title: Dynamics of the Solar Magnetic Network: Two-dimensional MHD Simulations

abstract:
  The aim of this work is to identify the physical processes that occur in the
network and contribute to its dynamics and heating. We model the network as
consisting of individual flux tubes with a non-potential field structure that
are located in intergranular lanes. With a typical horizontal size of 200 km at
the base of the photosphere, they expand upward and merge with their neighbors
at a height of about 600 km. Above a height of approximately 1000 km the
magnetic field starts to become uniform.
  Waves are generated in this medium by means of motions at the lower boundary.
We focus on transverse driving, which generates both fast and slow waves within
a flux tube and acoustic waves at the interface of the tube and the field-free
medium. The acoustic waves at the interface are due to compression of the gas
on one side of the flux tube and expansion on the other. These waves travel
upward along the two sides of the (2D) flux tube and enter it, where they
become longitudinal waves. For impulsive excitation with a time constant of 120
s, we find that a dominant feature is the creation of vortical motions that
propagate upward. We have identified an efficient mechanism for the generation
of longitudinal waves and shock formation in the chromospheric part of the flux
concentration. We examine some broad implications of our results.


title: New Studies of the Pulsar Wind Nebula in the Supernova Remnant CTB 80

abstract:
  We investigated the kinematics of the pulsar wind nebula (PWN) associated
with PSR B1951+32 in the old supernova remnant CTB 80 using the Fabry-Perot
interferometer of the 6m Special Astrophysical Observatory telescope. In
addition to the previously known expansion of the system of bright filaments
with a velocity of 100-200km/s, we detected weak high-velocity features in the
H-alpha line at least up to velocities of 400-450km/s. We analyzed the
morphology of the PWN in the H-alpha, [SII], and [OIII] lines using HST data
and discuss its nature. The shape of the central filamentary shell, which is
determined by the emission in the [OIII] line and in the radio continuum, is
shown to be consistent with the bow-shock model for a significant (about 60
degrees) inclination of the pulsar's velocity vector to the plane of the sky.
In this case, the space velocity of the pulsar is twice higher than its
tangential velocity, i.e., it reaches ~500 km/s, and PSR B1951+32 is the first
pulsar whose line-of-sight velocity (of about 400 km/s) has been estimated from
the PWN observations. The shell-like H-alpha-structures outside the bow shock
front in the east and the west may be associated with both the pulsar's jets
and the pulsar-wind breakthrough due to the layered structure of the extended
CTB 80 shell.


title: Simultaneous Multi-Wavelength Observations of Sgr A*

abstract:
  We observed Sgr A* using the Very Large Array (VLA) and the Giant Metrewave
Radio Telescope (GMRT) at multiple cm and mm wavelengths on 17 June 2003. The
measured flux densities of Sgr A*, together with those obtained from the
Submillimeter Array (SMA) and the Keck II 10 m telescope on the same date, are
used to construct a simultaneous spectrum of Sgr A* from 90 cm to 3.8 $\mu$m.
The simultaneous spectrum shows a spectral break at about 3.6 cm, a possible
signature of synchrotron self-absorption of the strong radio outburst which
occurred near epoch 17 July 2003. At 90 cm, the flux density of Sgr A* is
$0.22\pm0.06$ Jy, suggesting a sharp decrease in flux density at wavelengths
longer than 47 cm. The spectrum at long cm wavelengths appears to be consistent
with free-free absorption by a screen of ionized gas with a cutoff $\sim$100
cm. This cutoff wavelength appears to be three times longer than that of
$\sim$30 cm suggested by Davies, Walsh & Booth based on observations in 1974
and 1975. Our analysis suggests that the flux densities of Sgr A* at
wavelengths longer than 30 cm could be attenuated and modulated by stellar
winds from massive stars close to Sgr A*.


title: The generation of low-energy cosmic rays in molecular clouds

abstract:
  It is argued that if cosmic rays penetrate into molecular clouds, the total
energy they lose can exceed the energy from galactic supernovae shocks. It is
shown that most likely galactic cosmic rays interacting with the surface layers
of molecular clouds are efficiently reflected and do not penetrate into the
cloud interior. Low-energy cosmic rays ($E<1$ GeV) that provide the primary
ionization of the molecular cloud gas can be generated inside such clouds by
multiple shocks arising due to supersonic turbulence.


title:
XMM-Newton observations of two transient millisecond X-ray pulsars in
  quiescence

abstract:
  We report on XMM-Newton observations of two X-ray transient millisecond
pulsars (XRTMSPs). We detected XTE J0929-314 with an unabsorbed luminosity of
\~7x10^{31} erg/s. (0.5-10 keV) at a fiducial distance of 10 kpc. The quiescent
spectrum is consistent with a simple power law spectrum. The upper limit on the
flux from a cooling neutron star atmosphere is about 20% of the total flux. XTE
J1807-294 instead was not detected. We can put an upper limit on the source
quiescent 0.5-10 keV unabsorbed luminosity <4x10^{31} erg/s at 8 kpc. These
observations strenghten the idea that XRTMSPs have quiescent luminosities
significantly lower than classical neutron star transients.


title:
High resolution X-ray spectrum of the accreting binary X-ray pulsar GX
  1+4

abstract:
  We present here high resolution X-ray spectrum of the accreting binary X-ray
pulsar GX 1+4 obtained with the High Energy Transmission Grating (HETG)
instrument of the Chandra X-ray Observatory. This was supplemented by a
simultaneous observation with the Proportional Counter Array (PCA) of the Rossi
X-ray Timing Explorer (RXTE). During this observation, the source was in a
somewhat low intensity state and the pulse profile with both Chandra and RXTE
shows a narrow dip, characteristic of GX 1+4 in medium and low intensity
states. The continuum X-ray spectrum obtained with the HETG and PCA can be
fitted well with a high energy cutoff power-law model with line of sight
absorption. Interestingly, we find that this low state is accompanied by a
relatively small absorption column density. A 6.4 keV narrow emission line with
an equivalent width of 70 eV is clearly detected in the HETG spectrum. The
fluorescence iron line, or at least part of it is produced in the neutral or
lowly ionized iron in the circumstellar material that also causes most of the
line of sight absorption. In the HETG spectrum, we have found evidence for a
weak (equivalent width ~30 eV) emission line at 6.95 keV. This line is
identified as Ly_alpha emission line from hydrogen-like iron and the spectrum
does not show emission lines from helium-like iron. We discuss various emission
regions for the hydrogen-like iron emission line, like gas diffused into the
Alfven sphere or an accretion curtain flowing from the inner accretion disk to
the magnetic poles.


title:
Influence of magnification threshold on pixel lensing optical depth,
  event rate and time scale distributions towards M31

abstract:
  Pixel lensing is the gravitational microlensing of light from unresolved
stars contributing to the luminosity flux collected by a single pixel. A star
must be sufficiently magnified, that is, the lens impact parameter must be less
than a threshold value $u_T$ if the excess photon flux in a pixel is to be
detected over the background. Assuming the parameters of the Isaac Newton
Telescope and typical observing conditions, we present maps in the sky plane
towards M31 of threshold impact parameter, optical depth, event number and
event time scale, analyzing in particular how these quantities depend on $u_T$
in pixel lensing searches. We use an analytical approach consisting of
averaging on $u_T$ and the star column density the optical depth, microlensing
rate and event duration time scale. An overall decrease in the expected optical
depth and event number with respect to the classical microlensing results is
found, particularly towards the high luminosity M31 inner regions. As expected,
pixel lensing events towards the inner region of M31 are mostly due to
self-lensing, while in the outer region dark events dominate even for a 20%
MACHO halo fraction. We also find a far-disk/near-disk asymmetry in the
expected event number, smaller than that found by \cite{Kerins04}. Both for
self and dark lensing events, the pixel lensing time scale we obtain is $\simeq
1 - 7$ days, dark events lasting roughly twice as long as self-lensing events.
The shortest events are found to occur towards the M31 South Semisphere. We
also note that the pixel lensing results depend on $<u_T>$ and $<u_T^{~2}>$
values and ultimately on the observing conditions and telescope capabilities.


title: Soft gamma repeaters outside the Local group

abstract:
  We propose that the best sites to search for SGRs outside the Local group are
galaxies with active massive star formation. Different possibilities to observe
SGR activity from these sites are discussed. In particular we searched for
giant flares from nearby galaxies ($\sim 2$ -- 4 Mpc) M82,
  M83, NGC 253, and NGC 4945 in the BATSE data. No candidates alike giant SGR
flares were found. The absence of such detections implies that the rate of
giant flares with energy release in the initial spike above $0.5 \cdot 10^{44}$
erg is less then 1/25 yr$^{-1}$ in our Galaxy. However, hyperflares similar to
the one of 27 December 2004 can be observed from larger distances.
Nevertheless, we do not see any significant excess of short GRBs from the Virgo
galaxy cluster and from galaxies Arp 299 and NGC 3256 with extremely high star
formation rate. This implies that the galactic rate of hyperflares with energy
release $\sim 10^{46}$ erg is less than $\sim 10^{-3}$ yr$^{-1}$. With this
constraint the fraction of possible extragalactic SGR hyperflares among BATSE
short GRBs should not exceed few percents. We present a list of short GRBs
coincident with galaxies mentioned above, and discuss the possibility that some
of them are SGR giant flares. We propose that the best target for observations
of extragalactic SGR flares by {\it Swift} is the Virgo cluster.


title: Delayed Afterglow Onset Interpreted as Baryon-Poor Viewing Angle

abstract:
  We have suggested previously that baryons in GRB fireballs infiltrate from
the surrounding walls that collimate the fireball. The efficiency $\epsilon_b$
for generating blast energy can then be angle dependent. Delayed onset of
afterglow can be interpreted as being due to a baryon-poor viewing angle.


title: The MAGIC Experiment and Its First Results

abstract:
  With its diameter of 17m, the MAGIC telescope is the largest Cherenkov
detector for gamma ray astrophysics. It is sensitive to photons above an energy
of 30 GeV. MAGIC started operations in October 2003 and is currently taking
data. This report summarizes its main characteristics, its rst results and its
potential for physics.


