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astro-ph/9409024
Signatures of Bulge Triaxiality from Kinematics in Baade's Window/
We study a sample of 62 Baade's Window (1,-4) K giants that have published proper motions, radial velocity and metallicity. We construct the velocity ellipsoids for the metal rich stars and metal poor stars. We find a vertex deviation characteristic of a non-axisymmetric system. The long axes of the velocity ellipsoids...
1994-09-12
2019-08-17
[ "astro-ph" ]
HongSheng Zhao, D.N.Spergel, R.M.Rich
astro-ph/9409025
A Search for the Radio Counterpart to the March 1, 1994 Gamma Ray Burst
We report on the results of a search for the radio counterpart to the bright gamma-ray burst of March 1, 1994. Using the Dominion Radio Astrophysical Observatory Synthesis Telescope sensitive, wide-field radio images at 1.4 GHz and 0.4 GHz were made of a region around GRB940301. A total of 15 separate radio images were...
1994-09-12
2009-10-22
[ "astro-ph" ]
Frail, Kulkarni, Hurley, Fishman, Kouveliotou, Meegan, Sommer, Boer, Niel, and Cline
astro-ph/9409023
New observational limits on dynamo saturation in young solar-type stars
We present statistically robust observational evidence which imposes new limits on dynamo saturation in young solar-type stars. These are inferred from the increasing amplitude of the V-band optical flux with rotation, caused by the filling of the disc with surface spots in a non-axisymmetric pattern. Assuming spot cov...
1994-09-12
2007-05-23
[ "astro-ph" ]
Mark A. O'Dell, Peter M. Panagi, Martin A. Hendry and Andrew Collier-Cameron(University of Sussex, Brighton BN1 9QH)
astro-ph/9409022
Microlensing by the Galactic Bar
We compute the predicted optical depth and duration distribution of microlensing events towards Baade's window in a model composed of a Galactic disk and a bar. The bar model is a self-consistent dynamical model built out of individual orbits that has been populated to be consistent with the COBE maps of the Galaxy and...
1994-09-11
2009-10-22
[ "astro-ph" ]
HongSheng Zhao (1), David N. Spergel (2), R. Michael Rich (1) ((1) Columbia U., (2) Princeton U.)
astro-ph/9409019
Variability of Accretion Disks Surrounding Black Holes ----- the Role of Inertial-Acoustic Mode Instabilities
The global nonlinear time-dependent evolution of the inertial-acoustic mode instability in accretion disks surrounding black holes has been investigated. The viscous stress is assumed to be proportional to the gas pressure only, i.e.\,, $\tau = - \alpha p_g$. It is found that an oscillatory instability exists in the in...
1994-09-09
2009-10-22
[ "astro-ph" ]
Xingming Chen and Ronald E. Taam (Northwestern University)
astro-ph/9409020
An Arcminute Resolution Search at 4.7CM^-1 for Point Sources in Msam and Max Fields
We have searched for mm-wave emission from compact objects in two fields, each approximately 1 square degree in size, taken from regions of the sky in which degree-scale structure in the Cosmic Background Radiation (CBR) has recently been reported. The observations were made at frequency of 4.7~cm^-1 and with an angula...
1994-09-09
2007-05-23
[ "astro-ph" ]
S.E. Church, P.D. Mauskopf, P.A.R. Ade, M.J. Devlin, W.L. Holzapfel, T.M. Wilbanks, A.E. Lange
astro-ph/9409018
Thermal Equilibria of Accretion Disks
We show that most of hot, optically thin accretion disk models which ignore advective cooling are not self-consistent. We have found new types of optically thin disk solutions where cooling is dominated by radial advection of heat. These new solutions are thermally and viscously stable.
1994-09-09
2009-10-22
[ "astro-ph" ]
Marek A. Abramowicz, Xingming Chen, Shoji Kato, Jean-Pierre Lasota, and Oded Regev
astro-ph/9409021
A New Parallel N-body Gravity Solver: TPM
We have developed a gravity solver based on combining the well developed Particle-Mesh (PM) method and TREE methods. It is designed for and has been implemented on parallel computer architectures. The new code can deal with tens of millions of particles on current computers, with the calculation done on a parallel supe...
1994-09-09
2009-10-22
[ "astro-ph" ]
Guohong Xu
astro-ph/9409017
Gravitational Collapse of Small-Scale Structure as the Origin of the Lyman Alpha Forest
If gravitational clustering is a hierarchical process, the present large-scale structure of the galaxy distribution implies that structures on smaller scales must have formed at high redshift. We simulate the formation of small-scale structure (average cell mass: $\Delta \bar m_b=10^{4.2}$M$_\odot$) and the evolution o...
1994-09-08
2009-10-22
[ "astro-ph" ]
Renyue Cen, Jordi Miralda-Escude, Jeremiah P. Ostriker and Michael Rauch (Princeton University Observatory, Princeton, NJ USA)
astro-ph/9409014
Models of Galaxies with Central Black Holes: Simulation Methods
We present a method for simulating numerically the effect of the adiabatic growth of black holes on the structure of elliptical galaxies. Using a parallel self--consistent field code, we add black holes to N--body realizations of model distribution functions for spherical galaxies, using a continuous mass--spectrum. Th...
1994-09-07
2009-10-22
[ "astro-ph" ]
Steinn Sigurdsson, Lars Hernquist and Gerald D. Quinlan
astro-ph/9409016
Assessing the Accuracy of Masses and Spatial Correlations of Galaxy Groups
Two algorithms for the identification of galaxy groups from redshift surveys are tested by application to simulated data derived from N-body simulation. The accuracy of the membership assignments by these algorithms is studied in a companion to this paper (Frederic 1994). Here we evaluate the accuracy of group mass est...
1994-09-07
2009-10-22
[ "astro-ph" ]
James J. Frederic
astro-ph/9409015
Testing the Accuracy of Redshift Space Group Finding Algorithms
Using simulated redshift surveys generated from a high resolution N-body cosmological structure simulation, we study algorithms used to identify groups of galaxies in redshift space. Two algorithms are investigated; both are friends-of-friends schemes with variable linking lengths in the radial and transverse dimension...
