Casey Lam

Graduate Student, UC Berkeley Astronomy

Electronic: casey under$c0r3 lam a7 berkeley d0t 3du*
Snails: 501 Campbell Hall, Berkeley, CA 94720-3411
*Insert appropriate symbols, this is my attempt at foiling spambots.

About me

I am a finishing PhD candidate (graduating 2023) in the Department of Astronomy at UC Berkeley, where I work with Professor Jessica Lu to use gravitational microlensing to detect stellar mass black holes in the Milky Way. I earned my bachelor's degree in math and physics (and also a pirate's license) at MIT.

A slightly longer biography can be found here.

A PDF of my CV (current as of July 2022) can be found here.


Research projects and interests

An isolated mass gap black hole or neutron star detected with astrometric microlensing

By combining ground-based photometry from the OGLE and MOA microlensing surveys with archival HST follow-up observations, we measure the lens masses of five microlensing black hole candidates. In addition, we identify the nature of the lenses (whether brown dwarf, star, white dwarf, neutron star, or black hole). We then constrain the number of black holes in the Milky Way. In particular, we find that one of the candidates (OGLE-2011-BLG-0462/MOA-2011-BLG-191) is possibly a neutron star or mass-gap black hole; the remaining candidates are not black holes. Finding 0 or 1 black holes in this sample is consistent with 100 million black holes in the Milky Way.

Get the published papers here: Astrophysical Journal Letter, companion Astrophysical Journal Supplement

PopSyCLE (Population Synthesis for Compact object Lensing Events)

I was the primary developer for PopSyCLE v1.0.0, a Milky Way microlensing simulation code. PopSyCLE can be used to simulate microlensing surveys in the Milky Way, as well as identifying optimal strategies for selecting black hole candidates for astrometric follow up. In particular, we present an new selection criteria to photometrically identify black hole candidates via their small microlensing parallaxes.

Get the published paper (Astrophysical Journal) here.

The code repository for the simulation can be found on GitHub. PopSyCLE is still being actively developed and we welcome contributions.

Black hole microlensing with the Roman Space Telescope

The Nancy Grace Roman Space Telescope is NASA's next flagship mission, scheduled for launch around 2027. One of Roman's mission objectives is to perform a census of cold and free-floating exoplanets via the Galactic Bulge Time Domain Survey with microlensing. This survey is will also be an excellent way to detect a large sample of free-floating black holes. However, the optimal survey design for making black hole detections likely differs from that for making exoplanets detections. I am working to understand what auxiliary observations or survey design changes could optimize the measurement of free floating black holes with minimal change to the exoplanet yield. I am also interested in what Roman can do in conjunction with other observatories (e.g. Rubin Observatory's LSST).

Research papers

My full publication record can be found on ADS, ORCID, or arXiv.


Notes

Brief calculus review notes I put together for my Astro 7B discussion section.
Chain Rule
Taylor Series

Brief notes I put together for my Astro 7A students.
Angular Distance and Area
Divergence of the partition function for hydrogen


Following in the tradition of other great academic webpages, here is an outdated photo of myself.