title: Dark matter detection in gamma astroparticle experiments

abstract:
  The content of matter in the Universe is estimated to be the 27% of its
critical density. It is almost universally accepted that most ot this matter is
non-baryonic. Constraints from primordial nucleosynthesis and cosmic background
radiation measurements impose that the baryonic content of the Universe cannot
exceed the 4% of the critical density, so the nature of the remaining 23% has
yet to be identi ed. In this sense, one of the most promising candidates is
represented by supersymmetric neutralinos. If they exist, they give rise to
relic densities in the required range, and are very well motivated in the
framework of theoretical extensions of the Standard Model of particle physics.
In addition to direct neutralino searches and collider experiments, neutralino
annihilation into gamma rays, neutrinos and synchrotron emission from the
charged products represents a reliable way of detecting these intriguing
particles. The strongest signals are expected to come from the Galactic Center
and from the nearest dwarf spheroidals. Clumps of dark matter in galactic
haloes are well predicted by high resolution cold dark matter numerical
simulations. In this work we present our studies on the gamma-ray emission from
the Galactic Center and from the Draco dwarf spheroidal. We investigate the e
ect of clumpiness on the detection of signals from neutalinos for di erent mass
density pro les. One of the scienti c goals of the MAGIC telescope are just
searches for the stable lightest supersymmetric particle in the di erent
physical scenarios in which they are produed. Assuming MAGIC speci cations, we
draw some conclusions about the potentialities of this telescope in such a kind
of investigation.


title: GMRT HI observations of the Eridanus group of galaxies

abstract:
  The GMRT HI 21cm-line observations of galaxies in the Eridanus group are
presented. The Eridanus group, at a distance of ~23 Mpc, is a loose group of
\~200 galaxies. The group extends more than 10 Mpc in projection. The velocity
dispersion of the galaxies in the group is ~240 km/s. The galaxies are
clustered into different sub-groups. The overall population mix of the group is
30% (E+S0) and 70% (Sp+Irr). The observations of 57 Eridanus galaxies were
carried out with the GMRT for ~200 hour. HI emission was detected from 31
galaxies. The channel rms of ~1.0 mJy beam^{-1} was achieved for most of the
image-cubes made with 4 hour of data. The corresponding HI column density
sensitivity (3-sigma) is ~1x10^{20} cm^{-2} for a velocity-width of ~13.4 km/s.
The 3-sigma detection limit of HI mass is ~1.2x10^{7} M_sun for a line-width of
50 km/s. Total HI images, HI velocity fields, global HI line profiles, HI mass
surface densities, HI disk parameters and HI rotation curves are presented. The
velocity fields are analysed separately for the approaching and the receding
sides of the galaxies. This data will be used to study the HI and the radio
continuum properties, the Tully-Fisher relations, the dark matter halos, and
the kinematical and HI lopsidedness in galaxies.


title: The Blast Energy Efficiency of GRBs

abstract:
  Using data mostly assembled by previous authors, we consider the linear
correlation between the apparent radiative efficiency $\epsilon_{\gamma}$
(defined as the ratio of isotropic equivalent radiative output to inferred
isotropic equivalent kinetic energy of the blast) and $E_{peak}^{\alpha}$ where
$1.4<\alpha<2$, for 17 of 22 GRBs (Lloyd-Ronning and Zhang, 2004). We note in a
quantitative manner that this is consistent with the hypothesis that
$\epsilon_{\gamma}$ and $E_{peak}$ are influenced by viewing angle. We suggest
a more general theoretically derived expression for this correlation that could
be tested with a richer data set. If the reduction in both $\epsilon_{\gamma}$
and $E_{peak}$ is due to viewing angle effects, then the actual radiative
efficiency is $\sim 7$. We also find preliminary evidence (with a small sample)
for a separate class of weak GRB afterglows.


title:
Contribution of pulsars to the gamma-ray background and their
  observation with the space telescopes GLAST and AGILE

abstract:
  Luminosities and uxes of the expected population of galactic gamma-ray
pulsars become foreseeable if physical distributions at birth and evolutive
history are assigned. In this work we estimate the contribution of pulsar uxes
to the gamma-ray background, which has been measured by the EGRET experiment on
board of the CGRO. For pulsar luminosities we select some of the most important
gamma-ray emission models, taking into account both polar cap and outer gap
scenarios. We nd that this contribution strongly depends upon controversial
neutron star birth properties. A comparison between our simulation results and
EGRET data is presented for each model, nding an average contribution of about
10%. In addition, we perform the calculation of the number of new gamma-ray
pulsars detectable by GLAST and AGILE, showing a remarkable di erence between
the two classes of models. Finally, we suggest some improvements in the
numerical code, including more sophisticated galactic m odels and di erent
populations of pulsars like binaries, milliseconds, anomalous pulsars and
magnetars.


title: Neural networks for gamma-hadron separation in MAGIC

abstract:
  Neural networks have proved to be versatile and robust for particle
separation in many experiments related to particle astrophysics. We apply these
techniques to separate gamma rays from hadrons for the MAGIC Cerenkov
Telescope. Two types of neural network architectures have been used for the
classi cation task: one is the MultiLayer Perceptron (MLP) based on supervised
learning, and the other is the Self-Organising Tree Algorithm (SOTA), which is
based on unsupervised learning. We propose a new architecture by combining
these two neural networks types to yield better and faster classi cation
results for our classi cation problem.


title: The HI content of the Eridanus group of galaxies

abstract:
  The HI content of galaxies in the Eridanus group is studied using the GMRT
observations and the HIPASS data. A significant HI deficiency up to a factor of
2-3 is observed in galaxies in the high galaxy density regions. The HI
deficiency in galaxies is observed to be directly correlated with the local
projected galaxy density, and inversely correlated with the line-of-sight
radial velocity. Furthermore, galaxies with larger optical diameters are
predominantly in the lower galaxy density regions. It is suggested that the HI
deficiency in Eridanus is due to tidal interactions. In some galaxies,
evidences of tidal interactions are seen. An important implication is that
significant evolution of galaxies can take place in the group environment. In
the hierarchical way of formation of clusters via mergers of groups, a fraction
of the observed HI deficiency in clusters could have originated in groups. The
co-existence of S0's and severely HI deficient galaxies in the Eridanus group
suggests that galaxy harassment is likely to be an effective mechanism for
transforming spirals to S0's.


title: Grid services for the MAGIC experiment

abstract:
  Exploring signals from the outer space has become an observational science
under fast expansion. On the basis of its advanced technology the MAGIC
telescope is the natural building block for the first large scale ground based
high energy gamma-ray observatory. The low energy threshold for gamma-rays
together with different background sources leads to a considerable amount of
data. The analysis will be done in different institutes spread over Europe.
Therefore MAGIC offers the opportunity to use the Grid technology to setup a
distributed computational and data intensive analysis system with the nowadays
available technology. Benefits of Grid computing for the MAGIC telescope are
presented.


title:
Radio continuum and far-infrared emission from the galaxies in the
  Eridanus group

abstract:
  The Eridanus galaxies follow the well-known radio-FIR correlation. Majority
(70%) of these galaxies have their star formation rates below that of the Milky
Way. The galaxies having a significant excess of radio emission are identified
as low luminosity AGNs based on their radio morphologies obtained from the GMRT
observations. There are no powerful AGNs (L{20cm} > 10^{23} W Hz^{-1}) in the
group. The two most far-infrared and radio luminous galaxies in the group have
optical and HI morphologies suggestive of recent tidal interactions. The
Eridanus group also has two far-infrared luminous but radio-deficient galaxies.
It is believed that these galaxies are observed within a few Myr of the onset
of an intense star formation episode after being quiescent for at least a 100
Myr. The upper end of the radio luminosity distribution of the Eridanus
galaxies (L_{20cm} ~ 10^{22} W Hz^{-1}) is consistent with that of the field
galaxies, other groups, and late-type galaxies in nearby clusters.


title: Data Mining in Gamma Astrophysics Experiments

abstract:
  Data mining techniques, including clustering and classification tasks, for
the automatic information extraction from large datasets are increasingly
demanded in several scientific fields. In particular, in the astrophysical
field, large archives and digital sky surveys with dimensions of 10E12 bytes
currently exist, while in the near future they will reach sizes of the order of
10E15. In this work we propose a multidimensional indexing method to
efficiently query and mine large astrophysical datasets. A novelty detection
algorithm, based on the Support Vector Clustering and using density and
neighborhood information stored in the index structure, is proposed to find
regions of interest in data characterized by isotropic noise. We show an
application of this method for the detection of point sources from a gamma-ray
photon list.


title:
Flux of light antimatter nuclei near earth, induced by Cosmic Rays in
  the Galaxy and in the atmosphere

abstract:
  The fluxes of light antinuclei A<=4 induced near earth by Cosmic Ray intera
ctions with the interstellar matter in the Galaxy and with the Earth
atmosphere, are calculated in a phenomenological framework. The hadronic
production cross section for antinucleons is based on a recent parametrization
of a wide set of accelerator data. The production of light nuclei is calculated
using coalescence models. For the standard coalescence model, the coalescence
radius is fitted to the available experimental data. The non annihilating
inelastic scattering process for the antideuterons is discussed and taken into
account for the first time via a more realistic procedure than used so far for
antiprotons.


title:
Simulating the High Energy Gamma-ray sky seen by the GLAST Large Area
  Telescope

abstract:
  This paper presents the simulation of the GLAST high energy gamma-ray
telescope. The simulation package, written in C++, is based on the Geant4
toolkit, and it is integrated into a general framework used to process events.
A detailed simulation of the electronic signals inside Silicon detectors has
been provided and it is used for the particle tracking, which is handled by a
dedicated software. A unique repository for the geometrical description of the
detector has been realized using the XML language and a C++ library to access
this information has been designed and implemented. A new event display based
on the HepRep protocol was implemented. The full simulation was used to
simulate a full week of GLAST high energy gamma-ray observations. This paper
outlines the contribution developed by the Italian GLAST software group.


title:
Coronal Evolution of the Sun in Time: High-Resolution X-Ray Spectroscopy
  of Solar Analogs with Different Ages

abstract:
  (abridged) We investigate the long-term evolution of X-ray coronae of solar
analogs based on high-resolution X-ray spectroscopy and photometry with
XMM-Newton. Six nearby main-sequence G stars with ages between ~0.1 Gyr and
\~1.6 Gyr and rotation periods between ~1d and 12.4d have been observed. We
derive coronal element abundances and the coronal emission measure distribution
(EMD). The abundances change from an inverse-First Ionization Potential (FIP)
distribution in stars with ages around 0.1 Gyr to a solar-type FIP distribution
in stars at ages of 0.3 Gyr and beyond. The coronal EMDs show shapes
characterized by power-laws on each side of the EMD peak. The latter shifts
from temperatures of about 10 MK in the most rapidly rotating, young stars to
temperatures around 4 MK in the oldest target considered here. The power-law
index on the cooler side of the EMD exceeds expected slopes for static loops,
with typical values being 1.5-3. We interpret this slope with a model in which
the coronal emission is due to a superposition of stochastically occurring
flares, with an occurrence rate that is distributed in radiated energy E as a
power-law, dN/dE ~ E^-a. Our EMDs indicate a ~ 2.2-2.8, in excellent agreement
with values previously derived from light curves of magnetically active stars.
We derive the range of flare energies required to explain the light-curve
modulation. In an overall scenario, we propose that flaring activity plays a
larger role in more active stars. In this model, the higher flare rate is
responsible both for the higher average coronal temperature and the high
coronal X-ray luminosity, two parameters that are indeed found to be
correlated.


