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/9408028
Cold Dark Matter I: The Formation of Dark Halos
We use numerical simulations of critically-closed cold dark matter (CDM) models to study the effects of numerical resolution on observable quantities. We study simulations with up to $256^3$ particles using the particle-mesh (PM) method and with up to $144^3$ particles using the adaptive particle-particle --particle-me...
1994-08-09
2009-10-22
[ "astro-ph" ]
James M. Gelb and Edmund Bertschinger
astro-ph/9408029
Cold Dark Matter II: Spatial and Velocity Statistics
We examine high-resolution gravitational N-body simulations of the $\Omega=1$ cold dark matter (CDM) model in order to determine whether there is any normalization of the initial density fluctuation spectrum that yields acceptable results for galaxy clustering and velocities. Dense dark matter halos in the evolved mass...
1994-08-09
2009-10-22
[ "astro-ph" ]
James M. Gelb and Edmund Bertschinger
astro-ph/9408027
Tomography of Collisionless Stellar Systems
In this paper the concept of tomography of a collisionless stellar system of general shape is introduced, and a generalization of the Projected Virial Theorem is obtained. Applying the tomographic procedure we then derive a new family of virial equations which coincides with the already known ones for spherically symme...
1994-08-09
2009-10-22
[ "astro-ph" ]
L. Ciotti (Osservatorio Astronomico di Bologna)
astro-ph/9408026
The Optical Gravitational Lensing Experiment. the Early Warning System
The discoveries of 17 microlensing event candidates have been reported over the last year by three teams conducting unprecedented mass photometric searches in the direction of the Galactic bulge and the Magellanic Clouds. These include 10 events found by the OGLE collaboration, 5 by the MACHO team and 2 by the EROS tea...
1994-08-08
2009-09-25
[ "astro-ph" ]
A. Udalski, M. Szymanski, J. Kaluzny, M. Kubiak, M. Mateo, W. Krzeminski, and B.Paczynski
astro-ph/9408024
Symplectic Integration without Roundoff Error
Most numerical integration algorithms are not designed specifically for Hamiltonian systems and do not respect their characteristic properties, which include the preservation of phase space volume with time. This can lead to spurious damping or excitation. Methods that do preserve all the Hamiltonian properties, i.e., ...
1994-08-08
2015-06-24
[ "astro-ph", "chao-dyn", "comp-gas", "nlin.CD", "nlin.CG", "nlin.SI", "solv-int" ]
David JD Earn
astro-ph/9408025
Finite Disks with Power-Law Potentials
We describe a family of circular, and elliptical, finite disks with a disk potential that is a power of the radius. These are all flattened ellipsoids, obtained by squashing finite spheres with a power-law density distribution, and cutoff at some radius Ro. First we discuss circular disks whose circular rotation speed ...
1994-08-08
2009-10-22
[ "astro-ph" ]
R. Brada and M. Milgrom
astro-ph/9408023
Big Bang Nucleosynthesis Constraints and Light Element Abundance Estimates
To elucidate the significance of the effect of systematic uncertainties in light element abundance estimates on cosmological bounds derivable from Big Bang Nucleosynthesis (BBN) we present tables giving bounds on $\Omega_{baryon}$ and $N_{\nu}$ as one changes the limits on primordial \he and $^7$Li. This allows us to d...
1994-08-07
2009-10-22
[ "astro-ph", "hep-ph" ]
Lawrence M. Krauss and Peter J. Kernan
astro-ph/9408022
The Orientation of Spin Vectors of Galaxies in the Ursa Major Filament
Spin vectors of 60 galaxies in the ``Ursa Major Filament'' are obtained from CCD images and spectroscopic determinations of the directions of rotation. These data are used to remove the four-fold degeneracy introduced by the project ed images of galaxies, making possible the complete reconstruction of the galaxy spin v...
1994-08-06
2009-10-22
[ "astro-ph" ]
Cheongho Han, et al
astro-ph/9408019
Hierarchical Pancaking: Why the Zel'dovich Approximation Describes Coherent Large-Scale Structure in N-Body Simulations of Gravitational Clustering
To explain the rich structure of voids, clusters, sheets, and filaments apparent in the Universe, we present evidence for the convergence of the two classic approaches to gravitational clustering, the ``pancake'' and ``hierarchical'' pictures. We compare these two models by looking at agreement between individual struc...
1994-08-05
2015-06-24
[ "astro-ph", "gr-qc" ]
Jennifer L. Pauls and Adrian L. Melott
astro-ph/9408018
Velocity Fields in Non--Gaussian Cold Dark Matter Models
We analyse the large--scale velocity field obtained by N--body simulations of cold dark matter (CDM) models with non--Gaussian primordial density fluctuations, considering models with both positive and negative primordial skewness in the density fluctuation distribution. We study the velocity probability distribution a...
1994-08-05
2015-06-24
[ "astro-ph" ]
F. Lucchin, S. Matarrese, A. Messina, L. Moscardini and G. Tormen
astro-ph/9408020
Are BL Lacertae Objects Beamed QSO Remnants?
This paper considers the hypothesis that BL Lacertae objects (BLLs) are the beamed remnants of Quasi Stellar Objects. The hypothesis explains why BLLs do not undergo the strong evolution seen in other active galactic nuclei since it naturally predicts that the space density of BLLs should increase with cosmic time, as ...
1994-08-05
2007-05-23
[ "astro-ph" ]
E.F. Borra
astro-ph/9408021
BIMA observations of possible microwave background sources
We present sensitive upper limits on the 90 GHz flux of known radio and infrared sources in regions associated with possible cosmic microwave background fluctuations at 0.5--1 degree scales. Specifically we look at the MAX GUM region and the region of strongest fluctuation in the MSAM scan. None of the known sources ca...
1994-08-05
2007-05-23
[ "astro-ph" ]
Lawrence M. Chernin & Douglas Scott
astro-ph/9408017
Evolution of the Potential in Cosmological Gravitational Clustering
In recent years there has been a developing realization that the interesting large--scale structure of voids, ``pancakes", and filaments in the Universe is a consequence of the efficacy of an approximation scheme for cosmological gravitation clustering proposal by Zel'dovich in 1970. However, this scheme was only suppo...
