Colloquia
Colloquia & Current Events 2024 - 2025
Colloquia Abstracts
SUBJECT TO CHANGE! Be sure to check back often
A&P Colloquium series
To obtain the Zoom link for any online event, please email the Astronomy and Physics Department Secretary, Shannon Rhode, at s.rhode@smu.ca. Colloquia are not recorded.
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What the Variability of Embedded Protostars Tells Us about Accretion: Past, Present, and Future
Doug Johnstone
Date: Friday 29 November 2024
Time: 3 pm
Venue: AT101
The James Clerk Maxwell Telescope (JCMT) has been monitoring eight nearby low-mass star-forming regions in the Gould Belt at submillimetre wavelengths for over seven years to search for and quantify the time dependent brightness variability of the resident deeply embedded protostars. Secular variability is common among these protostars; greater than 25% of the sample show measurable long-term brightness changes and 10% show burst behaviour lasting months to years. We interpret this secular variability as reflecting changes in the mass accretion rate from the disk to the protostar, as predicted by theoretical models of (proto)stellar assembly. For a subset of our sample we have contemporaneous mid-IR light-curves which allow additional constraints on the conditions responsible for the brightness variations, confirming that the submillimetre variability is driven by changes in the dust temperature profile of the envelope. Furthermore, we have combined, for one source, single dish and interferometric sub-mm monitoring, which has allowed us to unambiguously recover a time lag in the variability at larger angular scales and use the results to confirm the envelope structure surrounding the embedded protostar.
Dr C Garraffo
Date: Friday 4 April 2025
Time: 3 pm
Venue: AT101
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Wilfred Buck
Please join the Department of Astronomy & Physics as we host a special colloquium screening of Wilfred Buck, a Top 5 Audience Favourite at the Hot Docs Canadian International Documentary Festival (2024)
Date: Friday 22 November 2024
Time: 2:30 pm
Venue: AT101
He’s from the “fresh-out-of-the-bush, partly civilized, colonized, displaced people,” and he’s here to take us to the stars. Lisa Jackson’s portrait of Cree Elder Wilfred Buck moves between earth and sky, past and present, bringing to life ancient teachings of Indigenous astronomy and cosmology to tell a story that spans generations. Adapted from Buck’s rollicking memoir I Have Lived Four Lives, the film weaves together stories from his life, including his harrowing young years of displacement and addiction. Seamlessly fusing present-day scenes with cinematic re-enactments and archival footage, this intimate yet expansive documentary takes us on an inspiring journey to the space beyond, and to the spaces between us all.
Date: Friday 15 November
No Colloquium
Fall Break
Material innovations for stable efficient photovoltaics
Ghadad Koleilat
Date: Friday 8 November 2024
Time: 3 pm
Venue: AT101
Solution processed semiconductors offer the advantage of low cost large scale applications such as in photovoltaics. To enable wider adoption, efficiency, reliability and stability of these new material systems need to be improved. The Koleilat group works in advanced materials innovation to accelerate adoption of alternative technologies. Dr. Koleilat will be presenting various material systems her group is working on and their applications in photovoltaics.
From Physics to Finance – Riding the Wave of Adventure
Alyson Bailey-Flynn (Royal Bank of Canada)
Date: Friday 1 November 2024
Time: 3 pm
Venue: AT101
As SVP, Capital Markets, Wealth Management, Insurance, APAC & Europe, Internal Audit at RBC Alyson has had a distinguished career in financial services across the multiple lines of defence, continents, and financial institutions. What started with a single physics class at Saint Mary’s, to a BSc Honours in Physics & Math, and eventually a Masters of Mathematical Finance, Alyson will share her journey and insights for success across her career.
Experimental Methods for Nuclear Astrophysics
Ben Reed (TRIUMF & Saint Mary's University)
Date: Friday 25 October 2024
Time: 3 pm
Venue: AT101
Understanding the origins of elements and the processes governing astrophysical environments requires precise knowledge of nuclear reaction rates. This talk explores both direct and indirect experimental methods used to study key nuclear reactions relevant to astrophysical phenomena. It highlights direct measurements conducted at TRIUMF with DRAGON and the development of the DEMAND Array, which introduces a novel experimental method for probing nuclear physics in core-collapse supernovae. Additionally, studies using Gammasphere for gamma-ray spectroscopy are discussed, offering crucial insights when direct measurements are not feasible. Together, these methods help refine models of stellar environments, contributing to a deeper understanding of nucleosynthesis and the evolution of the cosmos.
