FERMI LARGE AREA TELESCOPE OBSERVATION OF A GAMMA-RAY SOURCE AT THE POSITION OF ETA CARINAE

Journal Article · Mon Nov 01 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/723/1/649· OSTI ID:21467169

Abdo, A A ^[1]; Ackermann, M; Ajello, M; Allafort, A; Bechtol, K; Berenji, B; Blandford, R D; Borgland, A W; Bouvier, A ^[2]; Baldini, L; Bellazzini, R; Bregeon, J; Brez, A ^[3]; Ballet, J ^[4]; Barbiellini, G ^[5]; Bastieri, D ^[6]; Bonamente, E ^[7]; Brandt, T J ^[8]; Brigida, M ^[9]; Bruel, P ^[10]

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1. Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)
2. W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)
3. Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy)
4. Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France)
5. Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy)
6. Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy)
7. Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy)
8. Centre d'Etude Spatiale des Rayonnements, CNRS/UPS, BP 44346, F-30128 Toulouse Cedex 4 (France)
9. Dipartimento di Fisica 'M. Merlin' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy)
10. Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France)

The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope detected a {gamma}-ray source that is spatially consistent with the location of Eta Carinae. This source has been persistently bright since the beginning of the LAT survey observations (from 2008 August to 2009 July, the time interval considered here). The {gamma}-ray signal is detected significantly throughout the LAT energy band (i.e., up to {approx}100 GeV). The 0.1-100 GeV energy spectrum is well represented by a combination of a cutoff power-law model (<10 GeV) and a hard power-law component (>10 GeV). The total flux (>100 MeV) is 3.7{sup +0.3}{sub -0.1} x 10{sup -7} photons s{sup -1} cm{sup -2}, with additional systematic uncertainties of 10%, and consistent with the average flux measured by AGILE. The light curve obtained by Fermi is consistent with steady emission. Our observations do not confirm the presence of a {gamma}-ray flare in 2008 October, as reported by Tavani et al., although we cannot exclude that a flare lasting only a few hours escaped detection by the Fermi LAT. We also do not find any evidence for {gamma}-ray variability that correlates with the large X-ray variability of Eta Carinae observed during 2008 December and 2009 January. We are thus not able to establish an unambiguous identification of the LAT source with Eta Carinae.

• OSTI ID: 21467169
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 723; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BOSONS
COSMIC GAMMA SOURCES
COSMIC RAY SOURCES
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ENERGY RANGE
ENERGY SPECTRA
GAMMA RADIATION
GEV RANGE
GEV RANGE 10-100
IONIZING RADIATIONS
MASSLESS PARTICLES
MEV RANGE
MEV RANGE 100-1000
PHOTONS
RADIATIONS
SPECTRA
STARS
TELESCOPES