A panchromatic view of galaxy build-up in the first 2 Gyrs of cosmic history

Over the past decades, several important steps have been taken to understand the formation and evolution of first generations of galaxies. Thanks to deep multi-wavelength observations by Hubble Space Telescope (HST), studies of early galaxies have now been pushed well into the Epoch of Reionization, i.e. up to z~10-11 only 500Myr after the Big Bang (e.g. Bouwens+15, Oesch+16, Atek+18). However, our current knowledge beyond z~2-3 is significantly biased to the rest-frame ultraviolet observations as it's only accessible by deep optical/near-infrared observations, and dust-obscured properties of high-redshift galaxies has remained mostly unknown. This situation was revolutionized by extremely sensitive and high-resolution far-infrared (FIR) interferometers such as ALMA and NOEMA. First ALMA observations showed us surprises by finding fainter FIR emission and potential fainter [CII] 158um emission than expected from low-redshift galaxy observations, suggesting an evolution of dust-obscured properties and interstellar medium (ISM) properties of galaxies at high-redshift (e.g. Capak+15, Bouwens+16, Matthee+19, Harikane+20). To understand these potential evolutions with statistical sample and with wide ranges of galaxy parameters, large ALMA observations were required. In this talk, I introduce results obtained from one of the recent ALMA large program: ALPINE, and discuss the evolution of dust attenuation properties and its impact on the interpretations of [CII] 158um emission observations. The studies of dust attenuation properties and ISM properties are crucial to interpret existing and upcoming observations, including upcoming very high-redshift galaxy observations by ALMA and JWST.