id
large_stringlengths
9
16
title
large_stringlengths
1
382
abstract
large_stringlengths
3
6.09k
publish_date
date32
update_date
date32
categories
large listlengths
1
13
authors
large_stringlengths
3
62.8k
astro-ph/9407030
The detectability of planetary companions of compact galactic objects from their effects on microlensed lightcurves of distant stars
We discuss a possible method for detection of dark companions of galactic objects of stellar mass. Such binary systems are likely to occur in the galactic disk and possibly also in the halo. The high incidence of binary and higher-multiplicity systems in the solar neighborhood, if indicative of the galactic disk at lar...
1994-07-11
2009-10-22
[ "astro-ph" ]
A.D. Bolatto and E.E. Falco
astro-ph/9407027
Structure Formation in the Universe from Texture Induced Fluctuation
The topic of this letter is structure formation with topological defects. We first present a partially new, fully local and gauge invariant system of perturbation equations to treat microwave background and dark matter fluctuations induced by topological defects (or any other type of seeds). We show that this treatment...
1994-07-09
2010-11-01
[ "astro-ph" ]
Ruth Durrer, Zhi-hong Zhou
astro-ph/9407025
Radial cluster lensing: A simple differential equation describing arclet fields
Clusters of galaxies acting as gravitational lenses deform the images of background galaxies. For small galaxies the deformation is determined by the local properties of the lens (shear, convergence). Small circular shaped galaxies are seen as small ellipses. The orientation and axial ratio of the ellipses could then b...
1994-07-08
2007-05-23
[ "astro-ph" ]
T.Schramm and R.Kayser
astro-ph/9407026
The Inflationary Role of the Dilaton in String Cosmology
It is stressed that the kinematical problems of the standard cosmological model can be solved by a phase of accelerated contraction of the cosmic scale factor. Such a behaviour is only a particular case of a more general ``pre-big-bang" inflationary scenario, arising naturally in a string cosmology context, and driven ...
1994-07-08
2009-10-22
[ "astro-ph", "gr-qc", "hep-th" ]
M.Gasperini
astro-ph/9407022
Bright Stars in the Galactic Globular M5
We present a CCD investigation of the galactic globular M5 aimed to increase the statistical relevance of the available sample of evolving bright stars. Previous investigations, limited to the outer cluster region, have been extended toward the cluster center, more than doubling the number of observed luminous stars. O...
1994-07-07
2009-10-22
[ "astro-ph" ]
E.Brocato, V.Castellani, V.Ripepi
astro-ph/9407024
Baryonic Dark Matter
In the first two of these lectures, I present the evidence for baryonic dark matter and describe possible forms that it may take. The final lecture discusses formation of baryonic dark matter, and sets the cosmological context.
1994-07-07
2009-09-25
[ "astro-ph" ]
Joseph Silk
astro-ph/9407019
New Bounds on Omega Baryons from Observational Big Bang Nucleosynthesis
We re-examine the systematic errors in the determination of the primordial helium abundance, $Y_{\rm P}$. We find that the systematics are significantly larger than the statistical errors. The uncertainty in (the determination of) $Y_{\rm P}$, is thus, larger than is currently claimed. Furthermore, most of the systemat...
1994-07-07
2009-09-25
[ "astro-ph" ]
Dimitar D. Sasselov and Dalia Goldwirth
astro-ph/9407021
Reconstructing the Inflaton Potential
A review is presented of recent work by the authors concerning the use of large scale structure and microwave background anisotropy data to determine the potential of the inflaton field. The importance of a detection of the stochastic gravitational wave background is emphasised, and some preliminary new results of test...
1994-07-07
2007-05-23
[ "astro-ph" ]
Edward W Kolb, Mark Abney, Edmund J Copeland, Andrew R Liddle and James E Lidsey
astro-ph/9407023
Dynamical and Observable Constraints on RAMBOs: Robust Associations of Massive Baryonic Objects
If the halo dark matter consists of faint baryonic stars, then these objects probably formed at an early epoch within large associations with similar dynamical properties to globular or open clusters. We use the luminosity function of globular clusters as a function of galactocentric distance to provide a very strong c...
1994-07-07
2009-10-22
[ "astro-ph" ]
Ben Moore and Joseph Silk
astro-ph/9407020
Steady state shocks in accretion disks around a Kerr black hole
Results of numerical simulations of shock solutions in a geometrical thin accretion disk around a Kerr black hole (BH) are presented. Using the smoothed particle hydrodynamics (SPH) technique, the influence of the central object is included by means of an effective potential, We first present the theory of standing sho...
1994-07-07
2015-06-24
[ "astro-ph", "gr-qc" ]
H. Sponholz and D. Molteni
astro-ph/9407017
Echo Mappping of the Broad Line Region of AGNs -- A Critical Appraisal
The results of recent AGN monitoring campaigns confirm the ``big picture'' of the echo paradigm, but the details of the emission-line light curves cannot be accurately reproduced with only the simplest assumptions, some of which must be invalid. I discuss possible solutions. I present some preliminary optical light cur...
1994-07-06
2007-05-23
[ "astro-ph" ]
Dan Maoz
astro-ph/9407016
Equilibrium State of a Massless Self-Interacting Scalar Field in the De Sitter Background
Behaviour of a weekly self-interacting scalar field with a small mass in the de Sitter background is investigated using the stochastic approach (including the case of a double-well interaction potential). Existence of the de Sitter invariant equilibrium quantum state of the scalar field in the presence of interaction i...
1994-07-06
2010-04-06
[ "astro-ph", "hep-th" ]
Alexei A. Starobinsky and Jun'ichi Yokoyama
astro-ph/9407018
The fate of central black holes in merging galaxies
This paper presents results of a series of numerical N-body experiments that describe the merging of galaxy pairs containing a massive black hole in their core. The aim is to study the orbital evolution of the two black holes through the merger event. It is found that merging does NOT lead to the formation of a CLOSE b...
1994-07-06
2015-06-24
[ "astro-ph" ]
F. Governato, M. Colpi and L. Maraschi
astro-ph/9407014
The Optical Depth to Gravitational Microlensing in the Direction of the Galactic Bulge
We present the analysis of the first two years of the OGLE search for gravitational lenses towards the Galactic bulge. We detected 9 microlensing events in an algorithmic search of $ \sim 10^8 $ measurements of $ \sim 10^6 $ stars. The characteristic time scales are in the range $ 8.6 < t_0 < 62 $ days, where $ t_0 = R...
