2022 NHFP Fellows

Host Institution: Massachusetts Institute of Technology

Proposal Title: The Awakening of Massive Black Holes

Riccardo Arcodia was born and raised in Italy. He took both his Bachelor's degree in Physics, and Master's degree in Astrophysics and Space Physics, at the University of Milan-Bicocca (Milan, Italy), carrying out research projects at the nearby Observatory of Brera-Merate. He then moved to Germany to pursue his PhD in Physics and Astronomy at the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, under the supervision of Prof. Kirpal Nandra and Dr. Andrea Merloni. Since graduating in 2021, Riccardo has been a postdoctoral researcher in the High Energy Astrophysics group at MPE.

Riccardo's research focuses on studying accretion onto black holes of different masses, from X-ray and optically bright active supermassive black holes to stellar-mass black holes. He also significantly contributed to the discovery and study of a new rare outlier in the family of massive accreting black holes in the nuclei of galaxies, the so-called quasi-periodic eruptions. As an Einstein fellow at Massachusetts Institute of Technology, Riccardo will continue his search for more of these fascinating objects (of which only a handful is known to date) with the eROSITA X-ray telescope and he will be at the forefront of efforts to study their X-ray and multi-wavelength properties, in an attempt to unveil more about their origin.

Host Institution: University of Chicago   

Proposal Title: Line Intensity Mapping with mm-wave Spectrometers: Targeting a New Cosmological Observable

Jessica Avva Zebrowski grew up near Atlanta, Georgia. She received an undergraduate degree in physics from the University of Chicago. Since then, she has been a graduate student at the University of California, Berkeley, and will graduate with a PhD in physics in the summer of 2022.  Jessica's research centers on understanding cosmic acceleration. In graduate school, she focused on probing inflation by mapping the oldest light in the universe with Cosmic Microwave Background (CMB) experiments. This work involved improving instrumental noise performance and developing novel data analysis techniques to optimize the inflationary constraints of the South Pole Telescope on large angular scales. 

As an Einstein Fellow, Jessica will bring her expertise in mm-wave instrumentation and data analysis to the University of Chicago to build experiments that can pioneer the technique of Line Intensity Mapping. These experiments will constrain cosmology by mapping the evolution of Large-Scale Structure over time. This will fill in the gap in cosmic history between the CMB and near-time optical measurements and lead to new constraints on dark energy, inflation, and beyond.

Host Institution: Michigan State University

Proposal Title: Combining Observations with Simulations to Decipher Shocks in Novae

Elias Aydi was born and raised in El-Mina, Lebanon. He received his Bachelor's in Physics from the Lebanese University in 2011, and graduated with a Masters in Astrophysics from Notre Dame University and Saint Joseph University (Beirut) in 2014. Then he graduated with a PhD in Astronomy from the South African Astronomical Observatory and the University of Cape Town in 2018. During his PhD, he carried out multi-wavelength studies of nova eruptions and 3D radiation-hydro modeling of evolved stars. After receiving his PhD, Elias joined Michigan State University as a postdoctoral research associate, working on exploring the role of shocks in powering nova eruptions.

In the past decade NASA's Fermi gamma-ray satellite has established novae as a new class of high-energy gamma-ray sources, which led to a paradigm shift in our understanding of these eruptions, with implications to other cosmic explosive phenomena. The high-energy gamma-ray emission from novae highlighted the role of strong shocks, the product of collision between ejected material during the explosion, in powering the emission in novae. Recently, Aydi led a study that combined observations from several NASA missions, which provided the first direct observational evidence that shocks could indeed power a large fraction of the luminosity of a stellar explosion, possibly surmounting the emission powered by the thermonuclear reactions. As a Hubble Fellow, Elias will combine multi-wavelength observations from a diversity of NASA's space-based facilities and several ground-based observatories, along with 3D radiation-hydro simulations to decipher shocks in novae, and work on solving several long-standing puzzles in high-energy astrophysics.

