bluuebunny/crossref_metadata_2025 huggingface dataset:
The Response of the Ensemble of Molecular Clouds to Bar Forcing in a Galaxy Disk
Authors: Combes F. , Gerin M.
Published: June 2019

How a bar potential can force a spiral structure in the gas component is now well understood. This response is due to the dissipative character of the gas. Results of the computations of the response differ greatly with the numerical code adopted, either particle (Schwarz 1981), or hydrodynamic (e.g. Sanders and Huntley, 1976) and within a given code, with the spatial resolution used, since the artificial viscosity is thus varied (see e.g. van Albada et al 1981). According to observations, the gas component is mostly cloudy. Hence our aim is to compute the response to a bar potential of the ensemble of molecular clouds for which collision rate (and therefore dissipation rate) is relatively well-known. Using a particle code and explicitly treating the collisions between clouds, the viscosity parameter is more easily controlled and less artificial. Also, since the mass transfer between clouds is taken into account, we will obtain insight into the formation of large molecular clouds, which are the preferential sites of active star formation.
Scale-Free Models of Elliptical Galaxies
Authors: Richstone Douglas O.
Published: June 2019

In this note I will report the general character of all scale-free solutions of the collisionless Boltzmann and Poisson equations for a specific shape. In this case, the density falls as r−2 along any radial ray, the potential is logarithmic with oblate spheroidal level surfaces, and the flattening corresponds to an E5 or E6 density distribution (see Richstone 1980, hereafter Paper I). Schwarzschild's (1979) method was used. Toomre (1982) has recently discussed the properties of scale free models of this sort with distribution functions dependent on only the two classical isolating integrals. The method used here automatically incorporates the third integral.
Neutral Hydrogen Observations of the Dwarf Elliptical Galaxies NGC 185 and NGC 205
Authors: Gottesman S. T. , Johnson D. W.
Published: June 2019

In this note we report the detection and mapping of neutral hydrogen in two dwarf elliptical galaxies NGC 185 and NGC 205. Both are companions to M 31 and both are classified as peculiar owing to the presence of obscurring dust patches near their nuclei. Both galaxies also contain a small population of blue, presumably young stars (Hodge 1963, 1973).
Extended Gaseous Emission in Normal Elliptical Galaxies
Authors: Ulrich M. H.
Published: June 2019

It has been known for several decades that about 15% of elliptical galaries contain ionized gas yet very little data is available in the literature on the properties of this gas such as spatial distribution, velocity field, and abundances. The properties of this gas are related to current problems about elliptical galaxies: (1) origin of the gas (stellar mass loss vs. accretion from a nearby gas-rich galaxy or an intergalactic cloud); (2) structure of the galaxy itself, because the locus of the stationary orbits of the gas depends on whether the galaxy is prolate or oblate and on whether the galaxy is rotating or not; (3) the relationship between the presence of gas in elliptical galaxies and their radio properties.
Dust and Gas in Triaxial Galaxies
Authors: Lake George , Norman Colin
Published: June 2019

There are many reasons to consider the dynamics of triaxial galaxies. Elliptical galaxies are not rotationally flattened (Illingworth, this conference) and their isophotal profiles are often twisted. N-body simulations of collapse have produced a number of final state figures which are triaxial. Even those still skeptical will have to grant that barred spirals (a category which seems to include the Galaxy) are certainly not axisymmetric.
Environmental Effects on Galaxies in Clusters
Authors: Miller R. H. , Smith B. F.
Published: June 2019

This study is part of a program to investigate consequences to a galaxy of its orbiting within a cluster of galaxies. Numerical experiments have been conducted to study the tidal influences on the internal dynamics of a galaxy (Miller and Smith 1982). The present first cut at the general problem treats effects of the cluster's tidal potential on the pattern motion and observable properties of a galaxy (shape, density contours, velocity fields, velocity dispersions) for a fixed external potential. The first-order cluster force field is balanced by the galaxy's acceleration in the real cluster, leaving tidal terms as the leading terms in a Taylor series expansion of the cluster force field about the center of the galaxy. The cluster tidal force field is usually stretching along a line toward the cluster center and compressive at right angles.
Energy Transfer during the Tidal Encounter of Disc Galaxies
Authors: Palmer Philip L.
Published: June 2019

Numerical simulations of merging galaxies do not include a disc component due to bar instability modes. Analytic work is based upon the impulsive approximation which leads to energy loss by the perturber. However, for the perturber to become bound we need consider parabolic encounters. Here we present an analytic technique suitable for all types of encounters.
Systematics of Bulge-to-Disk Ratios
Authors: Simien F. , de Vaucouleurs G.
Published: June 2019

The main results of a new analysis of the spheroidal (I) and disk (II) components of 98 lenticular and spiral galaxies are :

(i)

on the average, the magnitude difference between spheroid and total luminosity, ΔmI = BT(I) - BT, varies smoothly along the Hubble sequence from early lenticulars to late-type spirals (Fig. 1);

(ii)

the trend of ΔmI confirms the concept of the lenticular class as intermediate between E and S classes, not as a parallel sequence;

(iii)

the large scatter at any given type, σ(ΔmI) ≃ 0.7 mag, is still dominated by measuring and decomposition errors.

(iv)

The effective surface brightness of the spheroid, μce(I), corrected for galactic extinction AB, decreases by ~2 mag from early to late types, but with a large range (~ 3 mag) at T = const. (Fig. 2a).