1994-07-05
2007-05-23
[ "astro-ph" ]
A. Udalski, M. Szymanski, K.Z. Stanek, J. Kaluzny, M. Kubiak, M. Mateo, W. Krzeminski, B. Paczynski, and R. Venkat
astro-ph/9407012
Fractal Cold Gas as Dark Matter in Galaxies and Clusters
The conjecture that dark matter in galaxies is mostly cold fractal gas is developed in the more general context of the thermodynamics of the ideal isothermal gas subject to gravitational instability. This simple gas model already contains the contrary ingredients able to prevent an asymptotic equilibrium: any growing g...
1994-07-05
2007-05-23
[ "astro-ph" ]
D. Pfenniger, F. Combes
astro-ph/9407013
News on Dark Matter in Galaxies and Clusters
Major progresses have been made this last year towards a better knowledge of the invisible mass. Michel Spiro will talk in details about the micro-lensing experiments and their promising results; the ROSAT satellite has provided extended X-ray maps of the hot gas, which traces dark matter in galaxy clusters: they revea...
1994-07-05
2007-05-23
[ "astro-ph" ]
F. Combes, D. Pfenniger
astro-ph/9407015
Surface Temperature of a Magnetized Neutron Star and Interpretation of the ROSAT Data. I. Dipolar Fields
We model the temperature distribution at the surface of a magnetized neutron star and study the effects on the observable X-ray spectra and light curves, taking fully into account gravitational lensing. Only dipolar fields are considered here. General features are studied and compared with the ROSAT data from the pulsa...
1994-07-05
2009-10-22
[ "astro-ph" ]
Dany Page
astro-ph/9407010
Are the Ogle Microlenses in the Galactic Bar?
The analysis of the first two years of OGLE data revealed 9 microlensing events of the galactic bulge stars, with the characteristic time scales in the range $ 8.6 < t_0 < 62 $ days, where $ t_0 = R_E / V $. The optical depth to microlensing is larger than $ ( 3.3 \pm 1.2 ) \times 10^{-6}$, in excess of current theoret...
1994-07-04
2008-12-18
[ "astro-ph" ]
B. Paczynski, K. Z. Stanek, A. Udalski, M. Szymanski, J. Kaluzny, M. Kubiak, M. Mateo, W. Krzeminski
astro-ph/9407011
Sizes of Voids as a test for Dark Matter Models
We use the void probability statistics to study the redshift-space galaxy distribution as described by a volume-limited subsample of the Perseus-Pisces survey. We compare the results with the same analysis realized on artificial samples, extracted from high-resolution N-body simulations by reproducing the observational...
1994-07-04
2009-10-22
[ "astro-ph" ]
S.Ghigna, S.Borgani, S.Bonometto, L.Guzzo, A.Klypin, J.R.Primack, R.Giovanelli, M.Haynes
astro-ph/9407009
Probable Gravitational Microlensing towards the Galatic Bulge
The MACHO project carries out regular photometric monitoring of millions of stars in the Magellanic Clouds and Galactic Bulge, to search for very rare gravitational microlensing events due to compact objects in the galactic halo and disk. A preliminary analysis of one field in the Galactic Bulge, containing {$\sim430,0...
1994-07-03
2009-10-22
[ "astro-ph" ]
C.Alcock, R.Allsman, T.Axelrod, D.Bennett, S.Chan, K.Cook, K.Freeman, K.Griest, S. Marshall, S.Perlmutter, B.Peterson, M.Pratt, P.Quinn, A.Rodgers, C.Stubbs, and W.Sutherland
astro-ph/9407008
ROSAT PSPC observation of the X-ray faint early-type galaxy NGC5866
We present the results of the analysis of the ROSAT PSPC pointed observation of the S0 galaxy NGC5866. Previous Einstein observations had revealed that this galaxy has a low X-ray to optical ratio Lx/Lb. Theoretical models of the X-ra emission of early-type galaxies had suggested that in objects of this kind the emissi...
1994-07-03
2011-05-23
[ "astro-ph" ]
S. Pellegrini
astro-ph/9407001
Gamma Line Radiation Emission from Stellar Winds in Orion Complex: A test for cosmic ray origin theory
We consider $\gamma$-ray emission from heavy nuclei that are accelerated in the shocks of stellar winds and are excited in interactions with the ambient matter in the Orion complex. We show that the recent detection of $\gamma$-ray lines in the Orion complex by COMPTEL telescope can be explained by such a scenario, ass...
1994-07-01
2007-05-23
[ "astro-ph" ]
Biman B. Nath and Peter L. Biermann
astro-ph/9407002
A ROSAT Hri Obsrevation of the Cooling Flow Cluster MS0839.9+2938
A ROSAT HRI observation of the cluster MS0839.9+2938 at z=0.194 is presented. It confirms the earlier suggestion, based on the detection of extended H$\alpha$ emission, that the inner regions of this cluster are dominated by a cooling flow. The surface brightness distribution within the cooling radius shows structures ...
1994-07-01
2007-05-23
[ "astro-ph" ]
R. Nesci, G.C. Perola and A. Wolter
astro-ph/9407003
The Ensemble Variability Properties of Faint QSOs
A refined sample of 64 variable objects with stellar image structure has been identified in SA 57 to $B \sim 22.5$, over a time baseline of 15 years, sampled at 11 distinct epochs. The photometric data typically have a root-mean-square error at $B = 22$ of only 0.05 mag. Thirty-five quasars in this field have already b...
1994-07-01
2009-10-22
[ "astro-ph" ]
D. Trevese, R.G. Kron, S.R. Majewski, M.A. Bershady, D.C. Koo
astro-ph/9407006
Big-Bang Nucleosynthesis and the Baryon Density of the Universe
Big-bang nucleosynthesis is one of the cornerstones of the standard cosmology. For almost thirty years its predictions have been used to test the big-bang model to within a fraction of a second of the bang. The concordance that exists between the predicted and observed abundances of D, $^3$He, $^4$He and $^7$Li provide...
