Events List for the Academic Year
Event Time:
Monday, December 2, 2019 | 3:00 pm - 4:00 pm
Event Location:
Hennings 318
Add to Calendar
2019-12-02T15:00:00
2019-12-02T16:00:00
Quenching star formation in massive galaxies
Event Information:
A fundamental question in galaxy evolution is how galaxies acquire diverse colours and morphologies. The current paradigm suggests that massive galaxies experienced accelerated growth in the early Universe and eventually quenched their star formation. Exactly how galaxies quench is not well-understood. Many mechanisms have been proposed in the literature, yet a definite conclusion remains elusive. I will present an overview of the current state of the art and discuss future perspectives on solving this decade-old puzzle.
Event Location:
Hennings 318
Event Time:
Thursday, November 28, 2019 | 5:00 pm - 6:00 pm
Event Location:
Hebb Theatre
Add to Calendar
2019-11-28T17:00:00
2019-11-28T18:00:00
Investigation of Multi-frequency Raman Generated Spectra
Event Information:
Since the advent of lasers, many different nonlinear optical techniques have led to shorter, higher-intensity pulses. At Waterloo, we are studying Multi-frequency Raman generation (MRG), which efficiently generates a large number of Raman orders spanning the spectral region from the infrared to the ultraviolet. The bandwidth of the Raman orders is sufficient to generate single-femtosecond duration pulses. While the pulse duration is longer than what is possible with high order harmonic generation, the conversion efficiency is much higher. While most research in this field is concerned with making as many Raman orders as possible, we noticed that the spectra of the individual Raman orders changed dramatically when changing either the dispersion in the nonlinear medium or the laser pump intensity. In this talk, I will discuss the possible physical process causing these changes in the spectra as well as how the changes effect the generation of ultrashort intense pulses.
Event Location:
Hebb Theatre
Event Time:
Thursday, November 28, 2019 | 2:00 pm - 3:00 pm
Event Location:
Brimacombe 311
Add to Calendar
2019-11-28T14:00:00
2019-11-28T15:00:00
CM Seminar - Modelling muons in magnetic materials
Event Information:
Abstract:Muon spin spectroscopy (µSR), a technique in which spin-polarised positive muons are implanted into a material, has been successfully used to study a wide range of materials. Interpreting µSR spectra, however, often requires knowledge of the precise muon stopping site(s) in the material. In this talk, I will outline our approach to finding muon stopping sites using density functional theory (DFT). We have recently applied this approach to the prototypical linear magnetoelectric, Cr₂O₃. We find that the positively charged muon occupies several distinct interstitial sites, and displays a rich dynamic behaviour involving local hopping, thermally activated site transitions and the formation of a charge-neutral complex composed of a muon and an electron polaron. Using this work as a case study, I will highlight several challenges to modelling muons in magnetic materials and offer some approaches to overcoming these challenges.
Bio:
J. Kane Shenton is a postdoctoral researcher in the group of Nicola A. Spaldin at ETH Zurich where he works on the theory and simulation of magnetic and multiferroic materials. Kane has worked closely with the Kiefl group at UBC/TRIUMF/SB-QMI on developing methods to model muons in materials. These methods can aid in the interpretation of µSR spectra and expand our understanding of the doping characteristics of hydrogen defects in magnetic materials. Kane obtained his PhD, on understanding structure-function relationships in bismuth ferrite, from University College London (UCL) in 2018, under the supervision of David R. Bowler and Wei Li Cheah.
Event Location:
Brimacombe 311
Event Time:
Wednesday, November 27, 2019 | 2:00 pm - 3:00 pm
Event Location:
Brimacombe 311
Add to Calendar
2019-11-27T14:00:00
2019-11-27T15:00:00
CM Seminar - Topological Skyrmion phases of matter
Event Information:
Abstract
We introduce topological phases of matter defined by non-trivial homotopy groups into the literature, the chiral and helical topological Skyrmion insulators. These phases generalize and extend the concepts of the Chern insulator and quantum spin Hall insulator, respectively.
