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Benjamin Boizelle
September 3, 201811:30 am – 12:30 pm (CDT)

Precision Black Hole Mass Measurement in Luminous Early-type Galaxies


Benjamin Boizelle (Texas A&M University)



Mitchell Institute for Fundamental Physics & Astronomy

College Station, Texas 77843

Event Details

The supermassive black hole (BH) census remains very incomplete at the highest masses(&109M), limiting our understanding of BH/host galaxy co-evolution for the most mas-sive galaxies. I present analysis of circumnuclear ionized atomic and both warm and coldmolecular gas kinematics, as well as results of detailed gas-dynamical modeling, for a sampleof nearby, luminous early-type galaxies (ETGs). Keck OSIRIS integral-field unit andHubbleSpace Telescope(HST) STIS spectroscopy reveal H21−0 S(1) and Hαin approximately Ke-plerian rotation within NGC 1275. We build and optimize models of dynamically-warm diskrotation to better constrain its BH massMBH= (1.20+0.32−0.44)×109M, although significantturbulent velocity dispersion complicates model fitting. Dynamically cold molecular gas emission is free from nearly all of the systemics that plagueMBHdetermination when using dynamically warm tracers. I present Atacama Large Mil-limeter/submillimeter Array (ALMA)∼0.′′3−resolution CO(2−1) and continuum imagingof a sample of early-type galaxies (ETGs) that host circumnuclear dusty disks. Given theirincredible data sensitivities, these dynamically cold disks yield the most sensitive possibletracers of the central gravitational potential. In several targets we detect central velocity up-turns that suggest unresolved Keplerian rotation. We find these disks are formally stabilizedagainst fragmentation and gravitational collapse. The continuum emission is in all casesxi dominated by a central, unresolved source and appears to be consistent with hot accretion. I present follow-up, 0.′′1−resolution CO(2−1) imaging of one of these promising ETGs – NGC3258 – to highly resolve its BH sphere of influence and map out the molecular kinematicsin exquisite detail. Its very regular, nearly symmetric rotation enables the most detailedthin disk modeling to date. Moderate kinematic twists are incorporated using tilted-ringformalism, and the extended mass profile is amended to allow for a variable stellar massdensity profile. Preliminary model optimization returnsMBH= 2.23×109Mwith ananticipated total uncertainty of around 5%.

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