1994-07-01
2009-10-22
[ "astro-ph" ]
Craig J Copi, David N. Schramm and Michael S. Turner
astro-ph/9407007
Cosmological Time Dilation in Gamma Ray Bursts?
Norris et al. (1994) report that the temporal structure of faint gamma ray bursts is longer than that of bright bursts, as expected for time dilation in the cosmological models of burst origin. I show that the observed trends can easily be produced by a burst luminosity function and thus may not result from cosmologica...
1994-07-01
2009-10-22
[ "astro-ph" ]
David Band
astro-ph/9407005
Models of Galaxies with Central Black Holes: Adiabatic Growth in Spherical Galaxies
We add black holes to nonrotating, spherical galaxy models, with the assumption that the black-hole growth is slow compared with the dynamical time but fast compared with the relaxation time. The outcome differs depending on whether the core of the initial galaxy does or does not resemble that of an isothermal sphere. ...
1994-07-01
2010-04-29
[ "astro-ph" ]
Gerald D. Quinlan, Lars Hernquist, and Steinn Sigurdsson
astro-ph/9407004
Mapping the Dark Matter in Clusters
Massive clusters of galaxies gravitationally shear the images of faint background galaxies. At large impact parameters the shear is weak, but can still be measured, to a reasonable degree of significance, as a statistical anisotropy of the faint galaxy images. We describe techniques for measuring the shear and discuss ...
1994-07-01
2007-05-23
[ "astro-ph" ]
Nick Kaiser, Gordon Squires, Greg Fahlman and David Woods
astro-ph/9406076
Gravitational Wave Induced Large-scale Polarization of \\Cosmic Microwave Background Radiation
We discuss the contribution of gravitational wave to the cosmic microwave background radiation (CMBR) anisotropy and polarization. It is found that the large-scale polarization of CMBR is less than 1\% for a standard recombination universe. The effect of matter reionization will enhance the CMBR polarization to a 10\% ...
1994-06-30
2009-10-22
[ "astro-ph", "gr-qc" ]
Ka Lok Ng and Kin-Wang Ng
astro-ph/9406074
Comment on The Preprint ``Neutrino Flavor Evolution Near A Supernova's Core'' (Astro-Ph 9405008) by J. Pantaleone
The revised version of the widely circulated preprint ``Neutrino Flavor Evolution Near A Supernova's Core'' by J. Pantaleone (astro-ph 9405008 on the Bulletin Board, Indiana University preprint IUHET-276) is wrong. It contains two errors which lead to incorrect conclusions regarding neutrino flavor transformation in th...
1994-06-29
2009-09-25
[ "astro-ph" ]
Yong-Zhong Qian and George M. Fuller
astro-ph/9406073
Neutrino-Neutrino Scattering and Matter-Enhanced Neutrino Flavor Transformation in Supernovae
We examine matter-enhanced neutrino flavor transformation ($\nu_{\tau(\mu)}\rightleftharpoons\nu_e$) in the region above the neutrino sphere in Type II supernovae. Our treatment explicitly includes contributions to the neutrino-propagation Hamiltonian from neutrino-neutrino forward scattering. A proper inclusion of the...
1994-06-29
2010-04-06
[ "astro-ph" ]
Yong-Zhong Qian and George M. Fuller
astro-ph/9406075
Testing Inflation with the Cosmic Background Radiation
In inflation cosmologies, cosmic structure develops through the gravitational instability of the inevitable quantum noise in primordial scalar fields. I show how the acceleration of the universe defines the shape of the primordial spectrum of gravitational metric and scalar field fluctuations. I assess how we can deter...
1994-06-29
2009-09-25
[ "astro-ph" ]
J. Richard Bond
astro-ph/9406071
The Nature versus Nurture of Anisotropies
With the rapidly growing number of cosmic microwave background measurements on various scales, there is real hope that the number of acceptable models for structure formation will be limited to a very few in the near future. Yet any given model can always be saved by introducing and tuning extraneous free parameters. T...
1994-06-28
2007-05-23
[ "astro-ph" ]
Wayne Hu
astro-ph/9406067
Beyond the Small-Angle Approximation For MBR Anisotropy from Seeds
In this paper we give a general expression for the energy shift of massless particles travelling through the gravitational field of an arbitrary matter distribution as calculated in the weak field limit in an asymptotically flat space-time. It is {\it not} assumed that matter is non-relativistic. We demonstrate the sur...
1994-06-27
2009-12-30
[ "astro-ph" ]
Albert Stebbins and Shoba Veeraraghavan
astro-ph/9406069
CBR Anisotropy in an Open Inflation, CDM Cosmogony
We compute the cosmic background radiation anisotropy, produced by energy-density fluctuations generated during an early epoch of inflation, in an open cosmological model based on the cold dark matter scenario. At $\Omega_0 \sim$ 0.3 -- 0.4, the COBE normalized open model appears to be consistent with most observations...
1994-06-27
2009-10-22
[ "astro-ph", "gr-qc", "hep-ph" ]
Marc Kamionkowski, Bharat Ratra, David N. Spergel, and Naoshi Sugiyama
astro-ph/9406068
Dynamics of Silent Universes
We investigate the local non--linear dynamics of irrotational dust with vanishing magnetic part of the Weyl tensor, $H_{ab}$. Once coded in the initial conditions, this dynamical restriction is respected by the relativistic evolution equations. Thus, the outcome of the latter are {\it exact solutions} for special initi...
1994-06-27
2009-10-22
[ "astro-ph" ]
M. Bruni, S. Matarrese and O. Pantano
astro-ph/9406070
Reverberation mapping of active galactic nuclei : The SOLA method for time-series inversion
In this paper a new method is presented to find the transfer function of the broad-line region in active galactic nuclei. The subtractive optimally localized averages (SOLA) method is a modified version of the Backus-Gilbert method and is presented as an alternative to the more often used maximum-entropy method. The SO...
1994-06-27
2015-06-24
[ "astro-ph", "comp-gas", "nlin.CG" ]
Frank P. Pijpers and Ignaz Wanders
astro-ph/9406066
The Dynamical Survival of Small-Scale Substructure in Relaxed Galaxy Clusters
We consider the dynamical evolution of small-scale substructure in clusters within two extreme alternate scenarios for their possible origin: 1) the accretion of groups (or small clusters) on quasi-radial orbits, and 2) the merger of clusters of similar masses, followed by the decoupling of their dense cores. Using sim...
