X-ray irradiation of the stellar wind in HMXBs with B supergiants: Implications for ULXs

0556343 - ASÚ 2023 RIV FR eng J - Článek v odborném periodiku
Krtička, J. - Kubát, Jiří - Krtičková, I.
X-ray irradiation of the stellar wind in HMXBs with B supergiants: Implications for ULXs.
Astronomy & Astrophysics. Roč. 659, March (2022), č. článku A117. ISSN 0004-6361. E-ISSN 1432-0746
Institucionální podpora: RVO:67985815
Klíčová slova: radiation-driven winds * blanketed model atmospheres * hot luminous stars
Obor OECD: Astronomy (including astrophysics,space science)
Impakt faktor: 6.5, rok: 2022
Způsob publikování: Open access s časovým embargem
https://doi.org/10.1051/0004-6361/202142502

We study the effect of X-ray ionization on the stellar wind of B supergiants. We determine the binary parameters for which the X-ray irradiation significantly influences the stellar wind. This can be conveniently studied in diagrams that plot the optical depth parameter versus the X-ray luminosity. For low optical depths or for high X-ray luminosities, X-ray ionization leads to a disruption in the wind aimed toward the X-ray source. Observational parameters of high-mass X-ray binaries with B-supergiant components appear outside the wind disruption zone. The X-ray feedback determines the resulting X-ray luminosity. We recognize two states with a different level of feedback. For low X-ray luminosities, ionization is weak, and the wind is not disrupted by X-rays and flows at large velocities, consequently the accretion rate is relatively low. On the other hand, for high X-ray luminosities, the X-ray ionization disrupts the flow braking the acceleration, the wind velocity is low, and the accretion rate becomes high. These effects determine the X-ray luminosity of individual binaries. Accounting for the X-ray feedback, estimated X-ray luminosities reasonably agree with observational values. We study the effect of small-scale wind inhomogeneities (clumping), showing that clumping weakens the effect of X-ray ionization by increasing recombination and the mass-loss rate. This effect is particularly important in the region of the so-called bistability jump. We show that ultraluminous X-ray binaries with LX less than or similar to 10(40) erg s(-1) may be powered by accretion of a B-supergiant wind on a massive black hole.
Trvalý link: http://hdl.handle.net/11104/0330920