Since light takes time to travel, the farther we look, the further back in time we see. Our group traces the story of the Universe back to its very first chapters, using JWST, ALMA, HST, VLT, Keck, and Subaru.
Chasing cosmic history: Ever since humanity first looked through a telescope a few hundred years ago, our view of the universe has rapidly expanded, and we have continued weaving a story that spans from the distant past to the present. This endeavor addresses some of the most fundamental questions (where did we come from, and where are we going?) while also seeking to answer simpler, yet profound, curiosities: what did the first light, the first stars, and the first black holes in the universe actually look like?
We trace how the first galaxies formed and grew across z > 6, combining JWST rest-frame optical spectroscopy with ALMA [CII] 158μm and dust-continuum imaging. Our group has mapped extended [CII] halos, dusty star-forming systems, and the chemical enrichment of normal galaxies in the reionization era.
Strong gravitational lensing lets us resolve early galaxies down to parsec scales and, in rare cases, individual stars. We study dense star-forming clumps inside z > 6 galaxies, candidate Pop III systems, and lensed stellar transients.
JWST and our group's multi-wavelength follow-up have revealed a diverse population of high-redshift AGN at z > 4, including the puzzling "Little Red Dots". We measure their black hole masses, accretion rates, and host galaxies to test super-Eddington growth scenarios.
Lensing clusters act as natural time-domain telescopes. We use multi-epoch JWST imaging to discover gravitationally magnified supernovae at z > 2 (and push toward z > 10), probing the high-redshift IMF and lensing time delays.
A few results we are proud of. Each card links to the paper.
JWST + ALMA resolved a z = 6.07 lensed galaxy into 15+ dense star-forming clumps, reaching <10 pc scales at cosmic dawn.
Led by PhD student Minami Nakane: a spatially-resolved galaxy just ~400 Myr after the Big Bang, found behind a VENUS lensing cluster.
A rare hybrid system at z = 7.19: a growing black hole embedded in a dusty starburst, less than 800 million years after the Big Bang.
Every paper from Seiji and the group.
"led by …" marks papers first-authored by group students and postdocs (supervised or co-supervised at the time of publication). A full PDF list is also available: Publication_Fujimoto.pdf.