A disc corona–jet model for the radio/X-ray correlation in black hole X-ray binaries

• Published in: Monthly notices of the Royal Astronomical Society 2015-04, Vol.448 (2), p.1099-1106
• Main Authors: Qiao, Erlin, Liu, B. F.
• Format: Article
• Language: English
• Subjects: Accretion disks; Binary stars; Black holes; Black holes (astronomy); Corona; Correlation; Correlation analysis; Double stars; Joining; Mathematical models; Radio; X-ray astronomy; X-ray stars; X-rays
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stv085

The observed tight radio/X-ray correlation in the low spectral state of some black hole X-ray binaries implies the strong coupling of the accretion and jet. The correlation of $L_{\rm R} \propto L_{\rm X}^{\sim 0.5\hbox{-}0.7}$ was well explained by the coupling of a radiatively inefficient accretion flow and a jet. Recently, however, a growing number of sources show more complicated radio/X-ray correlations, e.g. $L_{\rm R} \propto L_{\rm X}^{\sim 1.4}$ for L X/L Edd ≳ 10−3, which is suggested to be explained by the coupling of a radiatively efficient accretion flow and a jet. In this work, we interpret the deviation from the initial radio/X-ray correlation for L X/L Edd ≳ 10−3 with a detailed disc corona–jet model. In this model, the disc and corona are radiatively and dynamically coupled. Assuming a fraction of the matter in the accretion flow, $\eta \equiv \dot{M}_{\rm jet}/\dot{M}$ , is ejected to form the jet, we can calculate the emergent spectrum of the disc corona–jet system. We calculate L R and L X at different $\dot{M}$ , adjusting η to fit the observed radio/X-ray correlation of the black hole X-ray transient H1743−322 for L X/L Edd > 10−3. It is found that always the X-ray emission is dominated by the disc corona and the radio emission is dominated by the jet. We noted that the value of η for the deviated radio/X-ray correlation for L X/L Edd > 10−3 is systematically less than that of the case for L X/L Edd