ON THE RADIO AND NEAR-INFRARED JET OF PKS 2155–304 AND ITS CLOSE ENVIRONMENT

摘要

PKS 2155–304 is one of the brightest BL Lac objects in the sky and a very well-studied target from radio to TeV bands. We report on high-resolution (~012) direct imaging of the field of PKS 2155–304 using adaptive optics near-IR (NIR) observations in the J and Ks bands obtained with the ESO Multi-Conjugate Adaptive Optics Demonstrator on the Very Large Telescope. These data are complemented with archival Very Large Array images at various frequencies to investigate the properties of the close environment of the source. We characterize the faint galaxies that form the poor group associated with the target. No radio emission is present for these galaxies, while an old radio jet at ~20?kpc from the nucleus of PKS 2155–304 and a jet-like structure of ~2?kpc (~1'') in the eastern direction are revealed. No counterparts of these radio jets are found in the NIR or in archival Chandra observations.