(v)

The effective surface brightness of the disks, corrected for galactic extinction and inclination, μce(II) = μe(II)- AB + 3 log R2s, is almost independent of type, with <μce(II)> ≃ 23.5 for spirals. This implies a corrected central surface brightness μc(0) = μce −1.82 ≃ 21.7, in good agreement with the Freeman rule, but with a large scatter. However, the disks of lenticulars (T< 0) tend to be ~ 0.5 mag fainter than the disks of spirals (Fig. 2b).

(vi)

The linear effective radii of the spheroidal components are largest,  ≳ 1 kpc, among the early type spirals, in agreement with the Hubble classification criterion. The spheroid of lenticulars and late-type spirals tend to be smaller,  ≃ 0.5 kpc, but with a large scatter (Fig. 3a). There is no indication of systematic difference between ordinary (SA) and barred (SB) spirals.

(vii)

The linear effective radii of the disk components are largest  ≳ 5 kpc, among intermediate type spirals. The disks of lenticular and late type spirals tend to be smaller (Fig. 3b).

(viii)

The mean absolute magnitudes of the disk and spheroidal components depend on type (Fig. 4). On the average the disks are brighter (MII ≃ −19.5) among types Sb-Sbc, spheroids (MI ⋍ −19) among types L+ to Sa, but, again, with a large scatter. Disks and spheroids are about equally bright (MI ⋍ MII ⋍ − 19) at stage SO/a (T = 0).
The Formation of Galaxies
Authors: Gunn James E.
Published: June 2019

The presently fashionable ideas for galaxy formation are reviewed briefly, and it is concluded that the standard isothermal heirarchy fits the available data best. A simple infall picture is presented which explains many of the observed properties of disk galaxies.
The Mass and Structure of the Remnant of Tycho's Supernova
Authors: Gorenstein Paul , Seward Frederick , Tucker Wallace
Published: June 2019

A high resolution X-ray image of Tycho's supernova remnant obtained from the Einstein Observatory reveals three components of X-ray emission that we identify with shocked interstellar material, diffuse ejecta, and clumpy ejecta. This picture is applied to derive the mass of X-ray emitting material. Assuming a distance of 3 kpc, an absorbing column density of 3 × 1021 atoms/cm2, and using an ion-electron non-equilibrium calculation for the emissivity, we find the average density of the ISM is 0.4 atoms/cm3, and the energy contained in the remnant is 1.4 × 1051 ergs. The total mass of X-ray emitting material in the remnant is ≈4 M⊙, ≈2 M⊙ ejecta and ≈2 M⊙ swept up, putting the remnant at an intermediate state between a free expansion and the Sedov phase. There is no evidence for neutron star. The upper limit on the surface temperature is in the range 1.1 to 1.8 × 106K.
X-ray Study of the Crab Nebula and the Crab and Vela Pulsars
Authors: Harnden F. R.
Published: June 2019

The Crab Nebula has been intensely studied by X-ray astronomers ever since its discovery as the first, optically identified X-ray object (Bowyer et al. 1964); and a large majority of X-ray experiments during the past two decades have observed the Crab, seeking not only the answers to scientific questions but also assurance that the instruments' calibrations were understood. It is therefore no surprise that, following its launch in 1978 November, the Einstein X-ray Observatory too had the Crab Nebula on its list of mandatory targets.
The Crab Nebula's Jet
Authors: Fesen Robert , Gull Theodore
Published: June 2019

Using deeply exposed Schmidt plates, van den Bergh (1970) discovered a peculiar jetlike feature extending about 100″ beyond the Crab Nebula's northern boundary. The feature roughly coincided with a spur in the outer intensity contour map of the Crab's continuum emission (5200–6400A) made by Woltjer (1957) from plates taken by Baade with the 200 inch. However, little if any continuous synchroton emission is visible in the jet's region on Scargle's (1970) deep continuum photograph. More recent imaging of the jet by Chevalier and Gull (1975) and Wyckoff et al. (1976) using narrow passband interference-filters, show it slightly better than van den Bergh's plates, and indicate it is most visible in [0 III] 5007A emission. Spectroscopy of the jet's southern portion by Davidson (1978, 1979) confirmed that the [0 III] 4959A, 5007A lines are the brightest optical emissions in the jet and suggested a low radial velocity of about 100 km s−1
High Oxygen Abundance in a Bright Filament of the Crab Nebula
Authors: Péquignot Daniel
Published: June 2019

Detailed stationary photoionization models with homogeneous chemical composition were constructed for a bright filament of the Crab Nebula centered ~42″ W-SW of the pulsar. So far this filament is the only one which has been observed in the ultraviolet (Davidson et al, 1982), in the visual (Miller, 1978; Davidson et al, 1982) and in the near-infrared (Dennefeld and Péquignot, 1982), so that numerous constraints and meaningful tests of the models exist. On the other hand the computer program used in the calculations includes recently introduced atomic physics processes (charge exchange reactions and “low-temperature” di-electronic recombinations) and was tested and calibrated by means of models of the high-excitation planetary nebula NGC 7027 whose line spectrum shares some characteristics with that of the Crab Nebula.
The Peculiar X-ray Morphology of the SNR G292.0+1.8 : Evidence for an Asymmetric Supernova Explosion
Authors: Clark D. H. , Tuohy I. R.
Published: June 2019

