A A   
Connect with us:      
Le contenu de cette page n’est pas disponible en français. Veuillez nous en excuser.
 

Quantum Black Holes in the Sky?

Conference Date: 
Mercredi, Novembre 8, 2017 (All day) to Vendredi, Novembre 10, 2017 (All day)
Scientific Areas: 
Quantum Fields and Strings
Quantum Gravity
Quantum Information
Strong Gravity

The past decade has witnessed significant breakthroughs in understanding the quantum nature of black holes, with insights coming from quantum information theory, numerical relativity, and string theory.  At the same time, astrophysical and gravitational wave observations can now provide an unprecedented window into the phenomenology of black hole horizons.  This workshop seeks to bring together leading experts in these fields to explore new theoretical and observational opportunities and synergies that could improve our physical understanding of quantum black holes.

Original artwork by Kaća Bradonjić inspired by Niayesh Afshordi's talk
"Reflections on Spacetime."  Part of the “Projections” series.

  • Jahed Abedi, Institute for Research in Fundamental Sciences
  • Valentina Baccetti, Macquarie University
  • Carlos Barcelo, Institute of Astrophysics of Andalusia
  • Iosif Bena, CEA-Saclay
  • Ofek Bimholtz, Albert Einstein Institute
  • Avery Broderick, Perimeter Institute & University of Waterloo
  • Ramy Brustein, Ben Gurion University
  • Katerina Chatziioannou, CITA
  • Roberto Emparan, Catalan Institution for Research and Advanced Studies
  • Archisman Ghosh, International Centre for Theoretical Sciences
  • Steve Giddings, University of California, Santa Barbara
  • Shaun Hampton, Ohio State University
  • Chad Hanna, Pennsylvania State University
  • James Hartle, University of California, Santa Barbara
  • Thomas Hertog, University of Leuven
  • Yinzhe Ma, University of KwaZulu-Natal
  • Emil Martinec, University of Chicago
  • Emil Mottola, Los Alamos National Lab
  • Alex Nielsen, Albert Einstein Institute
  • Don Page, University of Alberta
  • Paolo Pani, Sapienza University of Rome
  • Jing Ren, University of Toronto
  • Ulrich Sperhake, University of Cambridge
  • David Turton, University of Southampton
  • Julian Westerweck, Albert Einstein Institute
  • Helvi Witek, University of Barcelona
  • Kento Yagi, University of Virginia
  • Yuki Yokokura, RIKEN
  • Aaron Zimmerman, CITA
  • Jahed Abedi, Institute for Research in Fundamental Sciences
  • Niayesh Afshordi, Perimeter Institute & University of Waterloo
  • Valentina Baccetti, Macquarie University
  • Carlos Barcelo, Institute of Astrophysics of Andalusia
  • Itzhak Bars, University of Southern California
  • Iosif Bena, CEA-Saclay
  • Ofek Bimholtz, Albert Einstein Institute
  • Avery Broderick, Perimeter Institute & University of Waterloo
  • Ramy Brustein, Ben Gurion University
  • Pablo Cano, Instituto de Física Teórica UAM/CSIC
  • Raul Carball-Rubio, SISSA
  • Vitor Cardoso, Perimeter Institute & Universidade de Lisboa
  • Katerina Chatziioannou, CITA
  • Randy Conklin, University of Toronto
  • William Cook, University of Cambridge
  • Francois David, CEA-Saclay
  • Roberto Emparan, Catalan Institution for Research and Advanced Studies
  • Archisman Ghosh, International Centre for Theoretical Sciences
  • Steve Giddings, University of California, Santa Barbara
  • Anuradha Gupta, Pennylvania State University
  • Shaun Hampton, Ohio State University
  • Chad Hanna, Pennsylvania State University
  • James Hartle, University of California, Santa Barbara
  • Thomas Hertog, University of Leuven
  • Bob Holdom, University of Toronto
  • Matthew Johnson, Perimeter Institute & York University
  • Yinzhe Ma, University of KwaZulu-Natal
  • Emil Martinec, University of Chicago
  • Samir Mathur, Ohio State University
  • John Moffat, Perimeter Institute
  • Emil Mottola, Los Alamos National Lab
  • Alex Nielsen, Albert Einstein Institute
  • Nestor Ortiz, Perimeter Institute
  • Don Page, University of Alberta
  • Paolo Pani, Sapienza University of Rome
  • Jing Ren, University of Toronto
  • Matthew Robbins, Perimeter Institute
  • Marcelo Rubio, Universidad de Cordoba
  • Barak Shoshany, Perimeter Institute
  • Ulrich Sperhake, University of Cambridge
  • David Turton, University of Southampton
  • Julian Westerweck, Albert Einstein Institute
  • Helvi Witek, University of Barcelona
  • Kento Yagi, University of Virginia
  • Yuki Yokokura, RIKEN
  • Jun Zhang, Perimeter Institute & York University
  • Aaron Zimmerman, CITA