1994-08-04
2009-09-25
[ "astro-ph", "gr-qc" ]
Adrian L. Melott and Jennifer L. Pauls (Department of Physics and Astronomy, University of Kansas)
astro-ph/9408016
The Andante Regime of Scalar Field Dynamics
The andante regime of scalar field dynamics in the chaotic inflationary Universe is defined as the epoch when the field is rolling moderately slowly down its interaction potential, but at such a rate that first-order corrections to the slow-roll approximation become important. These conditions should apply towards the ...
1994-08-04
2009-10-22
[ "astro-ph" ]
James E. Lidsey and I. Waga
astro-ph/9408013
Gamma-Rays from the Funnels of Thick Accretion Disks Around Active Galactic Nuclei
We analyse the propagation of particles in the narrow funnel of a thick accretion disk. It is assumed that: (1) the funnel walls emit black body radiation with temperature decreasing outwards; (2) the magnetic and electric fields are longitudinal in the funnel. Such a scenario is consistent with models in which a large...
1994-08-04
2007-05-23
[ "astro-ph" ]
W. Bednarek and J.G. Kirk
astro-ph/9408015
Formalising the Slow-Roll Approximation in Inflation
The meaning of the inflationary slow-roll approximation is formalised. Comparisons are made between an approach based on the Hamilton-Jacobi equations, governing the evolution of the Hubble parameter, and the usual scenario based on the evolution of the potential energy density. The vital role of the inflationary attra...
1994-08-04
2009-10-22
[ "astro-ph" ]
Andrew R. Liddle, Paul Parsons and John D. Barrow
astro-ph/9408014
Evidences of Secular Dynamical Evolution in Disk Galaxies
After a recall of fundamental concepts used in galactic dynamics, we review observational facts as well as results of orbit theory and numerical simulations which suggest long-term evolution of galaxies. Dynamical interactions between galaxy constituents (bulges, disks, bars, haloes, dark matter) are discussed and effe...
1994-08-04
2007-05-23
[ "astro-ph" ]
Louis Martinet
astro-ph/9408010
The Reliability of X-ray Constraints of Intrinsic Cluster Shapes
Using the simulation of Katz & White we have tested the viability of X-ray analysis for constraining the intrinsic shapes of clusters of galaxies considering the effects of both substructure and steep temperature gradients. We restrict analysis to aggregate cluster shapes on scales of $r\sim 1-2$ Mpc to reduce our sens...
1994-08-03
2009-10-22
[ "astro-ph" ]
D. A. Buote and J. C. Tsai
astro-ph/9408011
The Near-Infrared Structure and Spectra of the Bipolar Nebulae M 2--9 and Afgl 2688: The Role of UV-Pumping and Shocks in Molecular Hydrogen Excitation
High-resolution near-infrared images and moderate resolution spectra were obtained of the bipolar nebulae M~2--9 and AFGL 2688. The ability to spatially and spectrally resolve the various components of the nebulae has proved to be important in determining their physical structure and characteristics. In M~2--9, the lob...
1994-08-03
2009-10-22
[ "astro-ph" ]
Joseph L. Hora and William B. Latter
astro-ph/9408012
Cosmic Ray Hydrodynamics at Shock Fronts
When a magnetised, thermal plasma containing a shock wave efficiently accelerates Cosmic Rays (CR) a reaction is exerted on the fluid structure. The simplest description of this process involves three conservation equations for the background fluid, with the CR pressure gradient included as an extra force, plus a hydro...
1994-08-03
2007-05-23
[ "astro-ph" ]
P. Duffy, L.O'C. Drury and H.J.Voelk
astro-ph/9408009
The Width of the Gamma-ray Burst Luminosity Function
We examine the width of the gamma-ray burst (GRB) luminosity function through the distribution of GRB peak count rates, C$_{\rm{peak}}$, as detected by BATSE (\cite{batse:93}). In the context of galactic corona spatial distribution models, we attempt to place constraints on the characteristic width of the luminosity fu...
1994-08-02
2009-10-22
[ "astro-ph" ]
Andrew Ulmer and Ralph A.M.J. Wijers
astro-ph/9408005
The Difference between Radio-Loud and Radio-Quiet Active Galaxies
The recent development of unified theories of active galactic nuclei (AGN) has indicated that there are two physically distinct classes of these objects - radio-loud and radio-quiet. The primary observational distinctions between the two types are: (1) The radio-loud objects produce large scale radio jets and lobes, wi...
1994-08-02
2016-08-30
[ "astro-ph" ]
Andrew S. Wilson and Edward J. M. Colbert
astro-ph/9408008
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...
1994-08-02
2007-05-23
[ "astro-ph" ]
Ralph A.M.J. Wijers and Bohdan Paczy\'nski
astro-ph/9408007
Light Element Abundance Inhomogeneities in Globular Clusters: Probing Star Formation and Evolution in the Early Milky Way
Abundance patterns of the elements C, N, and O are sensitive probes of stellar nucleosynthesis processes and, in addition, O abundances are an important input for stellar age determinations. Understanding the nature of the observed distribution of these elements is key to constraining protogalactic star formation histo...
1994-08-02
2015-06-24
[ "astro-ph" ]
M. M. Briley, R. A. Bell, J. E. Hesser, and G. H. Smith
astro-ph/9408004
Self-Lensing By A Stellar Disk
I derive a general expression for the optical depth $\tau$ for gravitational lensing of stars in a disk by Massive Compact Objects (Machos) in the same disk. For the more restricted case where the disk is self-gravitating and the stars and Machos have the same distribution function, I find $\tau = 2\VEV{v^2}/c^2\sec^2 ...
1994-08-01
2009-10-22
[ "astro-ph" ]
Andrew Gould
astro-ph/9408001
Polarization-Temperature Correlations in the Microwave Background
The polarization of the CMB offers a potentially valuable probe of the physics of the early universe, specifically of the velocity of the photon-baryon fluid on the last scattering surface. Here we discuss qualitatively the correlations that arise between the temperature anisotropies and polarization of the CMB and how...
1994-08-01
2007-05-23
[ "astro-ph" ]
Robert Crittenden
astro-ph/9408002
Dark Matter in the Light of COBE
The observations of all three COBE instruments are examined for the effects of dark matter. The anisotropy measured by the DMR, and especially the degree-scale ground- and balloon-based experiments, is only compatible with large-scale structure formation by gravity if the Universe is dominated by non-baryonic dark matt...
