A quantitative determination of the AGN content in local ULIRGs through L-band spectroscopy

作者：Risaliti G^*; Imanishi M; Sani E

来源：Monthly Notices of the Royal Astronomical Society, 2010, 401(1): 197-203.

DOI：10.1111/j.1365-2966.2009.15622.x

• galaxies: active
• galaxies: starburst
• infrared: galaxies

We present a quantitative estimate of the relative active galactic nucleus (AGN)/starburst content in a sample of 59 nearby (z < 0.15) infrared bright ultraluminous infrared galaxies (ULIRGs) taken from the 1-Jy sample, based on infrared L-band (3-4 mu m) spectra. By using diagnostic diagrams and a simple deconvolution model, we show that at least 60 per cent of local ULIRGs contain an active nucleus, but the AGN contribution to the bolometric luminosity is relevant only in similar to 15-20 per cent of the sources. Overall, ULIRGs appear to be powered by the starburst process, responsible for > 85 per cent of the observed infrared luminosity. The subsample of sources optically classified as low-ionization nuclear emission-line regions (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.

• 出版日期2010-1-1
• 单位中国科学院国家天文台