Investigating the Structure of the Broad Line Region in AGN with Reverberation Mapping

Both theoretical and observational evidence suggests that galaxies and their central supermassive black holes are connected. In order to understand these connections, we must have accurate measurements of supermassive black hole masses in objects across the observable universe. All black hole mass measurements in distant galaxies are made using emission lines in active galactic nuclei (AGN) -- however, the unknown conditions within the broad line-emitting region could be a source of serious systematic errors in black hole mass measurements in these objects. I will discuss the use of reverberation mapping techniques to probe the geometry and kinematics of the broad line region in active galactic nuclei to help better constrain black hole mass estimates in these galaxies and understand the physics of the BLR. I will highlight recent results from reverberation campaigns carried out by my group at OSU, which have given us new insight into the physical conditions in the broad line region.

Luminous and dark matter in early-type galaxies

Early-type galaxies are believed to grow as a result of mergers, but the details of this process are still largely unknown. Do the mergers involve galaxies of comparable mass (major) or are they dominated by small systems (minor)? Is there dissipation (wet) or not (dry)? Different processes leave different signatures on the mass structure of early-type galaxies. Gravitational lensing provides a unique way to detect these signatures. The SL2S project measured the evolution of the mass profile of early-type galaxies during the last 7 billion years, including constraints on the mean density slope, dark matter fraction, inner dark matter slope and stellar IMF. Based on the collected data, we find that theoretical models for the evolution of early-type galaxies through purely dry mergers are unable to reproduce the observed trends. Additional physical processes, likely related to baryonic physics, are necessary to match the entire set of observables.

Robotic, Extreme & Beyond: Rayleigh Laser Guide Stars Pioneering the Next Decade of Astronomical Adaptive Optics

Rayleigh laser guide stars are currently enjoying a resurgence in the field of astronomical adaptive optics - enabling unique cutting edge science for even the largest of telescope apertures. I will outline the advantages of the Rayleigh laser architecture for compensating the effects of the turbulent atmosphere and detail current and future systems that exploit these lasers to their fullest, including: Robo-AO, the world's first robotic adaptive optics system which is able to observe an unprecedented 200+ targets at the visible diffraction-limit in a single night; PULSE, an upgrade to the currently operating PALM-3000 exoplanet adaptive optics system which will allow it to directly search for planets around much fainter (and more numerous) M-dwarf stars; and several ground layer adaptive optics systems which use multiple Rayleigh laser guide stars to correct for fields of view of up to 1 degree.

The Cluster Mass Scale and Planck

Galaxy cluster abundance and evolution is a good tracer of cosmic structure evolution, providing low-redshift constraints on cosmological parameters that complement those from the cosmic microwave background (CMB). The recent Planck results show some tension between cluster and CMB constraints in the context of the standard, flat cosmological model with a cosmological constant (LCDM). This could signal the need for extensions of the LCDM model, such as non-minimal neutrino mass; it could also indicate that the cluster mass scale requires revision. Cluster masses are the key quantity for cluster based constraints, and remain their largest source of uncertainty. I will discuss the Planck tension between CMB and cluster constraints, and the status of our understanding of the cluster mass scale, including recent gravitational lensing determinations.