Fermi LAT Stacking Analysis of Swift Localized Gamma-ray Bursts

M. Ackermann; M. Ajello; B. Anderson; W.B. Atwood; M. Axelsson; L. Baldini; G. Barbiellini; D. Bastieri; R. Bellazzini; P.N. Bhat; E. Bissaldi; R. Bonino; E. Bottacini; T.J. Brandt; J. Bregeon; P. Bruel; R. Buehler; S. Buson; G.A. Caliandro; R.A. Cameron; M. Caragiulo; P.A. Caraveo; C. Cecchi; E. Charles; A. Chekhtman; J. Chiang; G. Chiaro; S. Ciprini; R. Claus; Johann Cohen-Tanugi; J. Conrad; S. Cutini; F. d'Ammando; A. de Angelis; F. de Palma; R. Desiante; L. Di Venere; P.S. Drell; C. Favuzzi; W.B. Focke; A. Franckowiak; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Gehrels; N. Giglietto; F. Giordano; M. Giroletti; G. Godfrey; I.A. Grenier; J.E. Grove; S. Guiriec; J.W. Hewitt; A.B. Hill; D. Horan; G. Johannesson; D. Kocevski; C. Kouveliotou; M. Kuss; S. Larsson; J. Li; L. Li; F. Longo; F. Loparco; M.N. Lovellette; P. Lubrano; M. Mayer; M.N. Mazziotta; J.E. Mcenery; P.F. Michelson; T. Mizuno; M.E. Monzani; A. Morselli; S. Murgia; R. Nemmen; E. Nuss; M. Ohno; T. Ohsugi; N. Omodei; M. Orienti; E. Orlando; D. Paneque; J.S. Perkins; M. Pesce-Rollins; F. Piron; G. Pivato; T.A. Porter; J.L. Racusin; S. Raino; R. Rando; M. Razzano; A. Reimer; O. Reimer; M. Schaal; A. Schulz; C. Sgro; E.J. Siskind; F. Spada; G. Spandre; P. Spinelli; H. Takahashi; J.B. Thayer; L. Tibaldo; M. Tinivella; D.F. Torres; G. Tosti; E. Troja; G. Vianello; A. von Kienlin; M. Werner; K.S. Wood

doi:10.3847/0004-637X/822/2/68

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Fermi LAT Stacking Analysis of Swift Localized Gamma-ray Bursts

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Fermi LAT Stacking Analysis of Swift Localized Gamma-ray Bursts

M. Ackermann, M. Ajello, B. Anderson, W.B. Atwood, M. Axelsson, L. Baldini, G. Barbiellini, D. Bastieri, R. Bellazzini, P.N. Bhat, …

The Astrophysical Journal, Vol.822

2016

DOI: https://doi.org/10.3847/0004-637X/822/2/68

Abstract

We perform a comprehensive stacking analysis of data collected by the Fermi Large Area Telescope (LAT) of gamma-ray bursts (GRB) localized by the Swift spacecraft, which were not detected by the LAT but which fell within the instrument's field of view at the time of trigger. We examine a total of 79 GRBs by comparing the observed counts over a range of time intervals to that expected from designated background orbits, as well as by using a joint likelihood technique to model the expected distribution of stacked counts. We find strong evidence for subthreshold emission at MeV to GeV energies using both techniques. This observed excess is detected during intervals that include and exceed the durations typically characterizing the prompt emission observed at keV energies and lasts at least 2700 s after the co-aligned burst trigger. By utilizing a novel cumulative likelihood analysis, we find that although a burst's prompt gamma-ray and afterglow X-ray flux both correlate with the strength of the subthreshold emission, the X-ray afterglow flux measured by Swift's X-ray Telescope (XRT) at 11 hr post trigger correlates far more significantly. Overall, the extended nature of the subthreshold emission and its connection to the burst's afterglow brightness lend further support to the external forward shock origin of the late-time emission detected by the LAT. These results suggest that the extended high-energy emission observed by the LAT may be a relatively common feature but remains undetected in a majority of bursts owing to instrumental threshold effects.

