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astro-ph/9512075
SPH Calculations of Collisions between Main-Sequence Stars
The hydrodynamics of collisions and mergers of main-sequence stars is discussed in the light of recent 3-D calculations using the smoothed particle hydrodynamics (SPH) method. Theoretical models for the formation of blue stragglers are reviewed in the context of recent comparisons between the observed properties of blu...
1995-12-12
2007-05-23
[ "astro-ph" ]
Frederic A. Rasio (MIT)
astro-ph/9512073
The first simultaneous X-ray/gamma-ray observations of Cyg X-1 by Ginga and OSSE
We present the results of 4 simultaneous observations of Cygnus X-1 by Ginga and OSSE. The X-ray/gamma-ray spectra can be described by an intrinsic continuum and a component due to Compton reflection including an iron K-alpha line. The intrinsic spectrum at X-ray energies is a power-law with a photon spectral index of ...
1995-12-12
2007-05-23
[ "astro-ph" ]
Marek Gierlinski (1), Andrzej A. Zdziarski (2), W. Neil Johnson (3), Bernard F. Phlips (3), Ken Ebisawa (4), and Chris Done (5) ((1) Astr. Obs. UJ, Cracow, Poland, (2) Copernicus Astr. Center, Warsaw, Poland, (3) E. O. Hulburt Center for Space Res., Naval Research Lab, Washington DC, U.S.A., (4) NASA/GSFC, Gree...
astro-ph/9512079
The Search for Neutrino Sources Beyond the Sun
The hope is that in the near future neutrino astronomy, born with the identification of thermonuclear fusion in the sun and the particle processes controlling the fate of a nearby supernova, will reach throughout and beyond our Galaxy and make measurements relevant to cosmology, astrophysics, cosmic-ray and particle ph...
1995-12-12
2009-10-28
[ "astro-ph", "hep-ph" ]
S. Barwick, F. Halzen, and P.B. Price
astro-ph/9512080
Ultra-Transparent Antarctic Ice as a Supernova Detector
We have simulated the response of a high energy neutrino telescope in deep Antarctic ice to the stream of low energy neutrinos produced by a supernova. The passage of a large flux of MeV-energy neutrinos during a period of seconds will be detected as an excess of single counting rates in all individual optical modules....
1995-12-12
2014-10-13
[ "astro-ph", "hep-ph" ]
F. Halzen, J.E. Jacobsen, and E. Zas
astro-ph/9512068
Future Possibilities for Observing HI at High Redshift
We briefly review the beginnings of HI astronomy, proceed to an assessment of our current capabilities in this area, and continue by considering what will be necessary to push back the frontier to cosmological distances. We then consider how such a leap in performance might be realized.
1995-12-12
2016-01-27
[ "astro-ph" ]
Robert Braun (NFRA)
astro-ph/9512074
Two Classes of Gamma-Ray Bursts
Data from the 3B Catalogue suggest that short and long GRB are the results of different classes of events, rather than different parameter values within a single class: Short bursts have harder spectra in the BATSE bands, but chiefly long bursts are detected at photon energies over 1 MeV, implying that their hard photo...
1995-12-12
2007-05-23
[ "astro-ph" ]
J. I. Katz and L. M. Canel
astro-ph/9512071
The Zel'dovich-type approximation for an inhomogeneous universe in general relativity: second-order solutions
The gravitational instability of inhomogeneities in the expanding universe is studied by the relativistic second-order approximation. Using the tetrad formalism we consider irrotational dust universes and get equations very similar to those given in the Lagrangian perturbation theory in Newtonian cosmology. Neglecting ...
1995-12-12
2009-10-28
[ "astro-ph", "gr-qc" ]
H. Russ, M. Morita, M. Kasai and G. Boerner
astro-ph/9512078
Adaptive Smoothed Particle Hydrodynamics: Methodology II
This paper presents an alternative formulation of the ASPH algorithm for evolving anisotropic smoothing kernels, in which the geometric approach of Shapiro et al. (1996; Paper I) is replaced by an approach involving a local transformation of coordinates to those in which the underlying anisotropic volume changes appear...
1995-12-12
2015-06-24
[ "astro-ph" ]
J. Michael Owen, Jens V. Villumsen, Paul R. Shapiro, Hugo Martel
astro-ph/9512077
The Radio Galaxy 3C265 Contains a Hidden Quasar Nucleus
We report the discovery of broad MgII emission from the high redshift radio galaxy 3C265 (z=0.81). We detect the broad line in the nuclear spectrum and in the spatially extended galaxian component, both near the nucleus and in the spectrum of an off-nuclear knot located 31 kpc south east of the nucleus of the galaxy. T...
1995-12-12
2009-10-28
[ "astro-ph" ]
Arjun Dey (NOAO/KPNO) and Hyron Spinrad (UC Berkeley)
astro-ph/9512076
The Post-Merger Elliptical NGC 1700: Stellar Kinematic Fields to Four Effective Radii
We have measured the stellar motions in the elliptical galaxy NGC 1700 along four position angles, to very large radii, using absorption features in spectra obtained with the Multiple Mirror Telescope. Our data extend the coverage of the stellar velocity field by a factor of 5 (2.5 times further in radius and twice as ...
1995-12-12
2009-10-28
[ "astro-ph" ]
Thomas S. Statler (U. of North Carolina, Chapel Hill and Ohio U.), Tammy Smecker-Hane (Dominion Astrophys. Obs. and U. of California at Irvine), and Gerald N. Cecil (U. of North Carolina, Chapel Hill)
astro-ph/9512067
Measurements of Anisotropy in the Cosmic Microwave Background Radiation at 0\fdg5 Scales near the Stars HR5127 and Phi Herculis
We present measurements of cosmic microwave background (CMB) anisotropy near the stars HR5127 and Phi Herculis from the fifth flight of the Millimeter-wave Anisotropy eXperiment (MAX). We scanned 8\arcdeg\ strips of the sky with an approximately Gaussian 0\fdg5 FWHM beam and a 1\fdg4 peak to peak sinusoidal chop. The i...
1995-12-12
2009-10-28
[ "astro-ph" ]
S. T. Tanaka, A. C. Clapp, M. J. Devlin, N. Figueiredo, J. O. Gundersen, S. Hanany, V. V. Hristov, A. E. Lange, M. A. Lim, P. M. Lubin, P. R. Meinhold, P. L. Richards, G. F. Smoot, and J. Staren
astro-ph/9512070
Automated Detection of Voids in Redshift Surveys
We present a new void search algorithm for automated detection of voids in three-dimensional redshift surveys. Based on a model in which the main features of the LSS of the Universe are voids and walls, we classify the galaxies into wall galaxies and field galaxies and we define voids as continuous volumes that are dev...
