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arXiv · 2401.09664

X-ray Iron absorption line in Swift J1858.6-0814

Kazumi Asai·Tatehiro Mihara·Kento Sakai·Aya Kubota
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Abstract

We present the spectral analysis of bright steady states in an outburst of the transient neutron star low-mass X-ray binary (NS-LMXB) Swift J1858.6-0814 observed with NICER. We detected an ionized iron K absorption line (H-like Fe) at 6.97keV in the spectrum. We estimated the photoionization parameter using the ratio of the equivalent widths (EWs) of the FeXXVI (H-like) (17+\-5eV) and FeXXV (He-like) (<3eV) and discuss the origin of the iron absorption line. The irradiated gas producing the absorption line would locate within (3-6)*1E9cm from the X-ray source. We suggest that the observed H-like Fe absorption line originates from the highly-ionized gas in the inner accretion disk in Swift J1858.6-0814.

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Kazumi Asai, Tatehiro Mihara, Kento Sakai, Aya Kubota. 2024-01-18. X-ray Iron absorption line in Swift J1858.6-0814. https://doi.org/10.1093/pasj%2Fpsad082

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