Effects of the Hubble parameter on the cosmic growth of the first quasars

Author(s)

Nunes, Rafael C. ^[1] ; Pacucci, Fabio ^{[2, 3]}

Affiliation

^[1] Inst Nacl Pesquisas Espaciais, Div Astrofis, Ave Astronautas 1758, BR-12227010 Sao Jose Dos Campos, SP - Brazil

^[2] Harvard Univ, Black Hole Initiat, Cambridge, MA 02138 - USA

^[3] Harvard & Smithsonian, Ctr Astrophys, Cambridge, MA 02138 - USA

• Document type: Journal article
• Source: Monthly Notices of the Royal Astronomical Society; v. 496, n. 1, p. 888-893, JUL 2020.
• Web of Science Citations: 0

Abstract

Supermassive black holes (SMBHs) play a crucial role in the evolution of galaxies and are currently detected up to z similar to 7.5. Theories describing black hole (BH) growth are challenged by how rapidly seeds with initial mass M. less than or similar to 10(5)M(circle dot), formed at z similar to 20-30, grew to M. similar to 10(9)M(circle dot) by z similar to 7. Here we study the effects of the value of the Hubble parameter, H-0, on models describing the early growth of BHs. First, we note that the predicted mass of a quasar at z = 6 changes by > 300 per cent if the underlying Hubble parameter used in the model varies from H-0 = 65 to H-0 = 74 km s(-1) Mpc(-1), a range encompassing current estimates. Employing an MCMC approach based on priors from z greater than or similar to 6.5 quasars and on Ho, we study the interconnection between Ho and the parameters describing BH growth: seed mass M-i and Eddington ratio f(Edd). Assuming an Eddington ratio of f(Edd) = 0.7, in agreement with previous estimates, we find H-0 = 73.6(-3)(.3)(+1.2) km s(-1) Mpc(-1). In a second analysis, allowing all the parameters to vary freely, we find log (M-i/M-circle dot) > 4.5 (at 95 per cent CL), H-0 = 74(-1.4)(+1.5) km s(-1) Mpc(-1) and Add = 0.77(-0.025)(+0.035) at 68 per cent CL. Our results on the typical Eddington ratio are in agreement with previous estimates. Current values of the Hubble parameter strongly favour heavy seed formation scenarios, with M-i greater than or similar to 10(4)M(circle dot). In our model, with the priors on BII masses of quasars used, light seed formation scenarios are rejected at similar to 3 sigma. (AU)

• FAPESP's process: 18/18036-5 - Investigating physical aspects beyond the standard model linked to the themes of dark energy, modified gravity, neutrinos and gravitational waves
• Grantee: Rafael da Costa Nunes
• Support Opportunities: Scholarships in Brazil - Post-Doctoral