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Journal Club Seminars From 2017 - 2018

Contents


FALL 2017


October 6, 2017

NOTE: CASS All-Hands Meet & Greet

 CASS All-Hands Meet & Greet this Friday, October 6, from 12:00 to 1:00 pm in SERF 383. This meeting will be an opportunity for new members of CASS to introduce themselves and present a quick overview of their research. It will also give established members of CASS a chance to summarize their recent work. New graduate students are especially encouraged to attend. Pizza and soda will be provided. Journal Club is an informal environment in which graduate students can give short talks on any subject of interest to them, be it a recent paper, their own research, or any other topic. Talks will resume next week. All are welcome to attend.



October 13, 2017

 "On the Molecular Gas Content of z~1 Galaxies and the Origin
of Ultra-Diffuse Galaxies"

Timothy Carleton (12:00-1:00)
PhD Candidate
UC Irvine

 I will present results from two projects investigating two different puzzles in galaxy evolution.

First, I will address the question of why star-formation rates in z~1 galaxies are elevated compared with their z~0 counterparts: is this a result of an increased supply of molecular gas to galaxies or a more efficient conversion of existing molecular gas into stars? With new sensitive mm and sub-mm facilities such as PdBI and ALMA, we are able to directly probe signatures of the molecular gas reservoir in high-z galaxies; however, extracting a measurement of the molecular gas content of these objects relies on an uncertain conversion from the observed tracer (typically Carbon Monoxide) luminosity to the molecular gas gas mass. Motivated by the dependence of this conversion factor (alpha_CO) on ISM properties observed locally, I will present an investigation of the variation between alpha_CO and integrated galaxy properties, in particular mass surface density, in 38 massive star-forming galaxies at z~1. Overall, I find that the molecular gas conditions at z~1 are remarkably consistent with those at z=0, suggesting that the process of converting molecular gas to stars in z~1 galaxies is similar to that identified in local galaxies.

Additionally, I will discuss a model for the formation of Ultra-Diffuse Galaxies (UDGs). These dwarf galaxies, with half-light radii similar to that of the Milky Way, but only 1% of its stellar mass, present a significant challenge to our understanding of dwarf-galaxy evolution. Motivated by the environmental dependence of UDG abundance, I investigate the effects of tidal stripping on the dwarf galaxy population using a semi-analytic model for the influence of tidal-stripping on the stellar mass and half-light radius of dwarf galaxies applied to dark-matter halos in the Bolshoi simulation. In particular, simulations show that dwarf galaxies occupying cored dark-matter halos expand significantly as a result of tidal heating as they pass through a massive cluster. By applying this relatively simple model, I am able to reproduce the observed stellar mass and half-light radii distributions of UDGs, as well as the observed UDG abundance across a range of environments remarkably well.



October 20, 2017

NOTE: Journal Club Cancelled Today



October 27, 2017

NOTE: Safe and Healthy Work Space: Harassment Discussion

 Discussion will take place this Friday, October 27 from 12:00-1:00 pm in SERF 383. Pizza and soda will be provided.



November 3, 2017

Alessondra's Title: "Radar Love: Recent Asteroid & Comet Results from Arecibo
Observatory's Planetary Radar System"
Gene's Title: "Recent variability of the changing-look AGN Mrk 1018"

Alessondra Springmann (12:00-12:30)
Visiting Graduate Student @ UCSD-CASS
University of Arizona
Gene Leung (12:30-1:00)
Physics Graduate Student
UCSD-CASS

Alessondra's Abstract: Asteroids do concern me, Admiral: short of sending spacecraft to an asteroid, the best way to learn about asteroids is to zap them with radar. Arecibo Observatory in Puerto Rico is home to the world's largest single-dish radio telescope and the most powerful planetary radar system for asteroid studies. The 305-meter diameter facility dedicates hundreds of hours a year to improving our knowledge of near-Earth asteroids and comets with planetary radar. Radar observations reveal a wide variety of asteroids shapes, surface features, and sizes, as well as asteroid moons. Important not only for robotic solar system exploration of asteroids, radar-derived asteroid shape models help us plan for potential asteroid hazard mitigation and future human exploration of asteroids. I will show recent results from the Arecibo planetary radar system and discuss the upcoming asteroid sample return mission OSIRIS-REx that launched in September 2016 to bring pieces of an ancient asteroid to Earth.



November 10, 2017

NOTE: No Journal Club Today - Veteran's Day Holiday



November 16, 2017

NOTE: Journal Club Today (instead of tomorrow)
Logan's Title: reviewing the paper “Axion Gauge Field Inflation and Gravitational Leptogenesis: A Lower Bound on B Modes from the Matter-Antimatter Asymmetry of the Universe"
<https://arxiv.org/abs/1706.03765v2>
Tucker's Title: reviewing the paper "Search for Neutrinoless Double-Beta Decay of 130Te with CUORE-0”
<https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.115.102502>

Logan Howe (12:00-12:30)
Physics Graduate Student
UCSD-CASS
Tucker Elleflot (12:30-1:00)
Physics Graduate Student
UCSD-CASS



November 24, 2017

NOTE: No Journal Club Today - Thanksgiving Holiday



December 1, 2017

 "Deep Learning for Galaxies"

Joel Primack (12:00-1:00)
Distinguished Professor of Physics Emeritus
UC Santa Cruz



December 8, 2017

Marie Wingyee Lau (12:00-1:00)
PhD Candidate
UC Santa Cruz



WINTER 2018

SPRING 2018