My research interests center on the formation and evolution of galaxies across cosmic time. I am pursuing several avenues,
which range from detailed studies to understand the physical processes in galaxies, to large photometric and spectroscopic
surveys to examine how galaxies evolve over time, to improving the tools and techniques used to study galaxies.
Below are external links to my major research programs and publications, as well as research highlights of my group.
New pathways to studying galaxy growth
In the past decade, large and deep photometric and spectroscopic surveys have significantly advanced our
understanding of galaxy growth, from the most active time in the universe (z=2ā3) to the present day.
My group has worked on several new approaches to push this field forward. First, we used half-mass (instead
of half-light) radii combined with a clustering-based classification method, to understand how galaxies grow
during the star-forming and quiescent phase. This work is featured in four papers by former
Berkeley graduate student Wren Suess (Suess, Kriek, Price, & Barro
2019A,
2019b,
2020,
2021). Second, we
presented a large comprehensive study of the kinematic evolution of star-forming galaxies over cosmic
time (z~1.4-3.8). This work used a new approach based on randomly oriented slit observations from the MOSDEF survey
and a comprehensive forward modeling technique based on HST imaging, and is featured in two papers
by former Berkeley graduate student Sedona Price (Price et al.
2016,
2020). Over the
coming years we will apply this new approach to distant quiescent galaxies in our
Heavy Metal survey
and JWST/NIRSpec
program, to further unravel their kinematic evolution.
Chemical footprints
Chemical compositions of galaxies enable a unique view into their chemical enrichment, star formation and
assembly histories. While metallicities of star-forming galaxies have been studied out to z~4 using bright emission lines,
this work is probitively challenging for distant quiescent galaxies for which we rely on faint absorption lines shifted
to near-IR wavelengths. Nonetheless, my group has significantly advanced this field over the past few years.
To obtain a full evolutionary senses, we are using the public SDSS and LEGA-C surveys at lower redshifts
(Beverage et al. 2021, 2023), and Keck Observatory
(MOSFIRE &
LRIS) at higher redshifts (Kriek et al. 2016,
2019).
By studying the stellar ages and elemental abundances in relation
to other galaxy poperties, such as mass and size, we are learning (i) when, how fast, and how efficient quiescent galaxies formed
their star and enriched their gas (ii) why they stopped forming stars, and (iii) how they evolved after becoming quiescent. Over the coming years we will use the
ultra-deep spectra from the Heavy Metal survey and from our
JWST/NIRSpec program
to fully exploit the use of metals for understanding the formation histories of quiescent galaxies.
Galaxy transformations
We have known for more
than a century that galaxies come in two flavors: spiral galaxies with high stellar birth rates and more
massive elliptical galaxies with quiescent stellar populations. Nonetheless, the processes by which star-forming
disks transform into quiescent ellipticals are poorly understood. My group is tackling this problem using
several approaches. First, we use massive post-starburst galaxies at z=0.5-1.0 as
laboratories for understanding this transformation (SQuIGGLE;
Suess et al. 2022) and showed that galaxies with recently suppressed star formation
can still host large molecular gas reservoirs (Suess et al. 2017 ).
Second,
we studied the molecular gas and kinematic properties of compact star-forming galaxies, catching the phase just
before the star formation is quenched (Barro et al.
2016;
2017).
Finally, we unravelled the structural transformation
during the transitional phase by combining stacked spectra from the MOSDEF survey
or composite spectral energy distributions with structural properties of galaxies
(Yano et al. 2014;
Zick et al. 2018,
Suess et al. 2021).
Over the coming years, the Heavy Metal survey, our
JWST/NIRSpec program, and new ALMA
observations will further advance this field.
Toward more accurate measurements and model ingredients
Whereas studies of the distant galaxy population have grown tremendously in both size and depth over the past years,
scientific progress has been
limited by severe systematic uncertainties. Deriving physical properties from galaxy observations strongly relies on
stellar population synthesis and dust models, as well as empirical calibrations.
Such models and calibrations rely on many assumptions
regarding stellar evolution, the initial mass function, stellar binary populations, chemical abundance patterns,
dust geometry, etc. Over the past decade, my group has focused on improving our understanding of many of these
ingredients, ranging from the thermally-pulsing AGB phase, the dust attenuation law, star formation rate
indicators, to (X-ray)-binary populations (e.g., Kriek et al.
2010,
2013;
Price et al. 2014;
Utomo et al. 2014;
van de Sande et al. 2015;
Fornasini et al. 2019).
Furthermore, using cosmological simulations we have assessed how
well our current analysis methods can measure the sizes and masses of distant galaxies
(Price et al. 2018).
