# The Low-Spin Black Hole in LMC X-3

## TL;DR

This paper measures the low spin of the black hole in LMC X-3 using a large set of X-ray spectra and a new dynamical model, accounting for systematic errors and exploring spin-spectrum correlations.

## Contribution

It introduces a refined dynamical model and applies the continuum-fitting method to over a thousand spectra to estimate the black hole's spin with comprehensive uncertainty analysis.

## Key findings

- Black hole spin in LMC X-3 is approximately 0.21 with uncertainties.
- Systematic errors significantly influence spin measurement accuracy.
- Evidence suggests a correlation between black hole spin and X-ray spectrum complexity.

## Abstract

Building upon a new dynamical model for the X-ray binary LMC X-3, we measure the spin of its black hole primary via the continuum-fitting method. We consider over one thousand thermal-state RXTE X-ray spectra of LMC X-3. Using a large subset of these spectra, we constrain the spin parameter of the black hole to be spin = 0.21(+0.18,-0.22), 90% confidence. Our estimate of the uncertainty in spin takes into account a wide range of systematic errors. We discuss evidence for a correlation between a black hole's spin and the complexity of its X-ray spectrum.