Stellar-mass Black Hole Spin Constraints from Disk Reflection and Continuum Modeling

TL;DR

This study analyzes X-ray spectra of stellar-mass black holes to estimate their spins using reflection and continuum modeling, revealing a range of spin values and potential links to jet activity and black hole formation.

Contribution

It applies combined reflection and continuum spectral modeling to archival data, providing new estimates of black hole spins and exploring their relation to jets and system parameters.

Findings

Black holes with relativistic jets tend to have high spins.

A broad range of spin parameters is observed across the sample.

Some black holes with low spins still exhibit jets.

Abstract

Accretion disk reflection spectra, including broad iron emission lines, bear the imprints of the strong Doppler shifts and gravitational red-shifts close to black holes. The extremity of these shifts depends on the proximity of the innermost stable circular orbit to the black hole, and that orbit is determined by the black hole spin parameter. Modeling relativistic spectral features, then, gives a means of estimating black hole spin. We report on the results of fits made to archival X-ray spectra of stellar-mass black holes and black hole candidates, selected for strong disk reflection features. Following recent work, these spectra were fit with reflection models and disk continuum emission models (where required) in which black hole spin is a free parameter. Although our results must be regarded as preliminary, we find evidence for a broad range of black hole spin parameters in our sample. The black holes with the most relativistic radio jets are found to have high spin parameters, though jets are observed in a black hole with a low spin parameter. For those sources with constrained binary system parameters, we examine the distribution of spin parameters versus black hole mass, binary mass ratio, and orbital period. We discuss the results within the context of black hole creation events, relativistic jet production, and efforts to probe the innermost relativistic regime around black holes.