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astro-ph/9509054
A Theory of Non-Local Mixing Length Convection. III. Comparing Theory and Numerical Experiment
We solve the nonlocal convection equations. The solutions for four model problems are compared with results of GSPH simulations. In each case we test two closure schemes: 1) where third moments are defined by the diffusion approximation; and 2) where the full third moment equations are used and fourth moments are defin...
1995-09-08
2015-06-24
[ "astro-ph" ]
Scott Grossman (Northwestern University)
astro-ph/9509049
Warm Inflation
Assuming a first order phase transition during inflation, a model scenario is described which does not require a tiny coupling constant. Thermal equilibrium is closely maintained as inflation commences. No large scale reheating is necessary. Solutions for $N> 70$ are found for any $\delta \rho / \rho$ in the range $10^...
1995-09-08
2008-11-26
[ "astro-ph", "hep-ph" ]
Arjun Berera (Penn State)
astro-ph/9509039
Medium Resolution Near Infrared (2.15micron--2.35micron) Spectroscopy of Late-type Main Sequence stars
We present an atlas of moderate resolution ($\lambda/\Delta\lambda\sim$1380) 2.15~\micron\ to 2.39~\micron\ spectra of 33 luminosity class V stars of spectral type F3 to M6 in the MK classification system. We find that the equivalent widths of several spectral features vary significantly with temperature and typically ...
1995-09-07
2009-10-28
[ "astro-ph" ]
B. Ali, John S. Carr, D. L. DePoy, Jay A. Frogel & K. Sellgren
astro-ph/9509047
Loop Corrections in Non-Linear Cosmological Perturbation Theory
Using a diagrammatic approach to Eulerian perturbation theory, we analytically calculate the variance and skewness of the density and velocity divergence induced by gravitational evolution from Gaussian initial conditions, including corrections *beyond* leading order. Except for the power spectrum, previous calculation...
1995-09-07
2011-09-30
[ "astro-ph" ]
Roman Scoccimarro and Joshua Frieman (Fermilab and Univ. of Chicago)
astro-ph/9509044
The Statistics of Nearly On-Axis Gravitational Lensing Events
A small volume of space, nearly on-axis behind a gravitational lens with respect to a given source, will receive a greatly increased radiation flux. In the idealized case of a point mass lens acting on a point source in complete isolation, the volume will approach zero only as the flux tends to infinity; in fact, the v...
1995-09-07
2011-04-12
[ "astro-ph" ]
Yun Wang (Fermilab)
astro-ph/9509040
Variations of the Selective Extinction Across the Galactic Bulge - Implications for the Galactic Bar
We propose a new method to investigate the coefficient of the selective extinction, based on two band photometry. This method uses red clump stars as a means to construct the reddening curve. We apply this method to the OGLE color-magnitude diagrams to investigate the variations of the selective extinction towards vari...
1995-09-07
2009-10-28
[ "astro-ph" ]
P. R. Wozniak and K. Z. Stanek
astro-ph/9509043
The Angular Two Point Correlation Function for the FIRST Radio Survey - Initial Results
The angular two-point correlation function is calculated for the first 300 square degrees of the FIRST radio survey. Results for various subsamples are also obtained. Double-lobed sources are shown to have a higher clustering amplitude than the sample as a whole. Small differences in the correlation function from one r...
1995-09-07
2008-02-03
[ "astro-ph" ]
C.M.Cress, D.J.Helfand, R.H.Becker, R.L.White, M.D.Gregg
astro-ph/9509046
Toward a Unified View of Black Hole High Energy States
We present here a review of high energy (> 1 keV) observations of seven black hole candidates, six of which have estimated masses. In this review we focus on two parameters of interest: the ratio of ``non-thermal" to total luminosity as a function of the total luminosity divided by the Eddington luminosity, and the roo...
1995-09-07
2009-10-28
[ "astro-ph" ]
Michael A. Nowak (JILA)
astro-ph/9509035
CMB Anisotropies, Large-Scale Structure and the Future
We are now beginning to learn detailed information about cosmological parameters from the shapes of the matter and radiation power spectra, together with their relative normalization. As more high quality data are gathered from galaxy surveys and from microwave anisotropies, the range of allowed models is expected to g...
1995-09-07
2007-05-23
[ "astro-ph" ]
Douglas Scott
astro-ph/9509042
Statistics of Extreme Gravitational Lensing Events. I.The Zero Shear Case
For a given source and lens pair, there is a thin on-axis tube-like volume behind the lens in which the radiation flux from the source is greatly increased due to gravitational lensing. Any objects (such as dust grains) which pass through such a thin tube will experience strong bursts of radiation, i.e., Extreme Gravit...
1995-09-07
2009-10-28
[ "astro-ph" ]
Yun Wang and Edwin L. Turner
astro-ph/9509037
The Observational Appearance of Slim Accretion Disks
We reexamine the hypothesis that the optical/UV/soft X-ray continuum of Active Galactic Nuclei is thermal emission from an accretion disk. Previous studies have shown that fitting the spectra with the standard, optically thick and geometrically thin accretion disk models often led to luminosities which contradict the b...
1995-09-07
2009-10-28
[ "astro-ph" ]
Ewa Szuszkiewicz (SISSA), Matthew A. Malkan (ULCA), Marek A. Abramowicz (Goeteborg University)
astro-ph/9509036
The internal dynamics of very flattened normal galaxies: Stellar distribution functions for NGC 4697
Using the photometry and the kinematic data, part of which acquired with the NTT, we constructed a 2-integral and a 3-integral distribution function for NGC 4697. We detected a nuclear dust lane at $3.4''$ or 0.4 kpc from the centre. A comparison of the Lucy-deprojection method and the multi-gaussian expansion method s...
1995-09-07
2007-05-23
[ "astro-ph" ]
H. Dejonghe, V. De Bruyne, P. Vauterin and W.W. Zeilinger
astro-ph/9509045
The Wiener-Filtered COBE DMR Data and Predictions for the Tenerife Experiment
We apply a Wiener filter to the two-year COBE DMR data. The resulting sky map has significantly reduced noise levels compared to the raw data: the most prominent hot and cold spots are significant at the 4-sigma level. Furthermore, the entire covariance matrix of the errors in the filtered sky map is known, and it is t...
