K. Decker French

The Post-starburst Evolution of Tidal Disruption Event Host Galaxies

We constrain the recent star formation histories of the host galaxies of eight optical/UV-detected tidal disruption events (TDEs). Six hosts had quick starbursts of <200 Myr duration that ended 10 to 1000 Myr ago, indicating that TDEs arise at different times in their hosts post-starburst evolution. If the disrupted star formed in the burst or before, the post-burst age constrains its mass, generally excluding O, most B, and highly massive A stars. If the starburst arose from a galaxy merger, the time since the starburst began limits the coalescence timescale and thus the merger mass ratio to more equal than 12:1 in most hosts. This uncommon ratio, if also that of the central supermassive black hole (SMBH) binary, disfavors the scenario in which the TDE rate is boosted by the binary but is insensitive to its mass ratio. The stellar mass fraction created in the burst is 0.5-10% for most hosts, not enough to explain the observed 30-200x boost in TDE rates, suggesting that the hosts core stellar concentration is more important. TDE hosts have stellar masses 10^9.4 - 10^10.3 Msun, consistent with the SDSS volume-corrected, quiescent Balmer-strong comparison sample and implying SMBH masses of 10^5.5 - 10^7.5 Msun. Subtracting the host absorption line spectrum, we uncover emission lines; at least five hosts have ionization sources inconsistent with star formation that instead may be related to circumnuclear gas, merger shocks, or post-AGB stars.

A Spectroscopic Survey of the Fields of 28 Strong Gravitational Lenses: Implications for H0

EACOA Fellowship - East Asia Core Observatories Association; Technology and Research Initiative Fund (TRIF) Imaging Fellowship program; NSF [AST-1211874, AST-1211385]

A Dependence of the Tidal Disruption Event Rate on Global Stellar Surface Mass Density and Stellar Velocity Dispersion

The rate of tidal disruption events (TDEs),

CHARACTERIZING THE BEST COSMIC TELESCOPES WITH THE MILLENNIUM SIMULATIONS

R_\text{TDE}

Molecular gas during the post-starburst phase: low gas fractions in green-valley Seyfert post-starburst galaxies

, is predicted to depend on stellar conditions near the super-massive black hole (SMBH), which are on difficult-to-measure sub-parsec scales. We test whether

DISCOVERY OF LARGE MOLECULAR GAS RESERVOIRS IN POST-STARBURST GALAXIES

R_\text{TDE}

Joint Strong and Weak Lensing Analysis of the Massive Cluster Field J0850+3604

depends on kpc-scale global galaxy properties, which are observable. We concentrate on stellar surface mass density,

Why Post-starburst Galaxies Are Now Quiescent

\Sigma_{M_\star}

Clocking the Evolution of Post-starburst Galaxies: Methods and First Results

, and velocity dispersion,

The empirical dependence of the tidal disruption event rate on stellar surface mass density and velocity dispersion

\sigma_v