Periodic Reporting for period 1 - FIRSTDUST (Far-Infrared to Radio Search for disTant Dust-obscUred galaxies and STructures)
Reporting period: 2022-07-01 to 2024-06-30
Massive dusty star-forming galaxies and galaxy protocluster contribute significantly to the cosmic star formation history in the early Universe and strongly ties to cosmology. These distant galaxies and structures trigger key questions that touch upon galaxy evolution and cosmology: How much star formation activities are obscured by dust in the early universe? How did galaxy clusters form and evolve before the cosmic noon? The FIRSTDUST project is dedicated to address these questions, aiming to 1) search for dusty star-forming galaxies out to z>6 and constrain cosmic star formation rate density; 2) discover distant galaxy groups and protoclusters at z>2 and investigate their properties to better understand their formation and evolution. To achieve these objectives, we need to produce a large galaxy catalog using deep astronomical images spanning from infrared to radio wavelengths, select distant dusty star-forming galaxies, and confirm their distant and dusty nature using spectroscopy. Meanwhile, we make use of infrared data from space telescopes and millimeter data from the advanced interferometry telescopes on the ground. This allows us to discover distant galaxy groups and protoclusters and study their star formation and interstellar mediums, shedding light on how massive galaxies and clusters form and evolve.
During the project FIRSTDUST, I produced a large galaxy catalog using a mount of astronomical data spanning from infrared to radio wavelengths. I made publications with the data from the James Webb Space Telescope, and joined the Euclid Consortium for the upcoming Euclid survey. I wrote and submitted papers to professional journals, and wrote proposals for applying telescope time. In particular, I supervised 1 master student and 2 PhD students who all published or submitted papers with me. In total, I published 4 first-author papers and 5 papers as supervisor, as well as 2 conference publications and 9 co-authored papers. For Communication, Dissemination & Outreach, I delivered 7 invited talks in conferences, colloquia and seminars; 5 contributed oral talks in international conferences; 1 public talk and 4 press releases. The publications provided state-of-the-art constraints on SFRD, reported a large number of distant galaxy protoclusters, and delivered breakthroughs that answered multiple open questions in cluster formation. These cutting-edge discoveries made me a scientist known by the community. The two years of MSCA fellowship are the most productive period in my career. The experience of supervision improved my teaching and communication skills, which trained me to be a group leader. The objectives of this project are fully achieved, and the achievements are even beyond the original plans.
The results of FIRSTDUST have strong scientific impacts in the field of galaxy and cluster formation. My publication Jin et al. 2022 unveiled a sample of compact and massive dusty star-forming galaxies at z~4 and studied their interstellar medium, which is one of the largest high-z ISM samples known to date. This study confirms the existence of a substantial population of deceivingly cold, compact dusty starburst galaxies at z>4, together with the severe impact of the CMB on their RJ observables, paving the way for the diagnostics of optically thick dust in the early Universe. My publication (as supervisor) van der Vlugt, Hodge, Jin et al. 2023 provides state-of-the-art constraints on SFRD of radio-selected dusty galaxies out to z~6. My publication Jin et al. 2024b unambiguously confirmed a z>7 candidate to be at z=2.6 cautioning against the reliability of photometric redshift of dusty objects. This work is a timely contribution to the field given the rapidly increasing availability of exquisite JWST data on dusty star-forming galaxies. My publication (as supervisor) Kokorev, Jin et al. 2023a revealed the nature of a HST-dark galaxy using ALMA and the brand-new JWST data. Our study confirms that this galaxy is an extremely dusty disk galaxy at z=2.58 with a quiescent and compact companion, providing the first insight into optically dark dusty galaxy population. On the topic of galaxy protoclusters, my publication (as supervisor) Sillassen, Jin et al. 2022 reported the discovery of a massive and compact galaxy group HPC1001 at z~3.7. Remarkably, as one of the earliest galaxy groups known to date, it shows relatively low sSFR, suggesting it could be already in a mature phase, and providing an ideal laboratory to study the formation of the earliest quiescent galaxies and cold gas accretion in dense environments. My publication Jin et al. 2023 discovered a compact galaxy group CGG-z5 at z~5.2 using the brand-new JWST data. By comparison with cosmological simulations, we found CGG-z5 is in hierarchical clustering and will collapse and form a single massive galaxy by z~2, i.e. “proto-massive galaxy”. This work provides robust observational evidence of hierarchical clustering that was only long-thought by theories. This work also demonstrates that not all galaxy overdensities will form a cluster, shedding light on the formation and evolution of massive galaxies and clusters. My publication Jin et al. 2024a reported an extreme galaxy protocluster at z=3.44 with gigantic large-scale structure, dubbed “Cosmic Vine”. Remarkably, we identified multiple massive quiescent galaxies in this structure, which is totally unexpected in current cluster formation models. The results unambiguously reveal that massive quiescent galaxies can form in growing large-scale structures at z>3, and disfavoring the environmental quenching mechanisms that require a virialized cluster core. This work thus challenged current models and answered multiple questions in cluster formation, which are breakthroughs in the field. My publication (as supervisor) Sillassen, Jin et al. 2024 identified a sample of eight massive groups at 1.6