1994-06-24
2009-10-22
[ "astro-ph" ]
Guillermo Gonz\'alez-Casado, Gary A. Mamon, and Eduard Salvador-Sol\'e
astro-ph/9406065
Capanic: A Parallel Tree N-Body Code for Inhomogeneous Clusters of Processors
We have implemented a parallel version of the Barnes-Hut 3-D N-body tree algorithm under PVM 3.2.5, adopting an SPMD paradigm. We parallelize the problem by decomposing the physical domain by means of the {\bf Orthogonal Recursive Bisection} oct-tree scheme suggested by Salmon (1991), but we modify the original hypercu...
1994-06-24
2007-05-23
[ "astro-ph" ]
V. Antonuccio-Delogu and U. Becciani
astro-ph/9406064
Relativistic Jets and the Fanaroff-Riley Classification of Radio Galaxies
Recently, Owen(1993) and Owen and Ledlow (1994) have shown that the dividing line between Fanaroff-Riley class~I and class~II Radio Sources is very sharp when the sources are represented as points in the radio-optical luminosity plane. It is shown that if one accepts the propositions that the sources in the vicinity of...
1994-06-23
2016-08-30
[ "astro-ph" ]
Geoffrey V. Bicknell
astro-ph/9406061
Gravitational Wave Signatures of Superdense Objects in a Nonsingular Solution of Gravity Theory
A massive gravitationally bound object with a radius $r \leq 2GM/c^2$, which occurs in the non-singular version of the nonsymmetric gravitational theory (NGT), replaces the black hole in Einstein gravity theory. This object is kept stable by the attractive and repulsive forces generated by NGT, as well as standard matt...
1994-06-22
2007-05-23
[ "astro-ph" ]
J. W. Moffat
astro-ph/9406063
Carbon Abundances in F and G Dwarfs
We have determined carbon abundances or upper limits from the forbidden [C I] line at 8727.13 A for 85 F and early G type main sequence stars, with metallicities ranging between [Fe/H] = -1.0 and [Fe/H] = +0.25. The [C I] line has not been previously used for a study of this size. We find that the C/Fe abundance ratio ...
1994-06-22
2007-05-23
[ "astro-ph" ]
Helena Andersson and Bengt Edvardsson
astro-ph/9406062
Blue Stragglers in Galactic Globular Clusters: Playing with Specific Quantities
We present preliminary results obtained from the comparison of the specific frequencies of Blue Straggler Stars (BSS) detected so far in a sample of 26 Galactic globular clusters. The number of BSS seems to increase almost linearly with increasing the amount of sampled light in loose clusters, while it drops abruptly f...
1994-06-22
2011-05-23
[ "astro-ph" ]
F.R. Ferraro, F. Fusi Pecci, M. Bellazzini
astro-ph/9406060
Quoting Experimental Information
There was a question raised at this meeting as to the best way to present the results of experiments measuring anisotropies in the CMB. Here we will make some simple comments about the 3 main competing methods and some suggestions. In particular we will give an over-simplified but hopefully useful method of comparing G...
1994-06-21
2007-05-23
[ "astro-ph" ]
Martin White and Douglas Scott
astro-ph/9406058
Dwarf Spheroidals and the Evolution of Not-Too-Old Population II Stars
Previous evolutionary computations concerning stars with masses in the range of the ``Red Giants Transition Phase'' are extended to lower metallicities. Clusters isochrones for two values of the metallicity Z (Z=10E-4, 4E-4) and for ages down to 1 billion years are presented, discussing selected evolutionary features c...
1994-06-21
2009-09-25
[ "astro-ph" ]
V.Castellani & S. Degl'Innocenti
astro-ph/9406057
Ubc/Laval 2.7-Meter Liquid Mirror Telescope
We report the successful development and operation of a large astronomical liquid-mirror telescope. Employing a rotating 2.7-meter diameter mirror with a surface of liquid mercury, the telescope images a half-degree diameter field centered at the zenith. Located near Vancouver, British Columbia, it is equipped with a l...
1994-06-21
2019-08-17
[ "astro-ph" ]
P.Hickson, E.F.Borra, R.Cabanac, R.Content, B.K.Gibson, G.A.H.Walker
astro-ph/9406059
Analytic Error Estimates
I present an analytic method for estimating the errors in fitting a distribution. A well-known theorem from statistics gives the minimum variance bound (MVB) for the uncertainty in estimating a set of parameters $\l_i$, when a distribution function $F(z;\l_1 ... \l_m)$ is fit to $N$ observations of the quantity(ies) $z...
1994-06-21
2009-10-22
[ "astro-ph" ]
Andrew Gould
astro-ph/9406054
Circumstellar Interaction in SN 1993J
The radio and X-ray observations of SN 1993J during the first year can be consistently explained as a result of interaction of the expanding ejecta with a circumstellar medium. The density of the circumstellar gas can be deduced from the free-free absorption of the radio emission and from the X-ray luminosity. During t...
1994-06-18
2007-05-23
[ "astro-ph" ]
C. Fransson, P. Lundqvist and R.A. Chevalier
astro-ph/9406055
Relativistic Radiative Transfer for Spherical Flows
We present a new complete set of Lagrangian relativistic hydrodynamical equations describing the transfer of energy and momentum between a standard fluid and a radiation fluid in a general non-stationary spherical flow. The new set of equations has been derived for a particular application to the study of the cosmologi...
1994-06-18
2010-04-06
[ "astro-ph" ]
Luciano Rezzolla, John C. Miller
astro-ph/9406056
Phenomenological Aspects of the Pre-Big-Bang Scenario in String Cosmology
I review various aspects of the pre-big-bang scenario and of its main open problems, with emphasis on the role played by the dilaton. Since the dilaton is a compelling consequence of string theory, tests of this scenario are direct tests of string theory and also, more generally, of Planck scale physics.
