The Role of Starburst-AGN composites in Luminous Infrared Galaxy Mergers: Insights from the New Optical Classification Scheme - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate




The Role of Starburst-AGN composites in Luminous Infrared Galaxy Mergers: Insights from the New Optical Classification Scheme - Astrophysics > Cosmology and Nongalactic Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We investigate the fraction of starbursts, starburst-AGN composites,Seyferts, and LINERs as a function of infrared luminosity L IR and mergerprogress for ~500 infrared-selected galaxies. Using the new opticalclassifications afforded by the extremely large data set of the Sloan DigitalSky Survey, we find that the fraction of LINERs in IR-selected samples is rare< 5% compared with other spectral types. The lack of strong infrared emissionin LINERs is consistent with recent optical studies suggesting that LINERscontain AGN with lower accretion rates than in Seyfert galaxies. Mostpreviously classified infrared-luminous LINERs are classified as starburst-AGNcomposite galaxies in the new scheme. Starburst-AGN composites appear to-bridge- the spectral evolution from starburst to AGN in ULIRGs. The relativestrength of the AGN versus starburst activity shows a significant increase athigh infrared luminosity. In ULIRGs L IR >10^12 L odot, starburst-AGNcomposite galaxies dominate at early-intermediate stages of the merger, andAGN galaxies dominate during the final merger stages. Our results areconsistent with models for IR-luminous galaxies where mergers of gas-richspirals fuel both starburst and AGN, and where the AGN becomes increasinglydominant during the final merger stages of the most luminous infrared objects.



Author: T.-T. Yuan, L. J. Kewley, D. B. Sanders IfA, Hawaii

Source: https://arxiv.org/



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