Multiplicity functions of quasars: predictions from the MassiveBlackII simulation

Journal Article · 20 January 2020 · Monthly Notices of the Royal Astronomical Society

DOI: https://doi.org/10.1093/mnras/staa172 · OSTI ID:1598908

Bhowmick, Aklant K.  ^[1]; Di Matteo, Tiziana ^[1]; Myers, Adam D. ^[2]

---

1. McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
2. Department of Physics & Astronomy, University of Wyoming, 1000 University Ave., Laramie, WY 82071, USA

ABSTRACT We examine multiple active galactic nucleus (AGN) systems (triples and quadruples, in particular) in the MassiveBlackII simulation over a redshift range of 0.06 ≲ z ≲ 4. We identify AGN systems (with bolometric luminosity $$L_{\mathrm{bol}}\gt 10^{42}~\mathrm{erg\, s}^{-1}$$) at different scales (defined by the maximum distance between member AGNs) to determine the AGN multiplicity functions. This is defined as the volume/surface density of AGN systems per unit richness R, the number of AGNs in a system. We find that gravitationally bound multiple AGN systems tend to populate scales of $${\lesssim}0.7~\mathrm{cMpc}\, h^{-1}$$; this corresponds to angular separations of ≲100 arcsec and a line-of-sight velocity difference $${\lesssim}200~\mathrm{km\, s}^{-1}$$. The simulation contains ∼10 and ∼100 triples/quadruples per deg2 up to depths of DESI (g ≲ 24) and LSST (g ≲ 26) imaging, respectively; at least $$20{{\ \rm per\ cent}}$$ of these should be detectable in spectroscopic surveys. The simulated quasar ($$L_{\mathrm{bol}}\gt 10^{44}~\mathrm{erg\, s}^{-1}$$) triples and quadruples predominantly exist at 1.5 ≲ z ≲ 3. Their members have black hole masses $$10^{6.5}\lesssim M_{\mathrm{ bh}}\lesssim 10^{9}~\mathrm{M}_{\odot }\, h^{-1}$$ and live in separate (one central and multiple satellite) galaxies with stellar masses $$10^{10}\lesssim M_{*}\lesssim 10^{12}~\mathrm{M}_{\odot }\, h^{-1}$$. They live in the most massive haloes (e.g. $${\sim}10^{13}~\mathrm{M}_{\odot }\, h^{-1}$$ at z = 2.5; $${\sim}10^{14}~\mathrm{M}_{\odot }\, h^{-1}$$ at z = 1) in the simulation. Their detections provide an exciting prospect for understanding massive black hole growth and their merger rates in galaxies in the era of multimessenger astronomy.

• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• Grant/Contract Number: SC0019022
• OSTI ID: 1598908
• Journal Information: Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Journal Issue: 4 Vol. 492; ISSN 0035-8711
• Publisher: Royal Astronomical SocietyCopyright Statement
• Country of Publication: United Kingdom
• Language: English