Observational signatures of massive black hole formation in the early Universe

Abstract

We study a simulation of a nascent massive, so-called direct-collapse, black hole that induces a wave of nearby massive metal-free star formation, unique to this seeding scenario and to very high redshifts. We implement a dynamic, fully-three dimensional prescription for black hole radiative feedback, star formation, and radiative transfer to explore the observational signatures of the massive black hole hosting galaxy. We find a series of distinct colors and emission line strengths, dependent on the relative strength of star formation and black hole accretion. We predict that the forthcoming James Webb Space Telescope might be able to detect and distinguish a young galaxy that hosts a direct-collapse black hole in this configuration at redshift 15 with as little as a 20,000-second total exposure time across four filters, critical for constraining supermassive black hole seeding mechanisms and early growth rates. We also find that a massive seed black hole produces strong, H 2 -dissociating Lyman-Werner radiation. 1 arXiv:1809.03526v1 [astro-ph.GA] 10 Sep 2018The existence of quasars when the Universe was less than a billion years old 1-5 implies that their progenitors are seeded at very early times and grow rapidly. However, black hole growth rates 6,7 are limited by their own radiation feedback, requiring models to either demonstrate high accretion rates or a massive black hole seed 8,9 . In the presense of a Lyman-Werner (LW; 11.2 -13.6 eV) background, the formation of molecular hydrogen (H 2 ) in a primordial, star-less halo is suppressed and the gas can only cool atomically 10, 11 . After reaching a virial temperature of ∼ 10 4 K, these "atomic cooling" halos collapse isothermally to hydrogen number densities of 10 6 cm −3 without fragmenting 12 . After which, the gas becomes optically thick to Ly-α, and we expect the medium to begin a runaway collapse that eventually leads to the formation of a massive (10 3 − 10 5 M ) direct collapse black hole (DCBH) [13][14][15] .We simulate the evolution of a DCBH-hosting halo using the radiation hydrodynamics ENZO 16 code. In our simulation, star formation is suppressed by the dissociation of molecular hydrogen (H 2 ) due to an isotropic, strong (10 3 J 21 * ), and constant LW background, which we apply from z = 30 until the end of the simulation. Prior to the introduction of the black hole at z = 15, our host halo has a virial temperature of ∼ 10 4 K, is hydrodynamically collapsing, is metal-free, and hosts no prior star formation, which is physically conincident with the conditions preceeding DCBH formation. Chon et al. (2016) 17 suggest a peak in the frequency of DCBH formation around z ≈ 15 and we focus on this value for our analysis in light of observational evidence of * J 21 ≡ 10 −21 erg s −1 cm −2 Hz −1 sr −1

The seeds of supermassive black holes and the role of local radiation and metal spreading

“…Lately, Barrow et al (2018) have suggested observational features of DCBH, claiming that the upcoming JWST telescope might be able to detect and distinguish a young galaxy that hosts a DCBH at z ∼ 15.…”

“…Popular analytical models require a number of hypotheses to allow the gas to collapse without fragmenting (see e.g. Bromm & Loeb 2003;Begelman et al 2006;Mayer et al 2010;Visbal et al 2014;Choi et al 2015;Valiante et al 2016Valiante et al , 2017Regan et al 2017;Barrow, Aykutalp, & Wise 2018;Chon, Hosokawa, & Yoshida 2018, for details and reviews).…”

Intermediate-Mass Black Holes

“…Finally, first JWST and then a Lynx-like mission in the X-ray, should each be sensitive to ∼ 10 5 MBH black holes even at z ≈ 10 (e.g., Barrow et al 2018. The challenge will be identifying such accreting low-mass black holes, which will require extensive multi-wavelength data.…”

On the Evolution of Supermassive Primordial Stars in Cosmological Flows

“…Previous studies have shown that Pop III SMSs with masses similar to those in our models would have extremely large luminosities that could be detected in the near infrared (NIR) by the James Webb Space Telescope (JWST) and large ground-based telescopes in the coming decade (Hosokawa et al 2013;Surace et al 2018Surace et al , 2019Whalen et al 2020b). Their BHs could also be found in the NIR at z ∼ 15 − 20 by JWST (Pacucci et al 2015;Natarajan et al 2017;Barrow et al 2018;Whalen et al 2020a) and at z ∼ 6 -8 by Euclid and the Roman Space Telescope (although lensing by galaxy clusters and massive galaxies in their wide fields could extend these detections up to z 10 -15; Vikaeus et al 2021). DCBHs will only be marginally visible to the Square Kilometre Array or next-generation Very Large Array in the radio at z 6 -8 (Whalen et al 2020b) but would become more luminous after growing to larger masses at later times.…”