1994-06-18
2016-08-30
[ "astro-ph", "gr-qc", "hep-th" ]
M. Gasperini
astro-ph/9406053
Variable Smoothing Lengths and Energy Conservation in Smoothed Particle Hydrodynamics
We present a new formulation of the equations of motion used in smoothed particle hydrodynamics (SPH). The spatial resolution in SPH is determined by the smoothing length, $h$, and it has become common practice for each particle to be given its own adaptive smoothing length, $h_i$. Consequently, the dynamic range that ...
1994-06-17
2015-06-24
[ "astro-ph" ]
Richard P. Nelson and John C.B. Papaloizou
astro-ph/9406051
The gravitational deflection of light in MOND
The deflection angle $\Delta\phi$ of light rays by the gravitational field of a spherical system $M(r)$ is calculated using the MOdified Newtonian Dynamics (MOND). It is shown that $\Delta\phi$ with an impact parameter $r_0$ can be expressed by the measured rotation velocity $v(r)$ as $\Delta\phi(r_0)=2\int_{r_0}^{\i...
1994-06-17
2016-08-30
[ "astro-ph" ]
Q. Bo, X.P. Wu and Z.L. Zou
astro-ph/9406052
Mapping Cluster Mass Distributions via Gravitational Lensing of Background Galaxies
We present a new method for measuring the projected mass distributions of galaxy clusters. The gravitational amplification is measured by comparing the joint distribution in redshift and magnitude of galaxies behind the cluster with that of field galaxies. We show that the total amplification is directly related to the...
1994-06-17
2009-10-22
[ "astro-ph" ]
T.J. Broadhurst, A.N. Taylor and J.A. Peacock (Royal Observatory, Blackford Hill, Edinburgh, UK)
astro-ph/9406050
A Two-Fluid Approximation for Calculating the Cosmic Microwave Background Anisotropies
We present a simple, yet accurate approximation for calculating the cosmic microwave background anisotropy power spectrum in adiabatic models. It consists of solving for the evolution of a two-fluid model until the epoch of recombination and then integrating over the sources to obtain the CMB anisotropy power spectrum....
1994-06-17
2009-10-22
[ "astro-ph" ]
Uros Seljak
astro-ph/9406047
Statistical Constraints on the Inflation Effective Potential from the COBE DMR Results
We explore constraints on various forms for the effective potential during inflation based upon a statistical comparison between inflation-generated fluctuations in the cosmic microwave background temperature and the COBE DMR results. Fits to the first year 53 A + B x 90 A + B cross correlation function using an effect...
1994-06-16
2009-10-22
[ "astro-ph", "hep-ph" ]
Hannu Kurki-Suonio and Grant J. Mathews
astro-ph/9406049
The Optical Redshift Survey: Sample Selection and the Galaxy Distribution
This is the first in a series of papers describing the {\it Optical Redshift Survey} (ORS), a redshift survey of optically selected galaxies covering 98\% of the sky above $|b| = 20^\circ$ (8.09 ster). The survey is drawn from the UGC, ESO, and ESGC galaxy catalogues, and contains two sub-samples, one complete to a $B$...
1994-06-16
2009-10-22
[ "astro-ph" ]
B.X. Santiago, M.A. Strauss, O. Lahav, M. Davis, A. Dressler, J. Huchra
astro-ph/9406048
Lyman alpha absorption at low redshifts and hot gas in galactic haloes
Motivated by recent observation of Lanzetta et al. that most luminous galaxies at low redshifts produce $\lya$ absorption at impact parameter $l\lsim 160 \kpch$, we propose that these absorbers are clouds confined by the pressure of ambient hot gas in galactic haloes. We determine the properties of this hot gas and of ...
1994-06-16
2016-06-08
[ "astro-ph" ]
H.J. Mo
astro-ph/9406046
Polarization and Anisotropy of the Microwave Sky
We study the polarization-polarization and polarization-temperature correlations in standard adiabatic scenarios for structure formation. Temperature anisotropies due to gravitational potential wells and oscillations in the photon-baryon-electron fluid on the surface of last scattering are each associated with a correl...
1994-06-14
2009-10-22
[ "astro-ph", "hep-ph" ]
David Coulson, Robert G. Crittenden and Neil Turok
astro-ph/9406045
Stochastic Inflation: New Results
This is an old article which has never been posted for public use and which only appeard in a relatively hard-to-get Proceedings of the Sakharov Conference in Moscow (May, 1991). The subject of this article has received a lot of attention in last two years. Although we acknowledge that there has been a very big progres...
1994-06-14
2007-05-23
[ "astro-ph" ]
A.Mezhlumian and A.Starobinsky
astro-ph/9406043
The Galaxy Group/Cosmology Connections
\def\spose#1{\hbox to 0pt{#1\hss}} \def\lta{\mathrel{\spose{\lower 3pt\hbox{$\mathchar"218$}} \raise 2.0pt\hbox{$\mathchar"13C$}}} Groups of galaxies are highly linked to cosmology: 1) groups are tidally destroyed by the tidal field of the cluster they fall into; 2) spherical infall leads to the young cosmo-dynamical...
1994-06-14
2007-05-23
[ "astro-ph" ]
Gary A. Mamon (IAP)
astro-ph/9406044
Star Forming Galaxy Models: Blending Star Formation into TREESPH
We have incorporated star formation algorithms into a hybrid N-body/smoothed particle hydrodynamics code (TREESPH) in order to describe the star forming properties of disk galaxies over timescales of a few billion years. The models employ a Schmidt law of index $n\sim 1.5$ to calculate star formation rates, and explici...
1994-06-14
2007-05-23
[ "astro-ph" ]
Chris Mihos and Lars Hernquist
astro-ph/9406042
Femtolensing: Beyond the Semi-Classical Approximation
Femtolensing is a gravitational lensing effect in which the magnification is a function not only of the positions and sizes of the source and lens, but also of the wavelength of light. Femtolensing is the only known effect of $(10^{-13}-10^{-16} M_{\sun})$ dark-matter objects and may possibly be detectable in cosmologi...
1994-06-13
2009-10-22
[ "astro-ph" ]
A. Ulmer and J. Goodman
astro-ph/9406036
Determining Gravitational Masses of Galaxy Clusters With (1)Virial Equilibrium And (2)Arc-like Images
The mass derived from gravitational lensing reflects the total mass contained in the lensing system, independent of the specific matter contents and states. A comparison of the dynamical masses from hydrostatic equilibrium with the gravitational masses from arc-like images of background galaxies is made for four cluste...
