Does the intermediate-mass black hole in LEDA 87300 (RGG 118) follow the near-quadratic M{sub bh}–M{sub spheroid} relation?
- Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Victoria 3122 (Australia)
- International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia)
The mass scaling relation between supermassive black holes and their host spheroids has previously been described by a quadratic or steeper relation at low masses (10{sup 5} < M{sub bh}/M{sub ⊙} ≲ 10{sup 7}). How this extends into the realm of intermediate-mass black holes (10{sup 2} < M{sub bh}/M{sub ⊙} < 10{sup 5}) is not yet clear, although for the barred Sm galaxy LEDA 87300, Baldassare et al. recently reported a nominal virial mass of M{sub bh} = 5 × 10{sup 4} M{sub ⊙} residing in a “spheroid” of stellar mass equal to 6.3 × 10{sup 8} M{sub ⊙}. We point out, for the first time, that LEDA 87300 therefore appears to reside on the near-quadratic M{sub bh}–M{sub sph,*} relation. However, Baldassare et al. modeled the bulge and bar as the single spheroidal component of this galaxy. Here we perform a 3-component bulge+bar+disk decomposition and find a bulge luminosity which is 7.7 times fainter than the published “bulge” luminosity. After correcting for dust, we find that M{sub bulge} = 0.9 × 10{sup 8} M{sub ⊙} and M{sub bulge}/M{sub disk} = 0.04—which is now in accord with ratios typically found in Scd–Sm galaxies. We go on to discuss slight revisions to the stellar velocity dispersion (40 ± 11 km s{sup −1}) and black hole mass (M{sub bh}=2.9{sub −2.3}{sup +6.7}×10{sup 4} f{sub 2.3} M{sub ⊙}) and show that LEDA 87300 remains consistent with the M{sub bh}–σ relation, and also the near-quadratic M{sub bh}–M{sub sph,*} relation when using the reduced bulge mass. LEDA 87300 therefore offers the first support for the rapid but regulated (near-quadratic) growth of black holes, relative to their host bulge/spheroid, extending into the domain of intermediate-mass black holes.
- OSTI ID:
- 22887010
- Journal Information:
- Astrophysical Journal, Vol. 818, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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