Long-duration X-ray flash and X-ray-rich gamma-ray bursts from low-mass population III stars

Abstract

Recent numerical simulations suggest that Population III (PopIII) stars were born with masses not larger than 100 M and typically 40 M. By self-consistently considering the jet generation and propagation in the envelope of these low-mass PopIII stars, we find that a PopIII blue supergiant star has the possibility of giving rise to a gamma-ray burst (GRB) even though it keeps a massive hydrogen envelope. We evaluate observational characteristics of PopIII GRBs and predict that PopIII GRBs have a duration of 105s in the observer frame and a peak luminosity of 5 × 1050 erg s -1. Assuming that the E p-L p (or E p-E γ, iso) correlation holds for PopIII GRBs, we find that the spectrum peak energy falls at approximately a fewkeV (or 100keV) in the observer frame. We discuss the detectability of PopIII GRBs by future satellite missions such as EXIST and Lobster. If the E p-E γ, iso correlation holds, we have the possibility to detect PopIII GRBs at z 9 as long-duration X-ray-rich GRBs by EXIST. Conversely, if the E p-L p correlation holds, we have the possibility to detect PopIII GRBs up to z 19 as long-duration X-ray flashes by Lobster. © 2012. The American Astronomical Society. All rights reserved.