1995-12-12
2009-10-28
[ "astro-ph" ]
Hagai El-Ad (1), Tsvi Piran (1), Luiz Nicolaci da Costa (2) ((1) Hebrew University, Jerusalem, Israel, (2) ESO)
astro-ph/9512069
A radio Search for high redshift HI absorption
Ground based optical observations have yielded considerable information on the statistics of damped-lyman alpha systems. In particular these systems are known to be the dominant repository of the observed neutral gas at high redshift. However, particularly at high redshift, there is the possibility that optical observa...
1995-12-12
2016-01-27
[ "astro-ph" ]
Jayaram N. Chengalur, A. G. de Bruyn, R. Braun, C. L. Carilli
astro-ph/9512072
Ultraviolet Imaging and Spectroscopy of LINERs
I review the UV properties of LINERs (low-ionization nuclear emission-line regions), based mostly on the recent {\it HST} UV imaging survey of nearby galaxies by Maoz et al. (1995). 25 of the galaxies in the northern subsample host a LINER nucleus. Six of these display a prominent compact ($<$ few pc) nuclear UV ($\sim...
1995-12-12
2007-05-23
[ "astro-ph" ]
Dan Maoz (Tel-Aviv University)
astro-ph/9512061
Polytropic gas spheres: An approximate analytic solution of the Lane-Emden equation
Polytropic models play a very important role in galactic dynamics and in the theory of stellar structure and evolution. However, in general, the solution of the Lane-Emden equation can not be given analytically but only numerically. In the Lane-Emden equation can not be given analytically but only numerically. In this ...
1995-12-11
2015-06-24
[ "astro-ph" ]
F.K. Liu (International School for Advanced Studies, Trieste, Italy)
astro-ph/9512059
Results from Monitoring the Broad-Line Radio Galaxy 3C 390.3
During 1995, the broad-line radio galaxy 3C 390.3 is the subject of a multi-wavelength monitoring campaign comprised of ROSAT HRI, IUE, and ground based optical, infrared and radio observations. We report preliminary results from the monitoring campaign focusing on the X-ray observations. Snapshot ROSAT observations be...
1995-12-11
2007-05-23
[ "astro-ph" ]
K. M. Leighly (RIKEN), M. Dietrich (Landessternwarte Heidelberg), E. Waltman (NRL), R. Edelson (University of Iowa), I. George (USRA/NASA/GSFC), M. Malkan (University of California), M. Matsuoka (RIKEN), R. Mushotzky (NASA/GSFC), B. M. Peterson (Ohio State University)
astro-ph/9512057
Autofib Redshift Survey - I. Evolution of the Galaxy Luminosity Function
We present a detailed determination of the restframe B-band galaxy luminosity function (LF) as a function of redshift and star formation activity from z=0 to z=0.75. The dataset used for this purpose is a combined sample of over 1700 redshifts spanning a wide range in apparent magnitude, 11.5<B<24.0, which we term the ...
1995-12-11
2015-06-24
[ "astro-ph" ]
Richard S. Ellis, Matthew Colless, Tom Broadhurst, Jeremy Heyl & Karl Glazebrook
astro-ph/9512064
A Self-Consistent Dynamical Model for the COBE Detected Galactic Bar
A 3D steady state stellar dynamical model for the Galactic bar is constructed with 485 orbit building blocks using an extension of Schwarzschild technique. The weights of the orbits are assigned using non-negative least square method. The model fits the density profile of the COBE light distribution, the observed solid...
1995-12-11
2015-06-24
[ "astro-ph" ]
HongSheng Zhao(MPA-Garching)
astro-ph/9512065
A Consistent Microlensing Model for the Galactic Bar
We compute a microlensing map for the Galactic bar. The predicted event rate and event duration distribution are consistent with the $55$ events recently reported by the MACHO and OGLE collaborations. Most of the events are due to lensing by stars in the near end of the bar. Lens mass functions with about 30-60\% of le...
1995-12-11
2015-06-24
[ "astro-ph" ]
HongSheng Zhao(MPA-Garching), R.M. Rich(CU), D.N. Spergel(PU)
astro-ph/9512056
The X-ray spectrum of the Gamma Bright Quasar S5 0836+710
We present the results of an ASCA observation of the high redshift flat spectrum radio quasar S5 0836+710. The $\sim 0.4-10$ keV X-ray spectrum is remarkably flat with $\Gamma \sim 1.4$ and substantial intrinsic absorption at low energy. The spectral slope was found to be in good agreement with the non--simultaneous RO...
1995-12-11
2007-05-23
[ "astro-ph" ]
A. Comastri (Oss. Astr. di Bologna, RIKEN), M. Cappi (RIKEN) and M. Matsuoka (RIKEN)
astro-ph/9512062
On the Spectral Slopes of Hard X-ray Emission from Black Hole Candidates
Most black hole candidates exhibit characteristic power-law like hard X-ray emission above $\sim$ 10 keV. In the {\em high state}, in which 2 -- 10 keV luminosity is relatively high, the energy index of the hard X-ray emission is usually greater than 1 --- typically $\sim 1.5$. On the other hand, in the {\em low state}...
1995-12-11
2015-06-24
[ "astro-ph" ]
Ken Ebisawa, Lev G. Titarchuk and Sandip K. Chakrabarti
astro-ph/9512063
Cluster Cores, Gravitational Lensing, and Cosmology
Many multiply--imaged quasars have been found over the years, but none so far with image separation in excess of $8\arcsec$. The absence of such large splittings has been used as a test of cosmological models: the standard Cold Dark Matter model has been excluded on the basis that it predicts far too many large--separa...
1995-12-11
2009-10-28
[ "astro-ph" ]
Ricardo A. Flores (UM-St. Louis) and Joel R. Primack (UC-Sta. Cruz)
astro-ph/9512066
New Parametrizations of Non-Gaussian Line-of-sight Velocity Distribution
A five-parameter fitting formula for the line-of-sight stellar velocity distributions of steady state systems is proposed. It can faithfully reproduce velocity distributions of theoretical models ranging from nearly Gaussian profiles to strongly skewed or mildly double-peaked profiles. In contrast to van der Marel and ...
1995-12-11
2015-06-24
[ "astro-ph" ]
HongSheng Zhao(MPA-Garching) and Francisco Prada(MPE,IAC)
astro-ph/9512060
The Square Kilometer Array Interferometer
The scientific motivation is reviewed for a next generation radio observatory operating at frequencies between about 200 MHz and 2 GHz with about 2 orders of magnitude greater sensitivity than that which is currently available, together with sub-arcsecond angular resolution. Instrumental concepts for the telescope are ...
