Events List for the Academic Year
Event Time:
Monday, March 20, 2023 | 3:00 pm - 4:00 pm
Event Location:
HENN 318
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2023-03-20T15:00:00
2023-03-20T16:00:00
Illuminating Dark Halos with Gravitational Lensing
Event Information:
Abstract:
Gravitational lensing is a powerful cosmic tool for exploring a wide range of astrophysical phenomena including understanding how ordinary and dark matter couple and finding the earliest galaxies and stars. Using Convolutional Neural Networks to sift through legacy imaging data-sets, the AGEL survey confirms about 100 strong gravitational lenses that identify halos spanning a wide range in total mass and cosmological distance. I provide an overview of the AGEL survey and describe AGEL projects based on observations from the Hubble Space Telescope, Keck Observatory, and the Very Large Telescope.
Bio:
I joined the UNSW faculty in 2017 and have been a professional astronomer for 20+ years. I also was a professor at the University of Zürich and Texas A&M University. I received my PhD in Astronomy & Astrophysics from the University of California, Santa Cruz and I held postdoctoral fellowships at the Harvard-Smithsonian Center for Astrophysics, Leiden Observatory, and ETH Zürich. I have given 180+ presentations at universities and conferences around the world
Learn More:
See Kim-Vy's faculty webpage here
Event Location:
HENN 318
Event Time:
Thursday, March 16, 2023 | 4:00 pm - 5:00 pm
Event Location:
HENN 201
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2023-03-16T16:00:00
2023-03-16T17:00:00
Biophysics in latent space
Event Information:
Abstract:
Many phenomena in biology are considered too complicated or too contingent to be captured by predictive theories similar to what is done in physics. But complex systems theory has taught us that simple, higher level laws with few effective parameters can emerge from the interaction of small scale components. As biology is becoming more and more quantitative, one can use a combination of first-principle theoretical modelling with simple machine learning techniques to build accurate and tractable theories of biological dynamics. Those dynamics can often be best understood in (abstract) latent spaces, giving « physics-like » intuition.
I will illustrate the power of such approaches on a couple of biological examples, with a special focus on the dynamics of the adaptive immune system (T cells response). Our approach leads to applications in cancer immunotherapy that I will briefly describe.
Bio:
Paul François is a Professor of Bioinformatics at the Université de Montréal and an associate member of MILA, an AI research institute in Quebec. He earned his PhD from Université Paris in 2005, and today is a leading expert in theoretical and computational biophysics. His team applies machine learning approaches to explore an array of biophysics topics, including systems biology, developmental biology, evolution, and quantitative immunology. Among other accolades, Prof. François was awarded the Rutherford Memorial Medal in Physics by the Royal Society of Canada in 2019 and the CAP Herzberg Medal in 2017.
Learn More:
See Paul's faculty research page here
See the François group website here
Event Location:
HENN 201
Event Time:
Thursday, March 16, 2023 | 2:00 pm - 3:00 pm
Event Location:
HENN 318
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2023-03-16T14:00:00
2023-03-16T15:00:00
Classifying topological quantum pumps
Event Information:
Abstract:
In his seminal work, Thouless considered the evolution of a non-interacting electron gas under periodic driving and showed that the charge transported in a cycle is quantized provided the Fermi energy remains in a spectral gap throughout the evolution. In this talk, we will consider periodic transformations of states of locally interacting matter, which are both invariant under a compact group G and short range entangled. I will explain that a quantized $G$-charge is pumped during each cycle. Moreover, the pumping is stable under deformations of the loops, and two loops pumping the same charge can be deformed into each other. I will further relate this work to the classification of symmetry protected states.
Event Location:
HENN 318
Event Time:
Thursday, March 16, 2023 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2023-03-16T11:00:00
2023-03-16T12:00:00
Structuring light to reveal the invisible
Event Information:
Abstract:
From quantum physics to cosmology, researchers aim to “see” things which are typically invisible – be it the entanglement of two particles or infrared signatures from space. In these and various other fields, we are confronted by a common challenge: What we can see with our own eyes or observe using standard optical imaging systems is limited to a small fraction of the information that the detected light actually carries. Two-dimensional (2D), flat images, such as a photo, only reveal the intensity and visible color of the light coming to us from an optical scene. However, light contains a wealth of information on the three-dimensional (3D) position, angle of incidence, spectral context, amplitude, phase, polarization, optical angular momenta, coherence, amongst others. In fact, if light interacts with media, nature will give us structured light that is spatially varying in the named properties in a fashion that depends on the interaction. In this talk, I will present how we can use these kinds of structured light fields to extract information from an optical scene and, vice versa, how structured light can serve as an excitation or probing tool to gain access to usually invisible information. In this context, we will explore “optical vortices” in phase and polarization, their generation, and application. Moreover, we will gain insights into the nanoscale features of structured light and its leading role for next-generation imaging techniques.
