DISCOVERY OF THE THIRD TRANSIENT X-RAY BINARY IN THE GALACTIC GLOBULAR CLUSTER TERZAN 5
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Bahramian-2014-Discovery of the thi.pdf
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Author(s)
Bahramian, Arash
Heinke, C. O.
Sivakoff, Gregory R.
Altamirano, Diego
Wijnands, Rudy
Homan, Jeroen
Linares, Manuel Alegret
Pooley, David
Degenaar, N.
Gladstone, Jeanette C.
Date Issued
December 2013
Journal
The Astrophysical Journal
Publisher
IOP Publishing
Citation
Bahramian, Arash, Craig O. Heinke, Gregory R. Sivakoff, Diego Altamirano, Rudy Wijnands, Jeroen Homan, Manuel Linares, David Pooley, Nathalie Degenaar, and Jeanette C. Gladstone. “DISCOVERY OF THE THIRD TRANSIENT X-RAY BINARY IN THE GALACTIC GLOBULAR CLUSTER TERZAN 5.” The Astrophysical Journal 780, no. 2 (December 17, 2013): 127. © 2014 The American Astronomical Society
Version
Final published version
Abstract
We report and study the outburst of a new transient X-ray binary (XRB) in Terzan 5, the third detected in this globular cluster, Swift J174805.3-244637 or Terzan 5 X-3. We find clear spectral hardening in Swift/XRT data during the outburst rise to the hard state, thanks to our early coverage (starting at L[subscript X] ~ 4 × 10[superscript 34] erg s[superscript –1]) of the outburst. This hardening appears to be due to the decline in relative strength of a soft thermal component from the surface of the neutron star (NS) during the rise. We identify a Type I X-ray burst in Swift/XRT data with a long (16 s) decay time, indicative of hydrogen burning on the surface of the NS. We use Swift/BAT, MAXI/GSC, Chandra/ACIS, and Swift/XRT data to study the spectral changes during the outburst, identifying a clear hard-to-soft state transition. We use a Chandra/ACIS observation during outburst to identify the transient's position. Seven archival Chandra/ACIS observations show evidence for variations in Terzan 5 X-3's nonthermal component but not the thermal component during quiescence. The inferred long-term time-averaged mass accretion rate, from the quiescent thermal luminosity, suggests that if this outburst is typical and only slow cooling processes are active in the NS core, such outbursts should recur every ~10 yr.
MIT Department
MIT Kavli Institute for Astrophysics and Space Research
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DOI of Published Version
https://doi.org/10.1088/0004-637X/780/2/127
