Astrophysics

astro-ph new abstracts, Mon, 28 Aug 00 04:00:10 GMT
0008392 — 0008410 received

astro-ph/0008392 [abs, src, ps, other] :

Title: The Real Space Power Spectrum of the PSCz Survey from 0.01 to 300 h/Mpc

Authors:
Andrew J. S. Hamilton (JILA),
Max Tegmark (U. Penn)

Comments: 21 pages including 12 embedded PostScript figures. Submitted to
MNRAS. Data available at this http URL

We report a measurement of the real space (not redshift space) power spectrum
of galaxies over four and a half decades of wavenumber, 0.01 to 300 h/Mpc, from
the IRAS Point Source Catalog Redshift Survey (PSCz). Since estimates of power
are highly correlated in the nonlinear regime, we also report results for the
prewhitened power spectrum, which is less correlated. The inferred bias between
optically-selected APM and IRAS-selected PSCz galaxies is about 1.15 at linear
scales < 0.3 h/Mpc, increasing to about 1.4 at nonlinear scales > 1 h/Mpc. The
nonlinear power spectrum of PSCz shows a near power-law behaviour to the
smallest scales measured, with mild upward curvature in the broad vicinity of
1.5 h/Mpc. Contrary to the prediction of unbiased Dark Matter models, there is
no prominent inflection at the linear-nonlinear transition scale, and no
turnover at the transition to the stable clustering regime. The nonlinear power
spectrum of PSCz requires scale-dependent bias: all Dark Matter models without
scale-dependent bias are ruled out with high confidence.
(287kb)

astro-ph/0008393 [abs, src, ps, other] :

Title: A Monte Carlo Study of the 6.4 keV Emission at the Galactic Center

Authors:
M. J. Fromerth (U. of Arizona),
F. Melia (U. of Arizona)

Comments: 11 pages, 4 EPS figures, uses epsfig.sty, amssym.sty, psfig.sty

Strong fluorescent Fe line emission at 6.4 keV has been observed from the
Sgr~B2 giant molecular cloud located in the Galactic Center region. The large
equivalent width of this line and the lack of an apparent illuminating nearby
object indicate that a time-dependent source, currently in a low-activity
state, is causing the fluorescent emission. It has been suggested that this
illuminator is the massive black hole candidate, Sgr A*, whose X-ray luminosity
has declined by an unprecedented six orders of magnitude over the past 300
years. We here report the results of our Monte Carlo simulations for producing
this line under a variety of source configurations and characteristics. These
indicate that the source may in fact be embedded within Sgr~B2, although
external sources give a slightly better fit to the data. The weakened
distinction between the internal and external illuminators is due in part to
the instrument response function, which accounts for an enhanced equivalent
width of the line by folding some of the continuum radiation in with the
intrinsic line intensity. We also point out that although the spectrum may be
largely produced by K$alpha$ emission in cold gas, there is some evidence in
the data to suggest the presence of warm (~10^5 K) emitting material near the
cold cloud.
(17kb)

astro-ph/0008394 [abs, src, ps, other] :

Title: Quasar-galaxy associations revisited

Authors:
N. Benitez (1),
J. L. Sanz (2),
E. Martinez-Gonzalez (2); ((1) Johns Hopkins University, (2) IFCA)

Comments: 9 pages, 6 figures, MNRAS accepted

Gravitational lensing predicts an enhancement of the density of bright,
distant QSOs around foreground galaxies. We measure this QSO-galaxy correlation
w_qg for two complete samples of radio-loud quasars, the southern 1Jy and
Half-Jansky samples. The existence of a positive correlation between z~1
quasars and z~0.15 galaxies is confirmed at a p=99.0% significance level
(>99.9%) if previous measurements on the northern hemisphere are included). A
comparison with the results obtained for incomplete quasar catalogs (e.g. the
Veron-Cetty and Veron compilation) suggests the existence of an `identification
bias’, which spuriously increases the estimated amplitude of the quasar-galaxy
correlation for incomplete samples. This effect may explain many of the
surprisingly strong quasar-galaxy associations found in the literature.
Nevertheless, the value of w_qg that we measure in our complete catalogs is
still considerably higher than the predictions from weak lensing. We consider
two effects which could help to explain this discrepancy: galactic dust
extinction and strong lensing.
(63kb)

astro-ph/0008395 [abs, src, ps, other] :

