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Joseph Hollowed

Student Researcher in Cosmological Physics
Chicago, IL

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forked from Sérgio Kopplin

Detailed below are several of my current and past scientific research endeavors, as well as general academic and recreational projects. Presentation slide decks can also be found for some of the research described here in my list of scientific talks.


Most of my work resides in theoretical and computational cosmology, working on both analysis and modeling tasks.

We currently find ourselves in an exciting age, wherein we see petascale astronomical data releases on the horizon, thanks to extensive sky surveys like DES and LSST. With these unprecedented data volumes, statistical uncertainties are falling to sub-percent levels, leaving our analyses dominated by systematics errors. Thus, the community is now tasked with producing very accurate models of astrophysical and cosmological systems. Working toward this goal, as it turns out, is great fun, and calls for supercomputers to run the largest and most detailed simulations of the universe's evolution to date. It is this that motivates my work showcased here, and inspires my daily musings.
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I am currently working on development of HACC (Hybrid/Hardware Accelerated Cosmology Code) simulation components and analysis codes at CPAC. My primary focus as of late has been writing tools to generate simulation lightcone datasets, from which to later extract mock telescope fields of view. The technical details of the former can be found in an extensive set of notes on lightcone construction, and the latter, on my associated GitHub repo.
This work contributes to the creation of DC2 synthetic galaxy catalogs for the LSST DESC, designed to prepare analysis pipelines for LSST first-light. Looking forward, I am working toward a calibration of the weak-lensing derived galaxy cluster masses (see my talk from 2018 for a sample).
Previously, I have worked on cluster cosmology projects, concentrating on velocity-dispersion-mass scaling relations, and using this as a metric by which to validate the above mentioned synthetic catalogs. See my talks from 2017 and 2016 to see a sample of this work, and read my unofficial paper on the subject for full details.
All of my code products from everything I've worked on at CPAC are maintained on GitHub.

Other Projects

I also like to maintain a number of creative activities, namely photography and videography. In keeping with the theme of this site, below is a brief gallery of some of my (mostly) widefield astrophotography, including a few video samples. Beyond this, visitors are welcome to check out my Vimeo and Instagram profiles.