Daniel L. Shafer

Chasing the phantom: A closer look at Type Ia supernovae and the dark energy equation of state

Some recent observations provide

Robust model comparison disfavors power law cosmology

> 2\sigma

Dark energy two decades after: observables, probes, consistency tests

evidence for phantom dark energy -- a value of the dark energy equation of state less than the cosmological-constant value of

Principal components of dark energy with Supernova Legacy Survey supernovae: The effects of systematic errors

-1

No evidence for bulk velocity from type Ia supernovae

. We focus on constraining the equation of state by combining current data from the most mature geometrical probes of dark energy: Type Ia supernovae (SNe Ia) from the Supernova Legacy Survey (SNLS3), the Supernova Cosmology Project (Union2.1), and the Pan-STARRS1 survey (PS1); cosmic microwave background measurements from Planck and WMAP9; and a combination of measurements of baryon acoustic oscillations. The combined data are consistent with

Testing ΛCDM at the lowest redshifts with SN Ia and galaxy velocities

w = -1

Multiplicative errors in the galaxy power spectrum: self-calibration of unknown photometric systematics for precision cosmology

for the Union2.1 sample, though they present moderate (

of current systematic errors in Type Ia supernova (SN Ia) measurements on dark energy (DE) constraints using current data from the Supernova Legacy Survey (SNLS). We consider how SN systematic errors aect constraints from combined SN Ia, baryon acoustic oscillations (BAO), and cosmic microwave background (CMB) data, given that SNe Ia still provide the strongest constraints on DE but are arguably subject to more signicant

\sim 1.9\sigma

Baryons inQCDASat largeNc: A roundabout approach

) evidence for a phantom value when either the SNLS3 or PS1 sample is used instead. We study the dependence of the constraints on the redshift, stretch, color, and host galaxy stellar mass of SNe, but we find no unusual trends. In contrast, the constraints strongly depend on any external

Baryons in QCD_{AS} at Large N_c: A Roundabout Approach

H_0