Universe 'Teenage Years' appear more active than expected

A survey combining Hubble, JWST and ALMA data tracked 18 early galaxies (z = 4–6) and found they accumulated heavy elements faster than expected and host numerous previously undetected active galactic nuclei.

Combining observations from Hubble, the James Webb Space Telescope and ALMA, a team led by Andreas Faisst of Caltech presented a new multiwavelength study at the American Astronomical Society meeting and published results in The Astrophysical Journal Supplement. The paper reports optical and infrared integral-field observations for 18 main-sequence galaxies at redshift z = 4–6. Researchers used different wavelength tracers to compare recent and longer-term star formation and to measure chemical abundances and nuclear activity. The study is presented as the first in a series that will examine rotation and metal gradients in these early galaxies. Key findings: - The survey covers 18 early galaxies at z = 4–6 using combined Hubble, JWST and ALMA data. - The galaxies show faster enrichment in heavy elements (metals) than previously expected, with little clear metallicity increase between the Post-Reionization epoch and the following Cosmic Noon epoch. - Many galaxies in the sample host active galactic nuclei that had not been identified earlier and are reported as actively accreting gas and dust. - Star formation in these galaxies appears "bursty," with recent H-alpha indicators differing from ultraviolet/infrared measures that probe longer timescales. - The paper is accompanied by another Astrophysical Journal article and is described as the first installment of a broader series of follow-up studies. Summary: These observations add new constraints on how rapidly early galaxies converted primordial gas into heavier elements and how common active galactic nuclei were during the Post-Reionization era. The authors present further analyses and additional papers, and future observations with a range of instruments are expected to expand this investigation.