quantitative determination of the AGN content in local ULIRGs through L-band spectroscopy
Abstract
We present a quantitative estimate of the relative AGN/starburst content in a sample of 59 nearby (z<0.15) infrared bright ULIRGs taken from the 1 Jy sample, based on infrared L-band (3-4 micron) spectra. By using diagnostic diagrams and a simple deconvolution model, we show that at least 60% of local ULIRGs contain an active nucleus, but the AGN contribution to the bolometric luminosity is relevant only in ~15-20% of the sources. Overall, ULIRGs appear to be powered by the starburst process, responsible for >85% of the observed infrared luminosity. The subsample of sources optically classified as LINERs (31 objects) shows a similar AGN/starburst distribution as the whole sample, indicating a composite nature for this class of objects. We also show that a few ULIRGs, optically classified as starbursts, have L-band spectral features suggesting the presence of a buried AGN.
Keywords
Cite
@article{arxiv.0908.4544,
title = {quantitative determination of the AGN content in local ULIRGs through L-band spectroscopy},
author = {G. Risaliti and M. Imanishi and E. Sani},
journal= {arXiv preprint arXiv:0908.4544},
year = {2015}
}
Comments
8 Pages, 5 figures. Accepted for publication in MNRAS