BCCP talks

Tuesday, October 28
Location: UCB, Hearst Field Annex B-1, 1:10 p.m.
Speaker: Joseph Clampitt, Penn
Title: “Lensing Measurements of SDSS Voids and Filaments”Abstract: I will describe measurements of weak lensing mass profiles of voids from a volume-limited sample of SDSS Luminous Red Galaxies (LRGs). The stacked shear measurement has been performed on ~10,000 voids and subvoids with radii between 15-40 Mpc/h and redshifts between 0.16-0.37. The characteristic radial shear signal of voids is detected with a statistical significance that exceeds 13-sigma. The mass profile corresponds to a fractional underdensity of about -0.4 inside the void radius and a slow approach to the mean density indicating a partially compensated void structure. Time permitting, I will also describe a stacked weak lensing detection of filaments between close pairs of LRGs.

Friday, October 31
Location: LBNL, 50-5026, 12 p.m.
Speaker: Liang Dai, JHU
Title: “Conformal Fermi coordinates and the local universe formalism”Abstract: In an inhomogeneous Universe, the physical effect of long-wavelength perturbation on short distances should be such that short-wavelength perturbations effectively evolve in a modified homogeneous universe. We explicitly construct the so-called conformal Fermi normal coordinates (CFNC) through an expansion around the observer’s geodesic, which describe the local spacetime as a quasi-FRW metric and are valid at all times. The CFNC formalism demonstrates that the zeroth-order picture is that local expansion rate and spatial curvature are renormalized by long-wavelength perturbations, and the general condition for the spatial curvature to be a constant is derived. Beyond this “separate universe” picture, CFNC allows for systematic extraction of additional local effects from long-wavelength perturbations that cannot be attributed to a re-definition of the background FRW cosmology. The formalism can be useful in the studies of tracer bias, intrinsic alignment and gravitational-wave “fossil” effect.


For future BCCP talks, see this page.

BCCP Workshop in January 2014

BCCP Workshop: 5th annual Essential Cosmology for the Next Generation Meeting

BCCP and the Instituto Avanzado de Cosmologia Mexico held the 5th annual Essential Cosmology for the Next Generation meeting January 13-17, 2014, popularly known as Cosmology on the Beach. The conference blends a winter school of lecture courses by world-leading scholars with plenary talks on hot research topics. This year, topics included CMB polarization, gravitational wave cosmology, particle physics, tests of gravity, and statistical and experimental methods.

For slides from the BCCP/IAC meeting Essential Cosmology for the Next Generation 2014 workshop, click here. They are also available on the Presentations Page.