1994-06-13
2009-10-22
[ "astro-ph" ]
Xiang-Ping Wu
astro-ph/9406037
VLBI Observations of a Complete Sample of Radio Galaxies. IV-The Radio Galaxies NGC2484, 3C109 and 3C382
We present here new VLBI observations of one FR-I radio galaxy (NGC2484) and two Broad Line FR-II radio galaxies (3C109 and 3C382). For 3C109 new VLA maps are also shown. These sources belong to a complete sample of radio galaxies under study for a better knowledge of their structures at parsec resolution. The parsec s...
1994-06-13
2009-10-22
[ "astro-ph" ]
G. Giovannini, L. Feretti, T.Venturi, L. Lara, J. Marcaide, M. Rioja, S. R. Spangler, A. E. Wehrle
astro-ph/9406040
Interpreting the candidate Galactic microlensing events
Four microlensing collaborations are presently searching for compact matter in the Galaxy and all have detected possible candidates. Using the detection efficiencies recently published by the MACHO and OGLE collaborations, we present Monte-Carlo calculations of the expected optical depth, rates and timescales, along th...
1994-06-13
2015-06-24
[ "astro-ph" ]
Eamonn J. Kerins
astro-ph/9406039
Solar Neutrinos: Sensitivity to Pre-Main Sequence Evolution and to the Depth of the Convective Zone
Predicted rates for solar neutrino experiments that are obtained with a modified stellar evolution code originally developed to study the advanced stages of stellar evolution are shown to be in agreement with other recently-calculated precise solar models to about 2% (0.2 SNU for the chlorine experiment). Different sce...
1994-06-13
2009-10-22
[ "astro-ph" ]
John N. Bahcall and Ami Glasner
astro-ph/9406038
Can Standard Cosmological Models Explain the Observed Abell Cluster Bulk Flow?
Lauer \& Postman (LP) observe that all Abell clusters with redshifts less than 15,000\kms\ appear to be participating in a bulk flow of 689 km s$^{-1}$ with respect to the Cosmic Microwave Background. We find this result difficult to reconcile with all popular models for large-scale structure formation that assume Gaus...
1994-06-13
2009-10-22
[ "astro-ph" ]
M.A. Strauss, R. Cen, J.P. Ostriker, T.R. Lauer, and M. Postman
astro-ph/9406041
Simulations of Relativistic Extragalactic Jets
We describe a method for the numerical solution of the relativistic Euler equations which we have found to be both robust and efficient, and which has enabled us to simulate relativistic jets. The technique employs a solver of the Godunov-type, with approximate solution of the local Riemann problems, applied to laborat...
1994-06-13
2007-05-23
[ "astro-ph" ]
G. Comer Duncan and Philip A. Hughes
astro-ph/9406033
Dynamical Model of Pulsar-Planet Systems
About two years ago, Wolszczan and Frail announced the detection of a possible planetary system consisting of two Earth-mass planets around a millisecond pulsar. It was pointed out shortly thereafter that the mutual gravitational interaction of the planets leads to predictable evolution of their orbits. Because millise...
1994-06-11
2007-05-23
[ "astro-ph" ]
Renu Malhotra
astro-ph/9406034
Simulations of Clusters of Galaxies
The degree of complexity and, to a somewhat lesser degree, realism in simulations has advanced rapidly in the past few years. The simplest approach - modeling a cluster as collisionless dark matter and collisonal, non--radiative gas is now fairly well established. One of the most fruitful results of this approach is th...
1994-06-11
2007-05-23
[ "astro-ph" ]
August E. Evrard
astro-ph/9406035
Viscosity Prescriptions in Accretion Disks with Shock Waves
We study the evolution of viscous, isothermal, rotating, thin, axisymmetric accretion disks around a compact object using Smoothed Particle Hydrodynamics. We emphasize the effects of different choices of viscosity prescriptions on the evolution of angular momentum as well as other physical quantities of the disk. We sh...
1994-06-11
2008-02-03
[ "astro-ph" ]
Sandip K. Chakrabarti and Diego Molteni
astro-ph/9406032
Hydrodynamics of Binary Coalescence. II. Polytropes with Gamma=5/3
We present a new numerical study of the equilibrium and stability properties of close binary systems using the smoothed-particle hydrodynamics (SPH) technique. We adopt a simple polytropic equation of state $p=K\rho^\gam$ with $\gam=5/3$ and $K=\,$constant within each star, applicable to low-mass degenerate dwarfs as w...
1994-06-10
2009-10-22
[ "astro-ph" ]
F. A. Rasio and S. L. Shapiro
astro-ph/9406031
Implications of Neutrino Balls as the Source of Gamma-Ray Bursts
(To appear in the Astrophysical Journal) Holdom and Malaney (1994) have suggested a mechanism for gamma-ray bursts which requires that stars be captured by a neutrino ball. Neutrino balls would be, for the most part, denser than main sequence stars, but their density would decrease as their mass increased. We show that...
1994-06-10
2009-10-22
[ "astro-ph" ]
D.Syer, Cita
astro-ph/9406027
New Automatic Identification Technique for OB Associations in Unresolved Galaxies
We present a new automatic technique based on Principal Component Analysis and Cluster Analysis, with the aim of its application to the identification of those clumps in unresolved galaxies which likely represent regions of star formation. We test the method by applying it to the galaxy M~31, for which there are alread...
1994-06-09
2011-05-23
[ "astro-ph" ]
S. Adanti, P. Battinelli, R. Capuzzo--Dolcetta and P.W. Hodge
astro-ph/9406030
Evidence from Gravitational Lensing for a Non-Thermal Pressure Support in the Cluster of Galaxies A2218
The central mass distribution of clusters of galaxies can be inferred from gravitationally lensed arcs with known redshifts. For the Abell cluster 2218, this method yields a core mass which is larger by a factor of $2.5 \pm 0.5$ than the value deduced from X-ray observations, under the assumptions that the gas is suppo...
