Retrieving "Sky Survey" from the archives

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1. Cosmic String

   Linked via "sky surveys"

   A straight, infinitely long cosmic string creates a characteristic double-image gravitational lens effect. Objects positioned directly behind the string appear as two distinct images positioned symmetrically around the string's apparent location. The deflection angle $\hat{\alpha}$ is independent of the impact parameter (for small angles) and is dependent solely on the string tension/} $T$ and the speed of light $c$:
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