1995-09-07
2009-10-28
[ "astro-ph" ]
Emory F. Bunn, Yehuda Hoffman, and Joseph Silk
astro-ph/9509038
Starbursts and Star Clusters in the Ultraviolet
Hubble Space Telescope ultraviolet (UV) images of nine starburst galaxies reveal them to be highly irregular, even after excluding compact sources (clusters and resolved stars). Most (7/9) are found to have a similar intrinsic effective surface brightnesses, suggesting that a negative feedback mechanism is setting an u...
1995-09-07
2009-10-28
[ "astro-ph" ]
G.R. Meurer, T.M. Heckman, C. Leitherer, A. Kinney, C. Robert and D.R. Garnett
astro-ph/9509048
The origin of soft X-rays in luminous AGN
We predict that the UV bump spectrum of quasars extends into the soft X-ray range with a steep power law. For radio-louds, the spectral index is alpha_s ~ 1.7 (S_nu = S_o nu^-alpha), and for radio-quiets it should be somewhat steeper alpha_s >~ 1.7. The prediction is based on a simple scenario in which all quasars, rad...
1995-09-07
2007-05-23
[ "astro-ph" ]
K. Mannheim, M. Schulte, and J. Rachen
astro-ph/9509041
Strange matter and its stability in presence of magnetic field
We study the effect of a magnetic field on the interacting quark matter and apply to strange star. We considere the low temperature approximation to strange matter. We find that the interacting strange quark matter is more stable compare to free quark gas in presence of strong external magnetic field with zero and fini...
1995-09-07
2008-02-03
[ "astro-ph" ]
Pradip K Sahu
astro-ph/9509034
Galaxy Cluster Virial Masses and Omega
To re-examine the rich cluster $\Omega$ value the CNOC Cluster Survey has observed 16 high X-ray luminosity clusters in the redshift range 0.17 to 0.55, obtaining approximately 2600 velocities in their fields. Directly adding all the K and evolution corrected $r$ band light to $M_r(0)=-18.5$, about $0.2L_\ast$, and cor...
1995-09-06
2009-10-28
[ "astro-ph" ]
Carlberg, Yee, Ellingson, Abraham, Gravel, Morris & Pritchet
astro-ph/9509028
HST and MERLIN Observations of the Jet in 3C273
We present red and blue images of the jet of the quasar 3C273 obtained with the WFPC2 on the Hubble Space Telescope as well as a new radio map made with the MERLIN array. The images are of significantly better quality than that of previous data. The two maps are aligned to an accuracy of 0.020$''$; this accuracy is ach...
1995-09-06
2009-10-28
[ "astro-ph" ]
J. N. Bahcall, S. Kirhakos, and D. P. Schneider, R. J. Davis, T. W. B. Muxlow, S. T. Garrington, R. G. Conway, and S. C. Unwin
astro-ph/9509029
Effect of Sub-Structure in Clusters on the Local Weak-Shear Field
Weak shear maps of the outer regions of clusters have been successfully used to map the distribution of mass at large radii. The effects of substructure in clusters on such reconstructions of the total mass have not been systematically studied. We propose a new method to study the effect of perturbers (bright cluster g...
1995-09-06
2007-05-23
[ "astro-ph" ]
Priyamvada Natarajan and Jean-Paul Kneib
astro-ph/9509030
The Merging History of the Milky Way
The age distribution, and chemical elemental abundances, of stars in the halo of the Milky Way provide constraints on theories of galaxy formation. As one specific example, the accretion of satellite galaxies similar to the present retinue of dwarf spheroidals (dSphs) would provide an observable metal-poor, intermediat...
1995-09-06
2015-06-24
[ "astro-ph" ]
M. Unavane, R.F.G. Wyse, G.F. Gilmore
astro-ph/9509033
Aspects of Scaling in Gravitational Clustering
The scaling ansatz of Hamilton et al. effectively extends the idea of self-similar scaling to initial power spectra of any generic shape. Applications of this ansatz have provided a semi-empirical analytical description of gravitational clustering which is extremely useful. This contribution examines the two theoretica...
1995-09-06
2007-05-23
[ "astro-ph" ]
Bhuvnesh Jain
astro-ph/9509027
Formation of MACHO-Primordial Black Holes in Inflationary Cosmology
As a nonbaryonic explanation of massive compact halo objects, a phenomenological model is presented which predicts formation of primordial black holes at a desired mass scale. The required feature of initial density fluctuation is realized making use of the primordially isocurvature fluctuation generated in an inflatio...
1995-09-06
2011-05-23
[ "astro-ph" ]
Jun'ichi Yokoyama (YITP Uji Research Center, Kyoto U.)
astro-ph/9509032
Wavelet Space-Scale-Decomposition Analysis of QSO's Ly$\alpha$ Absorption Lines: Spectrum of Density Perturbations
A method for measuring the spectrum of a density field by a discrete wavelet space-scale decomposition (SSD) has been studied. We show how the power spectrum can effectively be described by the father function coefficients (FFC) of the wavelet SSD. We demonstrate that the features of the spectrum, such as the magnitude...
1995-09-06
2007-05-23
[ "astro-ph" ]
Jesus Pando and Li-Zhi Fang
astro-ph/9509031
The Apparently Normal Galaxy Hosts for Two Luminous Quasars
HST images (with WFPC2) of PHL~909\ ($z = 0.171$) and PG~0052$+$251\ ($z = 0.155$) show that these luminous radio-quiet quasars each occur in an apparently normal host galaxy. The host galaxy of PHL~909 is an elliptical galaxy ($\sim$ E4) and the host of PG~0052$+$251 is a spiral ($\sim$~Sb). Both host galaxies are sev...
1995-09-06
2016-08-30
[ "astro-ph" ]
John N. Bahcall, Sofia Kirhakos, and Donald P. Schneider
astro-ph/9509020
Identification of the soft X-ray excess in Cygnus X-1 with disc emission
We present results of a study of the soft X-ray excess in the black hole candidate Cygnus X-1 made with the {\it Rosat PSPC}, using observations taken during persistent emission at orbital phases close to 0.5. The soft excess can be well fitted as a blackbody with temperature $\rm {kT_{bb}}$ = $\rm {0.13\pm 0.02}$ keV....