A high resolution X-ray image from the Einstein Observatory of the young supernova remnant G292.0+1.8 (MSH11–54), previously noted as peculiar in terms of its spectral and morphological properties at optical and radio wavelengths, also shows an unusual X-ray morphology. Instead of a limb-brightened X-ray shell characteristic of most SNRs, the remnant consists of a central bar-like feature superposed on an ellipsoidal disc of approximately uniform surface brightness. We attribute the bar emission to a ring of oxygen-rich material ejected in the equatorial plane of a massive rotating progenitor, and the uniform disc component to emission from material with roughly cosmic composition heated by the accompanying blast wave. This interpretation provides observational support for the rotating precursor model of a Type II supernova discussed by Bodenheimer and Woosley.
The Kinematics of The SNR G292.0+1.8
Authors: Braun R. , Goss W. M. , Danziger I. J. , Boksenberg A.
Published: June 2019

Optical velocity field mapping of G292.0+1.8 in the [0III] λ5007 å line has been carried out using the IPCS with the 3.6 m ESO telescope at La Silla. Our data are not consistent with the suggestion that the [0III] emitting material in the western portion of this remnant is concentrated in an expanding ring. The existing data on G292.0+1.8 suggests that only the brightest portion of a thick shell of ejecta with high velocity spurs is observed. The expansion centroid, size, velocity and age of this SNR are derived.
The Structure and Emission of a Non-Radiative Shock
Authors: Raymond J. C.
Published: June 2019

Faint filaments are observed a few arcmin outside the bright optical filaments of the Cygnus Loop. They show nearly pure Balmer line emission spectra, and they are interpreted as emission from non-radiative shocks (1). Each neutral H atom passing through the shock front emits on average about 0.1 Hα photon before it is ionized. Since this radiation arises very close to the shock front, rather than in an extended post-shock cooling zone (2), it can be used to study the physics of the shock front itself. The structure of a shock poses several important questions (3). There may be an electron thermal conduction precursor ahead of the shock and there may be plasma turbulence. The shock thermalizes 3/4 of the bulk velocity of the incoming particles, so the ions initially have nearly all of the thermal energy. The electron and ion temperatures can reach equilibrium on the Coulomb collision time scale, but plasma turbulence may bring them into equilibrium much more rapidly. The Coulomb equilibration time scale is similar to the hydrogen ionization time, so that the hydrogen line emission will depend on the nature of the equilibration. The interpretation of the Hα line profile in terms of the shock velocity also depends on this equilibration, so this question is important for comparison of shock models with X-ray spectra.
X-ray Observations of Crab-Like Supernova Remnants
Authors: Becker R. H.
Published: June 2019

On the basis of extensive radio surveys of the galactic plane, approximately 140 sources of diffuse radio emission have been classified as supernova remnants (SNR). Using spectral index and spatial distribution as the primary selection criteria, these have been subdivided into two groups, “shell” and “Crab-like”. In each case, the radio emission is assumed to be of non-thermal origin. The two distinct morphologies arise from two distinct energy sources. For shell remnants, the energy is drawn from the reservoir of kinetic energy in the expanding shock front; in Crab-like remnants, the energy is drawn from the rotational kinetic energy of a central stellar remnant.

These two classes of remnants differ significantly in their x-ray emission. With few exceptions, radio shell remnants emit thermal x-rays from shock heated gas which is itself distributed in a shell. Crab-like sources (as defined by their radio properties) emit synchrotron x-rays in a centrally-peaked spatial distribution. Presumably, the x-ray emission from these objects is an extension of the radio spectrum. Crab-like sources have a high probability of containing a compact (unresolved) source of x-ray emission which in analogy to the Crab Nebula, is identified as the central stellar remnant.

The general absence of either compact x-ray sources or Crab-like diffuse nebulae within shell sources indicates that active pulsars are not usually formed in SN events which eventually form shell sources. However, there are several examples of remnants which share both shell and Crab-like characteristics so we cannot rule out an evolutionary connection between these two classes of SNR.
Radio Synthesis Maps of Large Supernova Remnants
Authors: Braun R. , van der Laan H. , Strom R. G.
Published: June 2019

Several large (at least 0.°5 diameter) supernova remnants (SNR) located at 2. °5 or more from the galactic plane have been mapped with the Westerbork Synthesis Radio Telescope (WSRT) at 49 cm. The sample, which includes IC443, DA530, VR042.05.01, CTA1 and OA184, is particularly suitable for complementary studies in other spectral regimes. By choosing objects at relatively high galactic latitudes we have consciously selected SNR which are likely to suffer less than average extinction and are probably nearer to the sun than most. This makes them particularly attractive for optical and X-ray studies which, along with IR and further radio observations, are either in progress or being planned. These are summarized in Table 1.
THeoretical Thermal X-Ray Maps of Supernova Remnants in Non-Uniform Media
Authors: Yorke H. W. , Tenorio-Tagle G. , Bodenheimer P.
Published: June 2019

The evolution of a supernova remnant resulting from an explosion near the edge of a molecular cloud is calculated with a 2-D hydrodynamical code (axial symmetry assumed). Cooling effects have been included. 1 kev X-ray maps of the remnant at different evolutionary times and different viewing angles are presented.
The Evolution of Supernova Remnants in a Non-Uniform Medium: The Fate of an Evolving OB Association
Authors: Bodenheimer P. , Yorke H. W. , Tenorio-Tagle G. , Beltrametti M.
Published: June 2019

We study the effect of multiple supernova explosions in a non-uniform interstellar medium using a two dimensional hydrodynamical code (axial symmetry assumed). Cooling effects were included. In a uniform medium two or more supernovae exploding at the same place but at different times result in a remnant with less energy than the sum of the individual explosion energies - when cooling effects are important. As a case of special interest the evolution of an OB association with many massive stars experiencing supernova explosions is presented. We show that it is difficult to produce large supershells with multiple supernovae alone, even if the sum of their explosion energies appear to be sufficient. The existence of a giant HII region preceding the explosions does not alter this conclusion. Other mechanisms should be considered to produce supershells.
Precessing Jet Model for the Supernova Remnant G109.1–1.0
Authors: Gregory P. C. , Fahlman G. G.
Published: June 2019

