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Astrophysics Seminars

Contents

The CASS Astrophysics Seminar features world-class astrophysicists from around the world speaking on current topics of research. Presentations are aimed at the graduate and post-graduate level, but are open to the general public. CASS seminars take place on Wednesdays from 4:00 - 5:00 p.m. in 383 SERF (Marlar Seminar Room), unless otherwise noted. You can watch a live stream of the talk or prior talks at the CASS Seminar YouTube Channel. The organizers are Prof. Shelley Wright and Prof. George Fuller.


Upcoming Seminars

Fall 2017

Winter 2018


January 10, 2018

 "Cosmology Through the Dust: Mitigating Galactic Foregrounds with HI"

Brandon Hensley
Postdoctoral Fellow
JPL

 Whether galaxy surveys in the optical or polarized CMB measurements in the microwave, cosmological observations are sensitive to contamination from Galactic dust. I will first present new, large scale maps of interstellar reddening constructed from the fully-sky, spectroscopic HI observations of the HI4PI Survey. Using atomic hydrogen as a tracer of Galactic dust eliminates the need for dust temperature corrections and allows easy removal of extragalactic contamination, producing reddening maps of higher fidelity than those based on far-infrared dust emission, such as that of Schlegel, Finkbeiner, and Davis 1998 ("SFD"). Given the ability of HI to serve as a template for the dust column, I will describe a novel method for using HI to make Cosmic Infrared Background (CIB) maps with high fidelity on large angular scales. Finally, I will discuss some possibilities for using HI and other ancillary data to constrain dust physics and ISM structure, enabling more effective component separation in CMB experiments.



January 17, 2018

 "Analysis of dust emission in nearby galaxies - Implications of the modeling
assumptions"

Jérémy Chastenet
Postdoctoral Scholar
UCSD-CASS

 My work focused on the implications of dust emission modelisation choices on its derived properties in nearby galaxies. A first approach showed that all models do not fit observations of two nearby galaxies adequately and similarly, although they all managed to fit the Milky Way infrared emission. It also highlighted that the dust composition is not the same between those two galaxies, and also with that of the Milky Way. The choice of the dust grains environment, through the incident radiation field, can significantly impact results like the total dust masses. A second project investigated the systematics errors due to the empirical laws used to describe theradiation field that heats the dust grains. I showed that some parameters can be over- or underestimated, while showing good fits to the observations. By getting rid of uncertainties due to dust composition, my results show that the current approach leads to discrepancies in the dust content in spite of a correct dust description.



January 24, 2018

Victor Robles
Postdoctoral Researcher
UC Irvine



January 31, 2018

 "Breaking the Habit - The peculiar 2016 eruption of the remarkable recurrent nova
in M31"

Martin Henze
Postdoc
San Diego State University

 Since its discovery in 2008, the Andromeda galaxy nova M31N 2008-12a has been observed in eruption every single year. This unprecedented frequency indicates an extreme object, with a massive white dwarf and a high accretion rate, which is the most promising candidate for the progenitor of a type-Ia supernova known to date. The previous three eruptions of M31N 2008-12a have displayed remarkably homogeneous multi-wavelength properties. In contrast, the delayed 2016 eruption (in December last year) showed significant deviations from this pattern. In this talk, I will discuss the 2016 observing campaign and its results, together with possible interpretations on the physics and evolution of this unique system in the context of extragalactic nova science.



February 7, 2018

NOTE: Joint Astro-Plasma Physics Seminar

Ellen Zweibel
W. L. Kraushaar Professor of Astronomy & Physics, Department of Astronomy
University of Wisconsin-Madison



February 14, 2018

Joy Didier
Postdoc
UC Santa Cruz



February 28, 2018

 "Closing in on Black Hole Spins"

John Tomsick
Researcher, Space Sciences Lab
UC Berkeley

 Determining how rapidly black holes (BHs) spin has been a key goal of astrophysics for decades. Knowing the spin rates of BHs is relevant to probing regions of strong gravity, understanding how relativistic jets are powered, and determining how BHs form and evolve. In this talk, I will discuss methods that have been developed for measuring the spins of accreting BHs with X-ray spectral and timing observations. This includes past X-ray timing and spectral measurements with RXTE, recent X-ray reflection measurements with the Nuclear Spectroscopic Telescope Array (NuSTAR), and future X-ray and soft gamma-ray polarization measurements with IXPE, XIPE, and COSI-X. Comparisons between spins of accreting stellar mass BHs and the constraints found by gravitational wave measurements for BH/BH merger events will also be presented.



March 7, 2018

Emily Pringle
Scripps Postdoctoral Fellow
UCSD-SIO



March 14, 2018

Gina Panopoulou
Staff Scientist, Radio Astronomy
Caltech


Spring 2018


April 25, 2018

Jorge Pineda
Research Scientist
JPL



May 9, 2018

Jessica Werk
Assistant Professor
University of Washington



May 23, 2018

Chung-Pei Ma
Professor of Astronomy and Physics
UC Berkeley



May 30, 2018

Ruth Murray-Clay
Professor
UC Santa Cruz