Investigation on the Evolution and Unification of Active Galaxies with Observations of Sdss, Panstarrs, and Alma

Project Details


The origin of galaxies and active galactic nuclei (AGNs) is still one of the most important mysteriesof modern astronomy. It is now generally believed that AGNs were co-evolved with galaxies. It is knownthat there is a significant correlation between the masses of the central super mass black holes (SMBHs) andthe masses of galactic spheroids, and the energy of the AGN is originated from the SMBH and thesurrounding accretion disk and gas. However, it is still unclear that in what circumstance a galaxy will hostan AGN. For example, we expect the mass of the SMBH in the detected high-redshift QSOs should be veryhuge given the high luminosity of these sources. However, on the other hand, the galaxies at such highredshifts should be just at the earliest stage of the galaxy evolution and would not be expected to be verylarge. It is thus unclear what is the relation of these high-redshift QSOs and their host galaxies. Anothergeneral problems include: Why different AGNs have different observed properties? Do different AGNshave different origins or they can be connected within a unification framework? Do type 1 and type 2AGNs have different host galaxies? Are different types of AGNs intrinsically different or just viewed indifferent orientations? If they are intrinsically different, what is the origin of the difference? The purpose ofthis project is to study on these important issues following our previous results.In the past few years, we have obtained some important results relevant to the answers of theseproblems. For examples, we found that the host galaxies of Seyfert 1 and Seyfert 2 AGNs have differenthost galaxy populations; this result cannot be explained with the traditional unification model. Besides, wealso found that AGN activity is related to star formation activity of the host galaxy only for some particularmorphological types of galaxies; and nearby AGNs only exist in the galaxies with historic nuclear starburst.We found the phenomenon of color variability for some red QSOs. We discovered a Ly α luminoushigh-redshift QSOs, has a very narrow Ly α line similar to the local narrow-line Seyfert 1 galaxies. We alsofound some normal elliptical galaxies, which show significant star formation rates, but the mechanisms thattrigger the star formation activity is still unclear.In this project, we will use different observational techniques to probe relevant questions. Our studywill utilize optical/near infrared spectral observations, millimeter and sub-millimeter observations, opticalvariability observations, and sky survey data analyses to investigate related problems in the connection ofgalaxy-AGN evolution.We will use a lot of telescopes in other countries, and thus require traveling budgets for overseaobservations. This project will provide observational training for graduate students and postdocs. Theresults of this project are expected to have important impacts on the field of AGN researches.
Effective start/end date1/08/1731/07/18


  • galaxy formation
  • QSOs
  • active galactic nuclei
  • unification model of AGN


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