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Title: Fermi Large Area Telescope Observation Of A Gamma-Ray Source At The Position Of Eta Carinae

Abstract

The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope detected a γ-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 γ-ray signal is detected significantly throughout the LAT energy band (i.e., up to ~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 +0.3 –0.1 × 10 –7 photons s –1 cm –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 γ-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 γ-ray variability that correlates with the large X-ray variability of Eta Carinae observed during 2008 December and 2009 January.more » We are thus not able to establish an unambiguous identification of the LAT source with Eta Carinae.« less

Authors:
 [1]
  1. Naval Research Lab. (NRL), Washington, DC (United States); et al.
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
Contributing Org.:
Fermi LAT Collaboration
OSTI Identifier:
1357519
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Accepted Manuscript
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 723; Journal Issue: 1; Journal ID: ISSN 0004-637X
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS

Citation Formats

Abdo, A. A,. Fermi Large Area Telescope Observation Of A Gamma-Ray Source At The Position Of Eta Carinae. United States: N. p., 2010. Web. doi:10.1088/0004-637X/723/1/649.
Abdo, A. A,. Fermi Large Area Telescope Observation Of A Gamma-Ray Source At The Position Of Eta Carinae. United States. doi:10.1088/0004-637X/723/1/649.
Abdo, A. A,. Wed . "Fermi Large Area Telescope Observation Of A Gamma-Ray Source At The Position Of Eta Carinae". United States. doi:10.1088/0004-637X/723/1/649. https://www.osti.gov/servlets/purl/1357519.
@article{osti_1357519,
title = {Fermi Large Area Telescope Observation Of A Gamma-Ray Source At The Position Of Eta Carinae},
author = {Abdo, A. A,},
abstractNote = {The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope detected a γ-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 γ-ray signal is detected significantly throughout the LAT energy band (i.e., up to ~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+0.3 –0.1 × 10–7 photons s–1 cm–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 γ-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 γ-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.},
doi = {10.1088/0004-637X/723/1/649},
journal = {Astrophysical Journal},
number = 1,
volume = 723,
place = {United States},
year = {2010},
month = {10}
}

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