Statistical Analysis Of The Properties Of GRB Host Galaxies

In this paper, we briefly summarize both the observational and theoretical progress of Gamma-Ray Bursts (GRBs) in recent years, focusing on the research progress of the GRB host galaxies. Then, we present the results of our investigation for the statistical properties of GRB host galaxies.Both GRB and afterglow observations provide important clues to their progenitors and host galaxies. It is well believed that long GRBs are originated from the collapse of massive stars and short GRBs are from compact star merger s. Host galaxies observations well supports this framework. Long GRB host galaxy is generally faint, blue, low-mass, low-metallicity of star formation galaxy. However the types of the short GRB host galaxies are more complex, but also mainly are the star formation galaxies. There are nearly200observed GRB host galaxies. We present a systematical analysis on the statistical properties of the long GRB host galaxies. We found that:(1)A correlation between the metallicity of a GRB host galaxy and its stellar masses is observed, showing that the total stellar mass plays an important role in the chemical evolution of host galaxy;(2) SSFR (Specific Star Forming Rate) and stellar mass is anti-correlation, suggesting that the galaxy star formation activities with increasing of its stars mass is restrained because intergalactic gravitational tides and merger effect will affect the galaxy’s Star formation activities;(3)The star formation rate (SFR) and stellar mass has a positive correlation, which is consistent with that from non-GRB host galaxies, evidencing that GRB host galaxies are not distinct from general galaxies;(4)A very weak relationship between extinction of GRB hosts and stellar mass is observed, indicating that the extinction would be not closely to GRB host galaxy intrinsic properties (stellar mass)1;(5)No clear relation between GRB host galaxy extinction and X ray hydrogen column density is found. We also explore the cosmological evolution of the properties of GRB host galaxies. We show the SFR, stellar mass, metallicity and host galaxy extinction as a function of redshift. It is found that the SFR increases as the redshift increases. High-z host galaxies (1<z<6.3) tends to have a higher average star mass than the nearly host galaxy (0.007<z<1). No cosmic evolution is found for the metallicity and the extinction.