dc.contributor |
Háskóli Íslands (HÍ) |
dc.contributor |
University of Iceland (UI) |
dc.contributor.author |
Ajello, M. |
dc.contributor.author |
Baldini, L. |
dc.contributor.author |
Barbiellini, G. |
dc.contributor.author |
Bastieri, D. |
dc.contributor.author |
Bellazzini, R. |
dc.contributor.author |
Bissaldi, E. |
dc.contributor.author |
Blandford, R. D. |
dc.contributor.author |
Bonino, R. |
dc.contributor.author |
Bottacini, E. |
dc.contributor.author |
Bregeon, J. |
dc.contributor.author |
Bruel, P. |
dc.contributor.author |
Buehler, R. |
dc.contributor.author |
Cameron, R. A. |
dc.contributor.author |
Caputo, R. |
dc.contributor.author |
Caraveo, P. A. |
dc.contributor.author |
Chiaro, G. |
dc.contributor.author |
Ciprini, S. |
dc.contributor.author |
Cohen-Tanugi, J. |
dc.contributor.author |
Costantin, D. |
dc.contributor.author |
D’Ammando, F. |
dc.contributor.author |
de Palma, F. |
dc.contributor.author |
Di Lalla, N. |
dc.contributor.author |
Di Mauro, M. |
dc.contributor.author |
Di Venere, L. |
dc.contributor.author |
Domínguez, A. |
dc.contributor.author |
Favuzzi, C. |
dc.contributor.author |
Franckowiak, A. |
dc.contributor.author |
Fukazawa, Y. |
dc.contributor.author |
Funk, S. |
dc.contributor.author |
Fusco, P. |
dc.contributor.author |
Gargano, F. |
dc.contributor.author |
Gasparrini, D. |
dc.contributor.author |
Giglietto, N. |
dc.contributor.author |
Giordano, F. |
dc.contributor.author |
Giroletti, M. |
dc.contributor.author |
Green, D. |
dc.contributor.author |
Grenier, I. A. |
dc.contributor.author |
Guiriec, S. |
dc.contributor.author |
Holt, C. |
dc.contributor.author |
Horan, D. |
dc.contributor.author |
Jóhannesson, Guðlaugur |
dc.contributor.author |
Kocevski, D. |
dc.contributor.author |
Kuss, M. |
dc.contributor.author |
Mura, G. La |
dc.contributor.author |
Larsson, S. |
dc.contributor.author |
Li, J. |
dc.contributor.author |
Longo, F. |
dc.contributor.author |
Loparco, F. |
dc.contributor.author |
Lubrano, P. |
dc.contributor.author |
Magill, J. D. |
dc.contributor.author |
Maldera, S. |
dc.contributor.author |
Manfreda, A. |
dc.contributor.author |
Mazziotta, M. N. |
dc.contributor.author |
Michelson, P. F. |
dc.contributor.author |
Mizuno, T. |
dc.contributor.author |
Monzani, M. E. |
dc.contributor.author |
Morselli, A. |
dc.contributor.author |
Negro, M. |
dc.contributor.author |
Nuss, E. |
dc.contributor.author |
Omodei, N. |
dc.contributor.author |
Orienti, M. |
dc.contributor.author |
Orlando, E. |
dc.contributor.author |
Paliya, V. S. |
dc.contributor.author |
Perkins, J. S. |
dc.contributor.author |
Persic, M. |
dc.contributor.author |
Pesce-Rollins, M. |
dc.contributor.author |
Piron, F. |
dc.contributor.author |
Principe, G. |
dc.contributor.author |
Racusin, J. L. |
dc.contributor.author |
Rainò, S. |
dc.contributor.author |
Rando, R. |
dc.contributor.author |
Razzano, M. |
dc.contributor.author |
Razzaque, S. |
dc.contributor.author |
Reimer, A. |
dc.contributor.author |
Reimer, O. |
dc.contributor.author |
Sgrò, C. |
dc.contributor.author |
Siskind, E. J. |
dc.contributor.author |
Spandre, G. |
dc.contributor.author |
Spinelli, P. |
dc.contributor.author |
Tak, D. |
dc.contributor.author |
Thayer, J. B. |
dc.contributor.author |
Torres, D. F. |
dc.contributor.author |
Tosti, G. |
dc.contributor.author |
Valverde, J. |
dc.contributor.author |
Vogel, M. |
dc.contributor.author |
Wood, K. |
dc.date.accessioned |
2020-01-24T14:33:08Z |
dc.date.available |
2020-01-24T14:33:08Z |
dc.date.issued |
2018-08-17 |
dc.identifier.citation |
The Fermi Lat Collaboration, 2018. Investigating the Nature of Late-Time High-Energy GRB Emission Through Joint Fermi\Swift Observations. arXiv.org, pp.arXiv.org, Aug 7, 2018. |
dc.identifier.issn |
0004-637X |
dc.identifier.issn |
1538-4357 (eISSN) |
dc.identifier.uri |
