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Simultaneous X-Ray and Radio Monitoring of the Unusual Binary LS I +61°303: Measurements of the Light Curve and High-Energy Spectrum

Harrison, F. A. and Ray, P. S. and Leahy, D. A. and Waltman, E. B. and Pooley, G. G. (2000) Simultaneous X-Ray and Radio Monitoring of the Unusual Binary LS I +61°303: Measurements of the Light Curve and High-Energy Spectrum. Astrophysical Journal, 528 (1). pp. 454-461. ISSN 0004-637X. doi:10.1086/308157.

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The binary system, LS I +61°303, is unusual both because of the dramatic, periodic, radio outbursts, and because of its possible association with the 100 MeV gamma-ray source, 2CG 135+01. We have performed simultaneous radio and Rossi X-Ray Timing Explorer X-ray observations at 11 intervals over the 26.5 day orbit, and in addition searched for variability on timescales ranging from milliseconds to hours. We confirm the modulation of the X-ray emission on orbital timescales originally reported by Taylor et al., and in addition we find a significant offset between the peak of the X-ray and radio flux. We argue that based on these results, the most likely X-ray emission mechanism is inverse Compton scattering of stellar photons off of electrons accelerated at the shock boundary between the relativistic wind of a young pulsar and the Be star wind. In these observations we also detected 2-150 keV flux from the nearby low-redshift quasar QSO 0241+622. Comparing these measurements to previous hard X-ray and gamma-ray observations of the region containing both LS I +61°303 and QSO 0241+622, it is clear that emission from the QSO dominates.

Item Type:Article
Related URLs:
URLURL TypeDescription
Harrison, F. A.0000-0003-2992-8024
Ray, P. S.0000-0002-5297-5278
Additional Information:© 2000. The American Astronomical Society. Received 1999 April 8; accepted 1999 August 10. We would like to thank Keith Jahoda and the RXTE GOF staff for assistance with the RXTE software and background models. Portions of this work were funded by NASA under the RXTE Guest Investigator program. Basic research in X-ray and Radio Astronomy at the Naval Research Laboratory is supported by the Office of Naval Research.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Office of Naval Research (ONR)UNSPECIFIED
Subject Keywords:binaries: close; gamma rays: observations; radio continuum: stars; stars: individual (LS I +61°303)
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2000-42
Issue or Number:1
Record Number:CaltechAUTHORS:20150224-145606151
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:55157
Deposited By: Deborah Miles
Deposited On:24 Feb 2015 23:19
Last Modified:10 Nov 2021 20:42

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