Limits on the Masses of Supermassive Black Holes in 105 Nearby Galaxies

Extract

Secure measurements of the mass of the central supermassive black hole, M_BH, in external galaxies are traditionally obtained through the modeling of the stellar and/or gaseous kinematics, most often derived using Hubble Space Telescope (HST) observations in the optical domain. The modeling of the nuclear ionized-gas kinematics has led to accurate M_BH measurements at a relatively cheap cost in terms of observation time compared to stellar-dynamical M_BH determinations. But only a handful of the objects have turned out to have sufficiently regular gas velocity fields for the purpose of modeling. Nevertheless, the HST archive contains a yet untapped resource that can be used to better constrain the M_BH budget across the different morphological types of galaxies, which consists of the vast number of the Space Telescope Imaging Spectrograph (STIS) spectra from which a central emission-line width can be measured. These data allow to put an upper limit on M_BH for a large number of galaxies and promise to compensate for the lack of exact measurements when studying the M_BH–host galaxy relationships.