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Title: Blue supergiant model for ultra-long gamma-ray burst with superluminous-supernova-like bump

Long gamma-ray bursts (LGRBs) have a typical duration of ∼30 s, and some of them are associated with hypernovae, such as Type Ic SN 1998bw. Wolf-Rayet stars are the most plausible LGRB progenitors, since the free fall time of the envelope is consistent with the duration, and the natural outcome of the progenitor is a Type Ic SN. While a new population of ultra-long GRBs (ULGRBs), GRB 111209A, GRB 101225A, and GRB 121027A, has a duration of ∼10{sup 4} s, two of them are accompanied by superluminous-supernova-like (SLSN-like) bumps, which are ≲ 10 times brighter than typical hypernovae. Wolf-Rayet progenitors cannot explain ULGRBs because of durations that are too long and SN-like bumps that are too bright. A blue supergiant (BSG) progenitor model, however, can explain the duration of ULGRBs. Moreover, SLSN-like bumps can be attributed to the so-called cocoon fireball photospheric emissions (CFPEs). Since a large cocoon is inevitably produced during the relativistic jet piercing though the BSG envelope, this component can be smoking gun evidence of the BSG model for ULGRBs. In this paper, we examine u-, g-, r-, i-, and J-band light curves of three ULGRBs and demonstrate that they can be fitted quite well by ourmore » BSG model with the appropriate choices of the jet opening angle and the number density of the ambient gas. In addition, we predict that for 121027A, SLSN-like bump could have been observed for ∼20-80 days after the burst. We also propose that some SLSNe might be CFPEs of off-axis ULGRBs without visible prompt emissions.« less
Authors:
;  [1] ;  [2] ;  [3]
  1. Department of Physics, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan)
  2. Department of Astronomy and Astrophysics, Department of Physics, Center for Particle and Gravitational Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)
  3. Yukawa Institute for Theoretical Physics, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan)
Publication Date:
OSTI Identifier:
22341989
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 778; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMIC GAMMA BURSTS; DENSITY; DIAGRAMS; EMISSION; NUCLEAR FIREBALLS; RELATIVISTIC RANGE; VISIBLE RADIATION; WOLF-RAYET STARS