Title: Stellar Populations, Bars and Secular Evolution in Late-Type Galaxies

Authors:
D. A. Gadotti (1),
S. dos Anjos (1 and 2) ((1) Departamento de Astronomia / Universidade de Sao Paulo – Brasil, (2) Steward Observatory / University of Arizona – USA)

Comments: 2 pages, 1 table, no figures. To appear in ASP Conference Series,
“Galaxy Disks and Disk Galaxies”, J. G. Funes S. J. and E. M. Corsini, eds

We have done a robust statistical analysis of UBV color profiles of 257 Sbc
barred and unbarred galaxies. We found that there is an excess of barred
galaxies among the objects with null or positive (bluish inward) color
gradients, which seems to indicate that bars act as a mechanism of
homogenization of the stellar population along galaxies. Moreover, the
relationship found between total and bulge colors shows that, in the process of
homogenization, the stellar population of bulges are getting bluer, whereas the
total color of galaxies remains the same. These characteristics are expected in
a secular evolutionary scenario, and seem incompatible with both the monolithic
and the hierarchical scenarios for spiral galaxy formation.
(6kb)

astro-ph/0008396 [abs, src, ps, other] :

Title: Composite Spectra from the FIRST Bright Quasar Survey

Authors:
M. S. Brotherton,
Hien D. Tran,
R. H. Becker,
Michael D. Gregg,
S. A. Laurent-Muehleisen,
R. L. White

Comments: To appear in ApJ. 15 pages, 8 figures

We present a very high signal-to-noise ratio composite spectrum created using
657 radio-selected quasars from the FIRST Bright Quasar Survey. The spectrum
spans rest-frame wavelengths 900 – 7500 Angstroms. Additionally we present
composite spectra formed from subsets of the total data set in order to
investigate the spectral dependence on radio loudness and the presence of broad
absorption. In particular, radio-loud quasars are red compared to radio-quiet
quasars, and quasars showing low-ionization broad absorption lines are red
compared to other quasars. We compare our composites with those from the Large
Bright Quasar Survey. Composite quasar spectra have proven to be valuable tools
for a host of applications, and in that spirit we make these publically
available via the FIRST survey web page.
(337kb)

astro-ph/0008397 [abs, src, ps, other] :

Title: Some Consequences of Magnetic Fields in High Energy Sources

Authors:
Eric G. Blackman (University of Rochester)

Comments: 12 pages, Latex, to Appear in ” Proceedings of The First KIAS
Astrophysics Workshop, “Explosive Phenomena in Astrophysical Compact
Objects”, 2000, edited by H.-Y. Chang, C.-H. Lee, M. Rho, I. Yi, (AIP: New
York)

Magnetic fields likely play a fundamental intermediary role between gravity
and radiation in many astrophysical rotators. They can, among other things, 1)
induce and be amplified by turbulence, 2) energize coronae, 3) launch and
collimate outflows in “spring” or “fling” mechanisms. The first is widely
recognized to be important for angular momentum transport, but can also produce
intrinsic variability and possibly vorticity growth. The second leads to the
production of high energy flares, and also facilitates a test of general
relativity from AGN observations. The third can operate from rotators with a
large scale fields, though the origin of the requisite large scale fields is
somewhat unresolved. I discuss these three points in more detail below,
emphasizing some open questions.
(16kb)

astro-ph/0008398 [abs, src, ps, other] :

Title: A new era of spectroscopy: SINFONI, NIR integral field spectroscopy at
the diffraction limit of an 8m telescope

Authors:
S. Mengel,
F. Eisenhauer,
M. Tecza,
N. Thatte,
C. Roehrle,
K. Bickert,
J. Schreiber

Comments: 9 pages, 4 figures, to appear in SPIE proceedings “Astronomical
Telescopes and Instrumentation 2000”. More recent sensitivity estimates are
available at this http URL

SINFONI, the SINgle Faint Object Near-infrared Investigation, is an
instrument for the Very Large Telescope (VLT), which will start its operation
mid 2002 and allow for the first time near infrared (NIR) integral field
spectroscopy at the diffraction limit of an 8-m telescope. SINFONI is the
combination of two state-of-the art instruments, the integral field
spectrometer SPIFFI, built by the Max-Planck-Institut fuer extraterrestrische
Physik (MPE), and the adaptive optics (AO) system MACAO, built by the European
Southern Observatory (ESO). It will allow a unique type of observations by
delivering simultaneously high spatial resolution (pixel sizes 0.025arcsec to
0.25arcsec) and a moderate spectral resolution (R~2000 to R~4500), where the
higher spectral resolution mode will allow for software OH suppression. This
opens new prospects for astronomy.
(63kb)

astro-ph/0008399 [abs, src, ps, other] :