1994-09-07
2009-10-22
[ "astro-ph" ]
James J. Frederic
astro-ph/9409013
Star Formation in Dwarf Irregular Galaxies: NGC 6822
Our proposed method to study the star formation histories in nearby irregulars is here applied to NGC 6822. To this purpose we have obtained accurate CCD photometry of three regions in the galaxy, reaching V$\simeq$23.5 with an accuracy of $\sigma_{BVR}\leq$0.1 mag. The comparison of the observational color-magnitude d...
1994-09-06
2009-10-22
[ "astro-ph" ]
G. Marconi, M. Tosi, L. Greggio and P. Focardi
astro-ph/9409011
The Shapes of Galaxy Clusters
We have reanalyzed a data set of 99 low redshift ($ z < 0.1 $) Abell clusters and determined their shapes. For this, three different measures are used. We use Monte-Carlo simulations to investigate the errors in the methods. The corrected distribution of cluster ellipticities shows a peak at $ \epsilon \sim 0.4 $ and e...
1994-09-06
2015-06-24
[ "astro-ph" ]
P.A.M. de Theije, P. Katgert, E. van Kampen
astro-ph/9409012
Rapid Stochastic Acceleration of Protons to Energies Above 100~TeV in the Accretion Column Of Hercules X-1
An investigation into the acceleration of protons by scattering off relativistic Alfv\'{e}n waves in the accretion column of Hercules X-1 is presented. The mechanism is shown to achieve mean particle energies of 30~TeV under very reasonable assumptions about the environment, and 250~TeV is available under some circumst...
1994-09-06
2009-10-22
[ "astro-ph" ]
P. A. Johnson
astro-ph/9409010
Limits on possible magnetic fields at nucleosynthesis time
In this paper we discuss limits on magnetic fields that could have been present at nucleosynthesis time. We considered several effects that could be relevant modifing light elements relic abundances. They include: changes in reaction rates, mass shifts due to strong and electromagnetic interactions, variation of the ex...
1994-09-05
2011-05-23
[ "astro-ph" ]
D. Grasso and H.R. Rubistein
astro-ph/9409009
Generalized Van Cittert Zernike Theorem in Curved Spacetime - Some Astrophysical Applications
The {\em Van Cittert Zernike} theorem consists of a simple relation between the measured coherence of the radiation and the characteristics of the emitting stochastic source. In the present work, an extension of the theorem to partially correlated sources in curved spacetime is derived. The generalized theorem is used ...
1994-09-03
2007-05-23
[ "astro-ph" ]
G. Hazak and R. Zamir
astro-ph/9409006
The Spatial Distribution, Kinematics, and Dynamics of the Galaxies in the Region of Abell 2634 and 2666
A total of 663 galaxies with known redshifts in a $6\deg\!\times 6\deg$ field centered on A2634, including 211 new measurements, are used to study the structure of this cluster and its surroundings. Two samples, ---one containing 200 galaxies within two degrees from the cluster center and a second, magnitude-limited, o...
1994-09-02
2009-10-22
[ "astro-ph" ]
Marco Scodeggio, Jos\'e M. Solanes, Riccardo Giovanelli, and Martha P. Haynes
astro-ph/9409007
Spectroscopy of the Double Quasars Q1343+266AB: I. a New Determination of the Size of Lyman-Alpha Forest Absorbers
We have obtained spectroscopy of Q 1343+266 AB, a pair of quasars at redshift z = 2.03 with a projected separation of 9.5 arcseconds. This system is well-suited for probing the Ly-alpha forest, since the two component spectra show several Ly-alpha lines in common and several others not. Using Bayesian statistics, under...
1994-09-02
2009-10-22
[ "astro-ph" ]
Jill Bechtold, Arlin P.S. Crotts, Robert C. Duncan & Yihu Fang
astro-ph/9409004
Electromagnetic Cascades and Cascade Nucleosynthesis in the Early Universe
We describe a calculation of electromagnetic cascading in radiation and matter in the early universe initiated by the decay of massive particles or by some other process. We have used a combination of Monte Carlo and numerical techniques which enables us to use exact cross sections, where known, for all the relevant pr...
1994-09-02
2011-05-12
[ "astro-ph" ]
R.J. Protheroe, T. Stanev and V.S. Berezinsky
astro-ph/9409008
Spectroscopy of the Double Quasars Q1343+264 Ab: II. the Relationship between Galaxies Ans QSO C~IV Absorption Lines -
We present spectra of QSOs 1343+266 A B, covering Ly-beta to C~IV emission at 2\AA~resolution, and find further evidence that this system is not gravitationally lensed. We see, however, a large number of Ly-alpha and some C~IV absorption features common to both spectra. The frequency of C~IV lines in common indicates t...
1994-09-02
2009-10-22
[ "astro-ph" ]
Arlin P.S. Crotts, Jill Bechtold, Yihu Fang & Robert C. Duncan
astro-ph/9409005
The 1-Point Cluster Distribution Function and its Moments
We derive the 1-point probability density function of the smoothed 3-D Abell-ACO cluster density field and we compare it with that of artificial cluster samples, generated as high peaks of a Gaussian field in such a way that they reproduce the low-order (2- and 3-point) correlation functions and the observed cluster se...
1994-09-02
2015-06-24
[ "astro-ph" ]
M.Plionis and R.Valdarnini
astro-ph/9409002
Microlensing Maps for the Galactic Bulge
Microlensing maps -- that is, contours of equal numbers of events per $10^6$ source stars -- are provided for the inner Galaxy under two alternative hypotheses : (1) the bulge is an oblate axisymmetric spheroid or (2) the bulge is a prolate bar. Oblate spheroids yield a total of $\sim 12$ events per year per $10^6$ sta...
1994-09-01
2009-10-22
[ "astro-ph" ]
N.W. Evans
astro-ph/9409003
The COBE Normalization for Standard CDM
The COBE detection of CMB anisotropies provides the best way of fixing the amplitude of fluctuations on the largest scales. This normalization is usually given for an n=1 spectrum, including only the anisotropy caused by the Sachs- Wolfe effect. This is certainly not a good approximation for a model containing any reas...
1994-09-01
2009-10-22
[ "astro-ph" ]
E.F.Bunn, D.Scott & M.White
astro-ph/9409001
Transverse Velocities of Galaxies From Microlens Parallaxes
The transverse velocity of a spiral galaxy can be measured to an accuracy $\sim 60\,\kms$ by making parallax observations of quasars being microlensed by stars in the disk of the galaxy. To make the measurement, a quasar must be located behind the disk of the galaxy between about 1 and 2 scale lengths from the center. ...
