Tag Archives: black holes

Probing Effective Theories of Gravity in Strong Fields and Cosmology, Santa Barbara, USA

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Probing Effective Theories of Gravity in Strong Fields and Cosmology
KITP, UC Santa Barbara

Coordinators: Cora Dvorkin, Ira Rothstein, and Thomas Sotiriou
Scientific Advisors: Alessandra Buonanno, Pedro Ferreira, and Steve Giddings

There is strong evidence that General Relativity (GR) is only an effective field theory (EFT). While it is often assumed that the energy scale where the EFT breaks down is near the Planck scale and experimentally inaccessible, tantalizing arguments suggest that GR is not a canonical effective theory.

In particular, the apparent hints of non-locality in black hole evaporation and the small scale associated with the vacuum energy motivate reconsidering EFT ideas in gravity. Given the wealth of data in current and future high precision cosmological surveys, it is necessary to develop a tool kit of theoretically consistent EFTs for analyzing potential deviations from the predictions of GR. The birth of gravitational wave astronomy opens up other avenues for testing gravity in previously unimaginable ways, enabling the study of higher curvature backgrounds as well as black hole horizon physics.

This program is geared towards finding ways to push the boundaries of our knowledge of the EFT of GR by bringing together members of three distinct communities: strong gravity/relativistic astrophysics, cosmology, and EFT.

Primary Application Deadline: August 11th 2019. After that date application will continue to be considered in a rolling basis until the program is filled.

Please apply through the KITP website (link).

COST GWverse: Exchange of researchers working on gravitational-wave and black hole physics

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In the context of the European COST Action CA16104 on Gravitational waves, black holes and fundamental physics (GWverse), grants for short term scientific missions (STSMs) are available. We are inviting you to submit proposals for STMSs starting after May 1, 2019 and ending before Nov 30, 2019 (applications outside this timeframe will be discarded).

This call starts on Apr 1 and closes May 1, 2019. All proposals will be reviewed and the results will be announced by May 7, 2019.

The selection committee will take into account the geographical distribution of host and home institution, matching of funds by the host, the scientific proposal and the experience of the applicant (preference is given to Early Career Investigators).

Successful applicants will be expected to join as members of one (or more) of the Action’s Working Groups. STSM recipients should acknowledge the COST Action in any publication or talks, through the use of the COST logo and the statement “The authors would like to acknowledge networking support by the COST Action GWverse CA16104”.

STSMs are a great opportunity for all scientists within the COST Action to exchange visits, nurture collaborations, or develop new ones. Further details are available at the GWverse webpage: https://gwverse.tecnico.ulisboa.pt/stsms/
If you have any question, please contact the STSM Coordinator Andreja Gomboc: andreja.gomboc[at]ung.si

RELXILL_NK

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RELXILL_NK is a relativistic reflection model for testing Einstein’s theory of general relativity with black holes [1,2]. It is an extension of the RELXILL package [3,4] to non-Kerr spacetimes.

The study of the reflection spectrum of accretion disks around black holes is potentially a powerful tool to probe the strong gravity region of these objects. RELXILL_NK can calculate the reflection spectrum of accretion disks in parametric black hole spacetimes. Some “deformation parameters” quantify possible deviations from the Kerr background. From the comparison of X-ray data of astrophysical black holes with the theoretical predictions of RELXILL_NK we can measure these deformation parameters and check whether they vanish, as it would be required by general relativity.

The current public version of RELXILL_NK is 1.3.2 and employs the Johannsen metric with the deformation parameters alpha13 and alpha22 [5]. The model and the associated FITS files can be downloaded from one of the following servers:

Server at Fudan University (China):
http://www.physics.fudan.edu.cn/tps/people/bambi/Site/RELXILL_NK.html

Server at the University of Tuebingen (Germany):
http://www.tat.physik.uni-tuebingen.de/~nampalliwar/relxill_nk/

Support: relxill_nk[at]fudan.edu.cn

References:
[1] Bambi et al., ApJ 842, 76 (2017)
[2] Abdikamalov et al., arXiv:1902.09665
[3] Garcia et al., ApJ, 782, 76 (2014)
[4] Dauser et al., MNRAS, 444, 100 (2014)
[5] Johannsen, PRD 88, 044002 (2013)

RELXILL_NK is now public

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RELXILL_NK is a relativistic reflection model for testing Einstein’s theory of general relativity with black holes [1,2]. It is an extension of the RELXILL package [3,4] to non-Kerr spacetimes.

