Dark matter substructure probed by strong gravitational lenses
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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

Dark Matter Substructure Probed by Strong Gravitational Lenses

Aliza Malz

Leonidas Moustakas and Jason Rhodes

SURF 2007


Gravitational lensing
Gravitational Lensing

  • Mass bends spacetime

  • Light distorted near mass

  • Observe image caused by gravity

  • Learn about dark matter


Strong vs microlensing
Strong vs. Microlensing

  • Strong lensing multiplies images

  • Microlensing distorts magnification of images


The lens equation
The Lens Equation

  •  =  - 

  •  = -  x DS/DLS

  •  =  -  x DLS/DS

  • DS = DS - DL


Caustic maps
Caustic Maps

* 2

* 4

Cusp

Weak

Fold

  • Map in source plane

  • Determines type of gravitational lensing


Methods

Display caustic maps

Process magnification data

Convolution

Methods


Caustic crossings
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
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
Variations in Source Size

  • Ideally small = 0.001 Re

  • Observations = 0.1 – 1.0 Re

  • Simulations = 0.01 – 0.1 Re



Future research
Future Research

  • Eliminate convolution method

  • Average microlensing events to equate with strong lensing effect

  • Remove microlensing from strong lensed image


Acknowledgments
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


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