X-ray spectral properties of the accreting millisecond pulsar IGR J17498-2921 during its 2023 outburst

Abstract

We present a comprehensive study of the X-ray spectral properties of the accreting millisecond pulsar IGR J17498$-$2921 during its 2023 outburst. Similar to other accreting millisecond pulsars, the broad-band spectral emission observed quasi-simultaneously by NICER and NuSTAR is well described by an absorbed Comptonized emission with an electron temperature of $\sim$17 keV plus a disk reflection component. The broadening of the disk reflection spectral features, such as a prominent iron emission line at 6.4-6.7 keV, is consistent with the relativistic motion of matter in a disk truncated at $\sim$$21{\mathrm{R}}_{\mathrm{g}}$ from the source, near the Keplerian co-rotation radius. From the high-cadence monitoring data obtained with NICER, we observe that the evolution of the photon index and the temperature of seed photons tracks variations in the X-ray flux. This is particularly evident close to a sudden $\sim$-0.25 cycles jump in the pulse phase, which occurs immediately following an X-ray flux flare and a drop in the pulse amplitude below the $3\sigma$ detection threshold. We also report on the non-detection of optical pulsations with TNG/SiFAP2 from the highly absorbed optical counterpart.

14 pages, 5 figures. Submitted to A&A

References in corpus (23)

• 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
• A model for the waveform behavior of accreting millisecond pulsars: Nearly aligned magnetic fields and moving emission regions
• Timing of the Accreting Millisecond Pulsar XTE J1814-338
• Order in the Chaos: Spin-up and Spin-down during the 2002 Outburst of SAX J1808.4-3658
• Timing an Accreting Millisecond Pulsar: Measuring the Accretion Torque in IGR J00291+5934
• On the timing properties of SAX J1808.4-3658 during its 2015 outburst
• Spin up and phase fluctuations in the timing of the accreting millisecond pulsar XTE J1807-294
• SAX J1808.4-3658: high resolution spectroscopy and decrease of pulsed fraction at low energies
• Spectral and timing properties of IGR J00291+5934 during its 2015 outburst
• Spectral and timing properties of the accreting X-ray millisecond pulsar IGR J17498-2921
• The discovery of the 528.6 Hz accreting millisecond X-ray pulsar MAXI J1816-195
• A broadband look of the Accreting Millisecond X-ray Pulsar SAX J1748.9-2021 using AstroSat and XMM-Newton
• Optical and ultraviolet pulsed emission from an accreting millisecond pulsar
• Precise Orbital Parameters and Anomalous Phase Variations of the Accretion-powered Millisecond Pulsar XTE J1807-294
• MAXI J1957+032: a new accreting millisecond X-ray pulsar in an ultra-compact binary
• Outflows and spectral evolution in the eclipsing AMXP SWIFT J1749.4-2807 with NICER, XMM-Newton and NuSTAR
• The accretion/ejection link in the neutron star X-ray binary 4U 1820-30 I: A boundary layer-jet coupling?
• SRG/ART-XC discovery of SRGAJ144459.2-604207: a well-tempered bursting accreting millisecond X-ray pulsar
• The INTEGRAL view of the pulsating hard X-ray sky: from accreting and transitional millisecond pulsars to rotation-powered pulsars and magnetars
• Spectral analysis of the low-mass X-ray pulsar 4U 1822-371: Reflection component in a high-inclination system
• The 2015 outburst of the accreting millisecond pulsar IGR J17511-3057 as seen by INTEGRAL, Swift and XMM-Newton
• Detection of a strong ~2.5 Hz modulation in the Newly Discovered Millisecond Pulsar MAXI J1816-195

Cited by in corpus (2)

• Disk reflection and energetics from the accreting millisecond pulsar SRGA J144459.2-604207
• The 2025 outburst of IGR J17511-3057: timing and spectral insights from NICER and NuSTAR