Exploring Cosmic Dawn with James Webb Space Telescope

Project Information

FIRSTLIGHT

Grant agreement ID: 101053208

DOI

10.3030/101053208

EC signature date 8 June 2022

Start date 1 October 2023

End date 30 September 2028

Funded under

• European Research Council (ERC)

Total cost

€ 2 086 250,00

EU contribution

€ 2 086 250,00

Coordinated by

UNIVERZA V LJUBLJANI
Slovenia

Periodic Reporting for period 1 - FIRSTLIGHT (Exploring Cosmic Dawn with James Webb Space Telescope)

Reporting period: 2023-10-01 to 2026-03-31

Summary of the context and overall objectives of the project

The cosmic dark ages - when the Universe was filled with neutral hydrogen that was opaque to ultraviolet light - are thought to have ended around one billion years after the Big Bang, when the first light sources produced enough energetic photons to ionise the neutral hydrogen. This phase is referred to as the epoch of reionization and is also the era of the first galaxies' formation. However, this is also one of the least understood epochs in the Universe's evolution. When did it start/end? Was it patchy or smooth? How did galaxies reionize the Universe (if they did)? What are the properties of the earliest galaxies? This proposal will uses deep observations of the largest sample of the most powerful cosmic telescopes observed with the James Webb Space Telescope (JWST). Compared to all previous facilities, JWST’s capabilities are dazzling. Its instruments are providing data beyond those yet seen by any astronomer. The data has started to arrive and we have observed both spectroscopically and in imaging all six (and have added the seventh as a result of a successful proposal) galaxy clusters as part of the Near-Infrared Imager and Slitless Spectrograph (NIRISS) Guaranteed Time Observations (GTO) program CANUCS (CAnadian NIRISS Unbiased Cluster Survey) as well as Early Release Science program (ERS, Through the Looking GLASS). These data will allow us to (1) determine the timeline of reionization (WP1), (2) identify the exact role first galaxies played in this process by studying their ionized bubbles (WP2), and (3) determine stellar properties of the earliest galaxies (WP3).

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During this reporting period, the FIRSTLIGHT project made substantial progress toward revealing when and how the first generations of galaxies formed, how rapidly they enriched their surroundings, and how they contributed to cosmic reionization. Using new observations from the James Webb Space Telescope—including NIRCam imaging, NIRISS slitless spectroscopy, and NIRSpec spectroscopy—from the CANUCS, GLASS, as well as BULLET, PASSAGE, and BEACON surveys, we produced major advances in understanding the physical conditions of galaxies within the first few hundred million years after the Big Bang. We have published 33 papers (1 more in press) detailing these findings. They have all appeared in the top journals including Nature, Nature Communications, and Nature Astronomy.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

FIRSTLIGHT goes beyond the state of the art by:
Revealing previously unseen structures (star clusters at z ≳ 8, discovery of black holes in the early universe).
Enabling age-dating of galaxies up to z ≈ 10, a milestone in early-Universe studies.
Transforming our understanding of dust, metals, and star-formation efficiency during the first billion years.
Producing the most accurate lens models and survey calibrations available.
Providing robust constraints on ionizing-photon escape, Lyα visibility, and galaxy scarcity beyond z ≈ 9.
These achievements represent major leaps relative to pre-JWST capabilities and place FIRSTLIGHT at the forefront of early galaxy formation research.