First measurement of gravitational lensing by cosmic voids in SDSS

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We report the first measurement of the diminutive lensing signal arising from matter underdensities associated with cosmic voids.

• While undetectable individually, by stacking the weak gravitational shear estimates around 901 voids detected in SDSS DR7 by Sutter et al.
• (2012a), we find substantial evidence for a depression of the lensing signal compared to the cosmic mean.
• This depression is most pronounced at the void radius, in agreement with analytical models of void matter profiles.