Supplementary Information for "A 15.65 solar mass black hole in an eclipsing binary in the nearby spiral galaxy Messier 33"

TL;DR

This supplementary information details spectral analysis, distance estimation, wind modeling, eclipse measurement, and ellipsoidal modeling for a black hole in M33, supporting the main study of a 15.65 solar mass black hole in an eclipsing binary.

Contribution

Provides detailed methodological and analytical support for the main paper, including spectral extraction, wind modeling, and eclipse analysis.

Findings

Refined spectral extraction techniques for crowded fields.

Measurement of the true eclipse width Theta.

Discussion of the distance to M33 and its impact on mass estimates.

Abstract

This Supplementary Information provides details about the spectral extraction (crowding issues and the removal of nebular lines), a discussion about the distance to M33, a model for the O-star wind and the measurement of the true photospheric X-ray eclipse width Theta, and details about ellipsoidal modelling. It also contains five related figures, one related table, and additional references.