The study of the reflection spectrum of accretion disks around black holes is potentially a powerful tool to probe the strong gravity region of these objects. RELXILL_NK can calculate the reflection spectrum of accretion disks in parametric black hole spacetimes. Some “deformation parameters” quantify possible deviations from the Kerr background. From the comparison of X-ray data of astrophysical black holes with the theoretical predictions of RELXILL_NK we can measure these deformation parameters and check whether they vanish, as it would be required by general relativity.

The current public version of RELXILL_NK is 1.3.2 and employs the Johannsen metric with the deformation parameters alpha13 and alpha22 [5]. The model and the associated FITS files can be downloaded from one of the following servers:

Server at Fudan University (China):
http://www.physics.fudan.edu.cn/tps/people/bambi/Site/RELXILL_NK.html

Server at the University of Tuebingen (Germany):
http://www.tat.physik.uni-tuebingen.de/~nampalliwar/relxill_nk/

Support: relxill_nk[at]fudan.edu.cn

References:
[1] Bambi et al., ApJ 842, 76 (2017)
[2] Abdikamalov et al., arXiv:1902.09665
[3] Garcia et al., ApJ, 782, 76 (2014)
[4] Dauser et al., MNRAS, 444, 100 (2014)
[5] Johannsen, PRD 88, 044002 (2013)

Accretion in Strong Gravity, Bad Honnef, Germany

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The guiding theme of this seminar is the observation, the modelling and the theoretical description of accretion processes in systems where gravity is strong and nonlinear. Accreting matter are the objects which most closely approach compact objects like black holes or neutron stars and, therefore, are an ideal laboratory to explore the effects of strong gravity. Recently technological developments in observation techniques lead to a strongly improved accuracy in observing accretion discs and related phenomena. This trend will be continued in the next years, for instance with observations of ALMA and the James-Webb telescope, but also with survey telescopes like PanSTARRS or LSST. This development has to be paralleled by the theoretical description and modelling.

Basic open questions in accretion disc physics which will be discussed in this seminar include the description of viscosity and turbulence, in particular in the relativistic context, the effective equations of accretion, evolution of supermassive black holes, accretion discs in generalised theories of gravity, and GRMHD simulations. Summarized, the topics of this seminar are

Observation of astrophysical accretion and related phenomena
The basic equations of accretion and their structure
Applications to accretion discs and the accretion process
Numerical simulation of accretion in strong gravity

Confirmed invited speakers are so far
Prof. Dr. Axel Brandenburg
Prof. Dr. Wolfgang Duschl
Prof. Dr. Andreas Eckart
Prof. Dr. Jose Antonio Font
Prof. Dr. Domenico Giulini
PD Dr. Rodion Groll
Prof. Dr. John Hawley
Dr. Eva Hackmann
Dr. Tobias Illenseer
Prof. Dr. Vladimir Karas
Prof. Dr. Jutta Kunz
Prof. Dr. Claus Laemmerzahl
Prof. Dr. Shin Mineshige
Dr. Monika Moscibrodzka
PD Dr. Volker Perlick
Dr. Daniela Pugliese
Prof. Dr. Luciano Rezzolla
Prof. Dr. Paul Romatschke
Dr. Oldrich Semerak
Dr. Odele Straub

There is no conference fee. The Wilhelm and Else Heraeus-Foundation bears the cost of full-board accommodation for all participants. Up to 75 persons including invited speakers can participate in the seminar. To express your interest in the conference please fill the application form on our website, https://www.we-heraeus-stiftung.de/veranstaltungen/seminare/2019/accretion-in-strong-gravity/application/ or contact us directly.

COST GWverse: Exchange of researchers working on gravitational-wave and black hole physics

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In the context of the European COST Action CA16104 on Gravitational waves, black holes and fundamental physics (GWverse), grants for short term scientific missions (STSMs) are available. We are inviting you to submit proposals for STMSs starting after Nov 1, 2018 and ending before April 30, 2019 (applications outside this timeframe will be discarded).

