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  • DOES THE INTERMEDIATE-MASS ...
    Graham, Alister W.; Ciambur, Bogdan C.; Soria, Roberto

    The Astrophysical journal, 02/2016, Volume: 818, Issue: 2
    Journal Article

    ABSTRACT 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 (105 < Mbh/M 107). How this extends into the realm of intermediate-mass black holes (102 < Mbh/M < 105) is not yet clear, although for the barred Sm galaxy LEDA 87300, Baldassare et al. recently reported a nominal virial mass of Mbh = 5 × 104 M residing in a "spheroid" of stellar mass equal to 6.3 × 108 M . We point out, for the first time, that LEDA 87300 therefore appears to reside on the near-quadratic Mbh-Msph,* 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 Mbulge = 0.9 × 108 M and Mbulge/Mdisk = 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−1) and black hole mass ( ) and show that LEDA 87300 remains consistent with the Mbh- relation, and also the near-quadratic Mbh-Msph,* 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.