Title: Thermodynamical properties of stellar matter: II. Internal energy,
temperature and density exponents and specific heats for stellar interiors

Authors:
W. Stolzmann (1,2),
T. Bloecker (3) ((1) Institut fuer Theoretische Physik und Astrophysik, Universitaet Kiel, Germany – (2) Astrophysikalisches Institut Potsdam, Germany – (3) Max-Planck-Institut fuer Radioastronomie, Bonn, Germany)

Comments: 17 pages including 20 PostScript figures; also available from
this http URL; Astronomy &
Astrophysics, in press

Starting from the Helmholtz free energy we calculate analytically first- and
second-order derivatives, as internal energy and specific heats, for the ideal
system and the exchange and correlation interactions covering a broad range of
degeneracy and relativity. The complex physics of Coulomb interactions is
expressed by Pade Approximants, which reflect the actual state of our knowledge
with high accuracy. We assume complete ionization and provide a base system of
thermodynamical functions from which any other thermodynamical quantities can
be calculated. We chose for the base system the free energy, the pressure, the
internal energy, the isothermal compressibility (or density exponent), the
coefficient of strain (or temperature exponent), and the isochoric specific
heat. By means of the latter potentials entropy, isobaric specific heat and
adiabatic temperature gradient can be determined. We give comparisons with
quantities which are composed by numerical second-order derivatives of the free
energy and show that numerical derivatives of the free energy as calculated,
for instance, from EOS tables, may produce discontinuities for astrophysically
relevant quantities as, e.g., the adiabatic temperature gradient. Adiabatic
temperature gradients are shown for different chemical compositions (hydrogen,
helium, carbon). Finally the used formalism of Pade Approximants allows
immediate incorporation of recent results from many particle statistics.
(332kb)

astro-ph/0008400 [abs, src, ps, other] :

Title: S 10947 Aql = RX J2009.8+1557: A probable RS CVn star which sometimes
stops its eclipses

Authors:
G.A. Richter (Sonneberg, Germany),
J. Greiner (Astrophys. Inst. Potsdam, Germany)

Comments: 5 pages, LATEX with aa.sty, 4 ps-figs., A&A (accepted), also
available at this http URL

We report the discovery of a new variable star, called S 10947 Aql, as the
likely optical counterpart of RX J2009.8+1557. The optical variability pattern
as well as the detected X-ray emission suggest that it is a chromospherically
active binary of the RS Canum Venaticorum type. We discovered an occasional
disappearance of the eclipsing minima as well as large variations in the
eclipse amplitude. We discuss possible causes of this peculiarity.
(76kb)

astro-ph/0008401 [abs, src, ps, other] :

Title: Discovery of a Close Pair of z = 4.25 Quasars from the Sloan Digital Sky
Survey

Authors:
Donald P. Schneider,
Xiaohui Fan,
Michael A. Strauss,
James E. Gunn,
Gordon T. Richards,
G. R. Knapp,
Robert H. Lupton,
David H. Saxe,
John E. Anderson Jr.,
Neta A. Bahcall,
J. Brinkmann,
Robert Brunner,
Istvan Csabái,
Masataka Fukugita,
G. S. Hennessy,
Robert B. Hindsley,
Zeljko Ivezic,
R. C. Nichol,
Jeffrey R. Pier,
Donald G. York

Comments: 15 pages, 4 figures, submitted to AJ

We report the discovery of a pair of z = 4.25 quasars with a separation of 33
arcseconds. The brighter of the two objects was identified as a high-redshift
quasar candidate from Sloan Digital Sky Survey multicolor imaging data, and the
redshift was measured from a spectrum obtained with the Hobby-Eberly Telescope.
The slit orientation of this observation {it by chance} included another
quasar, approximately one magnitude fainter and having the same redshift as the
target. This is the third serendipitous discovery of a z > 4 quasar. The
differences in the relative strengths and profiles of the emission lines
suggest that this is a quasar pair and not a gravitational lens. The two
objects are likely to be physically associated; the projected physical
separation is approximately 210 $h_{50}^{-1}$ kpc and the redshifts are
identical to $approx$ 0.01, implying a radial physical separation of 950
$h_{50}^{-1}$ kpc or less. The existence of this pair is strong circumstantial
evidence that $z sim 4$ quasars are clustered.
(268kb)

astro-ph/0008402 [abs, src, ps, other] :