Host Institution: Columbia University

Proposal Title: Testing Galaxy Formation Models with Large-Scale Surveys of the Milky Way Stellar Halo

Emily Cunningham grew up in Brooklyn, New York. She received her Bachelor's degree in Physics & Astronomy from Haverford College in 2012. She then spent a year at the Institut d'Astrophysique de Paris, funded by the Fulbright U.S. Student Program. Emily completed her PhD in Astronomy & Astrophysics at UC Santa Cruz in 2019, working with Alis Deason, Raja Guhathakurta and Connie Rockosi. Since September 2019, Emily has been a Flatiron Research Fellow at the Center for Computational Astrophysics, collaborating in the Dynamics and Astronomical Data groups.

Emily's research focuses on the Milky Way (MW) stellar halo, with a particular interest in using simulations to develop novel methods for analyzing and interpreting chemical and kinematic observations of halo stars. According to the hierarchical paradigm for galaxy evolution, the MW built up its halo of dark matter over cosmic time by accreting smaller dwarf galaxies. The remnants of these accreted dwarfs make up the MW's stellar halo. Halo stars can therefore be used both to constrain the dark matter distribution of the MW as well as inform us about the dwarf galaxies in which they formed. As a Hubble Fellow at Columbia, Emily will continue to use new and upcoming large-scale surveys of the Milky Way stellar halo, in conjunction with state-of-the-art simulations and statistical methods, to address fundamental questions in galaxy formation.

Host Institution: California Institute of Technology

Proposal Title: Probing Planet Formation with the Most Extreme Cases

Fei grew up in Nanjing, China. He received his bachelor's and master's degrees in Natural Science from the University of Cambridge in 2014. Fei obtained his PhD in Physics from MIT under the supervision of Prof. Josh Winn. He is currently a postdoctoral fellow in the Division of Geological and Planetary Sciences at the California Institute of Technology and will remain at Caltech as a NASA Sagan Fellow.

Using both novel data analysis techniques and numerical simulations, Fei strives to understand the most unexpected outcomes of planet formation, such as the "ultra-short-periods," the "super-puffs," and oblique planets. The mere existence of these planets is puzzling; however, they provide a unique opportunity to study critical processes in planet formation and evolution that may be too weak or too slow to be observable on other planets. As a Sagan Fellow at Caltech, Fei will leverage the upcoming Keck Planet Finder to better characterize the most extreme planetary systems, and shed light on planetary composition, mass loss, and orbital architecture.

Host Institution: Northwestern University

Proposal Title: Illuminating the Progenitors and Environments of Energetic Transients with Radio Observations

Tarraneh's research focuses on the study of astrophysical transients, ranging from rare classes of supernovae to fast radio bursts (FRBs), luminous bursts lasting only milliseconds and originating from extragalactic distances. Her work leverages radio and millimeter observations of these energetic events to shed light on the properties of their progenitors, outflows, and environments. She has also made several key predictions for millimeter transient discovery in next-generation Cosmic Microwave Background surveys. 

As an Einstein Fellow and a member of the Fast and Fortunate for FRB Follow-up collaboration, Tarraneh aims to elucidate the origin of FRBs and to fill a critical gap in the duration-luminosity phase space for radio transients. In particular, she will leverage radio and X-ray observations of well-localized FRBs to constrain FRB-progenitor models and to probe the presence of active galactic nuclei in FRB host galaxies, with implications for the stellar populations that should ultimately drive FRB production. She will also conduct the first systematic search for late-time radio emission from a large sample of supernovae in the nearby universe, lending to detailed studies of the mass-loss histories of the progenitors on timescales of centuries prior to their explosion, and hence the densities of the circumstellar medium on some of the largest physical scales studied to date. Her work will therefore make important strides towards our understanding of FRB progenitors, as well as the final stages of the evolution of massive stars.

Host Institution: University of Texas, Austin

Proposal Title: Decoding a Rosetta Stone for Galaxies at the Epoch of Reionization with JWST and ALMA

Seiji Fujimoto grew up in Kyoto, Japan. He received bachelor's (2014) and master's degrees (2016), and PhD (2019) in astronomy from the University of Tokyo. He is currently an independent postdoctoral researcher based at the Cosmic DAWN Center in Denmark with the dual titles of DAWN Fellow and INTERACTIONS Fellow.

