X‐Ray Properties of the Gigahertz Peaked and Compact Steep Spectrum Sources

Abstract

We present Chandra X-ray Observatory observations of gigahertz peaked-spectrum (GPS) and compact steep spectrum (CSS) radio sources. The Chandra sample contains 13 quasars and 3 galaxies, with measured 2-10 keV X-ray luminosities within 1042-1046 erg s−1. We detect all of the sources, five of which are observed in X-rays for the first time. We study the X-ray spectral properties of the sample. The measured absorption columns in the quasars are different from those in the galaxies in that the quasars show no absorption (with limits ~1021 cm−2), while the galaxies have large absorption columns (>1022 cm−2) consistent with previous findings. The median photon index of the sources with a high signal-to-noise ratio is Γ = 1.84 ± 0.24, which is larger than the typical index of radio-loud quasars. The arcsec resolution of the Chandra telescope allows us to investigate extended X-ray emission and to look for diffuse components and X-ray jets. We found X-ray jets in two quasars (PKS 1127–145 and B2 0738+32), and an X-ray cluster surrounding a CSS quasar (3C 186; z = 1.1). We detected a possible binary structure in galaxy 0941–080 and an extended diffuse emission in galaxy PKS B1345+125. We discuss our results in the context of X-ray emission processes and radio source evolution. We conclude that the X-ray emission in these sources is most likely unrelated to a relativistic jet, although the sources' radio loudness may suggest a high radiative efficiency for the jet power in these sources.