Magnification cross sections for the elliptic umbilic caustic surface
© 2019 by the authors. In gravitational lensing, magnification cross sections characterize the probability that a light source will have magnification greater than some fixed value, which is useful in a variety of applications. The (area) cross section is known to scale as µ−2 for fold caustics and µ−2.5 for cusp caustics. We aim to extend the results to higher-order caustic singularities, focusing on the elliptic umbilic, which can be manifested in lensing systems with two or three galaxies. The elliptic umbilic has a caustic surface, and we show that the volume cross section scales as µ−2.5 in the two-image region and µ−2 in the four-image region, where µ is the total unsigned magnification. In both cases our results are supported both numerically and analytically.
Aazami, AB; Keeton, CR; Petters, AO
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