Origin of the NE low-surface-brightness feature in XMM-VID1-2075

Determine whether the low-surface-brightness feature on the northeast side of the galaxy XMM-VID1-2075 is the result of a major merger, in order to clarify the formation history and kinematic transformation of this massive quiescent galaxy at redshift z=3.449.

Background

XMM-VID1-2075 is presented as the first confirmed slow-rotating galaxy via stellar kinematics at z ≳ 2, with a measured spin parameter consistent with dispersion support and morphological evidence of asymmetries suggestive of past interactions. Its compact size and lack of significant rotation contrast with other high-redshift massive galaxies, which generally appear as fast rotators.

The paper discusses multiple potential formation pathways: a recent or ongoing major merger, the cumulative effect of numerous minor mergers, or an isotropic gas inflow that quenches star formation and suppresses rotation prior to subsequent dry mergers. The specific origin of the observed low-surface-brightness structure on the NE side remains uncertain, motivating targeted investigation to discriminate among these scenarios.