Mass Deficits, Stalling Radii, and the Merger Histories of Elliptical Galaxies

By D. Merritt. 2006

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A binary supermassive black hole leaves an imprint on a galactic nucleus in the form of a "mass deficit," a decrease in the mass of the nucleus due to ejection of stars by the binary. The magnitude of the mass deficit is in principle related to the galaxy's merger history, but the relation has never been quantified. Here high-accuracy N-body simulations are used to calibrate this relation. Mass deficits are shown to be Mdef ≈ 0.5M12, with M12 the total mass of the binary; the coefficient in this relation is found to depend only weakly on M2/M1 or on the galaxy's preexisting nuclear density profile. Hence, after 𝒩 mergers, Mdef ≈ 0.5𝒩M•, with M• the final (current) black hole mass. When compared with observed mass deficits, this result implies 1 ≲ 𝒩 ≲ 3, in accord with hierarchical structure formation models. Implications for binary stalling radii, the origin of hypervelocity stars, and the distribution of dark matter at the centers of galaxies are discussed.

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

STRUCTURE AND FORMATION OF ELLIPTICAL AND SPHEROIDAL GALAXIES (2008, background): “These values are very large in comparison to the Merritt (2006) prediction thatMdef/M• ≃ 0.5 per major merger.”
Dynamics of triple black hole systems in hierarchically merging massive galaxies (2006, methodology): “However this final stage of the inspiral is found to proceed very rapidly in N-body simulations (Quinlan & Hernquist 1997; Milosavljevic & Merritt 2001; Merritt 2006).”
Selection bias in dynamically measured supermassive black hole samples: its consequences and the quest for the most fundamental relation (2016, background): “…depleted core, along with their possible correlations with the mass of the central black hole, are also believed to contain information about the types of mergers responsible for shaping the host spheroids (e.g., Aguerri et al. 2001; Merritt 2006; Hilz et al. 2013; Graham & Scott 2013, 2015).”
The SAURON project – IX. A kinematic classification for early‐type galaxies (2007, background): “Cores are thought to be the result of the scouring via a binary supermassive blackhole (Faber et al. 1997; Merritt 2006, and references therein), the poten- tial consequence of a merger.”
Doing Science with eLISA: Astrophysics and Cosmology in the Millihertz Regime (2012, background): “Bright elliptical galaxies show light deficits (cores) in their surface brightness profiles, i.e. lack of stars in their nuclei (Kormendy and Bender, 2009), and this missing light correlates with the mass of the central black hole (Merritt, 2006, Merritt et al., 2007).”
Supermassive black hole binaries in gaseous and stellar circumnuclear discs: orbital dynamics and gas accretion (2006, methodology): “Assuming a SIS profile, ah = 0.25 q rinf/(1 − q) 2 (Merritt 2006), and, for q = 1, ah ≈ 1 pc, while for q = 0.25 (0.1) ah ≈ 0.3 (0.1) pc.”
A LARGE SYSTEMATIC SEARCH FOR CLOSE SUPERMASSIVE BINARY AND RAPIDLY RECOILING BLACK HOLES (2011, unknown): “…that seek to explain the formation of cores in elliptical galaxies following a merger and mass deficits therein (e.g., Milosavljević et al. 2002; Merritt 2006), and the morphologies of some radio sources (such as precessing jets and X-shaped sources; see Roos, Kaastra, & Hummel 1993; Romero…”
The Masses of Nuclear Black Holes in Luminous Elliptical Galaxies and Implications for the Space Density of the Most Massive Black Holes (2006, methodology): “The binary BH ejects a total mass of stars, Mej, that is expected to be proportional to the total mergedM (Quinlan 1996; Milosavljević &Merritt 2001; Merritt 2006).”
A REVISED PARALLEL-SEQUENCE MORPHOLOGICAL CLASSIFICATION OF GALAXIES: STRUCTURE AND FORMATION OF S0 AND SPHEROIDAL GALAXIES (2011, background): “…were made in mergers and that flung stars away from the center as they sunk toward their own eventual merger (Begelman et al. 1980; Ebisuzaki et al. 1991; Makino & Ebisuzaki 1996; Quinlan & Hernquist 1997; Faber et al. 1997; Milosavljević & Merritt 2001; Milosavljević et al. 2002; Merritt 2006).”
Large Merger Recoils and Spin Flips from Generic Black Hole Binaries (2007, methodology): “…are poorly constrained observationally, but the luminous galaxies known to harbor SMBHs are believed to have experienced a few to several major mergers (mass ratios 0.3 <∼ q <∼ 1) over their lifetimes (Haehnelt and Kauffmann 2002; Merritt 2006); mergers with q ≈ 1 were more common in the past.”
Ejection of Supermassive Black Holes from Galaxy Cores (2007, background): “Thus 2ωcTdf ≈ 4 Mc MBH lnΛ (18) In our simulations (and in real galaxies), the right hand side of this expression is& 1, since core masses are∼ a fewMBH (Merritt 2006) and 2. lnΛ .”