Gamma Ray Burst Host Galaxies Have `Normal' Luminosities

Abstract

The galactic environment of Gamma Ray Bursts can provide good evidence about the nature of the progenitor system, with two old arguments implying that the burst host galaxies are significantly subluminous. New data and new analysis have now reversed this picture: (A) Even though the first two known host galaxies are indeed greatly subluminous, the next eight hosts have absolute magnitudes typical for a population of field galaxies. A detailed analysis of the 16 known hosts (ten with red shifts) shows them to be consistent with a Schechter luminosity function with $R^{\ast }=-21.8\pm 1.0$ as expected for normal galaxies. (B) Bright bursts from the Interplanetary Network are typically 18 times brighter than the faint bursts with red shifts, however the bright bursts do not have galaxies inside their error boxes to limits deeper than expected based on the luminosities for the two samples being identical. A new solution to this dilemma is that a broad burst luminosity function along with a burst number density varying as the star formation rate will require the average luminosity of the bright sample ($>$$6\times 10^{58}ph\cdot s^{-1}$ or $>$$1.7\times 10^{52}\cdot erg\cdot s^{-1}$) to be much greater than the average luminosity of the faint sample ($\sim 10^{58}ph\cdot s^{-1}$ or $\sim 3\times 10^{51}erg\cdot s^{-1}$). This places the bright bursts at distances for which host galaxies with a normal luminosity will not violate the observed limits. In conclusion, all current evidence points to GRB host galaxies being normal in luminosity.

18 pages, 3 figures, Submitted to ApJLett

References in corpus (2)

• The Radio Afterglow and the Host Galaxy of the X-Ray Rich GRB 981226
• Discovery of the Optical Transient of the Gamma Ray Burst 990308

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• Neutrino, Neutron, and Cosmic Ray Production in the External Shock Model of Gamma Ray Bursts
• GRB 010222: A Burst Within a Starburst
• Luminosity Function of GRBs
• Are There Any Redshift >8 Gamma-Ray Bursts in the BATSE Catalog?