1994-09-01
2007-05-23
[ "astro-ph" ]
Andrew Gould
astro-ph/9408102
Big Bang Nucleosynthesis and Dark Matter: Baryons and Neutrinos
I present a review of Big Bang Nucleosynthesis, concentrating on the statistical analysis of theoretical uncertainties, and on systematic errors in observed abundances. Both have important implications for constraints on the amount of baryonic dark matter and the number of light neutrino species in nature. Without allo...
1994-08-31
2008-02-03
[ "astro-ph", "hep-ph" ]
Lawrence M. Krauss
astro-ph/9408103
Cosmic Microwave Anisotropies from Topological Defects in an Open Universe
We present a general formalism for computing Cosmic Background Radiation (CBR) and density fluctuations in open models with stiff sources. We find analytic Green's functions for the linearized Einstein equations in the presence of stiff sources and use this formalism to estimate the amplitude and harmonic spectrum of m...
1994-08-31
2010-11-01
[ "astro-ph", "gr-qc" ]
Ue-Li Pen and David N. Spergel
astro-ph/9408104
Matter Distribution for Power Spectra with Broken Scale Invariance
To test the primordial power spectra predicted by a double inflationary model with a break of amplitude $\Delta=3$ at a scale of $2\pi/k\approx 10 \hm$ and CDM as dominant matter content, we perform PM simulations with 128$^3$ particles on a 256$^3$ grid. The broken scale invariance of the power spectra explains the ex...
1994-08-31
2010-11-30
[ "astro-ph" ]
L. Amendola, S. Gottloeber, J. P. Muecket, and V. Mueller
astro-ph/9408099
Whither do the microlensing Brown Dwarfs rove?
The EROS and MACHO collaborations have reported observations of light curves of stars in the Large Magellanic Cloud that are compatible with gravitational microlensing by intervening massive objects, presumably Brown-Dwarf stars. The OGLE and MACHO teams have also seen similar events in the direction of the galactic Bu...
1994-08-31
2015-06-24
[ "astro-ph", "hep-ph" ]
A. de Rujula, G. Giudice, S. Mollerach and E. Roulet
astro-ph/9408101
Statistical Uncertainties in Temperature Diagnostics for Hot Coronal Plasma Using the ASCA SIS
Statistical uncertainties in determining the temperatures of hot (0.5 keV to 10 keV) coronal plasmas are investigated. The statistical precision of various spectral temperature diagnostics is established by analyzing synthetic ASCA Solid-state Imaging Spectrometer (SIS) CCD spectra. The diagnostics considered are the r...
1994-08-31
2009-10-22
[ "astro-ph" ]
Douglas A. Swartz, S. L. O'Dell, M.E. Sulkanen, and A.F. Tennant
astro-ph/9408100
An Extended Galactic Population of Low-Luminosity X-Ray Sources (CVs?) and the Diffuse X-Ray Background
Summary of abstract: The existence of a new population of yet unrecognized x-ray sources has been often suggested to resolve some pecularities in the properties of the x-ray background (XRB), and has recently been indicated by an analysis of resolved sources in deep ROSAT observations (Hasinger \etal 1993). We invest...
1994-08-31
2009-10-22
[ "astro-ph" ]
Eyal Maoz and Jonathan Grindlay
astro-ph/9408098
The Richness of the Globular Cluster System of NGC 3923: Clues to Elliptical Galaxy Formation
We present new data on the globular cluster system of the elliptical galaxy NGC 3923 which show that it has the most globular clusters per unit luminosity of any non-cluster elliptical yet observed, with $S_N=6.4 \pm1.4$. NGC 3923 is also among the brightest ellipticals outside of a galaxy cluster for which the number ...
1994-08-30
2009-10-22
[ "astro-ph" ]
S.E. Zepf, D. Geisler, and K.M. Ashman
astro-ph/9408096
The Density of 1-Jansky Sources Around Zwicky Clusters
In a recent paper by Rodrigues-Williams \& Hogan (RH94), a correlation between high-redshift, optically-selected QSOs and Zwicky clusters was reported at a very high significance level. Due to the fairly bright flux threshold of the cluster sample, these correlations cannot be interpreted as being due to an environment...
1994-08-30
2007-05-23
[ "astro-ph" ]
Stella Seitz and Peter Schneider
astro-ph/9408097
On the RMS Anisotropy at 7 degrees and 10 degrees Observed in the COBE-DMR Two Year Sky Maps
The frequency-independent RMS temperature fluctuations determined from the COBE-DMR two year sky maps are used to infer the parameter Q_{rms-PS}, which characterizes the normalization of power law models of primordial cosmological temperature anisotropy. In particular, a 'cross'-RMS statistic is used to determine Q_{rm...
1994-08-30
2007-05-23
[ "astro-ph" ]
A.J. Banday, K.M. Gorski, L. Tenorio, E.L. Wright, G.F. Smoot, C.H. Lineweaver, A. Kogut, G. Hinshaw, & C.L. Bennett
astro-ph/9408088
Quasar-galaxy associations
There is controversy about the measurement of statistical associations between bright quasars and faint, presumably foreground galaxies. We look at the distribution of galaxies around an unbiased sample of 63 bright, moderate redshift quasars using a new statistic based on the separation of the quasar and its nearest n...
1994-08-29
2015-06-24
[ "astro-ph" ]
P.A. Thomas, R.L. Webster and M.J. Drinkwater
astro-ph/9408092
Non-Linear Cluster Lens Reconstruction
We develop a method for general non-linear cluster lens reconstruction using the observable distortion of background galaxies. The distortion measures the combination $\gamma/(1-\kappa)$ of shear $\gamma$ and surface density $\kappa$. From this we obtain an expression for the gradient of $\log (1 - \kappa)$ in terms of...
1994-08-29
2009-10-22
[ "astro-ph" ]
Nick Kaiser
astro-ph/9408093
Primordial Non-Gaussian Signatures in the Sky
The presence of non-Gaussian features in the CMB radiation maps represents one of the most long-awaited clues in the search for the actual structure of the primordial radiation. These features could shed some light on the non trivial task of distinguishing the real source of the primeval perturbations leading to large ...
