roughly opposite in longitudinal
phase. This implies is a systematic longitudinal asymmetry and leads to a
"flip-flop" type behaviour in the dominant HMF sector whose period is about 3.2
years. This agrees very well with the similar flip-flop period found recently
in sunspots, as well as with the observed ratio of three between the activity
cycle period and the flip-flop period of sun-like stars. Accordingly, these
results require that the solar dynamo includes three modes, A0, S0 and a
non-axisymmetric mode. Obviously, these results have a great impact on solar
modelling.


title:
Did Open Solar Magnetic Field Increase during the Last 100 Years: A
  Reanalysis of Geomagnetic Activity

abstract:
  Long-term geomagnetic activity presented by the aa index has been used to
show that the heliospheric magnetic field has more than doubled during the last
100 years. However, serious concern has been raised on the long-term
consistency of the aa index and on the centennial rise of the solar magnetic
field. Here we reanalyze geomagnetic activity during the last 100 years by
calculating the recently suggested IHV (Inter-Hour Variability) index as a
measure of local geomagnetic activity for seven stations. We find that local
geomagnetic activity at all stations follows the same qualitative long-term
pattern: an increase from early 1900s to 1960, a dramatic dropout in 1960s and
a (mostly weaker) increase thereafter. Moreover, at all stations, the activity
at the end of the 20th century has a higher average level than at the beginning
of the century. This agrees with the result based on the aa index that global
geomagnetic activity, and thereby, the open solar magnetic field has indeed
increased during the last 100 years. However, quantitatively, the estimated
centennial increase varies greatly from one station to another. We find that
the relative increase is higher at the high-latitude stations and lower at the
low and mid-latitude stations. These differences may indicate that the fraction
of solar wind disturbances leading to only moderate geomagnetic activity has
increased during the studied time interval. We also show that the IHV index
needs to be corrected for the long-term change of the daily curve, and
calculate the corrected IHV values. Most dramatically, we find the centennial
increase in global geomagnetic activity was considerably smaller, only about
one half of that depicted by the aa index.


title:
Isocurvature constraints on gravitationally produced superheavy dark
  matter

abstract:
  We show that the isocurvature perturbations imply that the gravitationally
produced superheavy dark matter must have masses larger than few times the
Hubble expansion rate at the end of inflation. This together with the bound on
tensor to scalar contribution to the CMB induces a lower bound on the reheating
temperature for superheavy dark matter to be about 10^7 GeV. Hence, if the
superheavy dark matter scenario is embedded in supergravity models with gravity
mediated SUSY breaking, the gravitino bound will squeeze this scenario.
Furthermore, the CMB constraint strengthens the statement that gravitationally
produced superheavy dark matter scenario prefers a relatively large tensor mode
amplitude if the reheating temperature must be less than 10^9 GeV.


title: A Probe of the Matter Content of Quasar Jets

abstract:
  We propose a method for estimating the matter content of quasar jets which
exhibit Chandra - detected knots in their kpc scale jets. The method relies on
measuring the component of the Cosmic Microwave Background (CMB) radiation that
is bulk-Comptonized (BC) by the cold electrons in the relativistically flowing
jet. We apply our method to PKS 0637 - 752, a superluminal quasar with an one
-- sided Chandra - detected large scale jet. What makes this source
particularly suited for such a procedure is the absence of significant
non-thermal jet emission in the 'bridge', the region between the core and the
first bright knot, guaranteeing that most of the electrons in the bridge are
cold, and leaving the BC scattered CMB radiation as the only significant source
of photons in this region. At lambda=3.6-8.0 microns, the most likely band for
the BC scattered emission to appear, the angular resolution of Spitzer (~ 1''-
3'') is considerably smaller than the bridge of PKS 0637 -- 752 (~8''), making
it possible to both measure and resolve this emission.


title: Constraining the Equation of State with Moment of Inertia Measurements

abstract:
  We estimate that the moment of inertia of star A in the recently discovered
double pulsar system PSR J0737-3039 may be determined after a few years of
observation to something like 10% accuracy. This would enable accurate
estimates of the radius of the star and the presure of matter in the vicinity
of 1 to 2 times the nuclear saturation density, which would in turn provide
strong constraints on the equation of state of neutron stars and the physics of
their interiors.


title:
Neutrinos from the Galactic Center in the Light of its Gamma-Ray
  Detection at TeV Energy

abstract:
  We re-evaluate the event rate expected in km^3-scale detectors for neutrinos
from the direction of the Galactic Center (GC) in light of recent spectral
measurements obtained by the HESS instrument for ~TeV gamma-radiation from this
direction. In the most plausible scenario the re-evaluated event rate is
smaller than that previously calculated--and here re-calculated--on the basis
of EGRET data. However, the GC TeV gamma-ray detections by the Whipple,
CANGAROO, and HESS instruments, together with the strong indications for an
overabundance of cosmic rays coming from the GC at EeV energies, strengthen the
expectation for a detectable, TeV-PeV GC neutrino signal from proton-proton
interactions in that region. If the TeV gamma-ray--EeV cosmic ray anisotropy
connection is correct, this signal will be detectable within a year and half
for km^3-scale neutrino detectors in the Northern Hemisphere at super-TeV
energies and, significantly, should also be detectable in 1.6 years by the
South Polar IceCube detector at energies > 10^14 eV. The GC neutrino signal
should also produce a detectable signal from neutrino showering and resonant
W^- production by anti-electron-neutrinos in the volume of a km^3-scale
detector.


title:
Optical and near-infrared properties of submillimetre galaxies in the
  GOODS-North field

abstract:
  We investigate the photometric redshift distribution, colours and
morphologies of a large sample of submillimetre sources in the GOODS-North
region. With the depth achieved by the deep ACS images, optical counterparts
have been found for all the radio-detected sub-mm sources, and we have used
several techniques to identify counterparts to the radio-undetected sources.
The sub-mm counterparts have a median photometric redshift, from optical and
near-IR photometry, of 1.9. Our sample contains a much higher fraction of EROs
than other sub-mm surveys, and larger angular sizes than the average galaxy at
all redshifts. The sub-mm galaxy counterparts are consistent with massive
star-forming galaxies at high redshift.


