Publication Date:
2019-07-13
Description:
We 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.
Keywords:
Astrophysics
Type:
GSFC-E-DAA-TN41191
,
The Astrophysical Journal (ISSN 0004-637X) (e-ISSN 1538-4357); 827; 2; 134
Format:
text
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