“These galaxies are the most luminous and intense star-forming galaxies in the Universe. They are even identified as maximal starbursts”

Evolutionary scenario: interaction/mergers -> very intense and short starburst-> blowout phase of ISM->compact quiescent galaxy. They show a large variety of morphologies (members of protoclusters, major or minor mergers, large SF disks), but the triggering mechanisms of starburst is unclear. Due to their extreme faintness at (rest-frame) optical wavelengths, the stellar structure of extreme starbursts is mostly unknown, out of reach from HST, while Spitzer lacks angular resolution.
With JWST study the stellar mass distribution. East-lensed (E) and a West-lensed (W) galaxy are separated by a projected distance of 8 kpc, relative velocities of 700 km s−1, extremely luminous in the IR, extreme sSFR

Clumps in gas rich system fed by cosmological cold streams, unstable -> clump form -> clumps will migrate inwards in ~2 orbital periods to form a spheroidal galaxy. Bulge growth and feeding BH -> bright AGN

Or clumps produced by mergers. The two galaxies are likely interacting.