Seiji is interested in the formation and evolution of galaxies and black holes in the early universe. To link visible and dust-obscured sides of these fascinating systems, he developed an expertise in observational techniques combing the electromagnetic spectrum from optical to radio wavelengths. Over the next several years at the University of Texas, Seiji will apply these techniques to his multiple Principal Investigator programs of JWST and ALMA, characterizing three fundamental aspects of the early galaxies: their metal enrichment, the assembly history of their stellar dust, gas, dark matter, and kinematics. Seiji will also apply the same approach to other JWST treasury programs in collaborations to search for the first emergence of stellar light and dust in the universe and to investigate the primary formation and evolution mechanisms from the first galaxies in the first billion years after the Big Bang.

Host Institution: Harvard University

Proposal Title: The Role of Physical Processes and the Environment in Star Formation

Dávid Guszejnov is from Budapest, Hungary. He obtained his BSc and MSc in physics from the Budapest University of Technology and Economics, where he also had his first research experience in the field of fusion plasma physics. He went on to do his PhD at the California Institute of Technology, where he pursued research in astrophysics and wrote his dissertation "On the Origin of Scales and Scaling Laws in Star Formation" with Prof. Philip Hopkins. After graduating, he became a Harlan J. Smith Fellow at the University of Texas at Austin.

Dávid's research primarily focuses on the rich phenomena of star formation and their broader implications. He uses both analytical and numerical tools to answer questions like: What regulates star formation? What sets the characteristic mass of stars? Why are stars clustered? How is star formation different in other galaxies?

Host Institution: New York University

Proposal Title: Illuminating the Primeval Universe with Lyman-alpha

Sultan Hassan is from Sudan. He was born and grew up in Saudi Arabia. He received his B.Sc. in Physics from the University of Khartoum, Sudan in 2009. He then moved to South Africa to pursue a career in Astronomy, obtaining his Honours and M.Sc. in Astrophysics & Space Science from the University of Cape Town, South Africa from 2011 to 2013. During his PhD studies, he was a visiting fellow at the Max Planck Institute for Astrophysics in 2017. Sultan then earned his PhD in Physics from the University of the Western Cape, South Africa in 2018. Afterwards, he was an SKA Postdoctoral Fellow at the University of Western Cape in 2018, and a Tombaugh Postdoctoral Fellow at New Mexico State University from 2018 to 2020.  Currently, Sultan is a Flatiron Research Fellow at the Flatiron Institute's Center for Computational Astrophysics since September 2020.

Sultan's research focuses on developing more accurate physically motivated sub-grid models of ionizing sources to unravel the nature of reionization on small and large scales. He is interested in developing efficient tools that are capable of extracting the maximum amount of information from current and future reionization surveys, using a wide range of techniques including semi-analytical/semi-numerical models, radiative transfer hydrodynamics simulations with machine learning, and Bayesian inference. 

As a Hubble fellow, Sultan will develop a fast and accurate Lyα sub-grid model that accurately follows the journey of Lyα photons from the interstellar medium through the circumgalactic medium, and up to the intergalactic medium scales, hence providing the most accurate interpretations/forecasting of future Lyα surveys by Webb, SPHEREx, and Roman.

Host Institution: Columbia University

Proposal Title: Constraints on Galaxy Evolution Using Star-Formation Histories

Kartheik Iyer grew up in Mumbai, India and earned his undergraduate degrees in Physics and Computer Science from Birla Institute of Technology and Science, Pilani – Hyderabad campus. He moved to the US to pursue his PhD in Physics and Astronomy at Rutgers University, where he worked with Prof. Eric Gawiser on developing the Dense Basis method for reconstructing the star-formation histories (SFHs) of distant galaxies. He is currently a Dunlap Postdoctoral Fellow at the Dunlap Institute for Astronomy and Astrophysics at the University of Toronto.

Kartheik's research interests lie in characterizing and measuring the timescales on which physical processes like gas inflows, feedback, and baryon cycling influence galaxy evolution. On the observational side, he builds public tools to infer the physical properties of distant galaxies using noisy spectrophotometric measurements from ground- and space-based telescopes, applying them to large surveys.

As an NHFP Hubble Fellow at Columbia University, Kartheik will advance our current understanding of galaxy evolution using observations from major NASA observatories including Hubble, Webb, and Roman to make the most accurate measurements of galaxy SFHs to date. In conjunction, he is developing models for the relation between star-formation rate stochasticity at different timescales and the physical processes driving them. Analyzing observationally reconstructed SFHs in conjunction with those from cosmological simulations in the framework of this model will allow us to make testable predictions for the strength of feedback and baryon cycling in driving galaxy growth and quenching across a range of cosmic epochs. 

