Great Lakes Lectures: How do we "see" black holes?

This talk was given in the Great Lakes Lectures series on May 27, 2021. Note that gifs and videos won't render in the pdf here.

Watch a video of me giving this talk (and struggle as a weather forecaster) here! https://www.facebook.com/101977881748388/videos/765172087493089

Description:
Black holes formed from dying stars are the densest things in the universe. They have ten to one hundred times the mass of the Sun crammed into a space that is only tens of miles across. Black holes get their name because their gravity is so strong that not even light can escape, so they look black to us. However, even though light can't escape from inside them, we still know where lots of them are. Scientists can find and study black holes from effects they have on the space environment around them. In this talk, I'll tell you about the ways we have of finding black holes and learning more about their extreme physics.

More information:
https://science.nasa.gov/astrophysics/focus-areas/black-holes https://wkar.pbslearningmedia.org/resource/black-holes-crashcourse-1033/black-holes-crash-course-astronomy/

Transcript

1. Image: NASA/JPL-Caltech How do we “see” black holes? Dr. Abbie Stevens Great Lakes Lectures
2. Black holes • A lot of stuff (mass) in a very small space • Very powerful gravity • Escape velocity faster than the speed of light! Image: J. Provost, ScienceNews.org imagine 3D space like a 2D fabric
3. Video: NASA/GSFC/J. Schnittman Black holes • Event horizon • Singularity • Photon sphere • Accretion disk Not pictured: relativistic jets The “danger zone” is very small!
4. Black holes Image: Event Horizon Telescope collaboration No limit on how big they can get! Small black holes are formed from the death and collapse of a big star (“stellar” or “stellar mass”) Big black holes have been around since very early in the universe, at the centers of galaxies (“supermassive”)
5. Black holes Image: Event Horizon Telescope collaboration No limit on how big they can get! Small black holes are formed from the death and collapse of a big star (“stellar” or “stellar mass”) Big black holes have been around since very early in the universe, at the centers of galaxies (“supermassive”) Quick interlude: Universe is really big, numbers get really big
6. Black holes Image: Event Horizon Telescope collaboration No limit on how big they can get! Small black holes are formed from the death and collapse of a big star (“stellar” or “stellar mass”) Big black holes have been around since very early in the universe, at the centers of galaxies (“supermassive”) Quick interlude: Universe is really big, numbers get really big 1 thousand seconds ≅ 16 minutes
7. Black holes Image: Event Horizon Telescope collaboration No limit on how big they can get! Small black holes are formed from the death and collapse of a big star (“stellar” or “stellar mass”) Big black holes have been around since very early in the universe, at the centers of galaxies (“supermassive”) Quick interlude: Universe is really big, numbers get really big 1 thousand seconds ≅ 16 minutes 1 million seconds ≅ 11 days
8. Black holes Image: Event Horizon Telescope collaboration No limit on how big they can get! Small black holes are formed from the death and collapse of a big star (“stellar” or “stellar mass”) Big black holes have been around since very early in the universe, at the centers of galaxies (“supermassive”) Quick interlude: Universe is really big, numbers get really big 1 thousand seconds ≅ 16 minutes 1 million seconds ≅ 11 days 1 billion seconds ≅ 32 years
9. Black holes Image: Event Horizon Telescope collaboration Biggest black hole ever seen: 60 Billion times the mass of our Sun Smallest black hole ever seen: 3 times the mass of our Sun No limit on how big they can get! Small black holes are formed from the death and collapse of a big star (“stellar” or “stellar mass”) Big black holes have been around since very early in the universe, at the centers of galaxies (“supermassive”)
