A quantitative explanation of the radio – X-ray correlation in black-hole X-ray binaries

作者：N. D. Kylafis, P. Reig, Αλέξανδρος Τσούρος · 发表于：Astronomy and Astrophysics · 年份：2023 · DOI：10.1051/0004-6361/202346379 · 被引用次数：7 · 研究领域：Astrophysical Phenomena and Observations、Pulsars and Gravitational Waves Research、Relativity and Gravitational Theory

Context. The observed correlation between the radio and X-ray fluxes in the hard state of black-hole X-ray binaries (BHXRBs) has been in existence for over two decades. It is currently accepted that the hard X-rays in BHXRBs come from Comptonization in the corona and the radio emission from the relativistic jet (Lorentz γ ≫ 1), which is a narrow structure of a few R g = GM/c 2 at its base. The jet and the corona, however, are separate entities with hardly any communication between them, apart from the fact that both are fed from the accreting matter. Aims. It is also widely accepted that the accretion flow around the black holes in BHXRBs consists of a thin outer disk and a hot inner flow. From this hot inner flow, which has a positive Bernoulli integral, an outflow must emanate in the hard and hard-intermediate states of the source. By considering Compton up-scattering of soft disk photons in the outflow (i.e., in the outflowing “corona”, which is a wider structure of tens to hundreds of R g at its base) as the mechanism that produces the hard X-ray spectrum, we have been able to quantitatively explain a number of observed correlations. Here, we investigate whether this outflowing corona can also explain the observed radio – X-ray correlation. We remark that the outflowing corona (wide, with a low Lorentz γ ) is completely separate from the relativistic jet (narrow, with a high Lorentz γ ). The two may coexist, with the jet at the rotation axis and the corona around it. Meth...