2002/10/01 by R. C. Vermeulen, E. Ros, K. I. Kellermann +4 · 6 citations
Physics and Astronomy · #Absorption (acoustics) #Absorption spectroscopy #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Centaurus A #Galaxy #Gamma-ray bursts and supernovae #Jet (fluid) #Optics #Physics #Radio galaxy #Sky #Spectral line #Very-long-baseline interferometry #astro-ph
paper · pdf · doi:10.1071/as02037
published in Publications of the Astronomical Society of Australia 20(1), 65-68 (Cambridge University Press) · 6 pages, 3 figures, prepared in LaTeX. Revised version, will appear in Publications of the Astronomical Society of Australia, as part of the proceedings of the 3rd GPS/CSS workshop, ed. T. Tzioumis, W. de Vries, I. Snellen, A. Koekemoer
arxiv created 2002/10/01 · openalex publication_date 2003/01/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract This is a paper on young jet material in a frustratingly complex environment. NGC 1052 has a compact, flat or GHz peaked spectrum radio nucleus consisting of bi-symmetric jets, oriented close to the plane of the sky. Many features on both sides move away at υ app ˜0.26 c ( H 0 = 65 km s −1 Mpc −1 ). VLBI at seven frequencies shows a wide range of spectral shapes and brightness temperatures; there is clearly free–free absorption, probably together with synchrotron self-absorption, on both sides of the core. The absorbing structure is likely to be geometrically thick and oriented roughly orthogonal to the jets, but it is patchy. H I VLBI shows atomic gas in front of the approaching as well as the receding jet. There appear to be three velocity systems, at least two of which are local to the AGN environment. The ‘high velocity system’, 125–200 km s −1 redward of systemic, seems restricted to a shell 1–2 pc away from the core. Closer to the centre, this gas might be largely ionised; it could cause the free–free absorption. WSRT spectroscopy shows 1667 and 1665 MHz OH absorption over a wide velocity range. OH and H I profile similarity suggests co-location of molecular and atomic ‘high velocity’ gas; the connection to H 2 O masing gas is unclear. Further, at ‘high velocity’ we detected the OH 1612 MHz satellite line in absorption and the 1720 MHz line in emission, with complementary strengths.