Bio:
Eileen Otte is a postdoctoral researcher in Prof. Mark Brongersma’s group at Stanford University, USA. After her undergraduate studies and completing her Master degree with distinction, she specialized on structured singular light in her PhD studies. She performed her research at the University of Muenster (WWU), Germany, as well as the University of Witwatersrand, South Africa, under the supervision of Prof. Dr. Cornelia Denz and Prof. Dr. Andrew Forbes. In 2019 she finished her PhD, honored with "summa cum laude" and the WWU Dissertation Award in Physics, and published in the Springer Theses series. Further, she received the Research Award 2020 of the Industrial Club Duesseldorf and was accepted as a junior class member of the NRW Academy of Sciences, Humanities, and the Arts. After her PhD, Eileen performed research on complex topological structures in light and light-matter-interaction, including new structured-light-based sensing approaches. Since 2021, at Stanford and in collaboration with the Center for Soft Nanoscience (WWU), she concentrates on imaging nano-scale emitters using metasurfaces. Supporting her research, Eileen was awarded the GLAM fellowship (Stanford University) as well as the PRIME fellowship (DAAD, Germany).
Learn More:
See article on Eileen's research and funding award from the DAAD program here
Event Location:
HENN 318
Event Time:
Thursday, March 16, 2023 | 10:00 am - 11:00 am
Event Location:
AMPL 311
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2023-03-16T10:00:00
2023-03-16T11:00:00
Semiconductor Quantum Dots
Event Information:
Abstract: Semiconductor nanostructures with low dimensionality like quantum dots are one the best attractive solutions for achieving high performance photonic devices. When one or more spatial dimensions of the nanocrystal approach the de Broglie wavelength, nanoscale size effects create a spatial quantization of carriers along with various other phenomena based on quantum mechanics. Thanks to their compactness, great thermal stability and large reflection immunity, semiconductor quantum dot lasers are very promising candidates for low energy consumption and isolation free photonic integrated circuits. When directly grown on silicon, they even show a four-wave mixing efficiency much superior compared to the conventional quantum well devices. This remarkable result paves the way for achieving high-efficiency frequency comb generation from a photonic chip. Quantum dot lasers also exhibit a strong potential for applications in optical routing and optical atomic clock. Last but not least, a quantum dot single photon source is a building block in secure communications, and therefore can be applied to quantum information processing for applications such as quantum computers. This lecture will review the recent findings and prospects on nanostructure based light emitters made with quantum-dot technology. Many applications ranging from silicon-based integrated solutions to quantum information systems will be presented. In addition, the lecture will highlight the importance of nanotechnologies on industry and society especially for shaping the future information and communication society.
Speaker Bio: Frédéric Grillot is currently a Full Professor at Télécom Paris (France) and a Research Professor at the University of New-Mexico (USA). His research interests include, but are not limited to, advanced quantum confined devices using III-V compound semiconductors, quantum dots quantum dashes, light-emitters based on intersubband transitions, non-classical light, nonlinear dynamics and optical chaos in semiconductor lasers systems as well as microwave and silicon photonics applications.
Professor Grillot has made outstanding technical contributions in photonics and optical communications. He has intensively contributed to the development of quantum dot devices enabling their utilization as future active devices with superior performance. In particular, his recent achievements on epitaxial quantum dot lasers on silicon are crucial for the development of isolation-free integrated technologies. Among his major achievements, he also reported the first private optical communication using mid-infrared chaotic light, giant pulses emission in quantum cascade devices as well as multigigabits operation in the thermal atmospheric window with unipolar quantum optoelectronics. Overall, his research is a strong input to the advancement of science and to the emerging practical applications in computer and quantum technologies, as well as in more traditional areas such as optical communications.