Hamiltonians characterizing chiral and helical topological Skyrmion insulator phases, which also possess particle-hole symmetry, may be re-interpreted as Bogoliubov de Gennes Hamiltonians describing counterpart chiral and helical topological Skyrmion superconductor phases of matter, and we find that both superconducting phases are realized in tight-binding models for spin-triplet superconductivity in transition metal oxide compounds, with symmetry requirements for realizing these phases widespread. The chiral topological Skyrmion superconductor phase is furthermore realized for a parameter set characterizing Sr2RuO4 with spin-triplet superconductivity. As well, one kind of topological phase transition by which the relevant topological invariant, the Skyrmion number, can change occurs without the closing of energy gaps in a system described by a quadratic Hamiltonian, which has important consequences very broadly for study of topological phases of matter.
Event Location:
Brimacombe 311
Event Time:
Wednesday, November 27, 2019 | 11:00 am - 12:00 pm
Event Location:
TRIUMF Auditorium
Add to Calendar
2019-11-27T11:00:00
2019-11-27T12:00:00
Shape Coexistence in Nuclei
Event Information:
Shape coexistence in nuclei occurs because the quadrupole-quadrupole correlations are extremely strong therein. At the neutron rich side, they can even make some semi-magic nuclei deformed in their ground states, leading to the so called Islands of Inversion. I will visit these islands and describe them with the Spherical Shell Model with (large scale) Configuration Mixing, guided by the SU(3) heuristics. The tour will finish in doubly magic 78Ni and the fifth Island of Inversion. An intriguing point is whether the shape parameters in the intrinsic frame, beta and gamma, survive in the laboratory frame. Using the Kumar invariants up to sixth order, we have computed exactly the variances of beta and gamma. They tell us that beta can be rather soft and gamma meaningless. In addition, it turns out that whereas the notion of deformed nucleus still makes sense in many cases, the notion of spherical nucleus never does.
Event Location:
TRIUMF Auditorium
Event Time:
Monday, November 25, 2019 | 3:00 pm - 4:00 pm
Event Location:
Hennings 318
Add to Calendar
2019-11-25T15:00:00
2019-11-25T16:00:00
Unveiling the stellar halo distribution with multi-wavelength photometry
Event Information:
The stellar halo of our Galaxy is mostly formed by stars that were initially residing in dwarf galaxies and globular clusters, which have been disrupted by the tidal field of the Milky Way. Because the structures created by these disruptions can survive for a long time, the stellar halo is the best place to probe the accretion history of our Galaxy.
I will present recent work that in particular makes use of the new deep u-band component of the Canada-France-Imaging Survey (CFIS), in combination with other surveys, such as Pan-STARRS 1 and Gaia. With these observations, it have been possible to study the stellar halo using different type of stars, such as the Blue Horizontal Branch stars (BHBs) or White Dwarfs (WDs). We have recently developed a machine-learning-based algorithm that disentangles the giants from the dwarfs, and that derives their distances and metallicities with high precision, using only the available photometry. This new dataset will be extremely valuable for future studies of the stellar halo of the Milky Way, using different stellar populations, in order to reconstruct the formation history of our Galaxy and probe the dark-matter distribution that surrounds it.
Event Location:
Hennings 318
Event Time:
Thursday, November 21, 2019 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
Add to Calendar
2019-11-21T16:00:00
2019-11-21T17:00:00
Quantum annealing with the D-Wave processor
Event Information:
As current transistor-based computational technologies reach their fundamental limitations, quantum computing offers a new paradigm that could radically increase our capacity for solving difficult problems. This talk will present an overview of quantum annealing as a specific method of quantum computation and discuss D-Wave's implementation based on superconducting flux qubits. I'll present some recent work done using our processor, including materials simulations of topological phase transitions in frustrated magnetic systems. This work represents the first experimental demonstration of the Kosterlitz-Thouless phase transition (winner of the 2016 Nobel prize in physics) in a transverse-field Ising model, and brings to mind Richard Feynman's original vision for quantum computing.
