MIT ASTROPHYSICS BROWN BAG LUNCH TALKS: One Two Quench: A Double Minor Merger Scenario & Disentangling the Causes and the Consequences of the [CII] Deficit
BBL 4/26/2021 — Speakers: Nicole Sanchez (University Of Washington) And Jessica Sutter (University Of Wyoming)
Monday April 26, 2021 12:00 pmvia Zoom
Nicole Sanchez, University of Washington
One Two Quench: A Double Minor Merger Scenario
Abstract: In this talk, I will discuss the effects of supermassive black hole (SMBH) feedback on the evolution of Milky Way-mass (MW-mass) galaxies. The galaxies I will present are drawn from the cosmological volume Romulus25, which uses the N-body+Smoothed particle hydrodynamics code, ChaNGa. To create a second set of simulations, I employ a novel technique called genetic modification (GM) to generate galaxies from nearly identical initial conditions resulting in minor modifications to their accretion histories that maintain the large scale structure and final main halo mass of the original simulation. This technique allows for a truly controlled experiment that can isolate specific physical processes that influence galaxy evolution. Exploring MW-mass galaxies from both of these simulation suites, we find that the combination of large scale galaxy accretion–in the form of minor merger interactions–and feedback from the SMBH can work in tandem to fully quench star formation.
Jessica Sutter, University of Wyoming
Disentangling the Causes and the Consequences of the [CII] Deficit
Abstract: The 158 micron emission line of singly ionized carbon has become a frequent choice for studies of the most distant galaxies. The long wavelength of this far-infrared fine structure line allows for passage through gas and dust with minimal attenuation and its ability to cool both the neutral and ionized phases of the ISM often make it the brightest observed emission line in star-forming galaxies. One potential shortcoming of the [CII] line is the effect known as the [CII] deficit, in which galaxies with increased star formation often see a drop in the ratio of [CII]-to-infrared luminosity. This decreasing ratio is a worrisome sign for the many programs that propose to use [CII] as an indicator of star formation rates. In order to overcome this obstacle and find the best uses for the slew of high-z [CII] detections, it is essential a complete understanding of the cause of this deficit is determined. In pursuit of this goal, observations of [CII] along with a full suite of panchromatic data from 28 nearby galaxies has been put to use. Based on preliminary results it seems the thermalization of the [CII] line in the ionized phases of the ISM is a major cause of the observed [CII] deficit.