NuSTAR DISCOVERY OF A CYCLOTRON LINE IN THE ACCRETING X-RAY PULSAR IGR J16393-4643

作者：Bodaghee Arash^*; Tomsick John A; Fornasini Francesca M; Krivonos Roman; Stern Daniel; Mori Kaya; Rahoui Farid; Boggs Steven E; Christensen Finn E; Craig William W; Hailey Charles J; Harrison Fiona A; Zhang William W

来源：Astrophysical Journal, 2016, 823(2): 146.

DOI：10.3847/0004-637X/823/2/146

• accretion, accretion disks
• gamma-ray burst: general
• stars: neutron
• X-rays: binaries
• X-rays: individual (IGR J16393-4643)

The high-mass X-ray binary and accreting X-ray pulsar IGR J16393-4643 was observed by the Nuclear Spectroscope Telescope Array in the 3-79 keV energy band for a net exposure time of 50 ks. We present the results of this observation which enabled the discovery of a cyclotron resonant scattering feature with a centroid energy of 29.3(-1.3)(+1.1) keV. This allowed us to measure the magnetic field strength of the neutron star for the first time: B = (2.5 +/- 0.1) x 1012 G. The known pulsation period is now observed at 904.0 +/- 0.1 s. Since 2006, the neutron star has undergone a long-term spin-up trend at a rate of (P) over dot = -2 x 10(-8) s s(-1) (0.6 s per year, or a frequency derivative of (v) over dot = 3 x 10(-14) Hz s(-1)). In the power density spectrum, a break appears at the pulse frequency which separates the zero slope at low frequency from the steeper slope at high frequency. This addition of angular momentum to the neutron star could be due to the accretion of a quasi-spherical wind, or it could be caused by the transient appearance of a prograde accretion disk that is nearly in corotation with the neutron star whose magnetospheric radius is around 2 x 10(8) cm.

• 出版日期2016-6-1