title:
Detection of steam in the circumstellar disk around a massive Young
  Stellar Object

abstract:
  We report on the observation of hot water vapor (steam) in the inner AU of a
young massive star located in the star-forming region IRAS 08576-4334. The
water lines are detected in a medium resolution (R=10,000) K-band spectrum
taken by the infrared spectrometer ISAAC mounted on the VLT-ANTU. The water
vapor is at a mean temperature of 1565+/-510 K, cooler than the hot CO found in
the same object, which is at 1660K and the column density is N(H2O)=(2.5 +/-
0.4)x1E18 cm-2. The profile of both H2O and CO lines is best reproduced by the
emission from a Keplerian disk. To interpret the data, we also investigate the
formation of molecules and especially CO and water vapor in the inner hot and
dense part of disks around young high mass stars using a pseudo time-dependent
gas-phase chemical model. Molecules are rapidly photodissociated but this
destruction is compensated by an efficient formation due to fast
neutral-neutral reactions. The ability of CO molecules to self-shield
significantly enhances its abundance. Water molecules are sufficiently abundant
to be detectable. The observed H2O/CO ratio is reproduced by gas at 1600K and
an enhanced UV field over gas density ratio I_UV/nH=1E(-4)- 1E(-6). The
simulations support the presence of CO and H2O molecules in the inner disks
around young massive stars despite the strong UV radiation and show that the OH
radical plays an essential role in hot gas chemistry.


title:
Surface imaging of late-type contact binaries II: Halpha 6563 A emission
  in AE Phoenicis and YY Eridani

abstract:
  We present and discuss the Halpha (6563 A) observations of the contact (W UMa
type) binaries AE Phoenicis and YY Eridani, obtaineded in 1989, 1990 and 1995
with the CAT/CES telescope of the Southern European Observatory (ESO). In
particular, we compare the intrinsic equivalent widths of both components with
the NextGen theoretical models and the saturation limit. We find that the
average Halpha equivalent widths are close to the saturation border and that
the primary components have excess Halpha-emission, indicating enhanced
chromospheric activity. This is compatible with both theoretical and
observational suggestions that the primary is the more magnetically active
component and is filled with (mostly unresolvable) dark spots and associated
chromospheric plages.


title: Underground Searches for Cold Relics of the Early Universe

abstract:
  We have strong evidence on all cosmic scales, from galaxies to the largest
structures ever observed, that there is more matter in the universe than we can
see. Galaxies and clusters would fly apart unless they would be held together
by material which we call dark, because it does not shine in photons. Although
the amount of dark matter and its distribution are fairly well established, we
are clueless regarding its composition. Leading candidates are Weakly
Interacting Massive Particles (WIMPs), which are 'cold' thermal relics of the
Big Bang, ie moving non-relativistically at the time of structure formation.
These particles can be detected via their interaction with nuclei in
deep-underground, low-background detectors. Experiments dedicated to observe
WIMP interactions for the first time reach sensitivities allowing to probe the
parameter space predicted by supersymmetric theories of particle physics.
Current results of high sensitivity direct detection experiments are discussed
and the most promising projects of the future are presented. If a stable new
particle exists at the weak scale, it seems likely to expect a discovery within
this decade.


title: The intermediate-age open clusters Ruprecht 4, Ruprecht 7 and Pismis 15

abstract:
  We report on $BVI$ CCD photometry to $V=22.0$ for 3 fields centered on the
region of the Galactic star clusters Ruprecht~4, Ruprecht~7 and Pismis~15 and
on 3 displaced control fields. Ruprecht~4 and Pismis~15 have never been studied
before, and we provide for the first time estimates of their fundamental
parameters, namely, radial extent, age, distance and reddening. Ruprecht~7
(Berkeley~33) however was studied by Mazur et al. (1993). We find that the
three clusters are all of intermediate age (0.8-1.3 Gyr), and with a
metallicity close to or lower than solar.


title: Prospects for Detection of Catastrophic Collisions in Debris Disks

abstract:
  We investigate the prospects for detecting dust from two body collisions
during the late stages of planet formation at 1-150 AU. We develop an analytic
model to describe the formation of a dusty cloud of debris and use numerical
coagulation and n-body calculations to predict observable signals from these
events. In a minimum mass solar nebula, collisions of 100-1000 km objects at
distances of 3-5 AU or less from the parent star are observable at mid-infrared
wavelengths as bright clumps or rings of dust. At 24 microns, the clumps are
roughly 0.1-1 mag brighter than emission from dust in the background debris
disk. In edge-on systems, dusty clumps produce eclipses with depths of 1.0 mag
or less that last for roughly 100 orbital periods. Large-scale surveys for
transits from exosolar planets, such as Kepler, can plausibly detect these
eclipses and provide important constraints on the terrestrial environment for
ages of less than or roughly 100-300 Myr.


title: A New Milky Way Dwarf Galaxy in Ursa Major

abstract:
  In this Letter, we report the discovery of a new dwarf satellite to the Milky
Way, located at ($\alpha_{2000}, \delta_{2000}$) $=$ (158.72,51.92) in the
constellation of Ursa Major. This object was detected as an overdensity of red,
resolved stars in Sloan Digital Sky Survey data. The color-magnitude diagram of
the Ursa Major dwarf looks remarkably similar to that of Sextans, the lowest
surface brightness Milky Way companion known, but with approximately an order
of magnitude fewer stars. Deeper follow-up imaging confirms this object has an
old and metal-poor stellar population and is $\sim$ 100 kpc away. We roughly
estimate M$_V =$ -6.75 and $r_{1/2} =$ 250 pc for this dwarf. Its luminosity is
several times fainter than the faintest known Milky Way dwarf. However, its
physical size is typical for dSphs. Even though its absolute magnitude and size
are presently quite uncertain, Ursa Major is likely the lowest luminosity and
lowest surface brightness galaxy yet known.


title: Do Large-Scale Inhomogeneities Explain Away Dark Energy?

abstract:
  Recently, new arguments (astro-ph/0501152, hep-th/0503117) for how
corrections from super-Hubble modes can explain the present-day acceleration of
the universe have appeared in the literature. However, in this letter, we argue
that, to second order in spatial gradients, these corrections only amount to a
renormalization of local spatial curvature, and thus cannot account for the
negative deceleration. Moreover, cosmological observations already put severe
bounds on such corrections, at the level of a few percent, while in the context
of inflationary models, these corrections are typically limited to ~ 10^{-5}.
Currently there is no general constraint on the possible correction from higher
order gradient terms, but we argue that such corrections are even more
constrained in the context of inflationary models.


title: Infrared radiation from an extrasolar planet

abstract:
  A class of extrasolar giant planets - the so-called `hot Jupiters' - orbit
within 0.05 AU of their primary stars. These planets should be hot and so emit
detectable infrared radiation. The planet HD 209458b is an ideal candidate for
the detection and characterization of this infrared light because it is
eclipsed by the star. This planet has an anomalously large radius (1.35 times
that of Jupiter), which may be the result of ongoing tidal dissipation, but
this explanation requires a non-zero orbital eccentricity (~0.03), maintained
by interaction with a hypothetical second planet. Here we report detection of
infrared (24 micron) radiation from HD 209458b, by observing the decrement in
flux during secondary eclipse, when the planet passes behind the star. The
planet's 24 micron flux is 55 +/- 10 micro-Jy (1 sigma), with a brightness
temperature of 1130 +/- 150 Kelvins, confirming the predicted heating by
stellar irradiation. The secondary eclipse occurs at the midpoint between
transits of the planet in front of the star (to within +/- 7 min, 1 sigma),
which means that a dynamically significant orbital eccentricity is unlikely.


title: An Axisymmetric Object-Based Search for a Flat Compact Dimension

abstract:
  A method is presented to search for a hypertorus symmetry axis by the
alignment of distant objects. This offers greater sensitivity than previously
proposed object-based methods that rely on accurate true distances. When
applied to the catalog of objects with z > 1, we find no evidence for a compact
dimension. We deduce a lower limit to the compact dimension size D > 0.9 of the
distance to the cosmic horizon. This is consistent with independent constraints
from the recent analysis of the WMAP microwave background data.


title: Classical Novae as a Probe of the Cataclysmic Variable Population

abstract:
  Classical Novae (CNe) are the brightest manifestation of mass transfer onto a
white dwarf in a cataclysmic variable (CV). As such, they are probes of the
mass transfer rate, Mdot, and WD mass, Mwd, in these interacting binaries. Our
calculations of the dependence of the CN ignition mass, Mign, on Mdot and Mwd
yields the recurrence times of these explosions. We show that the observed CNe
orbital period distribution is consistent with the interrupted magnetic braking
evolutionary scenario, where at orbital periods Porb > 3 hr mass transfer is
driven by angular momentum loss via a wind from the companion star and at Porb
< 3 hr by gravitational radiation. About 50% of CNe occur in binaries accreting
at Mdot ~= 10^{-9} Msun/yr with Porb = 3-4 hr, with the remaining 50% split
evenly between Porb longer (higher Mdot) and shorter (lower Mdot) than this.
This resolution of the relative contribution to the CN rate from different CVs
tells us that 3(9)x10^5 CVs with WD mass 1.0(0.6)Msun are needed to produce one
CN per year. Using the K-band specific CN rate measured in external galaxies,
we find a CV birthrate of 2(4)x10^{-4}/yr per 10^{10}Lsun,K, very similar to
the luminosity specific Type Ia supernova rate in elliptical galaxies.
Likewise, we predict that there should be 60-180 CVs for every 10^6Lsun,K in an
old stellar population, similar to the number of X-ray identified CVs in the
globular cluster 47 Tuc, showing no overabundance relative to the field. Using
a two-component steady state model of CV evolution we show that the fraction of
CVs which are magnetic (22%) implies a birthrate of 8% relative to non-magnetic
CVs, similar to the fraction of strongly magnetic field WDs. (abridged)


title: "Missing Link" Clouds in the Southern Galactic Plane Survey

abstract:
  We present an automated routine to search for HI self-absorption features
within the Southern Galactic Plane Survey (SGPS). The data were taken with the
Australia Telescope Compact Array (ATCA) and the Parkes Radio Telescope and
encompass 3 deg by 105 deg of sky in the Galactic plane. We apply our routine
to this entire region and derive spin temperatures and column densities for 70
of the larger HISA complexes, finding spin temperatures ranging from 6-41 K
with HI number densities of a few cm^-3. These `missing link' clouds fill in
the spin temperature and density gaps between dense molecular clouds and
diffuse atomic clouds. We compare the HI emission with 12CO emission and find
that 60% of detected HI self-absorption is correlated in space and in velocity
with a molecular counterpart. This is potentially due to a molecular/atomic gas
transition. We also compare HI self-absorption with Galactic spiral arms and
discuss the possibility of using it as a spiral arm tracer.


