Correlations between radio and bolometric fluxes in GX 339-4 and H1743-322

TL;DR

This study investigates the relationship between radio and broad-band X-ray fluxes in black-hole binaries GX 339-4 and H1743-322, revealing different correlation behaviors during outburst rise and decline, suggesting jet hysteresis effects.

Contribution

It provides the first analysis of radio and bolometric X-ray flux correlations, highlighting differences from narrow-band X-ray studies and evidence of jet hysteresis in black-hole binary evolution.

Findings

Power-law indices differ from narrow-band X-ray correlations.

Radio/bolometric flux correlations vary between outburst rise and decline.

H1743-322 shows different correlation behavior compared to GX 339-4 during decline.

Abstract

Compact radio jets are ubiquitous in stellar-mass black-hole binaries in their hard spectral state. Empirical relations between the radio and narrow-band X-ray fluxes have been used to understand the connection between their accretion discs and jets. However, a narrow-band (e.g., 1--10 or 3--9 keV) X-ray flux can be a poor proxy for either the bolometric luminosity or the mass accretion rate. Here, we study correlations between the radio and unabsorbed broad-band X-ray fluxes, the latter providing good estimates of the bolometric flux. We consider GX 339--4, the benchmark object for the main branch of the correlation, and H1743--322, the first source found to be an outlier of the correlation. The obtained power-law dependencies of the radio flux on the bolometric flux have significantly different indices from those found for the narrow X-ray bands. Also, the radio/bolometric flux correlations for the rise of the outbursts are found to be significantly different from those for the outburst decline. This points to a possible existence of a jet hysteresis in the radio/X-ray source evolution, in addition to that seen in the hardness/flux diagram of low-mass X-ray binaries. The correlation during the rise of the outbursts is similar for both GX 339--4 and H1743--322. The correlation for the decline of the outbursts for H1743--322 lies below that of GX 339--4 at intermediate X-ray fluxes, whereas it approaches the standard correlation at lower X-ray luminosities. We also compare these correlations to those for the high-mass X-ray binaries Cyg X-1 and Cyg X-3.