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dc.contributor.author | Sidoli L. | |
dc.contributor.author | Postnov K. | |
dc.contributor.author | Oskinova L. | |
dc.contributor.author | Esposito P. | |
dc.contributor.author | De Luca A. | |
dc.contributor.author | Marelli M. | |
dc.contributor.author | Salvaterra R. | |
dc.date.accessioned | 2022-02-09T20:30:35Z | |
dc.date.available | 2022-02-09T20:30:35Z | |
dc.date.issued | 2021 | |
dc.identifier.issn | 0004-6361 | |
dc.identifier.uri | https://dspace.kpfu.ru/xmlui/handle/net/168637 | |
dc.description.abstract | We report on the results of an XMM-Newton observation of the supergiant fast X-ray transient (SFXT) IGR J08408-4503 performed in June 2020. The source is composed of a compact object (likely a neutron star) orbiting around an O8.5Ib-II(f)p star, LM Vel. The X-ray light curve shows a very low level of emission, punctuated by a single, faint flare. We analysed spectra measured during the flare and during quiescence. The quiescent state shows a continuum spectrum that is well deconvolved to three spectral models: two components are from a collisionally ionized plasma (with temperatures of kT1 = 0.24 keV and kT2 = 0.76 keV), together with a power-law model (photon index, Γ, of ∼2.55), dominating above ∼2 keV. The X-ray flux emitted at this lowest level is 3.2 × 10-13 erg cm-2 s-1 (0.5-10 keV, corrected for the interstellar absorption), implying an X-ray luminosity of 1.85 × 1032 erg s-1 (at 2.2 kpc). The two-temperature collisionally ionized plasma is intrinsic to the stellar wind of the donor star, while the power-law can be interpreted as emission due to residual, low-level accretion onto the compact object. The X-ray luminosity contributed by the power-law component only, in the lowest state, is (4.8 ± 1.4)×1031 erg s-1, which is the lowest quiescent luminosity detected from the compact object in an SFXT. Thanks to this very faint X-ray state caught by XMM-Newton, X-ray emission from the wind of the donor star LM Vel could be well-established and studied in detail for the first time, along with a very low level of accretion onto the compact object. The residual accretion rate onto the compact object in IGR J08408-4503 can be interpreted as the Bohm diffusion of (possibly magnetized) plasma entering the neutron star magnetosphere at low Bondi capture rates from the supergiant donor wind at the quasi-spherical, radiation-driven settling accretion stage. | |
dc.relation.ispartofseries | Astronomy and Astrophysics | |
dc.subject | Stars: individual: HD 74194 | |
dc.subject | Stars: individual: IGR J08408-4503 | |
dc.subject | Stars: individual: LM Vel | |
dc.subject | Stars: neutron | |
dc.subject | Supergiants | |
dc.subject | X-rays: binaries | |
dc.title | Detecting the intrinsic X-ray emission from the O-type donor star and the residual accretion in a supergiant fast X-ray transient in its faintest state | |
dc.type | Article | |
dc.relation.ispartofseries-volume | 654 | |
dc.collection | Публикации сотрудников КФУ | |
dc.source.id | SCOPUS00046361-2021-654-SID85118230782 |