10. Can’t just grab one, put it on a table, shine a light on it, and study it Video: NASA/GSFC/J. Schnittman How do we study them? To see it, need to wait for one to send light in our direction We “see” black holes by looking at effects on their space environment
11. Image: Event Horizon Telescope collaboration Taking a picture using radio light
12. Image: Event Horizon Telescope collaboration Taking a picture using radio light Computer simulation showing what it might look like if we had higher- resolution images
13. Image: NRAO/AUI Taking a picture using radio light
14. Image: ESO/O. Furtak Taking a picture using radio light
15. Taking a picture using radio light Image: NRAO
16. Image: Event Horizon Telescope collaboration Taking a picture using radio light Lines show polarization of the light
17. Image credit: NASA/CXC/M. Weiss Eating its star-friend (X-ray binaries) Star friend Black hole Accretion disk
18. Image credit: NASA/CXC/M. Weiss Star friend Black hole Accretion disk 20 million degrees F Eating its star-friend (X-ray binaries)
19. Video credit: NASA Eating its star-friend (X-ray binaries)
20. The first black hole we saw is called Cygnus X-1, in 1972. Eating its star-friend (X-ray binaries) Image credit: NASA/CXC/M. Weiss
21. Type of light Gets through Earth’s atmosphere? Approx. scale of wavelength? The electro-magnetic spectrum The colors that we see are a very small part of all the types of light that exist. Images: Shutterstock, NASA X-ray telescopes
22. The electro-magnetic spectrum Type of light Gets through Earth’s atmosphere? Approx. scale of wavelength Images: Shutterstock, NASA X-rays from space can’t get through Earth’s atmosphere, so we put X-ray telescopes on satellites and launch them into space on rockets! X-ray telescopes
23. Video: NASA/GSFC Image: Caltech X-ray telescopes
24. Eating other gas (AGN & quasars) Image credit: NASA/CXC/M. Weiss Chandra Deep Field Low X-ray Mid X-ray High X-ray Video: NASA/CXC/SAO/K. Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)
25. Black hole as ☆ Nearby orbiting stars Sagittarius A-star (Sgr A*) at the center of our Milky Way galaxy! 4.3 million times the mass of the Sun
26. Image credit: NASA/CXC/M. Weiss Smashing together Video: S. Ossokine/A. Buonanno/T. Dietrich (MPI for Gravitational Physics)/R. Haas (NCSA)/SXS project
27. Image credit: NASA/CXC/M. Weiss Smashing together Video: T. Pyle, Caltech/MIT/LIGO Lab LIGO Virgo
28. Image credit: NASA/CXC/M. Weiss Smashing together Image & video: Caltech/MIT/LIGO Lab
29. Image credit: NASA/CXC/M. Weiss Video: T. Ramirez/G. Lovelace/SXS Collaboration/LIGO-Virgo Collaboration Smashing together
30. Bending light from behind them
31. Bending light from behind them Image: NASA
32. Image: NASA/ESA/HST Bending light from behind them The strong gravity of the black hole acts like a lens, bending and distorting the image. Image: J. Rhoads(ASU)/WIYN/ AURA/NOAO/NSF
33. Bending light from behind them Image: NASA/ESA/HST
34. Image: NASA/JPL-Caltech How do we “see” black holes? Taking a picture using radio light Eating its star-friend Nearby orbiting stars Bending light from behind them Smashing together Eating other gas
35. Q&A time! Image: NASA/JPL-Caltech alstev@msu.edu @abigailStev github.com/abigailStev Dr. Abbie Stevens Great Lakes Lectures
36. Q&A time! Image: NASA/JPL-Caltech alstev@msu.edu @abigailStev github.com/abigailStev Dr. Abbie Stevens Great Lakes Lectures
37. Image credit: NASA/CXC/K. Divona
38. RXTE Science drivers: spin distribution of black holes, accretion disk winds, disk-jet connection, neutron star equation of state, burst oscillations, gamma-ray bursts, LIGO counterparts, tidal disruption events, discovering new sources, etc! Video from NASA Mission Design Lab, April 2018 § Proposed Probe-class space telescope, “medium” budget: $1B for development and 5 years of operations § Combines strengths of NICER and LOFT: high throughput X-ray timing with good spectroscopy § If selected, launch in 2032 on a Space-X Falcon Heavy