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arXiv · 2512.00589

XRISM Observations of Accretion Disk Corona in Cyg X-2

Misaki Mizumoto·Hiromitsu Takahashi·Ehud Behar·Rozenn Boissay-Malaquin·Lia Corrales·Elisa Costantini·Maria Diaz-Trigo·Eric D. Miller·Jon M. Miller
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Abstract

We present the high-resolution X-ray spectrum of the Z-source Cygnus X-2, obtained with X-Ray Imaging and Spectroscopy Mission (XRISM). The observations have enabled a precise characterization of the Fe-K emission lines from the accretion disk corona (ADC) and a possible detection of an ultra-fast outflow (UFO). The ADC component has at least two distinct regions. The Fe-K emission lines are remarkably broad, with a velocity dispersion of $\sigma_v=2300^{+900}_{-700}$~km~s$^{-1}$. This can be larger than what was observed in previous Chandra observations ($1120\pm870$~km~s$^{-1}$) and recent XRISM observations of the similar Z-source GX 340+0 (360--800~km~s$^{-1}$). Furthermore, we marginally detect a blueshifted absorption feature, which we identify as either \ion{Fe}{26} or \ion{Fe}{25}, with outflow velocities of $-0.29c$ or $-0.26c$, respectively. The mass loss rate is $\dot{M}\sim10^{-8}M_\odot\,\mathrm{yr}^{-1}$. Our findings suggest that the ADC in Cyg X-2 has a kinematically active environment with a high degree of turbulence and kinetic energy.

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Misaki Mizumoto, Hiromitsu Takahashi, Ehud Behar, Rozenn Boissay-Malaquin, Lia Corrales, Elisa Costantini, Maria Diaz-Trigo, Eric D. Miller, Jon M. Miller. 2025-11-29. XRISM Observations of Accretion Disk Corona in Cyg X-2. https://arxiv.org/abs/2512.00589

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