title:
A universal density slope - velocity anisotropy relation for relaxed
  structures

abstract:
  We identify a universal relation between the radial density slope \alpha (r)
and the velocity anisotropy \beta (r) for equilibrated structures. This
relation holds for a variety of systems, including disk galaxy mergers,
spherical collapses, cold dark matter (CDM) halos both with and without
cooling. We argue that the shape of the relation is reasonable from fundamental
principles when the dark matter or stars are assumed to obey Tsallis
statistics, and in that case we fit the \alpha - \beta relation with just one
free parameter. One can use this result to close the Jeans equations, for
example to construct mass models of elliptical galaxies from observational data
or to tune dark matter direct detection experiments. We also predict the
asymptotic central slope and anisotropy of CDM halos to be approximately -1 and
0.


title: The Stellar IMF as a Property of Turbulence

abstract:
  We propose to interpret the stellar IMF as a property of the turbulence in
the star--forming gas. Gravitationally unstable density enhancements in the
turbulent flow collapse and form stars. Their mass distribution can be derived
analytically from the power spectrum of the turbulent flow and the isothermal
shock jump conditions in the magnetized gas. For a power spectrum index
\beta=1.74, consistent with Larson's velocity dispersion--size relation as well
as with new numerical and analytic results on supersonic turbulence, we obtain
a power law mass distribution of dense cores with a slope equal to
3/(4-\beta)=1.33, consistent with the slope of Salpeter's stellar IMF. Below
one solar mass, the mass distribution flattens and turns around at a fraction
of a solar mass, as observed for the stellar IMF in a number of stellar
clusters, because only the densest cores are gravitationally unstable. The mass
distribution at low masses is determined by the Log--Normal distribution of the
gas density. The intermittent nature of this distribution is responsible for
the generation of a significant number of collapsing cores of brown dwarf mass.


title:
Structure formation with strongly interacting neutrinos - implications
  for the cosmological neutrino mass bound

abstract:
  We investigate a model where neutrinos are strongly coupled to a new, light
scalar field. In this model neutrinos annihilate as soon as they become
non-relativistic in the early universe, and a non-zero neutrino mass has a
marginal effect on the matter power spectrum. However, the angular power
spectrum of the cosmic microwave background (CMB) is changed significantly
because the strongly interacting fluid of neutrinos and scalars does not
experience any anisotropic stress. Such models are strongly disfavoured by
current observations. Interestingly, this leads to the conclusion that the
relativistic energy density around the epoch of recombination must be in the
form of very weakly interacting particles. This conclusion is independent of
the specific interaction model.


title:
Cosmological particle-based simulations of galaxy formation; numerical
  loss of angular momentum and disk heating

abstract:
  We discuss the role that numerical effects have in cosmological N-Body/SPH
simulations of disk galaxy formation. We show that the resolution of current
state-of-the-art calculations, about $10^5$ SPH and dark matter particles
within the virial radius of a Milky Way-sized halo at $z=0$, is just enough to
avoid artificial losses of angular momentum and dramatic numerical disk heating
during the phase of disk assembly. Instead both effects will still be an issue
at earlier epochs, when the progenitors of the final galaxies are resolved by
significantly less than $10^5$ particles.This must be at least partially
responsible for why simulations show a ubiquitous low angular momentum spheroid
that is too massive compared to that of typical disk galaxies


title:
Site Evaluation and RFI spectrum measurements in Portugal at the
  frequency range 0.408-10 GHz for a GEM polarized galactic radio emission
  experiment

abstract:
  We probed for Radio Frequency Interference (RFI) for the three potential
Galactic Emission Mapping Experiment (GEM) sites at Portugal using custom made
omnidirectional disconic antennas. For the installation of a 10-meter dish
dedicated to the mapping of Polarized Galactic Emission foreground planned for
2005-2007 in the 5-10 GHz band, the three sites chosen as suitable to host the
antenna were surveyed for local radio pollution in the frequency range
[0.01-10] GHz. Tests were done to look for radio broadcasting and mobile phone
emission lines in the radio spectrum. The results show one of the sites to be
almost entirely RFI clean and showing good conditions to host the experiment.


title:
Gravitational-Wave Signature of an Inspiral into a Supermassive
  Horizonless Object

abstract:
  Event horizons are among the most intriguing of general relativity's
predictions. Although on firm theoretical footing, direct indications of their
existence have yet to be observed. With this motivation in mind, we explore
here the possibility of finding a signature for event horizons in the
gravitational waves (GWs) produced during the inspiral of stellar-mass compact
objects (COs) into the supermassive ($\sim 10^6 M_\odot$) objects that lie at
the center of most galaxies. Such inspirals will be a major source for LISA,
the future space-based GW observatory. We contrast supermassive black holes
with models in which the central object is a supermassive boson star (SMBS).
Provided the COs interact only gravitationally with the SMBS, stable orbits
exist not just outside the Schwarzschild radius but also inside the surface of
the SMBS as well. The absence of an event horizon allows GWs from these orbits
to be observed. Here we solve for the metric in the interior of a fairly
generic class of SMBS and evolve the trajectory of an inspiraling CO from the
Schwarzschild exterior through the plunge into the exotic SMBS interior. We
calculate the approximate waveforms for GWs emitted during this inspiral.
Geodesics within the SMBS surface will exhibit extreme pericenter precession
and other features making the emitted GWs readily distinguishable from those
emitted during an inspiral into a black hole.


title: Gould's Belt to Starburst Galaxies: The IMF of Extreme Star Formation

abstract:
  Recent results indicate the stellar initial mass function is not a strong
function of star-forming environment or ``initial conditions'' (e.g. Meyer et
al. 2000). Some studies suggest that a universal IMF may extend to sub-stellar
masses (see however Briceno et al. 2002). Yet most of this work is confined to
star-forming environments within 1 kpc of the Sun. In order to probe the
universality of the IMF over a wider range of parameter space (metalicity,
ambient pressure, magnetic field strength) new techniques are required. We
begin by summarizing our approach to deriving the sub-stellar IMF down to the
opacity-limit for fragmentation using NGC 1333 as an example. Next, we describe
results from simulations using the observed point-spread function of the new
6.5m MMT adaptive optics system and examine the confusion-limited sensitivity
to low mass stars in rich star-forming clusters out to 0.5 Mpc. We also present
preliminary results from observations with this system of the W51 star-forming
complex. Finally, we outline a new technique to estimate the ratio of high to
low mass stars in unresolved stellar populations, such as the massive star
clusters observed in interacting galaxies (e.g. Mengel et al. 2002). While
evidence for variations in the IMF remains inconclusive, new studies are
required to rule them out and determine whether or not the IMF is universal
over the range of parameter space relevant to star-forming galaxies over cosmic
time.


