A Search for Eclipsing Binary Lightcurve Variations among MACHO Project Lightcurves of 3256 Fundamental-Mode RR Lyrae Variables in the Galactic Bulge

TL;DR

This study analyzed lightcurves of over 3000 RR Lyrae stars from the MACHO Project to search for eclipsing binary signatures, finding none, and discussing residual periodic variations likely due to observational aliases.

Contribution

First comprehensive search for eclipsing binary signatures among MACHO RR Lyrae lightcurves, establishing constraints on their occurrence in the Galactic bulge.

Findings

No eclipsing binary signatures detected in the sample.

Residual periodic variations mostly due to period aliases.

Provides a baseline for binary occurrence among RR Lyrae in the bulge.

Abstract

The MACHO Project collected photometry of many RR Lyrae stars from its observations of the Milky Way's bulge. We examined the lightcurves of 3256 stars identified as RRab Lyr variables by \cite{Kund2008}, subtracting an empirical model of the pulsation lightcurve and searching for periodic variation in the residuals. There are no systems which show the brief dips in light characteristic of detached eclipsing binary systems. We discuss the results for objects which show the largest residual periodic modulation, most of which are probably due to aliases of the fundamental period.