KICP Seminars: 2006

September 29, 2006 | 12:00, LASR Conference Room | Host: Angela V. Olinto
The Photometric Properties of the Most Massive, High-Redshift Galaxies
Brant Robertson, KICP
Note: Refreshments served at 3:15 pm
The presence of massive galaxies at high-redshifts (z>7) places constraints on hierarchical scenarios for the cosmological formation of structure. By combining high-resolution hydrodynamical simulations of the hierarchical formation of a redshift z~6 quasar, stellar population synthesis models, prescriptions for interstellar and intergalactic absorption, and the photometric response of modern telescopes, we calculate the observable properties of quasar progenitors at high-redshifts. The rapidly star-forming progenitors of z~6 quasars should be detectable using pre-existing photometric selection techniques like those used to identify distant galaxies in the Hubble Ultra Deep Field, but their low number densities will likely require future surveys of large portions of the sky.

October 6, 2006 | 12:00, LASR Conference Room | Host: Angela V. Olinto
Dark Matter in the Neutrino Sector: Sterile Neutrinos
Kevork Abazajian, UMD College Park
Hidden in the neutrino sector may be one or more fermions with no standard model interactions that nonetheless couple to neutrinos via their mass generation mechanism, namely sterile neutrinos. Such a particle may be the dark matter, produced in the early universe through matter-suppressed neutrino mixing or matter-enhanced resonant mixing. I will overview the kinetics of relativistic mixed neutrinos in dense environments, and will specify with sterile neutrino dark matter production in the early universe. I will discuss how this candidate alters cosmological structure formation and the resulting constraints from observed cosmological matter clustering. In addition, I discuss how this candidate may be detected by X-ray telescopes, as well as current constraints from X-ray observations.

October 13, 2006 | 12:00, LASR Conference Room | Host: Angela V. Olinto
Can We See Gravitational Waves from the End of Inflation?
Eugene Lim, Yale University
We show that, generically, the process of pre/reheating at the end of inflation is potentially a strong source of gravitational waves. We demonstrate numerically that, for a wide class of simple inflationary models, the gravitational wave energy density produced by such processes can be up to 5 orders of magnitude larger than the most optimistic predictions of the usual primordial gravitational wave spectra. This spectrum is scale-dependent, with its peak frequency inversely proportional to the square root of the scale of inflation. We show that for low scale inflation, this power spectrum is potentially detectable by the next generation GW detectors such as LIGO II.