Spectral and timing properties of the accreting X-ray millisecond pulsar IGR J17511-3057

Abstract

IGR J17511-3057 is the second X-ray transient accreting millisecond pulsar discovered by INTEGRAL. It was in outburst for about a month from September 13, 2009. The broad-band average spectrum is well described by thermal Comptonization with an electron temperature of kT_e ~ 25 keV, soft seed photons of kT_bb ~ 0.6 keV, and Thomson optical depth τ_T ~ 2 in a slab geometry. During the outburst the spectrum stays remarkably stable with plasma and soft seed photon temperatures and scattering optical depth being constant within errors. We fitted the outburst profile with the exponential model, and using the disk instability model we inferred the outer disk radius to be (4.8 - 5.4) \times 1010 cm. The INTEGRAL and RXTE data reveal the X-ray pulsation at a period of 4.08 milliseconds up to ~ 120 keV. The pulsed fraction is shown to decrease from ~22% at 3 keV to a constant pulsed fraction of ~17-18% between 7-30 keV, and then to decrease again down to ~13% at 60 keV. The nearly sinusoidal pulses show soft lags monotonically increasing with energy to about 0.2 ms at 10-20 keV similar to those observed in other accreting pulsars. The short burst profiles indicate hydrogen-poor material at ignition, which suggests either that the accreted material is hydrogen-deficient, or that the CNO metallicity is up to a factor of 2 times solar. However, the variation of burst recurrence time as a function of m (inferred from the X-ray flux) is much smaller than predicted by helium-ignition models.

11 Pages, 10 Figures, 3 Tables, Submitted to A&A

References in corpus (7)

• Discovery of luminous pulsed hard X-ray emission from anomalous X-ray pulsars 1RXS J1708-4009, 4U 0142+61 and 1E 2259+586 by INTEGRAL and RXTE
• A decade of timing an accretion-powered millisecond pulsar: The continuing spin down and orbital evolution of SAX J1808.4-3658
• A Double Outburst from IGR J00291+5934: Implications for Accretion Disk Instability Theory
• Mass transfer during low mass X-ray transient decays
• Deviations from the Flux-Recurrence Time Relationship in GS 1826-238: Potential Transient Spectral Changes
• Simultaneous INTEGRAL and RXTE observations of the accreting millisecond pulsar HETE J1900.1-2455
• Modeling pulse profiles of accreting millisecond pulsars

Cited by in corpus (26)

• The soft gamma-ray pulsar population: an high-energy overview
• Detecting gravitational waves from mountains on neutron stars in the Advanced Detector Era
• The nature of very faint X-ray binaries; hints from light curves
• Spectral and timing properties of IGR J00291+5934 during its 2015 outburst
• The 2015 outburst of the accretion-powered pulsar IGR J00291+5934: INTEGRAL and Swift observations
• Spectral and timing properties of the accreting X-ray millisecond pulsar IGR J17498-2921
• High-energy characteristics of the accretion-powered millisecond pulsar IGR J17591-2342 during its 2018 outburst
• Indications for a slow rotator in the Rapid Burster from its thermonuclear bursting behaviour
• The 2015 outburst of the accreting millisecond pulsar IGR J17511-3057 as seen by INTEGRAL, Swift and XMM-Newton
• The INTEGRAL view of the pulsating hard X-ray sky: from accreting and transitional millisecond pulsars to rotation-powered pulsars and magnetars
• Swift J1734.5-3027: a new long type-I X-ray bursting source
• Discovery of Polarized X-Ray Emission from the Accreting Millisecond Pulsar SRGA J144459.2-604207
• Timing of the accreting millisecond pulsar IGR J17591-2342: evidence of spin-down during accretion
• Kinetic equilibria of relativistic collisionless plasmas in the presence of non-stationary electromagnetic fields
• Polarized radiation from an accretion shock in accreting millisecond pulsars using exact Compton scattering formalism
• Broadband X-ray timing and spectral characteristics of the accretion-powered millisecond X-ray pulsar MAXI J1816$-$195
• Covariant formulation of spatially non-symmetric kinetic equilibria in magnetized astrophysical plasmas
• Robust inference of neutron-star parameters from thermonuclear burst observations
• Broad-band X-ray spectra and timing of the accretion-powered millisecond pulsar Swift J1756.9$-$2508 during its 2018 and 2019 outbursts
• Disk reflection and energetics from the accreting millisecond pulsar SRGA J144459.2-604207
• Broad-band X-ray spectral and timing properties of the accreting millisecond X-ray pulsar IGR J17498$-$2921 during the 2023 outburst
• Timing and spectral studies of SRGA J144459.2$-$604207 with NICER, Einstein Probe, IXPE, NuSTAR, Insight-HXMT and INTEGRAL during its 2024 outburst
• Connecting the m-dots: accretion rates and thermonuclear burst recurrence times on neutron stars and white dwarfs
• Detection of low-luminosity X-ray pulsations from the accreting millisecond pulsar IGR J17511-3057: An ever-thinning thread between bright accretion and sub-luminous states
• Updated Spin and Orbital Parameters and Energy Dependent Pulse Behaviors of the Accreting Millisecond X-ray Pulsar IGR J17591$-$2342
• The 2025 outburst of IGR J17511-3057: timing and spectral insights from NICER and NuSTAR