Displacement and rotation of the ID6 molecular gas reservoir

Determine whether the molecular gas reservoir in the ID6 merger system can be displaced by several kiloparsecs while retaining evidence of coherent rotation, and thereby constrain whether tidal interactions or ram-pressure stripping produced its observed offset.

Background

The ID6 system consists of two merging galaxies whose CO(3–2) and dust emission are offset by approximately 2.5 kpc from the stellar emission and instead coincide with tidal debris. The authors note that the gas may retain angular momentum from the progenitor disks and continue to exhibit disk-like rotation, but they also consider ram-pressure stripping as a possible mechanism in the protocluster environment.

Resolving whether a several-kiloparsec displacement is compatible with coherent gas rotation would clarify the physical origin of the displaced gas and the mechanisms shaping merger evolution in the protocluster core.

References

However, it is unclear whether this gas reservoir can be displaced by such a magnitude (several kpc) while still exhibiting evidence of coherent rotation.

— The Koi Pond: A Strongly Lensed Protocluster Core hosting a Diverse Population of DSFGs  (2608.15997 - Foo et al., 17 Aug 2026) in Section 4.1, subsubsection “Tidally Displaced Gas Reservoir?”