1994-08-01
2007-05-23
[ "astro-ph" ]
Edward L. Wright
astro-ph/9408006
Response to Comments on "Neutrino Flavor Evolution Near a Supernova's Core"
In a recent paper I concluded that the neutrino background is important for calculating neutrino flavor evolution in supernovae, and including it weakens the connection between r-process nucleosynthesis and cosmologically relevant neutrino masses. Comments on this paper have been posted to this bulletin board; one by J...
1994-08-01
2007-05-23
[ "astro-ph", "hep-ph" ]
J. Pantaleone
astro-ph/9408003
Comparison of Spectral Index Determinations
The index $n$ of a power law power spectrum of primordial density fluctuations, $P(k) \propto k^n$, has been estimated using many different techniques. The most precise compare the COBE DMR large angular scale $\Delta T$ to the amplitude of the large scale structure, but these are also the most model-dependent. The COB...
1994-08-01
2007-05-23
[ "astro-ph" ]
Edward L. Wright
astro-ph/9407100
Estimation of Peculiar Velocity from the Inverse Tully-Fisher Relation
We present a method for deriving a smoothed estimate of the peculiar velocity field of a set of galaxies with measured circular velocities $\eta\equiv {\rm log} \Delta v$ and apparent magnitudes $m$. The method is based on minimizing the scatter of a linear inverse Tully-Fisher relation $\eta= \eta(M)$ where the absolu...
1994-07-30
2015-06-24
[ "astro-ph" ]
Adi Nusser and Marc Davis
astro-ph/9407099
Implications of a High Population II B/Be Ratio
The observed B/Be ratio in extreme Pop II stars has been interpreted as evidence of Be and B synthesis by early galactic cosmic rays. However, a recent reanalysis of the boron abundance in the Pop II halo star HD140283 suggests that B/H may be larger than previously reported, by as much as a factor of 4. This would yie...
1994-07-29
2009-09-25
[ "astro-ph" ]
B. Fields, K. Olive, and D. Schramm
astro-ph/9407098
The Distances to Five Type~II Supernovae Using the Expanding Photosphere Method and the Value of $H_0$
We have used observations gathered at CTIO to measure distances by the Expanding Photosphere Method (EPM) to 5 Type II supernovae. These supernovae lie at redshifts from cz = 1100 km/s to z = 5500 km/s, and increase to 18 the number of distances measured using EPM. We compare distances derived to 11 Type II supernovae ...
1994-07-29
2007-05-23
[ "astro-ph" ]
Brian P. Schmidt Robert P. Kirshner, Ronald G. Eastman, Mark M. Phillips, Nicholas B. Suntzeff, Mario Hamuy, Jose Maza, and Roberto Aviles
astro-ph/9407097
SN~1991T: Reflections of Past Glory
We have obtained photometry and spectra of SN~1991T which extend more than 1000 days past maximum light, by far the longest a SN~Ia has been followed. Although SN~1991T exhibited nearly normal photometric behavior in the first 400 days following maximum, by 600 days its decline had slowed, and by 950~days the supernova...
1994-07-29
2009-10-22
[ "astro-ph" ]
Brian P. Schmidt, Robert P. Kirshner, Bruno Leibundgut, Lisa A. Wells, Alain C. Porter, Pilar Ruiz-Lapuente, Peter Challis and Alexei V. Filippenko
astro-ph/9407096
Gravitational Microlensing by the Globular Cluster Stars
The microlensing of background stars by compact objects in globular clusters is analyzed. The main strength of the proposed search is the direct relationship between the lens mass and the time scale of the microlensing event. The main problem is the low overall rate of expected events which implies that a ground based ...
1994-07-29
2007-05-23
[ "astro-ph" ]
Bohdan Paczynski
astro-ph/9407095
Kurtosis of Large-Scale Cosmic Fields
An attractive and simple hypothesis for the formation of large-scale structure is that it developed by gravitational instability from primordial fluctuations with an initially Gaussian probability distribution. Non-linear gravitational evolution drives the distribution away from the Gaussian form, generating measurable...
1994-07-29
2015-06-24
[ "astro-ph" ]
Ewa Luiza Lokas, Roman Juszkiewicz, David Weinberg, and Francois Bouchet
astro-ph/9407094
9 Aurigae: Strong Evidence for Non-Radial Pulsations
We present further photometric observations of the unusual F0 V star 9 Aurigae and present evidence that this star's radial velocity, spectroscopic line widths and line depths are also variable with the same frequencies as the photometric data ($f_1 \approx 0.795$ and $f_2 \approx 0.345$ d$^{-1}$). The phases of these ...
1994-07-29
2015-06-24
[ "astro-ph" ]
Kevin Krisciunas, Roger F. Griffin, Edward F. Guinan, Kenneth D. Luedeke, and George P. McCook
astro-ph/9407091
Cosmological Parameters from Angular Correlations between Qsos and Galaxies
The angular two-point correlation function between background QSOs and foreground galaxies induced by gravitational lensing is derived. It is shown that the shape of this correlation function depends sensitively on the spectrum of the density fluctuations in the Universe, thus providing a possibility to distinguish bet...
1994-07-28
2007-05-23
[ "astro-ph" ]
Matthias Bartelmann
astro-ph/9407093
Anisotropies in the Cosmic Microwave Background: An Analytic Approach
We introduce a simple yet powerful {\it analytic} method which obtains the structure of cosmic microwave background anisotropies to better than 5-10\% in temperature fluctuations on {\it all} scales. It is applicable to {\it any} model in which the potential fluctuations at recombination are both linear and known. More...
1994-07-28
2009-07-17
[ "astro-ph" ]
Wayne Hu and Naoshi Sugiyama
astro-ph/9407092
The Discovery of 8.7s Pulsations from the Ultrasoft X-Ray Source 4u0142+614
We discovered a periodicity at about 8.7s from the X--ray sources 4U0142+61, previously considered a possible black hole candidate on the basis of its ultrasoft spectrum. The pulsations are visible only in the 1--4 keV energy range, during an observation obtained with the EXOSAT satellite in August 1984. A search for d...
