About me

I'm a PhD student at Caltech working with Prof. Chuck Steidel to study the physical conditions in star-forming galaxies at redshifts 2-3 with the Keck Baryonic Structure Survey (KBSS). We're using complementary rest-optical and rest-UV spectra from the MOSFIRE and LRIS spectrographs on the Keck 10 m telescope to simultaneously constrain the stellar and nebular properties of these galaxies. In particular, we're looking to characterize stellar and nebular abundances, ISM kinematics and dynamics, and dust attenuation.

I also enjoy engaging in astronomy outreach, sharing my work with the public and encouraging children to pursue careers in STEM fields. I recently gave a public talk through Caltech's Stargazing Lecture series, which is available to view on YouTube.

In my spare time, I run the Caltech Ballet Club, which offers weekly ballet classes for both Caltech students and the broader community. Check out our website!


  • The Keck Baryonic Structure Survey

    The KBSS is comprised of 15 independent fields, each of which is centered on one of the brightest optical quasars in the sky. High-resolution spectroscopy of the central QSOs provides detailed information about the IGM and CGM along each QSO sightline. The galaxies are selected from deep optical and near-infrared imaging so as to provide a large dynamic range of galaxy properties, and followed up with spectroscopy in the rest-UV from Keck/LRIS and in the rest-optical from Keck/MOSFIRE.

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  • The KBSS-LM project

    In late 2014, our research group began a new observing program using LRIS-B+R to follow up a representative subset of the full KBSS-MOSFIRE dataset with complete nebular emission line measurements in the J, H, and K bands, in order to construct a more homogeneous rest-UV data set designed to be used simultaneously with the MOSFIRE spectra. This sample of galaxies with high-quality spectra from both MOSFIRE and LRIS-B+R is referred to as KBSS-LRIS/MOSFIRE (KBSS-LM). Steidel et al. (2016) conducted a pilot survey, referred to as "KBSS-LM1," using initial observations with the first two KBSS-LM slitmasks. The bulk of my thesis work will be focused on the full KBSS-LM sample, consisting of ~185 galaxies. The goal is to develop a self-consistent framework incorporating photoionization modeling, stellar population synthesis model fitting, and SED fitting in order to simultaneously constrain the stellar and nebular properties of the same galaxies.

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  • Dust attenuation, metallicity, and SFRs

    In Theios et al. (2019), I use a set of ~300 complementary rest-optical and rest-UV spectra, along with SED fitting to broadband photometry, to examine stellar and nebular dust attenuation, parameterized by the reddening E(B-V), for the same galaxies. I examine trends between dust attenuation and metallicity, and I use comparisons of SFRs estimated by different means to constrain the stellar and nebular dust attenuation curve. Finally, I compare SED-based SFRs to those estimated from H-alpha for the same galaxies.

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  • ISM kinematics and dynamics

    In an upcoming paper, I focus on utilizing the wealth of interstellar absorption lines apparent in the rest-UV spectra of z~2 galaxies, combined with information from nebular emission lines visible in rest-optical spectra, in order to study the kinematics of galaxy-wide outflows.