1994-08-29
2009-10-22
[ "astro-ph" ]
Alejandro Gangui (SISSA)
astro-ph/9408089
Gravitational instability in the strongly nonlinear regime: A study of various approximations
We study the development of gravitational instability in the strongly non-linear regime. For this purpose we use a number of statistical indicators such as filamentary statistics, spectrum of overdense/underdense regions and the void probability function, each of which probes a particular aspect of gravitational cluste...
1994-08-29
2015-06-24
[ "astro-ph" ]
B.S. Sathyaprakash, V. Sahni, D. Munshi, D. Pogosyan, A. L. Melott
astro-ph/9408095
Point Sources in the Cosmic Microwave Background?
Non-Gaussian imprints on the cosmic microwave background radiation (CBR) sky are within the grasp of current experiments. A clear non-Gaussian signature would be point-like sources. We have examined the nature of possible point sources that were tentatively identified in a recent high frequency CBR experiment with half...
1994-08-29
2009-09-25
[ "astro-ph" ]
Xiaochun Luo and J. Silk
astro-ph/9408091
The Long Period AM Her-like Cataclysmic Variable RXJ051541+0104.6
We report the discovery of a new catacysmic variable system, RXJ051541+0104.6. The optical spectrum has a blue continuum with superposed H~I and He~I and II emission lines. The soft X-ray spectrum is well fit with a 50~eV black body. The X-ray and optical data are suggestive of an AM~Herculis system. The X-ray light cu...
1994-08-29
2009-10-22
[ "astro-ph" ]
F. M. Walter, S. J. Wolk, and N. R. Adams (ESS Dept, SUNY Stony Brook)
astro-ph/9408090
Optical Radii of Galaxy Clusters
We analyze the density profiles and virial radii for a sample of 90 nearby clusters, using galaxies with available redshifts and positions. Each cluster has at least 20 redshifts measured within an Abell radius, and all the results come from galaxy sets of at least 20 members. Most of the density profiles of our cluste...
1994-08-29
2009-10-22
[ "astro-ph" ]
M. Girardi, A. Biviano, G. Giuricin, F. Mardirossian, and M. Mezzetti
astro-ph/9408094
Baryonic Dark Matter and the Diffuse Gamma Ray Background
We show that the baryonic gas content of the halo of our galaxy can be probed by performing a multipole expansion on the distribution of diffuse background gamma-ray emission. While the monopole moment (isotropic background) can be used to constrain the baryonic fraction of the halo gas, the quadrupole to monopole rati...
1994-08-29
2009-09-25
[ "astro-ph" ]
Xiaochun Luo and J. Silk
astro-ph/9408087
A search for the associations of distant radio-bright quasars with Abell clusters: an effect of gravitational amplification bias ?
The theory predicts that the effect of gravitational lensing by the matter associated with clusters of galaxies can magnify background sources, leading to an enhancement of source number density around foreground clusters of galaxies. We conduct a search for the associations of distant radio-bright quasars with Abell c...
1994-08-27
2015-06-24
[ "astro-ph" ]
Xiang-Ping Wu and Jinlin Han
astro-ph/9408086
Non-Parametric Dynamical Analysis of Globular Clusters: M15, 47~Tuc, NGC~362, and NGC~3201
We use radial velocities of member stars and cluster surface brightness profiles to non-parametrically determine the mass density profiles and isotropic phase-space distribution functions $f(E)$ for the globular clusters M15 (NGC7078), 47~Tuc (NGC104), NGC~362, and NGC~3201. Assuming isotropy and using the velocity dis...
1994-08-26
2009-10-22
[ "astro-ph" ]
Karl Gebhardt and Philippe Fischer
astro-ph/9408084
Parameter degeneracy in models of the quadruple lens system Q2237+0305
The geometry of the quadruple lens system Q2237+0305 is modeled with a simple astigmatic lens: a power-law mass distribution: m \propto r^\beta with an external shear \gamma. The image positions can be reproduced with an accuracy better than 0.01 arcsec for any 0.0 < \beta < 1.85 and the corresponding value of \gamma =...
1994-08-26
2009-10-22
[ "astro-ph" ]
Joachim Wambsganss and Bohdan Paczynski
astro-ph/9408085
Sky Subtraction with Fiber-Spectrographs
The sky subtraction performances of multi-fiber spectrographs are discussed, analysing in detail the case of the OPTOPUS system at the 3.6 meter ESO telescope at La Silla. A standard technique, based on flat-fields obtained with a uniformly illuminated screen on the dome, provides poor results. A new method has been de...
1994-08-26
2009-10-22
[ "astro-ph" ]
C. Lissandrini, S. Cristiani, F. La Franca
astro-ph/9408083
Deep Imaging of the Double Quasar 0957+561: New Constraints on H_0
We present new results from extremely deep, high-resolution images of the field around the double quasar QSO 0957+561. A possible gravitational arc system near the double quasar has recently been reported, which, if real, would set strong constraints on determinations of the Hubble constant from the time delay in the d...
1994-08-25
2009-10-22
[ "astro-ph" ]
H. Dahle, S.J. Maddox and Per B. Lilje
astro-ph/9408082
Arc Statistics with Realistic Cluster Potentials. II. Influence of Cluster Asymmetry and Substructure
We construct a sample of numerical models for clusters of galaxies and employ these to investigate their capability of imaging background sources into long arcs. Emphasis is laid on the statistics of these arcs. We study cross sections for arc length and length-to-width ratio and optical depths for these arc properties...
1994-08-24
2007-05-23
[ "astro-ph" ]
Matthias Bartelmann, Matthias Steinmetz, and Achim Weiss
astro-ph/9408080
The Cloud-in-Cloud Problem in the Press-Schechter Formalism of Hierarchical Structure Formation
The formalism by Press and Schechter (PS) is often used to infer number densities of virialized objects of mass M (e.g. quasars, galaxies, clusters of galaxies, etc.) from a count of initially overdense regions in a Gaussian density perturbation field. We reanalyze the PS-formalism by explicitly counting underdense reg...
1994-08-24
2009-10-22
[ "astro-ph" ]
K. Jedamzik
astro-ph/9408081
Baryon Number Transport in a Cosmic QCD-Phase Transition
We investigate the transport of baryon number across phase boundaries in a putative first order QCD-phase transition. Two independent phenomenological models are employed to estimate the baryon penetrability at the phase boundary: chromoelectric flux tube models; and an analogy to baryon-baryon coalescence in nuclear p...
