Spectral Analysis of the Egress and Ingress Phases of Cen X-3 with XRISM/Resolve
Abstract
We investigate the phase-resolved X-ray spectral evolution of the high-mass X-ray binary Cen X-3 across eclipse ingress and egress, using two out-of-eclipse intervals as references, to constrain the absorbing material and Fe K emitting regions with high-resolution XRISM/Resolve spectroscopy. We model the spectra with SPEX, including interstellar and local wind absorption, a power-law and blackbody continuum, disk reflection, and Gaussian components for Fe XXV and Fe XXVI. We compare the orbital variation of the absorbing column with a smooth CAK wind model and investigate the variability of the Fe K alpha line width. The local absorbing column varies by nearly two orders of magnitude, from N_H^local = 4.25 x 10^22 cm^-2 during pre-ingress to 5.9 x 10^23 cm^-2 at ingress. The excess ingress absorption cannot be reproduced by a smooth wind model alone, suggesting a localized overdense structure along the line of sight. The Fe K alpha width varies from approximately 510 km s^-1 during pre-ingress to 1400 km s^-1 during egress, with intermediate, statistically indistinguishable values of approximately 900 km s^-1 during ingress and post-egress. Highly ionized Fe XXV and Fe XXVI emission is detected throughout the orbit, although fewer components are resolved during ingress. These diagnostics reveal a complex circumstellar environment with localized dense material and multiple reprocessing regions. The results demonstrate the capability of XRISM/Resolve to probe the geometry and kinematics of accretion environments in eclipsing high-mass X-ray binaries.
Related
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BibTeX
@misc{planellesvillalva2026spectral,
title = {{Spectral Analysis of the Egress and Ingress Phases of Cen X-3 with XRISM/Resolve}},
author = {J. Planelles-Villalva and L. Gu and J. J. Rodes-Roca and G. Sanjurjo-Ferrín and J. de Plaa and J. M. Torrejón and F. S. Porter and Y. Mochizuki and M. Loewenstein and E. Costantini},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.23748},
eprint = {2609.23748},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.23748},
}
RIS
TY - UNPB
TI - Spectral Analysis of the Egress and Ingress Phases of Cen X-3 with XRISM/Resolve
AU - J. Planelles-Villalva
AU - L. Gu
AU - J. J. Rodes-Roca
AU - G. Sanjurjo-Ferrín
AU - J. de Plaa
AU - J. M. Torrejón
AU - F. S. Porter
AU - Y. Mochizuki
AU - M. Loewenstein
AU - E. Costantini
PY - 2026
DA - 2026/09/22
PB - arXiv
DO - 10.48550/arxiv.2609.23748
UR - https://arxiv.org/abs/2609.23748
AB - We investigate the phase-resolved X-ray spectral evolution of the high-mass X-ray binary Cen X-3 across eclipse ingress and egress, using two out-of-eclipse intervals as references, to constrain the absorbing material and Fe K emitting regions with high-resolution XRISM/Resolve spectroscopy. We model the spectra with SPEX, including interstellar and local wind absorption, a power-law and blackbody continuum, disk reflection, and Gaussian components for Fe XXV and Fe XXVI. We compare the orbital variation of the absorbing column with a smooth CAK wind model and investigate the variability of the Fe K alpha line width. The local absorbing column varies by nearly two orders of magnitude, from N_H^local = 4.25 x 10^22 cm^-2 during pre-ingress to 5.9 x 10^23 cm^-2 at ingress. The excess ingress absorption cannot be reproduced by a smooth wind model alone, suggesting a localized overdense structure along the line of sight. The Fe K alpha width varies from approximately 510 km s^-1 during pre-ingress to 1400 km s^-1 during egress, with intermediate, statistically indistinguishable values of approximately 900 km s^-1 during ingress and post-egress. Highly ionized Fe XXV and Fe XXVI emission is detected throughout the orbit, although fewer components are resolved during ingress. These diagnostics reveal a complex circumstellar environment with localized dense material and multiple reprocessing regions. The results demonstrate the capability of XRISM/Resolve to probe the geometry and kinematics of accretion environments in eclipsing high-mass X-ray binaries.
ER -