Accretion disk signatures in Type I X-ray Bursts: prospects for future missions

Abstract

Type I X-ray bursts and superbursts from accreting neutron stars illuminate the accretion disk and produce a reflection signal that evolves as the burst fades. Examining the evolution of reflection features in the spectra will give insight into the burst-disk interaction, a potentially powerful probe of accretion disk physics. At present, reflection has been observed during only two bursts of exceptional duration. We investigate the detectability of reflection signatures with four of the latest well-studied X-ray observatory concepts: Hitomi, NICER, Athena, and LOFT. Burst spectra are modeled for different values for the flux, temperature, and the disk ionization parameter, which are representative for most known bursts and sources. The effective area and through-put of a Hitomi-like telescope are insufficient for characterizing burst reflection features. NICER and Athena will detect reflection signatures in Type I bursts with peak fluxes $\ge 10^{-7.5}$ erg cm${}^{-2}$ s${}^{-1}$, and also effectively constrain the reflection parameters for bright bursts with fluxes of $10^{-7}$ erg cm${}^{-2}$ s${}^{-1}$ in exposures of several seconds. Thus, these observatories will provide crucial new insight into the interaction of accretion flows and X-ray bursts. For sources with low line-of-sight absorption, the wide band-pass of these instruments allows for the detection of soft X-ray reflection features, which are sensitive to the disk metallicity and density. The large collecting area that is part of the LOFT design would revolutionize the field by tracing the evolution of the accretion geometry in detail throughout short bursts.

14 pages, 13 figures, accepted for publication in ApJ

References in corpus (18)

• Neutron Star Observations: Prognosis for Equation of State Constraints
• Modelling the behaviour of accretion flows in X-ray binaries
• Thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer
• Relativistic X-ray Lines from the Inner Accretion Disks Around Black Holes
• Six new candidate ultracompact X-ray binaries
• Models of Type I X-ray Bursts from GS 1826-24: A Probe of rp-Process Hydrogen Burning
• Nucleosynthesis in Type I X-ray Bursts
• The effect of accretion on the measurement of neutron star mass and radius in the low-mass X-ray binary 4U 1608-52
• Evidence for enhanced persistent emission during sub-Eddington thermonuclear bursts
• The influence of accretion geometry on the spectral evolution during thermonuclear (type-I) X-ray bursts
• First superburst from a classical low-mass X-ray binary transient
• Anisotropy of X-ray bursts from neutron stars with concave accretion disks
• X-Raying an Accretion Disk in Realtime: the Evolution of Ionized Reflection during a Superburst from 4U 1636-536
• Multiwavelength Observations of EXO 0748-676 - I. Reprocessing of X-ray Bursts
• Characterizing the Evolving X-Ray Spectral Features During a Superburst from 4U 1636-536
• Long tails on thermonuclear X-ray bursts from neutron stars: a signature of inward heating?
• Probing the effects of a thermonuclear X-ray burst on the neutron star accretion flow with NuSTAR
• The LOFT perspective on neutron star thermonuclear bursts

Cited by in corpus (9)

• Accretion disks and coronae in the X-ray flashlight
• Observatory science with eXTP
• NICER Observes the Effects of an X-Ray Burst on the Accretion Environment in Aql X-1
• X-ray Reflection and An Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143
• Neutron star cooling and the rp process in thermonuclear X-ray bursts
• Paving the way to simultaneous multi-wavelength astronomy
• Evolution of accretion disc reflection spectra due to a Type I X-ray burst
• STROBE-X: A probe-class mission for X-ray spectroscopy and timing on timescales from microseconds to years
• QPO signatures of disk restoration after type-I X-ray bursts from 4U~1636$-$536