Fermi LAT Observations of LS I +61 303: First detection of an orbital modulation in GeV Gamma Rays

A. A. Abdo; M. Ackermann; M. Ajello; W. B. Atwood; M. Axelsson; L. Baldini; Jean Ballet; G. Barbiellini; D. Bastieri; B. M. Baughman; K. Bechtol; R. Bellazzini; B. Berenji; R. Blandford; E. D. Bloom; E. Bonamente; A. W. Borgland; J. Bregeon; A. Brez; M. Brigida; Pascal Bruel; T. H. Burnett; G. A. Caliandro; R. A. Cameron; P. A. Caraveo; J. M. Casandjian; E. Cavazzuti; C. Cecchi; Ö. Çelik; E. Charles; S. Chaty; A. Chekhtman; C. C. Cheung; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; L. R. Cominsky; J. Conrad; S. Corbel; R. Corbet; S. Cutini; C. D. Dermer; A. de Angelis; A. de Luca; F. de Palma; S. W. Digel; M. Dormody; E. Do Couto e Silva; P. S. Drell; R. Dubois; G. Dubus; D. Dumora; C. Farnier; C. Favuzzi; S. J. Fegan; W. B. Focke; M. Frailis; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Gehrels; S. Germani; B. Giebels; N. Giglietto; F. Giordano; T. Glanzman; G. Godfrey; I. A. Grenier; M.-H. Grondin; J. E. Grove; L. Guillemot; S. Guiriec; Y. Hanabata; A. K. Harding; M. Hayashida; E. Hays; A. B. Hill; R. E. Hughes; G. Jóhannesson; A. S. Johnson; R. P. Johnson; T. J. Johnson; W. N. Johnson; T. Kamae; H. Katagiri; J. Kataoka; N. Kawai; M. Kerr; Jürgen Knödlseder; M. L. Kocian; F. Kuehn; M. Kuss; J. Lande; S. Larsson; L. Latronico; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; G. M. Madejski; A. Makeev; M. Marelli; M. N. Mazziotta; J. E. Mcenery; C. Meurer; P. F. Michelson; W. Mitthumsiri; T. Mizuno; C. Monte; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; P. L. Nolan; E. Nuss; T. Ohsugi; A. Okumura; N. Omodei; E. Orlando; J. F. Ormes; D. Paneque; J. H. Panetta; D. Parent; V. Pelassa; M. Pepe; M. Pesce-Rollins; F. Piron; T. A. Porter; S. Rainò; R. Rando; P. S. Ray; M. Razzano; N. Rea; A. Reimer; O. Reimer; T. Reposeur; S. Ritz; L. S. Rochester; A. Y. Rodriguez; R. W. Romani; F. Ryde; H. F.-W. Sadrozinski; D. Sanchez; A. Sander; P. M. Saz Parkinson; J. D. Scargle; C. Sgrò; M. S. Shaw; A. Sierpowska-Bartosik; E. J. Siskind; David Stanley Smith; P. D. Smith; G. Spandre; P. Spinelli; E. Striani; M. S. Strickman; D. J. Suson; H. Tajima; H. Takahashi; T. Takahashi; T. Tanaka; J. B. Thayer; J. G. Thayer; D. J. Thompson; L. Tibaldo; D. F. Torres; G. Tosti; A. Tramacere; Y. Uchiyama; T. L. Usher; V. Vasileiou; N. Vilchez; V. Vitale; A. P. Waite; P. Wang; B. L. Winer; K. S. Wood; T. Ylinen; M. Ziegler

doi:10.1088/0004-637X/701/2/L123

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Fermi LAT Observations of LS I +61 303: First detection of an orbital modulation in GeV Gamma Rays

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Fermi LAT Observations of LS I +61 303: First detection of an orbital modulation in GeV Gamma Rays

A. A. Abdo, M. Ackermann, M. Ajello, W. B. Atwood, M. Axelsson, L. Baldini, Jean Ballet, G. Barbiellini, D. Bastieri, B. M. Baughman, …

The Astrophysical Journal Letters, Vol.701, pp.123-128

10/08/2009

DOI: https://doi.org/10.1088/0004-637X/701/2/L123

Abstract

binaries: close

gamma rays: observations

stars: variables: other

X-rays: binaries

X-rays: individual (LS I +61° 303)

This Letter presents the first results from the observations of LS I +61°303 using Large Area Telescope data from the Fermi Gamma-Ray Space Telescope between 2008 August and 2009 March. Our results indicate variability that is consistent with the binary period, with the emission being modulated at 26.6 ± 0.5 days. This constitutes the first detection of orbital periodicity in high-energy gamma rays (20 MeV-100 GeV, HE). The light curve is characterized by a broad peak after periastron, as well as a smaller peak just before apastron. The spectrum is best represented by a power law with an exponential cutoff, yielding an overall flux above 100 MeV of 0.82 ± 0.03(stat) ± 0.07(syst) 10–6 ph cm–2 s–1, with a cutoff at 6.3 ± 1.1(stat) ± 0.4(syst) GeV and photon index Γ = 2.21 ± 0.04(stat) ± 0.06(syst). There is no significant spectral change with orbital phase. The phase of maximum emission, close to periastron, hints at inverse Compton scattering as the main radiation mechanism. However, previous very high-energy gamma ray (>100 GeV, VHE) observations by MAGIC and VERITAS show peak emission close to apastron. This and the energy cutoff seen with Fermi suggest that the link between HE and VHE gamma rays is nontrivial.

