Spatial Distribution Of Gamma-ray Bursts Research Articles

The Spatial Distribution of Gamma-Ray Bursts with Measured Redshifts from 24 Years of Observation

Gamma-ray bursts (GRBs) are the most luminous objects known: they outshine their host galaxies, making them ideal candidates for probing large-scale structure. Our aim is to determine the Spatial Two-Point Correlation Function of the GRBs with spectroscopic redshifts. We used all observations till 4 June 2021, and we also split the data according to the origin of the redshift (afterglow or host galaxy). We analyzed the possible correlation between the GRB redshift and sky position. There is only one region, called the Faraway GRB Patch, where nine distant GRBs shows deviation from the randomness with an ≈1% significance, showing that the sky and the radial component of the GRB distribution could be factorized and both can be determined independently. The GRBs’ cumulative monthly distribution was used to show that it is impossible to synthesize the Sky Exposure Function, even from the perfect observational logs. We estimated the Sky Exposure Function using the Gaussian kernel, and with the radial distribution, it was used for the estimation of the Spatial Two-Point Correlation Function. Monte Carlo simulations were used to determine the Poissonian errors. Our result shows that the current Spatial Two-Point Correlation Function estimations are consistent with zero for the full and the afterglow/host galaxy datasets.

New data support the existence of the Hercules-Corona Borealis Great Wall

Several large structures, including the Sloan Great Wall, the Huge Large Quasar Group, and a large gamma-ray burst cluster referred to as the Hercules-Corona Borealis Great Wall, appear to exceed the maximum structural size predicted by Universal inflationary models. The existence of very large structures such as these might necessitate cosmological model modifications. Gamma-ray bursts are the most luminous sources found in nature. They are associated with the stellar endpoints of massive stars and are found in and near distant galaxies. Since they are viable indicators of the dense part of the Universe containing normal matter, the spatial distribution of gamma-ray bursts can serve as tracers of Universal large-scale structure. An increased sample size of gamma-ray bursts with known redshift provides us with the opportunity to validate or invalidate the existence of the Hercules-Corona Borealis Great Wall. Nearest-neighbour tests are used to search the larger sample for evidence of clustering and a bootstrap point-radius method is used to estimate the angular cluster size. The potential influence of angular sampling biasing is studied to determine the viability of the results. The larger gamma-ray burst database further supports the existence of a statistically significant gamma-ray burst cluster at 1.6 < z < 2.1 with an estimated angular size of 2000-3000 Mpc. Although small number statistics limit our angular resolution and do not rule out the existence of adjacent and/or line-of-sight smaller structures, these structures must still clump together in order for us to see the large gamma-ray burst cluster detected here. This cluster provides support for the existence of very large-scale universal heterogeneities.

Possible structure in the GRB sky distribution at redshift two

Context. Research over the past three decades has revolutionized cosmology while supporting the standard cosmological model. However, the cosmological principle of Universal homogeneity and isotropy has always been in question, since structures as large as the survey size have always been found each time the survey size has increased. Until 2013, the largest known structure in our Universe was the Sloan Great Wall, which is more than 400 Mpc long located approximately one billion light years away. Aims. Gamma-ray bursts are the most energetic explosions in the Universe. As they are associated with the stellar endpoints of massive stars and are found in and near distant galaxies, they are viable indicators of the dense part of the Universe containing normal matter. The spatial distribution of gamma-ray bursts can thus help expose the large scale structure of the Universe. Methods. As of July 2012, 283 GRB redshifts have been measured. Subdividing this sample into nine radial parts, each containing 31 GRBs, indicates that the GRB sample having 1.6 < z < 2.1 differs significantly from the others in that 14 of the 31 GRBs are concentrated in roughly 1/8 of the sky. A two-dimensional Kolmogorov-Smirnov test, a nearest-neighbour test, and a Bootstrap Point-Radius Method explore the significance of this clustering. Results. All tests used indicate that there is a statistically significant clustering of the GRB sample at 1.6 < z < 2.1. Furthermore, this angular excess cannot be entirely attributed to known selection biases, making its existence due to chance unlikely. Conclusions. This huge structure lies ten times farther away than the Sloan Great Wall, at a distance of approximately ten billion light years. The size of the structure defined by these GRBs is about 2000-3000 Mpc, or more than six times the size of the Sloan Great Wall.

Observed properties of gamma-ray bursts

The observed temporal and spectral characteristics and the spatial distribution of gamma-ray bursts (GRBs) are summarized, primarily from data obtained with the BATSE experiment on the Compton Observatory. The availability of these data and the prospects for continued observations are also described.

