Astronomy Cast Ep. 755: Intermediate Mass Black Holes By Fraser Cain & Dr. Pamela Gay Streamed live on May 5, 2025. Hosted by: Fraser Cain and Dr. Pamela L. Gay. There are stellar-mass and supermassive black holes. But very little evidence of anything in between. Where are all the intermediate-mass black holes that should be the building blocks of the biggest ones? Actually, the science has been accelerating rapidly and we now know of hundreds of them. The question marks in our understanding are slowly getting replaced with data. Let's review what we now know about intermediate mass black holes and their origins.    SUPPORTED BY YOU! This Episode is made possible thanks to our Patrons on Patreon. Join at the Galaxy Group level or higher to be listed in our YouTube videos. Thanks to: BogieNet, Stephen Vei, Jeanette Wink, Siggi Kemmler, Andrew Poelstra, Brian Cagle, David Truog, Ed, David, Gerhard Schwarzer, Sergio Sancevero, Sergey Manouilov, Burry Gowen, David Rossetter, Michael Purcell, Jason Kwong