Events Archive

Gravity Initiative Lunch, Martin Lesourd | Harvard BHI “ The Quasi-Local Penrose Inequality and the Hoop Conjecture”
Mon, Mar 9, 2020, 12:30 pm12:30 pm

The Spacetime Inequality of Penrose 1972 says that any slice in any black hole spacetime, the ADM mass of the slice is bounded below by the area of cuts with the event horizon. (Its quasi-local version is a refinement involving quasi-local notions of mass and energy). The Hoop Conjecture proposed by Thorne 1972 says that black holes form when…

Gravity Initiative Lunch, Maxime Van De Moortel | Princeton "The breakdown of weak null singularities inside black holes"
Mon, Mar 2, 2020, 12:30 pm12:30 pm

Abstract: The characterization of singularities inside black holes is a fundamental problem in General Relativity. While the celebrated “mass inflation” scenario suggests that a weakly *singular* Cauchy horizon forms inside generic black holes (near time-like infinity), the global structure of the black hole interior boundary has largely…

Gravity Initiative Lunch, Stephen Adler | IAS "Implications of a Frame-Dependent Dark Energy for the Spacetime Metric and "Hubble Tension""
Mon, Feb 24, 2020, 12:30 pm12:30 pm

Abstract:   I discuss the possibility that the ''dark energy'' that drives the accelerated expansion of the universe arises not from a conventional cosmological constant term in the gravitational action, but rather from a frame-dependent but Weyl scaling invariant action term.   This action mimics the standard cosmological action in an…

Gravity Initiative Lunch, Bart Ripperda | Princeton/Flatiron "Magnetic reconnection and plasmoid formation in black hole accretion flows"
Mon, Feb 17, 2020, 12:30 pm12:30 pm

Hot spots, or plasmoids, formed due to magnetic reconnection in thin current sheets are conjectured to power frequent bright X-ray and near-infrared flares from supermassive black holes, like Sgr A* in the center of our Galaxy. It is of yet unclear how, where, and when thin current sheets form in black hole accretion flows, and whether magnetic…

Gravity Initiative Lunch, Katerina Chatziioannou | CCA "Studying neutron stars with gravitational waves"
Mon, Feb 10, 2020, 12:30 pm12:30 pm

Neutron stars, the most dense astrophysical bodies we know of, are at the heart of many interesting astrophysical phenomena from their birth in supernova explosions to their deaths in collisions with other dense objects. Even though we have been witnessing the births of neutron stars in the night (or even day!) sky for thousands of years, the…

Gravity Initiative Lunch, Elias Most | Flatiron Institute "Constraints on nuclear physics and electromagnetic precursors from neutron star mergers"
Mon, Dec 2, 2019, 12:30 pm12:30 pm

With the detection of GW170817 we have observed the first multi-messenger gravitational wave signal from two merging neutron stars. This signal carried a multitude of information about the underlying equation of state (EOS) of nuclear matter, which so far is not known for densities above nuclear saturation. In particular it is not known if…

Gravity Initiative Lunch, Elena Giorgi | PGI, "The Teukolsky equations in Kerr-Newman spacetime"
Mon, Nov 25, 2019, 12:30 pm12:30 pm

The Kerr-Newman spacetime is the most general explicit black hole solution, and represents a stationary rotating charged black hole. Its stability to gravitational and electromagnetic perturbations has eluded a proof since the 80s in the black hole perturbation community. As put by Chandrasekhar, "the methods that have proved…

Gravity Initiative Lunch, Barak Zackay | IAS "Detecting Gravitational Waves With Disparate Detector Responses: Two New Binary Black Hole Mergers"
Mon, Nov 4, 2019, 12:00 pm12:00 pm

I will describe our continuing work for extracting the most of the LIGO-VIRGO data.
In this talk, I will discuss the process that was used to characterize the impact of non-Gaussian phenomena (so called 'Glitches')
I will then discuss the process that exploited the found properties in order to rank candidates based…