1994-07-28
2009-10-22
[ "astro-ph" ]
G.L. Israel, S. Mereghetti and L. Stella
astro-ph/9407087
Quantum Diffusion of Planck Mass and the Evolution of the Universe
A theory of evolution for the Universe requires both a mutation mechanism and a selection mechanism. We propose that both can be encountered in the stochastic approach to quantum cosmology. In Brans--Dicke chaotic inflation, the quantum fluctuations of Planck mass behave as mutations, such that new inflationary domains...
1994-07-27
2009-10-22
[ "astro-ph", "gr-qc", "hep-th" ]
Juan Garcia-Bellido
astro-ph/9407090
BATSE Observations of Gamma-Ray Burst Spectra. II. Peak Energy Evolution in Bright, Long Bursts -
We investigate spectral evolution in 37 bright, long gamma-ray bursts observed with the BATSE Spectroscopy Detectors. High resolution spectra are characterized by the energy of the peak of \nfn~and the evolution of this quantity is examined relative to the emission intensity. In most cases it is found that this peak en...
1994-07-27
2009-10-22
[ "astro-ph" ]
L.A. Ford, D.L. Band, J.L. Matteson, M.S. Briggs, G.N. Pendleton, R.D. Preece, W.S. Paciesas, B.J. Teegarden, D.M. Palmer, B.E. Schaefer, T.L. Cline, G.J. Fishman, C. Kouveliotou, C.A. Meegan, R.B. Wilson, and J.P. Lestrade
astro-ph/9407088
A Near-Infrared Variant of the Barnes-Evans Method For Finding Cepheid Distances Calibrated with High-Precision Angular Diameters
The advantages of a near-infrared variant of the Barnes-Evans method for estimating distances to Cepheid variables are described and quantified. A surface brightness-color relation for $K$ photometry and the $(V-K)_0$ color index is established using modern, high-precision angular diameters from optical interferometers...
1994-07-27
2009-10-22
[ "astro-ph" ]
D.L. Welch
astro-ph/9407089
When Can Non-Gaussian Density Fields Produce a Gaussian Sachs-Wolfe Effect?
The Sachs-Wolfe temperature fluctuations produced by primordial density perturbations are proportional to the potential field \phi, which is a weighted integral over the density field \delta. Because of the central limit theorem, \phi can be approximately Gaussian even when \delta is non-Gaussian. Using the Wold repres...
1994-07-27
2011-05-12
[ "astro-ph" ]
Robert J. Scherrer and Robert K. Schaefer
astro-ph/9407085
Do Galactic Systems Form Too Late in Cold+Hot Dark Matter Models?
The abundance of galactic systems at high redshifts can impose a strong constraint on the cold+hot dark matter (CDM+HDM) models. The hot component reduces the excessive small-scale power in the COBE-normalized CDM model but also delays the epoch of galaxy formation. We present results from the first numerical simulatio...
1994-07-26
2009-10-22
[ "astro-ph", "hep-ph" ]
Chung-Pei Ma and Edmund Bertschinger
astro-ph/9407084
The Optical Gravitational Lensing Experiment. OGLE #7: Binary Microlens or a New Unusual Variable?
We present the light curve of an unusual variable object, OGLE #7, detected during the OGLE search for microlensing events. After one season of being in a low, normal state, the star brightened by more than 2~mag with a characteristic double-maximum shape, and returned to normal brightness after 60 days. We consider po...
1994-07-26
2009-10-22
[ "astro-ph" ]
A. Udalski, M. Szymanski, S. Mao, R. Di Stefano, J. Kaluzny, M. Kubiak, M. Mateo, and W. Krzeminski
astro-ph/9407081
High Velocity Oblique Cloud Collision and Star and Star Cluster Formation through Gravitational Instability of the Shock-Compressed Slab with Rotation and Velocity Shear
We study the gravitational instability of an isothermal gaseous slab formed by cloud-cloud collision and compression at the cloud interface. The compressed gaseous slab rotates and has velocity shear except when the collision is not exactly head-on. The effects of the rotation and velocity shear on the gravitational in...
1994-07-26
2007-05-23
[ "astro-ph" ]
Masatoshi Usami, Tomoyuki Hanawa, and Mitsuaki Fujimoto
astro-ph/9407083
High-Order Correlations of Rich Galaxy Clusters
We analyse the two--dimensional all--sky distribution of rich Abell and ACO galaxy clusters by using counts in cells and measuring the high--order area--averaged angular correlation functions. Confirming previous results, we find a well defined hierarchical relation between the two and three--point correlation function...
1994-07-26
2009-10-22
[ "astro-ph" ]
A.Cappi & S.Maurogordato
astro-ph/9407080
A Possible Optical Counterpart for the Triple Pulsar System PSR B1620-26
We have searched deep optical images of the globular cluster M4 for a possible optical counterpart for the third body in the PSR B1620-26 system. We identify as a possible optical counterpart a star located within $0.3''$ of the nominal pulsar position with $V\approx 20$. This magnitude is consistent with a main sequen...
1994-07-26
2009-10-22
[ "astro-ph" ]
C. D. Bailyn, E. P. Rubenstein, T. M. Girard, D. Dinescu, F. A. Rasio, and B. Yanny
astro-ph/9407082
About the Malmquist bias in the determination of H0 and of distances of galaxies
We provide the mathematical framework which elucidates the way of using a Tully-Fisher (TF) like relation in the determination of the Hubble constant $H_0$, as well as for distances of galaxies. The methods related to the so-called Direct and Inverse TF Relations (herein DTF and ITF) are interpreted as maximum likeliho...
1994-07-26
2019-08-17
[ "astro-ph" ]
R.Triay, M.Lachieze-Rey, S.Rauzy
astro-ph/9407086
Low Mass X-Ray Binaries in Globular Clusters: A New Metallicity Effect
Galactic Globular Clusters (GCs) containing bright X sources (L_x > 10^{36} erg/s), commonly associated with Low Mass X-Ray Binaries (LMXBs), are found to be significantly denser and more metal-rich than normal non-X-ray clusters both in the Galaxy and in M31. Within a framework where LMXBs in GCs are generated via tid...