title: On the difference between type E and A OH/IR stars

abstract:
  The observed SEDs of a sample of 60 OH/IR stars are fitted using a radiative
transfer model of a dusty envelope. Among the whole sample, 21 stars have
reliable phase-lag distances while the others have less accurate distances.
L*-P,Mlr-P and Mlr-L* relations have been plotted for these stars. It is found
that type E (with emission feature at 10um and type A (with absorption feature
at 10um) OH/IR stars have different L*-P and Mlr-L* relations while both of
them follow a single Mlr-P relation. The type E stars are proven to be located
in the area without large scale dense interstellar medium while the type A
stars are located probably in dense interstellar medium. It is argued here that
this may indicate the two types of OH/IR stars have different chemical
composition or zero age main sequence mass and so evolve in different ways.
This conclusion has reinforced the argument by Chen et al.(2001) who reached a
similar conclusion from the galactic distribution of about 1000 OH/IR stars
with the IRAS low-resolution spectra (LRS).


title: Star formation rates and mass distributions in interacting galaxies

abstract:
  We present a systematic investigation of the star formation rate (hereafter
SFR) in interacting disk galaxies. We determine the dependence of the overall
SFR on different spatial alignments and impact parameters of more than 50
different configurations in combined N-body/hydrodynamic simulations. We also
show mass profiles of the baryonic components. We find that galaxy-galaxy
interactions can enrich the surrounding intergalatic medium with metals very
efficiently up to distances of several 100 kpc. This enrichment can be
explained in terms of indirect processes like thermal driven galactic winds or
direct processes like 'kinetic' spreading of baryonic matter. In the case of
equal mass mergers the direct -kinetic- redistribution of gaseous matter (after
5 Gyr) is less efficient than the environmental enrichment of the same isolated
galaxies by a galactic wind. In the case of non-equal mass mergers however, the
direct -kinetic- process dominates the redistribution of gaseous matter.
Compared to the isolated systems, the integrated star formation rates (ISFRs)
($\int_{t = 0 Gyr}^{t = 5 Gyr}\textnormal{SFR(t)}dt$) in the modelled
interacting galaxies are in extreme cases a factor of 5 higher and on average a
factor of 2 higher in interacting galaxies. Co-rotating and counter-rotating
interactions do not show a common trend for the enhancement of the ISFRs
depending on the interaction being edge-on or face-on. The latter case shows an
increase of the ISFRs for the counter-rotating system of about 100%, whereas
the edge-on counter-rotating case results in a lower increase ($\sim$ 10%).


title: GALEX: Galaxy Evolution Explorer

abstract:
  We review recent scientific results from the Galaxy Evolution Explorer with
special emphasis on star formation in nearby resolved galaxies.


title: Pulsation properties of C stars in the Small Magellanic Cloud

abstract:
  A sample of carbon-rich stars (C-stars) in the Small Magellanic Cloud (SMC)
was selected from the combined 2MASS and DENIS catalogues on the basis of their
$J-K_s$ colour. This sample was extended to include confirmed C--stars from the
Rebeirot et al. (1993) spectroscopic atlas. In this combined sample (N = 1152),
a smaller number (N = 1079) were found to have MACHO observations. For this
sub--sample, light curves were determined and 919 stars were found to have high
quality light-curves with amplitudes of at least 0.05 mag. Of these stars, only
4% have a well--defined single period -- most of these have multiple
well-defined periods, while 15% have highly irregular light--curves. The
distribution of the logarithm of the period versus magnitude, colour, period
ratio (if applicable), and amplitude was analyzed and compared with previous
works. Variable C-stars are distributed in three sequences: B, C and D from
Wood et al. (1999), and do not populate sequences with periods shorter than
$\log P \sim 1.5$. Stellar ages and masses were estimated using stellar
evolutionary models.


title:
Comment on the paper of Jaffe et al (astro-ph/0503213) on evidence of
  vorticity and shear of the Universe

abstract:
  We show that recent results in the paper of Jaffe et al on evidence of
vorticity and shear of the Universe are incorrect. They fit WMAP data with
certain Bianchi model which is known to have a vanishing vorticity. The
performed fit of the shear is not reliable because the respective formula seems
not to be gauge invariant. We suggest a theoretical framework to analyze
asymmetric large scale WMAP data.


title: AGN feedback and gas mixing in the core of NGC 4636

abstract:
  Chandra observations of NGC 4636 show disturbances in the galaxy X-ray halo,
including arm-like high surface brightness features (tentatively identified as
AGN driven shocks) and a possible cavity on the west side of the galaxy core.
We present Chandra and XMM spectral maps of NGC 4636 which confirm the presence
of the cavity and show it to be bounded by the arm features. The maps also
reveal a ~15 kpc wide plume of low temperature, high abundance gas extending
25-30 kpc to the southwest of the galaxy. The cavity appears to be embedded in
this plume, and we interpret the structure as being entrained gas drawn out of
the galaxy core during previous episodes of AGN activity. The end of the plume
is marked by a well defined edge, with significant falls in surface brightness,
temperature and abundance, indicating a boundary between galaxy and
group/cluster gas. This may be evidence that as well as preventing gas cooling
through direct heating, AGN outbursts can produce significant gas mixing,
disturbing the temperature structure of the halo and transporting metals out
from the galaxy into the surrounding intra-group medium.


title: Can Fluffy Dust Alleviate the "Subsolar" Interstellar Abundance Problem?

abstract:
  What might be the most appropriate set of interstellar reference abundances
of chemical elements (both in gas and in dust) relative to hydrogen has been a
subject of much discussion in the past decade. While historically the Sun has
been taken as the reference standard, it has recently been suggested that the
interstellar abundances might be better represented by those of B stars
(because of their young ages) which are just ~60--70% of the widely adopted
solar values (``subsolar''). On the other hand, the most recent estimates of
the solar carbon and oxygen abundances are also close to those of B stars. If
the interstellar abundances are indeed ``subsolar'' like B stars or the
newly-determined solar C,O values, there might be a lack of raw material to
form the dust to account for the interstellar extinction. In literature it has
been argued that this problem could be solved if interstellar grains have a
fluffy, porous structure since fluffy grains are more effective in absorbing
and scattering optical and ultraviolet starlight than compact grains (on a per
unit mass basis). However, we show in this work that, using the Kramers-Kronig
relation, fluffy dust is not able to overcome the abundance shortage problem. A
likely solution is that the abundances of refractory elements in stellar
photospheres may under-represent the composition of the interstellar material
from which stars are formed, resulting either from the possible underestimation
of the degree of heavy-element settling in stellar atmospheres, or from the
incomplete incorporation of heavy elements in stars during the star formation
process.


title:
The Molecular Connection to the FIR-Radio Continuum Correlation in
  Galaxies

abstract:
  We have studied the relationships between the radio continuum (RC) and CO
emission for a set of galaxies selected from the BIMA Survey of Nearby
Galaxies. We find that the global CO-RC correlation is as tight as the global
FIR-RC correlation for the 24 galaxies studied. Within 9 galaxies with ~6
arcsec CO and RC data available, the CO and RC emission is as tightly
correlated as its global value; the radially averaged correlation is nearly
linear, extends over four order of magnitude and holds down to the smallest
linear resolution of the observations, which is ~100 pc. We define qco as the
log of the ratio of the CO to RC flux as a way to characterize the CO-RC
correlation. Combining 6 arcsec pixel-by-pixel comparisons across all sources
yields an average small-scale correlation of qco = 1.1 +/- 0.28; that is, the
spatially resolved correlation has a dispersion that is less than a factor of
2. There are however systematic variations in the CO/RC ratio; the strongest
organized structures in qco tend to be found along spiral arms and on size
scales much larger than the resolution of the observations. We do not measure
any systematic trend in CO/RC ratio as a function of radius in galaxies. The
constancy of the CO/RC ratio stands in contrast to the previously measured
decrease in the FIR/RC ratio as a function of radius in galaxies. We suggest
that the excellent correlation between the CO, RC and FIR emission in galaxies
is a consequence of regulation by hydrostatic pressure; this model links all
three emissions without invoking an explicit dependence on a star formation
scenario.


title:
The ACS Virgo Cluster Survey. VII. Resolving the Connection Between
  Globular Clusters and Ultra-Compact Dwarf Galaxies

abstract:
  We investigate the connection between globular clusters and ultra-compact
dwarf galaxies (UCDs) by examining the properties of several compact objects
associated with M87, all of which were previously classified as globular
clusters. Combining imaging from the Hubble Space Telescope with ground-based
Keck spectroscopy, we find two objects to have half-light radii, velocity
dispersions and mass-to-light ratios that are consistent with the predictions
of population synthesis models for old, metal-rich, luminous globular clusters.
Three other objects are much larger, with half-light radii of approximately
20pc, and have V-band mass-to-light ratios in the range 6-9. These objects,
which we consider to be UCDs, resemble the nuclei of nucleated dwarf elliptical
galaxies in Virgo, having similar mass-to-light ratios, luminosities and
colors. These UCDs are found to obey the extrapolated scaling relations of
galaxies more closely than those of Galactic globular clusters. There appears
to be a transition between the two types of stellar systems at a mass of about
two million solar masses. If the UCDs are gravitationally bound, then we
suggest that the presence of dark matter is the fundamental property
distinguishing globular clusters from UCDs. More than half of the UCD
candidates uncovered in the ACS Virgo Cluster Survey are associated with a
single galaxy -- M87 -- which suggests that proximity to the Virgo center may
be of critical importance for the formation of these objects. These results
show that distinguishing bonafide UCDs from bright globular clusters requires a
careful analysis of their detailed structural and dynamical properties,
particularly their mass-to-light ratios. (ABRIDGED)


title: On the Absorption and Emission Properties of Interstellar Grains

abstract:
  Our current understanding of the absorption and emission properties of
interstellar grains are reviewed. The constraints placed by the Kramers-Kronig
relation on the wavelength-dependence and the maximum allowable quantity of the
dust absorption are discussed. Comparisons of the opacities (mass absorption
coefficients) derived from interstellar dust models with those directly
estimated from observations are presented.