We propose that the central X-ray pulsar in G109.1–1.0, designated 1E 2259+586, ejects two oppositely directed precessing jets or beams, which give rise to the observed radio structure. The radio emission is interpreted as synchrotron emission from electrons accelerated at the interface of the jets with the walls of the SNR. Thus the observed intersecting arcs of radio emission represent the trace of the precessing jets on the supernova remnant walls. The precession axis is inclined at 37 degrees to the line of sight and the precession cone half angle is 55 degrees. The observed large scale X-ray jet in G109.1–1.0 is found to coincide in position with the precession axis as was found for the X-ray jets from SS 433.
Comparison of Radio and X-ray Observations of SNR G109.1–1.0
Authors: Gregory P. C. , Braun R. , Fahlman G. G. , Gull S. F.
Published: June 2019

In this paper, we present a comparison of the radio and X-ray morphology of the supernova remnant G109.1–1.0, based on recent radio observations at 6 and 20 cm and investigate the relationship of the SNR to a neighbouring molecular cloud.
Radio Observations of the Supernova Remnant CTB109 (G109.2–1.0)
Authors: Hughes V. A. , Harten R. H. , Costain C. , Nelson L. , Viner M. R.
Published: June 2019

The supernova remnant G109.2–1.0 was discovered at λ49cm by Hughes, Harten and van den Bergh (1981) during a survey of part of the Galactic plane. The northern part of it had been detected previously as the non-thermal radio source CTB109 by Wilson and Bolton (1960), and by Raghava Roa et al (1965), but the extended low brightness of the source and its close proximity to the very strong source Cas A, from which it is separated by ∼5′, excluded it from any further detailed study. It was discovered independently at X-ray wavelengths by Gregory and Fahlman (1980). Recently, the original WSRT radio observations have been found to be in error as a result of applying the CLEAN procedure to an extended source, and since the object appears to contain an X-ray pulsar (Fahlman and Gregory, 1981), it was decided to carry out a more detailed and extensive mapping of the remmant using different antenna arrays and frequencies. This paper describes the results obtained at λ49cm and λ21cm using the Westerbork Synthesis Radio Telescope (WSRT), at λ21cm using the aperture synthesis array at the Dominion Radio Astrophysical Observatory (DRAO) and at λ4.6cm using the 46m telescope of the Algonquin Radio Observatory (ARO). Thus, data has been obtained from three completely independent telescopes, using completely independent data reduction systems. Of importance is the fact that not only have wavelengths been chosen such that the larger dimensions of the array give a reasonable angular resolution of ≤1′, but also that the smallest spacing enables the larger angular dimensions of the remnant to be observed. This paper presents some of the results and a brief interpretation.
A Search for Pulsars Associated with Supernova Remnants in the Galaxy and the Magellanic Clouds
Authors: Manchester R. N. , Tuohy I. R. , D'Amico N.
Published: June 2019

It is widely accepted and almost certainly true that both pulsars and supernova remnants (SNRs) are products of the collapse of a star at the end of its evolution. Given this, it is a considerable puzzle why, of the more than 120 known SNRs in the Galaxy, only two have unambiguously associated pulsars. Beaming of the pulsar emission probably accounts for the absence of detectable pulsars in up to 80% of the SNRs; however, this still leaves 20–30 SNRs in which one should be able to detect a pulsar. Vivekanand and Narayan (1981) show that there is a deficit of pulsars with periods ≲0.5 s and suggest that a majority of pulsars do not become active for a time ∼104 years after their birth. This would account for the lack of pulsar-SNR associations. It is however possible that the observed lack of short-period pulsars is simply due to observational selection. In the past, most pulsar searches have been made at relatively low radio frequencies, typically close to 400 MHz. At these frequencies SNRs are bright and the effects of interstellar scattering are significant, especially for distant, short-period pulsars. Further, most of these searches have used a relatively long sampling interval, typically about 20 ms, which further reduces the sensitivity for short-period pulsars.
Three New Pulsars Near Supernova Remnants
Authors: Mohanty D. K.
Published: June 2019

A search for pulsars in the directions of twenty Galactic supernova remnants (SNRs) was carried out at 327 MHz with the Ooty Radio Telescope (ORT). We have measured the P for one of the pulsars which is just outside the shell of SNR W44 and discuss here the possibility of its association with the HI shell around W44. The parameters of the remaining two pulsars have not yet been determined with sufficient accuracy to suggest association with the respective SNRs.
Evolution of Neutron Stars in Young Supernova Remnants
Authors: Nomoto K. , Tsuruta S.
Published: June 2019

The exciting observational developments in recent years (see Seward, Helfand, Harnden, Becker, etc., in this volume) have made it worthwhile to reexamine neutron star cooling theories. Here we shall give an intermediate report on our work.
Optical Studies of Supernova Remnants in the Magellanic Clouds
Authors: Mathewson D. S. , Ford V. L. , Dopita M. A. , Tuohy I. R. , Long K. S. , Helfand D. J.
Published: June 2019