This call starts on Sep 1 and closes Oct 15, 2018. All proposals will be reviewed and the results will be announced by Nov 1, 2018. The selection committee will take into account the geographical distribution of host and home institution, matching of funds by the host, the scientific proposal and the experience of the applicant (preference is given to Early Career Investigators).

Successful applicants will be expected to join as members of one (or more) of the Action’s Working Groups. STSM recipients should acknowledge the COST Action in any publication or talks, through the use of the COST logo and the statement “The authors would like to acknowledge networking support by the COST Action GWverse CA16104”.

STSMs are a great opportunity for all scientists within the COST Action to exchange visits, nurture collaborations, or develop new ones. Further details are available at the GWverse webpage: https://gwverse.tecnico.ulisboa.pt/stsms/
If you have any question, please contact the STSM Coordinator Andreja Gomboc: andreja.gomboc[at]ung.si

Summer School “The Black Hole Information Loss Paradox”, Bremen, Germany

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The aim of this school is to provide an in-depth overview about recent developments in the field. Starting with a precise formulation of the problem in the first half of the school, we will discuss various solution proposals, with a particular focus on the relation to the BMS-group.

Targeting mainly PhD-students, the material will be covered in form of lectures and discussion sessions.

Related contributions by attendees are also welcome.

Fundamental physics with LISA, Florence, Italy

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Observations of astrophysical systems where gravity is extreme — highly-dynamical and/or non-linearly strong — have the potential to shed light on some of the most profound questions in physics today: from the nature of compact objects to whether Einstein’s theory accurately describes the merger of black holes. The first space-borne detector, LISA, a joint ESA-NASA mission is currently planned to be deployed in 2034, allowing for the first observation of the merger of supermassive black holes and of extreme mass-ratio inspirals. These observations will enable new accurate tests of general relativity, in particular in the strong regime.

We announce the Fundamental Physics with LISA workshop which will take place on November 12-14, 2018 at the Galileo Galilei Institute (Arcetri, Florence, IT). Its goal will be to discuss ways in which we can test General Relativity and learn about fundamental theoretical physics with future LISA observations.

For more information and registration, please visit the conference webpage: http://www.ggi.infn.it/showevent.pl?id=305

In order to encourage interaction and discussion, the workshop will bring together experts in theory, phenomenology, modeling and data analysis, and will have an unusual format. Each day will be centered around one of these facets, and consist of three topical sessions in which discussions will be moderated by a panel of three or four experts. The goal of the workshop is to foster fruitful interactions between different dimensions of LISA science. This will include the following topics:

* Model independent tests versus Model-Specific tests of GR.
* Tests of GR and inferences about physics from the inspiral of supermassive black holes.
* Tests of GR and inferences about physics from the ringdown of supermassive black hole merger.
* Tests of GR and inferences about physics from extreme mass-ratio inspirals.
* Inferences about the nature of supermassive black holes.
* Tests of superradiance and inferences about ultralight boson fields and fuzzy dark matter.
* Exotic compact objects, tests of the horizon, and GW echoes.
* Environmental effects

The number of participants is limited. The registration deadline is *Sepember 1st* or earlier if the capacity of the conference venue is reached. The conference fee (€60) includes lunch tickets for on-site catering.

## PROGRAM ##

DAY 1: THEORETICAL PHYSICS FOUNDATIONS
1A: Black holes
1B: Cosmology
1C: Gravity

DAY 2: INFERENCES
2A: Inferences on exotic objects
2B: Inferences on particle physics
2C: Inferences on theoretical physics

DAY 3: SYSTEMATICS AND DATA ANALYSIS
3A: Massive black-hole binaries: modeling and systematics
3B: Extreme mass-ratio inspirals: modeling and environmental systematics
3C: Data-analysis tools and strategies

## INVITED PANEL SPEAKERS ##
A. Arvanitaki
S. Babak
E. Berti
D. Blas
R. Brito
A. Buonanno *
C. Burrage
C. Caprini
V. Cardoso
K. Chatziioannou
N. Cornish
J. de Boer
P. Ferreira
J. Gair *
S. Giddings
T. Hinderer
S. Hughes
L. Hui
A. Klein
B. Kocsis
C. Palenzuela
A. Raccannelli
T. Sotiriou
L. Stein *
A. Tolley
M. Trodden
M. Van den Meent
M. Vallisneri
A. Vecchio
F. Vernizzi
F. Vidotto
H. Witek
K. Yagi
A. Zimmerman

