I am a Professor of Extragalactic Astronomy at Leiden Observatory
My research group studies how galaxies,
including our own Milky Way, came into existence. In order to unravel their formation histories, we examine masses,
sizes, ages, stellar birth rates, stellar motions, chemical compositions, black hole signatures,
and many more properties of galaxies over cosmic time. I started at Leiden Observatory in the summer of 2021.
Previously, I was a Professor (Assistant, Associate, and Full) in the Astronomy Department at
UC Berkeley (2012-2022),
a Clay Postdoctoral Fellow at the Harvard-Smithsonian Center for Astrophysics (2010-2011),
and an H. N. Russell Postdoctoral Fellow at Princeton University (2007-2010).
I obtained my Ph.D. at Leiden Observatory in 2007, working with Professors Pieter van Dokkum
at Yale and Marijn Franx at Leiden.
- Job opening in our group:
Postdoctoral position in extragalactic astronomy (AAS job register)
- New publication:
Elemental Abundances and Ages of z∼0.7 Quiescent Galaxies on the Mass-Size Plane: Implication for Chemical Enrichment and Star-Formation Quenching
Beverage, A. G., Kriek, M., Conroy, C., Bezanson, R., Franx, M., & van der Wel, A. 2021, ApJ, 917, L1
- New publication:
Dissecting the Size-Mass and Σ1-Mass Relations at 1.0 < z < 2.5: Galaxy Mass Profiles and Color Gradients as a Function of Spectral Shape
Suess, K. A., Kriek, M., Price, S. H., & Barro, G. 2021, ApJ, 915, 87
- Appoved JWST Cycle 1 proposal:
Ultra-deep continuum spectroscopy of quiescent galaxies at 1.0 < z < 2.5: chemical abundances and stellar kinematics
PI: Kriek / co-PI: Beverage
Current group members:
Former PhD students:
- Aliza Beverage, UCB PhD student (2025)
- Brian Lorenz, UCB PhD student (2025)
- Yipeng Lyu, Leiden MSc student (2022)
- Shravya Shenoy, Leiden MSc student (2022)
- Yilun Ma, UCB BA student (2022)
- Katherine (Wren) Suess (UCB 2021), "The Growth & Transformation of Galaxies Across Cosmic Time"
Stanford-Santa Cruz Cosmology Fellow / UC Chancellor's Postdoctoral Fellow
- Sedona Price (UCB 2017), "Galaxies in the Young Universe: Structures, Masses, and Composition of Star-Forming Galaxies at z ∼ 1.5 − 3"
Postdoctoral Scholar at MPE
- Francesca Fornasini (UCB 2016, w/ J. Tomsick), "The Faint, the Poor, and the Steady: studies of low-luminosity, metal-poor, and non-pulsating
populations of high-mass X-ray binaries"
Assistant Professor at Stonehill College
- Jesse van de Sande (Leiden 2014, w/ M. Franx), "The Dawn of the Red and Dead: Stellar Kinematics of Massive Quiescent Galaxies out to z=2"
ARC DECRA Fellow at the University of Sydney
Other former group members:
- Guillermo Barro (UCB Postdoctoral Fellow), Assistant Professor at the University of the Pacific
- Ryan Trainor (Miller Fellow), Assistant Professor at Franklin & Marshall College
Oscar Chavez (UCB BA); Justin Clarke (UCB BA, w/ R. Feldmann); Michael Gordon (Princeton BA, w/ J. Greene);
(UCB MA); Jamie Lin (UCB BA); Meng Luo (UCB BA); Alejandro (AJ) Olvera (UCB BA); Imad Pasha
(UCB BA); Willem de Pous (visiting PhD student); Dyas Utomo
Michael Yano (UCB BA); Kevin Yu
(UCB BA); Tom Zick
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=2−3) 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
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.
2020). Over the
coming years we will apply this new approach to distant quiescent galaxies in our
Heavy Metal survey
program, to further unravel their kinematic evolution.
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) and Keck Observatory
LRIS) at higher redshifts (Kriek et al. 2016,
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
to fully exploit the use of metals for understanding the formation histories of quiescent galaxies.
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. submitted) and showed that galaxies with recently suppressed star formation
can still host large molecular gas reservoirs (Suess et al. 2017 ).
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.
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.
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).
- Introduction to Research (Astro 290), UC Berkeley
graduate class (2020)
- Introduction to Research (Astro 198), UC Berkeley
undergraduate class (2020)
- Introduction to Astrophysics, part II (Astro 7B), UC Berkeley
undergraduate class (2019-2021)
- Introduction to Astrophysics, part I (Astro 7A), UC Berkeley
undergraduate class (2013-2016)
- Galaxies (Astro 218), UC Berkeley graduate class (2012-2019)
- Math, Prison Teaching Initiative (2008-2010)
The research of my group has been funded by many agencies, including the NSF (AAG AST-1313171 and AST-1909942),
NASA (ADAP NNX14AR86G and NNX16AF54G), STScI (GO-11135, GO-12177, AR-12847, GO-15436, AR-13907, and AR-16141), Chandra (AR6-17011X),
NRAO (SOS 360180, 71847, and 72128), the Hellman Fellows fund, and the UCO mini-grant program.
Furthermore, graduate students A. Beverage, F. Fornasini, T. Jones, B. Lorenz,
S. Price and K. Suess were all supported by fellowships from the NSF-GRFP.