Physics Speaker Tour 2020-02-04T14:50:56+00:00

2019-2020 Physics Speaker Tour

Dr. Gregory R. Sivakoff
University of Alberta

Feb. 2:  MUN
Feb. 4: SMU
Feb. 5: Acadia
Feb. 6: StFX
Feb. 7: UPEI

Winds of Change around Black Holes

Accretion disks, where matter with angular momentum spirals down through a disk, occur around objects ranging from the youngest stars to supermassive black holes. But not all of this material reaches the center of the disk. Instead, some material is accelerated away from the disk. These outflows can be ejected in a narrow opening angle (what astronomers call “jets”) or can be relatively unfocused (what astronomers call “winds”). While we do not know the precise processes that accelerate and collimate winds and jets, magnetic fields almost certainly play a key role. My team and I study black hole X-ray binaries, stellar-mass black holes accreting from a nearby star. We combine observations across the electromagnetic spectrum to learn about the physics of accretion and jets. In this talk, I will discuss how we have revealed two new windows onto the physics of inflows and outflows in X-ray binaries: fast variability measured across the electromagnetic spectrum (which provides the potential to accurately identify the accretion physics that launch relativistic jets) and the modelling of changes in the X-ray brightness of black hole X-ray binaries (which implies that strong winds from the accretion disk are universal). With the advent of new and upcoming facilities, we have a huge potential to take advantage of these winds of change in the next decade.


Dr. Gregory Sivakoff is currently an Associate Professor in the University of Alberta Department of Physics, where he has been a faculty member since 2011. He and his group’s primary research focuses on multi-wavelength observations of compact objects (white dwarfs, neutron stars, and black holes), tying together a wide range of data to better probe important physics around compact objects. These multi-wavelength observations stretch across nearly the entire electromagnetic spectrum, and are made by facilities across the world and above it. Two classes of objects stand out among the wide range of compact objects he studies: X-ray binaries, neutron stars or black holes that accrete material from a nearby donor star; and the relativistic outflows (jets) from supermassive black holes that are responsible for (at least some) astrophysical neutrinos that have recently been detected. Dr. Sivakoff also has strong interests in Education & Public Outreach; in addition to his multiple pop-culture inspired public talks like, “Black Holes and Revelations” and “Fantastic Black Holes and How to Find Them”, he is a strong advocate of citizen science. This support includes sitting on the board of the American Association of Variable Star Observers, an international non-profit organization of variable star observers whose mission is to enable anyone, anywhere, to participate in scientific discovery through variable star astronomy. In 2018 he was selected as the inaugural Telus World of Science Edmonton Science Fellow, which recognizes an outstanding researcher or innovator based in Northern Alberta, and was the recipient of the University of Alberta Faculty of Science Research Award.

Dr. Kris Poduska
Memorial University of Newfoundland

March 30: MtA
March 31: UNB
April 1: UdeM

How physics helps to simulate a search for life on Mars

Mars-based life could exist in the form of microbes that get their energy from interactions between water and certain kinds of subsurface rock. However, detecting the telltale signatures of such microbes while they are still on Mars is an epic challenge. This talk will describe physics that helps make remote detection of such microbial activity more feasible. The key is detecting and differentiating reflected light, using a combination of infrared and visible wavelengths. We use data from satellites, as well as from drones equipped with specialized cameras, to tackle this complex puzzle that has many technical constraints. You’ll see how our interdisciplinary team, from academia and industry, puts all of this together to simulate a microbe-detection mission on Mars-like terrain that exists right here in Canada.


Kris Poduska is an experimental condensed matter physicist based at Memorial University of Newfoundland, where she has been on the faculty in the Department of Physics & Physical Oceanography since 2003. Originally from the United States, Dr. Poduska holds an undergraduate degree in physics from Carleton College (Northfield, Minnesota, USA), and a Ph.D. in physics from Cornell University. Her research is a blend between physics and chemistry, focusing on understanding structural and physical property relations in inorganic materials. The applications of the work span from technologically relevant semiconductors, to medically interesting biomaterials, to ancient archaeological materials.