摘要:

The GRB angular/intensity distributions observed by BATSE greatly constrain models of the spatial and luminosity source distributions. Single populations of Galactic Disk and Galactic Halo sources appear to be untenable, and only a limited subset of models made up of sources in a symmetric Galactic Corona satisfy the observations. Comments are made on other classes of models.

ISSN:0094-243X    

DOI:10.1063/1.42780

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The new interplanetary gamma‐ray burst network will determine source fields with unprecedented accuracy. The baseline of the Ulysses mission and the locations of Pioneer‐Venus Orbiter and of Mars Observer will ensure precision to a few tens of arc seconds. Combined with the event phenomenologies of the Burst and Transient Source Experiment on Compton Observatory, the source locations to be achieved with this network may provide a basic new understanding of the puzzle of gamma ray bursts.

ISSN:0094-243X    

DOI:10.1063/1.42781

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The &ggr;‐ray telescope COMPTEL onboard GRO has so far located 6 gamma‐ray bursts which occurred in its ∼1 sr field of view. The positions of the sources were derived by the maximum‐entropy method. Systematic and statistical uncertainties for the four strongest bursts are approximately 1° to 2° and can be reduced in future analysis.

ISSN:0094-243X    

DOI:10.1063/1.42782

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The angular distribution of gamma‐ray bursts on the sky and their intensity distribution are important tools for our understanding of the nature of these enigmatic phenomena. We discuss here some properties of these quantities with an emphasize on the influence of instrumental parameters. We also check the consistency of the statistical properties of three GRB samples (KONUS, SIGNE and BATSE) which have been discussed individually but not compared together.

ISSN:0094-243X    

DOI:10.1063/1.42783

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We applied theV/Vmaxtest to a sample of 132 candidate cosmic gamma‐ray bursts to determine quantitatively the spatial uniformity of the burst source population. We found (V/Vmax)=0.40±0.025, significantly different from 0.5, the value expected for a uniform distribution. The shape of ourV/Vmaxdistribution is approximately flat except for the lowest bin belowV/Vmaxof 0.05. We examined monoluminosity galactic disk and massive halo populations as possible sources for these candidate bursts. For these populations we found that, to reproduce ourV/Vmaxdistribution, burst sky locations should be highly anisotropic, concentrated towards the galactic plane with dipole moments ≊0.4 to 0.7.

ISSN:0094-243X    

DOI:10.1063/1.42784

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

In these general remarks, we first recall that in radio astronomy, isotropy and source counts steeper than the Euclidean value of −1.5 provided early evidence for the cosmological nature of radio sources. We discuss briefly whether anything can be wrong with the evidence for isotropy and a non‐uniform distribution of GRBs. We identify the selection of cosmic GRBs among recorded bursts and their isotropy as the weaker part of the evidence. We suggest a way to relate the various ⟨V/Vmax⟩ values to each other. We point out that the strong concentrations of smallV/Vmaxvalues fits well with a uniform distribution of sources out to a redshift of about 2, but note that sources observed at these redshifts generally exhibit evolution, i.e., a non‐uniform space distribution.

ISSN:0094-243X    

DOI:10.1063/1.42785

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The distribution ofV/Vmof gamma‐ray bursts (GRB) observed by BATSE on GRO1shows a steep increase of the number of bursts with decreasing value of theV/Vm. This is in contrast to earlier analyses (e.g., refs. 2 and 3) which show a relatively flat distribution ofV/Vmbetween zero and one as expected from a homogeneous distribution of sources in an (infinite) Euclidean space. Introduction of theV/Vmmethod by Schmidt in analysis of the GRB count data has greatly clarified the interpretation of these data. However, there are still some misunderstandings and the purpose of these comments is to clarify some points and make some predictions about what we shall expect in the rest of the life of GRO about the distribution of the GRBs.

ISSN:0094-243X    

DOI:10.1063/1.42786

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We revise the method proposed some years ago to evaluate the luminosity function of cosmic Gamma‐Ray Bursts on the basis of the log N‐log Pbehavior, wherePis the peak intensity. The method is valid in the hypothesis that a correlation between the intensity and the peak temperature (energy spectral hardness) exists as suggested by various authors. We believe that in the near future it will be possible to test the method in a conclusive manner using the results of recent space missions (like GRO, Granat and Ulysses).

ISSN:0094-243X    

DOI:10.1063/1.42826

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

If the BATSE instrument is a few times more sensitive than previously flown detectors, the value of (sin2 b) measured by BATSE may be in agreement with a model in which the gamma‐ray bursts are distributed uniformly in a disk. The value of ⟨V/Vmax⟩ predicted by that model is higher than the one reported by BATSE, but the statistical error is hard to asses when the actual value if different from 0.5. A two dimensional analogue of the ⟨V/Vmax⟩ test would be more useful in testing disk models.

ISSN:0094-243X    

DOI:10.1063/1.42827

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The Pioneer Venus Orbiter (PVO) logN‐log Pdistribution follows a −3/2 power law for over a factor of 30 in intensity, which is inconsistent with Gamma‐Ray Bursts from large redshifts. We develop log N‐log Pmodels suitable for cosmological gamma‐ray bursts. The PVO data is best fit with a standard candle peak luminosity of 2×1050erg/sec with 3×104events/yr within a Hubble distance. However, non‐cosmological models fit nearly as well (L0≪1050). A luminosity of 1052erg/sec fits at a 3&sgr; level and is, therefore, a maximum upper limit allowed by the PVO data. This upper limit is roughly equal to other reported lower limits. The BATSE event rate combined with the PVO limits imply that evolution with epoch must be occurring.

ISSN:0094-243X    

DOI:10.1063/1.42828

出版商:AIP    

年代:1991

数据来源: AIP