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The distortions of absorption line profiles caused by photospheric brightnessvariations on the surfaces of cool, main-sequence stars can mimic or overwhelmradial velocity (RV) shifts due to the presence of exoplanets. The latestgeneration of precision RV spectrographs aims to detect velocity amplitudes$\lesssim 10$ cm s$^{-1}$, but requires mitigation of stellar signals.Statistical techniques are being developed to differentiate between Keplerianand activity-related velocity perturbations. Two important challenges, however,are the interpretability of the stellar activity component as RV models becomemore sophisticated, and ensuring the lowest-amplitude Keplerian signatures arenot inadvertently accounted for in flexible models of stellar activity. For theK2V exoplanet host $\epsilon$ Eridani, we separately use ground-basedphotometry to constrain Gaussian processes for modeling RVs and TESS photometrywith a light-curve inversion algorithm to reconstruct the stellar surface. Fromthe reconstructions of TESS photometry, we produce an activity model, whichreduces the rms scatter in RVs obtained with EXPRES from 4.72 m s$^{-1}$ to1.98 m s$^{-1}$. We present a pilot study using the CHARA Array and MIRC-X beamcombiner to directly image the starspots seen in the TESS photometry. With thelimited phase coverage, our spot detections are marginal with current data buta future dedicated observing campaign should allow for imaging, as well as thestellar inclination and orientation with respect to its debris disk to bedefinitely determined. This work shows that stellar surface maps obtained withhigh cadence, time-series photometric and interferometric data can provide theconstraints needed to accurately reduce RV scatter.

EXPRES. III. Revealing the Stellar Activity Radial Velocity Signature of $\epsilon$ Eridani with Photometry and Interferometry