1994-06-09
2009-10-22
[ "astro-ph" ]
Abraham Loeb and Shude Mao
astro-ph/9406029
The Mass Function of Cosmic Structures with Non-Spherical Collapse
Non-spherical dynamical approximations and models for the gravitational collapse are used to extend the well-known Press \& Schechter (PS) approach, in order to determine analytical expressions for the mass function of cosmic structures. The problem is rigorously set up by considering the intrinsic Lagrangian nature of...
1994-06-09
2009-09-25
[ "astro-ph" ]
Pierluigi Monaco
astro-ph/9406028
Black Holes from Blue Spectra
Blue primordial power spectra with a spectral index $n>1$ can lead to a significant production of primordial black holes in the very early Universe. The evaporation of these objects leads to a number of observational consequences and a model independent upper limit of $n \approx 1.4$. In some cases this limit is streng...
1994-06-09
2007-05-23
[ "astro-ph", "gr-qc" ]
James E. Lidsey, B.J. Carr & J.H. Gilbert
astro-ph/9406024
Stability of Fireballs and $\gamma$-Ray Bursts
Fireballs are an essential part of any cosmological $\gamma$-ray burst. We drive here a stability criterion for fireballs and show that fireballs are Rayleigh-Taylor unstable in any region in which the entropy decreases outward. The instability begins to operate when the fireball becomes matter dominated. Among the pos...
1994-06-08
2009-10-22
[ "astro-ph" ]
Eli Waxman and Tsvi Piran
astro-ph/9406026
The Imprint of $\Omega$ on the Cosmic Microwave Background
We investigate the dependence of large angular scale cosmic microwave background anisotropies on various initial conditions, including both adiabatic and isocurvature perturbations and the initial power law index $n$, in a variety of low-$\Omega$ cosmological models. Cosmological constant- dominated flat models and inf...
1994-06-08
2009-10-22
[ "astro-ph" ]
Naoshi Sugiyama and Joseph Silk
astro-ph/9406022
Secular Evolution of the Eccentricity in the PSR 1620-26 Triple System
A simple analytic calculation is presented for the secular evolution of the eccentricities in a hierarchical triple system such as the one containing the millisecond pulsar PSR 1620-26 in M4. If the second companion of PSR 1620-26 is of stellar mass ($m_2\ga0.1\,M_\odot$), an eccentricity as large as that observed toda...
1994-06-08
2007-05-23
[ "astro-ph" ]
F. A. Rasio
astro-ph/9406025
Integrated photometric properties of open clusters
Galactic open clusters provide an abundant sample of stellar aggregates of various sizes, ages and metal abundances, apt to constitute a template for comparison with star systems in other galaxies. In this paper we present and discuss a standard methodology to synthesize {\sl U,B,V} fluxes and colours, and apply it to ...
1994-06-08
2011-05-23
[ "astro-ph" ]
P. Battinelli, A. Brandimarti, and R. Capuzzo--Dolcetta
astro-ph/9406023
Environmental Effects on Local Active Galactic Nuclei
Using an extensive sample of nearby galaxies (the Nearby Galaxies Catalog, by Tully), we investigate the environment of the galaxies hosting low-luminosity AGNs (Seyferts and LINERs). We define the local galaxy density, adopting a new correction for the incompleteness of the galaxy sample at large distances. We conside...
1994-06-08
2009-10-22
[ "astro-ph" ]
Pierluigi Monaco, Giuliano Giuricin, Fabio Mardirossian, Marino Mezzetti
astro-ph/9406021
$\gamma$-Ray Pulsars: Emission Zones and Viewing Geometries, A Computer Animation
The computer animation illustrates the geometries described in a paper by the same authors. The preprint is available as number 9401045. The opening scene shows dipole field lines emanating from the polar caps of a rotating neutron star. The dipole axis is inclined along the green rods. The field lines shown are define...
1994-06-08
2007-05-23
[ "astro-ph" ]
I.-A. Yadigaroglu and Roger W. Romani
astro-ph/9406020
Power Spectrum of Cosmic String Perturbations on the Microwave Background
I review recent progress towards a detailed understanding of the power spectrum of cosmic string perturbations induced on the Microwave Background (CMB). The use of a simple analytic model allows to include important effects that have not been included in previous studies. These effects are potential fluctuations on th...
1994-06-07
2007-05-23
[ "astro-ph", "hep-ph" ]
Leandros Perivolaropoulos
astro-ph/9406016
Lagrangian Dynamics in Non-Flat Universes and Non-Linear Gravitational Evolution
We present a new formalism which allows to derive the general Lagrangian dynamical equations for the motion of gravitating particles in a non--flat Friedmann universe with arbitrary density parameter $\Omega$ and no cosmological constant. We treat the set of particles as a Newtonian collisionless fluid. The non--linear...
1994-06-07
2015-06-24
[ "astro-ph" ]
Paolo Catelan (Department of Astrophysics, Oxford)
astro-ph/9406018
Abundances of four very metal-poor stars of the BPS survey
High resolution CASPEC and EMMI spectra (R$\approx$10$^4$) of the faint metal- deficient candidates CS 22891--209, CS 22897--8, CS 22948--66 and CS 22968--14 taken from the survey of Beers, Preston and Shectman (1985, BPS) are analyzed for abundances. The fine analysis with LTE model atmospheres gives an iron metallici...
1994-06-07
2007-05-23
[ "astro-ph" ]
Francesca Primas, Paolo Molaro and Fiorella Castelli
astro-ph/9406017
Constraints to the Masses of Brown Dwarf Candidates from the Lithium Test
We present intermediate dispersion (0.7-2.2 \AA ~pix$^{-1}$) optical spectroscopic observations aimed at applying the ``Lithium Test'' to a sample of ten brown dwarf candidates located in the general field, two in young open clusters, and two in close binaries. We find evidence for strong Li depletion in all of them, a...
1994-06-07
2015-06-24
[ "astro-ph" ]
E.L. Martin, R. Rebolo, A. Magazzu
astro-ph/9406019
M Dwarfs, Microlensing, and the Mass Budget of the Galaxy
We show that faint red stars do not contribute significantly to the mass budget of the Galaxy or to microlensing statistics. Our results are obtained by analyzing two long exposures of a high-latitude field taken with the Wide Field Camera on the newly repaired {\it Hubble Space Telescope}. Stars are easily distinguish...
