The jet of the BL Lac object PKS 0521 -365 in the near-IR : MAD adaptive optics observations
| Autor: | Falomo, R., Pian, E., Treves, A., Giovannini, G., Venturi, T., Moretti, A., Arcidiacono, C., Farinato, J., Ragazzoni, R., Diolaiti, E., Lombini, M., Tavecchio, F., Brast, R., Marchetti, E., Tordo, S. |
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| Rok vydání: | 2009 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/200912077 |
| Popis: | BL Lac objects are low--power active nuclei exhibiting a variety of peculiar properties that are caused by the presence of a relativistic jet and orientation effects. We present here 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. The observations were obtained in Ks--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 R band and by a re-analysis of VLA radio maps. 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. The bright red object (red-tip), 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. 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. Comment: accepted for publication in Astronomy and Astrophysics 9 pages. A & A 2009, in press |
| Databáze: | arXiv |
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