The nature of ultraluminous X-ray sources in NGC 4565

We report the optical identifications of two X-ray-luminous point sources in the spiral galaxy NGC 4565 based on archive data of Chandra and the Hubble Space Telescope. The central X-ray point source, RX J1236.3+2559, is found to be the nucleus of NGC 4565 with an X-ray luminosity of L-X approximate to 4.3 x 10(39) ergs s(-1). We show that its multiband properties are consistent with its being a low-luminosity active galactic nucleus. A faint optical counterpart with B approximate to 25.1 and I approximate to 24.0 was identified for the off-nucleus X-ray point source, RX J1236.2+2558. Its extinction-corrected B magnitude is estimated to be 24.5. The X-ray to optical flux ratio (f(X)/f(B)) is about 540. From the optical and X-ray properties, we argue that RX J1236.2+2558 is an ultraluminous X-ray compact source with L-X approximate to 6.5 x 10(39) ergs s(-1). The source is probably located in a faint globular cluster at the outer edge of NGC 4565's bulge.