Prof. Nicolas Yunes
\nUniversity of Illinois Urbana-Champaign<\/p>\n
What replaces Kerr when Einstein\u2019s equations are modified, how does such a black hole ring, and can gravitational-wave data tell the difference? Connecting these questions requires consistent descriptions of both the stationary geometry and its dynamical response. I will discuss recent progress in constructing rotating black-hole solutions and calculating their gravitational quasinormal modes in effective field theories of gravity. These calculations reveal parity-dependent frequency shifts and raise a deeper question: what symmetry protects the equality of the even- and odd-parity spectra of Kerr? I will describe a framework for understanding this isospectrality. Finally, I will show how theory-specific spectra enter ringdown models and allow current gravitational-wave observations to constrain departures from general relativity, emphasizing the assumptions and regimes of validity needed to connect these calculations to observational tests.<\/p>","excerpt":"
The Sound of Symmetry<\/strong> What replaces Kerr when Einstein\u2019s equations are modified, how does such a black hole ring, and can gravitational-wave data tell the difference? Connecting these questions requires consistent descriptions of both the stationary geometry and its dynamical response. I will discuss recent progress in constructing rotating black-hole solutions and calculating their gravitational quasinormal modes in effective field theories of gravity. These calculations reveal parity-dependent frequency shifts and raise a deeper question: what symmetry protects the equality of the even- and odd-parity spectra of Kerr? I will describe a framework for understanding this isospectrality. Finally, I will show how theory-specific spectra enter ringdown models and allow current gravitational-wave observations to constrain departures from general relativity, emphasizing the assumptions and regimes of validity needed to connect these calculations to observational tests.<\/p>","slug":"cgca-seminar-nicolas-yunes","image":false,"all_day":false,"start_date":"2026-11-06 13:00:00","start_date_details":{"year":"2026","month":"11","day":"06","hour":"13","minutes":"00","seconds":"00"},"end_date":"2026-11-06 14:00:00","end_date_details":{"year":"2026","month":"11","day":"06","hour":"14","minutes":"00","seconds":"00"},"utc_start_date":"2026-11-06 19:00:00","utc_start_date_details":{"year":"2026","month":"11","day":"06","hour":"19","minutes":"00","seconds":"00"},"utc_end_date":"2026-11-06 20:00:00","utc_end_date_details":{"year":"2026","month":"11","day":"06","hour":"20","minutes":"00","seconds":"00"},"timezone":"America\/Chicago","timezone_abbr":"CST","cost":"","cost_details":{"currency_symbol":"$","currency_code":"USD","currency_position":"prefix","values":[]},"website":"","show_map":true,"show_map_link":true,"hide_from_listings":false,"sticky":false,"featured":false,"categories":[{"name":"CGCA Seminars","slug":"cgca-seminars","term_group":0,"term_taxonomy_id":50,"taxonomy":"tribe_events_cat","description":"","parent":0,"count":81,"filter":"raw","id":46,"urls":{"self":"https:\/\/uwm.edu\/physics\/wp-json\/tribe\/events\/v1\/categories\/46","collection":"https:\/\/uwm.edu\/physics\/wp-json\/tribe\/events\/v1\/categories"}}],"tags":[],"venue":{"id":8746,"author":"1661","status":"publish","date":"2025-06-19 11:28:12","date_utc":"0000-00-00 00:00:00","modified":"2025-06-19 11:28:12","modified_utc":"0000-00-00 00:00:00","url":"https:\/\/uwm.edu\/physics\/venue\/kenwood-irc-2175\/","venue":"Kenwood IRC 2175","slug":"kenwood-irc-2175","city":"Milwaukee","country":"United States","state":"WI","zip":"53211","stateprovince":"WI","json_ld":{"@type":"Place","name":"Kenwood IRC 2175","description":"","url":"https:\/\/uwm.edu\/physics\/venue\/kenwood-irc-2175\/","address":{"@type":"PostalAddress","addressLocality":"Milwaukee","addressRegion":"WI","postalCode":"53211","addressCountry":"United States"},"telephone":"","sameAs":""},"show_map":true,"show_map_link":true,"global_id":"uwm.edu\/physics?id=8746","global_id_lineage":["uwm.edu\/physics?id=8746"]},"organizer":[{"id":1191,"author":"9647","status":"publish","date":"2014-08-14 09:48:12","date_utc":"2014-08-14 14:48:12","modified":"2025-09-25 13:25:41","modified_utc":"2025-09-25 18:25:41","url":"https:\/\/uwm.edu\/physics\/organizer\/leonard-e-parker-center-for-gravitation-cosmology-astrophysics\/","organizer":"Leonard E Parker Center for Gravitation, Cosmology & Astrophysics","slug":"leonard-e-parker-center-for-gravitation-cosmology-astrophysics","website":"https:\/\/cgca.uwm.edu\/","json_ld":{"@type":"Person","name":"Leonard E Parker Center for Gravitation, Cosmology & Astrophysics","description":"","url":"https:\/\/cgca.uwm.edu\/","telephone":"","email":"","sameAs":"https:\/\/cgca.uwm.edu\/"},"global_id":"uwm.edu\/physics?id=1191","global_id_lineage":["uwm.edu\/physics?id=1191"]}],"custom_fields":[],"json_ld":{"@context":"http:\/\/schema.org","@type":"Event","name":"CGCA Seminar – Nicolas Yunes","description":"<p><strong>The Sound of Symmetry<\/strong><br \/>\\nProf. Nicolas Yunes<br \/>\\nUniversity of Illinois Urbana-Champaign<\/p>\\n<p>What replaces Kerr when Einstein\u2019s equations are modified, how does such a black hole ring, and can gravitational-wave data tell the difference? Connecting these questions requires consistent descriptions of both the stationary geometry and its dynamical response. I will discuss recent progress in constructing rotating black-hole solutions and calculating their gravitational quasinormal modes in effective field theories of gravity. These calculations reveal parity-dependent frequency shifts and raise a deeper question: what symmetry protects the equality of the even- and odd-parity spectra of Kerr? I will describe a framework for understanding this isospectrality. 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\nProf. Nicolas Yunes
\nUniversity of Illinois Urbana-Champaign<\/p>\n