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Title: Fermi-LAT upper limits on gamma-ray emission from colliding wind binaries

Here, colliding wind binaries (CWBs) are thought to give rise to a plethora of physical processes including acceleration and interaction of relativistic particles. Observation of synchrotron radiation in the radio band confirms there is a relativistic electron population in CWBs. Accordingly, CWBs have been suspected sources of high-energy γ-ray emission since the COS-B era. Theoretical models exist that characterize the underlying physical processes leading to particle acceleration and quantitatively predict the non-thermal energy emission observable at Earth. Furthermore, we strive to find evidence of γ-ray emission from a sample of seven CWB systems: WR 11, WR 70, WR 125, WR 137, WR 140, WR 146, and WR 147. Theoretical modelling identified these systems as the most favourable candidates for emitting γ-rays. We make a comparison with existing γ-ray flux predictions and investigate possible constraints. We used 24 months of data from the Large Area Telescope (LAT) on-board the Fermi Gamma Ray Space Telescope to perform a dedicated likelihood analysis of CWBs in the LAT energy range. As a result, we find no evidence of γ-ray emission from any of the studied CWB systems and determine corresponding flux upper limits. For some CWBs the interplay of orbital and stellar parameters rendersmore » the Fermi-LAT data not sensitive enough to constrain the parameter space of the emission models. In the cases of WR140 and WR147, the Fermi -LAT upper limits appear to rule out some model predictions entirely and constrain theoretical models over a significant parameter space. A comparison of our findings to the CWB η Car is made.« less
Authors:
 [1] ;  [2] ;  [2] ;  [1]
  1. Leopold-Franzens-Univ. Innsbruck, Innsbruck (Austria)
  2. Leopold-Franzens-Univ. Innsbruck, Innsbruck (Austria); Stanford Univ., StanfordCA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Astronomy and Astrophysics
Additional Journal Information:
Journal Volume: 555; Journal ID: ISSN 0004-6361
Publisher:
EDP Sciences
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; gamma rays: stars; stars: massive; binaries: general
OSTI Identifier:
1356573

Werner, Michael, Reimer, O., Reimer, A., and Egberts, K.. Fermi-LAT upper limits on gamma-ray emission from colliding wind binaries. United States: N. p., Web. doi:10.1051/0004-6361/201220502.
Werner, Michael, Reimer, O., Reimer, A., & Egberts, K.. Fermi-LAT upper limits on gamma-ray emission from colliding wind binaries. United States. doi:10.1051/0004-6361/201220502.
Werner, Michael, Reimer, O., Reimer, A., and Egberts, K.. 2013. "Fermi-LAT upper limits on gamma-ray emission from colliding wind binaries". United States. doi:10.1051/0004-6361/201220502. https://www.osti.gov/servlets/purl/1356573.
@article{osti_1356573,
title = {Fermi-LAT upper limits on gamma-ray emission from colliding wind binaries},
author = {Werner, Michael and Reimer, O. and Reimer, A. and Egberts, K.},
abstractNote = {Here, colliding wind binaries (CWBs) are thought to give rise to a plethora of physical processes including acceleration and interaction of relativistic particles. Observation of synchrotron radiation in the radio band confirms there is a relativistic electron population in CWBs. Accordingly, CWBs have been suspected sources of high-energy γ-ray emission since the COS-B era. Theoretical models exist that characterize the underlying physical processes leading to particle acceleration and quantitatively predict the non-thermal energy emission observable at Earth. Furthermore, we strive to find evidence of γ-ray emission from a sample of seven CWB systems: WR 11, WR 70, WR 125, WR 137, WR 140, WR 146, and WR 147. Theoretical modelling identified these systems as the most favourable candidates for emitting γ-rays. We make a comparison with existing γ-ray flux predictions and investigate possible constraints. We used 24 months of data from the Large Area Telescope (LAT) on-board the Fermi Gamma Ray Space Telescope to perform a dedicated likelihood analysis of CWBs in the LAT energy range. As a result, we find no evidence of γ-ray emission from any of the studied CWB systems and determine corresponding flux upper limits. For some CWBs the interplay of orbital and stellar parameters renders the Fermi-LAT data not sensitive enough to constrain the parameter space of the emission models. In the cases of WR140 and WR147, the Fermi -LAT upper limits appear to rule out some model predictions entirely and constrain theoretical models over a significant parameter space. A comparison of our findings to the CWB η Car is made.},
doi = {10.1051/0004-6361/201220502},
journal = {Astronomy and Astrophysics},
number = ,
volume = 555,
place = {United States},
year = {2013},
month = {7}
}