Professor Grillot strongly contributes to promote and support the development of the general optics community. He has served diligently and successfully Optica in particular as an Associate Editor of Optics Express, now as a Deputy Editor since September 2022. As of now, he has published more than 130 journal articles, 3 book chapters, and delivered many invited talks in major international conferences and workshops. Frédéric Grillot is also a Fellow Member of the SPIE as well as a Senior Member of Optica and the IEEE Photonics Society. In 2022, he received the IEEE Photonics Society Distinguished Lecturer Award which honors excellent speakers who have made technical, industrial or entrepreneurial contributions to the field of photonics.
Jointly organized with the IEEE Vancouver Joint Communications Chapter
Event Location:
AMPL 311
Event Time:
Monday, March 13, 2023 | 3:00 pm - 4:00 pm
Event Location:
HENN 318
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2023-03-13T15:00:00
2023-03-13T16:00:00
The Dragonfly Spectral Line Mapper: New eyes to reveal the faintest and largest structures in the universe
Event Information:
Abstract:
The majority of baryons in the universe exist outside galaxies, in the circumgalactic (CGM) and intergalactic medium (IGM). The properties of these structures are important to understand as the material they hold is required to fuel ongoing star formation in galaxies. The process of how the gas in the CGM gets into galaxies (and is blown back out through galactic feedback) is still debated, though – in fact, the total mass of the CGM of galaxies is still unknown. This mystery remains due to the near invisibility of the CGM and IGM.
In this talk, I will describe an upcoming upgrade to the Dragonfly Telephoto Array that implements ultra-narrow bandpass imaging capability on the telescope which will enable it to directly image the CGM of local galaxies. I will present the results from a pathfinder version of the upgraded Dragonfly and the plans for the full upgrade, the Dragonfly Spectral Line Mapper, which is currently under construction (with first light expected within a month!).
Bio:
Deborah uses a combination of instrumentation, observation and theoretical astrophysics to investigate galaxy formation and evolution, and the role of dark matter in the universe. She started working with and building instrumentation for the Dragonfly Telephoto Array during her PhD at the University of Toronto and the Dunlap Institute. After graduating in 2021, she has continued working with Dragonfly as a Herzberg Instrument Science Fellow at the NRC Herzberg Astronomy & Astrophysics Research Centre in Victoria, BC, Canada.
Learn More:
See Deborah's personal webpage here
See her National Research council of Canada webpage here
Event Location:
HENN 318
Event Time:
Monday, March 13, 2023 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2023-03-13T11:00:00
2023-03-13T12:00:00
Quantum devices and the frontier of many-body physics
Event Information:
Abstract:
I will make the case that new possibilities for the precise control and measurement of quantum devices have led to a quiet revolution in the way we think about physical systems, beyond the headline-grabbing promise of quantum computers. I will begin by explaining how present-day quantum devices, from systems of ultracold atoms to chains of superconducting qubits, have given a new impetus to the venerable theory of hydrodynamics, realizing regimes of non-equilibrium dynamics that were completely unanticipated even a few decades ago. I will then discuss how the age of highly controllable quantum devices calls for updated notions of “quantumness” of physical states. Traditionally, this tends to be quantified in terms of entanglement. I will argue that less well-studied notions of quantumness, such as quantum contextuality, are better suited for understanding how to prepare complicated quantum states and use them to accomplish classically difficult tasks.
Bio:
I am a theoretical physicist with broad interests in statistical physics and emergent phenomena, and a particular focus on how these concepts apply to quantum many-body systems.
At PCTS, I am exploring a cluster of interrelated questions around (i) delineating the boundary between chaos and integrability for many-body systems (ii) using quantum computational complexity as a probe for quantum dynamics (iii) classifying phases of matter by their quantum information content.