Host Institution: University of California, Berkeley

Proposal Title: Unveiling the Hidden Population of Black Holes in our Galaxy

Tharindu Jayasinghe was born and raised in Colombo, Sri Lanka. He obtained his Bachelor's degree in Physics from the California State Polytechnic University, Pomona in 2017. He then went on to graduate school at the Ohio State University in Columbus, Ohio. He will finish his PhD under the supervision of Professors Krzysztof Z. Stanek, Christopher S. Kochanek, and Todd A. Thompson in summer 2022. Tharindu is an observational astronomer and a member of the All-Sky Automated Survey for SuperNovae (ASAS-SN).

Tharindu's research focuses on using time-domain surveys and multi-wavelength follow-up to characterize variable stars and non-interacting compact object–stellar binaries in the Milky Way. For his thesis, he systematically characterized the variability of over 60 million bright stars using data from the ASAS-SN survey. He led the development of a variability classification pipeline using machine-learning techniques, leading to the first all-sky catalog of homogeneously identified and classified bright variable stars, totaling 660,000 variables and including 220,000 new discoveries. Tharindu also leads the ongoing citizen-science project "Citizen ASAS-SN" and has worked as the technical lead for the "Milky Way Project" on the Zooniverse. He also searches for non-interacting compact-object-stellar binaries in the Milky Way, and has led the discovery and characterization of several candidates.

As an NHFP Hubble fellow at the University of California, Berkeley, Tharindu plans to use all-sky photometric and spectroscopic surveys, along with multi-wavelength follow-up data from both ground- and space-based observatories, to discover and characterize non-interacting compact object–stellar binaries. By discovering these systems, his goal is to uncover the hidden population of non-interacting compact objects and to study their mass distribution in the Milky Way.

Host Institution: California Institute of Technology

Proposal Title: Modeling Black Hole Dynamics in Dense Star Clusters

Kyle Kremer grew up in Kettering, Ohio. He received his bachelor's degree in 2012 from Northwestern University with a double major in physics and music performance. Following his undergraduate studies, Kyle spent three years pursuing a career as an orchestral musician (earning a master of music degree at the Colburn School in Los Angeles in 2015) before ultimately returning to Northwestern where he earned his PhD in astronomy in 2019, advised by Fred Rasio. Following his PhD, Kyle moved back to southern California as an NSF Astronomy & Astrophysics Postdoctoral Fellow at Caltech and Carnegie Observatories.

Over the past few years, the groundbreaking detections of gravitational-wave signals from merging binary black holes and neutron stars by LIGO/Virgo have opened a new window to the cosmos. A key question regarding these gravitational-wave sources is the nature of their origin. Dynamical formation in dense environments like globular clusters has emerged as an important formation channel, corroborated by numerical simulations and observational indications suggesting globular clusters contain dynamically significant populations of black holes throughout their lifetimes. As an NHFP Einstein Fellow, Kyle will use dense stellar clusters as laboratories to study gravitational-wave sources and electromagnetic transients, leveraging these parallel fields to pursue three key themes: (1) Exploration of the formation and evolution of massive black holes in dense star clusters; (2) Hydrodynamic modeling of collisions and tidal-disruption events in clusters and study of the associated electromagnetic transient signals; and (3) Modeling of young super star clusters in connection with forthcoming observations by Webb.

Host Institution: University of Texas, Austin

Proposal Title: The Role of Dark Matter in Growing and Quenching the First Massive Galaxies

Arianna Long was born in Maryland and spent her childhood split between the Florida Keys and Montgomery County, Maryland. She achieved her Bachelor's of Science in Applied Mathematics from Towson University, Maryland with a minor in education and in computer science. After some time as a data analyst in the consulting industry, Arianna returned to higher education to achieve her Master's in Physics as part of the inaugural cohort of the Cal State University, Los Angeles's NASA Data Intensive Research and Education Center for STEM (DIRECT-STEM) program. She then pursued her doctoral degree in physics and astronomy as a Eugene Cota Robles Fellow and Ford Foundation Fellow at the University of California, Irvine. In addition to her research, Arianna is a mentor and leader, having founded and led several mentoring programs to support marginalized scientists such as PACE@UCI, the League of Underrepresented Minorities in Astronomy, and the Guerrilla Mentoring initiative at #VanguardSTEM.

