Pascal Oesch, University of Geneva

Our Panchromatic View of Galaxy Build-up at Cosmic Dawn into the JWST Era

The first deep images with the Hubble Space Telescope (HST) have transformed our view of the Universe. Over the following more than two decades, HST continued to extend our cosmic horizon reaching to only ~400 Myr after the Big Bang at z~11. In combination with other observations across the electromagnetic spectrum, from the rest-frame optical with Spitzer/IRAC, and now all the way to (sub)mm wavelengths with ALMA/NOEMA, we are gaining a more and more complete census and understanding of galaxy build-up across 97% of cosmic history. Yet some critical gaps remain, mainly because (1) our galaxy samples are still mostly rest-UV selected at z>3, and (2) we still only have highly-incomplete spectroscopic information at z>6. In this talk, I will present an overview of our current understanding of star-forming galaxies at z>3 based on our panchromatic view from HST+Spitzer+ALMA/NOEMA data. This will be completely revolutionized over the next months, however, as the first observations with the JWST are being taken. In particular, JWST will provide deep rest-frame optical data out to z=10, both in imaging and spectroscopy, which is truly unprecedented. JWST will thus finally allow us to probe the physics of the first generations of galaxies that ended the cosmic Dark Ages and started the reionization of the Universe.