Learn More:
See Vir's Princeton webpage here
Event Location:
HENN 318
Event Time:
Thursday, March 9, 2023 | 4:00 pm - 5:00 pm
Event Location:
HENN 201
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2023-03-09T16:00:00
2023-03-09T17:00:00
Improving Student Learning: The Dual Roles of Conceptual Understanding and Reasoning Ability
Event Information:
Abstract:
Why do students make errors on physics problems? Errors that directly contradict what they have been taught? Errors that don’t arise from the failure to remember the correct formula? For the past several decades, physics education researchers have focused on one compelling explanation: students arrive in the classroom with pre-formed ideas about how the world works. Even though they may blend these ideas with those presented in formal instruction, the prior conceptions often win out. According to these accounts, students’ prior knowledge has been built through rational, if imperfect, processes of observation and analysis, and any new or different ideas presented in the classroom must likewise be built, not simply received.
Figuring out what ideas students bring with them to the classroom, and how to take them into account, has proven to be a complex, multi-faceted program of research that has significantly influenced physics teaching. However, it is not always the case that students produce incorrect answers through logical inferences based on incorrect or inappropriate premises – often they don’t know why they chose a particular answer, just that it seems right. “Dual-process” theories suggest that their answers might not be based on so-called “slow” thinking, which is deliberate and laborious. Instead they might be based on so-called “fast” thinking, which is automatic and effortless. The basic idea is that students immediately and effortlessly form a first-impression of a physics problem. If this impression is found to be satisfactory, it will be adopted. Otherwise, a deliberate and analytical process ensues. It is believed that this sequence cannot be “turned off.” That is, a first impression will always be formed. If it is attractive, and the benefits of engaging in more effortful thinking are not obvious, then a student may answer incorrectly, masking their conceptual knowledge.
In this talk, I will discuss recent efforts to improve both conceptual understanding and reasoning skills. Examples will be chosen from first-year university-level physics.
Bio:
Paula R.L. Heron is a Professor of Physics at the University of Washington. She holds a Ph.D. in physics from the University of Western Ontario. Dr. Heron’s research focuses on the development of conceptual understanding and reasoning skills. She has given numerous invited talks at international meetings and in university science departments. Dr. Heron is co-Founder and co-Chair of the biannual “Foundations and Frontiers in Physics Education Research” conference series, the premier venue for physics education researchers in North America. She has held leadership roles in the American Physical Society (APS), the American Association of Physics Teachers (AAPT), and the European Physics Education Research Group (GIREP). She served on the National Research Council committee on the status and outlook for undergraduate physics education and co-chaired an APS/AAPT joint task force that produced the report Phys21: Preparing Physics Students for 21st Century Careers. She also serves as an Associate Editor of Physical Review – PER. She is a Fellow of the APS, a co-recipient of the APS Education award with colleagues Peter Shaffer and Lillian McDermott, and recipient of the Homer Dodge Citation for Outstanding Service to the AAPT. Dr. Heron is a co-author on the upcoming 2nd Edition of Tutorials in Introductory Physics, a set of influential instructional materials.
Learn More:
See Paula's faculty webpage here
See her ResearchGate page here
Event Location:
HENN 201
Event Time:
Thursday, March 9, 2023 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2023-03-09T11:00:00
2023-03-09T12:00:00
In pursuit of entanglement: XXZ interactions for spin-squeezing in atomic and solid-state spin ensembles
Event Information:
Abstract:
Controlling many-body entanglement promises to yield both fundamental insights and practical advances. In particular, generating squeezed states for entanglement-enhanced metrology is an important near-term application of quantum systems. In past work, squeezing has been achieved in a clean, controlled setting using all-to-all Ising interactions between ultracold atoms in an optical cavity. By contrast, optically-addressable spin defects in solids, such as the nitrogen-vacancy center in diamond, are far more practical and versatile sensors, but it is not known whether the requisite ingredients for generating and detecting squeezing are attainable in this platform.
In this talk, I will discuss two complementary approaches for generating squeezed states using XXZ interactions. The first approach centers around a cavity QED platform designed to realize programmable, nonlocal spin-spin couplings. Specifically, we implement an all-to-all XXZ Hamiltonian with tunable anisotropy, strength, and sign. Images of the resulting magnetization dynamics show that XXZ interactions protect spin coherence against spatial inhomogeneities, which may enhance the robustness of future spin-squeezing protocols.
The robustness of the XXZ model against disorder opens the door to squeezing via long-range dipolar interactions within an ensemble of spin defects in diamond, for which we identify and achieve the key required ingredients: (i) a theory that elucidates if and how power-law XXZ interactions generate squeezing; (ii) a two-dimensional ensemble of strongly-interacting, optically-polarizable spins; (iii) methods for detecting squeezing despite significant technical noise.