1994-06-07
2009-10-22
[ "astro-ph" ]
John N. Bahcall, Chris Flynn, Andrew Gould, and Sofia Kirhakos
astro-ph/9406014
Non--Gaussian Effects in the Cosmic Microwave Background from Inflation
The presence of non--Gaussian features in the Cosmic Microwave Background (CMB) radiation maps represents one of the most long--awaited clues in the search for the actual structure of the primordial radiation, still needing confirmation. These features could shed some light on the non trivial task of distinguishing the...
1994-06-06
2009-10-22
[ "astro-ph" ]
Alejandro Gangui
astro-ph/9406012
New Evidence for the Cosmological Origin of Gama-Ray Bursts
We compare the burst distribution of the new (2B) BATSE catalogue to a cosmological distribution. We find that the distribution is insensitive to cosmological parameters such as Omega and Lambda and to the width of the bursts luminosity function. The maximal red shift of the long bursts is ~2.1 (assuming no evolution) ...
1994-06-06
2009-09-25
[ "astro-ph" ]
Ehud Cohen, Tsafrir Kolatt and Tsvi Piran (Racah Institute for Physics, The Hebrew University, Jerusalem, Israel)
astro-ph/9406015
The Flattened Dark Halo of Polar Ring Galaxy NGC 4650A: A Conspiracy of Shapes?
Kinematics and photometry of the polar ring galaxy NGC 4650A, including new observations of the rotation and velocity dispersion of its central stellar disk, are used to infer the presence of a dark matter halo and to measure its shape. Fits to the observed disk and polar ring rotation curves from detailed mass and pho...
1994-06-06
2009-10-22
[ "astro-ph" ]
Penny D. Sackett, Hans-Walter Rix, Brian J. Jarvis, and Kenneth C. Freeman
astro-ph/9406013
Perturbative Lagrangian Approach to Gravitational Instability
This paper deals with the time evolution in the matter era of perturbations in Friedman-Lemaitre models with arbitrary density parameter $\Omega$, with either a zero cosmological constant, $\Lambda = 0$, or with a non-zero cosmological constant in a spatially flat Universe. Unlike the classical Eulerian approach where ...
1994-06-06
2011-05-23
[ "astro-ph" ]
F.R. Bouchet, S. Colombi, E. Hivon, R. Juszkiewicz
astro-ph/9406010
Introduction: Why and How to Probe the Zone of Avoidance ?
The motivation and major ways for probing the Zone of Avoidance (ZOA) are reviewed. Galaxies hidden behind the ZOA may have important implications for the internal dynamics of the Local Group, for the origin of its motion relative to the Microwave Background, and for the connectivity of the large scale structure. Curre...
1994-06-05
2007-05-23
[ "astro-ph" ]
Ofer Lahav
astro-ph/9406011
Wiener Reconstruction of All-Sky Spherical Harmonic Maps of the Large Scale Structure
A statistical method for reconstructing large scale structure behind the Zone of Avoidance is presented. It also corrects for shot-noise and for redshift distortion in galaxy surveys. The galaxy distribution is expanded in an orthogonal set of spherical harmonics. We show that in the framework of Bayesian statistics an...
1994-06-05
2007-05-23
[ "astro-ph" ]
Ofer Lahav
astro-ph/9406009
Wiener Reconstruction of Density, Velocity, and Potential Fields from All-Sky Galaxy Redshift Surveys
We present a new method for recovering the cosmological density, velocity, and potential fields from all-sky redshift catalogues. The method is based on an expansion of the fields in orthogonal radial (Bessel) and angular (spherical harmonic) functions. In this coordinate system, peculiar velocities introduce a couplin...
1994-06-03
2015-06-24
[ "astro-ph" ]
Karl Fisher, Ofer Lahav, Yehuda Hoffman, Donald Lynden-Bell, and Saleem Zaroubi
astro-ph/9406008
Cosmological Simulations of Galaxy Formation Including Hydrodynamics (hyper-abridged)
The formation of galaxies in hierarchical cosmogonies is studied using high resolution N-body plus SPH hydrodynamics simulations. The collapse of structure is followed self-consistently from Mpc scale filamentary structures to kpc scale galactic objects. The characteristics and formation processes of the galaxy like ob...
1994-06-02
2007-05-23
[ "astro-ph" ]
F J Summers
astro-ph/9406007
On the nature of gamma-ray burst time dilations
The recent discovery that faint gamma-ray bursts are stretched in time relative to bright ones has been interpreted as support for cosmological distances: faint bursts have their durations redshifted relative to bright ones. It was pointed out, however, that the relative time stretching can also be produced by an intri...
1994-06-02
2009-10-22
[ "astro-ph" ]
Ralph A.M.J. Wijers and Bohdan Paczy\'nski
astro-ph/9406006
On the Nature of Photospheric Oscillations in Strong X--Ray Bursts
A possible sound origin for the photospheric oscillations in the X--ray bursting sources 1608-522 and 2127+119 is suggested. It is shown that standing sound waves in an expanding spherical envelope can have periods very close to the observed ones. The quite large ratio, $\sim$ 10, of the periods in the two sources is e...
1994-06-02
2009-10-22
[ "astro-ph" ]
Iosif Lapidus, Luciano Nobili and Roberto Turolla
astro-ph/9406005
Effects of Photoionization on Galaxy Formation
We investigate the effects of the observed UV background radiation on galaxy formation. Photoionization by UV radiation decreases the cooling rate of the gas in halos, so that objects with only large density contrasts can self-shield against the background radiation, thereby allowing the shielded neutral cores to cool ...
1994-06-02
2009-10-22
[ "astro-ph" ]
Masashi Chiba and Biman B. Nath
astro-ph/9406004
Modeling the Radial Distribution of Blue Stragglers in M3
Recent surveys of the blue straggler (BS) population in the galactic globular cluster M3 (NGC 5272) give the first complete characterization of the number density of BSs as a function of radius over an entire globular cluster. The BSs in M3 are overabundant at large radii, and significantly underabundant at intermediat...
1994-06-01
2009-10-22
[ "astro-ph" ]
Steinn Sigurdsson, Melvyn B. Davies and Michael Bolte