Unveiling the First Black Holes with JWST:Multi-wavelength Spectral Predictions

Priyamvada Natarajan, Fabio Pacucci, Andrea Ferrara, Bhaskar Agarwal, Angelo Ricarte, Erik Zackrisson, Nico Cappelluti

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Growing supermassive black holes (∼109 M) that power luminous z > 6 quasars from light seeds-the remnants of the first stars-within a Gyr of the Big Bang poses a timing challenge. The formation of massive black hole seeds via direct collapse with initial masses∼104105 M alleviates this problem. Viable direct-collapse black hole formation sites, the satellite halos of star-forming galaxies, merge and acquire stars to produce a new, transient class of high-redshift objects, obese black hole galaxies (OBGs). The accretion luminosity outshines that of the stars in OBGs. We predict the multi-wavelength energy output of OBGs and growing Pop III remnants at z = 9 for standard and slim disk accretion, as well as high and low metallicities of the associated stellar population. We derive robust selection criteria for OBGs-a pre-selection to eliminate blue sources, followed by colorcolor cuts ([F090W - F220W] > 0; -0.3 < [F200W - F444W] < 0.3) and the ratio of X-ray flux to rest-frame optical flux (FX/ F444W ≫ 1). Our cuts sift out OBGs from other bright, high- and low-redshift contaminants in the infrared. OBGs with predicted MAB < 25 are unambiguously detectable by the Mid-Infrared Instrument (MIRI), on the upcoming James Webb Space Telescope (JWST). For parameters explored here, growing Pop III remnants with predicted MAB < 30 will likely be undetectable by JWST. We demonstrate that JWST has the power to discriminate between initial seeding mechanisms.

Original languageEnglish (US)
Article number117
JournalAstrophysical Journal
Issue number2
StatePublished - Apr 1 2017
Externally publishedYes


  • cosmology: observations
  • dark ages, reionization, first stars
  • early universe
  • galaxies: photometry
  • quasars: supermassive black holes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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