title: Brown Dwarfs from Turbulent Fragmentation

abstract:
  The origin of brown dwarfs (BDs) is an important component of the theory of
star formation, because BDs are approximately as numerous as solar mass stars.
It has been suggested that BDs originate from the gravitational fragmentation
of protostellar disks, a very different mechanism from the formation of
hydrogen burning stars. We propose that BDs are instead formed by the process
of turbulent fragmentation, like more massive stars. In numerical simulations
of turbulence and star formation we find that gravitationally unstable density
peaks of BD mass are commonly formed by the turbulent flow. These density peaks
collapse into BD mass objects with circumstellar disks, like more massive
protostars. We rely on numerical experiments with very large resolution,
achieved with adaptive mesh refinement (AMR). The turbulence simulation
presented here is the first AMR turbulence experiment ever attempted and
achieves an effective resolution of 1024^3 computational zones. The star
formation simulation achieves an effective resolution of (10^6)^3 computational
zones, from a cloud size of 5pc to protostellar disks resolved down to 1AU.


title:
High Resolution Spectroscopy of the high galactic latitude RV Tauri star
  CE Virginis

abstract:
  Analysis of the surface composition of the suspected cool RV Tauri star CE
Vir shows no systematic trend in depletions of elements with respect to
condensation temperature. However, there is a significant depletion of the
elements with respect to the first ionization potential of the element. The
derived Li abundance of log $\epsilon$ (Li) = 1.5$\pm$0.2 indicates production
of Li in the star. Near infrared colours indicate sporadic dust formation close
to the photosphere.


title: Intense Diffuse Far-UV Emission from the Orion Nebula

abstract:
  We present spectra of the diffuse FUV (900 -- 1200 \AA) emission from a
region near the Orion Nebula: the first high resolution spectra of the diffuse
background radiation. These observations were made using serendipitous FUSE
observations and were only possible because of the strength of the diffuse
emission (~3 x 10^5 photons cm-2 s-1 sr-1 A-1) and the sensitivity of the FUSE
instrument. Preliminary modeling suggests that the light is scattered starlight
from the Trapezium stars, primarily Theta Ori 1 C. However, a comparison of the
spectra with nearby stars shows significant differences in the presence and
strength of the absorption lines, particularly in the LyB line where there is
much less interstellar absorption in our diffuse spectrum. We believe that we
are indeed observing scattered light from the Trapezium stars but through a
line of sight with much less matter than the direct line to the stars.


title:
Characteristics of EAS and Primary Particle Mass Composition in the
  Energy Region of $10^{17} - 3 \cdot 10^{19}$ eV by Yakutsk Data

abstract:
  In the work the data of the Yakutsk complex EAS array and their comparison
with calculation in the case of primary nuclei of different chemical elements
are presented. The calculation by QGSJET model have been used interpreting
experimental data.


title: Spectrum of cosmic rays with energy above $10^{17}$ eV

abstract:
  There are some discrepancies in the results on energy spectrum from Yakutsk,
AGASA, and HiRes experiments. In this work differential energy spectrum of
primary cosmic rays based on the Yakutsk EAS Array data is presented. For the
largest events values of $S_{600}$ and axes coordinates have been obtained
using revised lateral distribution function. Simulation of converter's response
at large distances showed no considerable underestimation of particle density.
Complex shape of spectrum in region of $\E > 10^{17}$ eV is confirmed. After
adjustment of parameters and additional exposition at the Yakutsk array there
are three events with energy $\E > 10^{20}$ eV.


title: Obscured AGN in Multiwavelength Surveys

abstract:
  Using a simple unification model for AGN, with a fixed ratio of obscured to
unobscured AGN of 3:1, we explain the X-ray, optical and infrared properties of
the X-ray sources in the GOODS fields. That is, the GOODS data are consistent
with the existence of a large population of obscured AGN out to high redshifts.
About half of these are so obscured that they are missed even by hard X-ray
observations, and are detected only in deep infrared observations. The
previously reported decreasing trend of obscured to total AGN ratio with
increasing X-ray luminosity can be explained entirely as a selection effect.


title: The Star Cluster population of NGC 5253

abstract:
  We present a detailed analysis of the star cluster population in the
starburst galaxy NGC 5253. Our work is based on HST optical and VLT Ks images.
We detect more than 300 clusters, and for all of them we derive the photometry
in the V, I and Ks bands and built a color-color V-I/V-Ks diagram. After
correction for star contamination, we matched 115 sources in all the three
bands V, I and Ks. Comparison of the data points with models shows how most of
the sources are affected by a red excess. The ages of the younger clusters are
obtained from a HST Halpha image which allows to partially remove the
degeneracy between age and extinction and to calculate the screen optical depth
toward the clusters. The V and Ks luminosity functions show a marked turnover
at M(V)=-7.3 and M(K)=-10.2, with a shape roughly similar to the gaussian
distribution of old globular clusters. We convert the luminosity function into
a mass function, and find that the clusters younger than 10 Myr show a power
law distribution with slope -1.6, while the distribution of the older clusters
has a maximum at about 4x10^4 Msun.


title:
Towards the Event Horizon - The Vicinity of AGN at Micro-Arcsecond
  Resolution

abstract:
  We summarize the present status of VLBI experiments at 3 mm (86 GHz), 2 mm
(129-150 GHz) and 1.3 mm (215-230 GHz). We present and discuss a new 3 mm VLBI
map of M87 (Virgo A), which has a spatial resolution of only approx. 20
Schwarzschild radii. We discuss recent VLBI results for SgrA* and argue in
favor of new observations within an extended European mm-VLBI network, in order
to search for variability. We discuss the possibilities to image the `event
horizon' of a super-massive black hole at wavelengths < 2mm, and conclude that
the addition of large and sensitive millimetre telescopes such as CARMA, the
SMA, the LMT and ALMA will be crucial for this.


title: A simple model of the Auroral Kilometric Radiation visibility

abstract:
  Data collected with Polrad swept frequency analyzer during almost 2.5 years
of Interball-2 mission are used to investigate the directivity properties of
AKR observed in the Northern Hemisphere. In contrast with the previous, mostly
statistical studies, single dynamic spectra have been analyzed. Simple modeling
of AKR source visibility from the location of the observer makes possible to
find approximate locations of remotely observed radiation sources and to model
the overall form of the dynamic spectrum with a single set of geometric
parameters valid during up to tens of minutes. Cases of filled and partially
filled emission cones are found as well as smaller emission cones embedded in
the main cone. Anisotropic AKR beams aligned with subcones as thin as 10
degrees and sometimes narrower have been detected.


