Ways to constrain neutron star equation of state models using relativistic disc lines

Abstract

Relativistic spectral lines from the accretion disc of a neutron star low-mass X-ray binary can be modelled to infer the disc inner edge radius. A small value of this radius tentatively implies that the disc terminates either at the neutron star hard surface, or at the innermost stable circular orbit (ISCO). Therefore an inferred disc inner edge radius either provides the stellar radius, or can directly constrain stellar equation of state (EoS) models using the theoretically computed ISCO radius for the spacetime of a rapidly spinning neutron star. However, this procedure requires numerical computation of stellar and ISCO radii for various EoS models and neutron star configurations using an appropriate rapidly spinning stellar spacetime. We have fully general relativistically calculated about 16000 stable neutron star structures to explore and establish the above mentioned procedure, and to show that the Kerr spacetime is inadequate for this purpose. Our work systematically studies the methods to constrain EoS models using relativistic disc lines, and will motivate future X-ray astronomy instruments.

6 pages, 9 figures, published in MNRAS

References in corpus (12)

• Neutron Star Observations: Prognosis for Equation of State Constraints
• Constraining Black Hole Spin Via X-ray Spectroscopy
• Relativistic X-ray Lines from the Inner Accretion Disks Around Black Holes
• Relativistic iron emission lines in neutron star low-mass X-ray binaries as probes of neutron star radii
• Broad relativistic iron emission line observed in SAX J1808.4-3658
• XMM-Newton detects a relativistically broadened iron line in the spectrum of the ms X-ray pulsar SAX J1808.4-3658
• Evidence of a Broad Relativistic Iron Line from the Neutron Star Low-Mass X-ray Binary Serpens X-1
• A relativistically smeared spectrum in the neutron star X-ray Binary 4U 1705-44: Looking at the inner accretion disc with X-ray spectroscopy
• Disk reflection signatures in the spectrum of the bright Z-source GX 340+0
• Realistic Exact Solution for the Exterior Field of a Rotating Neutron Star
• Innermost stable circular orbits around magnetized rotating massive stars
• Approximate analytic expressions for circular orbits around rapidly rotating compact stars

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• A test of the nature of the Fe K Line in the neutron star low-mass X-ray binary Serpens X-1
• On the disc reflection spectroscopy of NS LMXB Serpens~X-1: analysis of a recent NuSTAR observation
• Universal relations for innermost stable circular orbits around rapidly rotating neutron stars
• High-frequency variability in neutron-star low-mass X-ray binaries
• Pulse Profile Modeling of Thermonuclear Burst Oscillations I: The Effect of Neglecting Variability
• Study of the reflection spectrum of the bright atoll source GX 3+1 with NuSTAR
• The Spin of a Newborn Black Hole: Swift J1728.9-3613
• Evidence of disc reflection in the X-ray spectrum of the neutron star low mass X-ray binary 4U 1636-536
• Neutron Star Radius-to-mass Ratio from Partial Accretion Disc Occultation as Measured through Fe K$\alpha$ Line Profiles
• Innermost stable circular orbits of neutron stars in dilatonic-Einstein-Gauss-Bonnet theory
• Relativistic disc line: a tool to constrain neutron star equation of state models