## WITP Summer Student Symposium 2022

17 Aug 2021, UWinnipeg & Online

#### Abstracts

**Isabel Sander**

*Pulsar Wind Nebulae: Powerful Cosmic Ray Accelerators*

When a massive star explodes in a supernova, it often leaves behind a
rapidly spinning compact neutron star. Young, energetic neutron stars
generate strong relativistic winds, which as they interact with the
surrounding medium, create a pulsar wind nebula (PWN) that can shine
across the electromagnetic spectrum. PWNe make the largest population
of gamma-ray sources in our galaxy and are strong candidates for
acceleration of cosmic rays to PeV energies (pevatrons). In
collaboration with Columbia University researchers, we are analyzing
PWNe in multiple wavelengths to form a more complete understanding of
these extreme sources. In this presentation, we highlight our research
targeting the PWN G309.92-2.51 making use of NASA's NuSTAR satellite
sensitive to the high-energy x-ray band.

**Arka Chatterjee**,
Slides

*Estimation of Spin of the Galactic Black Hole Candidate GRS 1758-258
though X-ray Spectroscopy*

We present the results X-ray spectral study of the persistent
Galactic black hole X-ray binary GRS 1758-258. The data was observed
simultaneously by Swift and NuSTAR. Our spectral model fitting with an
absorbed power-law model revealed a broad Fe line and reflection hump
in the spectrum. We applied numerous flavours of the relativistic
reflection model for the spectral analysis. We cover the basic
accretion geometries for the models and provide brief introduction to
each of them. The spectral models suggests the spin of the black hole
is > 0.92. The source was in the low/hard state during the
observation, with the hot electron temperature of the corona estimated
to be kTe ~ 140 keV. The black hole is found to be accreting at ~ 1.5%
of the Eddington limit during the observation, assuming the black hole
mass of 10 solar mass and distance of 8 kpc.
(collaborators: Argha Jit Jana, Samar Safi-Harb, H K Chang, S Naik)

**Skye Heiland**,
Slides

*Long-term NICER Monitoring of Black Hole Low-mass X-ray Binary 4U
1755-338 *

Black Hole Low-mass X-ray Binaries (BH LMXBs) are among the most
important laboratories to study the extreme physics in the presence of
a deep gravitational well. They give rise to several important
phenomena observable primarily in the X-ray, namely Quasi-Periodic
Oscillations (QPOs) in X-ray flux and time-lags between energy
bands. Using two years of archival data from the Neutron Star Interior
Composition Explorer (NICER) we've been performing a comprehensive
investigation of the source 4U 1755-338 which began outbursting in
April, 2020 after a 24-year period of quiescence. We thus far report
the discovery of two probable Low Frequency QPOs around ~0.1 Hz
alongside a persistently soft spectral state. Future work will include
studying time/reverberation lags in greater detail, numerical
simulations to reproduce observational data of interest, and potential
direct mass measurements with collaborative observations in the
optical.

**Aaron Rossi**

*Phase Diagram of Reheating and Axion Inflation*

Reheating at the end of inflation provides an excellent backdrop to
study early universe particle production. The physics of reheating is
still very much an open question in physics research. My research
looks at the physics at the end of inflation using Floquet
analysis. Floquet analysis allows us to see how the axion field is
coupled to itself and the gauge field at the end of inflation. It also
allows us to look at energy densities at the end of inflation,
corresponding to particle production in the early universe. This
coupling allows us to create a phase diagram of the energy densities
to see which parameters allow for particle production in the early
universe for self resonance and gauge production.

**Kelvin Au**

*Investigating Plasma Lensing Structures by Simulating the Propagation of
Radio Wavefronts*

We simulate the propagation of radio wavefronts through spatially
varying continuous media to gain insight into the nature and
structure of plasma lenses thought to produce extreme scattering
events (ESEs). By first ray-tracing through spatially varying
media, we then construct the propagation of wavefronts. We form a
mapping between the source and the image to produce intensity
maps. With this approach, we have produced the resulting light
curves through turbulence generated by Fourier methods, as well as
turbulence generated using PythonMHD, an MHD simulation code
developed by Delica Leboe-McGowan at the University of
Manitoba. Future explorations of wavefront propagation through
plasma structures of various dimensionality such as spheres,
cylinders, and sheets are planned.

