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Batse observations of the large-scale isotropy of gamma-ray bursts
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Fishman, Gerald J. Paciesas, William S. Hartmann, Dieter H. Brock, Martin N. Meegan, Charles A. Hakkila, Jon Pendleton, Geoffrey N. Kouveliotou, Chryssa Horack, John M. Briggs, Michael S. |
| Copyright Year | 1996 |
| Description | We use dipole and quadrupole statistics to test the large-scale isotropy of the first 1005 gamma-ray bursts observed by the Burst and Transient Source Experiment (BATSE). In addition to the entire sample of 1005 gamma-ray bursts, many subsets are examined. We use a variety of dipole and quadrupole statistics to search for Galactic and other predicted anisotropies and for anisotropies in a coordinate-system independent manner. We find the gamma-ray burst locations to be consistent with isotropy, e.g., for the total sample the observed Galactic dipole moment (cos theta) differs from the value predicted for isotropy by 0.9 sigma and the observed Galactic quadrupole moment (sin(exp 2) b - 1/3) by 0.3 sigma. We estimate for various models the anisotropies that could have been detected. If one-half of the locations were within 86 deg of the Galactic center, or within 28 deg of the Galactic plane, the ensuing dipole or quadrupole moment would have typically been detected at the 99% confidence level. We compare the observations with the dipole and quadrupole moments of various Galactic models. Several Galactic gamma-ray bursts models have moments within 2 sigma of the observations; most of the Galactic models proposed to date are no longer in acceptable agreement with the data. Although a spherical dark matter halo distribution could be consistent with the data, the required core radius is larger than the core radius of the dark matter halo used to explain the Galaxy's rotation curve. Gamma-ray bursts are much more isotropic than any observed Galactic population, strongly favoring but not requiring an origin at cosmological distances. |
| File Size | 2286741 |
| Page Count | 26 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19970023057 |
| Archival Resource Key | ark:/13960/t52g2nt3f |
| Language | English |
| Publisher Date | 1996-03-01 |
| Access Restriction | Open |
| Subject Keyword | Astronomy Neutron Stars Statistical Analysis Galaxies Gamma Ray Observatory Rotation Gamma Ray Bursts Quadrupoles Halos Dark Matter Anisotropy Astronomical Models Cosmology Dipole Moments Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
