Fall 2015






Anthony Pullen

Constraining Gravity at the Largest Scales through CMB Lensing and Galaxy Velocities

We discuss recent work exploring the use of CMB lensing to probe EG, the ratio between curvature and velocity perturbations. This quantity is distinct for various gravity models, breaking the degeneracy in current cosmological probes of gravity and dark energy. While the lensing signal within EG has traditionally been probed with galaxy-galaxy lensing, galaxy-CMB lensing is a more robust lensing tracer that can probe EG at higher redshifts with fewer astrophysical uncertainties. We present constraints to EG using CMB data from Planck and galaxy data from the SDSS BOSS survey, which are consistent with general relativity (GR). We also show forecasts for future surveys, finding that upcoming photometric surveys combined with next-generation CMB surveys like Advanced ACTPol could produce <1%-level constraints that could potentially rule out alternatives to GR.



Anne Medling

From Nuclear Outflows to Galactic Winds

The evolution of a galaxy depends heavily on its gas content: gas both forms stars and fuels black hole growth. These processes may be capable of self-regulating, since both star formation and AGN activity can drive outflows that may remove gas from the host galaxy's reservoir. Such outflows are challenging to study because of the wide range of scales involved. Distinguishing between launching mechanisms requires high spatial resolution, but such observations usually are too limited in field-of-view to determine what effect an outflow has on galactic scales. I will present some first results from our two-pronged approach, which combines wide-field optical integral field spectroscopy tracing galactic winds on several kpc scales and AO-assisted near-infrared integral field spectroscopy to zoom in on the launch regions of these winds. The combination of these observations is a powerful way to connect the physical mechanisms driving galactic winds to the physical effects these winds can have on their host galaxies.








Chris Hayward





Partick Ogle

Superluminous Spiral Galaxies

We have discovered a new population of spiral galaxies that are as luminous as brightest cluster ellipticals. Super spirals are also massive, with stellar masses of 310-311 M, and giant, with isophotal diameters of 60-135 kpc. They fall above an extension of the star-forming galaxy main sequence, with star formation rates of 5-65 M/yr. They are found in a range of environments, from isolation to the centers of galaxy clusters. However, they are very rare in the local universe, with the closest one at a redshift of 0.09, and a space density of 30 per cubic Gpc. I will discuss the implications of the existence of such massive, gas rich galaxies for galaxy formation and evolution.

Dec 9

Finals Week