**Arghya Mukherjee**,
Slides

*Fermion propagator in presence of a strong external magnetic field*

A possibility of generation of an extremely strong magnetic field in
the ultra-relativistic heavy ion collision experiments at RHIC and
LHC, has encouraged the research interest in the magnetic
modifications of the quark gluon plasma properties. On the
theoretical side, the perturbative approach for the extraction of
thermodynamic properties, dispersion properties etc. requires the
evaluation of the Feynman loop diagrams. Thus, as a starting point of
such diagrammatic calculation in the presence of an external magnetic
field, one has to incorporate the magnetic field modifications in the
propagators. In this talk, the origin of such magnetic modification
in the fermion propagator and its consequences in the gluon
dispersion will be addressed.

**Neil Doerksen**

*The Neutron Star Merger: GW170817*

GW170817 is the first and only event to-date to be observed in both
gravitational and electromagnetic waves (from radio to high-energy
photons). This new multi-messenger event, discovered on Aug 17 (2017),
has generated a lot of interest among the astrophysics community
worldwide, and is an important milestone in astrophysical research. In
addition, while we know that this event resulted from two neutron
stars merging, the final mass of GW170817 puts it in the stellar
graveyard; that is to say, a mass region in between a neutron star and
a black hole where we observe almost no objects, but theory states
such objects should exist. This research is aimed at understanding the
aftermath of this neutron star merger by examining Chandra X-ray and
multi-wavelength/multi-messenger observations. We are particularly
interested in testing the GW170817 evolution against a kilonova
remnant model, in preparation for the next LIGO phase of observations.

**Kyle Monkman**

*Entanglement in topological insulators*

Explaining a complex topic such as "entanglement in topological
insulators" is extremely difficult, even when the audience has
relative expertise in the topic. In my presentation, I will try to
build on a topic that students already know. That is; a particle in a
box. I will use the "particle in a box" concept to separately discuss
topology, insulating materials and entanglement. At the end, I will
try to bring them all together to understand my project.

**Bryce Friesen**

*Early Time Dynamics in Heavy Ion Collisions*

When a particle accelerator is used to make a high energy collision
between two heavy nuclei, a plasma is formed. This plasma can be
analyzed to examine the behaviour of quarks and gluons. We do this by
calculating the electric and magnetic fields surrounding the
plasma. These fields are analyzed to produce an approximation using a
technique called expanding in proper time. This analysis yields very
large equations. As we attempt to solve these equations at times
increasingly further away from the time of collision, computations
slow down so much that the process becomes unviable with existing
methods. Our work focuses on developing computational methods to
speed up the analysis. Specifically, we are focusing on the use of
the Julia programming language to make the computation feasible.

**Tom Friesen**

Continuation of Bryce Friesen's talk topic

**Hermie Monterde**,
Slides

*State transfer on weighted graphs with twin vertices*

Twin vertices in a graph are vertices with the same neighbourhood. In
this talk, we examine the types of state transfer exhibited by graphs
with twin vertices.

**Rodrigo Alves Pimenta**

*Free fermionic and parafermionic quantum spin chains*

We
will discuss a new family of quantum spin chains with multispin
interactions whose spectrum has a free fermionic or parafermionic
nature. Despite the free nature of the spectrum, these spin chains in
general cannot be solved by the Jordan-Wigner transformation. However,
exploiting integrability, it can be shown that the quasi-energies are
related to the roots of certain characteristic polynomials given by
higher-order recurrence relations. In particular, the so-called
Laguerre bound for the largest root of the characteristic polynomial
allows a very efficient computation of the mass gap, providing a
relevant tool for the study of critical quantum chains with and
without quenched disorder. Beyond the spectral level, many interesting
aspects of the Hamiltonians remain to be understood, for example, the
computation of correlation functions and entanglement entropy.

**Guillaume Payeur**

*Completely Dark Dark Matter & the de Sitter Swampland
Conjecture*

**Naman Agarwal**,
Slides

*Holographic Complexity and Extra Dimensions*

Abstract

**Jesse Elder**,
Slides (powerpoint)

*Quantum Field Theory in Curved Spacetime*