Year: 2023
Type: article
Abstract: ABSTRACT We investigate the coalescence of massive black hole ($M_{\rm BH}\gtrsim 10^{6}~\rm {\rm M}_{\odot }$) binaries (MBHBs) at 6 < z < 10 by adopting a suite of cosmological hydrodynamical simulations of galaxy formation, zoomed-in on biased (>3σ) overdense regions (Mh ∼ 1012 M⊙ dark matter haloes at z = 6) of the Universe. We first analyse the impact of different resolutions and AGN feedback prescriptions on the merger rate, assuming instantaneous mergers. Then, we compute the halo bias correction factor due to the overdense simulated region. Our simulations predict merger rates that range between 3 and 15 $\rm yr^{-1}$ at z ∼6, depending on the run considered, and after correcting for a bias factor of ∼20−30. For our fiducial model, we further consider the effect of delay in the MBHB coalescence due to dynamical friction. We find that 83 per cent of MBHBs will merge within the Hubble time, and 21 per cent within 1 Gyr, namely the age of the Universe at z > 6. We finally compute the expected properties of the gravitational wave (GW) signals and find the fraction of LISA detectable events with high signal-to-noise ratio (SNR > 5) to range between 66 per cent and 69 per cent. However, identifying the electro-magnetic counterpart of these events remains challenging due to the poor LISA sky localization that, for the loudest signals ($\mathcal {M}_c\sim 10^6~{{\rm M}_{\odot }}$ at z = 6), is around 10 $\rm deg^2$.
Institutions: Scuola Normale Superiore, Istituto Nazionale di Fisica Nucleare, Sezione di Milano Bicocca, University of Milano-Bicocca, University of Trieste, Trieste Astronomical Observatory, Excellence Cluster Origins, Ludwig-Maximilians-Universität München, National Institute for Astrophysics, Osservatorio di Astrofisica e Scienza dello Spazio, Universidade Federal do ABC
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: European Commission, Deutsche Forschungsgemeinschaft, Fundação de Amparo à Pesquisa do Estado de São Paulo, Ministero dell’Istruzione, dell’Università e della Ricerca, Agenzia Spaziale Italiana, Istituto Nazionale di Astrofisica, Carl Friedrich von Siemens Stiftung, Horizon 2020 Framework Programme, H2020 European Research Council
Awards: G1128111471, G1241286074, G1897041155, Black hole winds and the baryon life cycle of galaxies: the stone-guest at the galaxy evolution supper, G2875271262, G4066435496, EXC 2094: ORIGINS: Vom Ursprung des Universums bis zu den ersten Bausteinen des Lebens, G4590720103, G4660792063, G4937468798, G6315092050, High-energy astrophysics of galaxies and AGN in the cosmological context by connecting numerical simulations and observations with the CTA and ASTRI Mini-Array, G7114379246, G7636030831, G8087438264
OpenAlex ID: W4376636063