1995-12-11
2016-11-03
[ "astro-ph" ]
Robert Braun (NFRA)
astro-ph/9512058
The Environment of ``E+A'' Galaxies
The violent star formation history of ``E+A'' galaxies and their detection almost exclusively in distant clusters is frequently used to link them to the ``Butcher-Oemler effect'' and to argue that cluster environment influences galaxy evolution. From 11113 spectra in the Las Campanas Redshift Survey, we have obtained a...
1995-12-11
2009-05-29
[ "astro-ph" ]
A.I. Zabludoff (OCIW), D. Zaritsky (UCSC/Lick), H. Lin (UToronto), D. Tucker (Potsdam), Y. Hashimoto (Yale), S.A. Shectman (OCIW), A. Oemler (Yale), and R.P. Kirshner (CfA)
astro-ph/9512054
Clumpy Cold Dark Matter and Biological Extinctions
Cosmological models with cosmic string and texture seeded universes predict a present abundance of very dense clumps of Cold Dark Matter particles. Their crossing through the solar system would induce a non-negligible amount of radiation damage to all living tissue; the severity of such an episode is assessed. The esti...
1995-12-10
2009-10-28
[ "astro-ph" ]
J.I.Collar (G.P.S., Univ. Paris 7)
astro-ph/9512055
Reconstructing Positions \& Peculiar Velocities of Galaxy Clusters within 25000 km/sec: The Bulk Velocity
Using a dynamical 3-D reconstruction procedure we estimate the peculiar velocities of $R\ge0$ Abell/ACO galaxy clusters from their measured redshift within 25000 km/sec. The reconstruction algorithm relies on the linear gravitational instability hypothesis, assumes linear biasing and requires an input value of the clus...
1995-12-10
2009-10-28
[ "astro-ph" ]
Enzo Branchini, Manolis Plionis and Dennis W. Sciama
astro-ph/9512053
Advection-Dominated Accretion Flows: Optically Thin Solutions
General properties of advection-dominated accretion flows are discussed. Special emphasis is given to the optically thin branch of solutions, which has very high ion and electron temperatures and is thermally stable. This solution branch has been applied to a number of low-luminosity accreting black holes. The models h...
1995-12-09
2007-05-23
[ "astro-ph" ]
Ramesh Narayan
astro-ph/9512050
The dynamics of planetary nebulae in the Galaxy: evidence for a third integral
We present a dynamical analysis of 673 galactic Planetary Nebulae, using a two-integral axisymmetric model with a Kuzmin-Kutuzov St\"{a}ckel potential. The method fits the kinematics to the projected moments of a distribution function, by means of Quadratic Programming. The 2.2 $\mu$m COBE brightness map has been used ...
1995-12-08
2007-05-23
[ "astro-ph" ]
S. Durand, H. Dejonghe, and A. Acker
astro-ph/9512047
Cosmological Applications of Gravitational Lensing
The last decade has seen an enormous increase of activity in the field of gravitational lensing, mainly driven by improvements of observational capabilities. I will review the basics of gravitational lens theory, just enough to understand the rest of this contribution, and will then concentrate on several of the main a...
1995-12-08
2015-06-24
[ "astro-ph" ]
Peter Schneider (Max-Planck-Institut f\"ur Astrophysik, Garching, Germany)
astro-ph/9512052
A Deep Multicolor Survey II. Initial Spectroscopy and Comparison With Expected Quasar Number Counts
We have used the KPNO 4-meter Mayall telescope to image 0.83 square degrees of sky in six fields at high galactic latitude in six filters spanning 3000-10000\AA\ to magnitude limits ranging from 22.1 to 23.8. As a first use of this database, we have conducted a multicolor survey for quasars. We discuss various methods ...
1995-12-08
2009-10-28
[ "astro-ph" ]
Patrick B. Hall (University of Arizona), Patrick S. Osmer (Ohio State University), Richard F. Green, Alain C. Porter (NOAO), Stephen J. Warren (Imperial College)
astro-ph/9512044
On the Evoution of the Light Elements I. D, He-3, and He-4
The light elements D, \he3, \he4, and \li7 are produced in big bang nucleosynthesis and undergo changes in their abundances due to galactic processing. Since one may observe most of these elements only in contemporary environments, knowledge of the intervening evolution is necessary for determining the observational co...
1995-12-08
2008-11-26
[ "astro-ph" ]
Brian Fields (Univ. of Notre Dame)
astro-ph/9512049
Abundance Determinations from Gamma Ray Spectroscopy
Gamma ray emission lines resulting from accelerated particle bombardment of ambient gas can serve as an important spectroscopic tool for abundance determinations. The method is illustrated by considering the gamma ray line emission observed from solar flares. The observation of similar gamma ray lines from Orion sugges...
1995-12-08
2007-05-23
[ "astro-ph" ]
Reuven Ramaty
astro-ph/9512046
Observation of Extended Red Emission (ERE) in the halo of M82
Low-dispersion spectra have been obtained from 4000 to 9600 \AA~along the axis and across the dusty halo of the galaxy M82. The spectra of the halo are explained in terms of scattering of the galactic light by dust grains: when divided by the spectrum of the galaxy, they reveal a broad emission band, similar to, althou...
1995-12-08
2007-05-23
[ "astro-ph" ]
J.-M. Perrin, S. Darbon, J.-P. Sivan (Observatoire de Haute Provence du CNRS)
astro-ph/9512051
A Deep Multicolor Survey I. Imaging Observations and Catalog of Stellar Objects
We have used the KPNO 4-meter Mayall telescope to image 0.83 square degrees of sky in six fields at high galactic latitude in six filters spanning 3000-10000\AA\ to magnitude limits ranging from 22.1 to 23.8. We have assembled a catalog of 21,375 stellar objects detected in the fields for use primarily in conducting a ...
1995-12-08
2009-10-28
[ "astro-ph" ]
Patrick B. Hall (University of Arizona), Patrick S. Osmer (Ohio State University), Richard F. Green, Alain C. Porter (NOAO), Stephen J. Warren (Imperial College)
astro-ph/9512048
ROSAT PSPC observations of six PG quasars and PHL 1657
We report results from the spectral analysis of pointed ROSAT PSPC observations of six PG quasars and the weak-bump quasar PHL 1657. Disregarding other frequency bands, the PSPC data are represented best by simple power-law source spectra ($dN/dE \propto E^\Gamma$) with a slope $\Gamma = -2.5\pm 0.4$ and do not show ev...
1995-12-08
2007-05-23
[ "astro-ph" ]
Joerg P. Rachen, Karl Mannheim and Peter L. Biermann
astro-ph/9512045
Ultrasoft transient X-ray emission from AGN
We report some remarkable and unexpected results of optical/UV/X-ray follow-up observations of bright soft X-ray selected AGN from the ROSAT All-Sky-Survey. The majority of these AGN are rather anonymous Seyfert galaxies, mostly of the narrow-line Seyfert 1 subtype (nlSy1). We confirm the well-known X-ray variability b...
