AT 2024wpp: the most luminous fast-evolving optical transient linked to the merger explosion of a black-hole binary

TL;DR

This paper reports the discovery of the most luminous fast blue optical transient, AT 2024wpp, linked to a black hole merger explosion, providing evidence that some FBOTs originate from tidal disruption events involving stellar black holes.

Contribution

It presents detailed observations and modeling of AT 2024wpp, establishing a connection between FBOTs and TDEs from stellar black hole mergers, a novel interpretation in the field.

Findings

AT 2024wpp shows luminosity decay consistent with TDEs.

Spectral analysis indicates accretion onto a black hole.

Modeling suggests a merger of a Wolf-Rayet star with a black hole.

Abstract

Fast blue optical transients (FBOTs) represent one of the most exotic astrophysical transients, exhibiting unusually strong emission across X-ray, optical, and radio wavelengths. Their physical origins remain highly debated, with proposed explanations ranging from stellar explosion to tidal disruption event (TDE). Here we report observations of the most luminous FBOT, AT 2024wpp whose post-peak luminosity rebrightens in X ray and becomes flattening in optical in a manner follows the decay rate characteristic of TDEs ($L_{\rm bol} \propto t^{-5/3}$). This invokes energy contribution of accretion by a central compact object, getting further corroborations from hardening of X-ray spectral index and detection of outflow inferred from the emission lines at similar phase. Detailed modeling of luminsoity evolution favors a coalesce explosion of a 34 M$_{\odot}$ Wolf-Rayet star with a 15 M$_{\odot}$ black hole (BH), demonstrating that some FBOTs may be associated with TDE of a stellar blackhole.