Massive Galaxies in the Distant Universe

Caitlin Casey's Research Page

I am an observational astronomer specializing in extragalactic astrophysics. Historically I have focused primarily on dust-obscured star-formation and gas-enrichment of galaxies across cosmic time. More recently, I have expanded to study early Universe galaxies (z>5), their large scale environment, and impact on our understanding of the Universe's first billion years.

The Distant Universe

I am PI of both the COSMOS-Web Survey (the largest JWST Cycle 1 program) and the COSMOS Survey along with Prof. Jeyhan Kartaltepe at RIT. COSMOS-Web is a 0.6deg^2 NIRCam imaging program, with 0.2deg^2 MIRI imaging collected in parallel, with the goal of revealing the sources of cosmic reionization. Data collection will happen from December 2022 through April 2023. I am currently hiring postdocs and graduate students to come work on COSMOS-Web, so please contact me if interested.

Listen to me explain the exciting JWST science we'll do on the Vox Unexplainable Podcast, or read about it on Vox here and here. I've also enjoyed talking about JWST on NPR's All Things Considered, NPR's 1A Program, the Marketplace Make Me Smart Podcast, the Texas Standard (NPR program for state of Texas), and been profiled by the Texas Monthly and Austin Monthly magazines. Time allowing, I am happy to be contacted for additional media appearances regarding JWST and the distant Universe.

The Obscured Universe

Instrumental limitations have restricted galaxy evolution resesarch to optical and near-infrared wavelengths for several decades, biasing our view of the distant Universe to unobscured starlight. Thanks to innovative millimeter-wave technology of the past few years, it is now possible to probe galaxies’ dust and gas directly, both playing an essential role in the growth of galaxies within large-scale cosmic web. I have expertise at both optical/near-infrared and submillimeter through radio wavelengths, and I use multiwavelength observations to interpret gas and dust tracers from the local Universe back to the first galaxies 13 billion years ago. These tracers have indicated much of what we have learned from galaxies’ starlight is biased and potentially inaccurate. In addition, I use these unique dust and gas tracers to learn about the collapse of large scale structure within the first few billion years after the Big Bang.

Watch my Newton Lacy Pierce Prize Lecture on The Obscured Early Universe at the 233rd AAS Meeting HERE.

Watch my plenary lecture at the 230th AAS Meeting on The Universe's Most Extreme Star-Forming Galaxies HERE.

Focus & Goals

The immediate aims of my research group are to address the following questions:
  • are massive galaxies predominantly built through catastrophic galaxy mergers, or isolated processes?
  • do massive galaxies reionize the universe?
  • are the first massive galaxies highly clustered? how do they evolve toward z=0?
  • are massive galaxy clusters built up in periods of rapid filamentary collapse, or steady increased growth?
  • are the first galaxies in the Universe dust-free?
  • are galaxy mergers an important catalyst for the build-up of stellar mass in the Universe?
  • how will current and future deep dust and gas surveys in the high-redshift Universe change our existing picture of galaxy evolution, as developed from predominantly optical and near-infrared observations?

Research Group Members

Please visit our group page to learn more about each member and their work!