Title: First UVES observations of beryllium in very metal-poor stars

Authors:
Francesca Primas (1),
Paolo Molaro (2),
Piercarlo Bonifacio (2),
Vanessa Hill (1) ((1) European Southern Obs., Germany; (2) Oss. Astronomico di Trieste, Italy)

Comments: accepted for publication in A&A Main Journal

We report on a attempt to detect beryllium in two dwarf stars of the Galactic
halo with metallicities below one thousandth solar. The data were obtained
during the Commissioning of the Ultraviolet and Visible Echelle Spectrograph
(UVES) mounted on the ESO VLT Kueyen telescope, and show the potential of UVES
for studies in the UV-optical domain. We claim a beryllium detection in LP
815–43 ([Fe/H]~-2.95,[Be/H]=-13.09) at the 99.7% confidence level, while only
an upper limit can be set for the second target CD -24 17504 ([Fe/H]~-3.30,
[Be/H]~-13.39). These results suggest that the trend of beryllium with
metallicity keeps decreasing as lower metallicities are probed, with no
evidence for flattening. In CD -24 17504 we also analyzed the Li I line at
6708A, and derived a lithium abundance close to the Spite plateau.
(35kb)

astro-ph/0008403 [abs, src, ps, other] :

Title: The Effects of Dust on the Spectral Energy Distributions of Star-Forming
Galaxies

Authors:
Daniela Calzetti (Space Telescope Science Institute)

Comments: Invited Review at the FIRSED2000 Workshop on The Far-Infrared and
Submillimiter Spectral Energy Distributions of Active and Starburst Galaxies,
edited by P. Barthel, B. Wilkes and I. van Bemmel, New Astronomy Reviews
(Elsevier, The Netherlands). 11 Latex pages plus 5 encapsulated postscript
figures. Uses the elsart.cls and natbib.sty style files

I review the effects of dust, both in absorption and in emission, on the
spectral energy distributions (SEDs) of Local star-forming galaxies. The energy
balance between the stellar light absorbed by dust at UV-optical-nearIR
wavelengths and the energy re-emitted by dust in the far infrared (FIR) shows
that the amount of dust extinction affecting the galaxy can be predicted with
simple prescriptions applied to the UV-optical data. The implications of these
results for high redshift galaxies are discussed. Arguments can be given to
support the view that Local starbursts are representative of high-redshift
(z>2), UV-detected, star-forming galaxies. If this is the case, the high
redshift FIR emission will be generally undetected in sub-mm surveys, unless
(1) the bolometric luminosity of the high-z galaxies is comparable to or larger
than that of Local ultraluminous FIR galaxies and (2) their FIR SED contains a
cool dust component.
(65kb)

astro-ph/0008404 [abs, src, ps, other] :

Title: Broad-Band Spectral Energy Distributions of Active Galactic Nuclei from
an Accretion Disk with Advective Coronal Flow

Authors:
Toshihiro Kawaguchi (1),
Toshiya Shimura (2),
Shin Mineshige (1) ((1) Department of Astronomy, Kyoto University (2) Yokohama National University)

Comments: 12 pages, 9 figures, accepted for publication in the Astrophysical
Journal

