An X-ray study of the dwarf nova candidate OGLE-BLG-DN-0064 using Chandra data

OGLE-BLG-DN-0064 (hereafter, OGLE-64) has been identified as a possible dwarf nova candidate due to the optical outburst activity recorded by the Optical Gravitational Lensing Experiment (OGLE) survey. We study the X-ray properties of OGLE-64 using the Chandra archival data. OGLE-64 shows an X-ray luminosity of $L_X \approx 1.5 \times 10^{32}$ erg/s in the 0.5–7 keV energy band and a high ratio of X-ray flux to optical flux $F_X/F_{\rm opt} \approx 1.5$. We found no significant optical and X-ray periodicity with the timing analyses. The X-ray spectrum of OGLE-64 can be approximated by a power-law model with a photon index of $\Gamma \approx 1.9$ and an optically thin plasma model with a temperature of $kT \approx 6.4$ keV. The isobaric cooling flow model gives an accretion rate in the system of about $\dot{M}_{\rm acc} \approx 5.4 \times 10^{-11}$ $M_\odot$/yr and the white dwarf mass of $M_{\rm WD} \approx 0.8$ $M_\odot$. The X-ray properties and the optical outburst activity suggest that OGLE-64 is a dwarf nova.