title: Hierarchical Merging, Ultraluminous and Hyperluminous X-ray Sources

abstract:
  Various arguments strongly suggest that the population of ultraluminous X-ray
sources (ULXs: apparent X-ray luminosity > Eddington limit for 10 Msun ~10^39
erg/s) in nearby galaxies are mostly stellar-mass X-ray binaries in unusual
evolutionary stages. However there are indications that the very brightest
systems may be difficult to explain this way. Accordingly we consider the class
of hyperluminous X-ray sources (HLXs) (i.e. those with apparent bolometric
luminosities >~10^41 erg/s). Because this class is small (currently only the
M82 object is a secure member) we do not need to invoke a new formation
mechanism for its black holes. We explore instead the idea that HLXs may be the
nuclei of satellite galaxies captured during hierarchical merging. The observed
correlation between AGN and tidal interactions implies that HLX activity would
switch on during passage through the host galaxy, close to pericentre. This
suggests that HLXs should appear near the host galaxy, be associated with star
formation, and thus possibly with ULXs.


title:
A family of triaxial modified Hubble mass models: effects of the
  additional radial functions

abstract:
  The projected properties of triaxial generalization of the modified Hubble
mass models are studied. These models are constructed by adding the additional
radial functions, each multiplied by a low-order spherical harmonic, to the
models of \citet{ct00}. The projected surface density of mass models can be
calculated analytically which allows us to derive the analytic expressions of
axial ratio and position angles of major axis of constant density elliptical
contours at asymptotic radii. The models are more general than those studied
earlier in the sense that the inclusions of additional terms in density
distribution, allows one to produce varieties of the radial profile of axial
ratio and position angle, in particular, their small scale variations at inner
radii. Strong correlations are found to exist between the observed axial ratio
evaluated at $0.25 R_{e}$ and at $4 R_{e}$ which occupy well-separated regions
in the parameter space for different choices of the intrinsic axial ratios.
These correlations can be exploited to predict the intrinsic shape of the mass
model, independent of the viewing angles. Using Bayesian statistics, the result
of a test case launched for an estimation of the shape of a model galaxy is
found to be satisfactory.


title: WARP: a WIMP double phase Argon detector

abstract:
  The WARP programme for dark matter search with a double phase argon detector
is presented. In such a detector both excitation and ionization produced by an
impinging particle are evaluated by the contemporary measurement of primary
scintillation and secondary (proportional) light signal, this latter being
produced by extracting and accelerating ionization electrons in the gas phase.
The proposed technique, verified on a 2.3 liters prototype, could be used to
efficiently discriminate nuclear recoils, induced by WIMP's interactions, and
measure their energy spectrum. An overview of the 2.3 liters results and of the
proposed 100 liters detector is shown.


title:
The nature of the Mid-IR faint radio sources from the Spitzer First Look
  Survey

abstract:
  Data from the Spitzer Space Telescope (the First Look Survey - FLS) have
recently been made public. We have compared the 24 micron images with very deep
WSRT 1.4 GHz observations, centred on the FLS verification strip (FLSv).
Approximately 75% of the radio sources have corresponding 24 micron
identifications. Such a close correspondence is expected, especially at the
fainter radio flux density levels, where star forming galaxies are thought to
dominate both the radio and mid-IR source counts. However, a significant
fraction of radio sources detected by WSRT (25%) have no mid-IR detection in
the FLSv (implying a 24 micron flux density less than 0.1 mJy). We present
initial results on the nature of the radio sources without Spitzer
identification, using data from various multi-waveband instruments, including
the publicly available R-band data from the Kitt Peak 4-m telescope.


title: The evolutionary status of the bright high-latitude supergiant HD190390

abstract:
  Despite its mean apparent magnitude of m(v)=6.39, the evolutionary status of
HD190390 (HR7671), a luminous F-type supergiant at high galactic latitude, is
still not very clear, but in most papers a post-AGB classification is assumed.
New observational material has been obtained with four different instruments
and is presented here. An extensive abundance analysis based on high
resolution, high signal-to-noise NTT+EMMI spectra confirms the metal deficiency
of this object ([Fe/H]=-1.6), together with a high lithium content
(log(Li)=1.9). A variability analysis based on Geneva photometry over seven
years reveals beating with a period of +/-3000 days. It is, however, not clear
whether this beating is caused by a stable triplet, or it is the consequence of
small changes in the main frequency. More recent data obtained with the
HIPPARCOS satellite and the Mercator telescope not only confirm the main
period, but also support the presence of a second periodicity of 11 days, which
was also found in the Geneva photometry. A conclusive evolutionary status of
this object is not given, but alternative to the UU Her (i.e. post-AGB) status,
a W Vir classification is discussed.


title:
The effect of using different EOS in modelling the Alpha Centauri binary
  system

abstract:
  In this preliminary study we investigate the effects of using different
equations of state (CEFF and OPAL) in the calibration of the binary system
Alpha Centauri. Constraints coming from the detection of acoustic oscillations
in Alpha Centauri A and B are included in the modelling.


title:
The Minimum Mass for Opacity-Limited Fragmentation in Turbulent Cloud
  Cores

abstract:
  We present a new analysis of the minimum mass for star formation, based on
opacity-limited fragmentation. Our analysis differs from the standard one,
which considers hierarchical fragmentation of a 3-D medium, and yields
$M_{_{\rm MIN}} \sim 0.007 {\rm to} 0.010 M_\odot$ for Population I star
formation. Instead we analyse the more realistic situation in which there is
one-shot fragmentation of a shock-compressed layer, of the sort which arises in
turbulent star-forming clouds. In this situation, $M_{_{\rm MIN}}$ can be
smaller than $0.003 M_\odot$. Our analysis is more stringent than the standard
one in that (a) it requires fragments to have condensation timescales shorter
than all competing mass scales, and (b) it takes into acount that a fragment
grows by accretion whilst it is condensing out, and has to radiate away the
energy dissipated in the associated accretion shock. It also accords with the
recent detection, in young star clusters, of free-floating star-like objects
having masses as low as $0.003 {\rm M}_\odot$.


