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Dark Matter Substructure Probed by Strong Gravitational Lenses. Aliza Malz Leonidas Moustakas and Jason Rhodes SURF 2007. Gravitational Lensing. Mass bends spacetime Light distorted near mass Observe image caused by gravity Learn about dark matter. Strong vs. Microlensing.
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Dark Matter Substructure Probed by Strong Gravitational Lenses Aliza Malz Leonidas Moustakas and Jason Rhodes SURF 2007
Gravitational Lensing • Mass bends spacetime • Light distorted near mass • Observe image caused by gravity • Learn about dark matter
Strong vs. Microlensing • Strong lensing multiplies images • Microlensing distorts magnification of images
The Lens Equation • = - • = - x DS/DLS • = - x DLS/DS • DS = DS - DL
Caustic Maps * 2 * 4 Cusp Weak Fold • Map in source plane • Determines type of gravitational lensing
Display caustic maps Process magnification data Convolution Methods
Caustic Crossings • Motion of source over caustic map • Magnification over time or space reveals nature of dark matter • Identified by second derivative threshold on lightcurve • Learn nature of dark matter from caustic crossing
Source Size • α = 4GM/(c2b) • α(θ) = 4GM/(c2θdl) • θds = θsds + αdls • α(θ) = ds/dls (θ – θs) • θ - θs = 4GM/(θc2) dls/dsdl • θE = (4GM/c2 dls/dlds)1/2
Variations in Source Size • Ideally small = 0.001 Re • Observations = 0.1 – 1.0 Re • Simulations = 0.01 – 0.1 Re
Future Research • Eliminate convolution method • Average microlensing events to equate with strong lensing effect • Remove microlensing from strong lensed image
Acknowledgments • Leonidas Moustakas, Jason Rhodes • SFP, SURF, and Carol Casey • IDL • NASA’s IDLAstro Library • Leonidas Moustakas’ lamlib and eidol Libraries • Fanning Consulting’s coyote Library • Aaron Barth’s ATV Library • John Moustakas’ RED Library • Craig Markwardt’s CM Library • Chuck Keeton’s dma.100 software