1995-12-08
2007-05-23
[ "astro-ph" ]
K. Mannheim, D. Grupe, K. Beuermann, H.-C. Thomas, and H.H. Fink
astro-ph/9512040
Interaction in the Bimodal Galaxy Cluster A3528
X-ray and radio continuum observations of the bimodal cluster A3528 in the Shapley Supercluster are presented. From a ROSAT PSPC pointed observation we find a marginal tendency of the intracluster gas to be hotter in the region between the two subclusters. This effect can be interpreted as the signature of interaction ...
1995-12-07
2015-06-24
[ "astro-ph" ]
S. Schindler
astro-ph/9512035
H I, H II, and R-Band Observations of a Galactic Merger Sequence
We present high-quality aperture synthesis observations of the neutral hydrogen distribution in a sample of five galactic systems believed to be involved in progressive stages of merging: Arp295, NGC4676, NGC520, NGC3921, and NGC7252. These data are supplemented by wide-field images taken through a narrow band Halpha f...
1995-12-07
2009-10-28
[ "astro-ph" ]
J.E. Hibbard (IfA), J.H. van Gorkom (Columbia Univ)
astro-ph/9512033
The Serendipitous Discovery of a Group or Cluster of young Galaxies at z=2.40 in Deep Hubble Space Telescope WFPC2 Images
We report the serendipitous discovery of a group or cluster of young galaxies at $z\simeq$2.40 in a 24-orbit HST/WFPC2 exposure of the field around the weak radio galaxy 53W002. Potential cluster members were identified on ground-based narrow-band redshifted Ly$\alpha$ images and confirmed via spectroscopy. In additi...
1995-12-07
2016-08-30
[ "astro-ph" ]
Sebastian M. Pascarelle (ASU), Rogier A. Windhorst (ASU), Simon P. Driver (ASU), Eric J. Ostrander (ASU), William C. Keel (UoAl)
astro-ph/9512037
Modeling the Clustering of Objects
I review the main steps made so far towards the construction of a (semi) analytical model for describing the growth history of bound virialized objects or haloes in the gravitational instability scenario. I mainly focus on those models relying on the spherical collapse approximation which have led to the most complete ...
1995-12-07
2007-05-23
[ "astro-ph" ]
E. Salvador-Sole (University of Barcelona)
astro-ph/9512042
Isolating the Foreground of the X-Ray Background
The foreground component of the X-ray Background (XRB) can be studied by cross-correlating its intensity with galaxy catalogs. We computed the two-point cross-correlation function $W_{xg}$ between 67 {\em Einstein} X-ray fields and the APM galaxy catalog. We detected a signal with an amplitude of $W_{xg} = .04 \pm .01$...
1995-12-07
2007-05-23
[ "astro-ph" ]
A. Refregier, D.J. Helfand (Columbia University), and R.G. McMahon (Cambridge University)
astro-ph/9512036
Chaos and Tidal Capture
We review the tidal capture mechanism for binary formation, an important process in globular cluster cores and perhaps open cluster cores. Tidal capture binaries may be the precursors for some of the low-mass X-ray binaries observed in abundance in globular clusters. They may also play an important role in globular clu...
1995-12-07
2007-05-23
[ "astro-ph" ]
Rosemary A. Mardling (Monash Univ.)
astro-ph/9512039
Probing Cluster Potentials through Gravitational Lensing of Background X-Ray Sources
We examine the gravitational lensing effect of a foreground galaxy cluster on the number count statistics of background X-ray sources. The lensing produces a deficit in the number of resolved sources in a ring close to the critical radius of the cluster. This deficit could be detected at the $\sim 3\sigma$ level with t...
1995-12-07
2007-05-23
[ "astro-ph" ]
Alexandre Refregier and Abraham Loeb
astro-ph/9512041
The WARPS survey for faint Clusters of Galaxies
The WARPS cluster survey is based on the ROSAT PSPC archive of pointed observations. It includes extended X-ray sources, detected with the Voronoi Tessellation and Percolation algorithm (VTP), and point-like X-ray sources with non-stellar optical counterparts. It is designed to minimize selection effects whilst coverin...
1995-12-07
2007-05-23
[ "astro-ph" ]
L.R. Jones, C.A. Scharf, E.Perlman (NASA/Goddard), H. Ebeling (IoA), G. Wegner (Dartmouth), M. Malkan (UCLA)
astro-ph/9512043
Neutral Hydrogen in the Ringed Barred Galaxies NGC 1433 and NGC 6300
We have made observations of the \ion{H}{1} in the southern ringed barred spiral galaxies NGC~1433 and NGC~6300 with the Australia Telescope Compact Array (ATCA), the main goal being to test the resonance theory for the origin of these rings. NGC~1433 is the prototypical ringed barred spiral, and displays distinct \ion...
1995-12-07
2009-10-28
[ "astro-ph" ]
Stuart D. Ryder (1, now 2), Ronald J. Buta (1), Hector Toledo (1), Hemant Shukla (1), Lister Staveley-Smith (3), Wilfred Walsh (2,3) ((1) University of Alabama, (2) University of New South Wales, (3) Australia Telescope National Facility)
astro-ph/9512038
Neutrino Scattering in Strangeness-Rich Stellar Matter
We calculate neutrino cross sections from neutral current reactions in dense matter containing hyperons. We show that Sigma- hyperons give significant contributions. To lowest order, the contributions from the neutral Lambda and Sigma0, which have zero hyper-charge, vanish. However, their presence furnishes baryon numb...
1995-12-07
2008-02-03
[ "astro-ph" ]
Sanjay Reddy and Madappa Prakash
astro-ph/9512034
LiBeB Production by Nuclei and Neutrinos
The production of LiBeB isotopes by nuclear and neutrino spallation are compared in the framework of galactic evolutionary models. As motivated by $\gamma$-ray observations of Orion, different possible sources of low-energy C and O nuclei are considered, such as supernovae of various masses and WC stars. We confirm tha...
1995-12-07
2009-09-15
[ "astro-ph" ]
Elisabeth Vangioni-Flam, Michel Cass\'e, Brian D. Fields, and Keith A. Olive
astro-ph/9512030
The Proximity Effect of QSO Metal Line Absorption Systems on Lyman $\alpha$ Forests
The proximity effect of metal line absorption systems in spectra of high redshift quasars and quasar pairs is investigated through the distribution of \Lyalpha forests. No strong proximity effect is found down to 500 km/sec away from a metal line absorption system for lyman $\alpha$ clouds with $13.3\le\log\NHI <13.8$ ...