1995-09-05
2007-05-23
[ "astro-ph" ]
M. Balucinska-Church, T. Belloni, M. J. Church and G. Hasinger
astro-ph/9509021
Observations of the X-ray Nova GRO~J0422+32: II: Optical Spectra Approaching Quiescence
We present results obtained from a series of 5~\AA\ resolution spectra of the X-ray Nova GRO~J0422+32 obtained in 1993~October, when the system was approximately 2 magnitudes above quiescence, with ${\rm R \sim 19}$. The data were obtained in an effort to measure the orbital radial velocity curve of the secondary, but ...
1995-09-05
2009-10-28
[ "astro-ph" ]
Michael R. Garcia, Paul J. Callanan, Jeffrey E. McClintock, Ping Zhao
astro-ph/9509024
Formation and Radiation Acceleration of Pair Plasmoids Near Galactic Black Holes
We study quantitatively the formation and radiation acceleration of electron-positron pair plasmoids produced by photon-photon collisions near Galactic black holes (GBHs). The terminal ejecta velocity is found to be completely determined by the total disk luminosity, proton loading factor and disk size, with no depende...
1995-09-05
2009-10-28
[ "astro-ph" ]
Hui Li (LANL) & Edison P. Liang (Rice University)
astro-ph/9509018
Dynamics of Subcritical Bubbles in First Order Phase Transition
We derivate the Langevin and the Fokker-Planck equations for the radius of $O(3)$-symmetric subcritical bubbles as a phenomenological model to treat thermal fluctuation. The effect of thermal noise on subcritical bubbles is examined. We find that the fluctuation-dissipation relation holds and that in the high temperatu...
1995-09-05
2009-10-28
[ "astro-ph", "hep-ph" ]
Tetsuya Shiromizu, Masahiro Morikawa and Jun'ichi Yokoyama
astro-ph/9509023
EGRET Observations of Gamma Rays from Point Sources with Galactic Latitude +10(degrees) < b < +40(degrees)
The EGRET instrument aboard the Compton Gamma Ray Observatory (CGRO) has completed the first all-sky survey in high-energy gamma rays and has repeatedly viewed selected portions of the sky. Analysis of the region with galactic latitude $+10\arcdeg < b < +40\arcdeg$ indicates the presence of nineteen point sources, incl...
1995-09-05
2009-10-28
[ "astro-ph" ]
P. L. Nolan (Stanford University) et al
astro-ph/9509025
Astrophysical signals of P and T violation by gravity
We study the observational consequences of the leading order P and T violating gauge invariant graviton-photon interactions. Such interactions give rise to gravitational birefringence - the velocity of light signals depends upon their polarisation, which is absent in Einstein's gravity. Using experimentally established...
1995-09-05
2007-05-23
[ "astro-ph" ]
A.R. Prasanna and Subhendra Mohanty
astro-ph/9509022
Cerenkov radiation by charged particles in an external gravitational field
Charged particles in the geodesic trajectory of an external gravitational field do not emit electromagnetic radiation. This is expected from the application of the equivalence principle. We show here that charged particles propagating in an external gravitational field with non-zero components of the Ricci tensor can e...
1995-09-05
2009-10-28
[ "astro-ph" ]
Anshu Gupta, Subhendra Mohanty and Manoj K. Samal
astro-ph/9509019
Weak Gravitational Lensing: Current Status and Future Prospects
In this review I will describe progress that has been made in determining masses of galaxy clusters using `weak lensing' and how this technique my be applied in the future to determine the dark matter distribution both on supercluster scales and on the scale of galaxy haloes.
1995-09-05
2007-05-23
[ "astro-ph" ]
Nick Kaiser (CITA, Toronto; on leave at AAO, Sydney)
astro-ph/9509013
Faint Blue Galaxies as a Probe of the X-ray Background at High Redshift
We present a formalism describing the physical content of cross-correlation functions between a diffuse background and a population of discrete sources. The formalism is used to interpret cross-correlation signals between the unresolved X-ray background and a galaxy population resolved to high redshift in another spect...
1995-09-04
2015-06-24
[ "astro-ph" ]
M.A. Treyer, O. Lahav
astro-ph/9509017
The Great Circle Camera: A New Drift Scanning Instrument
We discuss the design, construction, and use of a new class of scanning camera that eliminates a critical limitation of standard CCD drift-scan observations. A standard scan, which involves no correction for the differential drift rates and curved stellar paths across the field-of-view, suffers from severe image degrad...
1995-09-04
2009-10-28
[ "astro-ph" ]
Dennis Zaritsky (UCO/Lick Obs., UCSC), Stephen A. Shectman (Carnegie Obs.), and Gregory Bredthauer (Carnegie Obs.)
astro-ph/9509015
The discovery of a high redshift type 2 QSO
We report the discovery of a high redshift, narrow emission-line galaxy identified in the optical follow-up of deep ROSAT fields. The object has a redshift of z=2.35 and its narrow emission lines together with its high optical and X-ray luminosity imply that this is a rare example of a type 2 QSO. The intrinsic X-ray a...
1995-09-04
2007-05-23
[ "astro-ph" ]
O. Almaini, B.J. Boyle, R.E. Griffiths, T. Shanks, G.C. Stewart, I. Georgantopoulos
astro-ph/9509012
Global Aspects of Elliptical Instability in Tidally Distorted Accretion Disks
Tidally distorted accretion disks in binary star systems are subject to a local hydrodynamic instability which excites $m=1$ internal waves. This instability is three dimensional and approximately incompressible. We study the global aspects of this local instability using equations derived under the shearing sheet appr...
1995-09-04
2009-10-28
[ "astro-ph" ]
Dongsu Ryu, Jeremy Goodman, and Ethan T. Vishniac
astro-ph/9509014
Applications of Minkowski Functionals to the Statistical Analysis of Dark Matter Models
A new method for the statistical analysis of 3D point processes, based on the family of Minkowski functionals, is explained and applied to modelled galaxy distributions generated by a toy-model and cosmological simulations of the large-scale structure in the Universe. These measures are sensitive to both, geometrical a...