Event Location:
HENN 318
Event Time:
Wednesday, March 8, 2023 | 4:00 pm - 5:00 pm
Event Location:
Henn 318
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2023-03-08T16:00:00
2023-03-08T17:00:00
Special Gravity Seminar: The LIGO-Virgo search for gravitational waves associated with Fast Radio Bursts Detected by CHIME/FRB
Event Information:
TALK RECORDING AVAILABLE AT: https://drive.google.com/file/d/1DJ1iAdZ5QPBlQsxkCxyLmdvBqusGGbv7/view?usp=share_link
Abstract:
I will present the results from the search for gravitational waves associated with Fast-Radio Bursts (FRBs) detected by the CHIME/FRB experiment during the LIGO-Virgo Observing Run O3a, from 1 April 2019 15:00 UTC - 1 October 2019 15:00 UTC. We have used both a generic gravitational wave transient search and a modelled search targeting coalescing binary systems. Several source types and morphologies were used during the searches. Assuming inferred FRB distances, we compare lower bounds on the GW detection distances and present upper limits on the possible energies emitted by gravitational waves for a range of transient models. I will also describe the status of the LIGO-Virgo-Kagra O3b search for gravitational wave counterparts to CHIME/FRB data. Finally, I will discuss preparations for the O4 LIGO-Virgo-Kagra Observation runs and the constraints that could be set by future joint GW/FRB searches.
Event Location:
Henn 318
Event Time:
Wednesday, March 8, 2023 | 12:00 pm - 1:00 pm
Event Location:
HENN 318
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2023-03-08T12:00:00
2023-03-08T13:00:00
Development of an EDI.I Competency Framework for Engineering Programs
Event Information:
How are concepts of equity, diversity, inclusion and Indigeneity (EDI.I) taught and assessed in applied sciences?
Why is the teaching of these concepts important for engineers and scientists and how can competency level be meaningfully assessed?
Come to listen, learn, and discuss these questions and more in this month’s EDI in PHAS Journal Club! Jessica Wolf is a 2nd year MASc student in Mechanical Engineering and will lead our discussion on her work to develop an Equity Competency Model for UBC’s Faculty of Applied Sciences. Jessica’s work is inspired by the Valley Competencies (pp. 8-16
of linked journal article) and looks to translate such frameworks into applied sciences.
Coffee and Cookies to be provided!
Event Location:
HENN 318
Event Time:
Tuesday, March 7, 2023 | 12:30 pm - 1:30 pm
Event Location:
HENN 318
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2023-03-07T12:30:00
2023-03-07T13:30:00
X-Ray Polarization Observations of Stellar Mass Black Holes in X-Ray Binaries with the IXPE and XL-Calibur Experiments
Event Information:
Abstract:
The Imaging X-Ray Polarimetry Explorer (IXPE) mission is a satellite borne observatory that measures the linear polarization of the 2-8 keV X-rays from cosmic sources. I discuss here some of the recent results obtained with IXPE for stellar mass black holes. I will furthermore give a brief description of several balloon borne X-ray and gamma ray missions on which I am working, including the hard X-ray polarimetry mission XL-Calibur, the Dilution Refrigerator and Transition Edge Sensor array test flight DR. TES, and the pointed 511 keV gamma ray mission 511-CAM.
Bio:
Professor Krawczynski works on experimental and theoretical astroparticle physics. His work aims at revealing the inner workings of astrophysical black holes, and using black hole and neutron star observations for testing the theory of General Relativity and the Standard Model of Particle Physics in regimes not accessible in terrestrial laboratories.
Learn More:
See Henric's Faculty webpage at the Washington University in St. Louis here
Event Location:
HENN 318
Event Time:
Tuesday, March 7, 2023 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2023-03-07T11:00:00
2023-03-07T12:00:00
Echos of the Early Universe in Axion Haloscopes
Event Information:
Abstract:
The coming decade will bring dramatic improvement in the axion dark-matter program as new experimental designs move beyond the proof of principle stage. In this talk I will outline two signals beyond dark matter that these instruments could discover. The first is a population of relativistic axions that were produced in the early universe and persist as a residual Cosmic axion Background (CaB). The second is high-frequency gravitational waves; I will outline how exploiting an analogy between axion and gravitational-wave electrodynamics allows for axion haloscopes to be converted into gravitational-wave telescopes.
