Small Scale Lensing
I'm currently working with Prof. Renée Hložek (Dunlap Institute) as well as Alexander van Engelen (Canadian Institute for Theoretical Astrophysics) and Joel Meyers (Southern Methodist University) on creating an estimator for the effects of weak gravitational lensing on the cosmic microwave background (CMB) at small angular scales (l > 3000). The basic principle of the estimator is to construct local statistics for the small scale temperature power and average temperature gradient for small patches across the sky. By matching these two quantities together for many patches across the sky, this allows us to infer a global small scale lensing effect. Measurements of the lensing convergence power at these scales are at the moment unexplored, and present an opportunity to constrain cosmological models that affect matter clustering (e.g., fuzzy dark matter, massive neutrinos, etc.). This method shows particular potential in its indifference to noise/foregrounds that do not correlate with the background temperature gradient. Feel free to send me an e-mail if you are interested in this work!
Figure 1: These slopes of these lines represent the amount of lensing in a CMB temperature map. The top panel shows the results from a simulated CMB temperature map WITHOUT lensing. The bottom panel shows the results from the same simulated CMB temperature map WITH lensing. The non-zero slope in the bottom panel clearly shows that weak lensing is creating a correlation between small scale temperature fluctuations in the CMB and the large scale backgroung temperature gradient.
Gaia Zero-Point Parallax
This is a short project under the supervision of Prof. Jo Bovy (University of Toronto). The Gaia satellite released parallax measurements for nearly 2 billion sources with its second data release in April 2018. It was also reported that these measurements all have a systematic offset of order ~10s µas. We construct a probabilistic model relating the luminosity of red clump stars to their expected parallaxes, and apply it to a cross-match of Gaia DR2 and the APOGEE red clump catalog. We find a significant zero-point of approximately 49 µas to a precision of 1 µas. Current work is being done to probe the colour, temperature, and magnitude dependence of this zero-point, and a paper is being written for submission. You can click here to learn more.
LiteBIRD
This is an ongoing project with Prof. Renée Hložek (Dunlap Institute), Matt Dobbs (McGill University), and Joshua Montgomery (McGill University) to simulate the effects of detector readout systematics for the upcoming LiteBIRD satellite. We use the TOAST software to simulate the satellite observation process from detector pointing, generating timestreams, and finally mapmaking. I have altered the TOAST simulation pipeline to account for the effects of detector crosstalk, a process by which signals destined for certain detectors are received/recorded by others. We investigate the effects of various forms of crosstalk introduced by the configuration of the readout electronics, and preliminary results have been presented at the LiteBIRD F2F/B-modes from Space conference at MPA in December 2019.
Pulsar Lensing
For my undergraduate dissertation, I worked with Prof. Keith Vanderlinde (Dunlap Institute) and the pulsar scintillometry group at the University of Toronto/CITA on an analysis of the eclipses of the Black Widow Pulsar, B1957+20. This is a pulsar binary in which a brown dwarf is known to eclipse the pulsar roughly once every 9 hours. It was known that the observed pulsar signal seems to be intensely magnified at times just before and after eclipses. Our project culminated in a successful demonstration that the apparent pulsar magnification was a result of extreme lensing events. I was also able to measure a sizeable increases in the dispersion measure of the observed signal, which were a result of the ablation of the pulsar's companion. In these measurements, consistent small scale structure in the extra electron column depth could be observed embedded in a large scale fluctuation (See below). The pulsar scintillometry group at CITA has been using these results learn much more about the system. The full results have been published here.
Figure 2: As the Black Widow pulsar comes out of eclipse, you can observe a significant increase in the electron column density along our line of sight. Embedded within this large scale fluctuation, you can see much smaller structures that are picked up by all three of the observation bands in the figure.
Papers & Presentations
Here are my past papers, presentation slides, and posters in reverse chronological order.
Dec 2019: Determining the Observational Effects of Detector Crosstalk through Simulation - Poster for B-Modes from Space conference at MPA
Oct 2019: The Gaia DR2 parallax zero point: Hierarchical modeling of red clump stars - Manuscript submitted to MNRAS
July 2019: Gaia Systematics and the Hubble Constant - Presentation for Hubble Tensions conference at KITP
Jun 2019: Probabilistic Modeling of Gaia DR2 Systematics - Poster for CASCA Annual General Meeting (Click here for more info)
Dec 2018: Small Scale CMB Lensing with Local Map-Space Statistics - Presentation for CMB in HD workshop at the CCA
May 2018: Pulsar emission amplified and resolved by plasma lensing in an eclipsing binary - Letter to Nature (arXiv:1805.09348)
May 2018: Estimating the Effects of Weak Gravitational Lensing on the Cosmic Microwave Background using Local Statistics - Poster for CASCA Annual General Meeting