title: Magnetic helicity and cosmological magnetic field

abstract:
  The magnetic helicity has paramount significance in nonlinear saturation of
galactic dynamo. We argue that the magnetic helicity conservation is violated
at the lepton stage in the evolution of early Universe. As a result, a
cosmological magnetic field which can be a seed for the galactic dynamo obtains
from the beginning a substantial magnetic helicity which has to be taken into
account in the magnetic helicity balance at the later stage of galactic dynamo.


title: Evolution of Thermal Conducting Clouds Embedded in Galactic Winds

abstract:
  We performed high resolution hydrodynamical simulations of dense cool clouds
embedded in supernova-driven galactic superwinds. Here we present preliminary
results of our reference model in which the effect of heat conduction are taken
into account. Significant dynamical differences occur between simulations with
and without heat conduction. In absence of heat conduction the cloud fragments
in few dynamical timescale. The inclusion of heat conduction has the effect to
stabilize the cloud and inhibit the growth of Kelvin-Helmholtz and
Reyleigh-Taylor instabilities. Furthermore in the conditions met in our
simulations the strong heat flux at the cloud edge generates a converging shock
which compresses the cloud. We also calculate the high energy emission (O{\sc
vi} and soft X-ray) of the cloud and O{\sc vi} absorption line properties and
compare the results with obvervations. Models in which heat conduction is taken
into account seem to fit the observations much better. In general only a small
fraction (0.1-0.4%) of the wind mechanical energy intersecting the cloud is
radiated away. Finally some of our models are able to explain the low
metallicity abundance seen in X-ray osservation of superwinds.


title: HI at a Redshift of Zero

abstract:
  While LOFAR and the SKA will enable the study of HI at the epoch of
reionization for the first time, expectations for the distribution of HI at
that redshift depend on our understanding of the cosmological HI mass density
at the present epoch and its variation with environment. We exploit a complete
optical diameter and HI flux limited sample of galaxies in the local universe
to derive a robust measurement of the HIMF for masses log(M / M_{Sun}) > 7.4
which takes into account the effects of local large scale structure.


title: Gas and Stars in an HI-Selected Galaxy Sample

abstract:
  We present the results of a J-band study of the HI-selected Arecibo Dual-Beam
Survey and Arecibo Slice Survey galaxy samples using the 2 Micron All-Sky
Survey data. We find that these galaxies span a wide range of stellar and gas
properties. However, despite the diversity within the samples, we find a very
tight correlation between luminosity and size in the J-band, similar to that we
previously found (Rosenberg & Schneider 2003) between the HI mass and size. We
also find that the correlation between the baryonic mass and the J-band
diameter is even tighter than between the baryonic mass and the rotational
velocity.


title: Star Formation at High Angular Resolution

abstract:
  The role of the SKA in high resolution observations of the formation of low
and high mass stars in the Galaxy is examined. The large collecting area will
have a large impact on dynamical studies at high resolution using spectral
lines. The SKA will allow dramatic progress in the investigation of the
ionised, atomic and molecular phases over a range of evolutionary stages.
Attention is focused here on the potential of radio recombination lines, H I 21
cm line and molecular Zeeman measurements. This combination will unveil the
physical processes that drive jets and winds from young stars. Other important
areas such as pre-biotic molecules, disc ablation in OB clusters and massive
star formation in nearby galaxies are also briefly discussed.


title:
Constraints on Oscillating Quintom from Supernova, Microwave Background
  and Galaxy Clustering

abstract:
  We consider in this paper a simple oscillating Quintom model of dark energy
which has two free parameters and an equation of state oscillating and crossing
-1. For low redshifts the equation of state of this model resembles itself
similar to the linearly parameterized dark energy, however differ substantially
at large redshifts. We fit our model to the observational data separately from
the new high redshift supernova observations from the HST/GOODS program and
previous supernova, CMB and galaxy clustering. Our results show that because of
the oscillating feature of our model the constraints from observations at large
redshifts such as CMB become less stringent.


title: Discovery of hard X-ray features around hotspots of Cygnus A

abstract:
  We present results of analysis of a Chandra observation of Cygnus A in which
the X-ray hotspots at the ends of the jets are mapped in detail. A hardness map
reveals previously unknown structure in the form of outer and inner hard arcs
around the hotspots, with hardness significantly enhanced compared with the
hotspot central regions. The outer hard arcs may constitute the first detection
of the bow shock; the inner hard arcs may reveal where the jets impact on the
hotspots. We argue that these features cannot result from electrons radiating
by the synchrotron self-Compton process. Instead we consider two possible
sources of the hard emission: the outer arcs may be due to thermal radiation of
hot intracluster gas compressed at the bow shock. Alternatively, both outer and
inner arcs may be due to synchrotron radiation of electrons accelerated in
turbulent regions highly perturbed by shocks and shear flows. Comparison of
measured hardness ratios with simulations of the hardness ratios resulting from
these processes show that it is more diffcult to explain the observations with
a thermal model. Although we cannot rule out a thermal model, we argue in
favour of the non-thermal explanation. The hard regions in the secondary
hotspots suggest that jet activity is still powering these hotspots.


title: Dark Matter Direct Detection

abstract:
  Solving the Dark Matter enigma represents one of the key objectives of
contemporary physics. Recent astrophysical and cosmological measurements have
unambiguously demonstrated that ordinary matter contributes to less than 5 % of
the energy budget of our Universe, and that the nature of the remaining 95 % is
unknown. Weakly Interacting Massive Particles (WIMPs) represent the best
motivated candidate to fill the Dark Matter gap, and direct detection Dark
Matter experiments have recently reached sensitivities allowing them to sample
a first part of supersymmetric models compatible with accelerator constraints.
  Three cryogenic experiments currently provide the best sensitivity, by nearly
one order of magnitude, to WIMP interactions. With systematic uncertainties far
less severe than other present techniques, the next generation of cryogenic
experiments promises two orders of magnitude increase in sensitivity over the
next few years. The present results, perspectives and experimental strategies
of the main direct detection experiments are presented. Challenges met by
future ton-scale cryogenic experiments in deep underground sites, aiming at
testing most of the SUSY parameter space, are critically discussed.


