| Abstract: Dennis Zaritsky
"How to See the Circumgalactic Medium”
Ann Zabludoff
Title:
Hearts of Darkness: Rethinking the Role of Supermassive Black Holes in Galaxy Evolution
Abstract:
While astronomers are working hard to detect the earliest galaxies and to follow their evolution, we remain baffled by the present-day dichotomy between disky, star forming galaxies and quiescent, spheroidal galaxies. The key is to find galaxies in transition from one class to the other, whose spectra indicate intense recent star formation that has now ended. We have identified thousands of such "post-starburst galaxies" whose current kinematics, stellar populations, and morphologies are consistent with late- to early-type galaxy evolution. I will discuss recent work that suggests new connections between their violent merger history and the central supermassive black hole. For example, the molecular gas reservoir of a post-starburst galaxy declines rapidly after the starburst ends and in a manner consistent with feedback from an active nucleus. Furthermore, a star is ~300x more likely to be tidally disrupted by the nucleus of a post-starburst galaxy than in other galaxies. Like the well-known black hole-bulge mass correlation, these surprising links between the properties of a galaxy on kpc scales and its nucleus on pc scales require explanation.
and bonus peak at:
Title:
Attack of the Lyman-Alpha Blobs: A Multi-Wavelength and Polarization Study
Abstract:
Lyman-alpha blobs are mysterious gas clouds in the distant Universe that extend to tens or even hundreds of kpc. We have shown that blobs occupy massive halos likely to evolve into rich groups and clusters of galaxies today. As such, blobs also mark the sites of the formation of the most massive galaxies and of the intracluster medium. While blobs are exciting tracers of large-scale structure formation and evolution, their power source remains a puzzle. To address it, we have developed new instrumental capabilities and data analysis techniques. Now we are combining measurements of blob surface density, gas kinematics, and, uniquely, 2D polarization with radiative transfer models to identify the configuration and sources of the Lyman-alpha emission. These results represent a different path toward understanding the illumination of structures in the early universe. |