Elena Dalla Bonta

A Fundamental Relation between Compact Stellar Nuclei, Supermassive Black Holes, and Their Host Galaxies

Imaging surveys with the Hubble Space Telescope (HST) have shown that ?50%-80% of low- and intermediate-luminosity galaxies contain a compact stellar nucleus at their center, regardless of host galaxy morphological type. We combine HST imaging for early-type galaxies from the ACS Virgo Cluster Survey with ground-based long-slit spectra from KPNO to show that the masses of compact stellar nuclei in Virgo Cluster galaxies obey a tight correlation with the masses of the host galaxies. The same correlation is obeyed by the supermassive black holes (SBHs) found in predominantly massive galaxies. The compact stellar nuclei in the Local Group galaxies M33 and NGC 205 are also found to fall along this same scaling relation. These results indicate that a generic by-product of galaxy formation is the creation of a central massive object (CMO)?either an SBH or a compact stellar nucleus?that contains a mean fraction, ?0.2%, of the total galactic mass. In galaxies with masses greater than gal ~ a few × 1010 ?, SBHs appear to be the dominant mode of CMO formation.

The kinematics of σ-drop bulges from spectral synthesis modelling of a hydrodynamical simulation

A minimum in stellar velocity dispersion is often observed in the central regions of disc galaxies. To investigate the origin of this feature, known as a {\sigma}-drop, we analyse the stellar kinematics of a high-resolution N-body + smooth particle hydrodynamical simulation, which models the secular evolution of an unbarred disc galaxy. We compared the intrinsic mass-weighted kinematics to the recovered luminosity-weighted ones. The latter were obtained by analysing synthetic spectra produced by a new code, SYNTRA, that generates synthetic spectra by assigning a stellar population synthesis model to each star particle based on its age and metallicity. The kinematics were derived from the synthetic spectra as in real spectra to mimic the kinematic analysis of real galaxies. We found that the recovered luminosity-weighted kinematics in the centre of the simulated galaxy are biased to higher rotation velocities and lower velocity dispersions due to the presence of young stars in a thin and kinematically cool disc, and are ultimately responsible for the {\sigma}-drop.

A catalogue of nuclear stellar velocity dispersions of nearby galaxies from Hα STIS spectra to constrain supermassive black hole masses

We present new measurements for the nuclear stellar velocity dispersion

Counter-rotating disks in galaxies: dissecting kinematics and stellar populations with 3D spectroscopy

\sigma_{\ast}

Mass Estimations of Supermassive Black Holes in Brightest Cluster Galaxies

within sub-arcsecond apertures for 28 nearby galaxies. Our data consist of Space Telescope Imaging Spectrograph (STIS) long-slit spectra obtained with the G750M grating centred on the H

The V_c-sigma_c relation in high and low surface brightness galaxies

\alpha

The V_circ-σ_c correlation in high and low surface brightness galaxies

spectral range. We fit the spectra using a library of single stellar population models and Gaussian emission lines, while constraining in most cases the stellar-population content from an initial fit to G430L STIS spectra. We illustrate how these

Upper limits on the mass of supermassive black holes from HST/STIS archival data

\sigma_{\ast}

IC 5181: An S0 Galaxy with Ionized Gas on Polar Orbits

measurements can be useful for constraining the mass

The nature of nuclear stellar disks

M_{\bullet}