Event Location:
Hennings 201
Event Time:
Thursday, November 21, 2019 | 2:00 pm - 3:00 pm
Event Location:
Brimacombe 311
Add to Calendar
2019-11-21T14:00:00
2019-11-21T15:00:00
CM Seminar - Obstacles to variational quantum simulation and optimization
Event Information:
Abstract
Variational quantum algorithms such as VQE or QAOA aim at simulating low-energy properties of quantum many-body systems or finding approximate solutions of combinatorial optimization problems.
Such algorithms, designed for near-term quantum processors, employ variational states based on low-depth quantum circuits to minimize the expected energy of a Hamiltonian describing the system of interest.
Given the current enthusiasm for variational quantum algorithms, it is natural to question whether or not they can be more powerful than classical algorithms in some sense.
In this talk I will explain how general structural properties of variational states such as locality and symmetry may be used to assess their computational power.
In particular, I will show that variational quantum algorithms based on constant depth circuits with nearest-neighbor gates on a 2D grid of qubits can be simulated classically in linear time.
Furthermore, quantum approximate optimization algorithms based on low-depth circuits fail to achieve advantage over the best known classical optimization algorithm for certain instances of the MAX-CUT problem.
Based on
arXiv:1909.11485
arXiv:1910.08980
Biography
I am a Research Staff Member at the IBM T.J. Watson Research Center.
My research interests focus mainly on quantum algorithms, quantum error correction, and computational complexity theory.
Prior to joining IBM, I spent several years as a postdoc at California Institute of Technology in John Preskill's group.
I obtained my PhD at Landau Institute for Theoretical Physics in 2003.
Event Location:
Brimacombe 311
Event Time:
Tuesday, November 19, 2019 | 11:00 am - 12:00 pm
Event Location:
TRIUMF Auditorium
Add to Calendar
2019-11-19T11:00:00
2019-11-19T12:00:00
Radiochemical Aspects of Proton Accelerator Radioisotope Production
Event Information:
A variety of radioisotopes with different nuclear properties can be generated via proton beam activation of suitable target materials. Such radioisotopes play an important role in nuclear medicine, nuclear forensics and environmental research. Experimental planning involves nuclear reaction evaluation, target material selection, particle energy adjustment and the design of hot cell tailored chemical recovery and purification procedures. Three recent isotope development projects, radioarsenic, radiorhenium bulk manufacturing and the production of therapy alpha emitters along with associated activation and fission products, are introduced to serve as instructive examples for the illustration of the radiochemical facets associated with radionuclide formation, recovery and purification.
Event Location:
TRIUMF Auditorium
Event Time:
Monday, November 18, 2019 | 3:00 pm - 4:00 pm
Event Location:
Henning 318
Add to Calendar
2019-11-18T15:00:00
2019-11-18T16:00:00
Deciphering the baryonic universe: from Cosmic Dawn till today
Event Information:
The history of baryonic structures, particularly after the epoch of "Cosmic Dawn'"- the onset of the earliest stars and galaxies - is widely considered the 'final frontier' of observational cosmology today. Over the last decade, considerable effort has gone into investigating the nature of baryonic matter, theoretically and observationally. I will overview my current research related to atomic hydrogen and its evolution over 12 billion years of cosmic time, which involves a novel data driven framework developed for interpreting current and future observations. Extensions of this model pave the way towards a comprehensive understanding of molecular gas evolution, allowing us to interpret results from ongoing surveys. I will introduce a new approach capable of unmasking the hitherto elusive nature of Damped Lyman Alpha (DLA) systems, the largest high-redshift reservoirs of atomic hydrogen. These studies open up the exciting possibility of constraining fundamental physics from the Cosmic Dawn.