1995-12-06
2007-05-23
[ "astro-ph" ]
Xiangdong Shi (Queen's University)
astro-ph/9512023
The Inverse-Compton And Extragalactic Components Of The Diffuse Gamma-Ray Emission
We present spectra of the inverse-Compton and extragalactic components of the high-energy gamma-radiation based on an analysis of the emission at high galactic latitudes ($\vert$b$\vert$ $\geq$ $30\deg$). We correlate the gamma-ray intensity with a model consisting of an isotropic component, a component proportional to...
1995-12-06
2009-10-28
[ "astro-ph" ]
Andrew Chen (1), Joseph Dwyer (1, now 2), Philip Kaaret (1) ((1) Columbia University, (2) University of Maryland at College Park)
astro-ph/9512024
Are the Lyman alpha forest "clouds" expanding pancakes?
The large sizes of Lyman alpha ``clouds'' inferred from coincident absorption in the spectrum of close quasar pairs suggests that these are transient flattened structures of small overdensity. It is argued that the observed absorbers should be preferentially located in underdense regions of the universe and should typi...
1995-12-06
2007-05-23
[ "astro-ph" ]
Martin G. Haehnelt (Max-Planck-Institut fuer Astrophysik, Garching)
astro-ph/9512025
The Line Emission from the Circumstellar Gas Around SN 1987A
The narrow emission lines from the inner ring around SN 1987A during the first $\sim 2000$ days are modeled. The analysis extends that in Lundqvist & Fransson (1991) to include an improved description for the geometry, a multi-density structure of the emitting gas, results from improved calculations for the evolu- tion...
1995-12-06
2009-10-28
[ "astro-ph" ]
P. Lundqvist, C. Fransson
astro-ph/9512026
Evidence for Secular Evolution in Late-Type Spirals
We combine deep optical and IR photometry for 326 spiral galaxies from two recent galaxy samples and report that the surface brightness profiles of late-type spirals are best fit by two exponentials. Moreover, the ratio of bulge and disk scale lengths takes on a restricted range of values and is uncorrelated with Hubbl...
1995-12-06
2009-10-28
[ "astro-ph" ]
S. Courteau (NOAO/KPNO), R.S. de Jong (Durham), A.H. Broeils (Cornell)
astro-ph/9512029
A note on the neutrino decay line and the possibilities of its detection
Using simple physical reasoning we have estimated the wavelengths and line-widths of spectral lines arising from the decays of massive neutrinos. We have, also, to some extent, discussed the possible consequences of these decays in observable astrophysical settings. We have compared our conclusions with the predictions...
1995-12-06
2007-05-23
[ "astro-ph" ]
Srdjan Samurovic (People's Observatory), Vladan Celebonovic (Institute of Physics)
astro-ph/9512028
A search for distant X-ray galaxy clusters
We report on the progress of our search for serendipitous distant X-ray galaxy clusters in the ROSAT PSPC pointed observations archive. The initial aim of our work is to measure the X-ray luminosity function of clusters down to 4 x 10^-14 erg cm^-2 s^-1 and so test the claims of cluster evolution at moderate redshifts....
1995-12-06
2007-05-23
[ "astro-ph" ]
D.J. Burke (1), C.A. Collins (2), R.C. Nichol (3), A.K. Romer (4), B. Holden (3), R.M. Sharples (1) and M.P. Ulmer (4) ((1) Durham University, (2) Liverpool John Moores University, (3) University of Chicago, (4) Northwestern University)
astro-ph/9512032
Broad Absorption Line QSOs Observed by the ROSAT PSPC
Recent results from the ROSAT All-Sky Survey (RASS) have shown that broad absorption line (BAL) QSOs are either highly absorbed or underluminous in the soft X-ray bandpass. Here, we extend this work by analyzing all known bona fide BALQSOs observed within the inner 20' of the ROSAT PSPC. This sample includes both targe...
1995-12-06
2009-10-28
[ "astro-ph" ]
Paul J. Green and Smita Mathur (CfA)
astro-ph/9512027
Non-Explosive Hydrogen Burning: Where Do We Stand?
The impact of nuclear physics uncertaintites on the abundances predicted to emerge from the cold CNO, NeNa and MgAl modes of hydrostatic hydrogen burning is discussed in the framework of a simple parametric model. In addition of being able to mimic qualitatively detailed stellar model predictions, these parametric calc...
1995-12-06
2007-05-23
[ "astro-ph" ]
M. Arnould, N. Mowlavi, and A. Champagne
astro-ph/9512031
Cosmological Inflation and the Nature of Time
Recent advances in observational cosmology are changing the way we view the nature of time. In general relativity, the freedom in choosing a time hypersurface has hampered the implementation of the theory. Fortunately, Hamilton-Jacobi theory enables one to describe all time hypersurfaces on an equal footing. Using an e...
1995-12-06
2007-05-23
[ "astro-ph", "gr-qc", "hep-ph" ]
D. S. Salopek
astro-ph/9512020
Estimates of Doppler Factors, Outflow Angles, and Bulk Lorentz Factors for a Sample of Compact Radio Sources
Two key results are presented in this paper. First, equipartition Doppler factors have been estimated for a sample of 105 sources with previously estimated inverse Compton Doppler factors. The different categories of active galactic nuclei (AGN) have different ranges and typical values of the Doppler factor; lobe domin...
1995-12-05
2008-02-03
[ "astro-ph" ]
R. A. Daly, E. J. Guerra, A. Guijosa
astro-ph/9512017
Detection of H-alpha emission from the Magellanic Stream: evidence for an extended gaseous Galactic halo
We have detected faint, diffuse H$\alpha emission from several points along the Magellanic Stream, using the Rutgers Fabry--Perot Interferometer at the CTIO 1.5-m telescope. At points on the leading edges of the H I clouds MS II, MS III, and MS IV, we detect H$\alpha emission of surface brightness $0.37 \pm 0.02$ Rayle...
1995-12-05
2008-11-26
[ "astro-ph" ]
Benjamin J. Weiner and T.B. Williams (Rutgers Univ.)
astro-ph/9512019
Phase Lags and Coherence of X-Ray Variability in Black Hole Candidates
The ``low'' (hard or ``non-thermal'') state of black hole candidates is sometimes modelled via an optically thick, hot Compton cloud that obscures a softer input source such as an accretion disk. In these models the observed output spectra consist entirely of photons reprocessed by the cloud, making it difficult to ext...
1995-12-05
2015-06-24
[ "astro-ph" ]
Michael A. Nowak (JILA), and Brian A. Vaughan (Caltech)
astro-ph/9512018
Magnetic braking of T Tauri stars
We construct models for the rotation rates of T Tauri stars whose spin is regulated by magnetic linkage between the star and a surrounding accretion disc. Our models utilise a time-dependent disc code to follow the accretion process and include the effects of pre-main-sequence stellar evolution. We find that the initia...