We construct a disk-corona model which accounts for the optical-to-X-ray
spectral properties of Seyfert nuclei and QSOs. We study emission spectrum
emerging from a vertical disk-corona structure composed of two-temperature
plasma by solving hydrostatic equilibrium and radiative transfer
self-consistently. A fraction $f$ of viscous heating is assumed to be
dissipated in a corona with a Thomson optical depth of $ au_c$, where
advective cooling is also included, and a remaining fraction, $1-f$, dissipates
within a main body of the disk. Our model can nicely reproduce the soft X-ray
excess with a power-law shape and the hard tail extending to $sim$ 50 keV. The
different spectral slopes ($alpha sim$ 1.5 below 2keV and $sim$ 0.5 above,
where $Fnu propto
u^{- alpha}$) are the results of different emission
mechanisms and different sites; the former slope is due to unsaturated
Comptonization from the innermost zone and the latter is due to a combination
of the Comptonization, bremsstrahlung and a reflection of the coronal radiation
at the disk-corona boundary from the inner to surrounding zone ($leq$ 300
Schwarzschild radii). The emergent optical spectrum is redder ($alpha sim
0.3$) than that of the standard disk ($alpha sim -0.3$), being consistent
with observations, due to the different efficiencies of spectral distortion of
disk emission at different radii. Further, we find that the cut-off frequency
of the hard X-ray ($sim$ coronal electron temperature) and broad-band spectral
shape are insensitive to the black-hole mass, while the peak frequency of the
big blue bump is sensitive to the mass as the peak frequency $propto
Mbh^{-1/4}$.
(136kb)

astro-ph/0008405 [abs, pdf] :

Title: A Search for Point Sources of Cosmic Primary Rays Which Produce Single
Muon Tracks at Ground Level

Authors:
A. Roesch,
J. Carpenter,
S. Desch,
J. Gress,
T.F. Lin,
J. Poirier

Comments: 4 pgs; includes 1 fig. and 2 tables. HE.3.2.10 in 26th ICRC, 2, 104,
(1999)

An increased data sample of identified secondary muons is collected at
detection level. Project GRAND identifies secondary cosmic ray muons from
electrons utilizing a thin steel absorber and tracking (PWC) chambers. The
resulting angular resolution for the primary is about +/- 5 degrees. Since
there is a 1.5% probability that a 100 GeV gamma primary will produce a single
muon track at ground level, the high statistics allows a search for angular
enhancements due to gammas. More than 100 billion muons are identified and
analyzed. A table of stellar sources is examined.
(490kb)

astro-ph/0008406 [abs, src, ps, other] :

Title: A Near-Infrared Photometric Survey of Metal-Poor Inner Spheroid Globular
Clusters and Nearby Bulge Fields

Authors:
T. J. Davidge

Comments: 40 pages of text; 25 postscript figures; to appear in the
Astronomical Journal

Images recorded through J, H, K, 2.2 micron continuum and CO filters have
been obtained of a sample of metal-poor ([Fe/H] < -1.3) globular clusters in
the inner spheroid of the Galaxy. The shape and color of the upper giant branch
on the (K, J-K) CMD, combined with the K brightness of the RGB-tip, are used to
estimate the metallicity, reddening, and distance of each cluster. CO indices
are used to identify bulge stars, which will bias metallicity and distance
estimates if not removed from the data. Bulge fields were also observed near
each cluster. The slope of the bulge giant branch luminosity function does not
vary between most fields, although the LFs in Baade’s Window and near NGC 6273
are significantly shallower than average. The data also suggest that the HB
content may not be uniform throughout the bulge, in the sense that a larger
than average number of red HB stars may occur in fields closest to the Galactic
Center.
(192kb)

astro-ph/0008407 [abs, pdf] :

Title: Corrections to the Predicitions for Atmospheric Neutrino Observations

Authors:
J. Poirier

Comments: 4 pages. HE.3.2.26 in 26th ICRC, 2, 147 (1999)

The theoretical Monte Carlo calculations of the production of neutrinos via
cosmic rays incident upon the earth’s atmosphere are examined. The calculations
are sensitive to the assumed ratio of pi+ / pi- production cross sections; this
ratio appears to be underestimated in the theory relative to the experimentally
measured ratio. Since the neutrino detection cross section is three times
larger than that for the antineutrino, the theoretical predicted detection
ratio (nu_mu / nu_e) is correspondingly too large.
(100kb)

astro-ph/0008408 [abs, src, ps, other] :

Title: Oxygen Absorption in M87: Evidence for a Warm+Hot ISM

Authors:
David A. Buote (UC Santa Cruz)

Comments: 17 pages (13 figures), Accepted for Publication in The Astrophysical
Journal

