Physics

2018 Sep 04

What Exciting new Discoveries did you make this summer?

Location: 

BHI conference Room: 20 Garden Street, Cambridge (Lunch will be served at 1:00 pm)
1:30pm to 2:30pm

Director of the BHI, Avi Loeb will have an informal talk with members of the BHI community on new research and current ideas.
Zoe Zhu

Zoe Zhu

PhD student, BHI and Dept of Physics
Ziyan(Zoe) is a student at the BHI and in the department of Physics. She works with Professor Ramesh Narayan and Dr. Michael Johnson on the Event Horizon... Read more about Zoe Zhu
Carina Prunkl

Carina Prunkl

PhD student: University of Oxford
MSc in Physics: Freie Universitat, Berlin
MSt in Philosophy of Physics: University of Oxford

My current research focuses on the philosophy of black holes and the philosophy of science. I am particularly interested in black hole thermodynamics and...

Read more about Carina Prunkl
2018 May 09

Rainer Weiss to speak at BHI Conference Banquet May 9, 2018

Location: 

Sheraton Commander Hotel
6:00pm

 

Winning the Nobel Prize would cap most physicists’ careers. For 2017 winner Rainer Weiss, the prize might not even have been the biggest moment of his year.

The 85-year-old professor emeritus at MIT shared the Nobel Prize for Physics for conceiving and shepherding a set of observatories that allowed scientists to prove Einstein’s assertion about gravitational waves: accelerating objects send ripples cascading through the universe at light speed. The invisible waves are so faint that even the most powerful distort space-time by less than the width of a human...

Read more about Rainer Weiss to speak at BHI Conference Banquet May 9, 2018
2018 Apr 24

BHI Colloquium, April 24 | "Black Hole Entropy from Soft Hair" Malcolm Perry | "​Berry Phases of Boundary Gravitons" Blagoje Oblak | Lydia Bieri "Gravitational Wave Memory"

Location: 

BHI Conference Room (211) 20 Garden Street, Cambridge
1:30pm to 2:30pm

Blafoje Oblak

ETH Zurich

​Abstract:

This talk is devoted to Berry phases that appear in the context of asymptotic symmetries in general relativity. These phases arise when a coherent state is acted upon by symmetry transformations that trace a closed path in...

Read more about BHI Colloquium, April 24 | "Black Hole Entropy from Soft Hair" Malcolm Perry | "​Berry Phases of Boundary Gravitons" Blagoje Oblak | Lydia Bieri "Gravitational Wave Memory"
2018 Mar 27

BHI Colloquium, March 27 | "​On the distinguishability of black hole microstates," Andrea Puhm | "Discovery and Opportunity in the X-ray Time Domain," Daryl Haggard

Location: 

BHI Conference Room (211) 20 Garden Street, Cambridge
1:30pm

Andrea Puhm
CNRS researcher, CPHT, Ecole
Polytechnique, Black Hole Initiative Visiting Scholar

Title: On the distinguishability of black hole microstates

Abstract: ​A challenging question in the context of the information paradox is how to distinguish black hole microstates without having access to the entire spacetime. In the context of holography, one can ask how one can distinguish microstates of a black hole in anti-de Sitter space by measurements performed in the dual conformal field theory. I will discuss one...

Read more about BHI Colloquium, March 27 | "​On the distinguishability of black hole microstates," Andrea Puhm | "Discovery and Opportunity in the X-ray Time Domain," Daryl Haggard
2018 Feb 27

BHI Colloquium, February 27 | Angelo Ricarte | Erik Curiel

Location: 

BHI Conference Room (211) 20 Garden Street, Cambridge
1:30pm to 2:30pm

Angelo Ricarte
Yale University

​Title:  Modeling the Supermassive Black Hole and Host Galaxy Connection Over Cosmic Time

​Abstract:  Stellar and gas dynamics lead us to believe that a supermassive black hole (SMBH) lurks at the center of every massive galaxy.  Their masses correlate with host galaxy...

Read more about BHI Colloquium, February 27 | Angelo Ricarte | Erik Curiel
2018 Feb 20

BHI Colloquium, February 20 | "​​​​​​​On the optical/UV Emission from Tidal Disruption Events," Norman Murray | "Critical Emission from a High-Spin Black Hole," Yichen Shi

Location: 

BHI Conference Room (211) 20 Garden Street, Cambridge
1:30pm to 2:30pm

Norman Murray
University of Toronto

Abstract:
Over the last decade or so, dozens of x-ray or optical transient events have been detected towards the centers of (typically) low mass galaxies. They have been interpreted as the disruption of solar mass stars by the central supermassive black holes believed to lie in the centers of most galaxies. Such events were predicted in the 1970s. Early work indicated that the emission would be thermal, with temperatures of order 50 eV, arising from an accretion disk with an inner edge at or near the innermost stable circular orbit of the black hole, and would last a month or so. Loeb and Ulmer suggested that this disk radiation would be reprocessed into the near infrared, and that the event would last a decade or so. Early detections by ROSAT had spectral energy distributions (SEDs) dominated by soft x-rays. More recent events have been detected by optical transient surveys, and have SEDs dominated by UV emission. I will revisit the reprocessing arguments, and show that they actually predict that the emission should be in the UV rather than the near IR, and they further explain the observed constant effective temperature maintained while the luminosity first increases by a factor of ten, then decreases by a factor of 100.

Yichen Shi
Black Hole Initiative

Abstract:
We consider a rapidly spinning black hole surrounded by an equatorial, geometrically thin, slowly accreting disk that is stationary and axisymmetric. We analytically compute the broadening of electromagnetic line emissions from the innermost part of the disk, which resides in the near-horizon region. The result is independent of the details of the disk model and therefore universal. This is an example of critical behavior in astronomy that is potentially observable by current or future telescopes.

2018 Feb 06

BHI Colloquium, February 6 | ​​​​​​​"Nonlinear Evolution of the AdS_4 Black Hole Bomb," Paul Chesler | "Non-linear Stability via Global Analysis," Peter Hintz

Location: 

BHI Conference Room (211) 20 Garden Street, Cambridge
1:30pm to 2:30pm

"Nonlinear Evolution of the AdS_4 Black Hole Bomb"
Paul Chesler
Black Hole Initiative

Abstract: 
Energy may be extracted from rotating black holes via scattering involving superradiant modes. It was suggested some time ago that if such modes could be confined using a mirror, then an amplification process can occur, converting a significant fraction of the black hole mass into radiation, leading to a so-called "black hole bomb."  Anti-de Sitter spacetime contain a natural mirror - the timelike boundary of the geometry - and provides a tractable arena to study the nonlinear evolution of the black hole bomb.  Via numerically solving the full 3+1 dimensional Einstein equations, I will present evidence that the AdS black hole bomb is a multistage process.  Specifically, via superradiant gravitational modes, Kerr-AdS black holes transition to hairy black holes with a single Killing vector, which then experiences secondary weaker superradiant instabilities.


Peter Hintz
University of California, Berkeley

Abstract:
I will explain the point of view adopted in a number of recent works, joint with Andras Vasy, in which we prove the global non-linear stability of Minkowski space and of Kerr-(Newman-)de Sitter black holes. Instead of constructing and controlling the non-linear solution incrementally in time, we use a Newton-type iteration scheme: at each iteration step we solve a linearized equation globally. I will in particular address how this informs the choice of gauges, and highlight the crucial role played by constraint damping, first introduced as a tool in numerical relativity by Gundlach et al.

2017 Oct 17
2017 Oct 10

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