The afterglow of GRB 130427A from 1 to 10{sup 16} GHz
- Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Blvd, Pasadena, CA 91125 (United States)
- Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States)
- Physics Department, George Washington University, 725 21st St, NW Washington, DC 20052 (United States)
- Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom)
- Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)
- Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, D-85748 Garching (Germany)
- Department of Physics, University of Adiyaman, 02040 Adiyaman (Turkey)
- Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)
- Yunnan Observatories, Chinese Academy of Sciences, P.O. Box 110, 650011 Kunming (China)
- Institute de Radioastronomie Millimètrique (IRAM), 300 rue de la Piscine, F-38406 Saint Martin d'Hères (France)
- Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, E-18008 Granada (Spain)
- National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States)
- Space Telescope Science Institute, Baltimore, MD 21218 (United States)
- Sabancı University, Orhanlı- Tuzla, İstanbul 34956 (Turkey)
We present multiwavelength observations of the afterglow of GRB 130427A, the brightest (in total fluence) gamma-ray burst (GRB) of the past 29 yr. Optical spectroscopy from Gemini-North reveals the redshift of the GRB to be z = 0.340, indicating that its unprecedented brightness is primarily the result of its relatively close proximity to Earth; the intrinsic luminosities of both the GRB and its afterglow are not extreme in comparison to other bright GRBs. We present a large suite of multiwavelength observations spanning from 300 s to 130 days after the burst and demonstrate that the afterglow shows relatively simple, smooth evolution at all frequencies, with no significant late-time flaring or rebrightening activity. The entire data set from 1 GHz to 10 GeV can be modeled as synchrotron emission from a combination of reverse and forward shocks in good agreement with the standard afterglow model, providing strong support to the applicability of the underlying theory and clarifying the nature of the GeV emission observed to last for minutes to hours following other very bright GRBs. A tenuous, wind-stratified circumburst density profile is required by the observations, suggesting a massive-star progenitor with a low mass-loss rate, perhaps due to low metallicity. GRBs similar in nature to GRB 130427A, inhabiting low-density media and exhibiting strong reverse shocks, are probably not uncommon but may have been difficult to recognize in the past owing to their relatively faint late-time radio emission; more such events should be found in abundance by the new generation of sensitive radio and millimeter instruments.
- OSTI ID:
- 22348160
- Journal Information:
- Astrophysical Journal, Vol. 781, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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