Detection of a 23.6 min periodic modulation in the optical counterpart of 3XMMJ051034.6--670353

TL;DR

This study reports the detection of a 23.6-minute periodic modulation in the optical counterpart of the X-ray source 3XMMJ051034.6--670353, using high-speed photometry and spectroscopy, suggesting a possible ultra-compact binary system.

Contribution

First optical detection of a 23.6-minute periodicity in 3XMMJ051034.6--670353, with spectral analysis indicating no strong emission lines and implications for binary mass distribution.

Findings

Optical and X-ray periodicities are consistent.

No strong emission lines detected in optical spectrum.

Possible stable direct impact accretion in the binary system.

Abstract

We present high speed optical photometric observations made using the NTT and ULTRACAM of the optical counterpart of 3XMMJ051034.6--670353, which was recently identified as an X-ray source showing a modulation on a period of 23.6 min. Although the optical counterpart is faint (g=21.4), we find that the u'g'r' light curves show a periodic modulation on a period which is consistent with the X-ray period. We also obtained three low resolution spectra of 3XMMJ051034.6--670353 using the Gemini South Telescope and GMOS. There is no evidence for strong emission lines in the optical spectrum of 3XMMJ051034.6--670353. We compare and contrast the optical and X-ray observations of 3XMMJ051034.6--670353 with the ultra compact binaries HM Cnc and V407 Vul. We find we can identify a distribution of binary masses in which stable direct impact accretion can occur.