Optical identifications of 32 X-ray sources in the Magellanic Clouds confirm that they are SNRs. They are separated into four classes: the evolved, the oxygen-rich, the Balmer-dominated and the Crab-like. High velocity HI emission is observed from an extended region near 0525–66.0. It is suggested that this is produced by a possible Type III supernova which occurred out of the plane of the LMC and on the far side of the disk. The cumulative number-diameter relation for the LMC SNRs shows that they have evolved much faster than expected from the Sedov theory. It is suggested that this apparent “free-expansion” up to quite large diameters is due to the gradual conversion of the kinetic energy of the ejecta into thermal energy as they overtake the decelerating blast wave.
Optical Observations of SNRs and Ring Nebulae in the LMC
Authors: Rosado M. , Georgelin Y. M. , Laval A. , Monnet G.
Published: June 2019

The work we have performed on some of the SNRs and ring-shaped nebulae of the LMC refers mainly to: photographic plate Hα and [SII] (λλ 6717 Å) imagery and Fabry-Perot (FP) interferometry.
N49: The Site of a Gamma-ray Burst. Preliminary Results from X-ray Observations
Authors: Pizzichini G. , Cline T. L. , Desai U. D. , Teegarden B. J. , Evans W. D. , Fenimore E. E. , Klebesadel R. W. , Laros J. G. , Hurley K. , Niel M. , Vedrenne G.
Published: June 2019

The error box of the unusual Gamma-Ray Burst of March 5, 1979 falls completely inside the optical and radio image of the Supernova Remnant N49 in the Large Magellanic Cloud. This region was observed twice in x-rays with the High Resolution Imager of the Einstein Observatory, six weeks and nearly two years after the Gamma-Ray Burst. We show the comparison between the two observations.
QSO Surveys and Quasar Evolution
Authors: Braccesi A.
Published: June 2019

Recent results of QSO surveys are reviewed and QSO's cosmic evolution reconsidered.
The Asiago Catalogue of Quasi Stellar Objects
Authors: di Serego Alighieri S.
Published: June 2019

A catalogue containing the QSOs known with reasonable reliability from literature published before the end of 1981 has been compiled at the Asiago Observatory by C. Barbieri, M. Capaccioli, S. Cristiani, G. Nardon and A. Omizzolo, and will be published before the end of 1982 by the Memorie della Societá Astronomica Italiana.

The present release is an enlarged and updated version of that published by Barbieri et al. (1975). It provides basic data (names, equatorial and galactic coordinates at 1950.0, photometry, redshifts and information on radio emission, variability, morphology, presence of absorption lines, X-ray emission and finding charts) for 2004 QSOs, together with references, individual notes and cross reference tables. Two separate lists contain X-ray data for 271 QSOs (X-ray luminosity, optical-X and optical-radio spectral indexes) and absorption line data for 243 QSOs (absorption systems with their redshift, identified ions and wavelengths, spectral range, resolution and dispertion of the spectra).

The catalogue has been carefully checked for internal consistency and several discrepancies with the lists by Hewitt and Burbidge (1980) and by Véron and Véron (1975) have been resolved. The authors intend to provide a magnetic tape version of the catalogue to the Centre de Données Stellaires of the Strasbourg Observatory for distribution to the interested community.
Long-Term Variability of Quasi-Stellar Objects, and Their Distribution in the Hubble Diagram
Authors: Beckman John E. , Kidger Mark R.
Published: June 2019

A stochastic model for the energy source of QSO's is used to fit the light curves of 43 objects taken from long-period photometry (minimum duration of observations, 8 years per object). The model fits are encouraging enough to allow us to derive absolute luminosities for individual QSO's and to re-plot the Hubble Diagram with the values thus computed. We find a significantly improved fit to the expected unit slope in the plot of log z against 1/5(mB - MB), and a best fit value of qo = 0.1 (±0.4).
A Model for the Cosmological Evolution of Radio Sources
Authors: Subrahmanya C. R. , Kapahi V. K.
Published: June 2019

The existing schemes to express the evolution of radio sources are either too simple to fit all the data (multi-frequency counts, identifications, spectra etc.) or have too many parameters and little predictive value. They do not also fit the identification statistics at different flux-densities (Swarup, Subrahmanya & Kapahi 1982, in ‘Astrophysical Cosmology’, Proc. Vatican Study Week) and the counts from recent deep surveys (van der Laan 1982, in ‘Astrophysical Cosmology’). Here, we report a preliminary attempt to derive a model that retains the simplicity of a small number of parameters and ease of refinement when new data are added.
QSO Luminosities at λ 1 MM
Authors: Sherwood W. A.
Published: June 2019

The results discussed here are based on observations at λ 1 mm of 36 optically selected quasars (Sherwood et al., 1982; in preparation) and of 24 flat spectrum radio sources with Sν (5 GHz) ≥ 1 Jy (Kühr et al., 1979, 1981). H = 50 km/(s Mpc) and qo = 0 are used.
Unbiased Searches for Quasars Beyond a Redshift of 3.5
Authors: Savage Ann , Peterson Bruce A.
Published: June 2019

Nearly a decade elapsed between the discovery by Wampler at al. (1973) that the QSO OQ172 has a redshift of 3.53 and the discovery by Peterson et al. (1982) that the QSO Pks 2000–330 has a redshift of 3.78. During that time, radio and optical searches were vigorously pursued to find QSO's with redshifts greater than 3.5, but none were found. In this paper, we discuss selection effects in optical and radio searches and show how these selection effects have limited the redshift range of previous surveys. We propose a combination of radio and optical techniques that may be used to find high redshift QSO's and provide us with an undistorted view of the Universe beyond a redshift of 3.5.
JF Photometry of Fourteen Distant Rich Clusters of Galaxies
Authors: Couch W. J. , Newell E. B.
Published: June 2019

