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Measuring Galaxy Cluster Masses Using Gravitational Lensing
- 1. Measuring Galaxy ClusterMasses Using Gravitational Lensing Blake Nicholson Astronomy 320
- 2. Overview I. Introduction II. GalaxyClusters III. Methods to Measure Mass IV. History: Soldner, Einstein, Zwicky V. How Gravitational Lensing Works VI. References
- 3. Galaxy Clusters • Biggestgravitationally-collapsed objects • Contain between 50 and 1000 galaxies • Typical diameter of 2-10 Mpc • Typical masses of 1014 to 1015 • Velocity distributions between 800-1000 km/s
- 4. Methods to MeasureMass Stellar Light Velocity Dispersion X-Ray emission from Bresstrahlung mechanism Sunyaev-Zel’dovich effect Weak gravitational Lensing
- 5. History 1804 – JohannSoldner suggests light interacting gravitationally with massive object. 1911 – Albert Einstein does work on light beam deflection due to gravitational interactions. 1914 – Einstein’s predictions are wrong but are never measured due to the start of WWI. 1919 – Arthur Eddington confirms Einstein’s findings on General Relativity 1924 – Chwolson observes a ‘double star’ 1936 – Einstein publishes paper on gravitational lensings and ‘Einstein-Rings’ 1937 – Fritz Zwicky suggests using lensing to study galaxies. 1960’s – Quasar discovery strengthens gravitational lensing as a legitimate discovery method.
- 6. How Gravitational Lensing Works Bendingof light rays by a very large mass/energy distribution • Source: Where the light beams comes from • Lens: Dense region that deflects the light beams • Observer: Who sees lensing • Image: The object that the observer sees
- 7. Types of GravitationalLensing Strong Lensing: Einstein-Ring, Einstein Crosses, Multiple Images Weak Lensing: Galaxy Clusters, Useful for measuring mass, Large-Scale Universe Microlensing: Source appears brighter, extrasolar planets
- 8. Mass Measurement Using GravitationalLensing Weak gravitational lensing gives us statistical information about galaxy clusters that we can use to determine mass- related properties.
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