The distribution of old neutron stars in the galaxy

The distribution of old galactic neutron stars is computed for model galactic potential and initial neutron star velocity distribution following from evolution scenario of binary systems. Neutron stars are supposed to get their initial velocities during (asymmetric) supernova explosion of a single massive (M,, > 10 Ma) star or a massive component of a binary system. Old neutron star population is shown to be capable of filling a torus-like area extending to a few tens kiloparsecs above the galactic plane. Statistical tests related to the spatial distribution of gamma-ray bursts are carried out for the distribution obtained. Recent results from the BATSE device onboard the GRO observatory have shown a full isotropy of gamma-ray burst locations the sky and their inhomogeneous spatial density (( V/V,,,) = 0.33 f 0.02, (sin2 6) = 0.31 f 0.02, (cos 0) = 0.008 f 0.035) (Meegan et al., 1992), where 0 is the angle between the source and the galactic center, b is the galactic latitude and ( ) denotes averaging over the whole sample. In the case of a purely homogeneous, isotropic distribution these quantities would be, respectively 1/2, 1/3 and 0. These observed statistical features of gamma-bursts greatly reinforced interest to the nature of their possible progenitors. An attractive possibility of old galactic neutron stars looses its credibility, especially in view of negative results of searching for any spectral feature in the gamma-burst spectra obtained by BATSE. Some indications appear that gamma-ray bursts can be divided into at least two types: the strong bursts having hard spectra, with (V/Vm,,) > 1/2 and the weaker ones with softer spectra and (V/V,,,) < 1/2 (APEX experiment results, Mitrofanov et al., 1992; see also Lingenfelter & Higdon, 1992). These results might indicate that two populations of gamma-ray burst progenitors having different spatial distributions actually exist, viz. that producing weak bursts and lying outside the galactic disc, and that producing stronger bursts and residing in the galactic disc. Brainerd (1992) has shown that the BATSE results can be reconciliated with the old neutron star paradigm if one considers an extended (2100 kpc) halo consisting of old neutron stars. The question arises, whether there is any mechanism of natural populating such a halo by old neturon stars? The spatial distribution of old galactic neutron stars as putative gamma-ray burst progenitors has been studied earlier (e.g. Paczynski, 1990; Hartmann et al.,

The spatial distribution of gamma-ray bursts from Pioneer Venus Orbiter

view Abstract Citations (21) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Spatial Distribution of Gamma-Ray Bursts from Pioneer Venus Orbiter Chuang, K. W. ; White, R. S. ; Klebesadel, R. W. ; Laros, J. G. Abstract The homogeneity of the burst source population in space with the log N(greater than Pc)-log Pc and log (dN/dPc)-log Pc relations is studied on the basis of a sample of 225 observed gamma-ray bursts between September 1978 and July 1988 from the Pioneer Venus Orbiter. The relations N(greater than Pc) is approximately equal to Pc exp -1.5 and dN/dPc is approximately equal to Pc exp -2.5 are expected if the gamma bursters are uniformly distributed in space. The Kolmogorov-Smirnov statistic gives a probability of 0.93 that the observed integral distribution N(greater than Pc) is drawn from the expected uniform distribution Pc exp -1.5. A least-squares 1 standard deviation fit to the observed differential distribution yields dN/dPc of about Pc -2.42 +/- 0.07. Both are consistent with a uniform distribution in space of the parent population of burst sources. Publication: The Astrophysical Journal Pub Date: May 1992 DOI: 10.1086/171340 Bibcode: 1992ApJ...391..242C Keywords: Gamma Ray Bursts; Pioneer Venus 1 Spacecraft; Spatial Distribution; Background Radiation; Least Squares Method; Radiation Detectors; Statistical Analysis; Space Radiation; GAMMA RAYS: BURSTS; STARS: STATISTICS full text sources ADS |

Distribution of intensities of gamma-ray bursts

The authors propose that at log N - log n<SUB>max</SUB> relation should be used for studies of the spatial distribution of gamma-ray bursts, where N is the number of bursts which have a maximum photon count rate in excess of n<SUB>max</SUB>. A relation N ≡ n<SUB>max</SUB><SUP>-1.5</SUP> is expected if the sources are uniformly distributed in infinite, flat space, regardless of the distribution of intrinsic luminosities, spectra, and time profiles. Bursts in the Konus catalog follow a relation N ≡ n<SUB>max</SUB><SUP>a</SUP>, with the most probable value a = -1.2. However, a = -1.5 is also acceptable. This result and the apparently isotropic distribution of ≡10<SUP>2</SUP> bursts over the sky do not allow a purely observational distance estimate for the sources.