Tag Archives: cosmology

Probing the dark sector and general relativity at all scales at CERN, Geneve, Switzerland

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The standard cosmological model, based on the theory of general relativity, has been very successful in explaining the observable properties of the cosmos. This success is achieved at the price of assuming that the energy content of the universe is currently dominated by dark contributions; namely, dark matter and dark energy. Only the large-scale gravitational interaction of these components has been detected so far and their properties remain largely unknown, despite great effort, both theoretical and experimental, that has been made to identify any direct interactions between the dark sector and luminous matter. At present we do not even know if the dark components really exist as a new kind of matter or represent a mirage produced by modifications of the laws of gravity.

The rapid improvement in the quality and quantity of observational data requires the development of more precise and detailed descriptions of the predictions of various models for the dark sector. The prediction of each candidate model must be confronted with data on all scales where the model makes calculable predictions that can be tested observationally or experimentally. Progress in this direction requires a strong cooperative effort from experimentalists, observers and theorists.

The purpose of this TH Institute is to bring together experts in theory, experiments and observations interested in dark matter, dark energy and tests of the laws of gravity. It will provide an opportunity to discuss new ideas to probe the dark sector and general relativity at diverse scales. The topics to discuss include the current consistency tests of the standard cosmological model, the identification of new observable signatures of dark matter and dark energy, experimental/observational methods, tests of gravity, and questions such as to what extent it is possible to discriminate among alternative models. The program will include review talks on the state-of-the art in various fields, as well as contributions on more specific topics. A lot of free time will be left for discussions.

Organisers: Diego Blas, Clare Burrage, Justin Khoury, Diana Lopez Nacir, Paolo Pani, Sergey Sibiryakov, Alfredo Urbano

Postdoc position in numerical relativity/cosmology at Center for Theoretical Physics, Polish Academy of Science

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The Director of the Center for Theoretical Physics invites applications for a postdoctoral position at the CTP PAS, financed from the project “Local relativistic perturbation theory in hydrodynamics and cosmology” No. 2016/22/E/ST9/00578 (SONATA BIS 6) supported by the National Science Center, decision No. DEC-2016/22/E/ST9/00578. The principal investigator is Prof. Mikolaj Korzynski. The position starts on September 1st, 2017.

The position requires a PhD in theoretical or computational physics and experience in numerical relativity, computational hydrodynamics, MHD or compatible field. A background in astrophysics, general relativity or cosmology and experience with the EinsteinToolkit framework would be an advantage.

The group of Mikolaj Korzynski will work on the application of numerical relativity to cosmology, especially the problems of structure formation and the light propagation through spacetime, combining numerics, stochastic and perturbative methods.

The applicants should submit the following documents:
1. cover letter including the statement „I hereby give consent for my personal data included in the job offer to be processed for the purposes of recruitment under the Data Protection Act 1997 (Dz. U. no. 101, item 926)”
2. a scientific CV, including the list of publications and major scientific achievements
3. brief description of research interests
4. copy of the PhD diplomma
5. personal questionnaire form from the CTP PAS webpage via email directly to Mikolaj Korzynski (korzynski[AT]cft.edu.pl). Additionally they should arrange for two letters of recommendation to be sent to the same email address. Applicants expecting to obtain their PhD soon should also include a statement from their supervisors about the scheduled date of their defence.

The deadline for applications has been extended to 1st August 2017. Selected applicants will be invited for an interview. Successful applicant will be employed for the trial period of 12 months, with the possibility of extension for up to 3 further years.

Special Issue “Progress in Cosmology in the Centenary of the 1917 Einstein paper”

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Dear Colleagues,

The first modern cosmological models emerged soon after the discovery of general relativity, putting the study of the Universe as a whole on the firm grounds of an empirically testable, coherent science. In the century since then, cosmology has developed into a precision discipline able to explain the evolution of the Universe in several of its aspects. The goal is under the way, but far than ended. The most stringent open questions remain the nature of dark matter (DM) and of dark energy (DE), and whether General Relativity holds on large cosmological scales.

Of course, many independent observation (anisotropies in CMB, large structure, SNIa data, gravitational lensing, galaxy rotational curves etc.) confirm the necessity of the introduction of these dark components.