Publications from the Group

  • Casey et al. (2022) ApJ submitted
    The COSMOS-Web Survey: An Overview of the JWST Cosmic Origins Survey, ADS Link
  • Zavala et al. (2022b) ApJ submitted
    A dusty starburst masquerading as an ultra-high redshift galaxy in JWST CEERS Observations, ADS Link
  • Long et al. (2022) ApJ submitted
    Missing Giants: Predictions on Dust-Obscured Galaxy Stellar Mass Assembly Throughout Cosmic Time, ADS Link
  • Zavala et al. (2022a) ApJ 933, 242
    Probing Cold Gas in a Massive, Compact Star-forming Galaxy at z=6, ADS Link
  • Drew & Casey (2022) ApJ 930, 142
    No Redshift Evolution of Galaxies’ Dust Temperatures Seen from 0 < z < 2, ADS Link
  • Cooper et al. (2022) ApJ 930, 32
    Searching Far and Long. I. Pilot ALMA 2mm Follow-up of Bright Dusty Galaxies as a Redshift Filter, ADS Link
  • Manning et al. (2022) ApJ 925, 23
    Characterization of Two 2mm detected Optically Obscured Dusty Star-forming Galaxies, ADS Link
  • Casey et al. (2021) ApJ 923, 215
    Mapping Obscuration to Reionization with ALMA (MORA): 2 mm Efficiently Selects the Highest-Redshift Obscured Galaxies, ADS Link
  • Champagne et al. (2021) ApJ 913, 110
    Comprehensive Gas Characterization of the z=2.5 Protocluster: A Cluster Core Caught in the Beginning of Virialization?, ADS Link
  • Burnham et al. (2021) ApJ 910, 89
    The Physical Drivers of the Luminosity-weighted Dust Temperatures in High-Redshift Galaxies, ADS Link
  • Zavala et al. (2021) ApJ 909, 165
    The Evolution of the IR Luminosity Function and Dust-obscured Star Formation over the Past 13 Billion Years, ADS Link
  • Premnath, Spilker, Casey & Gurwell (2020) RNAAS 4, 173
    Evidence for a Buried AGN in an Extremely Bright Dusty Galaxy at z = 2, IOP Link
  • Casey (2020) ApJ 900, 68
    Far-Infrared Photometric Redshifts: A New Approach to a Highly Uncertain Enterprise, ADS Link
  • Manning et al. (2020) MNRAS 495, 1724
    SuperCLASS - II. Photometric redshifts and characteristics of spatially resolved μJy radio sources, ADS Link
  • Drew et al. (2020) ApJ 892, 104
    Three Dusty Star-forming Galaxies at z~1.5, ADS Link
  • Zavala et al. (2019) ApJ 887, 183
    On the Gas Content, Star Formation Efficiency, and Environmental Quenching of Massive Galaxies in Protoclusters at z~2.0-2.5, ADS Link
  • Casey et al. (2019) ApJ 887, 55
    Physical Characterization of an Unlensed, Dusty Star-forming Galaxy at z=5.85, ADS Link
  • Urias, Zavala & Casey (2020) RNAAS, 3, 140
    Characterizing a Dusty Star-forming Galaxy at z~3, IOP Link
  • Casey et al. (2019) Bulletin of the AAS, 51 212 (arxiv/1903.05634)
    Taking Census of Massive, Star-Forming Galaxies formed <1Gyr After the Big Bang, ADS Link
  • Wicker & Casey (2019) RNAAS, 3, 83
    Constraining Multiplicity and Clustering Using Empirical Models of the (Sub)Millimeter Sky, IOP Link
  • Schechter & Casey (2018) RNAAS 2, 4
    Examining the Gas Outflow for a Typical Dusty Star-forming Galaxy at z=2, IOP Link
  • Zavala et al. (2018) ApJ in press
    Constraining the volume density of Dusty Star-Forming Galaxies through the first 3mm Number Counts from ALMA, ADS Link
  • Drew et al. (2018) ApJ in press
    Evidence of a Flat Outer Rotation Curve in a Starbursting Disk Galaxy at z=1.6, ADS Link
  • Champagne et al. (2018) ApJ 867, 153
    No Evidence for Millimeter Continuum Source Overdensities in the Environments of z>6 Quasars, ADS Link
  • Casey et al. (2018b) ApJ 862, 78
    An Analysis of ALMA Deep Fields and the Perceived Dearth of High-z Galaxies, ADS Link
  • Casey et al. (2018a) ApJ 862, 77
    The Brightest Galaxies in the Dark Ages: Galaxies' Dust Continuum Emission During the Reionization Era, ADS Link
  • Casey et al. (2017) ApJ 840, 101
    Near-Infrared MOSFIRE Spectra of Dusty Star-Forming Galaxies at z<4, ADS Link
  • Hung et al. (2016) ApJ 826, 130
    Large-Scale Structure around a z=2.1 Cluster, ADS Link
  • Casey (2016) ApJ 824, 36
    The Ubiquity of Coeval Starbursts in Massive Galaxy Cluster Progenitors, ADS Link
  • Casey et al. (2015) ApJL 808, 33
    A Massive, Distant Protocluster at z=2.47 Caught in a Phase of Rapid Formation?, ADS Link

Caitlin Casey's First Authored Publications before joining UT Austin:
  • Casey et al. (2014) ApJ 796, 95
    Are Dusty Galaxies Blue? Insights on UV Attenuation from Dust-selected Galaxies, ADS Link
  • Casey, Narayanan & Cooray (2014) Physics Reports 541, 45
    Dusty Star-Forming Galaxies at High Redshift, ADS Link
  • Casey et al. (2013) MNRAS 436, 1919
    Characterization of SCUBA-2 450um and 850um selected galaxies in the COSMOS field, ADS Link
  • Casey et al. (2012c) ApJ 761, 139
    A Population of z>2 Far-infrared Herschel-SPIRE-selected Starbursts, ADS Link
  • Casey et al. (2012b) ApJ 761, 140
    A Redshift Survey of Herschel Far-infrared Selected Starbursts and Implications for Obscured Star Formation, ADS Link
  • Casey (2012) MNRAS 425, 3094
    Far-infrared spectral energy distribution fitting for galaxies near and far, ADS Link
  • Casey et al. (2011b) MNRAS 415, 2723
    Molecular gas in submillimetre-faint, star-forming ultraluminous galaxies at z>1, ADS Link
  • Casey et al. (2011a) MNRAS 411, 2739
    Spectroscopic characterization of 250um-selected hyper-luminous star-forming galaxies, ADS Link
  • Casey et al. (2009c) MNRAS 400, 670
    A search for neutral carbon towards two z=4.05 submillimetre galaxies, GN20 and GN20.2, ADS Link
  • Casey et al. (2009b) MNRAS 399, 121
    Confirming a population of hot-dust dominated, star-forming, ultraluminous infrared galaxies at high-redshift, ADS Link
  • Casey et al. (2009a) MNRAS 395, 1249
    Constraining star formation and AGN in z~2 massive galaxies using high-resolution MERLIN radio observations, ADS Link
  • Casey et al. (2008b) ApJS 177, 131
    Optical Selection of Faint Active Galactic Nuclei in the COSMOS Field, ADS Link
  • Casey et al. (2008a) AJ 136, 181
    PC 1643+4631A, B: the Lyman-alpha Forest at the Edge of Coherence, ADS Link