1995-09-04
2007-05-23
[ "astro-ph" ]
Michael Platzoeder and Thomas Buchert
astro-ph/9509011
Prominence and flare fine structure from cross-field thermal conduction
Thermal conduction across a magnetic field is strongly suppressed compared with conduction along the field. However, if a flare is heated by a highly filamented beam directed along the field, then the array of heated cells in a cross-section of the flare will result in both small spatial scales (with consequently large...
1995-09-04
2016-08-30
[ "astro-ph" ]
Norman Gray and John C Brown (University of Glasgow)
astro-ph/9509016
Study of the dynamics of the core of A2218
We report the results of an attempt to study the velocity structure of the core of the cluster A2218 in order to probe its dynamical state. The aim is to understand if the core is indeed virialized? relaxed? or in hydrodynamic equilibrium? We use cluster lensing data in conjunction with the optical galaxy data to solve...
1995-09-04
2007-05-23
[ "astro-ph" ]
Priyamvada Natarajan
astro-ph/9509010
Using Tidal Tails to Probe Dark Matter Halos
We use simulations of merging galaxies to explore the sensitivity of the morphology of tidal tails to variations of the halo mass distributions in the parent galaxies. Our goal is to constrain the mass of dark halos in well-known merging pairs. We concentrate on prograde encounters between equal mass galaxies which rep...
1995-09-04
2008-11-26
[ "astro-ph" ]
John Dubinski, J. Christopher Mihos, and Lars Hernquist
astro-ph/9509008
The Topology of The Cosmic Microwave Background Anisotropy on The Scale 1 degree
In this paper we develop the theory of clusterization of peaks in a Gaussian random field. We have obtained new mathematical results from this theory and the theory of percolation and have proposed a topological method of analysis of sky maps based on these results. We have simulated $10^o\times10^o$ sky maps of the co...
1995-09-02
2009-10-28
[ "astro-ph" ]
D.I. Novikov and H.E. Jorgensen
astro-ph/9509009
Theory of Pixel Lensing
Pixel lensing, gravitational microlensing of unresolved stars, is potentially much more sensitive and much more widely applicable than is generally recognized. I give explicit expressions for the pixel noise induced by a time-variable PSF, by photometric and geometric misalignment, and by discrete pixelization, and I s...
1995-09-02
2008-11-26
[ "astro-ph" ]
Andrew Gould
astro-ph/9509003
Models of Soft X-Ray Transients and Dwarf Novae
Models of Soft X--ray Transients are presented and compared with observations. The importance of inner advection--dominated flows in quiescent transient sources is discussed, as well as the problem of global stability of the standard outer accretion disc. A comparison is made with similar problems in dwarf nova models.
1995-09-01
2016-01-27
[ "astro-ph" ]
J.P. Lasota
astro-ph/9509004
Dwarf Novae at Low Mass Transfer Rates
We show that if the inner regions of accretion discs in quiescent dwarf nova systems are removed by magnetic disruption or evaporated by siphon flows, the remaining disc is globally stable for mass transfer rates $\lta 10^{15}$ g s$^{-1}$. This implies that (super)outbursts in these systems have to be triggered by an e...
1995-09-01
2011-05-23
[ "astro-ph" ]
J.P. Lasota, J.M. Hameury and J.M. Hure
astro-ph/9508159
Formation of Structure in the Universe
An introduction to modern theories for the origin of structure in the Universe is given. After a brief review of the growth of cosmological perturbations in an expanding Universe and a summary of some important observational results, the lectures focus on the inflationary Universe scenario and on topological defect mod...
1995-09-01
2008-02-03
[ "astro-ph", "hep-ph" ]
Robert H. Brandenberger (Brown University and Univ. of British Columbia)
astro-ph/9509001
Colour Gradients in the Optical and Near-IR
For many years broadband colours have been used to obtain insight into the contents of galaxies, in particular to estimate stellar and dust content. Broadband colours are easy to obtain for large samples of objects, making them ideal for statistical studies. In this paper I use the radial distribution of the colours in...
1995-09-01
2019-07-31
[ "astro-ph" ]
Roelof S. de Jong (University of Durham)
astro-ph/9508158
BATSE Gamma-Ray Burst Line Search: IV. Line Candidates from the Visual Search
We evaluate the significance of the line candidates identified by a visual search of burst spectra from BATSE's Spectroscopy Detectors. None of the candidates satisfy our detection criteria: an F-test probability less than 10^-4 for a feature in one detector and consistency among the detectors which viewed the burst. M...
1995-09-01
2009-10-28
[ "astro-ph" ]
D. L. Band, S. Ryder, L. A. Ford, J. L. Matteson (UCSD), D. M. Palmer, B. J. Teegarden (NASA/GSFC), M. S. Briggs, W. S. Paciesas, G. N. Pendleton, R. D. Preece (UAH)
astro-ph/9509005
Lagrangian Perturbation Approach to the Formation of Large-scale Structure
The present lecture notes address three columns on which the Lagrangian perturbation approach to cosmological dynamics is based: 1. the formulation of a Lagrangian theory of self--gravitating flows in which the dynamics is described in terms of a single field variable; 2. the procedure, how to obtain the dynamics of Eu...
1995-09-01
2007-05-23
[ "astro-ph", "gr-qc" ]
T. Buchert
astro-ph/9509007
Chemistry and Kinematics in the Solar Neighborhood: Implications for Stellar Populations and for Galaxy Evolution
The immediate Solar neighborhood should be a fair sample of the local Galaxy. However, the chemical abundance distribution of long-lived disk stars very near the Sun contains a factor of five to ten more metal-poor stars, $-1 \simlt {\rm [Fe/H]} \simlt -0.4$ dex, than is consistent with modern star-count models of larg...
1995-09-01
2011-05-05
[ "astro-ph" ]
Rosemary F.G. Wyse (JHU; IoA, Cambridge; CfPA, Berkeley) and Gerard Gilmore (IoA, Cambridge)
astro-ph/9509006
Coalescing Neutron Stars -- a Step Towards Physical Models. I. Hydrodynamic Evolution and Gravitational-Wave Emission
We investigate the dynamics and evolution of coalescing neutron stars. Although the code (Piecewise Parabolic Method) is purely Newtonian, we do include the emission of gravitational waves and their backreaction on the hydrodynamic flow. The properties of neutron star matter are described by the physical equation of st...