Arianna's research aims to understand how massive galaxies form, grow, and die in the high-redshift universe. In her thesis work, she uses multi-wavelength observations and numerical modeling to tease out links between dusty, star-forming galaxies in the early cosmos and their fated quiescent descendants at later times. As a Hubble Fellow at University of Texas, Austin, Arianna will use incoming data from state-of-the-art telescopes like Webb and ALMA to study the gas, stellar, and dark matter content of thousands of massive galaxies in the early cosmos. She will explore connections between dark-matter halo growth, gas accretion and depletion, and stellar assembly in these galaxies to test several evolutionary theories, and determine how these galaxies transition from hyper-efficient, gas-rich star formers, to giant, red-and-dead stellar graveyards—all within the first few billion years of the cosmos.

Host Institution: University of Arizona

Proposal Title: Disk Substructures and the Act of Planet Formation

Feng Long was born and grew up in the southwest mountain area of China. After receiving her bachelor's degree in astronomy from Peking University in 2013, she stayed there and completed her PhD in 2019. She then moved to the US and has since been an SMA (Submillimeter Array) Postdoctoral Fellow at the Center for Astrophysics | Harvard & Smithsonian. 

Feng's research focuses on the formation and evolution of protoplanetary disks—the cradle of young planets. In particular, she uses the powerful radio interferometers to study the physical and chemical properties of protoplanetary disks, and thereby to identify key aspects of the planet-formation process. Her past works have demonstrated the prevalence of gap and ring features in disks, which are the likely imprints of young planets. As a Sagan Fellow at the University of Arizona, Feng will employ observational data from cutting-edge facilities to establish the impact of these disk features on planet formation and to study the associated young planet population. She aims at better understanding the earliest phase of planet formation, and to shed light on the origin of the observed diversity in exoplanet properties. 

Host Institution: University of Michigan

Proposal Title: A Multidimensional Approach to Exploring Disequilibrium Chemistry in Exoplanet Atmospheres

Ryan MacDonald was born and grew up in Derby, England. Ryan received a Master's degree in Physics from Oxford University in 2015 and a PhD in Astronomy from Cambridge University in 2019. He then crossed the pond to the United States, where he is currently a Postdoctoral Research Associate at Cornell University's Carl Sagan Institute. Alongside his research, Ryan produces educational videos on YouTube about space exploration, seen by over 5 million people from 165 countries.

Ryan's research spans the boundary between theoretical and observational studies of exoplanet atmospheres. He has developed cutting-edge techniques to measure exoplanets' chemical composition, cloud properties, and temperature structure from spectroscopic observations of their atmospheres. Ryan's interests cover the full diversity of strange and exotic worlds beyond our solar system, ranging from inferno, ultra-hot Jupiters to temperate rocky planets in the habitable zone.

As a Sagan Fellow at the University of Michigan, Ryan will be using the James Webb Space Telescope to uncover signatures of disequilibrium chemistry across a population of exoplanets. Ryan's research will ultimately inform the search for one of the most profound sources of disequilibrium chemistry: life in the Universe.

Host Institution: University of Chicago

Proposal Title: Precision Cosmological Modelling in Nonlinear General Relativity

Hayley grew up in Melbourne, Australia, where she completed her undergraduate studies in astrophysics at Monash University. She received her PhD in 2019, also from Monash, supervised by Daniel Price and Paul Lasky. Since then, she has been a Herchel Smith fellow in the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge.

Hayley is interested in learning about the effects of nonlinear general relativity in cosmology. During her PhD, she led one of the first groups to use numerical relativity for cosmological simulations of large-scale structure formation. Usually, cosmological simulations and analysis of observations involve simplifying assumptions such as Newtonian dynamics or a homogeneous and isotropic spacetime expansion. While these assumptions have been invaluable in building modern cosmology, some disagreements between theory and observation are coming to light as our data gets more precise. Additionally, some aspects of the standard cosmological model remain physically unexplained. As an Einstein fellow, Hayley will study cosmological observables in a numerical framework which is free from common simplifying assumptions. Hayley hopes to find out whether using nonlinear general relativity in our cosmological modelling can help improve our understanding of the universe.