title:
Terrestrial Planet Formation I. The Transition from Oligarchic Growth to
  Chaotic Growth

abstract:
  We use a hybrid, multiannulus, n-body-coagulation code to investigate the
growth of km-sized planetesimals at 0.4-2 AU around a solar-type star. After a
short runaway growth phase, protoplanets with masses of roughly 10^26 g and
larger form throughout the grid. When (i) the mass in these `oligarchs' is
roughly comparable to the mass in planetesimals and (ii) the surface density in
oligarchs exceeds 2-3 g/sq cm at 1 AU, strong dynamical interactions among
oligarchs produce a high merger rate which leads to the formation of several
terrestrial planets. In disks with lower surface density, milder interactions
produce several lower mass planets. In all disks, the planet formation
timescale is roughly 10-100 Myr, similar to estimates derived from the
cratering record and radiometric data.


title: Interstellar Grains -- The 75th Anniversary

abstract:
  The year of 2005 marks the 75th anniversary since Trumpler (1930) provided
the first definitive proof of interstellar grains by demonstrating the
existence of general absorption and reddening of starlight in the galactic
plane. This article reviews our progressive understanding of the nature of
interstellar dust.


title:
Chandra High-Resolution X-ray Spectroscopy of the Fe K Line in the
  Seyfert 1 Galaxy NGC 3783

abstract:
  We report on the results of detailed X-ray spectroscopy of the Fe K region in
the Seyfert 1 galaxy NGC 3783 from five ~170 ks observations with the Chandra
high energy gratings. Monitoring was conducted over an interval of ~125 days in
2001. The combined data constitute the highest signal-to-noise Fe K spectrum
having the best velocity resolution in the Fe K band to date (FWHM ~1860 km/s).
The data show a resolved Fe K line core with a center energy of 6.397 +/- 0.003
keV, consistent with an origin in neutral or lowly ionized Fe, located between
the BLR and NLR, as found by Kaspi et al. (2002). We also find that excess flux
around the base of the Fe K line core can be modeled with either a Compton
scattering ``shoulder'' or an emission line from a relativistic accretion disk,
having an inclination angle of 11 degrees or less. This disk line model is as
good as a Compton-shoulder model for the base of the Fe K line core. In the
latter model, the column density is 7.5 [+2.7,-0.6] x 10^{23} cm^{-2}, which
corresponds to a Thomson optical depth of ~0.60. An intrinsic width of 1500
[+460,-340] km/s FWHM is still required in this model. Moreover, more
complicated scenarios involving both a Compton-shoulder and a disk line cannot
be ruled out. We confirm an absorption feature due to He-like Fe (FWHM = 6405
[+5020,-2670] km/s), found in previous studies.


title: The Warm, Cold and Very Cold Dusty Universe

abstract:
  We are living in a dusty universe: dust is ubiquitously seen in a wide
variety of astrophysical environments, ranging from circumstellar envelopes
around cool red giants to supernova ejecta, from diffuse and dense interstellar
clouds and star-forming regions to debris disks around main-sequence stars,
from comets to interplanetary space to distant galaxies and quasars. In this
review I focus on interstellar grains, with particular emphasis on the
extinction (absorption plus scattering) and emission properties of cold
submicron-sized ``classical'' grains which, in thermal equilibrium with the
ambient interstellar radiation field, obtain a steady-state temperature of
\~15--25K, warm nano-sized (or smaller) "ultrasmall" grains which are, upon
absorption of an energetic photon, transiently heated to temperatures as high
as a few hundred to over 1000K, and the possible existence of a population of
very cold (< 10K) dust. Whether dust grains can really get down to
"temperature" less than the 2.7K cosmic microwave background radiation
temperature will also be discussed. The robustness of the
silicate-graphite-PAHs interstellar dust model is demonstrated by showing that
the infrared emission predicted from this model closely matches that observed
for the Milky Way, the Small Magellanic Cloud, and the ringed Sb galaxy
NGC7331.


title: A Remarkable Low-Mass X-ray Binary within 0.1 pc of the Galactic Center

abstract:
  Recent X-ray and radio observations have identified a transient low-mass
X-ray binary (LMXB) located only 0.1 pc in projection from the Galactic center,
CXOGC J174540.0-290031. In this paper, we report the detailed analysis of X-ray
and infrared observations of the transient and its surroundings. Chandra
bservations detect the source at a flux of F_X = 2e-12 erg cm^-2 s^-1 (2-8
keV). After accounting for absorption both in the interstellar medium and in
material local to the source, the implied luminosity of the source is only L_X
= 4e34 erg/s (2-8 keV; D=8 kpc). However, the diffuse X-ray emission near the
source also brightened by a factor of 2. The enhanced diffuse X-ray emission
lies on top of a known ridge of dust and ionized gas that is visible infrared
images. We interpret the X-ray emission as scattered flux from the outburst,
and determine that the peak luminosity of CXOGC J174540.0-290031 was >2e36
erg/s. We suggest that the relatively small observed flux results from the fact
that the system is observed nearly edge-on, so that the accretion disk
intercepts most of the flux emitted along our line of sight. We compare the
inferred peak X-ray luminosity to that of the radio jet. The ratio of the X-ray
to radio luminosities, L_X/L_R<1e4, is considerably smaller than in other known
LMXBs (> 1e5). This is probably because the jets are radiating with unusually
high efficiency at the point where they impact the surrounding interstellar
medium. This hypothesis is supported by a comparison with mid-infrared images
of the surrounding dust. Finally, we find that the minimum power required to
produce the jet, L_jet~1e37 erg/s, is comparable to the inferred peak X-ray
luminosity. This is the most direct evidence yet obtained that LMXBs accreting
at low rates release about half of their energy as jets.


title:
SCUBA sub-millimeter observations of gamma-ray bursters III. GRB 030329:
  The brightest sub-millimeter afterglow to date

abstract:
  We discuss our ongoing program of Target of Opportunity (ToO) sub-millimeter
observations of gamma-ray bursts (GRBs) using the Sub-millimetre Common-User
Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT). In this
paper, we present all the ToO observations of GRB 030329. This was by far the
brightest sub-millimeter afterglow seen to date. The flux density at 850
microns was approximately constant up to a break that took place ~7 days after
the burst. This was consistent with being a jet break. The 850 micron results
agree with those at longer wavelengths that show a brighter flux ~7 days after
the burst, right at the time of the break. No short-lived large-scale
brightenings were detected in the sub-millimeter light curve. However, the 850
micron light curve may have had a drop <~ 16 days after the burst. The peak of
the afterglow emission was at ~90 GHz in the days before the break in the light
curve. A simple modeling is consistent with the spectral indices remaining the
same as the afterglow evolved, with the breaks in the spectrum moving to longer
wavelengths at later times and the flux at the peak falling. No significant
sub-millimeter emission was detected from the host galaxy.


title:
SCUBA sub-millimeter observations of gamma-ray bursters IV. GRB 021004,
  021211, 030115, 030226, 041006

abstract:
  We discuss our ongoing program of Target of Opportunity (ToO) sub-millimeter
observations of gamma-ray bursts (GRBs) using the Sub-millimetre Common-User
Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT). In this
paper, we present the ToO observations of GRBs 021004, 021211, 030115, 030226,
and 041006. The observations of GRBs 021004, 021211, 030226, and 041006 all
started within ~1 day of the burst, but did not detect any significant
sub-millimeter emission from the reverse shock and/or afterglow. These
observations put some constraints on the models for the early emission,
although the generally poor observing conditions and/or the faintness of these
afterglows at other wavelengths limit the inferences that can be drawn from
these lack of detections. However, these observations demonstrate that SCUBA
can perform rapid observations of GRBs, and provide encouragement for future
observations in the Swift era. None of these GRBs had significant
sub-millimeter emission from their host galaxies. This adds to the indication
that GRBs are not closely linked to the most luminous dusty star-forming
galaxies.


title:
A Photometric Diagnostic to Aid in the Identification of Transiting
  Extra-Solar Planets

abstract:
  One of the obstacles in the search for exoplanets via transits is the large
number of candidates that must be followed up, few of which ultimately prove to
be exoplanets. Any method that could make this process more efficient by
somehow identifying the best candidates and eliminating the worst would
therefore be very useful. Seager and Mallen-Ornelas (2003) demonstrated that it
was possible to discern between blends and exoplanets using only the
photometric characteristics of the transits. However, these techniques are
critically dependent on the shape of the transit, characterization of which
requires very high precision photometry of a sort that is atypical for
candidates identified from transit searches. We present a method relying only
on transit duration, depth, and period, which require much less precise
photometry to determine accurately. The numerical tool we derive, the exoplanet
diagnostic \eta, is intended to identify the subset of candidates from a
transit search that is most likely to contain exoplanets, and thus most worthy
of subsequent follow-up studies. The effectiveness of the diagnostic is
demonstrated with its success in separating modeled exoplanetary transits and
interlopers, and by applying it to actual OGLE transit candidates.


title: On Quasilinear Perpendicular Diffusion

abstract:
  Quasilinear perpendicular diffusion of charged particles in fluctuating
electromagnetic fields is the focus of this paper. A general transport
parameter for perpendicular diffusion is presented being valid for an arbitrary
turbulence geometry and a plasma wave dispersion relation varying arbitrarily
in wavevector. The new diffusion coefficient is evaluated in detail for slab
turbulence geometry for two special cases: (1) Alfv\'enic turbulence and (2)
dynamical magnetic turbulence. Furthermore, perpendicular diffusion in 2D
geometry is considered for a purely dynamical magnetic turbulence. The
derivations and numerical calculations presented here cast serious doubts on
the applicability of quasilinear theory for perpendicular diffusion.
Furthermore, they emphasize that nonlinear effects play a crucial role in the
context of perpendicular diffusion.


title: The Effects of Clumping on Derived Abundances in H II Regions

abstract:
  We have compared Monte Carlo photoionization models of H II regions with a
uniform density distribution with models with the same central stars and
chemical compositions but with 3-D hierarchical clumps. We compare the
abundances of He, N, O, Ne, and S obtained from emission line strengths and [O
III] and [N II] temperatures to those in our models. We consider stellar
temperatures in the range 37.5 -- 45kK and ionizing luminosities from 10^{48}
to 10^{51} photons/s.
  Clumped models have different ionic abundances than uniform. For hot stars,
He^0/He^+ is 2 -- 3%, much larger than with uniform models. This amount of He I
is independent of metallicity and so impacts the determination of the
primordial abundance of He. The total abundances of O, Ne, and S obtained by
the usual methods of analysis, using T([OIII) for high stages of ionization and
T([NII]) for low, are about as accurate for clumped models as for uniform and
within about 20% of the true values. If T([OIII]) is used for analyzing all
ions, the derived (O/H) is 40 to 60% too large for cool stars but is good for
hot stars. Uniform models have similar errors, so the clumping does not change
the accuracy of abundance analysis.
  The physical causes of the ionic abundance errors are present in real
nebulae. In clumped models, helium ionizing radiation from zones of high
ionization (low He^0 and low UV opacity) can penetrate nearby regions near the
edge of the ionized zone. This effect allows He^0 to absorb more stellar
photons than in uniform or radially symmetrical geometries. In turn, these
absorptions compete with O+, etc., for those energetic stellar photons.