We have recently completed a photometric study of fourteen rich clusters of galaxies in the redshift range 0.18≤z≤0.39. The data are based on JF photographic photometry of each field. We report on the analysis of the cluster galaxy colour distributions; in particular we find that all the clusters in our sample with z ≳ 0.26 contain an excess number of blue galaxies (i.e., show the Butcher-Oemler effect). The blue excess, which was measured in terms of the ratio of the fraction of blue galaxies observed to that expected on the basis of Dressler's (1980) [morphological mix, local projected galaxy density]-correlations, ranges from 2 to ∼5. The highest value of 4.8 found in the cluster C10024+1654 (z=0.39), confirms Butcher and Oemler's (1978) observations of this cluster.
Spectral Energy Distributions of Galaxies in Moderate Redshift Clusters
Authors: Couch W. J. , Ellis R. S. , Godwin J. , Carter D.
Published: June 2019

We have observed 3 moderate redshift clusters using a combination of 7 intermediate band filters and 2 CCDs in order to derive photometric information for cluster galaxies from 400 nm to 900 nm. Preliminary results are presented for 2 clusters: Abell 1942 (z=0.224) and Abell 1525 (z=0.259) from 580 nm to 860 nm. The CCD photometry reaches a limit equivalent to RF=21 mag with a precision of better than 0.1 mag. The galaxy colours derived from the intermediate band measurements are generally consistent with those expected at the appropriate redshift. However, in Abell 1525, and to a lesser extent in Abell 1942, a large proportion of cluster members have far red (720–860 nm) colours redder than expected. Many of these galaxies have blue photographic BJ-RF colours. A possible explanation for the anomalous CCD colours is that these galaxies possess a strong emission line component which enters the far red filter at z=0.25.
New Limits to the Small Scale Fluctuations in the Cosmic Background Radiation
Authors: Kellermann K. I. , Fomalont E. B. , Wall J. V.
Published: June 2019

The VLA has been used at 4.9 GHz to observe a small region of sky in order to extend the radio source count to low flux density (Fomalont et al., these proceedings) and to look for small scale fluctuations in the 2.7 K cosmic microwave background radiation.
Quasars and Superclusters
Authors: Osmer Patrick S.
Published: June 2019

The topic of quasars and superclusters is only a few years old. Although the first pairs of quasars with small angular separations on the sky were found ten years ago (Stockton 1972, Wampler et al. 1973), the pair members had very different redshifts. The surface density of samples with available redshifts at that time was far too low for cases of quasars with both small angular separations and small redshift differences to turn up. Setti and Woltjer (1977) pointed out that if quasars occur in the nuclei of giant elliptical galaxies, then clustering should be apparent at 20th magnitude and fainter. In 1979 Walsh, Carswell and Weymann found a very close pair with identical redshifts; that, of course, was the first discovery of a gravitational lens. Also in 1979 Arp, Sulentic, and di Tullio showed that some of the quasars near NGC 3389 had similar redshifts, although at that time they did not discuss the hypothesis of the quasars being associated with superclusters. Subsequently Burbidge et al. (1980) confirmed that a compact (5 minutes of arc) group of 3 quasars found by Hoag on a 4m grating prism plate of the M82 field had very similar redshifts. Indeed, the group had the dimensions of a galaxy cluster, not a supercluster. Oort, Arp, and de Ruiter (1981) then specifically called attention to the fact that enough pairs of quasars with similar redshifts were known to suggest that quasar associations on the scale of galaxy superclusters do exist.
Dynamics of Voids and Clusters and Fluctuations in the Cosmic Background Radiation
Authors: Salpeter E. E.
Published: June 2019

I want to “make propaganda” for some calculations carried out at Cornell; a detailed paper is available on this work (Hoffman, Salpeter and Wasserman 1982, hereafter HSW), so I only summarize it briefly (Sect. 2) and concentrate mainly on implications. Like previous work by Peebles (1982) and by Occhionero et al (1982), these calculations use spherically symmetric models without dissipation for the dynamical development of large voids and galaxy clusters (and superclusters) from small underdensities and overdensities, respectively, at the recombination era. We now know how this development depends on various parameters and on the asymmetries between over- and under-densities. I discuss conjectures for more complex geometries in Sect. 3.
Substructure in Clusters of Galaxies
Authors: Geller M. J. , Beers T. C.
Published: June 2019

Rich galaxy clusters containing multiple condensations are common. This subclustering affects many cluster properties and provides insight into cluster evolution.

“Clumpy” clusters of galaxies are interesting, in part, because N-body simulations indicate that multi-component substructure occurs before complete collapse and virialization (White 1976). Interesting systems can be identified both from x-ray surface brightness maps (Forman et al. 1981) and from contour maps based on galaxy counts (Geller and Beers 1982).
The Kinematics of the Local Supercluster
Authors: Mould J. R. , Schechter P. L. , Aaronson M. , Tully R. B. , Huchra J. P.
Published: June 2019

The spatial distribution of galaxies in the Local Supercluster, as described at this meeting, together with the measured anisotropy in the microwave background suggest that there exist significant deviations from a uniform Hubble flow in the velocity field of galaxies within a few thousand km/s. In principle, it is not too hard to improve on the uniform flow model: one simply needs to examine the spatial distribution of the radial velocity residuals for many nearby galaxies. In practice, the problem is non-trivial because of the coupling of velocity and distance, and the lack of a distance indicator of high precision, and the “thermal” noise in the velocity field. Our recent efforts in this direction are described in more detail in a paper in a current Astrophysical Journal (Aaronson et al. 1982a).
Diameters of HI Disks in Virgo Cluster - and Field Galaxies
Authors: Warmels Rein H. , van Woerden Hugo
Published: June 2019