Host Institution: Massachusetts Institute of Technology

Proposal Title: The First Glimpse of the First Galaxies: A Near & Far Approach

Rohan Naidu grew up in Hyderabad, India. In a Bollywood-esque plot twist, at age 18 he dropped out of engineering school, bought his first-ever plane ticket, and joined the founding class of 150 students at Yale-NUS College, Singapore, one of Asia's first liberal arts colleges. He will soon earn his PhD in Astronomy at Harvard University as part of Prof. Charlie Conroy's research group, and as a core member of the H3 Survey.

Rohan's research focuses on the first galaxies that formed after the Big Bang. His work addresses when these galaxies emerged to illuminate the universe, how they ionized the intergalactic reservoirs of hydrogen, and how they synthesized the elements that would one day seed life on Earth. As a Hubble Fellow, Rohan will pursue these galaxies with a near-and-far approach. As one of the first users of NASA's James Webb Space Telescope, he will lead direct observations of galaxies at the highest redshifts. And through archaeological studies of our own galaxy, aided by ESA's Gaia satellite, Rohan will excavate and characterize ancient, immigrant galaxies that lie buried within the Milky Way.

Host Institution: Harvard University

Proposal Title: Red Supergiant Binaries on the Path to Becoming Gravitational Wave Events

Kathryn Neugent graduated from Wellesley College in 2010 with a double degree in Computer Science and Astronomy. She then worked for several years in cyber security and obtained her M.S. in Computer Science from George Washington University in 2012. Kathryn continued to do astronomical research in her spare time, and after a few years decided to pursue it as her career. In 2017, Kathryn obtained her M.S. in Applied Physics from Northern Arizona University, where she discovered and characterized a unique type of Wolf-Rayet star. For her PhD dissertation at the University of Washington with Dr. Emily Levesque, Kathryn determined the red supergiant binary fraction throughout the Local Group galaxies, and graduated in 2021. Throughout all these years, she additionally worked as a research associate at Lowell Observatory with Dr. Phil Massey after doing a summer Research Experience for Undergraduates at Lowell in 2009. Kathryn is currently a Dunlap Postdoctoral Fellow at the University of Toronto. She will soon start as a NHFP Hubble Fellow at Harvard University and will additionally stay at Harvard | SAO as a Center for Astrophysics Fellow after she finishes the Hubble Fellowship.

Kathryn's research focuses on studying massive stars across the HR Diagram from hot OB and Wolf-Rayet stars, to cool yellow and red supergiants, and she regularly travels to telescopes in Chile, Hawaii, and Arizona to better constrain the numbers and types of these stars in the Local Group galaxies M31, M33, and the Magellanic Clouds. Her recent research focuses on using these massive stars in binary systems to determine how they might someday merge to form gravitational wave events detectable by the Laser Interferometer Gravitational-wave Observatory. In her free time, Kathryn enjoys hiking, knitting, and spending time with her animals.

Host Institution: University of Hawaii Institute for Astronomy

Proposal Title: Constraining Post-main-sequence Angular Momentum Evolution with Mixed-mode Asteroseismology

Joel Ong was born and raised in Singapore. He received his bachelor's degree in 2016 from the National University of Singapore, where he majored in Physics. Joel is currently a graduate student at Yale University, where he works with Prof. Sarbani Basu; he will receive his PhD in August 2022.

Joel's research centers on mixed-mode asteroseismology—stellar pulsations of combined acoustic and buoyant character—and its use in constraining the structure, evolution, and properties of evolved giant stars. The analysis and interpretation of these pulsations has relied on concepts inherited from the study of the Sun, which behaves very differently. For his PhD, Joel developed new techniques to better describe how waves propagate in these giant stars in particular, and used these new methods to study populations of stars observed with the Transiting Exoplanet Survey Satellite (TESS).

