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A NuSTAR Observation of the Reflection Spectrum of the Low-Mass X-Ray Binary 4U 1728-34We report on a simultaneous NuSTAR and Swift observation of the neutron star low-mass X-ray binary 4U 1728-34. We identified and removed four Type I X-ray bursts during the observation in order to study the persistent emission. The continuum spectrum is hard and described well by a blackbody with kT=1.5 keV and a cutoff power law with Lambda = 1.5, and a cutoff temperature of 25 keV. Residuals between 6 and 8 keV provide strong evidence of a broad Fe K(alpha) line. By modeling the spectrum with a relativistically blurred reflection model, we find an upper limit for the inner disk radius of R(sub in) < or = 2R(sub ISCO). Consequently, we find that R(sub NS) < or = 23 km, assuming M = 1.4 Stellar Mass and a = 0.15. We also find an upper limit on the magnetic field of B < or =2 x 10(exp 8) G.
Document ID
20170003453
Document Type
Reprint (Version printed in journal)
Authors
Sleator, Clio C.
(California Univ. Berkeley, CA, United States)
Tomsick, John A.
(California Univ. Berkeley, CA, United States)
King, Ashley L.
(Stanford Univ. Stanford, CA, United States)
Miller, Jon M.
(Michigan Univ. Ann Arbor, MI, United States)
Boggs, Steven E.
(California Univ. Berkeley, CA, United States)
Bachetti, Matteo
(Centre National de la Recherche Scientifique Toulouse, France)
Barret, Didier
(Centre National de la Recherche Scientifique Toulouse, France)
Chenevez, Jerome
(Technical Univ. of Denmark Lyngby, Denmark)
Christensen, Finn E.
(Technical Univ. of Denmark Lyngby, Denmark)
Craig, William W.
(Columbia Univ. New York, NY, United States)
Hailey, Charles J.
(Columbia Univ. New York, NY, United States)
Harrison, Fiona A.
(California Inst. of Tech. Pasadena, CA, United States)
Rahoui, Farid
(Harvard Univ. Cambridge, MA, United States)
Stern, Daniel K.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Walton, Dominic J.
(California Inst. of Tech. Pasadena, CA, United States)
Zhang, William W.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
April 14, 2017
Publication Date
August 18, 2016
Publication Information
Publication: The Astrophysical Journal
Publisher: The American Astronomical
Volume: 827
Issue: 2
ISSN: 0004-637X
e-ISSN: 1538-4357
Subject Category
Astrophysics
Report/Patent Number
GSFC-E-DAA-TN41191
Distribution Limits
Public
Copyright
Other
Keywords
accretion disks
accretion

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