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A non-parametric estimate of mass ‘scoured’ in galaxy cores

Hopkins, Philip F. and Hernquist, Lars (2010) A non-parametric estimate of mass ‘scoured’ in galaxy cores. Monthly Notices of the Royal Astronomical Society, 407 (1). pp. 447-457. ISSN 0035-8711.

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We present a simple estimate of the mass ‘deficits’ in cored spheroids, as a function of galaxy mass and radius within the galaxy. Previous attempts to measure such deficits depended on fitting some functional form to the profile at large radii extrapolating inwards; this is sensitive to the assumed functional form and does not allow for variation in nuclear profile shapes. For example, we show that literally interpreting the residuals from a single/cored Sersic function fit as implied ‘deficit’ can be misleading. Instead, we take advantage of larger data sets to directly construct stellar mass profiles of observed systems and measure the stellar mass enclosed in a series of physical radii (M_*(< R)), for samples of cusp and core spheroids at the same stellar mass. We show that there is a significant (model-independent) bimodality in this distribution of central structure for this sample at small radii. We non-parametrically measure the median offset between core and cusp populations (the ‘deficit’ΔM_*(< R)). We can then construct the scoured mass profile as a function of radius, without reference to any assumed functional form. The mass deficit rises in power-law fashion (ΔM_*(< R) ∝ R^(1.3−1.8)) from a significant but small mass at R ≲ 10 pc, to asymptote to a maximum ∼ 0.5–2 M_(BH) at ∼ 100 pc, where M_(BH) is the mass of the central, supermassive black hole (BH) hosted by the spheroid. At larger radii there is no statistically significant separation between populations; the upper limit to the cumulative scoured mass at ∼kpc is ∼ 2–4 M_(BH). This does not depend strongly on stellar mass. The dispersion in M_*(< R) appears larger in the core population, possibly reflecting the fact that core scouring increases the scatter in central profile shapes. We measure this broadening effect as a function of radius. The relatively low mass deficits inferred, and characteristic radii, are in good agreement with models of ‘scouring’ from BH binary systems.

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URLURL TypeDescription Paper ItemComment on "A Non-Parametric Estimate of Mass 'Scoured' in Galaxy Cores"
Hopkins, Philip F.0000-0003-3729-1684
Hernquist, Lars0000-0001-6950-1629
Additional Information:© 2010 The Authors. Journal compilation © 2010 RAS. Accepted 2010 April 24. Received 2010 April 5; in original form 2010 February 11. We thank Hagai Perets for insightful comments in the development of this manuscript. We also thank John Kormendy, Tod Lauer, Eliot Quataert and Norm Murray for helpful discussions at various stages in this and related work. Support for PFH was provided by the Miller Institute for Basic Research in Science, University of California Berkeley. EQ is supported in part by NASA grant NNG06GI68G and the David and Lucile Packard Foundation.
Funding AgencyGrant Number
Miller Institute for Basic Research in ScienceUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Subject Keywords:galaxies: active, galaxies: evolution, galaxies: formation, quasars: general, cosmology: theory
Issue or Number:1
Record Number:CaltechAUTHORS:20200521-163330526
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Official Citation:Philip F. Hopkins, Lars Hernquist, A non-parametric estimate of mass ‘scoured’ in galaxy cores, Monthly Notices of the Royal Astronomical Society, Volume 407, Issue 1, September 2010, Pages 447–457,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103398
Deposited By: George Porter
Deposited On:22 May 2020 18:39
Last Modified:22 May 2020 18:39

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