Galaxy bulge formation: Interplay with dark matter halo and central supermassive black hole

Bing-Xiao Xu, Xue-Bing Wu, Hong-Sheng Zhao

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

We present a simple scenario where the formation of galactic bulges was regulated by the dark halo gravity and regulates the growth of the central supermassive black hole. Assuming the angular momentum is low, we suggest that bulges form in a runaway collapse due to the "gravothermal'' instability once the central gas density or pressure exceeds a certain threshold. We emphasize that the threshold is nearly universal, set by the background NFW dark matter gravity g(DM) similar to 1.2 x 10(-8) cm s(-2) in the central cusps of halos. Unlike known thresholds for gradual formation of galaxy disks, we show that the universal "halo-regulated'' star formation threshold for spheroids matches the very high star formation rate and star formation efficiency seen in high-redshift observations of central starburst regions. The starburst feedback also builds up a pressure shortly after the collapse. This large pressure could act both outward to halt further infall of gas from larger scales and inward to counter the Compton-thick wind launched from the central black hole in an Eddington accretion. Assuming the feedback balances inward and outward forces, our scenario naturally gives rise to the black hole-bulge relationships observed in the local universe.

Original languageEnglish
Pages (from-to)198-203
Number of pages6
JournalAstrophysical Journal Letters
Volume664
DOIs
Publication statusPublished - 20 Jul 2007

Keywords

  • black hole physics
  • galaxies : formation
  • galaxies : nuclei
  • galaxies : starburst
  • galaxies : structure
  • ACTIVE GALACTIC NUCLEI
  • STAR-FORMING GALAXIES
  • HIGH-REDSHIFT
  • GRAVITATIONAL-INSTABILITY
  • STARBURST GALAXIES
  • SIGMA RELATION
  • BOYLES LAW
  • GROWTH
  • FEEDBACK
  • QUASARS

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