Gravitational Lenses

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Gravitational Lenses

• Travis Fischer
• GSU Astronomy

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Outline

• What are gravitational lenses?
• How can we use them to measure distance?
• Why oh why is it so ridiculously hard?

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Star
Image
Star
POV Cam
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(No Transcript)
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Galaxy Lensing
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Quasar Lensing
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Distance Measurement

• We need to know
• Time delay of background source
• Separation of background source images
• Relative distances of lens and background source
• Mass of lens and its distribution

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Time Delay
2nd
1st
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Time Delay - Q0957561
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(No Transcript)
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Lens Optics
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Distance
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Problems

• Distance relies on Ho
• Mass distribution models
• Lenses arent common
• CASTLeS

QSO 0957061 Ho63/-12 km/s Mpc-1 PG
1115080 Ho42 km/s Mpc-1 Ho60/-17 km/s
Mpc-1 B 1600434 Ho52/-14 km/s Mpc-1 B
1608656 Ho63/-15 km/s Mpc-1 0218357 Ho71/
-20 km/s Mpc-1
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References

• Blandford, R.D., Narayan, R., Annual Review,
  1992, 30, 311
• Bernstein, G., Fischer, P., 1999, AJ, 118, 14
• Myers, S.T., 1999, Proc Natl Acad Sci USA,
  pubmedcentral.nih.gov
• Wambsganss, J., et al. Optical Light Curves