1994-08-24
2009-10-22
[ "astro-ph" ]
K. Jedamzik and G.M. Fuller
astro-ph/9408079
Paramagnetic alignment of fractal grains
Paramagnetic alignment of fractal suprathermally rotating grains is discussed. It is shown that if the concentration of H$_{2}$formation sites is low and resurfacing is active, fractal structure of grains enhances their alignment. Studying the influence of grain surface physics and chemistry on the alignment we found t...
1994-08-23
2007-05-23
[ "astro-ph" ]
A. Lazarian
astro-ph/9408078
String Radiative Backreaction
We discuss radiative backreaction for global strings described by the Kalb-Ramond action with an analogous derivation to that for the point electron in classical electrodynamics. We show how local corrections to the equations of motion allow one to separate the self-field of the string from that of the radiation-field....
1994-08-22
2009-10-22
[ "astro-ph", "hep-ph", "hep-th" ]
R.A. Battye and E.P.S. Shellard
astro-ph/9408077
Self-Consistent Particle Acceleration in Active Galactic Nuclei
Adopting the hypothesis that the nonthermal emission of Active Galactic Nuclei (AGN) is primarily due to the acceleration of protons, we construct a simple model in which the interplay of acceleration and losses can be studied together with the formation of the emitted spectrum. The acceleration process is assumed to b...
1994-08-22
2008-02-03
[ "astro-ph" ]
A. Mastichiadis J. G. Kirk
astro-ph/9408076
Probing the Era of Galaxy Formation via TeV Gamma Ray Absorption by the Near Infrared Extragalactic Background
We present models of the extragalactic background light (EBL) based on several scenarios of galaxy formation and evolution. We have treated galaxy formation with the Press-Schecter approximation for both cold dark matter (CDM) and cold+hot dark matter (CHDM) models. Galaxy evolution has been treated by considering a va...
1994-08-21
2008-02-03
[ "astro-ph", "hep-ph" ]
Donn MacMinn and Joel R. Primack
astro-ph/9408075
Astrometric Plate Reduction with Orthogonal Functions and Milli-Arcseconds Accuracy in Deep Proper Motion Surveys
We have been doing a sample survey in UBV photometry and proper motions as part of an investigation of galactic structure and evolution. The programme is based on Schmidt plates (from OCA, Tautenburg, Palomar and ESO Schmidt telescopes) digitized with the MAMA machine (CAI, Paris). The high astrometric quality of the M...
1994-08-21
2007-05-23
[ "astro-ph" ]
Devendra Ojha and Olivier Bienayme
astro-ph/9408074
The Asymmetric Drift of the Thick Disk Population
We investigate the kinematics of the intermediate population using the photometric and astrometric sample surveys towards two opposite directions (galactic centre and anticentre) at intermediate latitude. A multivariate discriminant analysis (MDA) is used to distinguish the `Thick Disk' from other populations with the ...
1994-08-21
2007-05-23
[ "astro-ph" ]
Devendra Ojha, Annie C. Robin and Olivier Bienayme
astro-ph/9408073
Counts and Colours of Faint Stars in 5 Fields Near the North Galactic Pole
Faint star number counts in the photographic \jmag band and \bvcol colour distributions are presented for a 1.08 deg$^2$ field near the North Galactic Pole. Due to the excellent star/galaxy discrimination we count stars as faint as \jmag = 23. We compare the number counts and colour distributions in 5 adjacent fields n...
1994-08-19
2007-05-23
[ "astro-ph" ]
L. Infante
astro-ph/9408072
The Medium Redshift Clusters CL0017-20 and CL0500-24
We present magnitudes and redshifts of galaxies in the cluster of galaxies CL0017-20 and in the double cluster CL0500-24. Luminosity functions and velocity distributions have been derived. CL0017-20 possesses a virial mass of $2.9 \times 10^{14}$ M$_\odot$ and a \vmag band luminosity of $2.3 \pm 0.5 \times 10^{12}$ L$_...
1994-08-19
2007-05-23
[ "astro-ph" ]
L. Infante, P Fouque, G. Hertling, M.J. Way, E. Giraud and H. Quintana
astro-ph/9408071
The Clustering Properties of Faint Galaxies
The two-point angular correlation function of galaxies, \wte, has been computed from a new survey of faint galaxies covering a 2 deg$^2$ area near the North Galactic Pole. This survey, which is complete to limiting magnitudes \jmag=24 and \fmag=23, samples angular scales as large as $1\degpoint5$. Faint galaxies are fo...
1994-08-19
2009-10-22
[ "astro-ph" ]
L. Infante and C.J. Pritchet
astro-ph/9408070
Gaussian Statistics of the Cosmic Microwave Background: Correlation of Temperature Extrema In the COBE DMR Two-Year Sky Maps
We use the two-point correlation function of the extrema points (peaks and valleys) in the COBE Differential Microwave Radiometers (DMR) 2-year sky maps as a test for non-Gaussian temperature distribution in the cosmic microwave background anisotropy. A maximum likelihood analysis compares the DMR data to n=1 toy model...
1994-08-19
2011-05-10
[ "astro-ph" ]
A. Kogut, A.J. Banday, C.L. Bennett, G. Hinshaw, P.M. Lubin, and G.F. Smoot
astro-ph/9408064
The complex theory of gravitational lensing: Beltrami equation and cluster lensing
We introduce a new complex formalism to describe arclet fields in clusters of galaxies and derive the appropriate inversion techniques to find the related mass distribution of the lensing cluster. Applying the complex formalism to the statistics of lensed background sources shows that the mean of the axial ratios of lo...
1994-08-18
2007-05-23
[ "astro-ph" ]
T. Schramm, R. Kayser
astro-ph/9408065
Galaxy Formation in a Variety of Hierarchical Models
We predict the observable properties of the galaxy population in popular hierarchical models of galaxy formation. We employ a detailed semianalytic procedure which incorporates the formation and merging of dark matter halos, the shock heating and radiative cooling of gas, self-regulated star formation, the merging of g...
