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Astrophysics Seminars


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

Winter 2018

January 17, 2018

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

Jérémy Chastenet
Postdoctoral Scholar

 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 19, 2018

NOTE: Special Lecture from 3:00-5:00PM in SERF 383
 "Dark Matter Decay According to Conformal Cyclic Cosmology: Does it Provide
Detectable Gravitational Signals?"

Sir Roger Penrose
Oxford/Penrose Institute

 In the cosmological scheme of conformal cyclic cosmology (CCC), the equations governing the crossover form each aeon to the next demand the creation of a dominant new scalar material, postulated to be dark matter. In order that this material does not build up from aeon to aeon, it is taken to decay away completely over the history of each aeon. The dark matter particles (erebons) may be expected to behave almost as classical particles, though with bosonic properties, being probably of about a Planck mass, and interacting only gravitationally. Their decay would be to gravitational signals, and responsible for the (~scale invariant) temperature fluctuations in the CMB of the succeeding aeon. In our own aeon, erebon decay might well show up in signals discernable by gravitational wave detectors.

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
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
 "The Basis for Cosmic Ray Feedback: Microscales to Macroscales"

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

 Cosmic rays, mostly relativistic protons, represent less than a billionth of interstellar particles, but comprise roughly the same energy density as the thermal gas. Their interaction with the thermal gas is primarily collisionless, mediated by the ambient magnetic field. I will discuss the plasma physics that underlies this interaction, and how it allows cosmic rays to sculpt, or feed back on, their environments.

February 14, 2018

Joy Didier
UC Santa Cruz

February 21, 2018

Rene Ong
Professor, Department of Physics and Astronomy

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

March 14, 2018

Gina Panopoulou
Staff Scientist, Radio Astronomy

Spring 2018

April 25, 2018

Jorge Pineda
Research Scientist

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
UC Santa Cruz