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Title: Fermi LAT Observations of LS I +61 303: First detection of an orbital modulation in GeV Gamma Rays
Creators - without role: A. A. Abdo - United States Naval Research Laboratory
M. Ackermann - Kavli Institute for Particle Astrophysics and Cosmology
M. Ajello - Kavli Institute for Particle Astrophysics and Cosmology
W. B. Atwood - University of California, Santa Cruz
M. Axelsson - AlbaNova
L. Baldini - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
Jean Ballet - Astrophysique, Instrumentation et Modélisation
G. Barbiellini - University of Trieste
D. Bastieri - University of Padua
B. M. Baughman - The Ohio State University
K. Bechtol - Kavli Institute for Particle Astrophysics and Cosmology
R. Bellazzini - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
B. Berenji - Kavli Institute for Particle Astrophysics and Cosmology
R. Blandford - Kavli Institute for Particle Astrophysics and Cosmology
E. D. Bloom - Kavli Institute for Particle Astrophysics and Cosmology
E. Bonamente - University of Perugia
A. W. Borgland - Stanford University
J. Bregeon - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
A. Brez - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
M. Brigida - Polytechnic University of Bari
Pascal Bruel - École Polytechnique
T. H. Burnett - University of Washington
G. A. Caliandro - Polytechnic University of Bari
R. A. Cameron - Stanford University
P. A. Caraveo - Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano
J. M. Casandjian - Université Paris Cité
E. Cavazzuti - Agenzia Spaziale Italiana
C. Cecchi - University of Perugia
Ö. Çelik - Goddard Space Flight Center
E. Charles - Kavli Institute for Particle Astrophysics and Cosmology
S. Chaty - Institut de Recherche sur les Lois Fondamentales de l'Univers
A. Chekhtman - George Mason University
C. C. Cheung - Goddard Space Flight Center
J. Chiang - Kavli Institute for Particle Astrophysics and Cosmology
S. Ciprini - University of Perugia
R. Claus - Kavli Institute for Particle Astrophysics and Cosmology
J. Cohen-Tanugi - Institut National de Physique Nucléaire et de Physique des Particules
L. R. Cominsky - Sonoma State University
J. Conrad - Stockholm University
S. Corbel - Institut de Recherche sur les Lois Fondamentales de l'Univers
R. Corbet - University of Maryland, Baltimore County
S. Cutini - Agenzia Spaziale Italiana
C. D. Dermer - United States Naval Research Laboratory
A. de Angelis - Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
A. de Luca - Istituto Universitario di Studi Superiori di Pavia
F. de Palma - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
S. W. Digel - Kavli Institute for Particle Astrophysics and Cosmology
M. Dormody - University of California, Santa Cruz
E. Do Couto e Silva
P. S. Drell - Kavli Institute for Particle Astrophysics and Cosmology
R. Dubois - Stanford University
G. Dubus - Université Joseph Fourier
D. Dumora - Laboratoire de Physique des deux infinis Bordeaux
C. Farnier - Laboratoire de Physique Théorique
C. Favuzzi - Polytechnic University of Bari
S. J. Fegan - Laboratoire Leprince-Ringuet
W. B. Focke - SLAC National Accelerator Laboratory
M. Frailis - Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
Y. Fukazawa - Hiroshima University
S. Funk - Stanford University
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
S. Germani - University of Perugia
B. Giebels - Laboratoire Leprince-Ringuet
N. Giglietto - Polytechnic University of Bari
F. Giordano - Polytechnic University of Bari
T. Glanzman - Stanford University
G. Godfrey - Kavli Institute for Particle Astrophysics and Cosmology
I. A. Grenier - CEA Paris-Saclay
M.-H. Grondin - Laboratoire de Physique des deux infinis Bordeaux
J. E. Grove - United States Naval Research Laboratory
L. Guillemot - Laboratoire de Physique des deux infinis Bordeaux
S. Guiriec - University of Alabama in Huntsville
Y. Hanabata - Hiroshima University
A. K. Harding - Goddard Space Flight Center
M. Hayashida - Stanford University
E. Hays - Goddard Space Flight Center
A. B. Hill - Université Joseph Fourier
R. E. Hughes - The Ohio State University
G. Jóhannesson - Stanford University
A. S. Johnson - SLAC National Accelerator Laboratory
R. P. Johnson - University of California, Santa Cruz
T. J. Johnson - University of Maryland, College Park
W. N. Johnson - United States Naval Research Laboratory
T. Kamae - SLAC National Accelerator Laboratory
H. Katagiri - Hiroshima University
J. Kataoka - Waseda University
N. Kawai - RIKEN
M. Kerr - University of Washington
Jürgen Knödlseder - Université Toulouse III - Paul Sabatier
M. L. Kocian - Kavli Institute for Particle Astrophysics and Cosmology
F. Kuehn - The Ohio State University
M. Kuss - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
