Measuring Distances ASTR/PHYS 4080: Intro to Cosmology Week 6 - - PowerPoint PPT Presentation

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May 11, 2023 343 likes •546 views

Measuring Distances ASTR/PHYS 4080: Intro to Cosmology Week 6 ASTR/PHYS 4080: Introduction to Cosmology Spring 2018: Week 06 1 How do you measure distances when youre too lazy to get off the couch? TV is 6 or 7 years old, new TVs are

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Spring 2018: Week 06 ASTR/PHYS 4080: Introduction to Cosmology

Measuring Distances

ASTR/PHYS 4080: Intro to Cosmology Week 6

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Spring 2018: Week 06 ASTR/PHYS 4080: Introduction to Cosmology

How do you measure distances when you’re too lazy to get off the couch?

TV is 6 or 7 years old, new TVs are cheap, so it’s a great time to upgrade! Problem: I know roughly how much bigger I’d like the new TV to be (about or a little less than 2x bigger), but I don’t know how big my current TV is. How do I measure it? WITHOUT relinquishing my seat to the cat.

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Spring 2018: Week 06 ASTR/PHYS 4080: Introduction to Cosmology

Farther away things are fainter

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Spring 2018: Week 06 ASTR/PHYS 4080: Introduction to Cosmology

Angular extent depends on distance

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Spring 2018: Week 06 ASTR/PHYS 4080: Introduction to Cosmology

Practical Distance Measures

Luminosity Distance Angular Diameter Distance

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Spring 2018: Week 06 ASTR/PHYS 4080: Introduction to Cosmology

dL and dA in a universe with curvature

Robertson-Walker Metric flux affected by area of expanding shell of light angular extent affected by curvature of geodesics

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Spring 2018: Week 06 ASTR/PHYS 4080: Introduction to Cosmology

How distances are affected by underlying cosmology

Luminosity Distance Angular Diameter Distance

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Spring 2018: Week 06 ASTR/PHYS 4080: Introduction to Cosmology

Contemporary Measurements

Supernovae Luminosity Distances Megamaser Potential Promise of GW sources as “standard sirens”

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Spring 2018: Week 06 ASTR/PHYS 4080: Introduction to Cosmology

Distance Ladder

megamasers gravitational wave sources

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Spring 2018: Week 06 ASTR/PHYS 4080: Introduction to Cosmology

GW170817 NS-NS Merger

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