2016ApJ...818..172G

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 < M_bh/M_☉≲ 10⁷). How this extends into the realm of intermediate-mass black holes (10² < M_bh/M_☉< 10⁵) is not yet clear, although for the barred Sm galaxy LEDA 87300, Baldassare et al. recently reported a nominal virial mass of M_bh= 5x10⁴ M_☉ residing in a ''spheroid'' of stellar mass equal to 6.3x10⁸ M_☉. We point out, for the first time, that LEDA 87300 therefore appears to reside on the near-quadratic M_bh-M_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_bulge= 0.9x10⁸ M_☉and M_bulge/M_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) and black hole mass (M_bh = 2.9_–2.3^+6.7 x 10⁴f_2.3 M_☉) and show that LEDA 87300 remains consistent with the M_bh-σ relation, and also the near-quadratic M_bh-M_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.