Wednesday, November 8, 2017

Time

Event

Location

8:30 – 9:00am

Registration

Reception

9:00 – 9:20am

Paolo Pani, Sapienza University of Rome
Quantifying the Evidence for Black Holes with
GW and EM Probes

Bob Room

9:20 – 9:40am

Jahed Abedi, Institute for Research in Fundamental Sciences
Echoes from the Abyss: Tentative Evidence for Planck-Scale Structure at Black Hole Horizons

Bob Room

9:40 – 10:00am

Alex Nielsen, Albert Einstein Institute
TBA

Bob Room

10:00 – 10:30am

Coffee Break

Bistro – 1st Floor

10:30 – 10:50am

Archisman Ghosh, International Centre for Theoretical Sciences
A Model-Independent Search for Gravitational-Wave Echoes

Bob Room

10:50 – 11:10am

Julian Westerweck, Albert Einstein Institute
TBA

Bob Room

11:10 – 12:00pm

Discussion: Evidence for Echoes

Bob Room

12:00 – 2:00pm

Lunch

Bistro – 2nd Floor

2:00 – 2:20pm

Kento Yagi, Princeton University
TBA

Bob Room

2:20 – 2:40pm

Aaron Zimmerman, CITA
A Recipe for Echoes

Bob Room

2:40 – 3:00pm

Ofek Bimholtz, Albert Einstein Institute
Testing Pseudo-Complex General Relativity with Gravitational Waves

Bob Room

3:00 – 3:30pm

Coffee Break

Bistro – 1st Floor

3:30 – 3:50pm

Katerina Chatziioannou, CITA
Measuring the Polarization Content of
Gravitational Waves with LIGO

Bob Room

3:50 – 4:10pm

Chad Hanna, Pennsylvania State University
TBA

Bob Room

4:10 – 5:00pm

Discussion: Testing Gravity with LIGO

Bob Room

 
Thursday, November 9, 2017

Time

Event

Location

9:00 – 9:20am

David Turton, University of Southhampton
Black Hole Microstates in String Theory

Bob Room

9:20 – 9:40am

Shaun Hampton, Ohio State University
TBA

Bob Room

9:40 – 10:00am

Samir Mathur, Ohio State University
TBA

Bob Room

10:00 – 10:30am

Coffee Break

Bistro – 1st Floor

10:30 – 10:50am

Iosif Bena, CEA Saclay
Thou Shalt Not Put (Ordinary) Stuff at the Horizon

Bob Room

10:50 – 11:10am

Emil Martinec, University of Chicago
String Theory of Supertubes

Bob Room

11:10 – 12:00pm

Discussion: Why Fuzzballs?

