We present ages and masses for 601 star clusters in M31 from the analysis of the six filter integrated light measurements from near ultraviolet to near infrared wavelengths , made as part of the Panchromatic Hubble Andromeda Treasury ( PHAT ) .
We derive the ages and masses using a probabilistic technique , which accounts for the effects of stochastic sampling of the stellar initial mass function .
Tests on synthetic data show that this method , in conjunction with the exquisite sensitivity of the PHAT observations and their broad wavelength baseline , provides robust age and mass recovery for clusters ranging from \sim 10 ^ { 2 } -2 \times 10 ^ { 6 } \mathrm { ~ { } } _ { \odot } .
We find that the cluster age distribution is consistent with being uniform over the past 100 \mathrm { ~ { } } , which suggests a weak effect of cluster disruption within M31 .
The age distribution of older ( > 100 \mathrm { ~ { } } ) clusters fall towards old ages , consistent with a power-law decline of index -1 , likely from a combination of fading and disruption of the clusters .
We find that the mass distribution of the whole sample can be well-described by a single power-law with a spectral index of -1.9 \pm 0.1 over the range of 10 ^ { 3 } -3 \times 10 ^ { 5 } \mathrm { ~ { } } _ { \odot } .
However , if we subdivide the sample by galactocentric radius , we find that the age distributions remain unchanged .
However , the mass spectral index varies significantly , showing best fit values between -2.2 and -1.8 , with the shallower slope in the highest star formation intensity regions .
We explore the robustness of our study to potential systematics and conclude that the cluster mass function may vary with respect to environment .