A NuSTAR OBSERVATION OF THE REFLECTION SPECTRUM OF THE LOW-MASS X-RAY BINARY 4U 1728-34

作者：Sleator Clio C^*; Tomsick John A; King Ashley L; Miller Jon M; Boggs Steven E; Bachetti Matteo; Barret Didier; Chenevez Jerome; Christensen Finn E; Craig William W; Hailey Charles J; Harrison Fiona A; Rahoui Farid; Stern Daniel K; Walton Dominic J; Zhang William W

来源：Astrophysical Journal, 2016, 827(2): 134.

DOI：10.3847/0004-637X/827/2/134

• accretion, accretion disks
• stars: neutron
• X-rays: binaries

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 Gamma = 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-in <= 2R(ISCO). Consequently, we find that R-NS <= 23 km, assuming M =1.4 M-circle dot and alpha = 0.15. We also find an upper limit on the magnetic field of B <= 2 x 10(8) G.

• 出版日期2016-8-20