Event Location:
Henning 318
Event Time:
Thursday, November 14, 2019 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
Add to Calendar
2019-11-14T16:00:00
2019-11-14T17:00:00
Simulating the Universe with Machine Learning
Event Information:
The ever-increase need for accurate prediction for complex non-linear processes leads to large scale dynamical systems whose simulations and analysis make overwhelming and unmanageable demands on computational resources. The evolution of the Universe is one of these complex processes that the computational cost of the traditional full-order numerical simulations is extremely prohibitive.
In this talk, we will talk about our attempts and sometimes successes in modeling the Universe's complex processes with machine learning instead of numerically solving the correct set of equations. We use state of the art deep learning methods to "learn" to "simulate" the interactions of planetary systems, the gravitational interaction of the entire Universe (with dark matter and dark energy) and the hydrodynamical interactions among the gas particles in the Universe. We will also report and discuss a couple interesting cases in which our model generalizes far beyond our training set, and the implications therein. Are machines able to extrapolate far beyond what they are shown, just like humans who can figure out the physical laws that predict phenomena that are not yet observed?
Event Location:
Hennings 201
Event Time:
Thursday, November 14, 2019 | 2:00 pm - 3:00 pm
Event Location:
Hennings 318
Add to Calendar
2019-11-14T14:00:00
2019-11-14T15:00:00
CM Seminar - Direct Imaging of Orbitals in Quantum Materials
Event Information:
The search for new quantum materials with novel properties is often focused on materials containing transition-metal, rare-earth and/or actinide elements. The presence of the atomic-like d or f orbitals provides a fruitful playground to generate novel phenomena. The intricate interplay of band formation with the local electron correlation and atomic multiplet effects leads to phases that are nearly iso-energetic, making materials’ properties highly tunable by doping, temperature, pressure or magnetic field. Understanding the behavior of the d and f electrons is essential for designing and controlling novel quantum materials. Therefore, identifying the d or f orbitals that actively participate in the formation of the ground state is crucial. So far, these orbitals have mostly been deduced from optical, X-ray and neutron spectroscopies in which spectra must be analyzed using theory or modelling. This, however, is also a challenge in and of itself, since ab-initio calculations hit their limits due to the many-body nature of the problem.
Here we developed a new experimental method that circumvents the need for involved analysis and instead provides the information as measured. With this technique, we can make a direct image of the active orbital and determine what the atomic-like object looks like in a real solid. The method, s-core-level non-resonant inelastic X-ray scattering (s-NIXS), relies on high momentum transfer in the inelastic scattering process, which is necessary for dipole-forbidden terms to gain spectral weight. To demonstrate the strength of the technique, we imaged the text-book example, x2-y2/3x2-r2 hole orbital of the Ni2+ ion in NiO single crystal (see Figure 1). We will present the basic principles of s-NIXS and its experimental implementation. We will also show how we can apply this technique to unveil the active orbitals in complex oxides as well as to determine the orbital character in highly metallic systems such as elemental Cr, Fe, and Ni.
Figure 1: High momentum transfer vector allows the dipole-forbidden 3sà3d transition to gain spectral weight. Directional dependence of the spectral intensity associated with the 3sà3d transition directly maps the local hole charge distribution.
[1] H. Yavaş, M. Sundermann, K. Chen, A. Amorese, A. Severing, H. Gretarsson, M.W. Haverkort,
L.H. Tjeng, Nature Physics (2019) ; https://doi.org/10.1038/s41567-019-0471-2.