title: Cosmological Constraints on Newton's Constant

abstract:
  We present cosmological constraints on deviations of Newton's constant at
large scales, analyzing latest cosmic microwave background (CMB) anisotropies
and primordial abundances of light elements synthesized by big bang
nucleosynthesis (BBN). BBN limits the possible deviation at typical scales of
BBN epoch, say at 10^8 \sim 10^12m, to lie between -5% and +1% of the
experimental value, and CMB restricts the deviation at larger scales 10^2 \sim
10^9pc to be between -26% and +66% at the 2\sigma confidence level. The
cosmological constraints are compared with the astronomical one from the
evolution of isochrone of globular clusters.


title: Modeling the resonant planetary system GJ876

abstract:
  The two planets about the star GJ 876 appear to have undergone extensive
migration from their point of origin in the protoplanetary disk -- both because
of their close proximity to the star (30 and 60 day orbital periods) and
because of their occupying three stable orbital resonances at the 2:1
mean-motion commensurability. The resonances were most likely established by
converging differential migration of the planets leading to capture into the
resonances. A problem with this scenario is that continued migration of the
system while it is trapped in the resonances leads to orbital eccentricities
that rapidly exceed the observational upper limits of e_1 = 0.31 and e_2 =
0.05. As seen in forced 3-body simulations, lower eccentricities would persist
during migration only for an applied eccentricity damping.
  Here we explore the evolution of the GJ 876 system using two-dimensional
hydrodynamical simulations that include viscous heating and radiative effects.
We find that a hydrodynamic evolution within the resonance, where only the
outer planet interacts with the disk, always rapidly leads to large values of
eccentricities that exceed those observed.
  Only if mass is removed from the disk on a time scale of the order of the
migration time scale (before there has been extensive migration after capture),
as might occur for photoevaporation in the late phases of planet formation, can
we end up with eccentricities that are consistent with the observations.


title: Transit Lightcurve Signatures of Artificial Objects

abstract:
  The forthcoming space missions, able to detect Earth-like planets by the
transit method, will a fortiori also be able to detect the transit of
artificial planet-size objects. Multiple artificial objects would produce
lightcurves easily distinguishable from natural transits. If only one
artificial object transits, detecting its artificial nature becomes more
difficult. We discuss the case of three different objects (triangle, 2-screen,
louver-like 6-screen) and show that they have a transit lightcurve
distinguishable from the transit of natural planets, either spherical or
oblate, although an ambiguity with the transit of a ringed planet exists in
some cases. We show that transits, especially in the case of multiple
artificial objects, could be used for the emission of attention-getting
signals, with a sky coverage comparable to the laser pulse method. The large
number of expected planets (several hundreds) to be discovered by the transit
method by next space missions will allow to test these ideas.


title:
The Cluster of Galaxies Surrounding Cygnus A II: New Velocities and a
  Dynamical Model

abstract:
  We have spectroscopically identified 77 new members of the Cygnus A cluster,
bringing the total to 118 galaxies consistent with cluster membership. We use
these data combined with the results from X-rays to deduce a dynamical model
for the system. The data are consistent with a cluster-cluster merger viewed at
a projection angle of 30-45 degrees, 0.2-0.6 Gyr prior to core passage. We
estimate the richness of the combined cluster system at Abell richness class 2
or greater, suggesting the merger of two richness class 1 clusters.


title:
Can superhorizon cosmological perturbations explain the acceleration of
  the universe?

abstract:
  We investigate the recent suggestions by Barausse et al. (astro-ph/0501152)
and Kolb et al. (hep-th/0503117) that the acceleration of the universe could be
explained by large superhorizon fluctuations generated by inflation. We show
that no acceleration can be produced by this mechanism. We begin by showing how
the application of Raychaudhuri equation to inhomogeneous cosmologies results
in several ``no go'' theorems for accelerated expansion. Next we derive an
exact solution for a specific case of initial perturbations, for which
application of the Kolb et al. expressions leads to an acceleration, while the
exact solution reveals that no acceleration is present. We show that the
discrepancy can be traced to higher order terms that were dropped in the Kolb
et al. analysis. We proceed with the analysis of initial value formulation of
general relativity to argue that causality severely limits what observable
effects can be derived from superhorizon perturbations. By constructing a
Riemann normal coordinate system on initial slice we show that no infrared
divergence terms arise in this coordinate system. Thus any divergences found
previously can be eliminated by a local rescaling of coordinates and are
unobservable. We perform an explicit analysis of the variance of the
deceleration parameter for the case of single field inflation using usual
coordinates and show that the infrared divergent terms found by Barausse et al.
and Kolb et al. cancel against several additional terms not considered in their
analysis. Finally, we argue that introducing isocurvature perturbations does
not alter our conclusion that the accelerating expansion of the universe cannot
be explained by superhorizon modes.


title: Beyond the CDMS-II Dark Matter Search: SuperCDMS

abstract:
  Presently the CDMS-II collaboration's Weakly Interacting Massive Particle
(WIMP) search at the Soudan Underground Laboratory sets the most stringent
exclusion limits of any WIMP cold dark matter direct-detection experiment. To
extend our reach further, to WIMP-nucleon cross sections in the range $10^{-46}
- 10^{-44}$cm$^2$, we propose SuperCDMS, which would take advantage of a very
deep site. One promising site is the recently approved SNOLab facility in
Canada. In this paper we will present our overall plan, identify primary
issues, and set the goals that need to be met prior to embarking upon each
phase of SuperCDMS.


title:
Effects of Gravitational Evolution, Biasing, and Redshift Space
  Distortion on Topology

abstract:
  We have studied the dependence of topology of large scale structure on
tracer, gravitational evolution, redshift space distortion, and cosmology. A
series of large N-body simulations of the $\Lambda$CDM and SCDM models that
have evolved 1.1 or 8.6 billion particles, are used in the study. Evolution of
the genus statistic, used as a topology measure, from redshift 8 to 0 is
accurately calculated over a wide range of smoothing scales using the
simulations. The tracers of large scale structure considered are the CDM
matter, biased peaks in the initial density field, dark halos, and `galaxies'
populating the dark halos in accordance with a Halo Occupation Distribution
(HOD) model.
  We have found that the effects of biasing, gravitational evolution, and
initial conditions on topology of large scale structure are all comparable. The
redshift space distortion effects are relatively small down to about 5
$h^{-1}$Mpc for all tracers except for the high threshold part of the genus
curve. The gravitational effects are found to be well-modeled by the analytic
perturbation theory when the CDM matter distribution is considered. But the
direction of gravitational evolution of topology can be even reversed for
different tracers. For example, the shift parameter of the genus curve evolves
in opposite directions for matter and HOD `galaxies' at large scales. At small
scales there are interesting deviations of the genus curve of dark halos and
`galaxies' from that of matter in our initially Gaussian simulations. The
deviations should be understood as due to combined effects of gravitational
evolution and biasing.


title: Confinement-Driven Spatial Variations in the Cosmic Ray Flux

abstract:
  Low-energy cosmic rays (CRs) are confined by self-generated MHD waves in the
mostly neutral ISM. We show that the CR transport equation can be expressed as
a continuity equation for the CR number density involving an effective
convection velocity. Assuming balance between wave growth and ion-neutral
damping, this equation gives a steady-state condition n_cr ~ n_i^1/2 up to a
critical density for free streaming. This relation naturally accounts for the
heretofore unexplained difference in CR ionization rates derived for dense
diffuse clouds (McCall et al. 2003) and dark clouds, and predicts large spatial
variations in the CR heating rate and pressure.


title: Crowded field 3D spectroscopy of LBV candidates in M33

abstract:
  We present integral field spectroscopy of the LBV candidate stars B416 and
v532 in the local group galaxy M33. B416 is surrounded by an elongated
ring-like nebula, which has a projected radius of 20x30 pc. From the datacube
we create ionization and radial velocity maps of the nebula. The excitation of
the gas decreases towards the outer part of the ring, while the inner part of
the nebula is filled with a more excited gas. In the EW direction the ring is
seen to expand with a maximum projected velocity amplitude of about 40 km/s.
The eastern part approaches the observer. We estimate the nebula dynamical
lifetime 8*10E5 years. It could be a residual MS bubble, which indicates a
main-sequence or pre-LBV status of the star. We classify B416 as an "iron star"
or B[e]-supergiant. In v532 an elongated nebula has been marginally detected.
The total projected size of the nebula along the main axis is 30 pc, and the
total radial velocity gradient is 44+/-11 km/s. v532 exhibits both strong
photometric and spectral variability. At the time of our observations it was in
an intermediate brightness state with a rich nitrogen spectrum. We classify
v532 as an LBV, showing LBV <-> Ofpe/WN transitions. We stress the importance
of integral field spectroscopy as the optimal technique for studying nebulae
and the evolution of LBV-like stars in nearby galaxies.


title:
H-D Substitution in Interstellar Solid Methanol: A Key Route for D
  Enrichment

abstract:
  Deuterium enrichment of interstellar methanol is reproduced experimentally
for the first time via grain-surface H-D substitution in solid methanol at an
atomic D/H ratio of 0.1. Although previous gas-grain models successfully
reproduce the deuterium enrichments observed in interstellar methanol molecules
(D/H of up to 0.4, compared to the cosmic ratio of $\sim 10^{-5})$, the models
exclusively focus on deuterium fractionation resulting from the successive
addition of atomic hydrogen/deuterium on CO. The mechanism proposed here
represents a key route for deuterium enrichment that reproduces the high
observed abundances of deuterated methanol, including multiple deuterations.