1995-12-05
2015-06-24
[ "astro-ph" ]
P.J. Armitage and C.J. Clarke
astro-ph/9512022
Search for neutron star spin periods in X-ray bursts
We report a search for pulsations in 147 Type 1 X-ray bursts observed with EXOSAT in 10 X-ray burst sources. Instead of treating each burst separately, we incoherently averaged the power spectra of all of the bursts of a given burster to improve statistics. No periodicities were detected; 99% confidence upper limits on...
1995-12-05
2007-05-23
[ "astro-ph" ]
H. C. Jongert and M. van der Klis (Astronomical Institute ``Anton Pannkekoek'', University of Amsterdam)
astro-ph/9512016
Small Scale Structure and High Redshift HI
Cosmological simulations with gas dynamics suggest that the Lyman-alpha forest is produced mainly by "small scale structure" --- filaments and sheets that are the high redshift analog of today's galaxy superclusters. There is no sharp distinction between Lyman-alpha clouds and "Gunn-Peterson" absorption produced by the...
1995-12-05
2016-01-27
[ "astro-ph" ]
David H. Weinberg, Lars Hernquist, Neal Katz, Jordi Miralda-Escude
astro-ph/9512021
Determining cosmic microwave background anisotropies in the presence of foregrounds
Separating foregrounds from the signal is one of the big challenges in cosmic microwave background (CMB) experiments. A simple way to estimate the CMB temperature in a given pixel is to fit for the amplitudes of the CMB and the various foreground components. The variance squared of this estimator is shown to be equal t...
1995-12-05
2009-10-28
[ "astro-ph" ]
Scott Dodelson
astro-ph/9512011
The Real Space Correlation Function Measured from the APM Galaxy Survey
We present a determination of the real space correlation function for galaxies in the APM Survey, with magnitudes in the range $17 < b_J < 20$. We recover a power law form for the correlation function $\xi(r) = (r/4.5)^{-1.7}$ on scales $r < 4 Mpc/h$, for a flat universe and clustering that is fixed in comoving coordin...
1995-12-04
2015-06-24
[ "astro-ph" ]
C.M. Baugh (Univ. of Durham, UK)
astro-ph/9512014
Cosmological Constant and Statistical Lensing of Giant Arcs
Using a singular isothermal sphere model for the matter distribution of foreground clusters of galaxies, we study the statistics of giant arcs in flat cosmologies with and without a cosmological constant. We find that the relative number of arcs predicted within $z=1$ in a universe with $\Omega_0=0.3$ and $\lambda_0 \e...
1995-12-04
2009-10-28
[ "astro-ph" ]
Xiang-Ping Wu (Beijing Astronomical Observatory) and Shude Mao (Harvard-Smithsonian Center for Astrophysics)
astro-ph/9512013
Simulating Galaxy Formation
A review on numerical simulations of galaxy formation is given. Different numerical methods to solve collisionless and gas dynamical systems are outlined and one particular simulation technique, Smoothed Particle Hydrodynamics, is discussed in some detail. After a short discussion of the most relevant physical processe...
1995-12-04
2007-05-23
[ "astro-ph" ]
Matthias Steinmetz
astro-ph/9512012
A Supersoft X-Ray Binary in the Small Magellanic Cloud
Photometric observations of the supersoft X-ray source 1E 0035.4-7230 obtained during two years reveal that the very blue optical counterpart (V (maximum)=20.2, B-V=-0.15, U-B=-1.06) undergoes nearly sinusoidal variations with a period of 0.1719256 days and an amplitude of Delta V~0.3 mag. ROSAT observations show the X...
1995-12-04
2009-10-28
[ "astro-ph" ]
P.C. Schmidtke, A.P. Cowley, T.K. McGrath, J.B. Hutchings and D. Crampton
astro-ph/9512015
Globular Cluster Photometry with the Hubble Space Telescope. V. WFPC2 Study of M15's Central Density Cusp
We describe images of the center of the dense globular cluster M15 (NGC 7078) obtained with the Hubble Space Telescope Wide Field and Planetary Camera 2 (WFPC2). Data taken in the F336W, F439W, and F555W filters (approximately U, B, and V) are used to study the surface density distribution of the $\sim3\times10^4$~star...
1995-12-04
2009-10-28
[ "astro-ph" ]
Puragra Guhathakurta, Brian Yanny, Donald P. Schneider, and John N. Bahcall
astro-ph/9512010
Four new active galaxies with steep soft X-ray spectra
We have discovered four AGN in the ROSAT all-sky-survey data with very steep X-ray spectra. We apply several models to these X-ray spectra with emphasis on warm absorber models which give an adequate description of the data. We report on the follow-up optical and radio observations which allow the identification of thr...
1995-12-04
2007-05-23
[ "astro-ph" ]
J. Greiner, R. Danner, N. Bade, G.A. Richter, P. Kroll, S. Komossa
astro-ph/9512009
Galaxy Formation and Large-Scale Bias
We outline a simple approach to understanding the physical origin of bias in the distribution of galaxies relative to that of dark matter. The first step is to specify how collapsed, virialized halos of dark matter trace the overall matter distribution. The next step is to make a connection between halos and the lumino...
1995-12-04
2015-06-24
[ "astro-ph" ]
Guinevere Kauffmann, Adi Nusser & Matthias Steinmetz
astro-ph/9512008
Large scale clustering from Non-Gaussian texture models
A basic ingredient to understand large scale fluctuations in our present day Universe is the initial conditions. Using N-body simulations, we compare the clustering that arises from Gaussian and non-Gaussian initial conditions. The latter is motivated by a global texture model which has initial $J$-order correlations $...
1995-12-03
2009-10-28
[ "astro-ph", "hep-ph" ]
E. Gaztanaga (CSIC, Blanes) and P. Mahonen (Univ. Oulu)
astro-ph/9512007
Reconnecting Magnetic Flux Tubes as a Source of In Situ Acceleration in Extragalactic Radio Sources
Many extended extragalactic radio sources require a local {\it in situ\/} acceleration mechanism for electrons, in part because the synchrotron lifetimes are shorter than the bulk travel time across the emitting regions. If the magnetic field in these sources is localized in flux tubes, reconnection may occur between r...
1995-12-03
2009-10-28
[ "astro-ph" ]
Eric G. Blackman (Institute of Astronomy, Cambridge UK)
astro-ph/9512006
A Balloon-Borne Millimeter-Wave Telescope for Cosmic Microwave Background Anisotropy Measurements
We report on the characteristics and design details of the Medium Scale Anisotropy Measurement (MSAM), a millimeter-wave, balloon-borne telescope that has been used to observe anisotropy in the Cosmic Microwave Background Radiation (CMBR) on 0\fdg5 angular scales. The gondola is capable of determining and maintaining a...
