North America at night from space

1. North America at night from space

4. What are some things we (you) understand about light? Light can be: broken up into component colors absorbed reflected Light has energy

5. Wavelengths of Light Gamma Ray Radio Visible X-ray Ultraviolet Infrared Bright matter can be dark at some wavelengths.

6. (Luckily) Earth’s atmosphere absorbs light

8. Dark Matter What is Dark Matter? Why so we think it exists? What is Dark Matter made of?

9. Dark Matter What is Dark Matter? Dark matter is the name given to matter that cannot be detected in ANY wavelength of light. Why so we think it exists? What is Dark Matter made of?

10. Dark Matterversus “Faint Matter”

11. M81-Spiral Galaxy Visible (Optical) Radio

12. M20 - The Trifid Nebula

13. Why study dark matter? • It is most of the matter in the universe! • Dark matter could comprise as much as 90% of the matter in the universe. • It impacts our understanding of the beginnings of the universe. That is, how stars, galaxies, and galaxy clusters are able to form both now and early on. • It’s important in determining the ultimate fate of the universe. • It has an affect on (biases) how the distant universe appears to us.

14. Dark Matter What is Dark Matter? Dark matter is the name given to matter that cannot be detected in ANY wavelength of light. Why so we think it exists? We see evidence of it by looking at Bright Matter. Because although it is dark it still has GRAVITY associated with it! What is Dark Matter made of?

15. Evidence for Dark Matter in the Milky Way • Motions of stars near the sun tell us that there must be dark matter in our galaxy beyond the location of the sun.

16. Evidence from other galaxies • The motions of stars and gas, i.e. measurements of galaxy rotation curves, show that matter MUST be located beyond the radius where stars and gas are observed.

17. Gravitational Lensing Distant Star At Earth LensedImage Massive object

18. Gravitational Lensing • Gravitational Lensing is one method by which we can determine the mass of galaxy or galaxy cluster. Image (ring) Object Lensing Galaxy or Galaxy Cluster (with Dark Matter) Observer at Earth

20. Dark Matter What is Dark Matter? Dark matter is the name given to matter that cannot be detected in ANY wavelength of light. Why so we think it exists? We see evidence of it by looking at Bright Matter. Because although it is dark it still has GRAVITY associated with it! What is Dark Matter made of? We don’t know!

21. What is Dark Matter? • Baryonic dark matter • Massive Compact Halo Objects (MaCHOs) • Brown dwarfs • Cooling white dwarfs • Black holes Gliese229B Black Hole Ring Nebula

22. What is Dark Matter? • Non-baryonic dark matter • Weakly Interacting Massive particles (WIMPs) • Hot Dark Matter • Neutrinos • Cold Dark Matter • Neutralinos • Axions

23. Summary To study astronomical objects we must rely only on the light we receive from them to do our experiments Therefore, Astronomers must understand something about light. We rely on objects that give off light to tell us about Dark Matter. We have a ways to go before we understand exactly what Dark Matter is but we see its effects in dramatic ways. Astronomy is FUN!

25. Comet McNaught over La Serena, Chile 2007

26. Pulkovo Observatory, St. Petersburg, Russia

28. That’s President Obama! That’s me!

29. Thank you!