1994-07-26
2009-10-22
[ "astro-ph" ]
M. Bellazzini, A. Pasquali, L. Federici, F.R. Ferraro, F. Fusi Pecci
astro-ph/9407074
Dark Filaments in the Galaxy NGC 253 - a Boiling Galactic Disk -
We study the morphology of dark lanes and filaments in the dust-rich galaxy NGC 253 using an unsharp-masked $B$-band optical photograph. Dust features are classified as `arcs', which have heights and scale radius of about 100 to 300 pc, connecting two or more dark clouds, and `loops' and `bubbles', which are developed ...
1994-07-25
2009-10-22
[ "astro-ph" ]
Yoshiaki Sofue, Ken-ichi Wakamatsu, and David F. Malin
astro-ph/9407077
Ubv CCD Standards Near 5C1 Radio Sources at Intermediate Galactic Latitude-I
We have been doing a photometric and astrometric sample survey programme on Schmidt plates in a few selected directions in the Galaxy with an aim to study galactic stellar populations. In order to calibrate Schmidt plates photometrically, it is necessary to have a number of photometric standards which cover the entire ...
1994-07-25
2007-05-23
[ "astro-ph" ]
V.Mohan, D.K.Ojha, O.Bienayme, D.C.Paliwal, A.K.Pandey, A.C.Robin, M.Chareton, B.C.Bhatt, B.B.Sanwal, E.Oblak, M. Haywood and M.Creze
astro-ph/9407079
Bias and high-order galaxy correlation functions in the APM Galaxy Survey
On large scales, the higher order moments of the mass distribution, $S_J=\xibar_J/\xibar_2^{J-1}$, e.g., the skewness $S_3$ and kurtosis $S_4$, can be predicted using non-linear perturbation theory. Comparison of these predictions with moments of the observed galaxy distribution probes the bias between galaxies and mas...
1994-07-25
2009-10-22
[ "astro-ph" ]
E. Gaztanaga and J. Frieman
astro-ph/9407076
The Two-Point Correlation Function of Rich Clusters of Galaxies: Results from an Extended APM Cluster Redshift Survey
We present new estimates of the spatial two-point correlation function of rich clusters of galaxies selected from the APM Galaxy Survey. We have measured redshifts for a sample of $364$ clusters out to a depth of $\sim 450\hmpc$. The clusters have a mean space density of $\bar{n} = 3.4\times 10^{-5}\hmpccc$. The two-po...
1994-07-25
2016-06-08
[ "astro-ph" ]
G.B. Dalton, R.A.C. Croft, G. Efstathiou, W.J. Sutherland, S.J. Maddox, & M. Davis
astro-ph/9407075
A Multicolor Survey of Absolute Proper Motions : Galactic Structure and Kinematics in the Direction of Galactic Center at Intermediate Latitude
We have derived a new photographic photometry and proper motions for 20000 stars with completeness to V = 18 in the direction of galactic center at the intermediate latitude (l = 3 deg,b = 47 deg; alpha(1950)=15h 18m, delta(1950) = +02deg 16') for a 15.5 sq deg field. The combination of four glass copies of the Palomar...
1994-07-25
2007-05-23
[ "astro-ph" ]
D.K.Ojha, O.Bienayme, A.C.Robin and V.Mohan
astro-ph/9407078
A Giant Arc in a ROSAT Detected Cluster of Galaxies
We report the serendipitous discovery of a giant grvitational arc in the Abell Supplementary cluster S295 during optical follow-up observations of clusters detected in the ROSAT All-Sky Survey. The cluster has a redshift z=0.3007 and a velocity dispersion of about 900 km/sec. This is the first giant arc newly found in ...
1994-07-25
2007-05-23
[ "astro-ph" ]
A.C.Edge, H.Boehringer, L.Guzzo, et al
astro-ph/9407071
Exact Solutions and Approximations of Mond Fields of Disk Galaxies
We Consider models of thin disks (with and without bulges) in the Bekenstein-Milgrom formulation of MOND as a modification of Newtonian gravity. Analytic solutions are found for the full gravitational fields of Kuzmin disks, and of disk-plus-bulge generalizations of them. For all these models a simple algebraic relat...
1994-07-24
2007-05-23
[ "astro-ph" ]
R.Brada and M.Milgrom (Weizmann Institute of Science)
astro-ph/9407073
The Existence of Baryons at z=1000
Fluctuations in the CMB have now been detected over a wide range of angular scales, and a consistent picture seems to be emerging. The data cannot currently constrain a large number of cosmological parameters, but it is clear that there is more information than just the normalization of the models. Here we use the data...
1994-07-24
2009-09-25
[ "astro-ph" ]
Douglas Scott and Martin White
astro-ph/9407072
Tests of General Relativity at Large Distances and Dark Matter -
The most simple observed cases of gravitational lensing of distant quasars and galaxies by galaxies and clusters of galaxies are used to test Einstein's theory of General Relativity and Newtonian Gravity over galactic and intergalactic distances. They extend the distance range over which Newton-Einstein Gravity has bee...
1994-07-24
2009-09-25
[ "astro-ph" ]
Arnon Dar
astro-ph/9407066
The Formation of Disk Galaxies in a Cosmological Context: Structure and Kinematics
We present results concerning the internal structure and kinematics of disk galaxies formed in cosmologically motivated simulations. The calculations include dark matter, gas dynamics, radiative cooling, star formation, supernova feedback and metal enrichment. The initial model is a rigidly rotating overdense sphere wi...
1994-07-22
2015-06-24
[ "astro-ph" ]
Matthias Steinmetz & Ewald Mueller
astro-ph/9407068
A Faint Luminous Halo that May Trace the Dark Matter around Spiral Galaxy NGC~5907
The presence of unseen halos of ``dark matter'' has long been inferred from the high rotation speeds of gas and stars in the outer parts of spiral galaxies$^{1}$. The volume density of this dark matter decreases less quickly from the galactic center than does that of the luminous mass (such as that in stars), meaning t...
1994-07-22
2009-10-22
[ "astro-ph" ]
Penny D. Sackett, Heather L. Morrison, Paul Harding, and Todd A. Boroson
astro-ph/9407070
First Observations of Individual Molecular Clouds in the Irregular Galaxy NGC 6822
Three molecular clouds have been mapped in the nearby metal-poor dwarf irregular galaxy NGC 6822 using the Owens Valley Millimeter-Wave Interferometer. Based on upper limits to the virial masses of the clouds, the CO-to-H2 conversion factor in NGC 6822 is <2.2+/-1.3 times larger than the Galactic value. Conversion fact...
