Dark burst of gamma rays

A dark gamma ray burst ( English dark GRB ) is a gamma ray burst of which no afterglow in the optical / infrared radiation range is observed or the afterglow in the optical is very low in relation to the X-ray luminosity. About 20 percent of all gamma ray bursts are dark gamma ray bursts.

Gamma ray bursts are bursts with high power in the range of hard gamma radiation that can be detected over extragalactic distances . They are interpreted as the result of a highly relativistic bundled jet . In the case of long gamma ray bursts in particular, afterglow can be observed in other areas of the electromagnetic spectrum , from X-rays to radio radiation. This is interpreted as an interaction of the ejected particles with the interstellar matter around the location of the gamma ray burst after the jet speed has already been slowed down or as synchrotron radiation from electrons in the magnetic field of the GRB. With the dark gamma ray bursts, which make up about 20 percent of all gamma ray bursts, no afterglow or only very little afterglow compared to the X-ray luminosity can be detected.

The causes of the dark gamma-ray bursts are thought to be:

• Observation error
• High extinction within the GRB's home galaxy
• Lyman alpha cut-off for high redshift gamma-ray bursts
• Intrinsic gamma ray bursts with a low optical luminosity of the afterglow

The first three hypotheses are probably the cause of some of the gamma ray bursts, since GRBs with a very high redshift show a disproportionately large number of dark gamma ray bursts and the nearby Dark GRBs often occur in starburst galaxies . In starburst galaxies, the star formation rate is very high and the resulting dust absorbs the electromagnetic radiation of the afterglow in the optical and near infrared. It is unclear whether there are also intrinsically dark gamma rays.

Examples of dark gamma-ray bursts are:

• GRB 130528A
• GRB 100615A
• GRB 100614A
• GRB 080207
• GRB 970828

literature

• S. Jeong et al .: The dark nature of GRB 130528A and its host galaxy . In: Astrophysics. Solar and Stellar Astrophysics . 2014, arxiv : 1404.0939v1 (English).
• BA Zauderer et al .: Illuminating the Darkest Gamma-Ray Bursts with Radio Observations . In: Astrophysics. Solar and Stellar Astrophysics . 2012, arxiv : 1209.4654v1 (English).
• Dong Zhang, KZ Stanek: The Very Massive and Hot LMC Star VFTS 682: Progenitor of a Future Dark Gamma-Ray Burst? In: Astrophysics. Solar and Stellar Astrophysics . 2011, arxiv : 1112.0016v2 (English).
• KM Svensson et al .: The dark GRB080207 in an extremely red host and the implications for GRBs in highly obscured environments . In: Astrophysics. Solar and Stellar Astrophysics . 2011, arxiv : 1109.3167v1 (English).
• Gu-Jing Lv et al .: Effect of Dust Extinction on Gamma-ray Burst Afterglows . In: Astrophysics. Solar and Stellar Astrophysics . 2011, arxiv : 1108.4930v1 (English).
• V. D'Elia, G. Stratta: GRB 100614A and GRB 100615A: two extremely dark GRBs . In: Astrophysics. Solar and Stellar Astrophysics . 2011, arxiv : 1108.1077v1 (English).