Bob Room

12:00 – 2:00pm

Lunch

Bistro – 2nd Floor

2:00 – 2:20pm

Carlos Barcelo, Institute of Astrophysics of Andalusia
Probing Extreme Gravity in Stellar Collapse

Bob Room

2:20 – 2:40pm

Jing Ren, University of Toronto
From Quadratic Gravity to Observation

Bob Room

2:40 – 3:00pm

Steve Giddings, University of California,
Santa Barbara
Rescuing Quantum Mechanics with Soft Gravitational Structure: Postulates to Observational Prospects

Bob Room

3:00 – 3:30pm

Coffee Break

Bistro – 1st Floor

3:30 – 3:50pm

James Hartle, University of California,
Santa Barbara
TBA

Bob Room

3:50 – 4:10pm

Thomas Hertog, University of Leuven
Holographic Toy Model of AdS Black Holes

Bob Room

4:10 – 5:00pm

Discussion: Fate of Gravitational Collapse

Bob Room

5:00 – 6:00pm

Break

Bob Room

6:00 – 8:00pm

Banquet

Bistro – 2nd Floor

 

Friday, November 10, 2017

Time

Event

Location

9:00 – 9:20am

Yuki Yokokura, RIKEN
A Self-Consistent Model of
Evaporating Black Holes

Bob Room

9:20 – 9:40am

Emil Mottola, Los Alamos National Laboratory
TBA

Bob Room

9:40 – 10:00am

Valentina Baccetti, Macquarie University
TBA

Bob Room

10:00 – 10:30am

Coffee Break

Bistro – 1st Floor

10:30 – 10:50am

Don Page, University of Alberta
Qubit Model for Black Hole Evaporation
Without Firewalls

Bob Room

10:50 – 11:10am

Ramy Brustein, Ben Gurion University
TBA

Bob Room

11:10 – 12:00pm

Discussion: Firewalls! Why, or Why Not?

Bob Room

12:00 – 2:00pm

Lunch

Bistro – 2nd Floor

2:00 – 2:20pm

Roberto Emparan, University of Barcelona
Remarks on Cosmic Censorship and its
Possible Violations

Bob Room

2:20 – 2:40pm

Helvi Witek, University of Barcelona
Growing Black-Hole Hair in Extensions
of General Relativity

Bob Room

2:40 – 3:00pm

Ulrich Sperhake, University of Cambridge
Long-Lived Inverse Chirp Signals from Core-Collapse in Massive Scalar-Tensor Gravity

Bob Room

3:30 – 3:30pm

Coffee Break

Bistro – 1st Floor

3:30 – 3:50pm

Yinzhe Ma, University of KwaZulu-Natal
Black Hole Mining Effect

Bob Room

3:50 – 4:10pm

Avery Broderick, Perimeter Institute
TBA

Bob Room

4:10 – 5:00pm

Discussion: Quantum Black Holes in the Sky?

Bob Room

 

Jahed Abedi, Institute for Research in Fundamental Sciences

Echoes from the Abyss: Tentative Evidence for Planck-Scale Structure at Black Hole Horizons

In classical General Relativity (GR), an observer falling into an astrophysical black hole is not expected to experience anything dramatic as she crosses the event horizon. However, tentative resolutions to problems in quantum gravity, such as the cosmological constant problem, or the black hole information paradox, invoke significant departures from classicality in the vicinity of the horizon. It was recently pointed out that such near-horizon structures can lead to late-time echoes in the black hole merger gravitational wave signals that are otherwise indistinguishable from GR. We search for observational signatures of these echoes in the gravitational wave data released by advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), following the three black hole merger events GW150914, GW151226, and LVT151012. In particular, we look for repeating damped echoes with time-delays of 8MlogM (+spin corrections, in Planck units), corresponding to Planck-scale departures from GR near their respective horizons. Accounting for the "look elsewhere" effect due to uncertainty in the echo template, we find tentative evidence for Planck-scale structure near black hole horizons at false detection probability of 1% (corresponding to 2.5σ significance level). We also report the results of same search for echoes in the new black hole merger event GW170104.  Future observations from interferometric detectors at higher sensitivity, along with more physical echo templates, will be able to confirm (or rule out) this finding, providing possible empirical evidence for alternatives to classical black holes, such as in firewall or fuzzball paradigms.