1995-09-01
2008-11-26
[ "astro-ph" ]
M. Ruffert, H.-Th. Janka, G. Schaefer
astro-ph/9509002
Mechanisms for Dwarf Nova Outbursts and Soft X-Ray Transients
I review models trying to explain dwarf-nova outbursts and soft X-ray transients. The disc-instability model for dwarf-novae is still in its preliminary state of development: its predictions depend very strongly on the unknown viscosity mechanism. It is also doubtful that a {\sl pure} disc-instability phenomenon will b...
1995-09-01
2011-04-15
[ "astro-ph" ]
J.P. Lasota
astro-ph/9508153
New Results on the Coma cluster: Revealing the Primary Component
Recent observations of the Coma cluster of galaxies in its central region have provided approximately 250 new redshifts - allowing a good membership criterion to be established for brighter galaxies - and magnitudes for 8000 objects in the same region derived from photometric data complete up to V$_{26.5}$=22.5. A thor...
1995-08-31
2007-05-23
[ "astro-ph" ]
F. Durret, A. Biviano, D. Gerbal, O. Le Fevre, C. Lobo, A. Mazure, E. Slezak
astro-ph/9508149
The Kinematics of Emission-Line Galaxies in Clusters from ENACS
By using the ENACS data, we have studied the properties of emission-line galaxies (ELG) in clusters. The fraction of ELG in clusters is 16~%; this fraction is slightly dependent on the cluster velocity dispersion, being larger for ``colder'' systems. ELG tend to occur more frequently than other cluster galaxies in subs...
1995-08-31
2007-05-23
[ "astro-ph" ]
A. Biviano, P. Katgert, A. Mazure, M. Moles, R. den Hartog, P. Focardi
astro-ph/9508152
Small Groups of Galaxies: a Clue to a Critical Universe
We study the formation and the evolution of galaxy groups in a critical universe, showing the importance of secondary infall for their dynamical evolution. Merging is only slightly accelerated if galaxies have massive halos, because the mass initially associated to the individual galaxies is soon tidally stripped. Stri...
1995-08-31
2009-10-28
[ "astro-ph" ]
Fabio Governato, Paolo Tozzi and Alfonso Cavaliere (Univ. Tor Vergata)
astro-ph/9508157
Why Not Consider Closed Universes?
We consider structure formation and CMB anisotropies in a closed universe, both with and without a cosmological constant. The CMB angular power spectrum and the matter transfer function are presented, along with a discussion of their relative normalization. This represents the first full numerical evolution of density ...
1995-08-31
2009-08-18
[ "astro-ph" ]
Martin White & Douglas Scott
astro-ph/9508150
A non-parametric and scale-independent method for cluster analysis II: the multivariate case
A general method is described for detecting and analysing galaxy systems. The multivariate geometrical structure of the sample is studied by using an extension of the method which we introduced in a previous paper. The method is based on an estimate of the probability density underlying a data sample. The density is es...
1995-08-31
2015-06-24
[ "astro-ph" ]
Armando Pisani
astro-ph/9508154
Minkowski Functionals in Cosmology
Minkowski functionals provide a novel tool to characterize the large-scale galaxy distribution in the Universe. Here we give a brief tutorial on the basic features of these morphological measures and indicate their practical application for simulation data and galaxy redshift catalogues as examples.
1995-08-31
2008-02-03
[ "astro-ph" ]
J. Schmalzing, M. Kerscher, T. Buchert
astro-ph/9508148
The Cosmological Density and Ionization of Hot Gas: Oxygen VI Absorption in Quasar Spectra
We have conducted the first survey for Oxygen VI $\lambda\lambda 1032,1038$ absorption lines in QSO spectra. We used medium resolution ($R \approx 1300$) high signal-to-noise ($\approx 20$) Faint Object Spectrograph spectra of 11 QSOs ($0.53\leq$\zem$\leq2.08$) from the Hubble Space Telescope Archive. We use simulated ...
1995-08-31
2009-10-28
[ "astro-ph" ]
Scott Burles & David Tytler (CASS, University of California at San Diego)
astro-ph/9508151
Stellar Orbits in Barred Galaxies with Nuclear Rings
We investigate the dynamical response of stellar orbits in a rotating barred galaxy potential to the perturbation by a nuclear gaseous ring. The change in 3D periodic orbit families is examined as the gas accumulates near the inner Lindblad resonance. It is found that the x2/x3 loop extends to higher Jacobi energy and ...
1995-08-31
2007-05-23
[ "astro-ph" ]
C.H. Heller and I. Shlosman
astro-ph/9508155
Gamma Ray Pulsars: Emission from Extended Polar Cap Cascades
We have used a Monte Carlo simulation of a Polar Cap (PC) model of gamma-ray pulsars to estimate light curves and phase-resolved spectra for sources whose rotational and magnetic axes are oriented so that only one of the magnetic poles produces emission directed at the Earth. In this Single Polar Cap (SPC) scenario, ev...
1995-08-31
2009-10-28
[ "astro-ph" ]
Joseph K. Daugherty (UNCA) & Alice K. Harding (NASA/GSFC)
astro-ph/9508156
Faint Blue Galaxies and the Epoch of Dwarf-Galaxy Formation
Both theoretical and observational lines of reasoning suggest that the very faint (B > 24) galaxies seen in deep images of the sky are small low-mass galaxies that experienced starburst at 0.5<z<1 and have since faded into low luminosity, low surface brightness objects. We scrutinize this hypothesis in order to determi...
1995-08-31
2009-06-19
[ "astro-ph" ]
Arif Babul and Henry C. Ferguson
astro-ph/9508146
A Self-Consistent Dynamical Model for the {\sl COBE} Observed Galactic Bar and Its Application to Microlensing
A self-consistent stellar dynamical model for the Galactic bar is constructed from about 500 numerically computed orbits with an extension of the Schwarzschild technique. The model fits the {\sl COBE} found asymmetric boxy light distribution and the observed stellar kinematics of the bulge. The model potential is also ...
1995-08-30
2007-05-23
[ "astro-ph" ]
HongSheng Zhao
astro-ph/9508147
Shell Masers
We present the analytical solution of a maser shaped like a spherical shell. We determine the general condition on the size of the central cavity at which a sphere becomes a shell maser, and derive the intensity, beaming angle and observed size of both unsaturated and saturated shells.