title:
Origin of E+A galaxies: I. Physical properties of E+A's formed from
  galaxy merging and interaction

abstract:
  We investigate the structural, kinematical, and spectrophotometric properties
of ``E+A'' galaxies -- those with strong Balmer absorption lines but no
significant [OII] emission -- using numerical simulations combined with stellar
population synthesis codes. We particularly focus on the two-dimensional (2D)
distributions of line-of-sight velocity, velocity dispersion, colors, line
index in E+A galaxies formed via the interaction and merging of two gas-rich
spirals. Our numerical simulations demonstrate that E+A elliptical galaxies
formed by major galaxy merging have positive radial color gradients and
negative radial H$\delta$ gradients by virtue of their central poststarburst
populations. Furthermore, we show that the projected kinematical and
spectroscopic properties of the simulated E+A galaxies can be remarkably
different for different major merger models. For example, the simulated E+A
ellipticals with kinematically decoupled cores clearly show regions of strong
H$\delta$ absorption which are very flattened, with differences in rotation and
velocity dispersion between the old and young stars. E+A ellipticals are highly
likely to show more rapid rotation and a smaller central velocity dispersion in
young stars than in old ones.We also provide specific predictions on the
structural, kinematical, and spectrophotometric properties of young globular
cluster systems in E+A's. Based on these results, we discuss the importance of
spatially resolved, integral field unit spectroscopy on large (8-10m)
ground-based telescopes in confirming the formation of kinematically distinct
cores in elliptical galaxies produced via dissipative merging and determining
the most probable physical mechanism(s) for E+A formation with disky and
spheroidal morphologies.


title:
Detailed analysis of open clusters: a mass function break and evidence
  of a fundamental plane

abstract:
  We derive photometric, structural and dynamical evolution-related parameters
of 11 nearby open clusters with ages in the range 70 Myr to 7 Gyr and masses in
the range $\approx400$ \ms to $\approx5 300$ \ms. We search for relations of
structural and evolutionary parameters with age and Galactocentric distance.
The main results for the present sample are: {\em (i)} cluster size correlates
both with age and Galactocentric distance; {\em (ii)} because of size and mass
scaling, core and limiting radii, and core and overall mass correlate; {\em
(iii)} massive ($\rm m\geq1 000$ \ms) and less-massive clusters follow separate
correlation paths on the plane core radius and overall mass; {\em (iv)} MF
slopes of massive clusters are restricted to a narrow range, while those of the
less-massive ones distribute over a wider range. Core and overall MF flattening
is related to the ratio ($\tau$) of age to relaxation time. For large values of
$\tau$ the effects of large-scale mass segregation and low-mass stars
evaporation can be observed in the MFs. In this sense, $\tau$ appears to
characterize the evolutionary state of the clusters. We conclude that
appreciable slope flattenings in the overall MFs of the less-massive clusters
take $\sim6$ times longer to occur than in the core, while in the massive
clusters they take a time $\sim13$ times longer. We investigate cluster
parameters equivalent to those determining the fundamental plane of
ellipticals. These parameters are: overall mass, projected mass density and
core radius. We conclude that in the present sample there is evidence of a
fundamental plane.


title: Evidence for a Starburst within 9 pc of the Active Nucleus of NGC 1097

abstract:
  We report evidence for a recent burst of star formation located within 9 pc
of the active nucleus of NGC 1097. The observational signatures of the
starburst include UV absorption lines and continuum emission from young stars
observed in a small-aperture HST spectrum. The burst is a few times 10^6 yr
old, has a mass of approximately 10^6 solar masses, an observed luminosity of
1.5 x 10^7 solar luminosities and is obscured by approximately 3 visual
magnitudes. The importance of this finding is two-fold: (1) the proximity of
the starburst to the active nucleus and thus possible association with it; (2)
its obscuration by and apparent association with a dusty absorbing medium,
while the broad emission lines appear unobscured, suggesting that the starburst
could be embedded in a circumnuclear torus as predicted in the Unified Model of
active galactic nuclei.


title:
A Compiled Catalogue of Spectroscopically Determined Elemental
  Abundances for Stars with Accurate Parallaxes. I.Magnesium

abstract:
  We present a compiled catalogue of effective temperatures, surface gravities,
iron and magnesium abundances, distances, velocity components, and orbital
elements for stars in the solar neighborhood. The atmospheric parameters and
iron abundances are averages of published values derived from model synthetic
spectra for a total of about 2000 values in 80 publications. Our relative
magnesium abundances were found from 1412 values in 31 publications for 876
dwarfs and subgiants using a three-step iteration averaging procedure, with
weights assigned to each source of data as well as to each individual
determination and taking into account systematic deviations of each scale
relative to the reduced mean scale. The estimated assumed completeness for data
sources containing more than five stars, up to late December 2003, exceeds 90%.
For the vast majority of stars in the catalogue, the spatial velocity
components were derived from modern high-precision astrometric observations,
and their Galactic orbit elements were computed using a three-component model
of the Galaxy, consisting of a disk, a bulge, and a massive extended halo.


title:
The HST/ACS Grism Parallel Survey: II. First Results and a Catalog of
  Faint Emission-Line Galaxies at z < 1.6

abstract:
  We present the first results from the HST/ACS Grism Parallel Survey, a large
program obtaining deep, slitless ACS grism spectroscopy of high-latitude HST
parallel fields. We report on 11 high Galactic latitude fields here, each with
grism integration times >12 ks. We identify 601 compact emission line galaxies
at z < 1.6, reaching emission lines to a flux limit of > 5 E-18 ergs/cm^2/s (3
sigma). We determine redshifts by cross correlation of the target spectra with
template spectra, followed by visual inspection. We measure star formation
rates from the observed [OII] 3727, [OIII] 5007 and Halpha line fluxes.
Follow-up observations with the Keck telescope of one of the survey fields
confirms our classification and redshifts with sigma(z)~0.02. This is one of
the deepest emission line surveys to date, covering a total area of 121
arcmin^2. The rough estimate of the co-moving number density of emission-line
galaxies in our survey at 0.3 < z < 1.3 is ~4.5 E-3 h^{-3}_70 Mpc^{-3}. We
reach deeper into the emission-line luminosity function than either the STIS or
NICMOS grism parallel surveys, finding an apparent space density of emission
line galaxies several times higher than those surveys. Because of the ACS high
spatial resolution, our survey is very sensitive to faint, compact galaxies
with strong emission lines and weak continua. The ACS grism survey provides the
co-moving star formation density at z < 1.6 at a high level of completeness.


title: On the Origin of the Eccentricities of Extrasolar Planets

abstract:
  We develop a phenomenological theory that aims to account for the origin of
the large eccentricities of extrasolar planets and that of the small
eccentricities in the solar system, the preference for apsidal alignment in
non-resonant multiplanet systems, and the origin of the similarities in the
eccentricity distribution of extra-solar planets and that of spectroscopic
binary stars. We show that if a physical process is weakly dependent on the
local dynamics of the companion and imparts a small relative acceleration to
the star-companion system, the eccentricity of the companion's orbit is excited
to large values depending on the direction and duration of acceleration. A
natural candidate for such processes are asymmetric stellar jets and star-disk
winds. When the acceleration originates from a precessing jet, large
eccentricities can be excited by the resonance of the jet's precession
frequency with the induced acceleration's excitation frequency even for nearly
perpendicular jets. Precession also reduces the eccentricity amplitude far
inside the resonance radius. The acceleration's strength is best constrained in
multiplanet systems because of the companions' mutual gravitational
perturbations, while the acceleration's duration is bounded by the condition
that the residual velocity imparted to the star is smaller than the stellar
velocity dispersion in the Galaxy. In the outer parts of the star-companion
system where the acceleration excitation time is comparable to or smaller than
the orbital period, significant radial migration takes place which may have
important consequences for the dynamics of the minor body populations in the
solar system. The theory is illustrated with the $\upsilon$ Andromedae binary
system.


title: Galactic Globular Cluster Relative Ages. II

abstract:
  We present accurate relative ages for a sample of 55 Galactic globular
clusters. The ages have been obtained by measuring the difference between the
horizontal branch and the turnoff in two, internally photometrically
homogeneous databases. The mutual consistency of the two data sets has been
assessed by comparing the ages of 16 globular clusters in common between the
two databases. We have also investigated the consistency of our relative age
determination within the recent stellar model framework. All clusters with
[Fe/H]<-1.7 are found to be old, and coeval, with the possible exception of two
objects, which are marginally younger. The age dispersion for the metal poor
clusters is 0.6 Gyr (rms), consistent with a null age dispersion. Intermediate
metallicity clusters (-1.7<[Fe/H]<-0.8) are on average 1.5 Gyr younger than the
metal poor ones, with an age dispersion of 1.0 Gyr (rms), and a total age range
of ~3 Gyr. About 15% of the intermediate metallicity clusters are coeval with
the oldest clusters. All the clusters with [Fe/H]>-0.8 are ~1 Gyr younger than
the most metal poor ones, with a relatively small age dispersion, though the
metal rich sample is still too small to allow firmer conclusions. There is no
correlation of the cluster age with the Galactocentric distance. We briefly
discuss the implication of these observational results for the formation
history of the Galaxy.


title: Probing MACHOs Toward the Galactic Bulge

abstract:
  If the massive compact halo object (MACHO) fraction of the Galactic dark halo
is f ~ 20% as suggested by some microlensing experiments, then about 1.2% of
lensing events toward the Galactic bulge are due to MACHOs. For the 40% of
these that lie nearby (D_l < 4 kpc), measurement of their distance D_l would
distinguish them from bulge lenses, while measurement of their transverse
velocity v_l would distinguish them from disk lenses. Hence, it would be
possible to identify about 0.5%(f/20%) of all events as due to MACHOs. I show
that a planned experiment using the Space Interferometry Mission (SIM
PlanetQuest) could thereby detect 1 or 2 such events. This is at the margin of
what is required because of a small, but non-negligible background from
spheroid stars.


title: Dissipationless Merging and the Assembly of Central Galaxies

abstract:
  We reanalyze the galaxy-mass correlation function measured by the Sloan
Digital Sky Survey to obtain host dark matter halo masses at galaxy and galaxy
group scales. We extend the data to galaxy clusters in the 2MASS catalog and
study the relation between central galaxy luminosity and halo mass. While the
central galaxy luminosity scales as ~M^{0.7-0.8} at low masses, the relation
flattens to ~M^{<0.3} above ~4x10^{13} M_sun. The total luminosity of galaxies
in the halo, however, continues to grow as a power-law ~M^{0.8-0.9}. Starting
from the hypothesis that the central galaxies grow by merging ("galactic
cannibalism"), we develop a simple model for the evolution of their
luminosities as a consequence of the accretion of satellite galaxies. The
luminosity-mass relation flattens when the time scale on which dynamical
friction induces orbital decay in the satellite galaxies exceeds the age of the
dark matter halo. Then, the growth of the central galaxy is suppressed as it
can cannibalize only the rare, massive satellite galaxies. The model takes the
dependence of the total luminosity of galaxies in a halo on its mass and the
global galaxy luminosity function as input, and reproduces the observed central
galaxy luminosity-mass relation over three decades in halo mass,
(10^{12}-10^{15}) M_sun.
  The success of the model suggests that gas cooling and subsequent star
formation did not play an important role in the final assembly of central
galaxies from sub-L_star precursors.