Event Location:
Hennings 318
Event Time:
Wednesday, November 13, 2019 | 7:30 pm - 9:00 pm
Event Location:
Chem B250
2036 Main Mall, UBC Vancouver
2036 Main Mall, UBC Vancouver
Add to Calendar
2019-11-13T19:30:00
2019-11-13T21:00:00
Quantum Annealing and Computation
Event Information:
Why climb mountains when you can tunnel through them? Harnessing quantum tunneling holds great promise to speed up solutions to optimization problems, ranging from design of circuit boards to protein folding. When computers optimize, they are doing the analog of the physical process of annealing. I will discuss experiments on disordered magnets that quantitatively compare quantum and classical annealing, and demonstrate quantum speedup for reasons that can be understood at a microscopic level. This type of computation follows from Richard Feynman's concept of a quantum computer, and underlies the power of D-Wave machines. Finally, I will discuss the possibility of programmability for spins in disordered magnetic systems, showing recent results from our Lab on quantum spin liquids.
Event Location:
Chem B250
2036 Main Mall, UBC Vancouver
Event Time:
Thursday, November 7, 2019 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
Add to Calendar
2019-11-07T16:00:00
2019-11-07T17:00:00
Nanogold and its surprising new properties
Event Information:
A variety of new properties emerges in nanostructured metallic materials. These new properties are consequence of the collective excitation of conducting electrons, known as surface-plasmon resonances (SPR). For instance, the color of noble metals, such as gold and silver, can be controlled at the nanoscale by tuning the geometric characteristics of the nanostructures. Surface plasmon (SP) waves can propagate at the surface of thin metal films and this property can be explored for 2D imaging applications. Another very interesting consequence of SPR is the phenomenon of electric field localization. Once the SPR condition is established, metallic nanostructures can act as tiny antennas that capture visible radiation and concentrate it in sub-wavelength regions. Molecules exposed to the localized fields can experience a large increase in their spectroscopic response. This leads to unique spectroscopic phenomena, such as the surface-enhanced Raman scattering (SERS) effect. The optical fields achieved in certain metallic nanostructures can be very strong and only accessible to a very small number of molecules (since they are also confined to very small regions). Ultimately, in certain conditions, SERS allows the detection of single adsorbed species. In this work, we will discuss our efforts in imaging propagating waves on metal films. We will also explore the use of localized SPs from individual metallic nanoparticles for single molecule localization and spectroscopy.
Event Location:
Hennings 201
Event Time:
Thursday, November 7, 2019 | 2:00 pm - 3:00 pm
Event Location:
Brimacombe 311
Add to Calendar
2019-11-07T14:00:00
2019-11-07T15:00:00
CM Seminar - Unconventional magnetism and quantum disorder in NaYbO2
Event Information:
Abstract: The triangular lattice of antiferromagetically coupled spins has long served as the paradigm of geometric magnetic frustration. An accompanying host of unconventional magnetic ground states predicted in this setting, and, as the spins on the lattice approach the quantum limit, these range from predictions of quantum spin liquid phases to unusual regimes of fluctuation-driven order. While ideal manifestations of materials with perfect equilateral triangles of S=1/2 ions are rare, the field has recently enjoyed a resurgence due to the development of new classes of materials possessing nearly ideal triangular lattices decorated instead with rare-earth ions. At sufficiently low temperatures for Kramers ions such as Yb, it then becomes possible to explore the magnetism of an ideal Jeff=1/2 triangular lattice of moments. Here I will present some of our recent work exploring the magnetic ground state of one such compound, NaYbO2, which forms a model triangular lattice of frustrated Yb3+ ions within a chemically ideal framework. Despite evidence for substantial magnetic exchange for a Yb-based compound, no signatures of magnetic order are detected down to 50 mK. Instead a quantum disordered state manifests which can be driven via the application of a magnetic field into a fluctuation-driven “up-up-down” plateau phase prior to reaching the fully field-polarized state. The implications of our findings regarding the formation of intrinsic quantum disorder in NaYbO2 will be discussed.
