http://arxiv.org/abs/1811.08140
We have analyzed X-ray data of SMC X-1 obtained with \textit{Suzaku}, and discovered a combination of an absorption line and an underlying broadened emission line centered at 6.4 keV in an observation performed on May 19, 2012. This absorption line is centered at $6.61_{-0.03}^{+0.02}$~keV with an absorption strength of $5.9_{-1.4}^{+1.7}$, naturally interpreted as an He${\alpha}$ resonance line of Fe at 6.7~keV that has a redshift of $4000{-1300}^{+1400}\;\mathrm{km\;s^{-1}}$. Although \textit{Suzaku} observed this system ten times during 11 months in 2011–2012, the absorption feature has been seen only in a single observation when the NS was in a rising phase of the super-orbital modulation, which can be regarded as an egress from occultation by an extended accretion disk. We therefore attribute the line to a low density, highly ionized absorber in an accretion disk corona arising from the disk illuminated by the NS’s intense X-rays. This interpretation also agrees with a discussion on the photoionization degree and the line depth.
M. Kubota, H. Odaka, T. Tamagawa, et. al.
Wed, 21 Nov 18
59/74
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