Work

Resolving Structure within the Iron Line Profile of Serpens X-1 with XRISM and NuSTAR

Year: 2026

Type: article

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.

Source: The Astrophysical Journal

DOI: 10.3847/1538-4357/aea28b

Authors: H. Hall, R. M. Ludlam, E. Cackett, J. M. Miller, J. A. García

Institutions: Wayne State University, University of Michigan, California Institute of Technology, Goddard Space Flight Center

Language: English

Topic: Astrophysical Phenomena and Observations

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $4,499

Funders: National Aeronautics and Space Administration, Goddard Space Flight Center, Astrophysics Science Division