AGNs in LLAGNs: High resolution radio observations of the Palomar sample

Details AGNs in LLAGNs: High resolution radio observations of the Palomar sample AGNs in LLAGNs: High resolution radio observations of the Palomar sample

Nov 2004

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004iaus..222..461n&link_type=abstract

The Interplay among Black Holes, Stars and ISM in Galactic Nuclei, Proceedings of IAU Symposium, No. 222. Edited by T. Storchi-B

Computer Science

Scientific paper

We present completed results of a high resolution radio imaging survey of the Palomar Spectroscopic Sample of all (˜470) nearby bright northern galaxies. Almost half the Palomar sample's galaxies have nuclei with emission-lines characteristic of AGN but with LHα ≤ 1040 erg s-1. These are referred to as low-luminosity AGNs or LLAGNs. The power source of such LLAGNs has been long debated. High resolution radio surveys of the sample - with the VLA at 15 GHz (150 mas resolution), and the VLBA at 5 GHz (2 mas resolution) - have now revealed a high incidence of pc-scale radio cores with implied brightness temperatures ≳108K, and sub-parsec scale jets. The results support the presence of accreting black holes in ≥50% of all LLAGNs; there is no evidence against all LLAGNs being mini-AGNs. The detected parsec-scale radio nuclei are preferentially found in massive ellipticals and in type 1 nuclei (i.e. nuclei with broad Hα emission). These nuclei follow the usual correlations between radio and emission-line gas properties found in more powerful AGNs. The radio luminosity function (RLF) of Palomar Sample LLAGNs extends three orders of magnitude below, and is continuous with, that of "classical" AGNs. We find marginal evidence for a low-power turnover in the RLF; nevertheless LLAGNs are responsible for a significant fraction of accretion in the local universe. Low accretion rates (≤10-2-10-3 of the Eddington rate) are implied in both advection- and jet-type models. Within the context of jet models, the accretion energy output is dominated by the energy in the observed jets rather than the radiated bolometric luminosity. These jets would be able to dump sufficient energy into the innermost parsecs to significantly slow the accretion inflow. Detailed results can be found in Nagar et al. (2002, 2004) and references therein.

Affiliated with

Also associated with

No associations

Rating

AGNs in LLAGNs: High resolution radio observations of the Palomar sample does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with AGNs in LLAGNs: High resolution radio observations of the Palomar sample, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and AGNs in LLAGNs: High resolution radio observations of the Palomar sample will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1113102