Mergers represent one of the most critical phases in galaxy evolution, driving morphological transformations and rapid mass build-up at cosmic noon, when galaxies assemble their mass most efficiently. To gain critical insight over these processes, we have used high-resolution ALMA and JWST observations of a major-merger-induced double starburst at z=1.525, resolving scales down to 300 pc. The system reveals diverse structures, including highly obscured starbursting cores, unobscured tidal tails, clumps, tentative molecular outflows, and potential progenitors of stellar halos. VLA data also show radio jets 20 kpc away from the pair, yet we find little evidence for significant AGN impact on their star formation. This multi-wavelength analysis captures the consequences of the first passage of a massive merger: nuclear starbursts efficiently build bulges within gas-rich disks that remain largely intact; tidal tails host newly formed stars, while stripped older stars form a more diffuse component; and AGN activity, possibly triggered by the interaction, may represent a brief episode but can exert long-term influence by heating the halo and suppressing cold gas accretion, potentially leading to quenching. This study extends the legacy of Arp 220 into cosmic noon, revealing how massive galaxies formed their bulges and regulated their growth.
