Millihertz Quasi-periodic Optical Oscillations in 4U 0614+091

Abstract

We report the discovery of a 1mHz optical quasi-periodic oscillation (QPO) in the candidate ultracompact low-mass X-ray binary 4U 0614+091. The ultra-low frequency QPO has no X-ray counterpart in contemporaneous RXTE/PCA data and is likely a signature of structure in the accretion disk. The QPO can be reasonably fitted with a single sine wave but with a phase jump part way through the observation, indicating that it is not coherent.We also identify a 48 min modulation, approximately consistent with the suggested orbital period of O'Brien (2005) and Shahbaz et al. (2008). If this is indeed orbital, it supports an identification of 4U 0614+091 as an ultra-compact source.

7 pages, 5 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society

References in corpus (6)

• Six new candidate ultracompact X-ray binaries
• Optical spectroscopy of (candidate) ultra-compact X-ray binaries: constraints on the composition of the donor stars
• Spitzer Reveals Infrared Optically-Thin Synchrotron Emission from the Compact Jet of the Neutron Star X-Ray Binary 4U 0614+091
• Time-resolved optical photometry of the ultra-compact binary 4U0614+091
• A relativistically broadened O VIII Lyalpha line in the ultra-compact X-ray binary 4U 0614+091
• Discovery of a broad O VIII Ly alpha line in the ultra-compact X-ray binary 4U 1543-624

Cited by in corpus (5)

• Galactic Ultracompact X-ray Binaries: Disk Stability and Evolution
• UltraCompCAT: a comprehensive Catalogue of Ultra-Compact and Short Orbital Period X-ray Binaries
• Long-term luminosity behavior of 14 ultracompact X-ray binaries
• Polarimetric and spectroscopic optical observations of the ultra-compact X-ray binary 4U 0614+091
• Time-resolved X-Shooter spectra and RXTE light curves of the ultra-compact X-ray binary candidate 4U 0614+091