title: SN2002kg -- the brightening of LBV V37 in NGC 2403

abstract:
  SN2002kg is a type IIn supernova, detected in October 2002 in the nearby
spiral galaxy NGC 2403. We show that the position of SN2002kg agrees within the
errors with the position of the LBV V37. Ground based and HST ACS images
however show that V37 is still present after the SN2002kg event. We compiled a
lightcurve of V37 which underlines the variablity of the object, and shows that
SN2002kg was the brightening of V37 and not a supernova. The recent brightening
is not a giant eruption, but more likely part of an S Dor phase. V37 shows
strong Halpha +[NII] emission in recent images and in the SN2002kg spectrum,
which we interprete as the signature of the presence of an LBV nebula. A
historic spectrum lacks emission, which may hint that we are witnessing the
formation of an LBV nebula.


title:
Multi-epoch Spectroscopy of IY UMa: Quiescence, Rise, Normal Outburst &
  Superoutburst

abstract:
  We exploit rare observations covering the time before and during a normal
outburst in the deeply-eclipsing SU UMa system IY UMa to study the dramatic
changes in the accretion flow and emission at the onset of outburst. Through
Doppler tomography we study the emission distribution, revealing classic
accretion flow behaviour in quiescence, with the stream-disc impact ionizing
the nearby accretion disc. We observe a delay of hours to a couple of days
between the rise in continuum and the rise in the emission lines at the onset
of the outburst. From line profiles and Doppler maps during normal and
superoutburst we conclude that reprocessing of boundary layer radiation is the
dominant emission line mechanism in outburst, and that the normal outburst
began in the outer disc. The stream-disc impact feature (the `orbital hump') in
the H alpha line flux light curve disappears before the onset of the normal
outburst, and may be an observable signal heralding an impending outburst.


title:
Faint X-ray sources in globular clusters in the XMM-Newton and Chandra
  era

abstract:
  X-ray imaging and spectroscopy can be used to probe the binary content of
globular clusters. Binaries are thought to play a key role in the dynamical
evolution of the clusters by serving as an internal source of energy which
counters the tendency of their cores to collapse. Various kinds of binaries are
found in clusters in X-rays, including BY Dra or RS CVn systems, Cataclysmic
Variables and low mass X-ray binaries as well as millisecond pulsars. In this
review, we will present the most recent X-ray observations of globular clusters
as performed with XMM-Newton and Chandra. We will illustrate the power of X-ray
observations to separate the different X-ray source populations, and emphasize
how the results are important in understanding the binary formation processes.


title: Pulsar dynamics: magnetic dipole model revisited

abstract: Manuscript withdrawn by the authors.


title:
Electromagnetic radiation initiated by hadronic jets from microquasars
  in the ISM

abstract:
  Microquasars are potential candidates to produce a non-negligible fraction of
the observed galactic cosmic rays. The protons accelerated at the jet
termination shock interact with the interstellar medium and may produce
detectable fluxes of extended emission at different energy bands: high-energy
and very high-energy gamma-rays produced by neutral pion-decay, synchrotron and
bremsstrahlung emission in a wide energy range generated by the secondary
electrons produced by charged pion-decay. We discuss the association between
this scenario and some of the unidentified EGRET sources in the galactic plane.


title:
High-energy gamma-ray Emission from Microquasars: LS 5039 and LS I +61
  303

abstract:
  The possible associations between the microquasars LS 5039 and LS I +61 303
and the EGRET sources 3EG J1824-1514 and 3EG J0241+6103 suggest that
microquasars could also be sources of high-energy gamma-rays. In this work, we
present a detailed numerical inverse Compton (IC) model, based on a microquasar
scenario, that reproduces the high-energy gamma-ray spectra and variability
observed by EGRET for the mentioned sources. Our model considers a population
of relativistic electrons entrained in a cylindrical inhomogeneous jet that
interact through IC scattering with both the radiation and the magnetic fields.


title: Planet-sized Detectors for Ultra-high Energy Neutrinos & Cosmic Rays

abstract:
  Extragalactic astronomy with photons ends at ~0.1 PeV, but we know there are
astrophysical sources for seven more decades of energy beyond this. To probe
the highest energy sources and particles in the universe, new messengers, such
as neutrinos, and detectors with planet-sized areas are required. This note
provides a glimpse of the possibilities.


title: Mirages around Kerr black holes and retro-gravitational lenses

abstract:
  Recently Holz & Wheeler (2002) considered a very attracting possibility to
detect retro-MACHOs, i.e. retro-images of the Sun by a Schwarzschild black
hole. In this paper we discuss glories (mirages) formed near rapidly rotating
Kerr black hole horizons and propose a procedure to measure masses and rotation
parameters analyzing these forms of mirages. In some sense that is a
manifestation of gravitational lens effect in the strong gravitational field
near black hole horizon and a generalization of the retro-gravitational lens
phenomenon. We analyze the case of a Kerr black hole rotating at arbitrary
speed for some selected positions of a distant observer with respect to the
equatorial plane of a Kerr black hole. We discuss glories (mirages) formed near
rapidly rotating Kerr black hole horizons and propose a procedure to measure
masses and rotation parameters analyzing these forms of mirages. Some time ago
Falcke et al. (2000) suggested to search shadows at the Galactic Center. In
this paper we present the boundaries for shadows calculated numerically. We
also propose to use future radio interferometer RADIOASTRON facilities to
measure shapes of mirages (glories) and to evaluate the black hole spin as a
function of the position angle of a distant observer.


title: A pair of planets around HD 202206 or a circumbinary planet?

abstract:
  Long-term precise Doppler measurements with the CORALIE spectrograph reveal
the presence of a second planet orbiting the solar-type star HD202206. The
radial-velocity combined fit yields companion masses of m_2\sini = 17.4 M_Jup
and 2.44 M_Jup, semi-major axes of a = 0.83 AU and 2.55 AU, and eccentricities
of e = 0.43 and 0.27, respectively. A dynamical analysis of the system further
shows a 5/1 mean motion resonance between the two planets. This system is of
particular interest since the inner planet is within the brown-dwarf limits
while the outer one is much less massive. Therefore, either the inner planet
formed simultaneously in the protoplanetary disk as a superplanet, or the outer
Jupiter-like planet formed in a circumbinary disk. We believe this singular
planetary system will provide important constraints on planetary formation and
migration scenarios.