Carlos Barcelo, Institute of Astrophysics of Andalusia

Probing Extreme Gravity in Stellar Collapse

The standard way to understand quantum corrected black holes leads to the information loss paradox and the lifetime dilemma. A radical way out of this situation is to give up a hypothesis which is tacitly assumed in the vast majority of works on the subject: that the classical singularity is substituted by something effectively acting as a sink for a long period of time, as seen by asymptotic observers.
Eliminating this characteristic changes drastically much of the physics now associated to black holes. A nice feature of the new hypothesis it that it offers a
clear possibility of experimental falsifiability with upcoming gravitational waves observations. In this talk I will discuss these possibilities.


Iosif Bena, CEA Saclay

Thou Shalt Not Put (Ordinary) Stuff at The Horizon

Black holes appear to lead to information loss, thus violating one of the fundamental tenets of Quantum Mechanics. Recent Information-Theory-based arguments imply that information loss can only be avoided if at the scale of the black hole horizon there exists a structure (commonly called fuzzball or

firewall) that allows information to escape. I will discuss the highly-unusual properties that this structure must have and how these properties emerge in the realization of this structure in String Theory via branes, fluxes and topology.


Ofek Birnholtz, Albert Einstien Institute

Testing pseudo-complex general relativity with gravitational waves

We show how the model of pseudo-complex general relativity can be tested using gravitational wave signals from coalescing compact objects. The Model, which agrees with Einstein gravity in the weak-field limit, diverges dramatically in the near-horizon regime, with certain parameter ranges excluding the existence of black holes. We show that simple limits can be placed on the model in both the inspiral and ringdown phase of coalescing compact objects.

We discuss further how these limits relate to current observational bounds.

In particular, for minimal scenarios previously considered in the literature, gravitational wave observations are able to constrain pseudo-complex general relativity parameters to values that require the existence of black hole horizons.


Katerina Chatziioannou, Canadian Institute for Theoretical Astrophysics

Measuring the polarization content of gravitational waves with LIGO

I will give a brief overview of LIGO’s efforts to test general relativity with gravitational waves. My main focus will be on tests of alternative polarizations.


Roberto Emparan, University of Barcelona

Remarks on Cosmic Censorship and Its Possible Violations


Archisman Ghosh, International Centre for Theoretical Sciences

A model-independent search for gravitational-wave echoes

Exotic compact objects (e.g. boson stars, dark matter stars, gravastars), and certain quantum modifications to black holes (e.g. firewalls) are speculated to give out ``echoes'' or bursts of radiation appearing at regular time intervals due to a perturbation by any infalling matter or field. In particular, these echoes are also expected to appear soon after their formation. The presence (or absence) of gravitational-wave echoes following observations of coalescences of compact binaries by detectors like Advanced LIGO and Virgo, might be able to directly probe (or constrain) the nature of the remnant compact object. For a large class of these objects, the echoes are expected to appear at time scales that are amenable to a search. However, there can be a substantial variation in the detailed waveform models, and this might make a template-based search inffective. We propose and demonstrate a model-independent search method that relies only on the constancy of the time difference between subsequent echoes.


Steven Giddings, University of California, Santa Barbara

Rescuing Quantum Mechanics with Soft Gravitational Structure: Postulates to Observational Prospects

Postulates are given for a quantum-gravitational description of black holes, that include correspondence with a quantum field theory description for freely falling observers crossing the horizon.  These lead to “soft gravitational structure,” which can transfer information to outgoing radiation either with or without large metric perturbations.  Prospects for observing such departures from the standard field-theoretic description of black holes will be briefly discussed.


Thomas Hertog, University of Leuven

Holographic Toy Model of AdS Black Holes


Yinzhe Ma, University of KwaZulu-Natal

Black Hole Mining Effect


Emil Martinec, University of Chicago

String Theory of Supertubes

The internal structure of extremal and near-extremal black holes in string theory involves a variety of ingredients — strings and branes — that lie beyond supergravity, yet it is often difficult to achieve quantitative control over these ingredients in a regime where the state being described approximates a black hole.  The supertube is a brane bound state that has been proposed as a paradigm for how string theory resolves black hole horizon structure.  This talk will describe how the worldsheet dynamics of strings can be solved exactly in a wide variety of supertube backgrounds, opening up the study of stringy effects in states near the black hole transition.


