Issue |
A&A
Volume 689, September 2024
|
|
---|---|---|
Article Number | A172 | |
Number of page(s) | 7 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361/202449228 | |
Published online | 12 September 2024 |
XMM-Newton and NuSTAR discovery of a likely IP candidate XMMU J173029.8–330920 in the Galactic disc
1
INAF – Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy
2
Max-Planck-Institut für extraterrestrische Physik, Gießenbachstraße 1, 85748 Garching, Germany
3
Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA
4
School of Astronomy and Space Science, Nanjing University, Nanjing 210046, China
5
Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans s/n, E-08193 Barcelona, Spain
6
Institut d’Estudis Espacials de Catalunya (IEEC), Carrer Gran Capità 2–4, 08034 Barcelona, Spain
Received:
13
January
2024
Accepted:
3
July
2024
Aims. We aim to characterise the population of low-luminosity X-ray sources in the Galactic plane by studying their X-ray spectra and periodic signals in the light curves.
Methods. We are performing an X-ray survey of the Galactic disc using XMM-Newton, and the source XMMU J173029.8–330920 was serendipitously discovered in our campaign. We performed a follow-up observation of the source using our pre-approved NuSTAR target of opportunity time. We used various phenomenological models in XSPEC for the X-ray spectral modelling. We also computed the Lomb-Scargle periodogram to search for X-ray periodicity. A Monte Carlo method was used to simulate 1000 artificial light curves in order to estimate the significance of the detected period. We also searched for X-ray, optical, and infrared counterparts of the source in various catalogues.
Results. The spectral modelling indicates the presence of an intervening cloud with NH ∼ (1.5 − 2.3)×1023 cm−2 that partially absorbs the incoming X-ray photons. The X-ray spectra are best fit by a model representing emission from a collisionally ionised diffuse gas with a plasma temperature of kT = 26−5+11 keV. Furthermore, an Fe Kα line at 6.47−0.06+0.13 keV was detected with an equivalent width of the line of 312 ± 104 eV. We discovered a coherent pulsation with a period of 521.7 ± 0.8 s. The 3–10 keV pulsed fraction of the source is around ∼50–60%.
Conclusions. The hard X-ray emission with plasma temperature kT = 26−5+11 keV, iron Kα emission at 6.4 keV, and a periodic behaviour of 521.7 ± 0.8 s suggest XMMU J173029.8–33092 to be an intermediate polar. We estimated the mass of the central white dwarf to be 0.94 − 1.4 M⊙ by assuming a distance to the source of ∼1.4 − 5 kpc.
Key words: binaries: close / novae / cataclysmic variables / white dwarfs / Galaxy: center / Galaxy: disk
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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