Dr. Andrea Derdzinski -- How do we see black holes?

In this week's episode, Dr. Abigail Polin joins us to answer your questions from the internet, on a variety of topics tangentially related to astrophysics! Questions range from the basic and fundamental to the obscure and weird. Answers are totally unprepared and rambling. Our guests this week are Dr. Abigail Polin, PLUS an extra-special mystery guest!

A black hole is so dense, its gravitational field prevents anything from escaping, including light. You would think that would make them the "blackest" things in the universe; how in the world do we know they are there? Dr. Andrea Derdzinski tells us about how we detect black holes, either due to the gravitational waves they produce, or due to their interaction with material orbiting around them, which paradoxically can make them some of the brightest objects in the universe.

Up in Orion's shoulder sits Betelgeuse, a supergiant star near the end of its life. The surface of Betelgeuse has been roiling and pulsing for centuries, as long as humans have recorded its modulated luminosity. Dr. Jared Goldberg is a postdoctoral research fellow at the Center for Computational Astrophysics in the Flatiron Institute in New York City. Dr. Golberg has been developing computer models for Betelgeuse to help understand and interpret its oscillations over time.

What happens when a black hole eats up a star? Apparently a lot of things happen, and if you wait around awhile and look in the radio, even more things happen! Dr. Yvette Cendes tells us what it's like to be a radio astronomer and about her latest research into tidal disruption events (TDE's), when a black hole shreds up a star and eats it, producing a dramatic light show across the electromagnetic spectrum.

Some things happen out in the universe that are too powerful to make in a lab. Other phenomena are so coherent and well-ordered, we can't figure out how they can be made without a lab! Fast radio bursts are an incomprehensible combination of both; they are extremely powerful, highly coherent, and very rapid bursts of radio emission. Dr. Maxim Lyutikov spends a lot of his time pondering how these bursts could possibly be made, and all the data seems to point to the most extreme physics imaginable: neutron stars at the highest densities we can imagine, with extremely strong gravity and with a magnetic field a quadrillion times stronger than the Earth's magnetic field.

How do we know so much about supernovae, when all we see is this little point of light getting brighter and then dimmer over time? Given this minimal data, we can often say what type of star exploded, and even some details about how the explosion took place. Supernova astronomers are a lot like forensic scientists dusting for fingerprints and getting DNA samples at the scene of a crime. But instead of a typical crime scene, they are investigating the death of an entire solar system. Dr. Lindsey Kwok is a CIERA fellow at Northwestern University and an expert at using JWST to perform state-of-the-art forensic supernova science.

How big a computer do you need to simulate a supernova? Or a planet being formed? Or a black hole swallowing gas? Many astrophysicists spend their time developing computational models to simulate these systems and learn how they evolve. We discuss these computer simulations with Purdue Professor Dr. Paul Duffell. In this first episode of season 2, Dr. Abigail Polin takes over as host.

What do black holes like to eat? Sometimes a steady diet of interstellar gas just isn't enough and a black hole needs to snack on a whole star. No judgment, we all get that way sometimes. But it can lead to some extremely energetic outflows, visible from across the universe. Dr. Brenna Mockler tells us all about these events, called "Tidal Disruption Events", and what we can learn from observing them.

Our universe isn't just a static, unchanging backdrop. It is constantly changing in time and we now have the technology to image it over and over again to explore all those changes. This is called Time Domain Astronomy, and Danny Milisavljevic is an expert in this field. He spends a lot of his time on the forensic science of exploding stars, to gain clues about the underlying processes that caused the explosion in the first place.

What would our solar system be like if we had two suns? Actually, this situation could be more common than you might think, as most stars are in binary systems. If a star is in a binary pair, how does that affect its life and death? Dr. Katelyn Breivik of Carnegie Mellon University tells us all about these systems and what scientists and other curious minds can learn from them.