Reapproaching the Spin Estimate of GX 339-4

TL;DR

This study reanalyzed GX 339-4's X-ray data using advanced models, confirming it has a near-maximal spin and exploring its relation to jet power, with implications for black hole properties.

Contribution

It provides a more accurate spin measurement of GX 339-4 using self-consistent reflection modeling across multiple states.

Findings

GX 339-4 has a spin parameter >0.97.

The inclination angle is 36 ± 4 degrees.

No correlation found between spin and jet power.

Abstract

We systematically reanalyze two previous observations of the black hole (BH) GX 339-4 in the very high and intermediate state taken with $\emph{XMM-Newton}$ and $\emph{Suzaku}$. We utilize up-to-date data reduction procedures and implement the recently developed, self-consistent model for X-ray reflection and relativistic ray tracing, {\sc relxill}. In the very high and intermediate state, the rate of accretion is high and thus the disk remains close to the innermost stable circular orbit (ISCO). We require a common spin parameter and inclination when fitting the two observations since these parameters should remain constant across all states. This allows for the most accurate determination of the spin parameter of this galactic black hole binary from fitting the Fe K$\alpha$ emission line and provides a chance to test previous estimates. We find GX 339-4 to be consistent with a near maximally spinning black hole with a spin parameter $a_{*}$ $>0.97$ with an inclination of $36 \pm 4$ degrees. This spin value is consistent with previous high estimates for this object. Further, if the inner disk is aligned with the binary inclination, this modest inclination returns a high black hole mass, but they need not be aligned. Additionally, we explore how the spin is correlated with the power of the jet emitted but find no correlation between the two.