title:
A white dwarf-neutron star relativistic binary model for soft gamma-ray
  repeaters

abstract:
  A scenario for SGRs is introduced in which gravitational radiation reaction
effects drive the dynamics of an ultrashort orbital period X-ray binary
embracing a high-mass donor white dwarf (WD) to a rapidly rotating low
magnetised massive neutron star (NS) surrounded by a thick, dense and massive
accretion torus. Driven by GR reaction, sparsely, the binary separation
reduces, the WD overflows its Roche lobe and the mass transfer drives unstable
the accretion disk around the NS. As the binary circular orbital period is a
multiple integer number ($m$) of the period of the WD fundamental mode (Pons et
al. 2002), the WD is since long pulsating at its fundamental mode; and most of
its harmonics, due to the tidal interaction with its NS orbital companion.
Hence, when the powerful irradiation glows onto the WD; from the fireball
ejected as part of the disk matter slumps onto the NS, it is partially
absorbed. This huge energy excites other WD radial ($p$-mode) pulsations
(Podsiadlowski 1991,1995). After each mass-transfer episode the binary
separation (and orbital period) is augmented significantly (Deloye & Bildsten
2003; Al\'ecyan & Morsink 2004) due to the binary's angular momentum
redistribution. Thus a new adiabatic inspiral phase driven by GR reaction
starts which brings the binary close again, and the process repeats. This model
allows to explain most of SGRs observational features: their recurrent
activity, energetics of giant superoutbursts and quiescent stages, and
particularly the intriguing subpulses discovered by BeppoSAX (Feroci et al.
1999), which are suggested here to be {\it overtones} of the WD radial
fundamental mode (see the accompanying paper: Mosquera Cuesta 2004b).


title:
An origin for the main pulsation and overtones of SGR1900+14 during the
  August 27 (1998) superoutburst

abstract:
  The crucial observation on the occurrence of subpulses (overtones) in the
Power Spectral Density of the August 27 (1998) event from SGR1900+14, as
discovered by BeppoSAX (Feroci et al. 1999), has received no consistent
explanation in the context of the competing theories to explain the SGRs
phenomenology: the magnetar and accretion-driven models. Based on the
ultra-relativistic, ultracompact X-ray binary model introduced in the
accompanying paper (Mosquera Cuesta 2004a), I present here a self-consistent
explanation for such an striking feature. I suggest that both the fundamental
mode and the overtones observed in SGR1900+14 stem from pulsations of a massive
white dwarf (WD). The fundamental mode (and likely some of its harmonics) is
excited because of the mutual gravitational interaction with its orbital
companion (a NS, envisioned here as point mass object) whenever the binary
Keplerian orbital frequency is a multiple integer number ($m$) of that mode
frequency (Pons et al. 2002). Besides, a large part of the powerful irradiation
from the fireball-like explosion occurring on the NS (after partial accretion
of disk material) is absorbed in different regions of the star driving the
excitation of other multipoles (Podsiadlowski 1991,1995), i.e., the overtones
(fluid modes of higher frequency). Part of this energy is then reemitted into
space from the WD surface or atmosphere. This way, the WD lightcurve carries
with it the signature of these pulsations inasmuch the way as it happens with
the Sun pulsations in Helioseismology. It is shown that our theoretical
prediction on the pulsation spectrum agrees quite well with the one found by
BeppoSAX (Feroci et al. 1999). A feature confirmed by numerical simulations
(Montgomery & Winget 2000).


title: Abundance of substructure in clusters of galaxies

abstract:
  It is widely recognized that cold dark matter models predict abundant dark
matter substructure in halos of all sizes. Galaxy-galaxy lensing provides a
unique opportunity to directly measure the presence and the mass of such
substructures in clusters of galaxies. Here we present the mass function of
substructures obtained from lensing in massive HST cluster lenses, and compare
it with that obtained from high-resolution cosmological N-body simulations. We
find excellent agreement in the slope and amplitude in the mass range 10^{11} -
10^{12.5} solar masses probed by the observations, highlighting a significant
success of the CDM theory. At lower mass scales, the simulations predict a
large abundance of small substructures below our detection threshold with
galaxy-galaxy lensing, with many of them being plausibly associated with faint
cluster galaxies. Our results suggest that the CDM substructure abundance on
the scale of clusters is in good agreement with present observational data.


title:
The Luminosity Functions of the Galaxy Cluster MS1054-0321 at z=0.83
  based on ACS Photometry

abstract:
  We present new measurements of the galaxy luminosity function (LF) and its
dependence on local galaxy density, color, morphology, and clustocentric radius
for the massive z=0.83 cluster MS1054-0321. Our analyses are based on imaging
performed with the ACS onboard the HST in the F606W, F775W and F850LP passbands
and extensive spectroscopic data obtained with the Keck LRIS. Our main results
are based on a spectroscopically selected sample of 143 cluster members with
morphological classifications derived from the ACS observations. Our three
primary findings are (1) the faint-end slope of the LF is steepest in the
bluest filter, (2) the LF in the inner part of the cluster (or highest density
regions) has a flatter faint-end slope, and (3) the fraction of early-type
galaxies is higher at the bright end of the LF, and gradually decreases toward
fainter magnitudes. These characteristics are consistent with those in local
galaxy clusters, indicating that, at least in massive clusters, the common
characteristics of cluster LFs are established at z=0.83. We also find a 2sigma
deficit of intrinsically faint, red galaxies (i-z>0.5, Mi>-19) in this cluster.
This trend may suggest that faint, red galaxies (which are common in z<0.1 rich
clusters) have not yet been created in this cluster at z=0.83. The
giant-to-dwarf ratio in MS1054-0321 starts to increase inwards of the virial
radius or when Sigma>30 Mpc^-2, coinciding with the environment where the
galaxy star formation rate and the morphology-density relation start to appear.
(abridged)


title:
Do star formation rates of galaxy clusters depend on mass?:
  blue/late-type fractions, total star formation rates of 115 galaxy clusters
  as a function of cluster virial mass

abstract:
  There has been plenty of observational evidence of cluster galaxy evolution
such as the Butcher-Oemler effect and the decrease in S0 fraction with
increasing redshift. As a modern version, the redshift evolution of total star
formation rate (SFR) in clusters has been actively debated recently. However,
these studies of redshift trend have been always hampered by the possible mass
dependence; due to the observational selection effects, clusters found at
higher redshift inevitably tend to be more massive and luminous than local
counterparts. Consequently, one has to correct for the mass trend before
interpreting the redshift trend.
  As an attempt to break this degeneracy, we investigate the mass dependence of
blue/late-type fractions and total SFR of 115 clusters at $z\leq 0.09$ selected
from the Sloan Digital Sky Survey. We find that none of blue/late-type
fractions, total SFR and total SFR normalized by cluster mass shows significant
dependence on cluster virial mass. The scatter is much larger at each cluster
mass than a possible trend. Our results indicates that physical mechanisms that
depend on cluster mass (such as the ram-pressure stripping) are not likely to
be solely responsible for cluster galaxy evolution. Our results also provide an
excellent low redshift comparison sample for future high redshift cluster SFR
studies.