1994-08-18
2015-06-24
[ "astro-ph" ]
Jeremy S. Heyl, Shaun Cole, Carlos S. Frenk and Julio F. Navarro
astro-ph/9408067
The Assembly of Galaxies in a Hierarchically Clustering Universe
We study the formation of galaxies by using $N$-body/hydrodynamics simulations to investigate how baryons collect at the centre of dark matter halos. We treat the dark matter as a collisionless fluid and the baryons as an ideal gas. We include the effects of gravity, pressure gradients, hydrodynamical shocks, and radia...
1994-08-18
2015-06-24
[ "astro-ph" ]
Julio F. Navarro, Carlos S. Frenk, and Simon D.M. White
astro-ph/9408068
The Damping and Excitation of Galactic Warps by Dynamical Friction
We investigate the dynamical interaction of galactic warps with the surrounding dark matter halo, using analytic perturbation theory. A precessing warp induces a density wake in the collisionless dark matter, which acts back on the original warp, transferring energy and angular momentum between the warp and halo (dynam...
1994-08-18
2015-06-24
[ "astro-ph" ]
Robert W. Nelson and Scott Tremaine
astro-ph/9408069
Simulations of X-ray Clusters
We present simulations of the formation and evolution of galaxy clusters in the Cold Dark Matter cosmogony. Clusters with a wide range of mass were selected from previous N-body models, and were resimulated at higher resolution using a combined N-body/Smooth Particle Hydrodynamics code. The effects of radiative cooling...
1994-08-18
2015-06-24
[ "astro-ph" ]
Julio F. Navarro, Carlos S. Frenk, and Simon D.M. White
astro-ph/9408066
Interpreting Large Scale Structure Observations
The standard model of large scale structure is considered, in which the structure originates as a Gaussian adiabatic density perturbation with a nearly scale invariant spectrum. The basic theoretical tool of cosmological perturbation theory is described, as well as the possible origin of the density perturbation as a v...
1994-08-18
2007-05-23
[ "astro-ph", "hep-ph" ]
David H Lyth and Andrew R Liddle
astro-ph/9408057
A comparison of the evolution of the density field in perturbation theory and numerical simulations - II Counts in cells analysis
We present a detailed comparison of the predictions of perturbation theory for the averaged J-point correlation functions, $\xibar_J$, with the results of numerical simulations of gravitational clustering. We have carried out a systematic analysis of this method using ensembles of simulations with different numbers of ...
1994-08-17
2015-06-24
[ "astro-ph" ]
C.M.Baugh, E. Gaztanaga and G.Efstathiou
astro-ph/9408063
Duration Distributions of Bright and Dim BATSE Gamma-Ray Bursts
We have measured the T90 and T50 durations of bright and dim gamma-ray bursts (GRBs) detected by the Compton Gamma Ray Observatory's Burst and Transient Source Experiment (BATSE). The T90 (T50) duration is defined as the interval over which 5\% (25\%) to 95\% (75\%) of the burst counts accumulate. Out of 775 bursts obs...
1994-08-17
2009-10-22
[ "astro-ph" ]
J.P. Norris (NASA/GSFC), J.T. Bonnell (NASA/USRA), R.J. Nemiroff (NASA/GMU), J. D. Scargle (NASA/AMES), C. Kouveliotou (NASA/USRA), W.S. Paciesas (NASA/UAH), C. A. Meegan (NASA/MSFC), G.J. Fishman (NASA/MSFC)
astro-ph/9408061
A Merger Model and Globular Cluster Formation
We propose a self-consistent model for globular cluster formation in, but not limited to, our Galaxy, based on the merger model of Mathews and Schramm (1993). Stars and star clusters form in bursts at the merging interfaces as protogalactic clouds collide. We describe the formation of those star clusters with a simple ...
1994-08-17
2009-10-22
[ "astro-ph" ]
Sangjin Lee, David N. Schramm and Grant J. Mathews
astro-ph/9408059
Stellar Models with Microscopic Diffusion and Rotational Mixing II: Application to Open Clusters
Stellar models with masses ranging from 0.5 to $1.3~M_\odot$ were constructed in order to compare to young cluster observations of Li and of rotation velocities. The amount of Li depletion in cool stars is sensitive to the amount of overshoot at the base of the surface convection zone, and the exact metallicity of the ...
1994-08-17
2009-10-22
[ "astro-ph" ]
Brian Chaboyer, P. Demarque and M.H. Pinsonneault
astro-ph/9408054
Hydrodynamics of Coalescing Binary Neutron Stars: Ellipsoidal Treatment
We employ an approximate treatment of dissipative hydrodynamics in three dimensions to study the coalescence of binary neutron stars driven by the emission of gravitational waves. The stars are modeled as compressible ellipsoids obeying a polytropic equation of state; all internal fluid velocities are assumed to be lin...
1994-08-17
2009-10-22
[ "astro-ph" ]
Dong Lai and Stu Shapiro
astro-ph/9408053
Gravitational Radiation from Rapidly Rotating Nascent Neutron Stars
We study the secular evolution and gravitational wave signature of a newly-formed, rapidly rotating neutron star. The neutron star may arise from core collapse in a massive star or from the accretion-induced collapse of a white dwarf. After a brief dynamical phase, the nascent neutron star settles into an axisymmetric,...
1994-08-17
2009-10-22
[ "astro-ph" ]
Dong Lai and Stu Shapiro
astro-ph/9408058
Stellar Models with Microscopic Diffusion and Rotational Mixing I: Application to the Sun
The Yale stellar evolution code has been modified to include the combined effects of diffusion and rotational mixing on $^1$H, $^4$He and the trace elements $^3$He, $^6$Li, $^7$Li, and $^9$Be. The interaction between rotational mixing and diffusion is studied by calculating a number of calibrated solar models. The rota...
1994-08-17
2009-10-22
[ "astro-ph" ]
Brian Chaboyer, P. Demarque and M.H. Pinsonneault
astro-ph/9408055
Resolving the Question of Time for Semiclassical Gravity
Hamilton-Jacobi theory provides a natural starting point for a covariant description of the gravitational field. Using a spatial gradient expansion, one may solve for the phase of the wavefunction by using a line-integral in superspace. Each contour of integration corresponds to a particular choice of the time-hypersur...
1994-08-17
2007-05-23
[ "astro-ph", "gr-qc", "hep-ph" ]
D.S. Salopek
astro-ph/9408062
The Deuterium Abundance and Nucleocosmochronology
We examine galactic chemical evolution models which reproduce the present-day and pre-solar values of deuterium starting with a primordial value which is consistent with a baryon-to-photon ratio of $3 \times 10^{-10}$. We consider various galactic chemical evolution models to determine the viability of significant deut...