Biography: Prof. Stephen Wilson serves as an Associate Professor and the Associate Chair of the Materials Department at the University of California, Santa Barbara. After obtaining his Ph.D. from the Physics Department at University of Tennessee in 2007, he worked at Lawrence Berkeley National Laboratory as a postdoc prior to joining the faculty of the Physics Department at Boston College in 2010 as an Assistant Professor. After moving to UC Santa Barbara in 2014, he has since been appointed an Associate Director of the California Nanosystems Institute and also serves as a co-director of the recently established NSF Quantum Foundry on campus. His research group focuses on the exploration of novel electronic states and phase behaviors in a variety of materials ranging from quantum magnets to strongly spin-orbit coupled correlated electron systems.
Event Location:
Brimacombe 311
Event Time:
Thursday, November 7, 2019 | 9:00 am - 11:00 am
Event Location:
Room 203, Graduate Student Centre (6371 Crescent Road)
Add to Calendar
2019-11-07T09:00:00
2019-11-07T11:00:00
Final PhD Oral Examination (Thesis Title: “Nuclear Structure Corrections in Muonic Atoms with Statistical Uncertainty Quantification”)
Event Information:
Abstract:
The discovery of the proton and deuteron radius puzzles from Lamb shift measurements of muonic atoms has initiated experimental efforts to probe heavier muonic systems and casts doubt on earlier analysis based on ordinary atoms. For muonic atoms, the large muon mass results in a Bohr radius about 200 times smaller with respect to their electronic counterparts, making them sensitive to nuclear structure effects. These effects dominate the uncertainty budget of the experimental analysis and diminish the attainable accuracy of charge radii determinations from Lamb shift spectroscopy. This dissertation investigates the precision of nuclear structure corrections relevant to the Lamb and hyperfine splitting in muonic deuterium to support ongoing experiments and shed light on the puzzles. Using state-of-the-art nuclear models, multivariate regression analysis and Bayesian techniques, we estimate the contribution of all relevant uncertainties for nuclear structure corrections in muonic deuterium and demonstrate that nuclear theory errors are well constrained and do not account for the deuteron radius puzzle. This uncertainty analysis was carried out using the “η-expansion” method that has also been applied to A ≥ 2 nuclei. This method relies on the expansion of a dimensionless parameter η, with η < 1, up to second order. To estimate the truncation uncertainty of this method and to improve future calculations of nuclear structure effects in other nuclei, we introduce an improved formalism based on a multipole expansion of the longitudinal and transverse response functions that contains higher order terms in η, and generalize the method to account for the cancellation of elastic terms such as the Friar moment (or third Zemach moment). This method is then adapted to address the nuclear structure corrections to the hyperfine splitting. iii The hyperfine splitting is dominated by magnetic dipole transitions that are sensitive to the effects of two-body currents. Therefore, we develop the formalism of the next-to-leading-order two-body magnetic moment contributions to the magnetic dipole. These operators are applied to A = 2,3 and A = 6 systems in anticipation of the upcoming experiments in µ 6,7Li2+ ions. We find that two-body contributions are important to reach agreement with experiment
Event Location:
Room 203, Graduate Student Centre (6371 Crescent Road)
Event Time:
Wednesday, November 6, 2019 | 2:00 pm - 3:00 pm
Event Location:
TRIUMF Auditorium
Add to Calendar
2019-11-06T14:00:00
2019-11-06T15:00:00
Higgs Boson decay as a probe to the unsolved mysteries in the Universe: dark energy, dark matter and missing antimatter
Event Information:
Despite being a remarkably simple theoretical model, the Higgs mechanism is the only known theory that is connected to some of the most profound mysteries in the modern physics: dark energy, dark matter and missing antimatter. Measurements of the Higgs boson decay may shield lights on those open questions. In this talk, I will present a few selective results from the ATLAS experiment on the Higgs boson decays. Namely the first observation of the Higgs boson decay to a pair of b-quarks, which had eluded us for many years despite it is the most probable Higgs decay channel; novel techniques to search for potential new physics using the hardonically decaying Higgs boson, and a first search for singly produced long-lived neutral particle that may be realized via Higgs portal. The talk will mainly focus on general descriptions of the measurements without too much technical details, so that the content is accessible to non experimental particle physicists.
