A variable near-infrared counterpart to the neutron-star low-mass X-ray binary 4U 1705-440

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 K_s-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 for a change in the slope of the nIR/X-ray flux relation between 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.

Accepted for publication in ApJ

References in corpus (6)

• Thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer
• Global optical/infrared - X-ray correlations in X-ray binaries: quantifying disc and jet contributions
• Evaluating Spectral Models and the X-ray States of Neutron-Star X-ray Transients
• Evidence for a jet contribution to the optical/infrared light of neutron star X-ray binaries
• Spitzer Reveals Infrared Optically-Thin Synchrotron Emission from the Compact Jet of the Neutron Star X-Ray Binary 4U 0614+091
• BeppoSAX observation of 4U 1705-44: detection of hard X-ray emission in the soft state

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• The Chaotic Long-term X-ray Variability of 4U 1705--44
• Large amplitude variability from the persistent ultracompact X-ray binary in NGC 1851
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• The Megasecond Chandra X-Ray Visionary Project Observation of NGC 3115 (II): properties of point sources
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