title: Are E+A Galaxies Dusty-Starbursts?: VLA 20cm Radio Continuum Observation

abstract:
  E+A galaxies are characterized as a galaxy with strong Balmer absorption
lines but without any [OII] or Halpha emission lines. Strong Balmer absorption
lines indicate that E+A galaxies have experienced a starburst within the last
<1-1.5 Gyr. However, the lack of emission lines indicates that E+A galaxies do
not have any on-going star formation. Therefore, E+A galaxies are interpreted
as a post-starburst galaxy. However, it has been a mystery why E+A galaxies
underwent a starburst then stopped abruptly.
  One possible explanation to E+A galaxies is the dusty starburst scenario,
where E+A galaxies have on-going star formation, but optical emission lines are
invisible due to the heavy obscuration by dust. To test this dusty starburst
scenario, we have observed 36 E+A galaxies carefully selected from the SDSS DR1
in 20cm radio continuum using the VLA. Since the radio emission is not affected
by the dust extinction, the SFR in dusty galaxies can be revealed by the 20 cm
continuum. All of our 36 target E+A galaxies are selected to have H\delta EW
greater than 6A and no detection of [OII] or Halpha emission lines within 1
sigma. These selection criteria are much stronger than previous E+A selections
in our attempt to select galaxies in the pure post-starburst phase without any
remaining star formation. Except for the two galaxies with a nearby radio
source, none of our 34 E+A galaxies are detected in 20 cm continuum to the
limits reported in Table 1. The obtained upper limits on the radio estimated
SFR suggest that E+A galaxies do not possess strong starburst (> 100 Msun
yr^-1) hidden by dust extinction for the whole sample while 15 (z<0.08) E+As
have lower SFR upper limits of ~15 Msun yr^-1. (Abridged)


title: The Origin of E+A Galaxies

abstract:
  E+A galaxies are galaxies with strong Balmer absorption lines and with no
significant emission in [OII] or H$\alpha$ lines. The existence of strong
Balmer absorption lines shows that these galaxies have experienced a starburst
within the last 1 Gyr. At the same time, these galaxies do not show any sign of
on-going star formation as indicated by the lack of [OII] or H$\alpha$ emission
lines. Therefore, E+A galaxies are interpreted as a post-starburst galaxy -- a
galaxy which truncated starburst suddenly. However, for more than 20 years, the
origin of this post-starburst phenomena remained a mystery. Using the 100,000
galaxy spectra of the Sloan Digital Sky Survey Data Release 1, we tested three
popular explanations to the E+A phenomenon.


title: The Initial Mass Function of GMCs

abstract:
  The properties of GMCs in several Local Group galaxies are quantified and
compared. It is found that the mass spectrum of GMCs varies from galaxy to
galaxy. The variations are significant and do not appear to be the result of
systematic uncertainties. Nevertheless, it appears that all of the GMCs follow
the same size-linewidth and mass-linewidth relations with little scatter. The
power law indices of these relations imply that the GMCs are self-gravitating,
and that the mean surface density of Local Group GMCs is approximately
constant. This, in turn, implies that the mean internal pressure of GMCs is
also constant. If the IMF of stars is determined by a Jeans instability, this
constant internal pressure suggests that the distribution of stellar masses
does not vary significantly in galactic disks when averaged over suitably large
areas. Thus, although the distribution of GMC masses produced by various Local
Group galaxies is quite variable, the large-scale properties of the GMCs is
not.


title: The Baryonic Tully Fisher Relation

abstract:
  We validate the baryonic Tully Fisher (BTF) relation by exploring the Tully
Fish er (TF) and BTF properties of optically and HI-selected disk galaxies. The
data includes galaxies from: Sakai et al. (2000) calibrator sample; McGaugh et
al. (2000: MC2000) I-band sample; and 18 newly acquired HI-selected field dwarf
galaxies observed with the ANU 2.3m telescope and the ATNF Parkes telescope
from Gurovich's thesis sample (2005).
  As in MC2000, we re-cast the TF and BTF relations as relationships between
baryo n mass and W_{20}. First we report some numerical errors in MC2000. Then,
we c alculate weighted bi-variate linear fits to the data, and finally we
compare the fits of the intrinsically fainter dwarfs with the brighter galaxies
of Sakai et al. (2000). With regards to the local calibrator disk galaxies of
Sakai et al. (2000), our results suggest that the BTF relation is indeed
tighter than the T F relation and that the slopes of the BTF relations are
statistically flatter th an the equivalent TF relations. Further, for the
fainter galaxies which include the I-band MCG2000 and HI-selected galaxies of
Gurovich's thesis sample, we calc ulate a break from a simple power law model
because of what appears to be real c osmic scatter. Not withstanding this
point, the BTF models are marginally better models than the equivalent TF ones
with slightly smaller reduced chi^2.


title: The Truncated Disk of CoKu Tau/4

abstract:
  We present a model of a dusty disk with an inner hole which accounts for the
Spitzer Space Telescope Infrared Spectrograph observations of the low-mass
pre-main sequence star CoKu Tau/4. We have modeled the mid-IR spectrum (between
8 and 25 mic) as arising from the inner wall of a disk. Our model disk has an
evacuated inner zone of radius ~ 10 AU, with a dusty inner ``wall'', of
half-height ~ 2 AU, that is illuminated at normal incidence by the central
star. The radiative equilibrium temperature decreases from the inner disk edge
outward through the optically-thick disk; this temperature gradient is
responsible for the emission of the silicate bands at 10 and 20 mic. The
observed spectrum is consistent with being produced by Fe-Mg amorphous glassy
olivine and/or pyroxene, with no evidence of a crystalline component. The
mid-infrared spectrum of CoKu Tau/4 is reminiscent of that of the much older
star TW Hya, where it has been suggested that the significant clearing of its
inner disk is due to planet formation. However, no inner disk remains in CoKu
Tau/4, consistent with the star being a weak-emission (non-accreting) T Tauri
star. The relative youth of CoKu Tau/4 (~ 1 Myr) may indicate much more rapid
planet formation than typically assumed.