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Unusual Black Hole Binary LMC X-3: A Transient High-Mass X-Ray Binary That Is Almost Always On?We have analyzed a rich, multimission, multiwavelength data set from the black hole X-ray binary (BHXB) LMC X-3, covering a new anomalous low state (ALS), during which the source flux falls to an unprecedentedly low and barely detectable level, and a more normal low state. Simultaneous X-ray and UV/optical monitoring data from Swift are combined with pointed observations from the Rossi X-ray Timing Explorer (RXTE) and X-ray Multi- Mirror Mission (XMM-Newton) and light curves from the Monitor of All-Sky X-ray Image (MAXI) instrument to compare the source characteristics during the ALS with those seen during the normal low state. An XMM-Newton spectrum obtained during the ALS can be modeled using an absorbed power law with Gamma = 1.41‚+/- 0.65 and a luminosity of 7.97 x 10(exp 33) erg/s (0.6-5 keV). The Swift X-ray and UV light curves indicate an X-ray lag of approx. 8 days as LMC X-3 abruptly exits the ALS, suggesting that changes in the mass accretion rate from the donor drive the X-ray lag. The normal low state displays an asymmetric profile in which the exit occurs more quickly than the entry, with minimum X-ray flux a factor of approx. 4300 brighter than during the ALS. The UV brightness of LMC X-3 in the ALS is also fainter and less variable than during normal low states. The existence of repeated ALSs in LMC X-3, as well as a comparison with other BHXBs, implies that it is very close to the transient/persistent X-ray source dividing line. We conclude that LMC X-3 is a transient source that is almost always "on."
Document ID
Document Type
Reprint (Version printed in journal)
Torpin, Trevor J.
(Catholic Univ. of America Washington, DC, United States)
Boyd, Patricia T.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Smale, Alan P.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Valencic, Lynne A.
(Johns Hopkins Univ. Baltimore, MD, United States)
Date Acquired
January 17, 2018
Publication Date
October 27, 2017
Publication Information
Publication: The Astrophysical Journal
Publisher: The American Astronomical Society
Volume: 849
Issue: 1
ISSN: 0004-637X
e-ISSN: 1538-4357
Subject Category
Report/Patent Number
Funding Number(s)
Distribution Limits
Simultaneous X-ray and UV/optical monitoring dat
X-ray binary (BHXB) LMC X-3

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