Resolving the host association of AT 2020afjz

Determine whether AT 2020afjz originated in a tidal star-forming structure associated with DES J042144.37-383311.3 and DES J042144.37-383313.0 or in a fainter undetected host galaxy near the transient position.

Background

The transient is localized approximately 2.6 arcseconds from the center of candidate host galaxy A, corresponding to a projected separation of about 18.9 kpc at the adopted photometric redshift. This large offset is in tension with the expected locations of collapsar progenitors in dense star-forming regions.

The authors consider two unresolved possibilities: a faint tidal knot associated with the interacting galaxy pair may lie near the transient, or the actual host may be a galaxy below the DECam detection limit. They state that deeper imaging and spectroscopy are needed to resolve this uncertainty.

References

Crucially, dense star forming regions required for the collapsar interpretation of AT 2020afjz\ are unlikely to exist at such a separation; however, it is possible that a faint tidal knot is present closer to the source position. Alternatively, the true host may be a faint galaxy below DECam detection limits.

— AT 2020afjz (TSS2020a): The First Fast Extragalactic Transient Discovered by TESS  (2608.17242 - Ridden-Harper et al., 18 Aug 2026) in Section 4.2, Host Identification; Section 5, Conclusion