Discovery of X-rays from class 0 protostar candidates in OMC-3

We have observed the Orion Molecular Clouds 2 and 3 (OMC-2 and OMC-3) with the Chandra X-Ray Observatory (CXO). The northern part of OMC-3 is found to be particularly rich in new X-ray features; four hard X-ray sources are lo cated in and along the filament of cloud cores. Two sources coincide positi onally with the submillimeter-millimeter dust condensations of MMS 2 and 3 or an outflow radio source VLA 1, which are in a very early phase of star f ormation. The X-ray spectra of these sources show an absorption column of ( 1-3) x 10(23) H cm(-2). Assuming a moderate temperature plasma, the X-ray l uminosity in the 0.5-10 keV band is estimated to be similar to 10(30) ergs s(-1) at a distance of 450 pc. From the large absorption, positional coinci dence, and moderate luminosity, we infer that the hard X-rays are coming fr om very young stellar objects embedded in the molecular cloud cores. We fou nd another hard X-ray source near the edge of the dust filament. The extrem ely high absorption of 3 x 10(23) H cm(-2) indicates that the source must b e surrounded by dense gas, suggesting that it is either a young stellar obj ect in an early accretion phase or a Type II AGN (e.g., a Seyfert 2), altho ugh no counterpart is found at any other wavelength. In contrast to the har d X-ray sources, soft X-ray sources are found spread around the dust filame nts, most of which are identified with IR sources in the T. Tauri phase.