Metallicity evolution of direct collapse black hole hosts: CR7 as a case study

Bhaskar Agarwal, Jarrett L. Johnson, Sadegh Khochfar, Eric Pellegrini, Claes-Erik Rydberg, Ralf S. Klessen, Pascal Oesch

Research output: Contribution to journalArticlepeer-review

Abstract

In this study, we focus on the z ∼ 6.6 Lyman α CR7 consisting of clump A, which is host to a potential direct collapse black hole (DCBH), and two metal-enriched star-forming clumps B and C. In contrast to claims that signatures of metals rule out the existence of DCBHs, we show that metal pollution of A from star-forming clumps B and C is inevitable, and that A can form a DCBH well before its metallicity exceeds the critical threshold of 10^{-5}-10^{-6} Z_{{⊙}}. Assuming that metal mixing happens instantaneously, we derive the metallicity of A based on the star formation history of B and C. We find that treating a final accreting BH of 106-107 M⊙ in A for nebular emission already pushes its H160 - [3.6] and [3.6] - [4.5] colours into the 3σ limit of observations. Hence, we show that the presence of metals in DCBH hosts is inevitable, and that it is the coevolution of the Lyman-Werner radiation field and metals originating from neighbouring galaxies that governs DCBH formation in neighbouring initially pristine atomic cooling haloes.
Original languageEnglish
Pages (from-to)231-236
JournalMonthly Notices of the Royal Astronomical Society
Volume469
Issue number1
DOIs
Publication statusPublished - 30 Mar 2017

Keywords

  • quasars: supermassive black holes
  • dark ages
  • reionization
  • first stars
  • early Universe
  • cosmology: theory

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