A VARIABLE NEAR-INFRARED COUNTERPART TO THE NEUTRON-STAR LOW-MASS X-RAY BINARY 4U 1705 – 440

Author(s)
Homan, Jeroen; Kaplan, David L.; van den Berg, Maureen; Young, Andrew J.
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Abstract
We report the discovery of a near-infrared (NIR) counterpart to the persistent neutron-star low-mass X-ray binary 4U 1705 – 440, at a location consistent with its recently determined Chandra X-ray position. The NIR source is highly variable, with Ks -band magnitudes varying between 15.2 and 17.3 and additional J- and H-band observations revealing color variations. A comparison with contemporaneous X-ray monitoring observations shows that the NIR brightness correlates well with X-ray flux and X-ray spectral state. We also find possible indications of a change in the slope of the NIR/X-ray flux relation among different X-ray states. We discuss and test various proposed mechanisms for the NIR emission from neutron-star low-mass X-ray binaries and conclude that the NIR emission in 4U 1705 – 440 is most likely dominated by X-ray heating of the outer accretion disk and the secondary star.
Date issued
2009-02
URI
http://hdl.handle.net/1721.1/96196
Department
MIT Kavli Institute for Astrophysics and Space Research
Journal
Astrophysical Journal
Publisher
Institute of Physics/American Astronomical Society
Citation
Homan, Jeroen, David L. Kaplan, Maureen van den Berg, and Andrew J. Young. “A VARIABLE NEAR-INFRARED COUNTERPART TO THE NEUTRON-STAR LOW-MASS X-RAY BINARY 4U 1705 – 440.” The Astrophysical Journal 692, no. 1 (February 10, 2009): 73–80. © 2009 American Astronomical Society.
Version: Final published version
ISSN
0004-637X
1538-4357
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