Resolving Structure within the Iron Line Profile of Serpens X-1 with XRISM and NuSTAR
4 affiliations
- 1Wayne State University
- 2University of Michigan
- 3California Institute of Technology
- 4NASA Goddard Space Flight Center
Abstract
We present the first simultaneous XRISM and NuSTAR observations of the neutron star low-mass X-ray binary (LXMB) Serpens X-1. We perform spectral modeling on the joint observations of XRISM/Resolve, XRISM/Xtend, and NuSTAR, testing Comptonization and double thermal continuum model prescriptions. We find that a hybrid double thermal model adequately describes the underlying continuum of the source, while the Comptonization models predict largely unphysical parameter values. We perform reflection modeling and confirm with tight constraints an inclination of 5 ∘ ± 1 ∘ and an inner disk radius of 6.6 ± 0.6 R g for the source. We show that the spectral resolution of XRISM/Resolve allows for the determination of a unique inner disk radius, which has the potential to constrain neutron star spin in other systems. We discuss discrepancies in spectral shape between XRISM/Resolve and NuSTAR above ∼8 keV. We also present light-curve and spectral analyses of eight Type I X-ray bursts that occurred during the observations.
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BibTeX
@article{hall2026resolving,
title = {{Resolving Structure within the Iron Line Profile of Serpens X-1 with XRISM and NuSTAR}},
author = {H. Hall and R. M. Ludlam and E. Cackett and J. M. Miller and J. A. García},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-4357/aea28b},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aea28b},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Resolving Structure within the Iron Line Profile of Serpens X-1 with XRISM and NuSTAR
AU - H. Hall
AU - R. M. Ludlam
AU - E. Cackett
AU - J. M. Miller
AU - J. A. García
PY - 2026
DA - 2026/10/05
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aea28b
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aea28b
AB - We present the first simultaneous XRISM and NuSTAR observations of the neutron star low-mass X-ray binary (LXMB) Serpens X-1. We perform spectral modeling on the joint observations of XRISM/Resolve, XRISM/Xtend, and NuSTAR, testing Comptonization and double thermal continuum model prescriptions. We find that a hybrid double thermal model adequately describes the underlying continuum of the source, while the Comptonization models predict largely unphysical parameter values. We perform reflection modeling and confirm with tight constraints an inclination of 5 ∘ ± 1 ∘ and an inner disk radius of 6.6 ± 0.6 R g for the source. We show that the spectral resolution of XRISM/Resolve allows for the determination of a unique inner disk radius, which has the potential to constrain neutron star spin in other systems. We discuss discrepancies in spectral shape between XRISM/Resolve and NuSTAR above ∼8 keV. We also present light-curve and spectral analyses of eight Type I X-ray bursts that occurred during the observations.
SN - 0004-637X
SN - 1538-4357
ER -