Witnessing the Maturing of Teenage Galaxies at z = 4 ? 6 with a Comprehensive UV - Optical - Sub-mm Benchmark Sample for the Community

With NIRSpec IFU observations of 18 representative main-sequence galaxies at z=4.4-5.7, we complete the highest-redshift kpc-resolved rest-frame UV to far-IR benchmark sample to study how the first galaxies mature and grow to become the galaxies we observe at later cosmic times. Capitalizing on more than 10 years of observations with ALMA and other observatories, and combined with the newest JWST imaging data, all 18 galaxies have (i) high (<0.2") and low (>0.5") resolution ALMA sub-mm observations providing C+ and dust continuum measurements on kpc and extended scales (ii) optical JWST/NIRCam imaging probing their optical continuum, and (iii) other ancillary data including rest-frame UV imaging and spectroscopy.

The proposed NIRSpec IFU observations add crucial spectroscopy of all main optical emission lines to this sample to constrain key properties at kpc-scales (0.1"-0.2"), including stellar masses, star-formation histories, dust attenuation, kinematics, photoionization, metallicity, and other chemical properties. With these kpc-resolution matched observations, we will jointly observe stars, gas and dust to (i) study how and where stars are formed, (ii) analyze in detail the interstellar medium, and (iii) explore and constrain the diverse dust properties and dust production mechanisms.

To-date, this is the only sample with kpc-resolution multi-wavelength photometric and spectroscopic observations from rest-frame UV to far-IR at these redshifts, hence it will have a long-lasting impact on our understanding of galaxies living in the midst of a transformational phase between primordial and mature galaxy evolution shortly after the epoch of reionization.