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The extreme contrast ratios between stars and their planets at opticalwavelengths make it challenging to isolate the light reflected by exoplanetatmospheres. Yet, these reflective properties reveal key processes occurring inthe atmospheres, and they also span wavelengths that include the potentialO$_2$ biosignature. High resolution cross-correlation spectroscopy (HRCCS)offers a robust avenue for developing techniques to extract exoplanetreflection spectra. We aimed to extract the optical reflected light spectrum ofthe non-transiting hot Jupiter 51 Peg b by adapting techniques designed toremove tellurics in infrared HRCCS to instead remove optical stellar lines.Importantly, we investigated the so far neglected impact of the broadening ofthe reflected host star spectrum due to the difference between the stellarrotation and the planet's orbital velocity. We used 484, R=115000 opticalspectra of 51 Peg b from HARPS-N and HARPS, which we aligned to the exactstellar rest frame in order to effectively remove the contaminating host star.However, some stellar residuals remained, likely due to stellar activity. Wecross-correlated with an appropriately broadened synthetic stellar model tosearch for the planet's Doppler-shifting spectrum. We detect no significantreflected light from 51 Peg b and report a S/N=3 upper limit on the contrastratio of 76.0 ppm (7.60x10$^{-5}$) when including broadening, and 24.0 ppm(2.40x10$^{-5}$) without. These upper limits rule out radius and albedocombinations of previously claimed detections. Broadening can significantlyimpact the ability of HRCCS to extract reflected light spectra and must beconsidered when determining the contrast ratio, radius, and albedo of theplanet. Asynchronous systems (Prot,$_{\star}\ne$ Porb) are most affected,including most hot Jupiters as well as Earth-size planets in the traditionalhabitable zones of some M-dwarfs.

Black Mirror: The impact of rotational broadening on the search for reflected light from 51 Pegasi b with high resolution spectroscopy