1994-07-22
2009-10-22
[ "astro-ph" ]
C. D. Wilson
astro-ph/9407069
Cosmological-Constant Cold Dark Matter Models and the COBE Two-Year Sky maps
We compare the two-year COBE DMR sky maps with the predictions of cosmological-constant cold dark matter models. Using a Bayesian analysis, we find that the most likely value of the cosmological constant in such a model is Lambda = 0. The data set an upper limit on Lambda of 0.78 (0.85) at 90% confidence, and 0.86 (0.9...
1994-07-22
2009-10-22
[ "astro-ph" ]
Emory F. Bunn and Naoshi Sugiyama
astro-ph/9407067
X--Ray Spectra from Neutron Stars Accreting at Low Rates
The spectral properties of X--ray radiation produced in a static atmosphere around a neutron star accreting at very low rates are investigated. Previous results by Alme \& Wilson (1973) are extended to the range $10^{-7}\leq L/L_{Edd}\leq 10^{-3}$ to include the typical luminosities, $L\sim 10^{31}-10^{32} \ {\rm ergs\...
1994-07-22
2009-10-22
[ "astro-ph" ]
Luca Zampieri, Roberto Turolla, Silvia Zane and Aldo Treves
astro-ph/9407065
Stars within the Large Magellanic Cloud as Potential Lenses for Observed Microlensing Events
Massive Compact objects in the halo, known as MACHOs, have been postulated as the origin of a substantial fraction of `dark matter' known to exist in the haloes of galaxies$^{1,2}$. Paczy\'nski$^3$ has suggested that it might possible to detect these low-luminosity objects by their potential to act as gravitational len...
1994-07-21
2015-06-24
[ "astro-ph" ]
Kailash C. Sahu
astro-ph/9407064
The Effects of Electro-weak Phase Transition Dynamics on Baryogenesis and Primordial Nucleosynthesis
The evolution of the electro-weak phase transition, including reheating due to the release of latent heat in shock waves, is calculated for various values of as yet unknown parameters of electro-weak theory such as latent heat and bubble wall surface tension. We show that baryon production, which occurs in the vicinity...
1994-07-21
2010-11-01
[ "astro-ph" ]
Andrew F. Heckler
astro-ph/9407063
The Dynamics of Flux Tubes in a High Beta Plasma
We suggest a new model for the structure of a magnetic field embedded high $\beta$ turbulent plasma, based on the popular notion that the magnetic field will tend to separate into individual flux tubes. We point out that interactions between the flux tubes will be dominated by coherent effects stemming from the turbule...
1994-07-21
2007-05-23
[ "astro-ph" ]
E.T. Vishniac
astro-ph/9407060
First Order Inflation in General Relativity
I give a general formulation of the constraints on models of inflation ended by a first order phase transition arising from the requirement that they do not produce too many large (observable) true vacuum voids -- the `big bubble problem'. It is shown that this constraint can be satisfied by a simple model in Einstein ...
1994-07-20
2009-10-22
[ "astro-ph" ]
David Wands
astro-ph/9407055
Studying Starlight from Distant Galaxies with SIRTF
Starlight from distant galaxies ($z > 3$) is redshifted into the near infrared band with observed wavelengths from 2-8 $\mu$m. Most of the light is emitted by stars that have a peak emission at the 1.6 $\mu$m wavelength of the minimum of the H$^-$ opacity. We present simulated images of galaxy and star fields at 3, 4.7...
1994-07-20
2008-02-03
[ "astro-ph" ]
E. L. Wright, P. E. Eisenhardt and G. G. Fazio
astro-ph/9407057
The Hot End of Evolutionary Horizontal Branches
In this paper we investigate the hot end of the HB, presenting evolutionary constraints concerning the CM diagram location and the gravity of hot HB stars. According to the adopted evolutionary scenario, we predict an upper limit for HB temperatures of about logTe = 4.45, remarkably cooler than previous estimates. We f...
1994-07-20
2009-10-22
[ "astro-ph" ]
V.Castellani, S. Degl'Innocenti and L. Pulone
astro-ph/9407058
HB Morphology and Age Indicators for Metal-Poor Stellar Systems with Age in the Range of 1 to 20 Gyr
Isochrone computations and horizontal branch (HB) models for Y(MS)=0.23 and two values of Z (0.0001, 0.0004)are used to derive constraints on the age indicators and HB morphology of metal-poor clusters with age t (in Gyrs) in the range of 1< t < 20.It is found that for fixed metallicity the luminosity L(3.83) of the ze...
1994-07-20
2007-05-23
[ "astro-ph" ]
F. Caputo, S. Degl'Innocent
astro-ph/9407062
Cosmic Microwave Background Anisotropies and the Geometry of the Universe
In this talk, I review some recent work on cosmic microwave background (CMB) anisotropies in an open universe. I emphasize that the observed CMB anisotropies are still consistent with a low value of $\Omega$, and I address the question of whether future CMB measurements will be able to provide information on the geomet...
1994-07-20
2007-05-23
[ "astro-ph", "hep-ph" ]
Marc Kamionkowski
astro-ph/9407061
The Case for a Hubble Constant of 30 km/s/Mpc
Although cosmologists have been trying to determine the value of the Hubble constant for nearly 65 years, they have only succeeded in limiting the range of possibilities: most of the current observational determinations place the Hubble constant between 50 km/s/Mpc and 90 km/s/Mpc. The uncertainty is unfortunate becaus...
1994-07-20
2009-10-22
[ "astro-ph" ]
J.G. Bartlett, A. Blanchard, J. Silk and M.S. Turner
astro-ph/9407059
Physically Detached "Compact Groups"
A small fraction of galaxies appear to reside in dense compact groups, whose inferred crossing times are much shorter than a Hubble time. These short crossing times have led to considerable disagreement about the dynamical state of these systems. We suggest that many of the observed groups are not physically bound but ...
1994-07-20
2009-10-22
[ "astro-ph" ]
Lars Hernquist, Neal Katz, and David Weinberg
astro-ph/9407056
COBE Tutorial and Recent Results
Some of the technical details involved in taking and analyzing data from COBE are discussed, and recent results from the FIRAS and DMR experiments are summarized. Some of the cosmological implications of these recent data are presented.
