On the Prospects of Gamma-Ray Burst Detection in the TeV Band

Journal Article · Sun Sep 10 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA7DDB· OSTI ID:22875815

Vurm, Indrek; Beloborodov, Andrei M. ^[1]

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1. Physics Department and Columbia Astrophysics Laboratory, Columbia University, 538 West 120th Street, New York, NY 10027 (United States)

A gamma-ray burst (GRB) jet running into an external medium is expected to generate luminous GeV–TeV emission lasting from minutes to several hours. The high-energy emission results from inverse Compton upscattering of prompt and afterglow photons by shock-heated thermal plasma. At its peak the high-energy radiation carries a significant fraction of the power dissipated at the forward shock. We discuss in detail the expected TeV luminosity, using a robust “minimal” emission model. Then, using the statistical properties of the GRB population (luminosity function, redshift distribution, afterglow energy), we simulate the expected detection rates of GRBs by current and upcoming atmospheric Cherenkov instruments. We find that GRBs exploding into a low-density interstellar medium must produce TeV emission that would have already been detected by the currently operating Cherenkov telescopes. The absence of detections is consistent with explosions into a dense wind of the GRB progenitor. If, as suggested by the recent analysis of Fermi LAT data, the typical environment of long GRBs is a Wolf–Rayet progenitor wind with the density parameter A∼10{sup 11} g cm{sup −1}, then 10%–20% of the bursts that trigger the space-borne detectors should also be detectable by the upcoming Cherenkov Telescope Array (CTA) under favorable observing conditions. Since absorption by the extragalactic background light limits the detectability above 0.1 TeV for all but the most nearby bursts (z≲1), the reduced energy threshold of CTA is the key improvement over current instruments, which should increase the number of detectable bursts by at least a factor of 3 compared with currently operating facilities.

• OSTI ID: 22875815
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 846; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
AFTERGLOW
COMPARATIVE EVALUATIONS
COSMIC GAMMA BURSTS
DENSITY
DETECTION
DISTRIBUTION
EMISSION
GEV RANGE
LUMINOSITY
PLASMA
RADIANT HEAT TRANSFER
RED SHIFT
RELATIVISTIC RANGE
SHOCK WAVES
SPACE
TELESCOPES
TEV RANGE