1995-12-02
2009-10-28
[ "astro-ph" ]
D. J. Fixsen, E. S. Cheng, D. A. Cottingham, W. C. Folz, C. A. Inman, M. S. Kowitt, S. S. Meyer, L. A. Page, J. L. Puchalla, J. E. Ruhl, and R. F. Silverberg
astro-ph/9512005
Main Sequence Masses and Radii from Gravitational Redshifts
Modern instrumentation makes it possible to measure the mass to radius ratio for main sequence stars in open clusters from gravitational redshifts. For stars where independent information is available for either the mass or the radius, this application of general relativity directly determines the other quantity. Appli...
1995-12-02
2009-10-28
[ "astro-ph" ]
Ted von Hippel (University of Wisconsin, USA)
astro-ph/9512004
Confirmation of high deuterium abundance in QSO absorbers
We present a new analysis of a Keck spectrum of Q0014+813, with a new model of the $z=3.32$ absorbing cloud. We fit Lyman series absorption of the dominant HI components, including components identified with hydrogen and associated deuterium at two discrete velocities, with thermal line broadening of each species. The ...
1995-12-01
2009-10-28
[ "astro-ph" ]
M. Rugers and C. J. Hogan (University of Washington)
astro-ph/9512001
Clustering of Faint Galaxies: $\w $, Induced by Weak Gravitational Lensing
Weak gravitational lensing by large scale structure affects the number counts of faint galaxies through the ``magnification bias'' and thus affects the measurement of the angular two-point correlation function $\w $. At faint magnitudes the clustering amplitude will decrease differently with limiting magnitude than exp...
1995-12-01
2007-05-23
[ "astro-ph" ]
Jens Verner Villumsen (Max Planck Institute fur Astrophysik, Garching, Germany)
astro-ph/9512003
Cosmic Deuterium and Baryon Density
Quasar absorption lines now permit a direct probe of deuterium abundances in primordial material, with the best current estimate $ (D/H)=1.9\pm 0.4 \times 10^{-4}$. If this is the universal primordial abundance $(D/H)_p$, Standard Big Bang Nucleosynthesis yields an estimate of the mean cosmic density of baryons, $\eta_...
1995-12-01
2008-02-03
[ "astro-ph" ]
Craig J. Hogan (University of Washington)
astro-ph/9512002
Warm Gas at High Redshift - Clues to Gravitational Structure Formation from Optical Spectroscopy of Lyman Alpha Absorption Systems
We discuss the effects of gravitational collapse on the shape of absorption line profiles for low column density (log N(HI) < 14) Lyman Alpha forest clouds and argue by comparison with cosmological simulations that Lyman alpha forest observations show the signs of ongoing gravitational structure formation at high redsh...
1995-12-01
2016-01-27
[ "astro-ph" ]
Michael Rauch (Astronomy Dept., Caltech)
astro-ph/9511150
Gravitational `Convergence' and Cluster Masses
Two colour photometry of the cluster A1689 reveals a `relative magnification-bias' between lensed blue and red background galaxies, arising from a dependence of the faint galaxy count-slope on colour. The colour distribution is skewed blueward of the far field, allowing us to measure the cluster magnification and to un...
1995-12-01
2007-05-23
[ "astro-ph" ]
Tom Broadhurst
astro-ph/9511148
Doppler peaks and all that: CMB anisotropies and what they can tell us
The power spectrum of fluctuations in the cosmic microwave background (CMB) depends on most of the key cosmological parameters. Accurate future measurements of this power spectrum might therefore allow us to determine h, Omega, Omega_b, Lambda, n, T/S, etc, with hitherto unprecedented accuracy. In these lecture notes, ...
1995-11-30
2007-05-23
[ "astro-ph" ]
Max Tegmark
astro-ph/9511149
Simulations of Galaxy Formation in Hierarchically Clustering Universes
I review the results of recent N--body/hydrodynamical simulations of the formation of galaxies in hierarchical universes, with special emphasis on the structure of dark matter halos, as well as on the mass and angular momentum of gaseous disks that assemble at the center of these halos.
1995-11-30
2007-05-23
[ "astro-ph" ]
Julio F. Navarro (Steward Observatory, University of Arizona)
astro-ph/9511146
Optimal Smoothing for N-Body Codes
In any collisionless N-body code, there is an optimal choice for the smoothing parameter that minimizes the average error in the force evaluations. We show how to compute the optimal softening length in a direct-summation code and demonstrate that it varies roughly as 1/N^(1/3).
1995-11-29
2009-10-28
[ "astro-ph" ]
David Merritt (Rutgers)
astro-ph/9511141
Hubble Space Telescope Counts of Elliptical Galaxies: Constraints on Cosmological Models ?
The interpretation of galaxy number counts in terms of cosmological models is fraught with difficulty due to uncertainties in the overall galaxy population (mix of morphological types, luminosity functions etc.) and in the observations (loss of low surface brightness images, image blending etc.). Many of these can be o...
1995-11-29
2016-08-30
[ "astro-ph" ]
Simon P. Driver (ASU), Rogier A. Windhorst (ASU), Steven Phillipps (Univ. Bristol), Paul D. Bristow (Univ. Bristol)
astro-ph/9511142
The Production of Ti44 and Co60 in Supernova
The production of the radioactive isotopes $^{44}$Ti and $^{60}$Co in all types of supernovae is examined and compared to observational constraints including Galactic $\gamma$--ray surveys, measurements of the diffuse 511 keV radiation, $\gamma$--ray observations of Cas A, the late time light curve of SN 1987A, and iso...
1995-11-29
2009-10-28
[ "astro-ph" ]
F.X. Timmes, S.E. Woosley, D.H. Hartmann & R.D. Hoffman
astro-ph/9511145
Knots in Magnetized Relativistic Jets and Their Simulations
Bright features (`knots') in extragalactic jets are commonly associated with reheating of charged particles in regions with shocks or strong compression. We find a natural appearance of nozzles in simulations of toroidally magnetized jets, and propose this as a generic mechanism of knotted structures such as in the jet...
1995-11-29
2007-05-23
[ "astro-ph" ]
Maurice H.P.M. van Putten
astro-ph/9511144
The Tucana dwarf galaxy
Deep CCD photometry (NTT, HST data) for the dwarf galaxy in Tucana is presented, down to V=27.5. Distance modulus and metallicity are derived, together with an estimate of the age of the galaxy.