1994-08-17
2009-10-22
[ "astro-ph" ]
Sean Thomas Scully and Keith A. Olive
astro-ph/9408060
Microlensing Events: End of the Dark Halo?
I obtain an upper limit for the optical depth to microlensing toward Baade's Window of $3\times 10^{-6}$ by assuming that all of the mass of the Galaxy interior to the Sun (and not in the bulge) is in a disk. The exponential scale height of the disk is left as a completely arbitrary function of radius and is varied to ...
1994-08-17
2007-05-23
[ "astro-ph" ]
Andrew Gould
astro-ph/9408056
Effect of Adiabatic Deceleration on the Focused Transport of Solar Cosmic Rays
In the framework of focused transport theory, adiabatic deceleration arises from adiabatic focusing in the solar wind frame and from differential solar wind convection. An explicit formula is given for the deceleration of individual particles as a function of the pitch angle. Deceleration and other first-order effects ...
1994-08-17
2009-10-22
[ "astro-ph" ]
D. Ruffolo
astro-ph/9408050
Steps towards Nonlinear Cluster Inversion Through Gravitational Distortions. II. Generalization of the Kaiser & Squires Method
The weak distortions of high-redshift galaxies caused by gravitational light deflection near clusters of galaxies can be used to reconstruct the projected (two-dimensional) surface mass density of intermediate redshift clusters. This technique, pioneered by Tyson, Valdes & Wenk, and Kaiser & Squires, is reconsidered in...
1994-08-16
2007-05-23
[ "astro-ph" ]
Carolin Seitz, Peter Schneider
astro-ph/9408052
A New Method for Finding Clusters of Galaxies at z>1
At large redshifts, a cluster or group may be too distant for the galaxies within the cluster to be detected individually. However, the light from these ``undetected'' galaxies still modulates the surface brightness of the background sky. Clusters can appear as 10"-1.5' sized fluctuations in the surface brightness of t...
1994-08-16
2007-05-23
[ "astro-ph" ]
J.J. Dalcanton
astro-ph/9408051
Super-Eddington Radiation Transfer in Soft Gamma Repeaters
Bursts from soft gamma repeaters have been shown to be super-Eddington by a factor of 1000 and have been persuasively associated with compact objects. Here, a model of super-Eddington radiation transfer on the surface of a strongly magnetic ($\geq 10^{13}$ gauss) neutron star is studied and related to the observational...
1994-08-16
2009-10-22
[ "astro-ph" ]
Andrew Ulmer
astro-ph/9408044
Primordial Spectral Indices from Generalized Einstein Theories
Primordial spectral indices are calculated to second order in slow-roll parameters for three closely-related models of inflation, all of which contain a scalar field non-minimally coupled to the Ricci curvature scalar. In most cases, $n_s$ may be written as a function of the non-minimal curvature coupling strength $\xi...
1994-08-15
2010-11-01
[ "astro-ph", "gr-qc", "hep-ph" ]
David Kaiser
astro-ph/9408049
Gross Spectral Differences between Bright and Dim Gamma-Ray Bursts
We find that dim gamma-ray bursts (GRBs) are softer than bright GRBs, as indicated on average by data from the Burst and Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory. We show that this correlation is statistically significant with respect to variations due to random differences between...
1994-08-15
2009-10-22
[ "astro-ph" ]
R.J. Nemiroff (NASA/GMU), J.P. Norris (NASA/GSFC), J.T. Bonnell (NASA/USRA), W.A.D.T. Wickramasinghe (UPenn), C. Kouveliotou (NASA/USRA), W.S. Paciesas (NASA/UAH), G.J. Fishman (NASA/MSFC), C.A. Meegan (NASA/MSFC)
astro-ph/9408048
X-ray Variability and Period Determinations in the Eclipsing Polar DP Leo
An analysis of ROSAT observations for the eclipsing magnetic cataclysmic binary DP Leo provides constraints on the origin, size, temperature, variability and structure of the soft X-ray emission region on the surface of the white dwarf. These data, when combined with prior observations, show a progression of approximat...
1994-08-15
2009-10-22
[ "astro-ph" ]
C.R. Robinson and F.A. Cordova
astro-ph/9408047
Microlensing Events of the LMC are Better Explained by Stars within the LMC Than by Machos
The recently reported microlensing events of the LMC have caused much excitement, and have been interpreted as due to `dark objects' (MACHOs) in the halo of our Galaxy. It is shown here that the stars within the LMC play a dominant role as gravitational lenses and can indeed account for the observed events. The MACHO e...
1994-08-15
2009-10-22
[ "astro-ph" ]
Kailash C. Sahu
astro-ph/9408046
Likelihood Analysis of Large-Scale Flows
We apply a likelihood analysis to the data of \markcite{Lauer \& Postman 1994} With $P(k)$ parametrized by $(\sigma_8, \Gamma)$, the likelihood function peaks at $\sigma_8\simeq0.3$, $\Gamma\lesssim0.025$, indicating at face value very strong large-scale power, though at a level incompatible with COBE\@. There is, howe...
1994-08-15
2009-10-22
[ "astro-ph" ]
A. Jaffe and N. Kaiser (CITA)
astro-ph/9408043
Velocity Bias in MS1224+20
Velocity bias offers a single parameter ($b_v$) description of the likely segregation of mass and light in a galaxy cluster. The relation between the projected mass profile and the light profile, normalized by the virial $M/L$, is presented as a function of $b_v\equiv\sigma_\ell/\sigma_\rho$, the ratio of the RMS veloc...
1994-08-15
2009-10-22
[ "astro-ph" ]
R. G. Carlberg
astro-ph/9408045
Bias Minimisation in POTENT
Much current interest in cosmology has revolved around the peculiar velocity field of galaxies. Many methods have been proposed to derive this, probably the most prominent being POTENT (Dekel et al. 1990). However, this is prone to many forms of systematic error or bias. Here, we examine some of the methods currently u...
1994-08-15
2007-05-23
[ "astro-ph" ]
A. Newsam, J.F.L. Simmons, M.A. Hendry
astro-ph/9408042
Detection of Compact Ultraviolet Nuclear Emission in LINER Galaxies
Low-ionization nuclear emission-line regions (LINERs), which exist in a large fraction of galaxies, may be the least luminous manifestation of quasar activity. The nature of LINERs has, however, remained controversial because an AGN-like nonstellar continuum source has not been directly observed in them. We report the ...
