Broad-band X-ray spectral and timing properties of the accreting millisecond X-ray pulsar IGR J17498$-$2921 during the 2023 outburst

Abstract

We report on the broadband spectral and timing properties of the accreting millisecond X-ray pulsar IGR J17498$-$2921 during its April 2023 outburst using data from NICER (1$-$10 keV), NuSTAR (3$-$79 keV), Insight-HXMT (2$-$150 keV), and INTEGRAL (30$-$150 keV). We detect significant 401 Hz pulsations across the 0.5$-$150 keV band. The pulse fraction increases from $\sim$2% at 1 keV to $\sim$13% at 66 keV. Five type-I X-ray bursts have been detected, including three photospheric radius expansion bursts, with a rise time of $\sim$2 s and an exponential decay time of $\sim$5 s. The recurrence time is $\sim$9.1 h, which can be explained by unstable thermonuclear burning of hydrogen-deficient material on the neutron star surface. The quasi-simultaneous 1$-$150 keV broadband spectra from NICER, NuSTAR, and INTEGRAL can be well fitted by an absorbed reflection model, relxillCp, and a Gaussian line of instrumental origin. The Comptonized emission from the hot corona is characterized by a photon index $\Gamma$ of $\sim$1.8 and an electron temperature $k{T}_{\mathrm{e}}$ of $\sim$40 keV. We obtain a low inclination angle $i\sim 34^{\circ }$. The accretion disk shows properties of strong ionization, $\log (\xi /\mathrm{erg}\mathrm{cm}{\mathrm{s}}^{-1})\sim 4.5$, over-solar abundance, $A_{\mathrm{Fe}}\sim 7.7$, and high density, $\log (n_{\mathrm{e}}/\mathrm{c}{\mathrm{m}}^{-3})\sim 19.5$. However, a lower disk density with normal abundance and ionization could also be possible. From the inner disk radius $R_{\mathrm{in}}=1.67R_{\mathrm{ISCO}}$ and the long-term spin-down rate of $-3.1(2)\times 10^{-15}\mathrm{Hz}{\mathrm{s}}^{-1}$, we constrain the magnetic field of IGR J17498$-$2921 in the range of $(0.9-2.4)\times 10^8$ G.

Published in A&A

References in corpus (25)

• Overview to the Hard X-ray Modulation Telescope (Insight-HXMT) Satellite
• Neutron Stars and the Nuclear Equation of State
• An Empirical Background Model for the NICER X-ray Timing Instrument
• The Medium Energy (ME) X-ray telescope onboard the Insight-HXMT astronomy satellite
• A decade of timing an accretion-powered millisecond pulsar: The continuing spin down and orbital evolution of SAX J1808.4-3658
• High Density Reflection Spectroscopy I. A case study of GX~339-4
• A Hard Look at the Neutron Stars and Accretion Disks in 4U 1636-53, GX 17+2, and 4U 1705-44 with $\text{NuSTAR}$
• Intermediate long X-ray bursts from the ultra-compact binary source SLX 1737-282
• NuSTAR Observations of the Accreting Atolls GX 3+1, 4U 1702-429, 4U 0614+091, and 4U 1746-371
• A Double Outburst from IGR J00291+5934: Implications for Accretion Disk Instability Theory
• Phase-coherent timing of the accreting millisecond pulsar SAX J1748.9-2021
• Timing of the 2008 Outburst of SAX J1808.4-3658 with XMM-Newton: A Stable Orbital Period Derivative over Ten Years
• Reflection Modeling of the Black Hole Binary 4U~1630$-$47: the Disk Density and Returning Radiation
• Spectral and timing properties of the accreting X-ray millisecond pulsar IGR J17511-3057
• The 2015 outburst of the accretion-powered pulsar IGR J00291+5934: INTEGRAL and Swift observations
• Spectral and timing properties of the accreting X-ray millisecond pulsar IGR J17498-2921
• Indications of non-conservative mass-transfer in AMXPs
• The discovery of the 528.6 Hz accreting millisecond X-ray pulsar MAXI J1816-195
• High-energy characteristics of the accretion-powered millisecond pulsar IGR J17591-2342 during its 2018 outburst
• MAXI J1957+032: a new accreting millisecond X-ray pulsar in an ultra-compact binary
• High-density reflection spectroscopy of black hole X-ray binaries in the hard state
• SRG/ART-XC discovery of SRGAJ144459.2-604207: a well-tempered bursting accreting millisecond X-ray pulsar
• The INTEGRAL view of the pulsating hard X-ray sky: from accreting and transitional millisecond pulsars to rotation-powered pulsars and magnetars
• Broadband X-ray timing and spectral characteristics of the accretion-powered millisecond X-ray pulsar MAXI J1816$-$195
• Broad-band X-ray spectra and timing of the accretion-powered millisecond pulsar Swift J1756.9$-$2508 during its 2018 and 2019 outbursts

Cited by in corpus (1)

• Timing and spectral studies of SRGA J144459.2$-$604207 with NICER, Einstein Probe, IXPE, NuSTAR, Insight-HXMT and INTEGRAL during its 2024 outburst