1995-11-29
2007-05-23
[ "astro-ph" ]
Marco Castellani (1), Gianni Marconi (1), Roberto Buonanno (1) ((1) Osservatorio Astronomico di Roma, Monte Porzio)
astro-ph/9511147
Constraints on the Global Mass-to-Light Ratios and Extent of Dark Matter Halos in Globular Clusters and Dwarf Spheroidals
The detection of stars in the process of being tidally removed from globular clusters and dwarf spheroidals in the Galaxy's halo provides a strong constraint on their mass to light ratios and on the extent of their possible dark matter halos. If a significant dark matter component existed either within or beyond the ob...
1995-11-29
2009-10-28
[ "astro-ph" ]
Ben Moore (UC Berkeley)
astro-ph/9511143
An Inflationary Model with an Exact Perturbation Spectrum
We present a new, exact scalar field cosmology for which the spectrum of scalar (density) perturbations can be calculated exactly. We use this exact result to the probe the accuracy of approximate calculations of the perturbation spectrum.
1995-11-29
2009-10-28
[ "astro-ph", "gr-qc" ]
Richard Easther (Waseda University)
astro-ph/9511135
Caught in the act: The identification of the galaxies responsible for the faint blue excess
We summarise recent Hubble Space Telescope results on the morphology of faint field galaxies. Our two principle results are: (1) the galaxies responsible for the faint blue excess have late-type/irregular morphology and (2) the number counts of normal galaxies, ellipticals and early-type spirals, are well fit by standa...
1995-11-28
2007-05-23
[ "astro-ph" ]
Simon P. Driver (ASU), Rogier A. Windhorst (ASU), Richard E. Griffiths (JHU)
astro-ph/9511140
Strong Angular Clustering of Very Blue Galaxies: Evidence of a Low Redshift Population
We have studied galaxy two-point angular correlations as a function of color using 4-m plate photometry in two independent fields. Each field consists of over 2900 galaxies with magnitudes 20<B_J <23.5 in an area of approximately 750 arcmin^2 . We find that the autocorrelation amplitude of the bluest 15% of galaxies is...
1995-11-28
2009-10-28
[ "astro-ph" ]
Stephen D. Landy (Carnegie Observatories), Alexander S. Szalay (Johns Hopkins Univ.), David C. Koo (Univ. of CA - Santa Cruz)
astro-ph/9511139
The Fundamental Plane for cluster E and S0 galaxies
We have analyzed the Fundamental Plane (FP) for a sample of 226 E and S0 galaxies in ten clusters of galaxies. For photometry in Gunn r the best fitting plane is log r_e=1.24 log sigma - 0.82 log <I>_e + cst. The scatter is 0.084 in log r_e. The slope of the FP is not significantly different from cluster to cluster. Th...
1995-11-28
2015-06-24
[ "astro-ph" ]
Inger Jorgensen (McDonald Observatory), Marijn Franx, Per Kjaergaard
astro-ph/9511137
LensMEM: A Gravitational Lens Inversion Algorithm Using the Maximum Entropy Method
We present a new algorithm for inverting poorly resolved gravitational lens systems using the maximum entropy method (MEM). We test the method with simulations and then apply it to an 8 GHz VLA map of the radio ring lens MG1654+134. We model the lens as a singular isothermal sphere embedded in an external shear field a...
1995-11-28
2009-10-28
[ "astro-ph" ]
S. Wallington, C.S. Kochanek & R. Narayan (Harvard-Smithsonian Center For Astrophysics)
astro-ph/9511136
Damping of GRR instability by direct URCA reactions
The role of direct URCA reactions in damping of the gravitational radiation driven instability is discussed. The temperature at which bulk viscosity suppresses completely this instability is calculated. The results are obtained analytically using recent calculations performed in the case of bulk viscosity due to the ...
1995-11-28
2011-05-23
[ "astro-ph" ]
J.L. Zdunik
astro-ph/9511138
The Single-Degenerate Scenario for Type Ia SNe in Cosmic Perspective
The occurrence and properties of Type Ia supernovae (SNe Ia) in single-degenerate binary systems (white dwarf [WD] + nondegenerate companion) is examined for galaxies of different types, and as a function of redshift. The rates and characteristics (peak luminosities, expansion velocities of the ejecta) expected from th...
1995-11-28
2009-10-28
[ "astro-ph" ]
R. Canal, P. Ruiz-Lapuente and A. Burkert
astro-ph/9511134
Morphological number-counts from the ultradeep HST images
We discuss the observations leading to the Faint Blue Galaxy problem and the uncertainties upon which faint galaxy models are based. Using deep Hubble Space Telescope (HST) imaging with the Wide Field Planetary Camera (WFPC2), we show how morphological information has been used to shed new light on the problem. Initial...
1995-11-28
2007-05-23
[ "astro-ph" ]
Simon P. Driver (ASU), Rogier A. Windhorst (ASU), Richard E. Griffiths (JHU)
astro-ph/9511132
The morphological mix of field galaxies to I=24.25 magnitudes (b=26 magnitudes) from a deep Hubble Space Telescope WFPC2 image
We determine the morphological mix of field galaxies down to $m_{I}\simeq 24.25$ mag ($m_{B}\sim 26.0$ mag) from a single ultradeep HST WFPC2 image in both the $V_{606}$ and $I_{814}$ filters. In total, we find 227 objects with $m_{I}\le 24.5$ mag and classify these into three types: ellipticals (16%), early-type spira...
1995-11-28
2016-08-30
[ "astro-ph" ]
Simon P. Driver (ASU), Rogier A. Windhorst (ASU), Eric J. Ostrander (ASU), William C. Keel (UoAl), Richard E. Griffiths (JHU), Kavan U. Ratnatunga (JHU)
astro-ph/9511133
Are disappearing dwarfs just lying low ?
Recent redshift surveys have shown that the excess galaxies seen in faint galaxy number counts (above those expected given the local galaxy luminosity function) are not evolved giants at high redshifts, but low to moderate luminosity objects at more modest redshifts. This has led to the suggestion that there was once a...
1995-11-28
2015-06-24
[ "astro-ph" ]
Steven Phillipps (Univ. Bristol), Simon P. Driver (Arizona State Univ)
astro-ph/9511131
The proximity effect on the Lyman alpha forest due to a a foreground QSO
The influence of a foreground QSO on the lyman a forest of another QSO with higher redshift has been investigated by analyzing the spectra of three such objects at redshifts $z=2 - 2.7$. This influence is not contaminated by any projection effects, as opposed to the inverse effect along the line of sight, where incompl...
1995-11-28
2015-06-24
[ "astro-ph" ]
A. Fernandez-Soto (1 and 2), X. Barcons (1), R. Carballo (1 and 2), J.K. Webb (3) ((1) IFCA (CSIC-UC)-Santander-SPAIN, (2) Dpt. Fisica Moderna (UC)-Santander-SPAIN, (3) UNSW-Sydney-AUSTRALIA)