Event Location:
TRIUMF Auditorium
Event Time:
Tuesday, November 5, 2019 | 12:00 pm - 2:00 pm
Event Location:
Hennings 318
Add to Calendar
2019-11-05T12:00:00
2019-11-05T14:00:00
PHAS equity and inclusion open house
Event Information:
What is the Equity and Inclusion in PHAS group? Come to our open house to learn about our mission, what we are doing to help promote opportunities for our community, how to get involved, and learn about equity issues. We are offering a lunch and poster session to mingle with everyone in our department to engage in the conversation around equity, inclusion and diversity.
In the afternoon we invite you to attend the workshop to learn about positive space given by the UBC E&I office.
Come and go as you please throughout the event! We can’t wait to see you there!
Time
Event
Location
12:00 – 1:00 pm
Lunch and poster session
Hennings 318
1:00 – 2:00 pm
Positive Space by Dr. Rachael E. Sullivan
UBC Equity and Inclusion Office
Hennings 318
Workshop:
Positive Space by UBC E&I
Is your UBC working, learning or living environment welcoming and inclusive to sexual and gender diverse students, staff and faculty? Would you like to learn more how to improve and positively impact the climate for sexual and gender diversity?
The Positive Space foundational workshop covers current language, issues, resources, and best practices in an interactive and experiential learning environment. Participants will gain relevant knowledge and skills to use in their academic, work and campus life.
This event is sponsored by:
Event Location:
Hennings 318
Event Time:
Monday, November 4, 2019 | 3:00 pm - 4:00 pm
Event Location:
Hennings 318
Add to Calendar
2019-11-04T15:00:00
2019-11-04T16:00:00
Stellar Streams from Globular Clusters in the Local Universe
Event Information:
Stellar streams form when a gravitationally bound ensemble of stars tidally tears apart, due to an underlying galactic potential. From the vast population of stellar streams in the Milky Way, we know that the morphology of thin, stellar streams, in particular, can be used to test the distribution and nature of dark matter. It is therefore crucial to extend searches for these streams to other galaxies than the Milky Way. In the course of the next decade, a wealth of extragalactic stellar stream observations will become available, and stellar streams will be observed in galaxies out to several hundred Mpc. How will we take full advantage of these observations and decipher the astrophysical information the data contain? In this talk, I review the current and future prospects of detecting stellar streams in external galaxies with a focus on globular cluster streams. I create mock stellar streams and inject them into data from the PAndAS M31 survey to produce simulated M31 backgrounds, mimicking what WFIRST will observe in M31. Additionally, I estimate the distance limit to which globular cluster streams will be observable. Recent results demonstrate that for a 1 hour exposure, using conservative estimates, WFIRST should detect globular cluster streams in resolved stars in galaxies out to distances beyond 3.5 Mpc. This volume contains at least 199 galaxies of which > 90% are dwarfs. If these external galaxies do not host spiral arms or galactic bars, gaps in their stellar streams provide an ideal test case for evidence of interactions with dark matter subhalos. Furthermore, obtaining a large sample of thin stellar streams can help constrain the orbital structure and hence the potentials of external halos.
Event Location:
Hennings 318
Event Time:
Thursday, October 31, 2019 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
Add to Calendar
2019-10-31T16:00:00
2019-10-31T17:00:00
The Charge Distribution on a Conductor
Event Information:
In electrostatics any excess charge on a conductor goes to the surface. This is due, of course, to the mutual repulsion of like charges. But it depends critically on the precise form of Coulomb's law and on the dimensionality of the conductor. I will discuss some intriguing examples, including the vexed case of a conducting needle.
This week, Equity and Inclusion in PHAS has organized a meet-and-greet with David Griffiths after his talk. Please join us in Hennings 318 from 5:15-7:00pm for drinks, snacks, and even the chance to get Dr. Griffiths to sign your well-used textbook!"
Event Location:
Hennings 201