Environmental effects may be of great importance to the structure and evolution of galaxies. Sullivan and collaborators (1981, AJ 86, 919) find that the ratio between HI content and luminosity of galaxies tends to be smaller in regions of high galaxy density than elsewhere. It is not quite clear what processes reduce the gas content (or enhance the luminosity!): collisions, mergers or tidal interactions of galaxies, encounters with gas clouds, stripping by ram pressure? Detailed comparison of gas distributions and motions in cluster and field galaxies may help answer this question.
Evidence of Intrinsic Correlation Between the Luminosity and the Velocity Dispersion in Galaxy Groups
Authors: Mezzetti M. , Giuricin G. , Mardirossian F.
Published: June 2019

By using the two samples of galaxy groups reselected by Rood and Dickel (1979, Astroph. J. 233, 418), we have investigated the significance of the correlations between the virial parameters of groups. Taking into account observational selection effects present in the two samples, together with statistical and observational uncertainties, we show that only an intrinsic correlation between the luminosity L and velocity dispersion V is necessarily required in order to explain all the observed correlations. There is no serious ground to state that the virial radius correlates with both velocity dispersion and luminosity. We also show that the observed slope of the Log L - Log V relation is considerably smaller than the true slope, while the contrary holds for the Log M/L - Log V relation.

An analysis similar to that described above, carried on the recent catalogue of nearby groups of galaxies prepared by Huchra and Geller (1982, Astroph. J. 257, 423), seems to reveal that also the intrinsic correlations between L and R, and R and V are significant for this new sample.
Structure of Neighboring Superclusters: A Quantitative Analysis
Authors: Einasto J. , Klypin A. , Shandarin S.
Published: June 2019

So far the galaxy correlation analysis was the only quantitative method used to describe the distribution of galaxies in space. Here we consider other numerical methods to treat impersonally various aspects of the galaxy distribution.
What does the Dynamical Analsis of Clusters of Galaxies Tell us About Massive Neutrinos?
Authors: Des Forêts G. , Gerbal D. , Mathez G. , Mazure A. , Salvador-Solé E.
Published: June 2019

It is often claimed that massive neutrinos (v's) can solve the “missing mass” problem, but it is not so clear in the particular case of clusters of galaxies (C.O.G.). Let us assume that the unseen matter is composed by massive v's only. If they are cosmological, the v's should obey Fermi-Dirac statistics with a density of ∼ 100 v/cm3/species. But if “relic,” the v's would be so slow (1) that they cannot exist in this form (because of the previous Jeans instability or because they are trapped in wells generated by baryonic matter). Since the time when the v's decoupled from the primeval mixture (T ∼ 3–1 MeV), the v's can be considered as a “gravitational plasma,” so that violent relaxation occurs in inhomogeneous systems, leading to a Lynden-Bell distribution defined by three parameters: ην (numerical density), Vv (r.m.s. velocity) and the v-mass, mv, all unknown. All three of these parameters are, in fact, necessary to define a state of v-matter.
The [

AN

] Isotropy of the X-Ray Sky
Authors: Shafer R. A. , Fabian A. C.
Published: June 2019

In this presentation we show how the study of the isotropy of the X-ray sky contributes to our understanding of the structure of the universe at moderate redshifts (1≲z<<zrecombination). Actually, the anisotropy of the sky flux provides the information, much as the microwave sky anisotropy does for earlier epochs. [See reports in this volume.] Though we are currently unable to make measurements with the precision and small solid angles typically achieved in the microwave, comparatively crude limits from the X-ray fluctuations place limits on the largest scale structure of the universe. We first outline the measurements of the X-ray sky and its anisotropies made with the HEAO 1 A-2 experiment. Detailed presentations are found elsewhere [Shafer 1982; Marshall et al. 1980; Piccinotti et. al. 1982; Iwan et al. 1982; Shafer et al. in prep.]. We then show how the anisotropies place limits on the origin of the X-ray sky and on any large scale structure of the universe, following the example of previous analyses which used earlier anisotropy estimates [see e.g. Fabian and Rees 1978; Rees 1980; Fabian 1981].
Are QSOs Gravitationally Lensed?
Authors: Tyson J. A.
Published: June 2019

There are now four known cases of multiply imaged QSOs, one with a detected foreground object at roughly half the affine distance to the QSO: 0957+561 (17 mag, z=1.4, separation =6″), 1115+080 (17 mag, z=1.7, sl=1.8″, s2=2.3″), 2345+007 (19 mag, z=2.1, s=7″) and 1635+267 (19 mag z=2, s=5″). In addition, 1548+115 (19 mag, z=1.9) is a probable lens event with a foreground QSO, but no secondary image has been found. Perhaps 500 candidate QSOs have been surveyed optically for multiple images by all observers. 0957+561 is the only catalogued QSO shown to be multiple. Of the remaining 1548 QSOs currently catalogued, any secondary image is masked by atmospheric scattering of the QSO light. Typically, this sets detection limits of ≳ 3 mag fainter and < 2 arcsec separation from the bright component, for any secondary image. Objective prism and grism surveys look directly for multiple QSOs with identical emission lines and have surveyed 1500 QSOs. The remaining three lensed QSOs come from these more efficient surveys. Although the exciting search for multiply imaged QSOs has only begun, sufficient data already exist to test two hypotheses: (A) QSOs are intrinsically luminous and occasionally are multiply imaged through a chance alignment with a foreground galaxy of sufficient mass gradient and (B) all QSOs are the result of gravitational lens magnification of a distant Seyfert nucleus by foreground galaxy(s). I will first address hypothesis B, then A. I assume that mass (seen and unseen) clusters with galaxies and/or clusters of galaxies.
The Theory of Large-Scale Structure of the Universe: Local Properties and Global Topology
Authors: Doroshkevich A. G. , Shandarin S. F. , Zeldovich Ya.B.
Published: June 2019

