The Distance, Inclination, and Spin of the Black Hole Microquasar H1743-322

TL;DR

This study measures the distance, inclination, and spin of the black hole in microquasar H1743-322 using jet trajectories and spectral fitting, finding a moderate spin and ruling out extreme values.

Contribution

It provides the first combined measurement of jet kinematics and black hole spin for H1743-322, improving understanding of black hole properties in microquasars.

Findings

Distance to H1743-322 is 8.5 ± 0.8 kpc.

Inclination angle of jets is 75 ± 3 degrees.

Black hole spin parameter a* is between -0.3 and 0.7 at 90% confidence.

Abstract

During its 2003 outburst, the black-hole X-ray transient H1743-322 produced two-sided radio and X-ray jets. Applying a simple and symmetric kinematic model to the trajectories of these jets, we determine the source distance, 8.5 \pm 0.8 kpc, and the inclination angle of the jets, 75 \pm 3 degrees. Using these values, we estimate the spin of the black hole by fitting its RXTE spectra, obtained during the 2003 outburst, to a standard relativistic accretion-disk model. For its spin, we find a*=0.2 \pm 0.3 (68% limits); -0.3 < a* < 0.7 at 90% confidence. We rule strongly against an extreme value of spin: a* < 0.92 at 99.7% confidence. H1743-322 is the third known microquasar (after A0620-00 and XTE J1550-564) that displays large-scale ballistic jets and has a moderate value of spin. Our result, which depends on an empirical distribution of black hole masses, takes into account all known sources of measurement error.