Events

In late June 2021, the Pacific Northwest experienced extraordinarily high temperatures. British Columbia alone recorded over 60 record high temperatures, with the town of Lytton setting an all-time high temperature in Canada for three consecutive days, peaking at 49.6 C (121.3 F). During this talk, we will explore the meteorological conditions that led to these extreme temperatures—analyzing the upper air dynamics, mid-level thermal anomalies, and terrain effects during the event. We will also delve into the societal and environmental impacts regionally.

Metallicities and elemental abundances are key to testing our current understanding of galaxy formation and evolution. At the beginning of the universe only light elements such as hydrogen and helium were produced. Carbon and heavier elements were instead created inside stars and distributed into the interstellar medium by stellar winds and supernova explosions. From the spatial distribution of elements in stars and gas, it is therefore possible to constrain the star formation and chemical enrichment histories of galaxies.

The Kepler telescope detected thousands of exoplanets in hundreds of multi-planet systems and revolutionised planetary sciences. Many of these systems are quite compact and are typically a few billions of years old. Consequently, we are seeing only a snapshot of system architectures after hundreds of billions or even trillions of orbits. A substantial portion of their evolution has been governed by dynamical interactions, however. This can allow us to probe their histories and constrain the role of the natal environment.

It has long been assumed that gravity and quantum mechanics can only be confronted at very high energies ~ 1.2 x 10^28 eV (enough to boil 5 tons of water, and 15 orders of magnitude above the range of particle accelerators). However, recent theory indicates that gravity may cause a breakdown of quantum mechanics at much lower energies, for large masses. This has led to a new experimental field in which such a breakdown is sought in earth-based labs.

How and why galaxies grow in stellar mass and cease their star formation are key open questions of galaxy formation and evolution. I present evidence for a diversity of pathways for building up the quiescent galaxy population at early cosmic times. Specifically, I will present observational constraints on star-formation histories and quenching timescales by combining Keck DEIMOS spectroscopic data with >10-band photometry.

The advent of Gaia and of large photometric and spectroscopic surveys is changing the landscape of white dwarf studies. These incredible new data sets, together with improved models, have enabled tackling some unsolved mysteries concerning white dwarfs as a population, as well as discovering extremely peculiar objects that challenge our understanding of white dwarf formation and evolution.

An important and unresolved question in cosmology today is whether there is new physics that is missing from our current standard Lambda Cold Dark Matter (LCDM) model.

Abstract:
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a drift-scan radio telescope designed to map large scale structure in the universe using the redshifted 21 cm line emitted by neutral hydrogen. By observing the 400 to 800 MHz frequency band, CHIME will measure the expansion rate of the universe in the redshift range z = 0.8 - 2.5 to constrain the nature of dark energy.

Because they are dark-matter dominated, dwarf galaxies provide some of the most stringent tests of our cold dark matter model. Specifically, Lambda CDM makes predictions about the number, shape, and spatial distributions of the faint friends of massive galaxies. I will present results from the Exploration of Local VolumE Satellites (ELVES) survey, that constructs the largest sample of satellites around Milky Way-like hosts.

Abstract:

A key open question in extragalactic astronomy is understanding the processes driving the build-up and quenching of massive galaxies — specifically the role of AGN and environment therein.

The Equity & Inclusion in PHAS team presents “Impostor Syndrome,” a workshop run by astrophysicist Dr. Renée Hložek.

Navigating the academic environment can be stressful. Power dynamics can impact our ability to communicate clearly with each other, and can generate feelings of impostor syndrome. In this interactive workshop, we will use techniques of improvisation and changing power dynamics to explore ways we can shape our communication environment.

Diffusion-weighted Magnetic Resonance Imaging (MRI) Depicts Regions of Sub- and Super-diffusion Encoded by the Fractional Diffusion Equation

We perform covariant quantization of Einstein gravity in spherical harmonic basis in the background of a Schwarzschild black hole. We use Regge-Wheeler gauge for modes with l>=2, and propose the gauge for l<2 modes.

Feedback from active galactic nuclei (AGN) is thought to be key in shaping the life-cycle of host galaxies. AGN inject a significant amount of energy into the surrounding interstellar medium and launch gaseous winds. They are therefore able to potentially suppress or inhibit future star formation in their hosts. An ideal cosmic laboratory to study how AGN regulate galaxy growth is the so-called cosmic noon (z~2), i.e. the peak of AGN accretion activity when their energy output is overall maximized.

Multi-wavelength observations, from the ultraviolet (UV) to the infrared (IR) and beyond, are powerful tools for exploring evolved stars and characterizing exoplanets. Cool evolved stars contribute significantly to the interstellar medium (ISM) enrichment, via gas and dust produced in their atmospheres. Yet, a thorough understanding of their mass loss mechanism(s) remains challenging. Exploring cool evolved stars' upper layers is thus essential to unraveling their mass loss history and its influence on the composition of the ISM and Galactic ecology.

It's Canada Day and we're not having a Departmental Colloquium!