Over the course of the coming decade, we expect a deluge of asteroseismic space measurements, both from existing space observatories like TESS, as well as new ones like PLATO (Planetary Transits and Oscillations of Stars). Much of their data will be from giant stars, whose bright and slow pulsations are easiest to measure. As a Hubble Fellow at the University of Hawaii, Joel hopes to explore the way in which these stars redistribute angular momentum within their interiors over the course of their rapid expansion, among other applications of mixed-mode measurements.

Host Institution: Institute for Advanced Study

Proposal Title: Multiwavelength Flares in the High-energy Universe

Bart Ripperda grew up in Kerkrade, the Netherlands. He received his master's degree in plasma physics from Eindhoven University of Technology in 2013. He then moved to the University of Cambridge for part III of the mathematical tripos, before starting his PhD in mathematics at Katholieke Universiteit (KU) Leuven in Belgium in 2014. After his PhD, he joined the Event Horizon Telescope in 2018 and spent a year as a Humboldt Fellow at Goethe University in Frankfurt, Germany. In 2019, he became a joint postdoctoral fellow at the Flatiron Institute in New York City and at Princeton University.

Bart is a theoretical astrophysicist trying to connect fundamental plasma physics with observations of high-energy emission from black holes and neutron stars. His research centers around large-scale numerical simulations of plasma dynamics in the vicinity of compact objects.

Black hole accretion disks and their jets consist of magnetized, collisionless, relativistic plasma. They produce high-energy radiation in the form of short, intense flares. Modeling these systems necessitates a deep understanding of the kinetic plasma dynamics that is responsible for energy dissipation and particle acceleration. As an Einstein Fellow, Bart aims to study flaring and high-energy emission signatures from regions close to black hole event horizons. By using a novel combination of first-principles general-relativistic kinetic simulations and large-scale magnetohydrodynamics models he aims at capturing microscopic plasma physics and global dynamics. His work investigates how very-high-energy flares are powered nearby the event horizon of active galactic nuclei like M87 and whether similar mechanisms can power X-ray/infrared flares from Sagittarius A* in our own galaxy. His simulations will provide quantitative comparisons with prime targets for various NASA missions such as Fermi, Chandra, Spitzer, NuSTAR, and the James Webb Space Telescope.

Host Institution: Princeton University

Proposal Title: The Diversity and Orbital Architectures of Planets Orbiting Cool Stars

Guðmundur Stefánsson grew up in Kópavogur, Iceland. He received his BSc in Physics from the University of Iceland in 2013. Guðmundur went on to graduate school in Astronomy & Astrophysics at the Pennsylvania State University, where he was awarded a Fulbright Fellowship, Leifur Eiríksson Fellowship, and a NASA Earth and Space Science Fellowship. Guðmundur's PhD dissertation "Extreme Precision Photometry and Radial Velocimetry from the Ground," completed in 2019 under the guidance of Prof. Suvrath Mahadevan, was recognized by the Robert J. Trumpler award for a PhD thesis deemed unusually important to astronomy. Since completing his PhD, Guðmundur has been a Henry Norris Russell Fellow at Princeton University.

Guðmundur's research combines experimental and observational astrophysics to better detect and characterize small planets orbiting nearby low-mass stars. Low-mass stars are the most numerous stars in the galaxy and the most nearby stars to the Sun. However, planets orbiting low-mass stars have remained relatively poorly studied due to their faintness at optical wavelengths.

As a NASA Sagan fellow at Princeton University, Guðmundur will leverage his expertise and access to next generation high-resolution spectrographs operating at red-optical and near-infrared wavelengths to gain further insights into the diversity of planets orbiting nearby low-mass stars. Guðmundur will lead the Habitable-zone Planet Finder survey to detect and characterize planets around ultra-cool stars which are some of the best targets for detecting planets in the habitable zone and planets that could exhibit star–planet magnetic interactions at radio wavelengths. Additionally, Guðmundur will use in-transit spectroscopic observations to investigate connections between orbital architectures and atmospheres of small planets.

Host Institution: Carnegie Observatories

Proposal Title: Mapping the Signatures of Shock Breakout

David Vartanyan was born in Glendale, CA to Armenian immigrant parents. He received his Bachelor of Science in Astrophysics from Caltech and a PhD in Astrophysics from Princeton advised by Professor Adam Burrows.