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Title: Fermi LAT Stacking Analysis of Swift Localized Gamma-ray Bursts
Creators - without role: M. Ackermann - Deutsches Elektronen-Synchrotron DESY
M. Ajello - Clemson University
B. Anderson
W.B. Atwood - University of California, Santa Cruz
M. Axelsson - AlbaNova
L. Baldini - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
G. Barbiellini - University of Trieste
D. Bastieri - INFN Sezione di Padova
R. Bellazzini - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
P.N. Bhat - University of Alabama in Huntsville
E. Bissaldi - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
R. Bonino - University of Turin
E. Bottacini - Kavli Institute for Particle Astrophysics and Cosmology
T.J. Brandt - Goddard Space Flight Center
J. Bregeon - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
P. Bruel - Laboratoire Leprince-Ringuet
R. Buehler - Deutsches Elektronen-Synchrotron DESY
S. Buson - Istituto Nazionale di Fisica Nucleare, Sezione di Padova
G.A. Caliandro - Kavli Institute for Particle Astrophysics and Cosmology
R.A. Cameron - Stanford University
M. Caragiulo - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
P.A. Caraveo - Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano
C. Cecchi - University of Perugia
E. Charles - Kavli Institute for Particle Astrophysics and Cosmology
A. Chekhtman - George Mason University
J. Chiang - Kavli Institute for Particle Astrophysics and Cosmology
G. Chiaro - University of Padua
S. Ciprini - Agenzia Spaziale Italiana
R. Claus - Kavli Institute for Particle Astrophysics and Cosmology
Johann Cohen-Tanugi - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
J. Conrad - Fraunhofer Chalmers Research Centre for Industrial Mathematics
S. Cutini - Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
F. d'Ammando
A. de Angelis - Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
F. de Palma - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
R. Desiante - University of Udine
L. Di Venere - Polytechnic University of Bari
P.S. Drell - Kavli Institute for Particle Astrophysics and Cosmology
C. Favuzzi - Polytechnic University of Bari
W.B. Focke - SLAC National Accelerator Laboratory
A. Franckowiak - Stanford University
S. Funk - Universitätsklinikum Erlangen
P. Fusco - Polytechnic University of Bari
F. Gargano - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
D. Gasparrini - Agenzia Spaziale Italiana
N. Gehrels - Goddard Space Flight Center
N. Giglietto - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
F. Giordano - Polytechnic University of Bari
M. Giroletti - Istituto di Radioastronomia di Bologna
G. Godfrey - Kavli Institute for Particle Astrophysics and Cosmology
I.A. Grenier - CEA Paris-Saclay
J.E. Grove - United States Naval Research Laboratory
S. Guiriec - Goddard Space Flight Center
J.W. Hewitt - University of Maryland, Baltimore County
A.B. Hill - University of Southampton
D. Horan - Laboratoire Leprince-Ringuet
G. Johannesson - University of Iceland
D. Kocevski - Goddard Space Flight Center
C. Kouveliotou - George Washington University
M. Kuss - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
S. Larsson - Stockholm University
J. Li - Institute of Space Sciences
L. Li - KTH Royal Institute of Technology
F. Longo - Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
F. Loparco - Polytechnic University of Bari
M.N. Lovellette - United States Naval Research Laboratory
P. Lubrano - University of Perugia
M. Mayer - Deutsches Elektronen-Synchrotron DESY
M.N. Mazziotta - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
J.E. Mcenery - University of Maryland, College Park
P.F. Michelson - Kavli Institute for Particle Astrophysics and Cosmology
T. Mizuno - Hiroshima University
M.E. Monzani - Kavli Institute for Particle Astrophysics and Cosmology
A. Morselli - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
S. Murgia - University of California, Irvine
R. Nemmen - Universidade de São Paulo
E. Nuss - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
M. Ohno - Hiroshima University
T. Ohsugi - Hiroshima University
N. Omodei - Kavli Institute for Particle Astrophysics and Cosmology
M. Orienti - Istituto di Radioastronomia di Bologna
E. Orlando - SLAC National Accelerator Laboratory
D. Paneque - Max Planck Institute for Physics
J.S. Perkins - Goddard Space Flight Center
M. Pesce-Rollins - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
F. Piron - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
G. Pivato - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
T.A. Porter - Kavli Institute for Particle Astrophysics and Cosmology
J.L. Racusin - Goddard Space Flight Center
S. Raino - Polytechnic University of Bari
R. Rando - Istituto Nazionale di Fisica Nucleare, Sezione di Padova
M. Razzano - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
A. Reimer - Stanford University
O. Reimer - Kavli Institute for Particle Astrophysics and Cosmology
M. Schaal - National Academies of Sciences, Engineering, and Medicine
A. Schulz - Deutsches Elektronen-Synchrotron DESY
C. Sgro - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
E.J. Siskind - Real Time Tomography
F. Spada - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
G. Spandre - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
P. Spinelli - Polytechnic University of Bari
H. Takahashi - Hiroshima University
J.B. Thayer - Stanford University
L. Tibaldo - SLAC National Accelerator Laboratory
M. Tinivella - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
D.F. Torres - Institució Catalana de Recerca i Estudis Avançats
G. Tosti - Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
E. Troja - University of Maryland, College Park
G. Vianello - Kavli Institute for Particle Astrophysics and Cosmology
A. von Kienlin - Max Planck Institute for Extraterrestrial Physics
M. Werner - Universität Innsbruck
K.S. Wood - United States Naval Research Laboratory
Publication Details: The Astrophysical Journal, Vol.822
Identifiers: 9942419909311
Academic Unit: Laboratoire Univers et Particules de Montpellier - LUPM
Language: English
Resource Type: Journal article
Local Fields: hal-02017416