J. Lande - Kavli Institute for Particle Astrophysics and Cosmology
S. Larsson - Stockholm University
L. Latronico - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
F. Longo - University of Trieste
F. Loparco - Polytechnic University of Bari
B. Lott - Laboratoire de Physique des deux infinis Bordeaux
M. N. Lovellette - United States Naval Research Laboratory
P. Lubrano - University of Perugia
G. M. Madejski - Kavli Institute for Particle Astrophysics and Cosmology
A. Makeev - United States Naval Research Laboratory
M. Marelli - Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano
M. N. Mazziotta - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
J. E. Mcenery - Goddard Space Flight Center
C. Meurer - AlbaNova
P. F. Michelson - Kavli Institute for Particle Astrophysics and Cosmology
W. Mitthumsiri - Stanford University
T. Mizuno - Hiroshima University
C. Monte - Polytechnic University of Bari
M. E. Monzani - Kavli Institute for Particle Astrophysics and Cosmology
A. Morselli - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
I. V. Moskalenko - Stanford University
S. Murgia - SLAC National Accelerator Laboratory
P. L. Nolan - Kavli Institute for Particle Astrophysics and Cosmology
E. Nuss - Laboratoire de Physique Théorique
T. Ohsugi - Hiroshima University
A. Okumura - The University of Tokyo
N. Omodei - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
E. Orlando - Max Planck Institute for Extraterrestrial Physics
J. F. Ormes - University of Denver
D. Paneque - Stanford University
J. H. Panetta - Stanford University
D. Parent - Institut National de Physique Nucléaire et de Physique des Particules
V. Pelassa - Laboratoire de Physique Théorique
M. Pepe - University of Perugia
M. Pesce-Rollins - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
F. Piron - Institut National de Physique Nucléaire et de Physique des Particules
T. A. Porter - University of California, Santa Cruz
S. Rainò - Polytechnic University of Bari
R. Rando - University of Padua
P. S. Ray - United States Naval Research Laboratory
M. Razzano - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
N. Rea - Institute of Space Sciences
A. Reimer - Kavli Institute for Particle Astrophysics and Cosmology
O. Reimer - Kavli Institute for Particle Astrophysics and Cosmology
T. Reposeur - Laboratoire de Physique des deux infinis Bordeaux
S. Ritz - Goddard Space Flight Center
L. S. Rochester - Kavli Institute for Particle Astrophysics and Cosmology
A. Y. Rodriguez - Institute of Space Sciences
R. W. Romani - Kavli Institute for Particle Astrophysics and Cosmology
F. Ryde - KTH Royal Institute of Technology
H. F.-W. Sadrozinski - University of California, Santa Cruz
D. Sanchez - Laboratoire Leprince-Ringuet
A. Sander - The Ohio State University
P. M. Saz Parkinson
J. D. Scargle - Ames Research Center
C. Sgrò - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
M. S. Shaw - Kavli Institute for Particle Astrophysics and Cosmology
A. Sierpowska-Bartosik - Institute of Space Sciences
E. J. Siskind - Real Time Tomography
David Stanley Smith - Laboratoire de Physique des deux infinis Bordeaux
P. D. Smith - The Ohio State University
G. Spandre - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
P. Spinelli - Polytechnic University of Bari
E. Striani - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
M. S. Strickman - United States Naval Research Laboratory
D. J. Suson - Purdue University Northwest
H. Tajima - Stanford University
H. Takahashi - Hiroshima University
T. Takahashi - Institute of Space and Astronautical Science
T. Tanaka - Stanford University
J. B. Thayer - Stanford University
J. G. Thayer - SLAC National Accelerator Laboratory
D. J. Thompson - Goddard Space Flight Center
L. Tibaldo - Istituto Nazionale di Fisica Nucleare, Sezione di Padova
D. F. Torres - Institute of Space Sciences
G. Tosti - Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
A. Tramacere - Kavli Institute for Particle Astrophysics and Cosmology
Y. Uchiyama - Kavli Institute for Particle Astrophysics and Cosmology
T. L. Usher - Kavli Institute for Particle Astrophysics and Cosmology
V. Vasileiou - University of Maryland, Baltimore County
N. Vilchez - Université Toulouse III - Paul Sabatier
V. Vitale - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
A. P. Waite - Kavli Institute for Particle Astrophysics and Cosmology
P. Wang - SLAC National Accelerator Laboratory
B. L. Winer - The Ohio State University
K. S. Wood - United States Naval Research Laboratory
T. Ylinen - AlbaNova
M. Ziegler - University of California, Santa Cruz
Publication Details: The Astrophysical Journal Letters, Vol.701, pp.123-128
Identifiers: 9941327209311
Academic Unit: Université de Montpellier
Language: English
Resource Type: Journal article
Local Fields: in2p3-00410616