2009/05/27 by R. Falomo, E. Pian, A. Treves +14
Physics and Astronomy · #Active galactic nucleus #Adaptive optics #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #BL Lac object #Galaxies: Formation, Evolution, Phenomena #Jet (fluid) #Radio galaxy #Synchrotron #Synchrotron radiation #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1051/0004-6361/200912077
accepted for publication in Astronomy and Astrophysics 9 pages. A & A 2009, in press
openalex publication_date 2009/05/27 · arxiv created 2009/06/05 · arxiv updated 2015/05/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
<i>Context. <i/>BL Lac objects are low-power active nuclei exhibiting a variety of peculiar properties caused by the presence of a relativistic jet and orientation effects. <i>Aims. <i/>We present adaptive optics near-IR images at high spatial resolution of the nearby BL Lac object PKS 0521-365, which is known to display a prominent jet both at radio and optical frequencies.<i>Methods. <i/>The observations were obtained in <i>K<i/>s-band using the ESO multi-conjugated adaptive optics demonstrator at the Very Large Telescope. This allowed us to obtain images with 0.1 arcsec effective resolution. We performed a detailed analysis of the jet and its related features from the near-IR images, and combined them with images previously obtained with HST in the <i>R<i/> band and by a re-analysis of VLA radio maps. <i>Results. <i/>We find a remarkable similarity in the structure of the jet at radio, near-IR, and optical wavelengths. The broad–band emission of the jet knots is dominated by synchrotron radiation, while the nucleus also exhibits a significant inverse Compton component. We discovered the near-IR counterpart of the radio hotspot and found that the near-IR flux is consistent with being a synchrotron emission from radio to X-ray wavelengths. The bright red object (<i>red-tip<i/>), detached but well aligned with the jet, is well resolved in the near-IR and has a linear light profile. Since it has no radio counterpart, we propose that it is a background galaxy not associated with the jet. <i>Conclusions. <i/>The new adaptive optics near-IR images and previous observations at other frequencies allow us to study the complex environment around the remarkable BL Lac object PKS 0521-365. These data exemplify the capabilities of multi conjugate adaptive optics observations of extragalactic extended sources.