title:
Evolution of the Near-Infrared Tully-Fisher Relation: Constraints on the
  Relationship Between the Stellar and Total Masses of Disk Galaxies since z=1

abstract:
  Using a combination of Keck spectroscopy and near-infrared imaging, we
investigate the K-band and stellar mass Tully-Fisher relation for 101 disk
galaxies at 0.2 < z < 1.2, with the goal of placing the first observational
constraints on the assembly history of halo and stellar mass. Our main result
is a lack of evolution in either the K-band or stellar mass Tully-Fisher
relation from z = 0 - 1.2. Furthermore, although our sample is not
statistically complete, we consider it suitable for an initial investigation of
how the fraction of total mass that has condensed into stars is distributed
with both redshift and total halo mass. We calculate stellar masses from
optical and near-infrared photometry and total masses from maximum rotational
velocities and disk scale lengths, utilizing a range of model relationships
derived analytically and from simulations. We find that the stellar/total mass
distribution and stellar-mass Tully-Fisher relation for z > 0.7 disks is
similar to that at lower redshift, suggesting that baryonic mass is accreted by
disks along with dark matter at z < 1, and that disk galaxy formation at z < 1
is hierarchical in nature. We briefly discuss the evolutionary trends expected
in conventional structure formation models and the implications of extending
such a study to much larger samples.


title:
Mean JHK Magnitudes of Fundamental-Mode Cepheids from Single-Epoch
  Observations

abstract:
  We present an empirical method for converting single-point near-infrared J,
H, and K measurements of fundamental-mode Cepheids to mean magnitudes, using
complete light curves in V or I bands. The algorithm is based on the template
light curves in the near-infrared bandpasses. The mean uncertainty of the
method is estimated to about 0.03 mag, which is smaller than the uncertainties
obtained in other approaches to the problem in the literature.


title: H2CO and CH3OH abundances in the envelopes around low-mass protostars

abstract:
  This paper presents the third in a series of single-dish studies of molecular
abundances in the envelopes around a large sample of 18 low-mass pre- and
protostellar objects. It focuses on typical grain mantle products and organic
molecules, including H2CO, CH3OH and CH3CN. With a few exceptions, all H2CO
lines can be fit by constant abundances of 7e(-11)-8e(-9) throughout the
envelopes if ortho- and para lines are considered independently. The current
observational dataset does not require a large H2CO abundance enhancement in
the inner warm regions, but this can also not be ruled out. Through comparison
of the H2CO abundances of the entire sample, the H2CO ortho-para ratio is
constrained to be 1.6+/-0.3 consistent with thermalization on grains at
temperatures of 10-15 K. The H2CO abundances can be related to the empirical
chemical network established on the basis of our previously reported survey of
other species and is found to be closely correlated with that of the
nitrogen-bearing molecules. These correlations reflect the freeze-out of
molecules at low temperatures and high densities. An improved fit to the data
is obtained with a `drop' abundance structure in which the abundance decrease
when the temperature is lower than the evaporation temperature and the density
high enough so that the timescale for depletion is less than the lifetime of
the core. The derived abundance structures for CH3OH are consistent with a
scenario where CH3OH probes the action of compact outflows on the envelopes,
which is further supported by comparison to high frequency, high excitation CS
J=10-9 and HDO line profiles. The extent to which the outflow dominates the
abundance enhancements compared with the passively heated inner envelope
depends on the filling factors of the two components in the observing beam.


title: The Classical Gravitational N-Body Problem

abstract:
  Let a number, N, of particles interact classically through Newton's Laws of
Motion and Newton's inverse square Law of Gravitation. The resulting equations
of motion provide an approximate mathematical model with numerous applications
in astrophysics, including the motion of the moon and other bodies in the Solar
System (planets, asteroids, comets and meteor particles); stars in stellar
systems ranging from binary and other multiple stars to star clusters and
galaxies; and the motion of dark matter particles in cosmology. For N=1 and N=2
the equations can be solved analytically. The case N=3 provides one of the
richest of all unsolved dynamical problems -- the general three-body problem.
For problems dominated by one massive body, as in many planetary problems,
approximate methods based on perturbation expansions have been developed. In
stellar dynamics, astrophysicists have developed numerous numerical and
theoretical approaches to the problem for larger values of N, including
treatments based on the Boltzmann equation and the Fokker-Planck equation; such
N-body systems can also be modelled as self-gravitating gases, and
thermodynamic insights underpin much of our qualitative understanding.


title: Cool White Dwarfs in the Sloan Digital Sky Survey

abstract:
  A reduced proper motion diagram utilizing Sloan Digital Sky Survey (SDSS)
photometry and astrometry and USNO-B plate astrometry is used to separate cool
white dwarf candidates from metal-weak, high-velocity main sequence Population
II stars (subdwarfs) in the SDSS Data Release 2 imaging area. Follow-up
spectroscopy using the Hobby-Eberly Telescope, the MMT, and the McDonald 2.7m
Telescope is used to demonstrate that the white dwarf and subdwarf loci
separate cleanly in the reduced proper motion diagram, and that the
contamination by subdwarfs is small near the cool white dwarf locus. This
enables large statistically complete samples of white dwarfs, particularly the
poorly understood cool white dwarfs, to be created from the SDSS imaging
survey, with important implications for white dwarf luminosity function
studies. SDSS photometry for our sample of cool white dwarfs is compared to
current white dwarf models.


title: On the nature of the radio quiet X-ray neutron star 1E 1207.4-5209

abstract:
  The strange timing property of X-ray pulsar 1E 1207.4-5209 can be explained
by the hypothesis that it is a member of an ultra-compact binary system. This
paper confronts the ultra-compact assumption with the observed properties of
this pulsar. The gravitational potential well of an ultra-compact binary can
enlarge the corotation radius and thus make it possible for accreting material
to reach the surface of the NS in the low accretion rate case. Thus the
generation of the absorption features should be similar to the case of
accreting pulsars. The close equality of the energy loss by fast cooling of the
postsupernova neutron star and the energy dissipation needed for a wide binary
evolving to an ultra-compact binary demonstrates that the ultra-compact binary
may be formed in 10-100yr after the second supernova explosion. Moreover, the
ultra-compact binary hypothesis can well explain the the absence of optical
counterpart and the observed two black body emissions. We suggest a simple
method which can test the binary nature directly with XMM-Newton and Chandra
observations. We further predict that the temperature of the two black bodies
should vary at different pulse periods.


title: Power Spectrum Estimation I. Basics

abstract:
  This paper and its companion form an extended version of notes provided to
participants in the Valencia September 2004 summer school on Data Analysis in
Cosmology. The papers offer a pedagogical introduction to the problem of
estimating the power spectrum from galaxy surveys. The intention is to focus on
concepts rather than on technical detail, but enough mathematics is provided to
point the student in the right direction.
  This first paper presents background material. It collects some essential
definitions, discusses traditional methods for measuring power, notably the
Feldman-Kaiser-Peacock (1994) method, and introduces Bayesian analysis, Fisher
matrices, and maximum likelihood. For pedagogy and brevity, several derivations
are set as exercises for the reader. At the summer school, multiple choice
questions, included herein, were used to convey some didactic ideas, and
provoked a little lively debate.


title: Power Spectrum Estimation II. Linear Maximum Likelihood

abstract:
  This second paper of two companion papers on the estimation of power spectra
specializes to the topic of estimating galaxy power spectra at large, linear
scales using maximum likelihood methods. As in the first paper, the aims are
pedagogical, and the emphasis is on concepts rather than technical detail. The
paper covers most of the salient issues, including selection functions,
likelihood functions, Karhunen-Loeve compression, pair-integral bias, Local
Group flow, angular or radial systematics (arising for example from
extinction), redshift distortions, quadratic compression, decorrelation, and
disentanglement. The procedures are illustrated with results from the IRAS PSCz
survey. Most of the PSCz graphics included in this paper have not been
published elsewhere.


title: LP 349-25: a new tight M8V binary

abstract:
  We present the discovery of a tight M8V binary, with a separation of only 1.2
astronomical units, obtained with the PUEO and NACO adaptive optics systems,
respectively at the CFHT and VLT telescopes. The estimated period of LP 349-25
is approximately 5 years, and this makes it an excellent candidate for a
precise mass measurement.


title: Evidence of a counterrotating core in the Large Magellanic Cloud

abstract:
  Stellar radial velocity in the central region of the Large Magellanic Cloud
(LMC) is used to estimate the radial velocity curve along various position
angles (PA) including the line of nodes (LON). The central part of the radial
velocity profile, along the LON, shows a V-shaped profile - a clear indication
of counterrotation. The counterrotating region and the secondary bar have
similar location and PA. The origin of the counter-rotating core could be
internal(secondary bar) or external(accretion). To explain the observed
velocity profile, we propose the existence of two disks in the inner LMC, with
one counterrotating. This two disk model is found to match the HI velocities as
well. Two disks with different LON and velocity profiles can create regions
which are kinematically and spatially separated. Predicted such locations are
found to match the observed locations where the HI clouds are found to have two
velocities.


title:
Oxygen and neon abundances of planetary nebulae in the elliptical galaxy
  NGC 4697

abstract:
  This paper presents deep spectra of 14 planetary nebulae (PNs) at a variety
of angular distances from the center of the flattened elliptical galaxy NGC
4697. Both near the center and among the most outlying PNs we have found
several examples of very strong [O III] 5007, about 20 times brighter than
Hbeta. This, together with strong [Ne III] lines, implies a lower limit for O
and Ne abundances near solar at the center and also at more than two effective
radii from the center of NGC 4697. Thus we have found, for the first time from
individual stars, direct evidence of the existence of a metal-rich population
in elliptical galaxies, confirming metallicities derived from absorption-line
indices and extending the information to angular distances where the stellar
surface brightness is too low for absorption-line studies. A comparison with
abundances obtained closer to the center of NGC 4697 from integrated
absorption-line spectra indicates that the metallicity gradient, which is quite
steep within one effective radius, becomes much less pronounced beyond one
effective radius. The only alternative to this interpretation would be the
presence of a very metal-poor PN population with [Z/H] below -1, which we
cannot rule out but would require an extremely bimodal metallicity distribution
with almost no intermediate metallicities.


title: Comment on the Origin of the Supermassive Black Hole

abstract:
  We give the comment why the supermassive black hole exists at the center of
almost all galaxies. We consider the origin of the supermassive black hole from
the point of view of the density of the matter. If the density of the matter is
fixed and such matter can come together by the gravitational attraction, such
stellar object eventually becomes the black hole. If the density of the matter
is that of the atom, such matter naturally comes together to form the black
hole by the gravitational attraction. This is expected to be the process to
form the supermassive black hole. In this way, we can understand that there
exists supermassive black hole at the center of almost all galaxies, because
there is no delicate process to evolve into the black hole.