Redshift catalog of swift long GRBs

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Conference Proceeding

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The redshifts of long-duration Gamma-Ray Bursts (GRBs) remain an important issue, and unfortunately only 30% of GRBs have redshifts from optical spectroscopy. The redshifts for most of the remaining 70% can be determined with useful accuracy by means of several luminosity relations, wherein some measurable light curve or spectral property (e.g., spectral lag zlag or peak energy of the spectrum Epeak) is well correlated with the burst luminosity. The idea is to use these luminosity relations, along with some adopted cosmology, to measure the redshift of bursts without optical spectroscopy. We apply this procedure to all long-duration Swift bursts up to 2008, July 23 (GRB080723A), with accurately propagated error bars. We present the redshift distribution from our catalog for these Swift bursts. Our complete catalog can be used for various demographic studies (without the complex selection effects of optical spectroscopy). From our results we see that the spectroscopic redshifts have been biased to z < 2, and by using all the detected bursts, we are getting rid of the spectroscopic selection effect. We applied our method on the recent discovered high redshift burst GRB080913 (with z = 6.7). We found that it fits all the luminosity relations perfectly well, and our derived redshift (z = 6.3+12.3-3.4) agrees with its spectroscopic redshift. © 2009 American Institute of Physics.

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AIP Conference Proceedings

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