NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-03-26 T05:23:53 PDT
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For refcode 2015AJ....150...43T:
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2015AJ....150...43T Star Formation in the Central Regions of Active and Normal Galaxies Tsai, Mengchun; Hwang, Chorng-Yuan Abstract. We investigated the properties of the host galaxies of active galactic nuclei (AGNs). We used radio emission around the nuclei of the host galaxies to represent AGN activity and used infrared (IR) emission to represent the star-forming activity and stellar population of the host galaxies. We determined that active galaxies have higher stellar masses (SMs) within the central kiloparsec radius than normal galaxies do independent of the Hubble types of the host galaxies; but both active and normal galaxies exhibit similar specific star formation rates (SSFRs), ranging between {10}^-10.5^ and {10}^-9.5^ yr^-1^. We find that the central SM surface density might be used as an indicator to identify AGNs. We also discovered that certain AGNs exhibit substantial inner stellar structures in the IR images; most of the AGNs with inner structures are Seyferts, whereas only a few LINERs exhibit inner structures. We note that the AGNs with inner structures show a positive correlation between the radio activity of the AGNs and the SFRs of the host galaxies, but the sources without inner structures show a negative correlation between the radio power and the SFRs. These results might be explained with a scenario of starburst--AGN evolution. In this scenario, AGN activities are triggered following a nuclear starburst; during the evolution, AGN activities are accompanied by SF activity in the inner regions of the host galaxies; at the final stage of the evolution, the AGNs might transform into LINERs, exhibiting weak SF activity in the central regions of the host galaxies. Key words: galaxies: active, galaxies: evolution, galaxies: nuclei, galaxies: Seyfert, galaxies: star formation
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