Simulating Cosmic Reionization
Rahul Kannan
Date: Friday 18 October 2024
Time: 3 pm
Venue: AT101
The study of primitive stars and galaxies is an exciting new frontier in astrophysics and cosmology. They form within the first gigayear after the Big Bang and significantly impact their surroundings by emitting a lot of high-energy radiation that transforms the surrounding cold neutral gas into a hot and ionized medium. This process, called reionization, is initially patchy, with ionized bubbles surrounding the most energetic sources. These bubbles eventually grow bigger and more numerous as the ionizing radiation output from galaxies increases and eventually overlap, ionizing the low-density gas in the entire Universe. Understanding this early epoch is important because it forms an important evolutionary link between the smooth matter distribution at early times and the complex structures we see today. Fortunately, a wide array of instruments that have been specifically designed to study the high redshift Universe, such as JWST, ALMA, HERA, and others, are unleashing a flood of observational data that is ushering the study of reionization into a new high-precision era. It is, therefore, imperative that theoretical/numerical models achieve sufficient accuracy and physical fidelity to meaningfully interpret these new results. In this talk, I will review the recent THESAN simulation project, which aims to self-consistently model the reionization process and the sources responsible for it.
Caffe AP
Date: Friday 11 October 2024
Time: 3 pm
Venue: AT 101
Galaxy Simulations in the Era of Exascale
Evan Schneider (University of Pittsburg)
Date: Friday 4 October 2024
Time: 3 pm
Venue: SB260 - Remote
Over the last several decades, galaxy formation theory has adopted "feedback" as an essential process affecting galaxy evolution. Winds generated by supernova explosions of massive stars are predicted to eject large quantities of mass and energy from the interstellar medium over cosmic time, regulating galaxy growth rates and polluting the CGM and IGM with heavy elements. However, our current observational and theoretical constraints on the amount of mass and energy ejected by these winds are uncertain by orders of magnitude. In this talk, I will describe our group’s efforts to better understand the physics of supernova-driven outflows using extremely high resolution simulations. Employing the GPU-based code Cholla on the world’s fastest computers, we can capture the effects of individual explosions on galaxy scales, allowing us to link predictions made by small-scale idealized simulations to halo-scale zooms with a cosmological context.
The SCALES project: Stirring up the ISM with clustered feedback
Marta Reina-Campos
Date: Friday 27 September 2024
Time: 3 pm
Venue: AT101
Stellar clusters are critical constituents within galaxies. Gravitationally-bound stellar systems are the result of intense star formation, and they regulate the baryonic lifecycle of their host galaxy through their clustered stellar feedback. However, current modern simulations of galaxy formation lack a holistic view of the role of star clusters in galaxy evolution, and how they are shaped by their host galactic environment.
In this seminar, I will review current numerical approaches to model the intertwined evolution of star clusters and galaxies, and I will discuss their perks and caveats. As an alternative approach, I will present a novel method to model individual star clusters within galaxies within the hydrodynamical code GIZMO. By employing sink particles, I can represent stellar clusters built via gas accretion and hierarchical merging with sub-clusters. Using a large grid of turbulent clouds, I will discuss the impact of a variety of numerical choices, and the consequences on the most massive star cluster of assuming different physical setups for the clouds. I will demonstrate that this prescription leads to molecular clouds being shorter lived due to more destructive feedback, and I will discuss what physics are required to reproduce the formation of star cluster populations.
Machine learning: A new data analysis paradigm for astrophysical data analysis
Yashar Hezvah
Date: Friday 20 September 2024
Time: 3 pm
Venue: AT101
In this talk I will share our research in analyzing strong gravitational lensing data for the inference of cosmological parameters. In particular I will discuss the shortcomings of traditional closed-form approaches to likelihoods and priors and show how machine learning can be used to perform significantly more accurate inference. I will discuss topics related to diffusion models, out-of-distribution issues, quantification of model accuracy and show how machine learning can be used within a rigorous Bayesian framework for the analysis of astrophysical data.
From General Relativity to General Partner in a Venture Capital Fund
Andrew Ray
Date: Friday 13 September 2024
Time: 3 pm
Venue: SB260
How I went from studying Astrophysics at Saint Mary’s to building spacecraft and startups. A survey by the American Institute of Physics found that 46% of recent physics PhD grads wanted to work in academia, yet less than 5% ended up doing so. Are physicists really that bad at math or is something else going on? In this session we’ll talk about maximizing the value that physicists can provide to the world and to themselves. It will cover my career spanning real world applications of General Relativity, my transition to startup founder (x3), and then to a science focused Venture Capital investor (where the math gets even simpler). It will touch on my experiences with startups and how they can maximize the impact of scientific discoveries for the world while also positioning scientists to share in the economic value created.