1995-08-30
2011-05-23
[ "astro-ph" ]
Moshe Elitzur (University of Kentucky), V. Bujarrabal (Yebes Observatory, Spain)
astro-ph/9508145
A Sharp Event in the Image a Light Curve of the Double Quasar 0957+561 and Prediction of the 1996 Image B Light Curve
CCD photometry of the gravitational lens system 0957+561A,B in the g and r bands was obtained on alternate nights, weather permitting, from December 1994 through May 1995 using the Double Imaging Spectrograph (DIS) on the Apache Point Observatory (APO) 3.5-meter telescope. The remote observing and fast instrument chang...
1995-08-30
2012-08-27
[ "astro-ph" ]
T. Kundic, W.N. Colley, J.R. Gott, III, S. Malhotra, U. Pen, J.E. Rhoads, K.Z. Stanek, E.L. Turner, J.Wambsganss
astro-ph/9508144
Implications of New JHK Photometry and a Deep Infrared Luminosity Function for the Galactic Bulge
We present deep near-IR photometry for Galactic bulge stars in Baade's Window, $(l,b) = (1.0\deg, -3.9\deg),$ and another minor axis field at $(l,b) = (0^\circ,-6^\circ)$. We combine our data with previously published photometry and construct a luminosity function over the range $5.5 \leq K_0 \leq 16.5$, deeper than an...
1995-08-30
2016-08-30
[ "astro-ph" ]
Glenn P. Tiede, Jay A. Frogel, and D. M. Terndrup (Ohio State University)
astro-ph/9508143
Peak statistics on COBE maps
We perform the stastistics of temperature maxima and minima in COBE-DMR 2-year maps. For power-law spectra the surface distribution of peaks implies an amplitude consistent with more conventional analyses of COBE data (for instance, we get $Q_{{\rm rms-PS}}=17\pm 3\ \mu $K for a spectral index $% n=1),$ but not with th...
1995-08-30
2011-05-10
[ "astro-ph" ]
R. Fabbri and S. Torres
astro-ph/9508138
A physical distance indicator for spiral galaxies
In this paper we derive a Tully Fisher relation from measured I band photometry and H$\alpha$ rotation curves of a large survey of southern sky spiral galaxies, obtained in Persic \& Salucci (1995) by deprojecting and folding the raw H$\alpha$ data of Mathewson, Ford \& Buchhorn (1992). We calibrate the relation by com...
1995-08-29
2007-05-23
[ "astro-ph" ]
M. A. Hendry, S. Rauzy, P. Salucci, M. Persic
astro-ph/9508139
Distance Estimation in Cosmology
In this paper we outline the framework of mathematical statistics with which one may study the properties of galaxy distance estimators. We describe, within this framework, how one may formulate the problem of distance estimation as a Bayesian inference problem, and highlight the crucial question of how one incorporate...
1995-08-29
2009-10-28
[ "astro-ph" ]
M.A. Hendry, J.F.L. Simmons
astro-ph/9508142
Self-similarity and scaling behavior of scale-free gravitational clustering
We measure the scaling properties of the probability distribution of the smoothed density field in $N$-body simulations of expanding universes with scale-free initial power-spectra, with particular attention to the predictions of the stable clustering hypothesis. We concentrate our analysis on the ratios $S_Q(\ell)\equ...
1995-08-29
2009-10-28
[ "astro-ph" ]
S. Colombi, F.R. Bouchet and L. Hernquist
astro-ph/9508136
Thresholds on star formation and the chemical evolution of galactic discs: cosmochronology and the age of the galaxy
In this paper we analyse different chronometers based on the models of chemical evolution developed in Chamcham, Pitts \& Tayler (1993; hereafter CPT) and Chamcham \& Tayler (1994; hereafter CT). In those papers we discussed the ability of our models to reproduce the observed G-dwarf distribution in the solar neighbour...
1995-08-29
2015-06-24
[ "astro-ph" ]
K. Chamcham and M. A. Hendry
astro-ph/9508137
Combined stellar structure and atmosphere models for massive stars II. Spectral evolution on the main sequence
In Schaerer et al. (1995, Paper I) we have presented the first "combined stellar structure and atmosphere models" (CoStar) for massive stars, which consistently treat the entire mass loosing star from the center out to the outer region of the stellar wind. The models use up-to-date input physics and state-of-the-art te...
1995-08-29
2007-05-23
[ "astro-ph" ]
D. Schaerer, A. de Koter, W. Schmutz, A. Maeder
astro-ph/9508133
A Multi-Species Model for Hydrogen and Helium Absorbers in Lyman-Alpha Forest Clouds
We have performed a multi-species hydrodynamical simulation of the formation and evolution of Lyman alpha clouds in a flat CDM dominated universe with an external flux of ionizing radiation. We solve the fully coupled non-equilibrium rate equations for the following species: H, H^+, H^-, H_2, H_2^+, He, He^+, He^{++}, ...
1995-08-29
2009-10-28
[ "astro-ph" ]
Yu Zhang, Peter Anninos and Michael L. Norman (NCSA)
astro-ph/9508135
Stellar Dynamics and the 3D Structure of Bars
Recent observational constraints restrict the strict applicability of stellar dynamics in spirals to a few rotation periods. However, stellar dynamics concepts such as periodic orbits are invaluable for understanding the various dynamical processes occurring during much more periods. A distinction of two instability ty...
1995-08-29
2008-02-03
[ "astro-ph" ]
D. Pfenniger
astro-ph/9508140
High Resolution BIMA Observations of CO, HCN, and 13CO in NGC 1068
We present high-resolution CO, HCN, and 13CO maps of the inner arcminute of NGC 1068 made with the BIMA interferometer. Several features appear in the CO map which have not previously been observed: (1) a firm detection of CO line emission from a compact region centered on the nucleus of the galaxy; (2) the detection o...
1995-08-29
2007-05-23
[ "astro-ph" ]
Tamara T. Helfer and Leo Blitz (University of Maryland)
astro-ph/9508134
Combined stellar structure and atmosphere models for massive stars I. Interior evolution and wind properties on the main sequence
We present the first "combined stellar structure and atmosphere models" (CoStar) for massive stars, which consistently treat the entire mass loosing star from the center out to the asymptotic wind velocity. The models use up-to-date input physics and state-of-the-art techniques to model both the stellar interior and th...
