A Chandra Census of C2D YSOS: Evolution of X-ray Emission

We present an analytical study of a large sample of ~109 young stellar objects in the X-ray. Our objects were detected in X-ray independent of age. Unexpectedly, the X-ray energy is somewhat correlated with the ages. It decreases with time and with column density, while it should increase. We conclude that the youngest protostars, Class 0/I, emit X-rays in the 1-8 keV band. The deeply embedded sources with the strongest accretion activity are detected in the hard-band (> 2keV) only. Due to extinction, their soft X-rays are not detected. To explain the decline in energy, we suggest that within a timescale of few Myrs the corona cools down via the accretion material.