Bio:
Nicholas Rodd grew up in Melbourne, Australia, and completed his undergraduate degrees in Science and Law at Melbourne University. He then moved to MIT, where he obtained his PhD in 2018 under the supervision of Tracy Slatyer, focusing on the indirect detection of dark matter. After MIT, Nicholas went to U.C. Berkeley as a Miller Fellow for three years, before joining the theory division at CERN in 2021, where he is currently a Staff Member.
Learn More:
View Nicholas' webpage here
See his Youtube video on the Cosmic Axion Background here
Event Location:
HENN 318
Event Time:
Monday, March 6, 2023 | 3:00 pm - 4:00 pm
Event Location:
HENN 318
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2023-03-06T15:00:00
2023-03-06T16:00:00
Baryon Cycles in the Biggest Galaxies
Event Information:
Abstract:
The universe’s biggest galaxies have both vast atmospheres and supermassive central black holes. Coupling between those two components of a large galaxy couple regulates the galaxy’s star formation rate. Models of interactions between a supermassive black hole and the large-scale atmosphere suggest that the energy released as cold gas clouds accrete onto the black hole suspends the atmosphere in a state that is marginally stable to formation of cold clouds.
A growing body of observational evidence indicates that many massive galaxies, ranging from the huge central galaxies of galaxy clusters down to our own Milky Way, are close to that marginal state. The gas supply for star formation within a galaxy in such a marginal state is closely tied to the galaxy's central potential well, as traced by the central velocity dispersion of its stars. Those findings suggest that energy released during black-hole accretion shuts down star formation when the central potential well depth exceeds a critical value determined by the galaxy’s supernova heating rate.
Bio:
I’m currently an astronomy professor at Michigan State University. My journey here started in suburban Philadelphia. I graduated from Cheltenham High School in 1979 and from Princeton in 1983, with an A.B. in Astrophysical Sciences. My Ph.D. in Astrophysics (1990) is from the University of Colorado. Then came three years as a Research Fellow at Caltech, two more as a Hubble Fellow at Johns Hopkins, and eight as an astronomer at the Space Telescope Science Institute, working on the Hubble Space Telescope project, before Michigan State brought me on board in 2003.
Learn more:
View Dr. Voit's personal website here.
View Dr. Voit's Michigan State faculty webpage here.
Event Location:
HENN 318
Event Time:
Monday, March 6, 2023 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2023-03-06T11:00:00
2023-03-06T12:00:00
Probing fundamental physics by mapping the millimeter and submillimeter sky
Event Information:
Abstract:
Cosmology has transformed from a field of speculation to precision science as a result of a wealth of data from sensitive instruments. In particular, precise observations of the cosmic microwave background (CMB) have revolutionized our understanding of the Universe. Despite the success of the standard model of cosmology (ΛCDM) in describing much of the cosmos with just six parameters, many fundamental questions remain unresolved. Are there primordial gravitational waves? Are there new light relic particles? How will the current cosmological tensions be resolved? Improved mapping of the millimeter and submillimeter sky will help address these questions. I will highlight recent results from the Atacama Cosmology Telescope (ACT), and describe how the new ACT maps will advance our understanding of the Universe beyond Planck. I will also present recent progress on CCAT-prime and Simons Observatory that are paving the way for CMB-S4 in pursuit of next generation cosmology.
Bio:
I am an NSF Astronomy and Astrophysics Postdoctoral Fellow at Cornell University. My primary research interest is on understanding the formation and evolution of our universe through building sensitive instruments to make precise measurements and applying modern data analysis techniques to them.
On the experimental side I am developing novel instruments using MKID arrays for the CCAT-prime project. MKIDs are a promising detector technology for making future sub-mm measurements, but they have yet to be demonstrated from the best observing sites in the world such as that to be used by CCAT-prime. As a graduate student at Princeton University I worked on a different detector technology, TES arrays, for the Atacama Cosmology Telescope. In addition, I investigated infrared blocking filters, a crucial component in mm and sub-mm telescope receivers.
