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dc.contributor.authorMirabal, N.
dc.contributor.authorHalpern, J. P.
dc.contributor.authorChornock, Ryan
dc.contributor.authorFilippenko, Alexei V.
dc.contributor.authorTerndrup, D. M.
dc.contributor.authorArmstrong, E.
dc.contributor.authorKemp, J.
dc.contributor.authorThorstensen, J. R.
dc.contributor.authorTavarez, M.
dc.contributor.authorEspaillat, C.
dc.date.accessioned2020-09-09T15:47:39Z
dc.date.available2020-09-09T15:47:39Z
dc.date.issued2003-06-06
dc.description.abstractThe rapid localization of GRB 021004 by the HETE-2 satellite allowed nearly continuous monitoring of its early optical afterglow decay, as well as high-quality optical spectra that determined a redshift of z3 = 2.328 for its host galaxy, an active starburst galaxy with strong Lyα emission and several absorption lines. Spectral observations show multiple absorbers at z3A = 2.323, z3B = 2.317, and z3C = 2.293 blueshifted by ~450, ~990, and ~3155 km s⁻¹, respectively, relative to the host galaxy Lyα emission. We argue that these correspond to a fragmented shell nebula that has been radiatively accelerated by the gamma-ray burst (GRB) afterglow at a distance gsim0.3 pc from a Wolf-Rayet star GRB progenitor. The chemical abundance ratios indicate that the nebula is overabundant in carbon and silicon. The high level of carbon and silicon is consistent with a swept-up shell nebula gradually enriched by a carbon-rich late-type Wolf-Rayet progenitor wind over the lifetime of the nebula prior to the GRB onset. The detection of statistically significant fluctuations and color changes about the jetlike optical decay further supports this interpretation, since fluctuations must be present at some level as a result of irregularities in a clumpy stellar wind medium or if the progenitor has undergone massive ejection prior to the GRB onset. This evidence suggests that the mass-loss process in a Wolf-Rayet star might lead naturally to an iron core collapse with sufficient angular momentum that could serve as a suitable GRB progenitor. Even though we cannot rule out definitely the alternatives of a dormant QSO, large-scale superwinds, or a several hundred year old supernova remnant responsible for the blueshifted absorbers, these findings point to the likelihood of a signature for a massive-star GRB progenitor.en_US
dc.description.sponsorshipWe would like to thank Sebastiano Novati and Vincenzo Cardone for obtaining observations at the MDM Observatory, and the Keck Observatory staff for their assistance. We thank Jim Applegate, Orsola De Marco, and Mordecai-Mark Mac Low for useful conversations. We also acknowledge Eric Gotthelf for allowing us to use his Alpha computer. This material is based upon work supported by the National Science Foundation under Grants AST-0206051 to J. P. H. and AST-9987438 to A. V. F.en_US
dc.description.urihttps://iopscience.iop.org/article/10.1086/377471en_US
dc.format.extent40 pagesen_US
dc.genrejournal articles preprintsen_US
dc.identifierdoi:10.13016/m2ci2h-dnjz
dc.identifier.citationN. Mirabal et al., GRB 021004: A Possible Shell Nebula around a Wolf-Rayet Star Gamma-Ray Burst Progenitor, ApJ 595 935 (2003), doi: https://doi.org/10.1086/377471en_US
dc.identifier.urihttps://doi.org/10.1086/377471
dc.identifier.urihttp://hdl.handle.net/11603/19613
dc.language.isoen_USen_US
dc.publisherIOPen_US
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC Physics Department Collection
dc.relation.ispartofUMBC Joint Center for Earth Systems Technology (JCET)
dc.relation.ispartofUMBC Center for Space Sciences and Technology (CSST) / Center for Research and Exploration in Space Sciences & Technology II (CRSST II)
dc.rightsThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
dc.rights© 2003. The American Astronomical Society. All rights reserved.
dc.titleGRB 021004: A Possible Shell Nebula around a Wolf-Rayet Star Gamma-Ray Burst Progenitoren_US
dc.typeTexten_US


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