1994-07-20
2007-05-23
[ "astro-ph" ]
Edward L. Wright
astro-ph/9407054
A Local View of the Observable Universe
We present results on the non-linear dynamics of inhomogeneous cosmological models with irrotational dust and a positive cosmological constant, considering, in particular, a wide class with vanishing magnetic Weyl tensor. For those patches of the universe that do not recollapse to a singularity we find a unique attract...
1994-07-18
2009-10-22
[ "astro-ph" ]
M.Bruni, S. Matarrese and O. Pantano
astro-ph/9407052
A Mapping for the Gravitational Few-Body Problem with Dissipation
Recently a new class of numerical integration methods -- ``mixed variable symplectic integrators'' -- has been introduced for studying long-term evolution in the conservative gravitational few-body problem. These integrators are an order of magnitude faster than conventional ODE integration methods. Here I present a si...
1994-07-16
2009-10-22
[ "astro-ph", "chao-dyn", "nlin.CD" ]
Renu Malhotra (Lunar & Planetary Institute)
astro-ph/9407047
M_1 - M* Correlation in Galaxy Clusters
Photographic F band photometry of a sample of 36 Abell clusters has been used to study the relation between the magnitude $M_1$ of the brightest cluster member and the Schechter function parameter $M^*$. Clusters appear segregated in the $M_1$-$M^*$ plane according to their Rood \& Sastry class. We prove on a statistic...
1994-07-15
2007-05-23
[ "astro-ph" ]
D. Trevese, G. Cirimele and B. Appodia
astro-ph/9407051
Temperature Anisotropies in a Universe with Global Defects
We present a technique of calculating microwave anisotropies from global defects in a reionised universe. We concentrate on angular scales down to one degree where we expect the nongaussianity of the temperature anisotropy in these models to become apparent.
1994-07-15
2007-05-23
[ "astro-ph" ]
David Coulson
astro-ph/9407046
Skewness of CMB Anisotropies in an Inflationary Isocurvature Baryon Model
We investigate the cosmic variance of the skewness of the cosmic microwave background (CMB) anisotropies in an inflationary model which leads to the baryon isocurvature scenario for the cosmic structure formation. In this model, the baryon number fluctuations are given by a sinusoidal function of a random Gaussian fiel...
1994-07-15
2016-08-30
[ "astro-ph" ]
Kazuhiro Yamamoto and Misao Sasaki
astro-ph/9407048
How Many Solar Neutrino Experiments Are Wrong?
Ten recently-published solar models give $\7be$ neutrino fluxes that lie within a range of $\pm 10$\% of the average value, a convergence that is independent of uncertainties in the measured laboratory rate of the $\7be(p,\gamma)\8b$ reaction. If nothing happens to solar neutrinos after they are created ({\it a la} sta...
1994-07-15
2008-11-26
[ "astro-ph" ]
John N. Bahcall
astro-ph/9407053
A Gauss-Hermite Expansion of the Galactic Globular Cluster Luminosity Function
We decompose the luminosity function of Galactic globular clusters into a sum of the orthogonal Gauss-Hermite functions. This method quantifies the asymmetric third-order ($h_3$) and symmetric fourth-order ($h_4$) terms of the distribution while minimizing the effect of outliers in the data. For 138 Galactic globulars ...
1994-07-15
2009-10-22
[ "astro-ph" ]
Roberto G. Abraham and Sidney Van Den Bergh (Dominion Astrophysical Observatory Herzberg Institute of Astrophysics National Research Council Canada Victoria, BC, V8X 4M6, Canada)
astro-ph/9407049
Redshift Distortions of Clustering: A Lagrangian Approach
We study the effects of peculiar velocities on statistical measures of galaxy clustering. These effects occur when distances to the galaxies are estimated from their redshifts. It is assumed that the clustering pattern results from the gravitational instability of initially Gaussian, small-amplitude perturbations of a ...
1994-07-15
2011-05-23
[ "astro-ph" ]
E. Hivon, F.R. Bouchet, S. Colombi, R. Juszkiewicz
astro-ph/9407050
On the Shape of the First Collapsed Objects
Since the early seventies, there was a conjecture that the first collapse of a selfgravitating dust--like medium (appropriate approximation for nonbaryonic dark matter) results in the formation of a ``pancake" object, that is a thin surface. The conjecture has been based on the Zel'dovich approximate solution of the no...
1994-07-15
2009-10-22
[ "astro-ph", "gr-qc" ]
S.F. Shandarin, A.L. Melott, K. McDavitt, J.L. Pauls, J. Tinker
astro-ph/9407043
The Supernova Ring Revisited II: Distance to the LMC
I derive an upper limit to the distance to SN 1987A of $\dsn<46.77\pm 0.76\,\kpc$, or a distance modulus $\mu_\sn<18.350\pm 0.035$. If SN 1987A lies in the plane of the Large Magellanic Cloud (LMC) and hence 500 pc in front of the LMC center, this implies $\mu_\lmc<18.37\pm 0.04$. The determination rests on a new measu...
1994-07-14
2009-10-22
[ "astro-ph" ]
Andrew Gould
astro-ph/9407041
Scaling Analysis of the Galaxy Distribution in the SSRS Catalog
A detailed analysis of the galaxy distribution in the Southern Sky Redshift Survey (SSRS) by means of the multifractal or scaling formalism is presented. It is shown that galaxies cluster in different ways according to their morphological type as well as their size. Ellipticals are more clustered than spirals, even at ...
1994-07-14
2009-10-22
[ "astro-ph" ]
A. Campos, R. Dominguez-Tenreiro and G. Yepes
astro-ph/9407039
Gamma Ray Bursts from Minijets
Striking similarities exist between high energy gamma ray emission from active galactic nuclei (AGN) and gamma ray bursts (GRBs). They suggest that GRBs are generated by inverse Compton scattering from highly relativistic electrons in transient jets. Such jets may be produced along the axis of an accretion disk formed ...
