Current Research
Here are brief descriptions of the projects our students are working on. For an introductory overview, visit the Media page. For a more in-depth discussion, explore the Publications page.
Wellesley students can find research opportunities on the Wellesley Extragalactic Explorers (WEEs) page. Bangladeshi students can explore research opportunities on the Bangladesh Extragalactic Explorers (BEEs) page. If you're interested in joining our group, you’re welcome to complete the onboarding tutorial.
Star Clusters Since Cosmic Dawn
Extragalactic astronomers are on a quest to uncover how galaxies like the Milky Way were born, how they evolved, and where they are headed. While time travel isn’t possible, telescopes serve as cosmic time machines, allowing us to witness the birth of galaxies in the early universe. With JWST’s incredible sensitivity and high-resolution imaging, combined with the power of strong gravitational lensing, we can now resolve high-redshift galaxies down to their very building blocks—individual star clusters—revealing their properties and environments in stunning detail.
The discoveries from systems like the Sparkler (Mowla et al. 2023), Earendel (Welch et al. 2022), Firefly Sparkle (Mowla et al. 2024), and Cosmic Gems (Adamo et al. 2024) are already reshaping our understanding of clustered star formation in the early universe. But we’re just getting started.
In the coming year, we will analyze JWST/NIRSpec integral field spectroscopic observations of the Sparkler, conduct follow-up observations of Firefly Sparkle, and begin an ambitious new survey of 60 galaxy clusters—each containing many more sparkling galaxies, waiting to reveal their secrets. With upcoming JWST observations, we will extend our work to dozens more galaxies, pushing the boundaries of what we know about the co-evolution of star clusters and their host galaxies.
Understanding Galaxy Morphological Evolution
The study of galaxy shapes has fascinated astronomers for centuries, even before the discovery of the extragalactic universe. In the 10th century, Persian astronomer Abd al-Rahman al-Sufi recorded the Andromeda Galaxy as a "small white cloud" or nebula, distinguishing it from the stars in the night sky. Today, galaxy morphology remains a key way we classify and analyze galaxies, as their structure holds valuable clues about their formation and evolution.
One of the most fundamental properties of a galaxy is its size, which preserves a record of its assembly history. However, defining a galaxy’s size is not straightforward. A galaxy emits light from its stars and nebulae, glows at its center due to an active galactic nucleus, and interacts with dust that scatters, obscures, and re-emits radiation. Its observed structure depends on its orientation, as well as physical properties like mass, age, star formation activity, merger history, and the epoch of observation.
Measuring a galaxy's size depends on several factors, including the wavelength of observation and the specific metric used. Do we define size by the radius containing half of the light or half of the mass? What about 80% of the mass? Should we consider the 3D extent of the galaxy or its 2D projection on the sky? These choices impact how we interpret size measurements across cosmic time.
Our goal is to study how galaxy sizes have evolved from Cosmic Dawn to the present, separating observational biases from intrinsic growth. By doing so, we can better understand how galaxies assemble and evolve over billions of years.
J-HIVE
JWST observations are revolutionizing extragalactic research, revealing massive early galaxies, high-redshift AGN, and star clusters forming in the early universe. However, many studies focus on the most extreme cases—pushing the limits of redshift, mass, and uniqueness—while a vast wealth of data remains under-explored. The full potential of JWST’s extensive datasets is yet to be unlocked, particularly for understanding the typical galaxies that dominate cosmic evolution.
We are building J-HIVE: JWST's Homogeneous Information-Rich Visualization of Extragalactic Datasets, a large-scale analysis of uniformly reduced public JWST datasets (DJA). Our goals are to:
Create homogeneous catalogs of morphological (size, Sérsic indices, axis ratio) and SED-based (stellar mass, star formation rate, dust, metallicity) properties with uncertainties.
Develop an interactive web-based explorer to visualize scaling relations and individual galaxy properties.
Use machine learning to map galaxy populations based on spectral and spatial characteristics.
We are using open software for our work and our computations are being done on the Wellesley HPC. Our pipeline is available on Github. J-HIVE is designed to be accessible, lowering barriers for researchers worldwide and includes a user-friendly web interface and API, ensuring that JWST truly remains a telescope for the world.