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DTSTART;TZID=America/New_York:20230202T093000
DTEND;TZID=America/New_York:20230202T103000
DTSTAMP:20260504T005806
CREATED:20230817T182911Z
LAST-MODIFIED:20240118T092235Z
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SUMMARY:Near extremal de Sitter black holes and JT gravity
DESCRIPTION:General Relativity Seminar \nSpeaker: Chiara Toldo (Harvard) \nTitle: Near extremal de Sitter black holes and JT gravity \nAbstract: In this talk I will explore the thermodynamic response near extremality of charged black holes in four-dimensional Einstein-Maxwell theory with a positive cosmological constant. The latter exhibit three different extremal limits\, dubbed cold\, Nariai and ultracold configurations\, with different near-horizon geometries. For each of these three cases I will analyze small deformations away from extremality\, and construct the effective two-dimensional theory\, obtained by dimensional reduction\, that captures these features. The ultracold case in particular shows an interesting interplay between the entropy variation and charge variation\, realizing a different symmetry breaking with respect to the other two near-extremal limits.
URL:https://cmsa.fas.harvard.edu/event/gr_2223/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-02.03.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230209T133000
DTEND;TZID=America/New_York:20230209T143000
DTSTAMP:20260504T005806
CREATED:20230817T183342Z
LAST-MODIFIED:20240215T100720Z
UID:10001253-1675949400-1675953000@cmsa.fas.harvard.edu
SUMMARY:Quasinormal modes and Ruelle resonances: mathematician's perspective
DESCRIPTION:General Relativity Seminar \nSpeaker: Maciej Zworski\, UC Berkeley \nTitle: Quasinormal modes and Ruelle resonances: mathematician’s perspective \nAbstract: Quasinormal modes of gravitational waves and Ruelle resonances in hyperbolic classical dynamics share many general properties and can be considered “scattering resonances”: they appear in expansions of correlations\, as poles of Green functions and are associated to trapping of trajectories (and are both notoriously hard to observe in nature\, unlike\, say\, quantum resonances in chemistry or scattering poles in acoustical scattering). I will present a mathematical perspective that also includes zeros of the Riemann zeta function (scattering resonances for the Hamiltonian given by the Laplacian on the modular surface) and stresses the importance of different kinds of trapping phenomena\, resulting\, for instance\, in fractal counting laws for resonances.
URL:https://cmsa.fas.harvard.edu/event/gr_2023/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-02.09.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230216T133000
DTEND;TZID=America/New_York:20230216T143000
DTSTAMP:20260504T005806
CREATED:20230817T183826Z
LAST-MODIFIED:20240118T092821Z
UID:10001254-1676554200-1676557800@cmsa.fas.harvard.edu
SUMMARY:Quasinormal Modes from Penrose Limits
DESCRIPTION:General Relativity Seminar \nSpeaker: Kwinten Fransen (UC Santa Barbara) \nTitle: Quasinormal Modes from Penrose Limits \nAbstract: In this talk\, I will explain how to describe quasinormal modes with large real frequencies using Penrose limits. To do so\, I first recall relevant aspects of the Penrose limit\, and its resulting plane wave spacetimes\, as well as quasinormal modes to subsequently tie these together. Having established the main principle\, I will illustrate the usefulness of this point of view with the geometric realization of the emergent symmetry algebra underlying the quasinormal modes in the large real frequency limit and present its application to the astrophysically important example of Kerr black holes. Based on arXiv:2301.06999.
URL:https://cmsa.fas.harvard.edu/event/gr_21623/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-02.16.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230223T093000
DTEND;TZID=America/New_York:20230223T103000
DTSTAMP:20260504T005806
CREATED:20230817T184650Z
LAST-MODIFIED:20240118T093227Z
UID:10001255-1677144600-1677148200@cmsa.fas.harvard.edu
SUMMARY:Formation of trapped surfaces in the Einstein-Yang-Mills system
DESCRIPTION:General Relativity Seminar \nSpeaker: Nikolaos Athanasiou (University of Crete\, Greece) \nTitle: Formation of trapped surfaces in the Einstein-Yang-Mills system \nAbstract: The purpose of this talk is to give an overview of a semi-global existence result and a trapped surface formation results in the context of the Einstein-Yang-Mills system. Adopting a “signature for decay rates” approach first introduced by An\, we develop a novel gauge (and scale) invariant hierarchy of non-linear estimates for the Yang-Mills curvature which\, together with the estimates for the gravitational degrees of freedom\, yield the desired semi-global existence result. Once semi-global existence has been established\, we will explain how the formation of a trapped surface follows from a standard ODE argument. This is joint work with Puskar Mondal and Shing-Tung Yau.
URL:https://cmsa.fas.harvard.edu/event/gr_22323/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-02.23.23.png
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