David is currently a Theoretical Astrophysics Fellow at University of California, Berkeley. His interests span the gamut of core-collapse supernovae theory as enabled by high-performance computing, from the dependence of progenitor structure and detailed microphysics on the ultimate fate of massive stars, to the neutrino and gravitational wave signatures sourced by these explosive phenomena. His work has been at the forefront of supernova theory and has transformed the paradigm of the last decades—where supernovae simulations would fail to explode—to the current era, where detailed models yield robust explosions. He was awarded the NERSC Early Career Award for High Impact Scientific Achievement for these developments. 

As an NHFP Einstein Fellow, David will pioneer state-of-the-art shock-breakout simulations of supernovae to weave theoretical understanding together within an observational framework. This effort will allow the mapping of late-stage stellar evolution to space- and time-domain observations of supernovae remnants to explore their nucleosynthetic chemistry, which seeds the building blocks of organic life. David's personal interests include gardening and air guitar techniques. 

Host Institution: Carnegie Earth and Planets Laboratory

Proposal Title: Assessing the Network Topologies of Planetary Atmospheres for Potential Biosignatures

Michael L. Wong grew up in California gazing at the stars, wondering who might be out there gazing back at him. Upon entering University of California, Berkeley, he was dismayed that he couldn't find any classes on astrobiology, so he pursued a bachelor's degree in planetary science, reasoning: "If I can't study aliens, I might as well study where aliens might live." Mike followed this passion down the I-5 to Caltech, where he earned his master's and doctorate in planetary science. After graduation, he drove the I-5 in the opposite direction to become a postdoc at the University of Washington (UW) where, finally, he'd made it to a degree-granting program in astrobiology—except he had run out of degrees to get. So, Mike crossed to the other side of the classroom and invented his own astrobiology class for undergraduate STEM majors at UW, giving the next generation of stargazers an opportunity he never had: a whole course dedicated to the possibility of life in the universe.

Teaching astrobiology is incredibly exciting because it is a constantly evolving field—a field that Mike is passionate about shaping through his research. Mike uses numerical models to answer questions about planetary habitability, the emergence of life, and the search for biosignatures. He has expertise in photochemistry and is especially interested in how atmospheric chemistry can promote and reflect the presence of a biosphere. In his past work, he has investigated the production of organics in the atmospheres of Titan and Pluto, nitrogen fixation on early Earth and early Mars, and the photochemical cycles of Venus-like exoplanets. As a Sagan Fellow at the Carnegie Institution for Science's Earth & Planets Laboratory, Mike will apply the tools of network science to characterizing planetary atmospheres with the goal of developing new ways of looking for life elsewhere. He believes that there are a lot of hidden gems waiting to be found—hidden truths about life that can be revealed through abstract approaches—that will help us search for extraterrestrial life, especially life that we have yet to even imagine. Mike will also continue to think critically about the origins of life and the development of a universal theory of life, questions that are intimately intertwined with the science of biosignatures. Although he will not have teaching responsibilities as a Sagan Fellow, Mike will keep on sharing science with the public through Strange New Worlds: A Science & Star Trek Podcast.

Host Institution: University of California, Santa Cruz

Proposal Title: Probing the Formation of Directly Imaged Exoplanets via Robust Atmospheric Characterization

Zhoujian ("ZJ") Zhang grew up in Shandong, China. He received his bachelor's degree in Astronomy from Nanjing University in 2015. He then moved to the University of Hawaii and earned his PhD degree in Astronomy in 2021. He is currently a postdoctoral fellow at the University of Texas at Austin.

ZJ's research focuses on the atmospheres, formation, and evolution of exoplanets and brown dwarfs. He has led a large volume-limited survey of long-period giant planets and brown dwarfs that are orbiting nearby stars. He has used his discoveries to study the atmospheres and demographics of planetary-mass and substellar objects. ZJ has also investigated the atmospheric escape of short-period irradiated exoplanets, as well as the orbital architecture of planetary systems. As a Sagan Fellow, ZJ will further expand the census of imaged planets by mining the existing and upcoming wide-field sky surveys. Also, he will carry out a large program to uniformly characterize the physical properties for the growing census of directly imaged planets and long-period brown dwarfs, as well as their host stars, in order to reliably probe planet formation.