Multiwavelength Modeling of the Luminous Fast Blue Optical Transient AT2024wpp

TL;DR

AT2024wpp, a highly luminous LFBOT, is analyzed with a comprehensive multiwavelength dataset to identify a consistent physical origin. The authors fit an evolving blackbody and a broad set of semi-analytic optical models plus radio/X-ray afterglow/CSM/disc models using Bayesian inference. They find that no single model explains the full dataset; optical data require non-homologous, high-temperature conditions and early photosphere recession, while the radio/X-ray emission is best described by non-thermal synchrotron processes with possible jet components that fail to unify the bands. The favored scenario points to a stellar-mass/IMBH tidal disruption event with a synchrotron blast wave, though reprocessing winds and other channels remain plausible; late-time UV/X-ray observations could decisively test this interpretation.

Abstract

Luminous fast blue optical transients (LFBOTs) are a growing class of enigmatic energetic transients. They show fast rises and declines, high temperatures throughout their evolution, and non-thermal emission in radio and X-rays. Their power source is currently unknown, but proposed models include engine-driven supernovae, interaction-powered supernovae, shock cooling emission, intermediate mass black hole tidal disruption events (IMBH TDEs), and Wolf-Rayet/black hole mergers, among others. AT2024wpp is the most optically luminous LFBOT to date and has been observed extensively at multiple wavelengths, including radio, optical, UV, and X-rays. We take models from multiple scenarios and fit them to the AT2024wpp optical, radio, and X-ray light curves to determine if which of these scenarios can best describe all aspects of the data. We show that none of the multiwavelength light curve models can reasonably explain the data, although other physical arguments favour a stellar mass/IMBH TDE of a low mass star and a synchrotron blast wave. We discuss how this scenario can be tested with late-time observations, and what other scenarios could possibly explain the broadband data.

Figures (9)

• Figure 1: The multiband fit from the evolving blackbody (top) and the luminosity (second), radius (third), and temperature (bottom) derived from it. The shaded region shows the 90$\%$ credible interval. Values from Perley2026 are shown in red.
• Figure 2: The light curve fits to the broadband optical data for each model discussed in Section \ref{['sec:mods']} (see Table \ref{['tbl:models']}) using default priors. The solid line shows the model with the highest likelihood while the shaded region shows the 90$\%$ confidence interval.
• Figure 3: Same as Figure \ref{['fig:optfits_tfree']}, but with the prior for $T_{\rm floor}$ restricted to $<$ 10$^4$ K.
• Figure 4: The light curve fits to the radio and submillimetre (top) and X-ray (bottom) data for each model discussed in Section \ref{['sec:mods']} (see Table \ref{['tbl:models']}). The solid line shows the model with the highest likelihood while the shaded region shows the 90$\%$ confidence interval.
• Figure 5: Radio light curves using the posteriors from the X-ray fits (top) and X-ray light curves using the radio posteriors (bottom) (see Figure \ref{['fig:radx_lcs']} for the fits). The shaded region shows the 90$\%$ confidence intervals, while the solid line shows the model with the highest likelihood from the original fits.