1995-08-29
2007-05-23
[ "astro-ph" ]
D. Schaerer, A. de Koter, W. Schmutz, A. Maeder
astro-ph/9508141
Intracluster Globular Clusters
Globular cluster populations of supergiant elliptical galaxies are known to vary widely, from extremely populous systems like that of UGC 9799, the centrally dominant galaxy in Abell 2052, to globular-cluster-poor galaxies such as NGC 5629 in Abell 2666. Here we propose that these variations point strongly to the exist...
1995-08-29
2009-10-28
[ "astro-ph" ]
Michael J. West, Patrick Cote, Christine Jones, William Forman and Ronald O. Marzke
astro-ph/9508130
New Observations and a New Interpretation of CO(3--2) in IRAS F10214+4724
New observations with the IRAM interferometer of CO(3--2) from the highly luminous galaxy IRAS F10214+4724 show the source is 1.5'' x <= 0.9'' ; they display no evidence of any velocity gradient. This size, together with optical and IR data that show the galaxy is probably gravitationally lensed, lead to a new model fo...
1995-08-28
2009-10-28
[ "astro-ph" ]
D. Downes, P.M. Solomon and S.R. Radford
astro-ph/9508128
Evolution of a Magnetic Flux Tube in a Sunspot Penumbra
The motion of an individual magnetic flux tube inside the penumbra of a sunspot is studied numerically. Here, we present preliminary results. The thin flux tube approximation together with a simplified radiative heat exchange with the surroundings is used to study the evolution of a flux tube embedded into a background...
1995-08-28
2007-05-23
[ "astro-ph" ]
K. Jahn, R. Schlichenmaier, H.U. Schmidt
astro-ph/9508127
The Near-Infrared Fundamental Plane of Elliptical Galaxies
We present results from a near-infrared $K$-band imaging survey of 59 elliptical galaxies in five nearby clusters. We measure photometric parameters for each galaxy using surface photometry and draw velocity dispersions from the literature. Three observables define a near-infrared Fundamental Plane (FP) of elliptical g...
1995-08-28
2009-10-28
[ "astro-ph" ]
M. A. Pahre, S. G. Djorgovski, and R. R. de Carvalho (Palomar Observatory, Caltech)
astro-ph/9508129
Evolution of the Ly$\alpha$ forest: a consistent picture
We study the evolution with redshift of the number density of Ly$\alpha$ clouds in a CDM model using numerical simulations including photo-ionization and cooling of the baryonic component. The photo-ionizing flux is consistently taken as proportional to the rate at which material cools below 5000~K in the simulation. T...
1995-08-28
2019-08-17
[ "astro-ph" ]
Jan P. M\"ucket, Patrick Petitjean, Ronald E. Kates, R\"udiger Riediger
astro-ph/9508132
Observational Evidence for a Bar in the Milky Way
Evidence from a variety of sources points towards the existence of a bar in the central few kpc of the Galaxy. The measurements roughly agree on the direction of the bar major axis, but other parameters (axis ratio, size, pattern speed) are still poorly determined. Current dynamical models are limited by the quality of...
1995-08-28
2008-02-03
[ "astro-ph" ]
Konrad Kuijken
astro-ph/9508131
New "Einstein Cross" Gravitational Lens Candidates in HST WFPC2 Survey Images
We report the serendipitous discovery of ``Einstein cross'' gravitational lens candidates using the Hubble Space Telescope. We have so far discovered two good examples of such lenses, each in the form of four faint blue images located in a symmetric configuration around a red elliptical galaxy. The high resolution of H...
1995-08-28
2009-10-28
[ "astro-ph" ]
Kavan U. Ratnatunga, Eric J. Ostrander, Richard E. Griffiths, and Myungshin Im (HST Medium Deep Survey, Johns Hopkins University, Baltimore, MD)
astro-ph/9508125
A new method for accurate velocity statistics estimation
We introduce two new methods to obtain reliable velocity field statistics from N-body simulations, or indeed from any general density and velocity fluctuation field sampled by discrete points. These methods, the {\it Voronoi tessellation method} and {\it Delaunay tessellation method}, are based on the use of the Vorono...
1995-08-26
2017-03-08
[ "astro-ph" ]
Francis Bernardeau and Rien van de Weygaert
astro-ph/9508124
Modelling the Nonlinear Gravitational Clustering in the Expanding Universe
The gravitational clustering of collisionless particles in an expanding universe is modelled using some simple physical ideas. I show that it is indeed possible to understand the nonlinear clustering in terms of three well defined regimes: (1) linear regime (2) quasilinear regime which is dominated by scale-invariant r...
1995-08-26
2016-06-08
[ "astro-ph" ]
T.Padmanabhan
astro-ph/9508126
Wandering in the Background: A CMB Explorer
We develop and examine the principles governing the formation of distortions in the cosmic microwave background. Distortions in the frequency or spectral distribution of the background probe the thermal history of the universe whereas those in the angular temperature distribution probe its dynamics and geometry. Stress...
1995-08-26
2009-07-17
[ "astro-ph" ]
Wayne Hu (UC Berkeley, Ias)
astro-ph/9508123
Infimum Microlensing Amplification of the Maximum Number of Images of $n$-point Lens Systems
The total amplification of a source inside a caustic curve of a binary lens is no less than 3. Here we show that the infimum amplification 3 is satisfied by a family of binary lenses where the source position is at the mid-point between the lens positions independently of the mass ratio which parameterizes the family. ...
1995-08-26
2016-08-30
[ "astro-ph" ]
Sun Hong Rhie (IGPP/LLNL)
astro-ph/9508121
Structure formation: Models, Dynamics and Status
The constraints on the models for the structure formation arising from various cosmological observations at different length scales are reviewed. The status of different models for structure formation is examined critically in the light of these observations.
1995-08-25
2007-05-23
[ "astro-ph" ]
T.Padmanabhan
astro-ph/9508122
Distances to Nearby Galaxies: Combining Fragmentary Data Using Four Different Methods
The primary distance indicators are established in our Galaxy and the Local Group. There are at least four different methods which give good distances: methods using proper motions, RR Lyraes, Cepheid variables, and Type II supernovae. However the data on independent distances is very fragmentary, due partly to nature ...