https://hdl.handle.net/20.500.11815/1468 |
dc.description |
Publisher's version (útgefin grein). |
dc.description.abstract |
We use joint observations by the Swift X-ray Telescope (XRT) and the Fermi Large Area Telescope (LAT) of
gamma-ray burst (GRB) afterglows to investigate the nature of the long-lived high-energy emission observed by
Fermi LAT. Joint broadband spectral modeling of XRT and LAT data reveals that LAT nondetections of bright
X-ray afterglows are consistent with a cooling break in the inferred electron synchrotron spectrum below the LAT
and/or XRT energy ranges. Such a break is sufficient to suppress the high-energy emission so as to be below the
LAT detection threshold. By contrast, LAT-detected bursts are best fit by a synchrotron spectrum with a cooling
break that lies either between or above the XRT and LAT energy ranges. We speculate that the primary difference
between GRBs with LAT afterglow detections and the nondetected population may be in the type of circumstellar
environment in which these bursts occur, with late-time LAT detections preferentially selecting GRBs that occur in
low wind-like circumburst density profiles. Furthermore, we find no evidence of high-energy emission in the LATdetected population significantly in excess of the flux expected from the electron synchrotron spectrum fit to the
observed X-ray emission. The lack of excess emission at high energies could be due to a shocked external medium
in which the energy density in the magnetic field is stronger than or comparable to that of the relativistic electrons
behind the shock, precluding the production of a dominant synchrotron self-Compton (SSC) component in the
LAT energy range. Alternatively, the peak of the SSC emission could be beyond the 0.1–100 GeV energy range
considered for this analysis. |
dc.description.sponsorship |
Funding text #1
46 Funded by contract FIRB-2012-RBFR12PM1F from the Italian Ministry of Education, University and Research (MIUR). 47 https://fermi.gsfc.nasa.gov/ssc/observations/types/grbs/lat_grbs/
Funding text #2
The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT, as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States; the Commissariat à l’Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France; the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy; the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK), and Japan Aerospace Exploration Agency (JAXA) in Japan; and the K.A.Wallenberg Foundation, the Swedish Research Council, and the Swedish National Space Board in Sweden.
Funding text #3
Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d’Études Spatiales in France. This work performed in part under DOE Contract DE-AC02-76SF00515. |
dc.format.extent |
138 |
dc.language.iso |
en |
dc.publisher |
American Astronomical Society |
dc.relation.ispartofseries |
The Astrophysical Journal;863(2) |
dc.rights |
info:eu-repo/semantics/openAccess |
dc.subject |
Gamma-ray burst |
dc.subject |
Gammageislar |
dc.subject |
Sjónaukar |
dc.title |
Investigating the Nature of Late-time High-energy GRB Emission through Joint Fermi/Swift Observations |
dc.type |
info:eu-repo/semantics/article |
dcterms.license |
Original content from this work may be used under the terms
of the Creative Commons Attribution 3.0 licence. Any further
distribution of this work must maintain attribution to the author(s) and the title
of the work, journal citation and DOI. |
dc.description.version |
Peer Reviewed |
dc.identifier.journal |
Astrophysical Journal |
dc.identifier.doi |
10.3847/1538-4357/aad000 |
dc.contributor.department |
Raunvísindastofnun (HÍ) |
dc.contributor.department |
Science Institute (UI) |
dc.contributor.school |
Verkfræði- og náttúruvísindasvið (HÍ) |
dc.contributor.school |
School of Engineering and Natural Sciences (UI) |