(* to be confirmed)

######################

Organizers:
Enrico Barausse (Institut d’Astrophysique de Paris),
Thomas Hertog (KU Leuven),
Philippe Jetzer (University of Zurich),
Paolo Pani (Sapienza University of Rome),
Nicolas Yunes (Montana State University)

Support:
– European Research Council Starting Grant DarkGRA-757480 (“Unveiling the dark universe with gravitational waves”).
– COST Action CA16104 “Gravitational waves, black holes and fundamental physics” (GWverse)

Workshop poster (courtesy of Michele Monasta, http://www.michelemonasta.it):

high-res: https://www.dropbox.com/s/de8lxpokwjom6lp/nov_2018.pdf?dl=0
low-res: https://www.dropbox.com/s/ekdpzg6u87gys7c/poster_low_res.pdf?dl=0

COST GWverse: Exchange of researchers working on gravitational-wave and black hole physics

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In the context of the European COST Action CA16104 on Gravitational waves, black holes and fundamental physics (GWverse), grants for short term scientific missions (STSMs) are available. We are inviting you to submit proposals for STMSs starting after May 1, 2018 and ending before Nov 30, 2018 (applications outside this timeframe will be discarded).

This call starts on Feb 15 and closes Mar 30, 2018. All proposals will be reviewed and the results will be announced by Apr 15, 2018.

The selection committee will take into account the geographical distribution of host and home institution, matching of funds by the host, the scientific proposal and the experience of the applicant (preference is given to Early Career Investigators).

Successful applicants will be expected to join as members of one (or more) of the Action’s Working Groups. STSM recipients should acknowledge the COST Action in any publication or talks, through the use of the COST logo and the statement “The authors would like to acknowledge networking support by the COST Action GWverse CA16104”.

STSMs are a great opportunity for all scientists within the COST Action to exchange visits, nurture collaborations, or develop new ones. Further details are available at the GWverse webpage: https://gwverse.tecnico.ulisboa.pt/stsms/
If you have any question, please contact the STSM Coordinator Andreja Gomboc: andreja.gomboc[at]ung.si

COST GWverse: Exchange of researchers working on gravitational-wave and black hole physics

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In the context of the European COST Action CA16104 on Gravitational waves, black holes and fundamental physics (GWverse), grants for short term scientific missions (STSMs) are available. We are inviting you to submit proposals for STMSs starting after Nov 1, 2017 and before April 30, 2018 (applications outside this timeframe will be discarded).

This call starts on Sep 1 and closes Oct 15, 2017. All proposals will be reviewed and the results will be announced by Nov 1, 2017.

STSMs are a great opportunity for all scientists within the COST Action to exchange visits, nurture collaborations, or develop new ones. Further details are available at the GWverse webpage: https://gwverse.tecnico.ulisboa.pt/stsms/
If you have any question, please contact the STSM Coordinator Andreja Gomboc: andreja.gomboc[at]ung.si

Exchange of researchers working on gravitational-wave and black hole physics

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In the context of the European COST Action CA16104 on Gravitational waves, black holes and fundamental physics, grants for short term scientific missions (STSMs) are available. We are inviting you to submit proposals for STMSs starting after July 1 and before November 30, 2017. Applications outside this timeframe will be discarded (a second call will open in September).

This call starts on May 15 and closes June 15, 2017. All proposals will be reviewed and the results will be announced by July 1, 2017.

Short Term Scientific Missions (STSMs) are a great opportunity for all scientists within the COST Action to exchange visits, nurture collaborations, or develop new ones. The COST association defines the STSM as exchange visits between researchers involved in a COST Action, allowing scientists to visit an institution or laboratory in another COST country.

Participants from a participating COST Country or Cooperative State can be hosted at institution in:
– another participating COST Country or Cooperative State,
– another participating COST Country or Cooperative State,
– an approved NNC (Near Neighbour Country) institution,
– an approved IPC (International Partner Country), or
– an approved Specific organization.

