No Evidence for Dark Energy Dynamics from a Global Analysis of Cosmological Data (2009)
Serra, Paolo, Cooray, Asantha, Holz, Daniel E., Melchiorri, Alessandro, Pandolfi, Stefania, Sarkar, Devdeep
We use a variant of principal component analysis to investigate the possible temporal evolution of the dark energy equation of state, w(z). We constrain w(z) in multiple redshift bins, utilizing the...
Riess, Adam G., Macri, Lucas, Casertano, Stefano, Sosey, Megan, Lampeitl, Hubert, Ferguson, Henry C., ...
We report observations of 240 Cepheid variables obtained with the Near Infrared Camera (NICMOS) through the F160W filter on the Hubble Space Telescope (HST). The Cepheids are distributed across six...
Implications of Two Type Ia Supernova Populations for Cosmological Measurements (2008)
Sarkar, Devdeep, Amblard, Alexandre, Cooray, Asantha, Holz, Daniel E.
Recent work suggests that Type Ia supernovae (SNe) are composed of two distinct populations: prompt and delayed. By explicitly incorporating properties of host galaxies, it may be possible to target...
Weak Lensing of the Primary CMB Bispectrum (2008)
Cooray, Asantha, Sarkar, Devdeep, Serra, Paolo
The cosmic microwave background (CMB) bispectrum is a well-known probe of the non-Gaussianity of primordial perturbations. Just as the intervening large-scale structure modifies the CMB angular power...
Cosmic Shear from Scalar-Induced Gravitational Waves (2008)
Sarkar, Devdeep, Serra, Paolo, Cooray, Asantha, Ichiki, Kiyotomo, Baumann, Daniel
Weak gravitational lensing by foreground density perturbations generates a gradient mode in the shear of background images. In contrast, cosmological tensor perturbations induce a non-zero curl mode...
Lensing and Supernovae: Quantifying The Bias on the Dark Energy Equation of State (2007)
Sarkar, Devdeep, Amblard, Alexandre, Holz, Daniel E., Cooray, Asantha
The gravitational magnification and demagnification of Type Ia supernovae (SNe) modify their positions on the Hubble diagram, shifting the distance estimates from the underlying luminosity-distance...
Beyond Two Dark Energy Parameters (2007)
Sarkar, Devdeep, Sullivan, Scott, Joudaki, Shahab, Amblard, Alexandre, Holz, Daniel E., Cooray, Asantha
Our ignorance of the dark energy is generally described by a two-parameter equation of state. In these approaches a particular {\it ad hoc} functional form is assumed, and only two independent...
Current Status Of Velocity Field Surveys: A Consistency Check (2006)
Sarkar, Devdeep, Feldman, Hume A., Watkins, Richard
We present an analysis comparing the bulk--flow measurements for six recent peculiar velocity surveys, namely, ENEAR, SFI, RFGC, SBF and the Mark III singles and group catalogs. We study whether the...