David W. Harris

Constraints on Type Ia Supernova Progenitor Companions from Early Ultraviolet Observations with Swift

We compare early ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) with theoretical predictions for the brightness of the shock associated with the collision between SN ejecta and a companion star. Our simple method is independent of the intrinsic flux from the SN and treats the flux observed with the Swift/Ultra-Violet Optical Telescope as conservative upper limits on the shock brightness. Comparing this limit with the predicted flux for various shock models, we constrain the geometry of the SN progenitor-companion system. We find the model of a 1 M{sub Sun} red supergiant companion in Roche-lobe overflow to be excluded at a 95% confidence level for most individual SNe for all but the most unfavorable viewing angles. For the sample of 12 SNe taken together, the upper limits on the viewing angle are inconsistent with the expected distribution of viewing angles for red gaint stars as the majority of companions with high confidence. The separation distance constraints do allow main-sequence companions. A better understanding of the UV flux arising from the SN itself as well as continued UV observations of young SNe Ia will further constrain the possible progenitors of SNe Ia.

THE COMPOSITE SPECTRUM OF BOSS QUASARS SELECTED FOR STUDIES OF THE Lyα FOREST

The Baryon Oscillation Spectroscopic Survey (BOSS) has collected more than 150,000

SPECTRAL EVOLUTION IN HIGH REDSHIFT QUASARS FROM THE FINAL BARYON OSCILLATION SPECTROSCOPIC SURVEY SAMPLE

2.1 \leq z \leq 3.5

Scaling Relations and Overabundance of Massive Clusters at Z ≳ 1 from Weak-Lensing Studies with the Hubble Space Telescope

quasar spectra since 2009. Using this unprecedented sample, we create a composite spectrum in the rest-frame of 102,150 quasar spectra from 800 \AA\ to 3300 \AA\ at a signal-to-noise ratio close to 1000 per pixel (

Spectral Evolution in High Redshift Quasars from the Final BOSS Sample

\Delta v