1994-08-14
2008-11-26
[ "astro-ph" ]
Dan Maoz, Alexei V. Filippenko, Luis C. Ho, Hans-Walter Rix, John N. Bahcall, Donald P. Schneider, and F. Duccio Macchetto
astro-ph/9408041
Magnetic Merging in Colliding Flux Tubes
We develop an analytical theory of reconnection between colliding, twisted magnetic flux tubes. Our analysis is restricted to direct collisions between parallel tubes and is based on the collision dynamics worked out by Bogdan (1984). We show that there is a range of collision velocities for which neutral point reconne...
1994-08-14
2009-10-22
[ "astro-ph" ]
Ellen G. Zweibel & James E. Rhoads
astro-ph/9408040
Semi-analytic Continuum Spectra of Type II Supernovae and the Expanding Photosphere Method of Distance Determination
We extend the approximate radiative transfer analysis of Hershkowitz, Linder, and Wagoner (1986) to a more general class of supernova model atmospheres, using a simple fit to the effective continuum opacity produced by lines (Wagoner, Perez, and Vasu 1991). At the low densities considered, the populations of the excite...
1994-08-14
2008-02-03
[ "astro-ph" ]
M.J. Montes & R.V. Wagoner
astro-ph/9408039
BD+30 3639: The Infrared Spectrum During Post-AGB Stellar Evolution
We present a radiative-transfer calculation which reproduces the infrared spectrum of the planetary nebula BD~+30$^{\circ}$3639. We calculate the transfer process through absorption and scattering in a spherical-symmetric multi-grain dust shell. The emission of transiently heated particles is taken into account, as wel...
1994-08-13
2015-06-24
[ "astro-ph" ]
R. Siebenmorgen, A.A. Zijlstra and E. Kruegel
astro-ph/9408037
CMB Maps at 0.5 degree Resolution I: Full-Sky Simulations and Basic Results
We have simulated full-sky maps of the Cosmic Microwave Background (CMB) anisotropy expected from Cold Dark Matter (CDM) models at 0.5 and 1.0 degree angular resolution. Statistical properties of the maps are presented as a function of sky coverage, angular resolution, and instrument noise, and the implications of thes...
1994-08-12
2007-05-23
[ "astro-ph" ]
G. Hinshaw, C.L. Bennett, and A. Kogut
astro-ph/9408038
CMB Maps at 0.5 Degree Resolution II: Unresolved Features
High-contrast peaks in the cosmic microwave background (CMB) anisotropy can appear as unresolved sources to observers. We fit simulated CMB maps generated with a cold dark matter model to a set of unresolved features at instrumental resolution 0.5 degrees to 1.5 degrees and present the integral density per steradian n(...
1994-08-12
2007-05-23
[ "astro-ph" ]
A. Kogut, G. Hinshaw, and C.L. Bennett
astro-ph/9408036
Observations of the Cosmic Microwave Background
The properties of the cosmic microwave background radiation provide unique constraints on cosmological models, i.e. on the content, history, and evolution of the Universe. I discuss the latest measurements of the spectral and spatial properties of the cosmic microwave background radiation. Recent measurements from NASA...
1994-08-12
2009-10-22
[ "astro-ph" ]
C. L. Bennett
astro-ph/9408035
Current Status of Axion Cosmology
We review the current status of axion cosmology in the light of recent work. We conclude that in the standard scenario, in which a global string network forms at the Peccei-Quinn phase transition, the largest contribution to the axion density is from loops, even when uncertainties in the nature of the QCD phase transit...
1994-08-12
2007-05-23
[ "astro-ph", "hep-ph" ]
R.A. Battye and E.P.S. Shellard
astro-ph/9408034
Cosmic Strings and Cosmic Variance
By using a simple analytical model based on counting random multiple impulses inflicted on photons by a network of cosmic strings we show how to construct the general q-point temperature correlation function of the Cosmic Microwave Background radiation. Our analysis is sensible specially for large angular scales where ...
1994-08-11
2011-05-10
[ "astro-ph", "hep-ph" ]
Alejandro Gangui (SISSA-Trieste) and Leandros Perivolaropoulos (Harvard CfA)
astro-ph/9408033
Anticorrelated CN and CH Variations on the 47 Tucanae Main-Sequence Turnoff
Observations of CN and CH band strengths among a random sample of main-sequence turn-off stars (+3.9 < MV < +4.6) in the globular cluster 47 Tuc (NGC 104, C0021-723) were made with the CTIO Argus fiber spectrograph for the purpose of determining the ratio of CN-strong to CN-weak stars and investigating the behavior of ...
1994-08-11
2009-10-22
[ "astro-ph" ]
M. M. Briley, J. E. Hesser, R. A. Bell, M. Bolte and G. H. Smith
astro-ph/9408030
Detecting Bimodality in Astronomical Datasets
We discuss statistical techniques for detecting and quantifying bimodality in astronomical datasets. We concentrate on the KMM algorithm, which estimates the statistical significance of bimodality in such datasets and objectively partitions data into sub-populations. By simulating bimodal distributions with a range of ...
1994-08-10
2009-10-22
[ "astro-ph" ]
Keith M. Ashman, Christina M. Bird, and Steven E. Zepf
astro-ph/9408032
Macho Parallaxes From A Single Satellite
Massive Compact Objects (Machos) are currently being discovered at substantially higher rates than would be expected from standard models of known stellar populations. To determine whether they are due to non-standard distri- butions of known populations or to a heretofore unknown (`dark') population, one must acquire ...
1994-08-10
2009-10-22
[ "astro-ph" ]
Andrew Gould
astro-ph/9408031
A Survey of Galaxy Redshifts from Low-Resolution Slitless Spectra: Suggestion of Large-Scale Structures at Z ~0.1
We have conducted a galaxy survey based on low-resolution slitless spectra taken from the automated CFHT-Laval survey. We present redshift distributions for 522 galaxies distributed in 4 distinct regions of the sky. Redshifts are determined from the shifted positions of the 4000 A. stellar break using an automated brea...
1994-08-10
2015-06-24
[ "astro-ph" ]
M. Beauchemin and E.F. Borra