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Title: STAR FORMATION IN SELF-GRAVITATING DISKS IN ACTIVE GALACTIC NUCLEI. I. METALLICITY GRADIENTS IN BROAD-LINE REGIONS

Abstract

It has been suggested that the high metallicity generally observed in active galactic nuclei (AGNs) and quasars originates from ongoing star formation in the self-gravitating part of accretion disks around supermassive black holes (SMBHs). We designate this region as the star-forming (SF) disk, in which metals are produced from supernova explosions (SNexp) while at the same time inflows are driven by SNexp-excited turbulent viscosity to accrete onto the SMBHs. In this paper, an equation of metallicity governed by SNexp and radial advection is established to describe the metal distribution and evolution in the SF disk. We find that the metal abundance is enriched at different rates at different positions in the disk, and that a metallicity gradient is set up that evolves for steady-state AGNs. Metallicity as an integrated physical parameter can be used as a probe of the SF disk age during one episode of SMBH activity. In the SF disk, evaporation of molecular clouds heated by SNexp blast waves unavoidably forms hot gas. This heating is eventually balanced by the cooling of the hot gas, but we show that the hot gas will escape from the SF disk before being cooled, and diffuse into the broad-line regions (BLRs)more » forming with a typical rate of {approx}1 M{sub sun} yr{sup -1}. The diffusion of hot gas from an SF disk depends on ongoing star formation, leading to the metallicity gradients in BLR observed in AGNs. We discuss this and other observable consequences of this scenario.« less

Authors:
; ; ; ; ;  [1];  [2];  [3];  [4]
  1. Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049 (China)
  2. Physics and Astronomy Department, 3270 Biomedical Physical Sciences Building, Michigan State University, East Lansing, MI 48824 (United States)
  3. Department of Physics and Astronomy, 177 Chemistry/Physics Building, University of Kentucky, Lexington, KY 40506 (United States)
  4. National Astronomical Observatories of China, Chinese Academy of Sciences, 20A Datun Road, Beijing 100020 (China)
Publication Date:
OSTI Identifier:
21587524
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 739; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/739/1/3; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; ADVECTION; BLACK HOLES; EXPLOSIONS; GALACTIC EVOLUTION; GALAXY NUCLEI; METALS; QUASARS; STARS; COSMIC RADIO SOURCES; ELEMENTS; EVOLUTION; MASS TRANSFER

Citation Formats

Wang Jianmin, Ge Junqiang, Hu Chen, Li Yanrng, Xiang Fei, Zhang Shu, Baldwin, Jack A., Ferland, Gary J., and Yan Changshuo, E-mail: wangjm@mail.ihep.ac.cn. STAR FORMATION IN SELF-GRAVITATING DISKS IN ACTIVE GALACTIC NUCLEI. I. METALLICITY GRADIENTS IN BROAD-LINE REGIONS. United States: N. p., 2011. Web. doi:10.1088/0004-637X/739/1/3; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Wang Jianmin, Ge Junqiang, Hu Chen, Li Yanrng, Xiang Fei, Zhang Shu, Baldwin, Jack A., Ferland, Gary J., & Yan Changshuo, E-mail: wangjm@mail.ihep.ac.cn. STAR FORMATION IN SELF-GRAVITATING DISKS IN ACTIVE GALACTIC NUCLEI. I. METALLICITY GRADIENTS IN BROAD-LINE REGIONS. United States. doi:10.1088/0004-637X/739/1/3; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Wang Jianmin, Ge Junqiang, Hu Chen, Li Yanrng, Xiang Fei, Zhang Shu, Baldwin, Jack A., Ferland, Gary J., and Yan Changshuo, E-mail: wangjm@mail.ihep.ac.cn. Tue . "STAR FORMATION IN SELF-GRAVITATING DISKS IN ACTIVE GALACTIC NUCLEI. I. METALLICITY GRADIENTS IN BROAD-LINE REGIONS". United States. doi:10.1088/0004-637X/739/1/3; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
@article{osti_21587524,
title = {STAR FORMATION IN SELF-GRAVITATING DISKS IN ACTIVE GALACTIC NUCLEI. I. METALLICITY GRADIENTS IN BROAD-LINE REGIONS},
author = {Wang Jianmin and Ge Junqiang and Hu Chen and Li Yanrng and Xiang Fei and Zhang Shu and Baldwin, Jack A. and Ferland, Gary J. and Yan Changshuo, E-mail: wangjm@mail.ihep.ac.cn},
abstractNote = {It has been suggested that the high metallicity generally observed in active galactic nuclei (AGNs) and quasars originates from ongoing star formation in the self-gravitating part of accretion disks around supermassive black holes (SMBHs). We designate this region as the star-forming (SF) disk, in which metals are produced from supernova explosions (SNexp) while at the same time inflows are driven by SNexp-excited turbulent viscosity to accrete onto the SMBHs. In this paper, an equation of metallicity governed by SNexp and radial advection is established to describe the metal distribution and evolution in the SF disk. We find that the metal abundance is enriched at different rates at different positions in the disk, and that a metallicity gradient is set up that evolves for steady-state AGNs. Metallicity as an integrated physical parameter can be used as a probe of the SF disk age during one episode of SMBH activity. In the SF disk, evaporation of molecular clouds heated by SNexp blast waves unavoidably forms hot gas. This heating is eventually balanced by the cooling of the hot gas, but we show that the hot gas will escape from the SF disk before being cooled, and diffuse into the broad-line regions (BLRs) forming with a typical rate of {approx}1 M{sub sun} yr{sup -1}. The diffusion of hot gas from an SF disk depends on ongoing star formation, leading to the metallicity gradients in BLR observed in AGNs. We discuss this and other observable consequences of this scenario.},
doi = {10.1088/0004-637X/739/1/3; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 739,
place = {United States},
year = {2011},
month = {9}
}