X-Rays from Cepheus A East and West

Abstract

We report the discovery of X-rays from both components of Cepheus A, East and West, with the XMM-Newton observatory. HH 168 joins the ranks of other energetic Herbig-Haro objects that are sources of T>=10⁶ K X-ray emission. The effective temperature of HH 168 is T=5.8^+3.5_-2.3×10⁶ K, and its unabsorbed luminosity is 1.1×10²⁹ ergs s^-1, making it hotter and less luminous than other representatives of its class. We also detect prominent X-ray emission from the complex of compact radio sources believed to be the power sources for Cep A. We call this source HWX, and it is distinguished by its hard X-ray spectrum, T=1.2^+1.2_-0.5×10⁸ K, and its complex spatial distribution. It may arise from one or more protostars associated with the radio complex, the outflows, or a combination of the two. We detect 102 X-ray sources, many presumed to be pre-main-sequence stars on the basis of the reddening of their optical and IR counterparts.