Dark Matter and First Galaxies Light Up

Colloquium: Astronomy Colloquia | October 25 | 4 p.m. | 2 LeConte Hall

Speaker/Performer: Marusa Bradac, UC Davis

Sponsor: Department of Astronomy

The cluster of galaxies 1E0657-56 has been the subject of intense research in the last few years. This system is remarkably well-suited to addressing outstanding issues in both cosmology and fundamental physics. It is one of the hottest and most luminous X-ray clusters known, and is unique in being a major supersonic cluster merger occurring nearly in the plane of the sky, earning it the nickname "the Bullet Cluster". The newest HST/WFC3 data has revealed further interesting properties of this cluster. We have also studied a couple of new Bullet-like cluster, MACSJ0025-1222, A520, and DLSCL J0916.2+2951. Allthough they do not contain a low-entropy, high density hydrodynamical 'bullet', these clusters exhibits many similar properties to the Bullet Cluster.

Furthermore, the advent of Wide Field Camera 3 (WFC3) on HST enabled us to detect galaxies at z~7. They are likely beacons of the epoch of reionization, which marked the end of the so-called "Dark Ages" and signified the transformation of the universe from opaque to transparent. Clusters of galaxies, when used as cosmic telescopes, can greatly simplify the task of studying and finding these galaxies. With a massive cluster one can gain several magnitudes of magnification over a typical observing field, enabling imaging and spectroscopic studies of intrinsically lower-luminosity galaxies than would otherwise be observable, even with the largest telescopes. In this talk I will present the new spectroscopy results we have obtained with LRIS@Keck and FORS2@VLT to study these galaxies behind some of the most powerful cosmic telescopes and discuss our future goals with MOSFIRE@Keck and Spitzer.

Event Contact: rhelgens@astro.berkeley.edu, 510-642-5275