Participants from an approved NNC (Near Neighbour Country) institution or an approved European RTD Organization can only be hosted at another participating COST Country or cooperative state.

A European RTD Organisation is any intergovernmental scientific research organisation that is responsible for infrastructures and laboratories whose members are countries, and the majority of which are COST Member Countries or Cooperating State.

STSMs are aimed at fostering collaboration, sharing new techniques and infrastructure that may not be available in other participants’ institutions or laboratories. STSMs are of two types (more on STSM types can be found at: https://gwverse.tecnico.ulisboa.pt/stsms/stsm-types/) and are intended especially for young researchers.

The details of the application procedure can be found at:
https://gwverse.tecnico.ulisboa.pt/stsms/how-to-apply/

For queries, contact the STSM coordinator Andreja Gomboc, andreja.gomboc[at]ung.si

New Frontiers in Gravitational-Wave Astrophysics, Rome, Italy

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The exciting discovery of GW150914 has opened a new era for physics and astrophysics, which is rich of opportunities and challenges. New questions appear, and old questions are posed with renovated strength. This workshop brings together leading experts in gravitational-wave astrophysics, with the aim of discussing new frontiers in this exponentially-growing field, such as formation of black-hole binaries, multiwavelength and multimessenger astronomy, tests of gravity, neutron-star modelling, and equation-of-state extraction from gravitational-wave signals.

There will be few talks per day, three round tables, and plenty of time for discussions. The main themes to be discussed (one per day) are:

– GWs after the first detections
– GWs and neutron-star modelling
– Fundamental physics with GWs
– From ground to space

List of confirmed invited speakers and round-table organizers:

Stanislav Babak (AEI, Germany)
Enrico Barausse (IAP, France)
Andreas Bauswein (HITS, Germany)
Sebastiano Bernuzzi (Parma U., Italy)
Chris Berry (Birmingham U., UK)
Emanuele Berti (Mississippi U., USA)
Vitor Cardoso (IST, Portugal)
Massimo Dotti (Milan U., Italy)
Tania Hinderer (AEI, Germany)
Antoine Klein (IAP, France)
Kostas Kokkotas (Tubingen U., Germany)
Michela Mapelli (Padova U., Italy)
Rosalba Perna (Stony Brook, USA)
Raffaella Schneider (Sapienza U., Italy)
Alberto Sesana (Birmingham U., UK)
Thomas Sotiriou (Nottingham U., UK)
Leo Stein (Caltech, USA)
Alberto Vecchio (Birmingham, UK)
Kent Yagi (Princeton, USA)
Nico Yunes (Montana U., USA)

Since the number of participants is limited, we suggest to register at your earliest convenience.

Looking forward to seeing you in Rome,

Valeria Ferrari, Leonardo Gualtieri, Paolo Pani

Summer school on relativistic accretion, Bremen, Germany

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The Research Training Group (RTG) „Models of Gravity“ organises a summer school on relativistic accretion in September, 26-30, at the University of Bremen, Germany. The full title of the summer school is “Relativistic accretion: theoretical models and their application to observations”, the main foci of the school are the analytical models, current state of observational data from accretion discs around astrophysical black holes and Active Galactic Nuclei (AGN), and the application of the theoretical models for determination of the properties of astrophysical compact objects from observations.

Confirmed Speakers:

Marek A. Abramowicz, N. Copernicus Astronomical Center, Warsaw, Poland.
Wolfgang J. Duschl, Christian-Albrechts-Universitaet, Kiel, Germany.
Vladimir Karas, Charles University, Prague, Czech Republic.
Odele Straub, LUTH, Observatoire de Paris, France

The registration deadline is on August 29. More info can be found by clicking on the “external link” above.

New book: “Introduction to General Relativity, Black Holes and Cosmology”, by Y. Choquet-Bruhat

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Dear Colleagues in General Relativity

To please the kind staff of Oxford University Press, and myself, I send you as propaganda for my last book “Introduction to General Relativity, Black Holes and Cosmology”, whose details can also be found at this website: http://ukcatalogue.oup.com/product/9780199666454.do

With best wishes to all

Yvonne Choquet-Bruhat