However, the existence itself of the most likely DM candidates seem to have been seriously challenged by experiments and or astrophysical observations: e.g. supersymmetric DM and WIMPs by LHC; by LUX, PandaX-II and Xenon100; MACHOs by microlensing. Sterile neutrinos by IceCube and high redshift objects. The properties of the DM in galaxies are presently badly explainable by current theoretical scenarios. At present the nature of DM remains a mystery.

Understanding DE poses an even bigger challenge. Although the cosmological constant may explain the accelerated cosmic expansion, its physical interpretation (as vacuum energy) remains doubtful. Question comes what kind of fields can be responsible for the accelerated cosmic expansion. Several scalar field models of DE induce new type of space-time singularities (e.g. soft singularities). Alternative gravitational theories (e.g. scalar-tensor theories, the emergent gravity model of Verlinde) have been also proposed with the purpose to explain the dark sector.

We invite colleagues to submit papers on the topics:

1: The nature of Dark matter and DE

2: Present/future experiments and observations related to DM, DE and their gravitational effects.

3: Models on DM and DE including the alternative gravitational theories, new fields and their possible interaction with the particles of standard model.

4: Evolution of the Universe, cosmological perturbations, formation of nonlinear structures, first objects.

5: Inflation, initial structure, primordial gravitational waves.

6: Primordial black/white holes, their formation and gravitational waves, their effects on the synthesis of light elements.

7: Anisotropic cosmological models and their perturbations.

8: Exotic singularities, wormholes occurring in cosmological models and in virialized structure.

Dr. Zoltan Keresztes
Prof. Lorenzo Iorio
Prof. Paolo Salucci
Prof. Emmanuel Saridakis
Guest Editors

Inhomogeneous Cosmologies (2nd announcement), Torun, Poland

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During 2-7 July 2017 we are gathering experts in inhomogeneous cosmology for a small workshop of about 30 participants at Nicolaus Copernicus University in Torun, the town where Copernicus was born. We wish to map out the most promising directions for analytical, numerical and observational investigations aimed to take into account both structure formation and cosmological expansion within the constraints of general relativity. A key motivating theme will be to discuss the claim, already investigated in numerous peer-reviewed papers, that “dark energy” as inferred from observations is an artefact of assuming an average Friedmannian expansion. New techniques in numerical relativity are beginning to open new perspectives on these questions. We expect talks on the latest developments, vigorous, constructive debate between “one-percenters” and “order-unity” proponents, and practical hands-on tutorials of the Einstein Toolkit and other free-licensed inhomogeneous cosmology software packages. The workshop sessions will start on the morning of Mon 3 July and continue to late afternoon Fri 7 July.

Due to the limited number of places available, registration by the early registration deadline of 7 April 2017, including a draft abstract, is strongly recommended. If places remain available, late registration will remain open until the late registration deadline of 9 June 2017 – see http://cosmo.torun.pl/CosmoTorun17 for details.

Contact: cosmotorun17 at cosmo.torun.pl

Organising committee: Boud Roukema, Eloisa Bentivegna, Krzysztof Bolejko, Thomas Buchert, Mikolaj Korzynski, Hayley MacPherson, Jan Ostrowski, Sebastian Szybka, David Wiltshire

Topics will include:

* exact cosmological solutions of the Einstein equations
* averaging and backreaction in cosmology
* numerical cosmological relativity
* observational tests

Inhomogeneous Cosmologies (1st announcement), Torun, Poland

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During 2-7 July 2017 we are gathering experts in inhomogeneous cosmology for a small workshop of about 30 participants at Nicolaus Copernicus University in Torun, the town where Copernicus was born. We wish to map out the most promising directions for analytical, numerical and observational investigations aimed to take into account both structure formation and cosmological expansion within the constraints of general relativity. A key motivating theme will be to discuss the claim, already investigated in numerous peer-reviewed papers, that “dark energy” as inferred from observations is an artefact of assuming an average Friedmannian expansion. New techniques in numerical relativity are beginning to open new perspectives on these questions. We expect vigorous, constructive debate between “one-percenters” and “order-unity” proponents, and practical hands-on sessions of free-licensed inhomogeneous cosmology
software packages.

