Edinburgh Research Explorer

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

Research output: Contribution to journalArticle

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

Related Edinburgh Organisations

Open Access permissions


Original languageEnglish
Pages (from-to)231-236
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 30 Mar 2017


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.

    Research areas

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

ID: 42808803