Calvin Leung

I am a Miller Fellow and former NASA Einstein Fellow at UC Berkeley in the Department of Astronomy. I am a member of the CHIME/FRB Collaboration, and did my PhD in physics at MIT with Kiyo Masui.

Instrumentation: Since 2018 I've been playing a leading role in the CHIME/FRB Outriggers Project. I designed and built the VLBI backend for the outrigger stations, and wrote most of the reduction pipeline, including a VLBI correlator and astrometric VLBI calibration and reduction pipeline. Due to these efforts CHIME/FRB now dominates the observational FRB landscape: with the highest detection rate and exquisite localization accuracy for hundreds of sources per year.

Observations: I am interested in ultra-wide field VLBI, and using FRBs as probes of the ISM, CGM, and baryonic feedback in cosmology, particularly in the context of upcoming weak-lensing surveys like Euclid and LSST. I have published the first constraints on primordial black holes using FRB lensing, as well as one of the first FRB-based constraints on sub-grid models for stellar and AGN feedback. I am a key player in single-source science enabled by CHIME/FRB Outriggers, including the first FRB localized to a massive elliptical host, and the first one-off FRB localized to 13 parsec accuracy.

Theory: I am interested in interstellar optics like gravitational and plasma lensing, radio-wave scintillation and scattering, and wave optics/diffraction in gravitational lensing. Lately, I have been working with hydrodynamical simulations of galaxy clusters.

Email me at [three-letter acronym for fast radio burst] [at symbol] mit.edu

References

First and co-first author papers

I am interested in fast radio bursts, VLBI instrumentation and astrometry, the CGM and ISM, baryonic feedback in large-scale structure, and interstellar optics.

1. Stellar Mass-Dispersion Measure Correlations Constrain Baryonic Feedback in Fast Radio Burst Host Galaxies
   
   [arXiv:2507.16816] Submitted.
2. A Catalog of Local Universe Fast Radio Bursts from CHIME/FRB and the KKO Outrigger
   
   [arXiv:2502.11217] The Astrophysical Journal Supplement.
3. A VLBI Software Correlator for Fast Radio Transients
   
   [arXiv:2403.05631] The Astronomical Journal.
4. A fast radio burst localized at detection to a galactic disk using very long baseline interferometry
   
   [arXiv:2307.09502] Nature Astronomy (corresponding author); co-led with Tomas Cassanelli and Pranav Sanghavi)
5. Wave Optics, Interference, and Decoherence in Strong Gravitational Lensing
   
   [arXiv:2304.01202] Springer Space Science Reviews.
6. Constraining Primordial Black Holes using Fast Radio Burst Gravitational-Lens Interferometry with CHIME/FRB
   
   [arXiv:2204.06001] Physical Review D.
7. A High-Time Resolution Search for Compact Objects using Fast Radio Burst Gravitational Lens Interferometry with CHIME/FRB
   
   [arXiv:22204.06014] Physical Review D; co-led with Zarif Kader.
8. A Synoptic VLBI Technique for Localizing Non-Repeating Fast Radio Bursts with CHIME/FRB
   
   [arXiv:2008.11738] The Astronomical Journal.
9. Testing the Weak Equivalence Principle using Optical and Near-Infrared Crab Pulses
   
   [arXiv:1804.04722] The Astrophysical Journal.
10. Astronomical random numbers for quantum foundations experiments
    
    [arXiv:1706.02276] Physical Review A.
11. Measuring the spatial resolution of an optical system in an undergraduate optics laboratory
    
    [Available from Am J Phys]
12. Estimation of Unmodeled Gravitational Wave Transients with Spline Regression and Particle Swarm Optimization
    
    [Available from SIAM Undergraduate Research Online]

Student-Led Papers

My goal is that every student who works with me as a primary supervisor can eventually lead at least one first-author science paper. Mostly I work on observations, data analysis, and instrumentation, but no background using any particular set of tools is necessary. I work well with students who are curious and eschew a ``black box'' approach to physics and astronomy. If you are interested in working with me please shoot me an email! Here are some examples of student papers.

1. Accretion from a Shock-Inflated Companion: Spinning Down Neutron Stars to Hour-Long Periods
   
   [arXiv:2507:10682] Submitted; led by Savannah Cary (Berkeley); co-supervised with Wenbin Lu
2. A repeating fast radio burst source in the outskirts of a quiescent galaxy
   
   [arXiv:2410.23374] Astrophysical Journal Letters; led by graduate mentee, Vishwangi Shah (McGill)
3. A VLBI Calibrator Grid at 600MHz for Fast Radio Transient Localizations with CHIME/FRB Outriggers
   
   [arXiv:2409.11476] The Astronomical Journal; led by graduate mentee, Shion Andrew (MIT)
4. Scintillation Timescales of Bright FRBs Detected by CHIME/FRB
   
   [arXiv:2111.08753] Research Notes of the American Astronomical Society; led by undergraduate mentee Eve Schoen (MIT class of 2022; now PhD candidate at Berkeley Physics)
5. Evaluating and Enhancing Candidate Clocking Systems for CHIME/FRB VLBI Outriggers
   
   [arXiv:2109.05044] Research Notes of the American Astronomical Society; led by undergraduate mentee Savannah Cary (Wellesley class of 2022; now PhD candidate at Berkeley Astro)

Other (contributing author) Papers

I take pride in playing a strong supporting role to my colleagues, many of whom have become my close friends.

1. FRB 20250316A: A Brilliant and Nearby One-Off Fast Radio Burst Localized to 13 parsec Precision
   
   [arXiv:2506.19006] CHIME/FRB Collaboration, incl. Calvin Leung, et al. (2025).
2. Investigating the sightline of a highly scattered FRB through a filamentary structure in the local Universe
   
   [arXiv:2410.07307] Kaitlyn Shin, Calvin Leung, et al. (2024).
3. TONE: A CHIME/FRB Outrigger Pathfinder for localizations of Fast Radio Bursts using Very Long Baseline Interferometry
   
   [arXiv:2110.13920] Pranav Sanghavi, Calvin Leung, et al. (2024).
4. Axion dark matter-induced echo of supernova remnants
   
   [arXiv:2110.13920] Yitian Sun, et al. including Calvin Leung (2021).
5. Localizing FRBs through VLBI with the Algonquin Radio Observatory 10-m Telescope
   
   [arXiv:2107.05659] Tomas Cassanelli, Calvin Leung et al. (2021).
6. A clock stabilization system for CHIME/FRB Outriggers
   
   [arXiv:2110.00576] Juan Mena-Parra, Calvin Leung et al. (2021).

Papers outside astrophysics

Selected papers from my past life outside astrophysics, on the Cosmic Bell test, and on using laser spectroscopy to search for dark matter.

1. Evidence of Two-Source King Plot Nonlinearity in Spectroscopic Search for New Boson
   
   [arXiv:2201.03578]
   (PRL)
2. Evidence for Nonlinear Isotope Shift in Yb+ Search for New Boson
   
   [arXiv:2004.11383]
   (PRL)
3. Cosmic Bell Test Using Measurement Settings from High-Redshift Quasars
   
   [arXiv:1808.05966]
   (PRL)
4. Cosmic Bell Test: Measurement Settings from Milky Way Stars
   
   [arXiv:1611.06985]
   (PRL)

Music and Random Stuff