2026ApJ...998..173C

M dwarfs are magnetically active stars that frequently produce flares, which have implications for both stellar evolution and exoplanet studies. Flare occurrence rates and activity levels of M dwarfs correlate with stellar characteristics such as age, mass, and rotation period. We search TESS observations of a known active population of M dwarfs as well as a volume-limited sample of M dwarfs within 15 pc. We detect flares in the light curves of these stars, including 276 of 538 M dwarfs within 15 pc, and calculate cumulative flare frequency distributions (FFDs) for each star. Based on flaring behavior, we categorize stars into relatively higher- and lower-activity groups and fit power laws to their FFDs to compare the power-law exponent (α) across activity levels. We find α = 1.99 ± 0.07 for the combined FFD of the lower-activity M dwarfs, compared to averages of α = 1.94 ± 0.58 for highly active stars with 10-100 detected flares, and α = 2.03 ± 0.43 for those with >100 detected flares, suggesting little evolution in the power-law distribution of flares as M dwarfs transition from high- to low-activity states. The uncertainties for the active star groups reflect the standard deviation of α values across individual stars within each subset. Because stellar flares and associated stellar activity complicate exoplanet observations, we also examine the subset of M dwarfs with James Webb Space Telescope (JWST) transmission spectroscopy follow-up observations in Cycles 1-3. The flares we detect for these targets are consistent with the broader 15 pc sample, providing context for interpreting planetary atmosphere retrievals from JWST spectra.