We present a re-analysis of the ROSAT PSPC data within the central 100 kpc of
M87 to search for intrinsic oxygen absorption similar to that recently measured
in several galaxies and groups. Using a spatial-spectral deprojection analysis
we find the strongest evidence to date for intrinsic oxygen absorption in the
hot gas of a galaxy, group, or cluster. Single-phase plasma models modified by
intervening Galactic absorption cannot fit the 0.2-2.2 keV PSPC data as they
under-predict the 0.2-0.4 keV region and over-predict the 0.5-0.8 keV region
where the emission and absorption residuals are obvious upon visual inspection
of the spectral fits. Since the excess emission between 0.2-0.4 keV rules out
intrinsic absorption from cold gas or dust, the most reasonable model for the
excess emission and absorption features is warm, collisionally ionized gas with
a temperature of ~10^6 K. Simple multiphase models (cooling flow, two phases)
modified by both intervening Galactic absorption and by a single oxygen edge
provide good fits and yield temperatures and Fe abundances of the hot gas that
agree with previous determinations by ASCA and SAX. The multiphase models of
M87 inferred from the PSPC can account for the excess EUV emission observed
with EUVE and the excess X-ray absorption inferred from EINSTEIN and ASCA data
above 0.5 keV. Although the total mass of the warm gas implied by the oxygen
absorption is consistent with the matter deposited by a cooling flow, the
suppression of the mass deposition rate and the distortion of the X-ray
isophotes in the region where the radio emission is most pronounced suggest
some feedback effect from the AGN on the cooling gas. (Abridged)
(178kb)

astro-ph/0008409 [abs, pdf] :

Title: The South Atlantic Magnetic Field Anomaly and Its Effect on the
Calculated Production of Atmospheric Neutrinos

Authors:
J. Poirier

Comments: 4 pages. 26th ICRC, vol 2, 253 (1999)

The theoretical calculations of the production of neutrinos via cosmic rays
incident upon the earth’s atmosphere (Barr et al., 1989; Becker-Szendy et al.,
1992; Bugaev & Naumov, 1989; Gaisser et al, 1988; Honda et al., 1995) are
examined. These calculations use a one-dimensional approximation in the
production, transport, and decay of the produced particles. Examined are
various additional effects of the earth’s magnetic field and the
three-dimensional nature of the problem which have the effect of decreasing the
calulated ratio of muon neutrinos to electron neutrinos.
(108kb)

astro-ph/0008410 [abs, src, ps, other] :

Title: The X-ray Spectrum and Light Curve of Supernova 1995N

Authors:
D. W. Fox (1),
W. H. G. Lewin (1),
A. Fabian (2),
K. Iwasawa (2),
R. Terlevich (3),
H. U. Zimmermann (4),
B. Aschenbach (4),
K. Weiler (5),
S. Van Dyk (6),
R. Chevalier (7),
R. Rutledge (8),
H. Inoue (9),
S. Uno (9) ((1) MIT, (2) IoA Cambridge, (3) Royal Greenwich Observatory, (4) MPE, (5) NRL, (6) IPAC, (7) UVA, (8) Caltech, (9) ISAS)

Comments: MNRAS accepted. 6 pages, 2 figures; uses mn.sty and psfig

We report on multi-epoch X-ray observations of the Type IIn (narrow emission
line) supernova SN 1995N with the ROSAT and ASCA satellites. The January 1998
ASCA X-ray spectrum is well fitted by a thermal bremsstrahlung (kT~10 keV,
N_H~6e20 cm^-2) or power-law (alpha~1.7, N_H~1e21 cm^-2) model. The X-ray light
curve shows evidence for significant flux evolution between August 1996 and
January 1998: the count rate from the source decreased by 30% between our
August 1996 and August 1997 ROSAT observations, and the X-ray luminosity most
likely increased by a factor of ~2 between our August 1997 ROSAT and January
1998 ASCA observations, although evolution of the spectral shape over this
interval is not ruled out. The high X-ray luminosity, L_X~1e41 erg/sec, places
SN 1995N in a small group of Type IIn supernovae with strong circumstellar
interaction, and the evolving X-ray luminosity suggests that the circumstellar
medium is distributed inhomogeneously.
(119kb)

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Cross-listings

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cond-mat/0008371 [abs, src, ps, other] :

Title: Superfluid Hydrodynamics of an Electron Gas in a Superstrong Magnetic
Field

Authors:
Eugene B. Kolomeisky

Comments: 4 paqes, 3 figures

We derive the equations of hydrodynamics of a fully polarized electron gas
placed in a strong magnetic field. These equations reveal the existence of
solitons – immobile or propagating domain wall-like defects whose plane is
perpendicular to the field direction. The solitons are used to construct weakly
excited states, and novel nonuniform persistent current states of the system.
(17kb)

gr-qc/0008058 [abs, src, ps, other] :