Properties of the large-scale distribution of galaxies are considered. Particular attention is paid to properties of the large-scale structures such as anisotropy of superclusters and the existence of large regions practically devoid of galaxies. Another question discussed in detail is the link between superclusters and formation of a network or cellular structure. An explanation of the latter is proposed in the frame of the fragmentation scenario. The role of the neutrino rest mass is discussed.
Self-Similar Gravitational Clustering
Authors: Efstathiou G.
Published: June 2019

The nature of the distribution of galaxies poses a challenging problem for theorists. It seems reasonable, as a start, to suppose that galaxies and clusters arose from small perturbations by gravitational instability. However, one still has the problem of the choice of initial conditions, for example, the shape of the fluctuation spectrum and the cosmological density parameter Ω. A considerable simplification is to assume that the clustering pattern obeys some simple similarity scaling, so that the clustering at some early time, apart from a change in length scale, is statistically indistinguishable from the pattern observed today. The power-law shape of the two-point correlation function and the simple forms of higher order correlation functions (Peebles, 1980) have provided some evidence that such a simplifying assumption may be relevant - just how relevant is the subject of this article.
Neighboring Superclusters and Their Environs
Authors: Einasto J. , Miller R. H.
Published: June 2019

Recently finished redshift surveys make it possible to study the large-scale environment of superclusters and their mutual relationship.

Figure 1 shows the distribution of nearby clusters in the sky in supergalactic coordinates at two redshift intervals. Nearby clusters in the distance interval 75 to 150 Mpc form a belt around us which is close to the supergalactic equator; its inclination is only 20°. The following superclusters belong to this belt: Ursa Major-Lynx (Giovanelli and Haynes 1982), Coma, Hydra-Centaurus, Pavo-Corona Australes, and Perseus-Pisces. Coordinates and redshifts for a number of previously unknown southern clusters have been derived by Dr. H. Corwin and Dr. M. Tarenghi (Einasto et al. 1982).
Spherical and Toroidal Local Black Holes
Authors: Xanthopoulos Basilis C.
Published: June 2019

The local black holes describe physical situations involving a black hole surrounded by a finite vacuum region and then by matter and fields. The stationary and axisymmetric local black holes belong into two classes, the spherical and the toroidal ones, depending on the topology of their horizon. For the static black holes their metric tensors are given explicitly in terms of Legendre polynomials. For the stationary local black holes the problem is formulated interms of the Ernst potential of the rotational Killing field and the appropriate asymptotic conditions on the horizon are determined.
Acceleration and Dissolution of Stars in the Antibang
Authors: Harrison E. R.
Published: June 2019

If the universe is spatially closed, and the simplest cosmological models are valid approximations, then in ∼ 1011 years the universe will recollapse into an antibang. (A “bang” is explosive, whereas an “antibag” may be considered implosive.) In this note I shall add one or two details to the seminal work of Rees (1969).
Unified Gauge Theories and Galaxy Formation
Authors: Lazarides G.
Published: June 2019

Grand Unified strings may provide us with the primordial density fluctuations needed for galaxy formation. The properties and the cosmological evolution of such strings are discussed. A Grand Unified Theory with strings is constructed.
R2 Gravity and the Structure of the Universe
Authors: Brecher Kenneth
Published: June 2019

The “standard” hot big bang model accounts for the expansion of the Universe, the existence of the microwave background radiation, and the mass fraction of the light elements up to 4He. It does not account for the high degree of isotropy and homogeneity of the Universe in the large, nor of the existence of structure (galaxies, clusters) on smaller scales. Other problems, such as the lepton to baryon ratio, the preponderance of matter over antimatter, and the “coincidences” of dimensionless ratios of several fundamental physical and cosmological “constants” also lie outside of the “standard” model at present.
The Role of Particle Physics in Cosmology and Galactic Astronomy
Authors: Sciama D. W.
Published: June 2019

A non-technical introduction is given to (a) the inflationary universe, (b) the production of baryon asymmetry by GUTs, (c) the possible role of massive neutrinos and (d) the possible role of the massive photinos and goldstinos of broken supersymmetric theories.
Blue Clusters, Populous Clusters, and Globulars
Authors: Hodge Paul W.
Published: June 2019

The introduction of new photometric techniques for faint objects has tremendously increased our understanding of the MC clusters, especially at the old end of the age spectrum. Many of the well-studied clusters of the past have gone through several transformations, starting as true globulars in 1960, becoming intermediate-age objects in the 1970's, but now returning to the true globular classification in the 1980's. LW 868 is an example of a cluster with such a history. Better photometric accuracy is also greatly improving our understanding of younger clusters, allowing detailed comparisons with theoretical evolutionary models, and a more reliable determination of the age-abundance relationship. The dynamical history of MC clusters can also be examined from the new data. The cluster formation rate, as well as the destruction rate, can be reconstructed from modern, deep cluster surveys.