1994-07-14
2009-10-22
[ "astro-ph" ]
Nir J. Shaviv and Arnon Dar
astro-ph/9407044
Signal-to-Noise Eigenmode Analysis of the Two-Year COBE Maps
To test a theory of cosmic microwave background fluctuations, it is natural to expand an anisotropy map in an uncorrelated basis of linear combinations of pixel amplitudes --- statistically-independent for both the noise and the signal. These $S/N$-eigenmodes are indispensible for rapid Bayesian analyses of anisotropy ...
1994-07-14
2009-01-23
[ "astro-ph", "gr-qc", "hep-ph" ]
J. Richard Bond
astro-ph/9407040
Mutated Hybrid Inflation
A new model of inflation is described. An unusual form for the inflationary potential is obtained because the inflaton corresponds to a non-trivial path in the configuration space of the two real scalar fields of the model. The model predicts a spectral index $n = 1 - 3/2N \simeq 0.97$ for the density perturbations and...
1994-07-14
2009-10-22
[ "astro-ph", "hep-ph" ]
Ewan D. Stewart
astro-ph/9407042
Cosmic Microwave Background Radiation Anisotropy Induced by Cosmic Strings
We report on a current investigation of the anisotropy pattern induced by cosmic strings on the cosmic microwave background radiation (MBR). We have numerically evolved a network of cosmic strings from a redshift of $Z = 100$ to the present and calculated the anisotropies which they induce. Based on a limited number of...
1994-07-14
2007-05-23
[ "astro-ph" ]
B. Allen, R. R. Caldwell, E. P. S. Shellard, A. Stebbins, and S. Veeraraghavan
astro-ph/9407038
Giant Branch Mixing and the Ultimate Fate of Primordial Deuterium in the Galaxy
The observed cosmic abundances of light elements are most consistent with each other, and with the predictions of big bang nucleosynthesis,if, contrary to the usual assumption, galactic chemical evolution reduces $(D+\ ^3He)/H$ with time. Chemical evolution models which do this require that low mass stars destroy $^3He...
1994-07-13
2009-10-22
[ "astro-ph" ]
Craig J. Hogan
astro-ph/9407037
Detectability of Tensor Perturbations Through CBR Anisotropy (final published version)
Detection of the tensor perturbations predicted in inflationary models is important for testing inflation as well as for reconstructing the inflationary potential. We show that because of cosmic variance the tensor contribution to the square of the CBR quadrupole anisotropy must be greater than about 20\% of the scalar...
1994-07-13
2009-09-25
[ "astro-ph" ]
Lloyd Knox and Michael S. Turner
astro-ph/9407036
Cosmological Observations in a Local Void
A local void in the globally Friedmann-Robertson-Walker (FRW) cosmological model is studied. The inhomogeneity is described using the Lema\^{\i}tre-Tolman-Bondi (LTB) solution with the spherically symmetric matter distribution based on the faint galaxies number counts. We investigate the effects this has on the measure...
1994-07-13
2009-10-22
[ "astro-ph" ]
J.W.Moffat and D.C.Tatarski
astro-ph/9407034
On Constraining Electroweak-Baryogenesis with Inhomogeneous Primordial Nucleosynthesis
Primordial nucleosynthesis calculations are shown to be able to provide constraints on electroweak baryogenesis which produce a highly inhomogeneous distribution of the baryon-to-photon ratio. Such baryogenesis scenarios overproduce 4He and/or 7Li and can be ruled out whenever a fraction f<3*10e-6(100 GeV/T)^3 of nucle...
1994-07-12
2009-10-22
[ "astro-ph", "hep-ph" ]
G.M. Fuller, K. Jedamzik, G.J. Mathews, and A. Olinto
astro-ph/9407033
The Angular Correlation Function of Galaxies in CDM and CHDM Models
We estimate the angular correlation function for the standard CDM, tilted $n=0.7$ CDM and hybrid (CHDM) models, and compare with observations. When compared with the APM observational results scaled to the Lick depth, there appears to be fair agreement with the estimate from the CHDM model. But a more detailed comparis...
1994-07-12
2007-05-23
[ "astro-ph" ]
G. Yepes, A. Klypin, A. Campos and R. Fong
astro-ph/9407032
Steps towards Nonlinear Cluster Inversion Through Gravitational Distortions. I. Basic Considerations and Circular Clusters
The distortion of images of faint, high-redshift galaxies by light deflection at foreground clusters of galaxies can be used to determine the (projected) mass distribution of the clusters. In the case of strong distortions, which lead to arcs in clusters, the position of the arc and/or its radius of curvature yields an...
1994-07-12
2007-05-23
[ "astro-ph" ]
Peter Schneider and Carolin Seitz
astro-ph/9407035
Absence of a Lower Limit on Omega_b in Inhomogeneous Primordial Nucleosynthesis
We show that a class of inhomogeneous big bang nucleosynthesis models exist which yield light-element abundances in agreement with observational constraints for baryon-to-photon ratios significantly smaller than those inferred from standard homogeneous big bang nucleosynthesis (HBBN). These inhomogeneous nucleosynthesi...
1994-07-12
2009-10-22
[ "astro-ph" ]
K. Jedamzik, G.J. Mathews, and G.M. Fuller
astro-ph/9407028
The Quasar Distribution in a Static Universe
A crucial test of any cosmological model is the distribution of distant objects such as quasars. Because of well defined selection criteria quasars found by a ultraviolet excess (UVX) survey are ideal candidates for testing the model out to a redshift of z = 2.2. The static cosmology proposed by Crawford (1993) is used...
1994-07-11
2009-10-22
[ "astro-ph" ]
David F. Crawford
astro-ph/9407031
The Radio Lifetime of Supernova Remnants and the Distribution of Pulsar Velocities at Birth
We have made VLA images of the fields around three young pulsars which have resulted in the discovery of two new supernova remnants and confirmation of a third. We argue that, in at least two cases and perhaps the third, the pulsars are physically associated with these supernova remnants. A review of all known young pu...
1994-07-11
2009-10-22
[ "astro-ph" ]
D. A. Frail, W. M. Goss, and J. B. Z. Whiteoak
astro-ph/9407029
Angular Size in a Static Universe
In principle the geometry of the universe can be investigated by measuring the angular size of known objects as a function of distance. Thus the distribution of angular sizes provides a critical test of the stable and static model of the universe described by Crawford (1991,1993) that has a simple and explicit relation...
1994-07-11
2009-10-22
[ "astro-ph" ]
David F. Crawford