Spectral and timing properties of the accreting millisecond X-ray pulsar IGR J17498−2921 during its 2023 outburst
We present a comprehensive study of the spectral properties of the accreting millisecond X-ray pulsar IGR J17498−2921 during its 2023 outburst. Similar to other accreting millisecond X-ray pulsars, the broadband spectral emission observed quasi-simultaneously by NICER and NuSTAR is well described by an absorbed Comptonized emission with an electron temperature of ∼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 ∼21 R g from the source, near the Keplerian corotation radius. From the high-cadence monitoring data obtained with NICER, we observed 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 ∼–0.25 cycle jump in the pulse phase, which occurs immediately following an X-ray flux flare and a drop in the pulse amplitude below the 3 σ detection threshold. We also report on the non-detection of optical pulsations with TNG/SiFAP2 from the highly absorbed optical counterpart.
Authors
- F. Leone (ORCID: https://orcid.org/0000-0001-7626-3788)
- A. Ghedina
- A. Marino (ORCID: https://orcid.org/0000-0001-5674-4664)
- Riccardo La Placa (ORCID: https://orcid.org/0000-0003-2810-2394)
- A. Papitto
- T. Di Salvo (ORCID: https://orcid.org/0000-0002-3220-6375)
- A. Sanna
- F. Coti Zelati
- M. Cecconi
- G. Illiano (ORCID: https://orcid.org/0000-0003-4795-7072)
- A. Miraval Zanon (ORCID: https://orcid.org/0000-0002-0943-4484)
- Tod E. Strohmayer (ORCID: https://orcid.org/0000-0001-7681-5845)
- C. Malacaria
- Filippo Ambrosino (ORCID: https://orcid.org/0000-0001-7915-996X)
- Caterina Ballocco
- M. Gonzales
Institutions
- University of Rome Tor Vergata (IT)
- Goddard Space Flight Center (US)
- Institute of Space Sciences (ES)
- University of Cagliari (IT)
- Astronomical Observatory of Rome (IT)
- Brera Astronomical Observatory (IT)
- Institut d'Estudis Espacials de Catalunya (ES)
- Joint Space Science Institute (US)
- Osservatorio Astrofisico di Catania (IT)
- Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari (IT)
- Telescopio Nazionale Galileo (ES)
- Deleted Institution
- Sapienza University of Rome (IT)
- University of Palermo (IT)
Publication Details
- Journal
- Astronomy and Astrophysics
- Published
- 2024-10-07
- DOI
- https://doi.org/10.1051/0004-6361/202451703
- Citations
- 3
- Primary Topic
- Astrophysical Phenomena and Observations
- Type
- article
- Field-Weighted Citation Impact
- 0.99
Funders
- National Aeronautics and Space Administration
- California Institute of Technology
- European Commission
- Istituto Nazionale di Astrofisica
- Jet Propulsion Laboratory