Title: Gravitational waves from extreme mass ratio inspirals: Challenges in
mapping the spacetime of massive, compact objects

Authors:
Scott A. Hughes

Comments: 6 pages, 2 figures. To appear (modulo refereeing) in the Proceedings
of the 3rd International LISA Symposium

In its final year of inspiral, a stellar mass ($1 – 10 M_odot$) body orbits
a massive ($10^5 – 10^7 M_odot$) compact object about $10^5$ times, spiralling
from several Schwarzschild radii to the last stable orbit. These orbits are
deep in the massive object’s strong field, so the gravitational waves that they
produce probe the strong field nature of the object’s spacetime. Measuring
these waves can, in principle, be used to “map” this spacetime, allowing
observers to test whether the object is a black hole or something more exotic.
Such measurements will require a good theoretical understanding of wave
generation during inspiral. In this article, I discuss the major theoretical
challenges standing in the way of building such maps from gravitational-wave
observations, as well as recent progress in producing extreme mass ratio
inspirals and waveforms.
(38kb)

hep-ph/0008258 [abs, src, ps, other] :

Title: Active-Sterile neutrino oscillations and BBN+CMBR constraints

Authors:
P. Di Bari,
R. Foot

Comments: Latex, about 15 pages with 2 figs

We show how active-sterile neutrino oscillations in the early Universe can
play an interesting role in explaining the current observations of CMBR
anisotropies and light element abundances. We describe different possible
phenomenological scenarios in the interpretation of present data and how
active-sterile neutrino oscillations can provide a viable theoretical
framework.
(43kb)

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Replacements

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astro-ph/9910488 [abs, src, ps, other] :

Title: The Dependence of Velocity and Clustering Statistics on Galaxy
Properties

Authors:
A. J. Benson,
C. M. Baugh,
S. Cole,
C. S. Frenk,
C. G. Lacey

Comments: 14 pages, 14 figures, to appear in MNRAS, discussion of number of
galaxies per halo added – conclusions unchanged

Journal-ref: MNRAS, 316, 107

Note: replaced with revised version Fri, 25 Aug 2000 12:21:06 GMT (161kb)

astro-ph/9912220 [abs, src, ps, other] :

Title: A Comparison of Semi-Analytic and Smoothed Particle Hydrodynamics Galaxy
Formation

Authors:
A. J. Benson,
F. R. Pearce,
C. S. Frenk,
C. M. Baugh,
A. Jenkins (University of Durham, UK)

Comments: 19 pages, 13 figures, to appear in MNRAS. Significantly extended to
explore galaxy progenitor distributions and behaviour of models at high
redshifts

Note: replaced with revised version Fri, 25 Aug 2000 12:36:58 GMT (202kb)

astro-ph/0002457 [abs, src, ps, other] :

Title: Non-uniform reionization by galaxies and its effect on the cosmic
microwave backgroun

Authors:
A. J. Benson (1),
Adi Nusser (2),
Naoshi Sugiyama (3),
C. G. Lacey (4) ((1) University of Durham, UK, (2) Technion, Israel, (3) Kyoto University, Japan, (4) SISSA, Italy)

Comments: 26 pages, 19 figures, to appear in MNRAS – improved calculation of
clumping factors included plus comparison with local ionizing background
intensity – small changes in reionization redshift as a result

Note: replaced with revised version Fri, 25 Aug 2000 12:30:10 GMT (637kb)

astro-ph/0006222 [abs, src, ps, other] :

Title: Removing radio interference from contaminated astronomical spectra using
an independent reference signal and closure relations

Authors:
F. H. Briggs,
J. F. Bell,
M. J. Kesteven

Comments: 15 pages, 13 figures, accepted at AJ

Note: replaced with revised version Fri, 25 Aug 2000 15:39:58 GMT (278kb)

astro-ph/0008165 [abs, src, ps, other] :

Title: Global fits for the spectral index of the cosmological curvature
perturbation

Authors:
Laura Covi,
David H. Lyth

Comments: More details of the fit, comparison with other fits, and discussion
of approaches to comparison with theory

Note: replaced with revised version Fri, 25 Aug 2000 17:22:35 GMT (61kb)

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Report-no: EFI-2000-26

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