Evidence for the photoionization absorption edge in a photospheric radius expansion X-ray burst from GRS 1747$-$312 in Terzan 6

Abstract

Thermonuclear X-ray bursts on the surface of neutron stars (NSs) can enrich photosphere with metals, which may imprint the photoionization edges on the burst spectra. We report here the discovery of absorption edges in the spectra of the type I X-ray burst from the NS low-mass X-ray binary GRS 1747$-$312 in Terzan 6 during observations by the Rossi X-ray Timing Explorer. We find that the edge energy evolves from $9.45\pm 0.51$ keV to $\sim 6$ keV and then back to $9.44\pm 0.40$ keV during the photospheric radius expansion phase and remains at $8.06\pm 0.66$ keV in the cooling tail. The photoionization absorption edges of hydrogen-like Ni, Fe or Fe/Ni mixture and the bound-bound transitions of metals may be responsible for the observed spectral features. The ratio of the measured absorption edge energy in the cooling tail to the laboratory value of hydrogen-like Ni(Fe) edge energy allows us to estimate the gravitational redshift factor $1+z=1.34\pm 0.11$($1+z=1.15\pm 0.09$). The evolution of the spectral parameters during the cooling tail are well-described by the metal-rich atmosphere models. The combined constraints on the NS mass and radius from the direct cooling method and the tidal deformability strongly suggest very high atmospheric abundance of the iron group elements and limit the distance to the source to $11\pm 1$ kpc.

arXiv commentmatches the published version

References in corpus (36)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Neutron Star Observations: Prognosis for Equation of State Constraints
• Gravitational-wave constraints on the neutron-star-matter Equation of State
• Thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer
• Calibration of the Rossi X-ray Timing Explorer Proportional Counter Array
• The Neutron Star Mass-Radius Relation and the Equation of State of Dense Matter
• The Dense Matter Equation of State from Neutron Star Radius and Mass Measurements
• Photospheric radius expansion X-ray bursts as standard candles
• EXO 0748-676 Rules out Soft Equations of State for Neutron Star Matter
• The Mass and Radius of the Neutron Star in EXO 1745-248
• Carbon Flashes in the Heavy Element Ocean on Accreting Neutron Stars
• Measurement of the Radius of Neutron Stars with High S/N Quiescent Low-mass X-ray Binaries in Globular Clusters
• Neutron star stiff equation of state derived from cooling phases of the X-ray burster 4U 1724-307
• Neutron star mass and radius measurements from atmospheric model fits to X-ray burst cooling tail spectra
• Near-IR properties of 24 Globular Clusters in the Galactic Bulge
• Evidence for accretion rate change during type I X-ray bursts
• X-ray bursting neutron star atmosphere models: spectra and color corrections
• The effect of accretion on the measurement of neutron star mass and radius in the low-mass X-ray binary 4U 1608-52
• The Evolution of the Accretion Disk around 4U 1820-30 During a Superburst
• A relativistically smeared spectrum in the neutron star X-ray Binary 4U 1705-44: Looking at the inner accretion disc with X-ray spectroscopy
• Evidence of heavy-element ashes in thermonuclear X-ray bursts with photospheric superexpansion
• A bright thermonuclear X-ray burst simultaneously observed with Chandra and RXTE
• Intermediate long X-ray bursts from the ultra-compact binary source SLX 1737-282
• The direct cooling tail method for X-ray burst analysis to constrain neutron star masses and radii
• X-ray Reflection and An Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143
• Bursts, eclipses, dips and a refined position for the luminous low-mass X-ray binary in the globular cluster Terzan 6
• BeppoSAX observations of the X-ray pulsar MAXI J1409-619 in low state: discovery of cyclotron resonance features
• Advances in the RXTE Proportional Counter Array Calibration: Nearing the Statistical Limit
• X-Raying an Accretion Disk in Realtime: the Evolution of Ionized Reflection during a Superburst from 4U 1636-536
• The Be/X-ray Binary Swift J1626.6-5156 as a Variable Cyclotron Line Source
• Detection of burning ashes from thermonuclear X-ray bursts
• Measuring the basic parameters of neutron stars using model atmospheres
• An Ultra Low Mass and Small Radius Compact Object in 4U 1746-37?
• A peculiar type-I X-ray burst from GRS 1747-312
• Models of neutron star atmospheres enriched with nuclear burning ashes
• Simultaneous constraints on the mass and radius of Aql X-1 from quiescence and X-ray burst observations

Cited by in corpus (16)

• The Multi-INstrument Burst ARchive (MINBAR)
• The Galactic LMXB Population and the Galactic Centre Region
• NICER Discovers Spectral Lines During Photospheric Radius Expansion Bursts from 4U 1820-30: Evidence for Burst-driven Winds
• Dense Matter in Neutron Stars with eXTP
• NICER observations of the evidence of Poynting-Robertson drag and disk reflection during type I X-ray bursts from 4U 1636$-$536
• Type I X-ray bursts' spectra and fuel composition from the atoll and transient source 4U 1730$-$22
• Expanded atmospheres and winds in Type I X-ray bursts from accreting neutron stars
• The imprint of convection on Type I X-ray bursts: Pauses in photospheric radius expansion lightcurves
• Quenching and recovery of persistent X-ray emission during a superburst in 4U 1820$-$30
• Emission and Absorption Lines in Photospheric Radius Expansion Bursts of 4U 1820$-$30
• A transition from mixed-fuel to pure-helium thermonuclear bursts in Terzan 5 X-3/Swift J174805.3-244637
• Mass-Radius Constraints for 2S 0918-549 from an RXTE Superexpansion Burst: A Direct Cooling-Tail Analysis
• An unusual type-I X-ray burst from the neutron star X-ray binary IGR J17591-2342: a double-photospheric-radius-expansion burst?
• Influence of the gravitational darkening effect on the spectrum of a hot, rapidly rotating neutron star. II. Iron lines
• Neutron star atmospheres composed of fusion ashes
• Long thermonuclear burst driven thermal-viscous instability of accretion disk: triggering an outburst-like X-ray flare