I continue to analyze data from the Atacama Cosmology Telescope. Recently, the cosmological data analysis I led resulted in a new precise measurement of the age and expansion rate of our universe (covered on Gizmodo!). I’ve also worked on searching for B-modes and characterizing foreground emission for measuring B-modes. This led to a definitive measurement of the correlation of the polarized thermal dust and synchrotron radiation from the Milky Way.
Learn More:
View Steve's faculty webpage from Cornell University here
See his homepage here
Event Location:
HENN 318
Event Time:
Monday, March 6, 2023 | 10:00 am - 11:00 am
Event Location:
HENN 309
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2023-03-06T10:00:00
2023-03-06T11:00:00
X-ray Insights into the Connection between Quenching of Star Formation and Galaxy Stellar Velocity Dispersion
Event Information:
Abstract:
There is a surprisingly tight correlation between galaxies with quenched star formation and their central velocity dispersion, which also correlated with the central black hole's mass. Those correlations suggest that the central black hole is the culprit. However, radio and X-ray observations of these galaxies show that the black hole's considerable energy production can bypass the galaxy and thermalize at distances tens of kiloparsecs from the galaxies' stars. The circumgalactic medium (CGM) may therefore be what connects black hole feedback with quenching of star formation. The CGM can be difficult to observe, but X-ray observations have yielded important clues about the how black holes and the CGM are connected.
We have proposed a "valve" model for that connection, whereby the black hole lifts the CGM, lowering the circumgalactic pressure and allowing two distinct states for the galaxy: a wind-dominated mode where winds from type 1a supernovae suppress gas cooling, and a precipitation-dominated mode where cool gas can rain from the hot CGM. This cold "multi-phase" gas can feed the black hole and trace amounts of star formation, completing and sustaining the feedback cycle that keeps a galaxy quenching. The central velocity dispersion - the observational signature of the central gravitational potential - may determine which state prevails in each galaxy.
We will discuss what the X-ray observations have shown so far, and what future X-ray and UV observations may unlock.
Bio:
Megan Donahue studies clusters of galaxies. Cluster evolution tells us about the matter density of the universe, because the formation of galaxy clusters is governed by gravitational physics. She pays particular attention to how clusters are found, because any bias in finding clusters can lead to a bias in our conclusions about them. She also studies the metallicity, distribution, and physics of intergalactic gas. Is this really where most of the baryons are hiding? Her work includes models and observational tests of cooling flows in the gas within clusters. Strange things are afoot in cluster cores and she would like to sort it out.
Professor Donahue was named a Fellow of the American Physical Society in October 2016 for "advanced cosmological observations and analyses of galaxy clusters, and of the relationship between the thermodynamic state of circumgalactic gas around massive galaxies, the triggering of active galactic nucleus feedback, and the regulation of star formation in galaxies" after nomination by the APS Division of Astrophysics.
Professor Donahue was elected as President of the American Astronomical Society (AAS) in 2017.
Learn More:
View Dr. Donahue's faculty webpage here
View her Home page here
Event Location:
HENN 309
Event Time:
Thursday, March 2, 2023 | 4:00 pm - 5:15 pm
Event Location:
HENN 201
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2023-03-02T16:00:00
2023-03-02T17:15:00
3 Minute Thesis Competition, Physics and Astronomy Heat
Event Information:
Three Minute Thesis (3MT)
*On Thursday March 2, 2023 from 4:00 - 5:15pm during the Department Colloquium, in HENN 201*
The Three Minute Thesis (3MT) is an academic competition that assists current graduate students with fostering effective presentation and communication skills. Participants have just three minutes to explain the breadth and significance of their research project to a non-specialist audience. Over 200 universities participate in this fun, highly informative and very entertaining event. UBC was one of the first Universities in North America to host a 3MT competition.
Read more about the PHAS Heat of 3MT.
Register for the 2023 UBC Physics and Astronomy Heat of 3MT.
For full information, schedule, rules, eligibility, coaching sessions, judging criteria etc, see UBC 3 Minute Thesis.
Please note that two of our recent PHAS finalists who placed in the top 3 (and won cash prizes!) in the past 4 years took advantage of the 3MT Personal Presentation Feedback Sessions (20 min by appointment). Register for Feedback Session.
