Origin of the high-energy drop-off in M-dwarf flare frequency distributions

Determine whether the observed drop-off in flare frequency at bolometric energies above 10^35 erg in the combined CHEOPS and TESS M-dwarf flare frequency distributions reflects an intrinsic physical cutoff in flare generation or results from observational limitations such as limited observing baselines and detection incompleteness.

Background

The paper combines flare observations from TESS and CHEOPS for 110 M dwarfs, applies flare decomposition and detection-bias corrections, and constructs flare frequency distributions (FFDs) in terms of equivalent duration and bolometric energy. While ED-based FFDs follow a power law, energy-based FFDs are better modeled by a truncated power law with a break near 10^33 erg.

Despite correcting low-energy biases and identifying a truncated behavior, the authors report a drop-off in flare frequency above 10^35 erg whose cause is not established. They suggest it may indicate either a true physical cutoff in flare generation mechanisms or be an artifact of limited current observations, and note that future missions such as PLATO could explore this regime.