1995-08-25
2009-10-28
[ "astro-ph" ]
Dragan Huterer (MIT), Dimitar D. Sasselov (CfA), and Paul L. Schechter (MIT)
astro-ph/9508117
Inverse Dynamical Population Synthesis and Star Formation
We investigate the hypothesis that stars form in aggregates of binary systems and that the dynamical evolution of these aggregates leads to the observed properties of binary stars in the Galactic field. We assume that the initial distribution of periods is flat in logP, where P is the orbital period in days, and 3<logP...
1995-08-25
2015-06-24
[ "astro-ph" ]
Pavel Kroupa
astro-ph/9508118
Fast Rotation of Neutron Stars
We show that for realistic equations of state of dense matter, the universal proportionality factor relating the maximum rotation rate of neutron stars due to mass-shedding limit to the mass and radius of maximum allowable mass configuration of non-rotating models results from a universal proportionality between masses...
1995-08-25
2009-10-28
[ "astro-ph" ]
J.-P. Lasota, P. Haensel, and M.A. Abramowicz
astro-ph/9508120
Non-Flat Power Spectra in the CDM Model
Standard inflation with one scalar field produces primordial perturbations with a nearly flat ('Harrison-Zeldovich') power spectrum. Here we consider first, a double inflation spectrum, and second, a massive scalar field with an interaction potential which mimics an early quartic interaction, but fading away at a chara...
1995-08-25
2016-08-30
[ "astro-ph" ]
Lutz V. Semig, Volker Mueller
astro-ph/9508116
On the deprojection of axisymmetric bodies
Axisymmetric density distributions are constructed which are invisible when viewed from a range of inclination angles $i$. By adding such distributions to a model galaxy, it can be made either disky or boxy without in any way affecting its projected image. As the inclination of a galaxy decreases from edge-on to face o...
1995-08-25
2015-06-24
[ "astro-ph" ]
Ortwin Gerhard (Astron.Inst, Univ.Basel, CH) and James Binney (Dpt.Theoret.Phys., Oxford, UK)
astro-ph/9508115
On the deprojection of the Galactic bulge
An algorithm is developed and tested for the problem posed by photometric observations of the bulge of the Milky Way. The latter subtends a non-trivial solid angle on the sky, and we show that this permits inversion of the projected brightness distribution under the assumption that the bulge has three orthogonal mirror...
1995-08-25
2015-06-24
[ "astro-ph" ]
James Binney (Dpt.Theoret.Phys., Oxford, UK) and Ortwin Gerhard (Astron.Inst, Univ.Basel, CH)
astro-ph/9508119
Bar Formation, Evolution and Destruction
I review the various mechanisms for creating bars in rotating stellar disks, and conclude that the swing-amplified feed-back loop, which produces rapidly tumbling bars, remains the most probable. The bar continues to evolve after its formation in a number of ways; here I discuss what appears to be inevitable thickening...
1995-08-25
2007-05-23
[ "astro-ph" ]
J A Sellwood (Rutgers University)
astro-ph/9508114
Local Approximations to the Gravitational Collapse of Cold Matter
We investigate three different local approximations for nonlinear gravitational instability in the framework of cosmological Lagrangian fluid dynamics of cold dust. They include the Zel'dovich approximation (ZA), the ``non-magnetic'' approximation of Bertschinger \& Jain (1994, NMA), and a new ``local tidal'' approxima...
1995-08-24
2011-07-19
[ "astro-ph", "gr-qc" ]
Lam Hui and Edmund Bertschinger
astro-ph/9508109
Simulation of microlensing lightcurves by combining contouring and rayshooting
The contouring methods described by Lewis et al. (1993) and Witt (1993) are very efficient and elegant for obtaining the magnification of a point source moving along a straight track in the source plane. The method is, however, not very efficient for extended sources, because the amplification needs to be computed for ...
1995-08-24
2007-05-23
[ "astro-ph" ]
S. V. H. Haugan (Institute of Theoretical Astrophysics, University of Oslo)
astro-ph/9508108
A Rigorous Proof of the Inflationary Spectrum
Fundamental formulae representing the density perturbation spectrums generated in inflationary scenarios are rigorously proved. Quantum fluctuations as initial conditions for structure generation in some inflationary era can be calculated in general scale. Thus, we could avoid the matching of the large and the small sc...
1995-08-24
2008-11-26
[ "astro-ph", "gr-qc" ]
J. Hwang
astro-ph/9508113
Low threshold particle arrays
While atmospheric Cherenkov telescopes have a small field of view and a small duty fraction, arrays of particle detectors on ground have a 1\,sr field of view and a 100% duty fraction. On the other hand, particle detector arrays have a much higher energy threshold and an inferior hadron rejection as compared to Cherenk...
1995-08-24
2009-10-28
[ "astro-ph" ]
K. Bernl\"ohr (Max-Planck-Institut f\"ur Kernphysik, Heidelberg)
astro-ph/9508107
The MACHO Data Pipeline
The MACHO experiment is searching for dark matter in the halo of the Galaxy by monitoring more than 20 million stars in the LMC and Galactic bulge for gravitational microlensing events. The hardware consists of a 50 inch telescope, a two-color 32 megapixel ccd camera, and a network of computers. On clear nights the sys...
1995-08-24
2007-05-23
[ "astro-ph" ]
T. S. Axelrod (MSSSO and LLNL), R. A. Allsman (ANUSF), P. J. Quinn (ESO), D. P. Bennett (CfPA), K. C. Freeman, B.A. Peterson, A. W. Rodgers (MSSSO), C. Alcock, K. H. Cook (LLNL), K. Griest (UCSD), S. L. Marshall, M. R. Pratt, C. W. Stubbs (UW), and W. Sutherland (Oxford)
astro-ph/9508112
Separating intrinsic and microlensing variability using parallax measurements
In gravitational lens systems with 3 or more resolved images of a quasar, the intrinsic variability may be unambiguously separated from the microlensing variability through parallax measurements from 3 observers when there is no relative motion of the lens masses (Refsdal 1993). In systems with fewer than 3 resolved im...
1995-08-24
2007-05-23
[ "astro-ph" ]
S. V. H. Haugan (Institute of Theoretical Astrophysics, University of Oslo)