Authors: Trevor A. Bowen (UC Berkeley), Ben Chandran (UNH), Jonathan Squire (Univ. Otago), Stuart D. Bale (UC Berkeley),Die Duan (Peking University), Kristopher G. Klein (U. Arizona), Davin Larson (UC Berkeley), Alfred Mallet (UC Berkeley), Michael D. McManus (UC Berkeley), Romain Meyrand (U. Otago), J.L. Verniero (GSFC), Lloyd D. Woodham (Imperial)

The dissipation of magnetized turbulence is an important paradigm for describing heating and energy transfer in astrophysical environments such as the solar corona and wind; however, the specific collisionless processes behind dissipation and heating remain relatively unconstrained by measurements. In the solar wind, in situ magnetic field measurements reveal the presence of cyclotron waves, while measured ion velocity distribution functions have previously hinted at the presence of active cyclotron resonance. Here, we present Parker Solar Probe observations that connect observed spectrum of ion-cyclotron waves directly to signatures of resonant heating in proton distributions using quasilinear theory. We show that the quasilinear evolution of the observed distribution functions should absorb the observed cyclotron wave population with an average heating rate of 10^-14 W/m^3, indicating potential significant heating of the solar wind.