Event Location:
HENN 201
Event Time:
Thursday, March 2, 2023 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2023-03-02T11:00:00
2023-03-02T12:00:00
New directions for the detection of light dark matter
Event Information:
Abstract:
Dark matter remains one of the central mysteries of cosmology and particle physics. Here, I introduce a new set of strategies in the search for the universe's missing mass. I will present a series of recent theoretical developments that predict that molecules and nano-materials are optimal targets to use in next-gen detectors looking for dark matter beyond the weak scale. I will show that molecular detectors can be sensitive to the direction of the dark matter wind, producing daily-modulating signals. Additionally I will show that semiconducting nano-crystals (quantum dots) can produce inherently low-noise signals following dark-matter induced excitations. Finally, I will advocate for the further development of the theoretical formalism underlying these novel strategies and comment on emerging collaborations that aim to rapidly develop and deploy these promising detectors.
Bio:
Carlos Blanco completed his PhD at the Kavli Institute for Cosmological Physics at the University of Chicago, and is currently working at Princeton University as a postdoctoral Research Associate.
Learn More:
View Carlos' web profile here
See past publications via INSPIRE website here
See a YouTube video of Carlos speaking on "New Directions in Dark Matter Direct Detection" from March 02, 2022
Event Location:
HENN 318
Event Time:
Thursday, March 2, 2023 | 10:00 am - 11:00 am
Event Location:
AMPL 311
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2023-03-02T10:00:00
2023-03-02T11:00:00
The Quantum Twisting Microscope
Event Information:
Abstract: In this talk, I will present a new type of scanning probe microscope, the Quantum Twisting Microscope (QTM), capable of performing local quantum interference measurements at a twistable interface between two quantum materials. Its working principle is based on a unique tip made of an atomically-thin two-dimensional material. This tip allows electrons to coherently tunnel into a sample at many locations at once, with quantum interference between these tunneling events, making it a scanning electronic interferometer. With an extra twist degree of freedom, our microscope becomes a momentum-resolving local probe, providing powerful new ways to study the energy dispersions of interacting electrons. I will present various experiments performed with this microscope, demonstrating quantum interference at room temperature, probing the conductance of in-situ twisting interfaces, and imaging local energy dispersions of graphene and twisted bilayer graphene.
Speaker Bio: I am a postdoctoral researcher working at the Weizmann Institute of Science with Prof. Shahal Ilani. I completed my Ph.D. with Prof. Andre Geim and Prof. Irina Grigorieva at the University of Manchester, UK. My research focuses on using unique scanning probe microscopes to visualize the electronic properties of 2D materials and vdW heterostructures.
Event Location:
AMPL 311
Event Time:
Wednesday, March 1, 2023 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2023-03-01T11:00:00
2023-03-01T12:00:00
How do the most luminous black holes accrete and expel gas?
Event Information:
Abstract:
The gravitational pull of a black hole attracts gas and forms a physical laboratory whose extreme conditions cannot be replicated on Earth. The infalling gas forms an accretion disk where the interplay between hydromagnetic processes and the warping of space-time releases gravitational energy in the form of radiation, relativistic jets, and winds. It is likely that most gas falls into supermassive black holes when the accretion rate approaches the Eddington limit (L=Ledd), at which point radiation pressure overcomes gravity. To date, our knowledge of such `luminous’ black hole accretion disks mostly relies on semi-analytical models, supplemented by a very limited set of numerical simulations.
In my talk I will discuss new insights gained from the first radiative general relativistic magnetohydrodynamics (GRMHD) simulations of luminous accretion disks. I will demonstrate that magnetic fields lead to the formation of a hot corona and that misalignment between the disk and black hole spin axis can explain quasi-periodic oscillations, which have remained a mystery for over 30 years.
I will finish my talk by discussing the opportunities the next-generation of GRMHD simulations will bring in addressing the origin of non-thermal radiation, cosmic rays, and neutrinos from accreting black holes.
Bio:
Matthew Liska is a computational astrophysicist with an interdisciplinary interest in astrophysics, plasma physics and computation. He is the main developer of the world's first GPU accelerated GRMHD code ("H-AMR") which he uses to study accretion onto compact objects such as black holes. He completed his PhD in 2019 at the University of Amsterdam and is now a John Harvard & ITC Fellow at Harvard CFA.
Learn More:
See Matthew's webpage here
Event Location:
HENN 318