Finding Supermassive Black Holes with Pulsars - Aaron Johnson - 06/30/2023

Is it possible to detect the merger of supermassive black holes throughout the universe? How can we use the regular clocklike flashes from distant pulsars to search for gravitational waves? Join us for a 30-minute lecture investigating these "pulsar timing arrays" and black holes, followed by a panel Q&A consisting of several astrophysicists who made this discovery to answer your questions. Timestamps below:

00:00 Announcements
04:03 Intro to Gravitational Wave Presentation
04:41 Gravitational Wave Presentation
27:04 Q&A for Gravitational Wave Presentation
27:27 "Does the black hole size change the gravitational waves?"
28:09 "Where are the pulsars located for this study?"
28:38 "How do the gravitational waves change with black hole characteristics?"
31:00 Intermission
34:23 Q&A Panel Introductions
38:42 Q&A Panel
38:45 "How does distance to pulsar affect the measurement?"
40:21 "And how does it impact the gravitational wave detections?"
42:00 "Why does the correlation curve look like that?"
44:18 "Is there an explosion when black holes merge!"
45:13 "Can a black hole consume itself?"
48:52 "Can we determine the distribution of black holes from this measurement?"
50:55 "Can we identify individual black hole mergers with this measurement?"
53:55 "How well do we need to know the location of our planets to make this measurement?"
57:09 "Did these gravitational waves originate in the early universe?"
59:13 "When can we identify individual black hole mergers with this measurement?"
1:00:53 "In this measurement, how do you account for undiscovered objects?"
1:05:20 "What makes black holes dark?"
1:06:25 "Do the funadmental particles in black holes change during a merger?"
1:11:24 "How important is quantum computing in this field?"
1:14:00 "If a black hole disappears, would it affect Earth?"
1:15:22 "How did Einstein predict gravitational waves?"
1:18:38 "How are mergers between black holes different from black hole-neutron star mergers?"
1:21:21 "Can black holes lose mass or energy?"
1:24:26 "What does Hawking Radiation look like when released?"
1:25:51 "If the universe expands at faster than light speed, how do we detect waves from it?"
1:26:48 "Can we estimate the number of black hole binaries from this measurement?"
1:28:43 "Can black holes consume a galaxy? Is there a maximum black hole mass?"
1:32:37 "Can exotic matter play a role in black hole theory?"
1:35:08 "Why are there supermassive black holes at the centers of galaxies?"
1:40:30 "What is actually measured at the radio telescope for this discovery?"
1:42:55 "Can we use radio telescopes in orbit to make better images of black holes?"
1:46:00 "Are pulsars observed on existing radio telescopes or new specialty telescopes?"
1:48:23 "What makes a black hole inactive or active?"
1:52:32 "Can we create black holes and gravitational waves in the lab?"
1:54:21 "What would a single black hole merger look like in the pulsar signal?"
1:55:58 Concluding Remarks

Q&A Panelists from NANOGrav Team (Left to Right)

Dr. Aaron Johnson - Postdoctoral Fellow, Caltech
Dr. Patrick Meyers - Postdoctoral Fellow, Caltech
Sophie Hourihane - PhD Candidate, Caltech
Dr. Katerina Chatziioannou - Professor, Caltech
Dr. Joseph Lazio - Chief Scientist, NASA JPL

For a higher-level presentation at the level of professional scientists on this discovery, please see our Caltech Colloquium talk by Dr. Patrick Meyers: https://www.youtube.com/watch?v=b1GhSgC8wmw

Title: Merging Supermassive Black Holes & Pulsar Timing Arrays
Speaker: Aaron Johnson
Abstract:
Supermassive black holes lurk at the centers of most galaxies. When galaxies merge, their black holes are also predicted to merge, releasing vibrations in the surrounding spacetime known as gravitational waves. While we cannot directly see these gravitational waves, it may be possible to detect them by looking for irregularities in the clock-like flashes coming from distant rotating dead stars known as pulsars. By monitoring a large enough network of pulsars spread around our galaxy for these irregularities, astronomers may be able to detect supermassive black holes throughout the universe. Are the merging black holes really out there, and when will we find them? Join us to learn about these so-called "pulsar timing arrays" and how we can use them to study the most massive black holes in the universe.

Видео Finding Supermassive Black Holes with Pulsars - Aaron Johnson - 06/30/2023 канала Caltech Astro