The Physical Connections among Infrared QSOs, Palomar‐Green QSOs, and Narrow‐Line Seyfert 1 Galaxies

We study the properties of infrared-selected QSOs (IR QSOs),optically-selected QSOs (PG QSOs) and Narrow Line Seyfert 1 galaxies (NLS1s).We compare their properties from the infrared to the optical and examinevarious correlations among the black hole mass, accretion rate, star formationrate and optical and infrared luminosities. We find that the infrared excess inIR QSOs is mostly in the far infrared, and their infrared spectral indicessuggest that the excess emission is from low temperature dust heated bystarbursts rather than AGNs. The infrared excess is therefore a usefulcriterion to separate the relative contributions of starbursts and AGNs. Wefurther find a tight correlation between the star formation rate and theaccretion rate of central AGNs for IR QSOs. The ratio of the star formationrate and the accretion rate is about several hundred for IR QSOs, but decreaseswith the central black hole mass. This shows that the tight correlation betweenthe stellar mass and the central black hole mass is preserved in massivestarbursts during violent mergers. We suggest that the higher Eddington ratiosof NLS1s and IR QSOs imply that they are in the early stage of evolution towardclassical Seyfert 1's and QSOs, respectively.Comment: 32 pages, 6 figures, accepted by Ap