We will post a formal announcement and registration details by early 2017 at http://cosmo.torun.pl/CosmoTorun17.

Contact: cosmotorun17 at cosmo.torun.pl

Organising committee: Boud Roukema, Thomas Buchert, Krzysztof Bolejko, Mikolaj Korzynski, Jan Ostrowski, Sebastian Szybka, David Wiltshire

Special Issue on “Phenomenological Aspects of Quantum Gravity and Modified Theories of Gravity”

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Dear Colleagues,

A Special Issue on “Phenomenological Aspects of Quantum Gravity and Modified Theories of Gravity” will be published in the Journal “Advances in High Energy Physics” in September 2016.

You can find the Call for Papers for this Special Issue at

http://www.hindawi.com/journals/AHEP/si/212894/cfp/

Submission deadline is 6 May 2016.

Cordially Yours,

Lead Guest Editor: Ahmed Farag Ali (Benha University, Egypt)

Guest Editors: Giulia Gubitosi (Imperial College London, London, UK), Mir Faizal (Waterloo University, Waterloo, Canada), Barun Majumder (Montana State University, Bozeman, USA)

9th TRR33 Winter School, Passo del Tonale, Italy

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The school will cover topics relevant to the research subjects of the TRR33 network. The aim is to bring together observation and theory: “Theory for Observers and Observations for Theorists”.

Overview lectures:
David Mota, ITA – University of Oslo

In depth topics:
Observation of Large Scale Structure of the Universe: David Bacon, ICG Portsmouth
Non-linear evolution of Large Scale Structure: Diego Blas, CERN
Science Communication: Anais Rassat, EPFL Lausanne
Dark Matter: Pat Scott, Imperial College London
Beyond the LCDM model: Alessandra Silvestri, Lorentz Institute Leiden

Registration is OPEN: the deadline is 15th October 2015. To register, please visit our website:
http://darkuniverse.uni-hd.de/view/Main/WinterSchool15

Given the large number of applications we strongly suggest an early registration, well in advance of the deadline. Note that we will accept a maximum of 40 participants.

Please email us with any further questions at winter.school[AT]thphys.uni-heidelberg.de

Follow us on our Facebook page
https://www.facebook.com/trr.winter.school
or on twitter using the hashtag #trr33tonale for announcements and reminders

Please check the homepage of the school for more information: http://darkuniverse.uni-hd.de/view/Main/WinterSchool14

See you in Tonale!
the Organizing Committee

Yashar Akrami,
Matteo Costanzi,
Matteo Martinelli,
Matteo Maturi,
Valeria Pettorino,
Georg Wolschin,
Miguel Zumalacárregui

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

New focus issue on string cosmology free to read in CQG

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Dear Colleagues,

We are delighted to announce that the new Classical and Quantum Gravity (CQG) focus issue on string cosmology is now free to read online.

http://iopscience.iop.org/0264-9381/28/20

This issue includes 10 specially invited papers from some of the top researchers in the field.

Guest Edited by Dr Vijay Balasubramanian and Professor Paulo Moniz, the focus issue appraises recent applications of string-theoretic and string-inspired ideas to the cosmos. The articles in this issue also survey a number of potentially promising directions for the future.

With best wishes,

Adam Day
Publisher
Classical and Quantum Gravity
iopscience.org/cqg

Read the latest CQG focus section on inhomogeneous cosmological models and averaging in cosmology

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CQG’s latest focus section on inhomogeneous cosmological models and averaging in cosmology is now available to read on the CQG website:

http://iopscience.iop.org/0264-9381/28/16

The issue was edited by CQG Board Members Lars Andersson and Alan Coley.

The special section focuses on the physical state of the present universe and the problem of going beyond perturbation theory. The following topics are covered:
– a general overview and a discussion of the relevant issues;
– inhomogeneous cosmological models (including non-Copernican models);
– the current observations and physics of the universe and
– averaging and backreaction.

I would like to thank the guest editors and all of the authors and referees of the focus section for their contributions to this excellent issue of Classical and Quantum Gravity.

Yours sincerely

Adam Day
Publisher
Classical and Quantum Gravity