Don Page, University of Alberta

Qubit Model for Black Hole Evaporation without Firewalls

Kento Osuga and I give an explicit toy qubit transport model for transferring information from the gravitational field of a black hole to the Hawking radiation by a continuous unitary transformation of the outgoing radiation and the black hole gravitational field.  The model has no firewalls or other drama at the event horizon and fits the set of six physical constraints that Giddings has proposed for models of black hole evaporation.  It does utilize nonlocal qubits for the gravitational field but assumes that the radiation interacts locally with these nonlocal qubits, so in some sense the nonlocality is confined to the gravitational sector.  Although the qubit model is too crude to be quantitively correct for the detailed spectrum of Hawking radiation, it fits qualitatively with what is expected.


Paolo Pani, Sapienza University of Rome

Quantifying the evidence for black holes with GW and EM probes


Jing Ren, University of Toronto

From Quadratic Gravity to Observation

Astrophysical black hole candidates might be horizonless ultra-compact objects. Of particular interest is the plausible fundamental connection with quantum gravity. The puzzle is then why we shall expect Planck scale corrections around the horizon of a macroscopic black hole.

Taking asymptotically free quadratic gravity as a possible candidate of UV completion of general relativity, I will show how the would-be horizon can be naturally replaced by a tiny interior as dictated by the dynamics. The new horizonless 2-2-hole, as a quite generic static solution sourced by sufficiently dense matter, may then be the nearly black endpoint of gravitational collapse. In the era of gravitational wave astronomy, echoes in the post-merger phase provide a great opportunity to probe such scenario.

Given the uncertainties associated with the waveform of echoes, I will discuss some model-independent search strategies, where the primary task is to find the time delay between echoes. The search range is then motivated by the Planck scale deviation outside the would-be horizon.


Ulrich Sperhake, University of Cambridge

Long-Lived Inverse Chirp Signals from Core-Collapse in Massive Scalar-Tensor Gravity

We model stellar core collapse in massive scalar-tensor theories of gravity.

The presence of a mass term for the scalar field allows for dramatic increases in the radiated gravitational wave signal and may stretch out the signal to last for years or even centuries. There are several potential smoking gun signatures of a departure from general relativity associated with this process. These signatures could show up within existing LIGO-Virgo searches.


David Turton, University of Southhampton

Black Hole Microstates in String Theory

I will give an overview of recent work in the study of black hole microstates in string theory. I will describe constructions of smooth horizonless supergravity solutions, both supersymmetric and non-supersymmetric, and where applicable, their holographic description. I will also comment on the physics of an infalling observer.


Helvi Witek, University of Barcelona

Growing Black-Hole Hair in Extensions of General Relativity


Yuki Yokokura, RIKEN

A Self-consistent Model of Evaporating Black Holes

We analyze the time evolution of a spherically-symmetric collapsing matter from the point of view that black holes evaporate by nature. We obtain a self-consistent solution of the semi-classical Einstein equation. The solution indicates that the collapsing matter forms a dense object and evaporates without horizon or singularity, and it has a surface but looks like an ordinary black hole from the outside. Any object we recognize as a black hole should be such an object. In the case of stationary black holes that are formed adiabatically in the heat bath, the area law is reproduced by integrating the entropy density over the interior volume. This result implies that the information is stored inside the object.


Aaron Zimmerman, Canadian Institute for Theoretical Astrophysics

A Recipe for Echoes


 

 

Scientific Organizers:

  • Niayesh Afshordi, Perimeter Institute & University of Waterloo
  • Vitor Cardoso, Perimeter Institute & Universidade de Lisboa
  • Samir Mathur, Ohio State University