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Title: X-RAY CONSTRAINTS ON THE LOCAL SUPERMASSIVE BLACK HOLE OCCUPATION FRACTION

Distinct seed formation mechanisms are imprinted upon the fraction of dwarf galaxies currently containing a central supermassive black hole. Seeding by Population III remnants is expected to produce a higher occupation fraction than is generated with direct gas collapse precursors. Chandra observations of nearby early-type galaxies can directly detect even low-level supermassive black hole activity, and the active fraction immediately provides a firm lower limit to the occupation fraction. Here, we use the volume-limited AMUSE surveys of ∼200 optically selected early-type galaxies to characterize simultaneously, for the first time, the occupation fraction and the scaling of L {sub X} with M {sub star}, accounting for intrinsic scatter, measurement uncertainties, and X-ray limits. For early-type galaxies with M {sub star} < 10{sup 10} M {sub ☉}, we obtain a lower limit to the occupation fraction of >20% (at 95% confidence), but full occupation cannot be excluded. The preferred dependence of log L {sub X} upon log M {sub star} has a slope of ∼0.7-0.8, consistent with the ''downsizing'' trend previously identified from the AMUSE data set, and a uniform Eddington efficiency is disfavored at ∼2σ. We provide guidelines for the future precision with which these parameters may be refined with largermore » or more sensitive samples.« less
Authors:
; ;  [1] ;  [2] ; ;  [3] ;  [4]
  1. Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)
  2. Department of Astrophysics, Princeton University, Princeton, NJ 08544 (United States)
  3. Physics Department, University of California, Santa Barbara, CA 93106 (United States)
  4. Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul (Korea, Republic of)
Publication Date:
OSTI Identifier:
22364436
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; GALACTIC EVOLUTION; GALAXIES; GALAXY NUCLEI; GRAVITATIONAL COLLAPSE; LIMITING VALUES; X RADIATION