Disc and wind in black hole X-ray binary MAXI J1820+070 observed through polarized light during its 2018 outburst

Ilia A. Kosenkov, Alexandra Veledina, Andrei V. Berdyugin, Vadim Kravtsov, Vilppu Piirola, Svetlana V. Berdyugina, Takeshi Sakanoi, Masato Kagitani, Juri Poutanen

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

We describe the first complete polarimetric data set of the entire outburst of a low-mass black hole X-ray binary system and discuss the constraints for geometry and radiative mechanisms it imposes. During the decaying hard state, when the optical flux is dominated by the non-thermal component, the observed polarization is consistent with the interstellar values in all filters. During the soft state, the intrinsic polarization of the source is small, ∼0.15 per cent in B and V filters, and is likely produced in the irradiated disc. A much higher polarization, reaching ∼0.5 per cent in V and R filters, at a position angle of ∼25a observed in the rising hard state coincides in time with the detection of winds in the system. This angle coincides with the position angle of the jet. The detected optical polarization is best explained by scattering of the non-thermal (hot flow or jet base) radiation in an equatorial wind.

Original languageEnglish
Pages (from-to)L96-L100
JournalMonthly Notices of the Royal Astronomical Society: Letters
Volume496
Issue number1
DOIs
Publication statusPublished - 2020 May 22

Keywords

  • X-rays: binaries
  • polarization
  • stars: black holes
  • stars: individual: MAXI J1820+070

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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