Periodic Reporting for period 1 - GalaxyDance (Dance of galaxies: testing General Relativity and alternatives using galaxy velocity fields)
Reporting period: 2017-09-04 to 2019-09-03
One of the most fundamental problems of contemporary physics is to explain the physical mechanism behind the observed acceleration of the Universal expansion. The LCDM model employs General Relativity (GR) as the underlying theory of gravity, assumed to be valid on all scales. When interpreted within GR, the universal acceleration is caused by a cosmological constant of a very small value. However, this is very difficult to reconcile with particle physics which predicts it to be some 50 orders of magnitude larger than measured. This mismatch has motivated vivid research activity on the cosmological constant problem. On the theoretical side we have in particular seen the emergence of a plethora of modified gravity (MG) theories, which attribute the observed acceleration to a breakdown of GR on cosmological scales. On the observational side, many new ambitious astronomical surveys are being deployed to both test GR and Dark Energy and to study the cosmic acceleration in exquisite details; a prime example is the flagship European space mission Euclid to be launched already in 2021. Testing GR and verifying its validity on large scales is one of the main goals of the 21st-century extragalactic astronomy. However, so far Einstein’s theory of gravity has only been rigorously probed on astrophysical scales, i.e. in the Solar System or for compact objects like black holes and neutron stars. At present, by using Einstein's theory to describe the whole observable Universe we make an extrapolation of 15 orders of magnitude.
“GalaxyDance” takes at heart the urgent need to design possible tests of Dark Energy and Dark Matter models. To envisage such tests a new state-of-the-art computer simulations of standard and alternative cosmological models are used. Such “virtual universes” created with a help of supercomputers are then a subject of a high-level analysis that indicate which properties of the observed Universe can be used to test different models and to shed the light on the dark side of the Cosmos.
Another important finding consisted in recognising that dedicated artificial galaxy catalogues need to be created in a more consistent with current observations fashion in order to faithfully represent any potential for discovering new gravitational clustering physics. Once a specific anchoring data from astronomical galaxy survey is used many previously considered promising observables turned-out to be less suited for performing tests of theory of gravity. The researchers however, had found that a specific clustering statistics of higher-order nature can be constructed for galaxy data. Such clustering statistics should contain a strong signal of modified physics even when the artificial galaxy catalogue had been designed to met additional observational constraints. This show a great promise to foster new exciting and stringent tests of gravity to be conducted with the astronomical data incoming from the new grand surveys.
• The development and build-up of the field of computational cosmology in Poland and in Central Europe. The developments and research in this field is ultimately connected with reduction, analysis and interpretation of all BigData stemming from extra-galactic astronomy observations. Thanks to “GalaxyDance”, the fellow of this action was able to create, a new, internationally competitive research group in computational cosmology. Developing and tightening the links of country’s local astronomical research community with the European and global one.
• Increase of the potential and perspective of active participation of local research and industry in planned ESA and ESO missions. The potential to actively participate in numerous missions and campaigns of ESA & ESO by Polish researchers and local industry companies is yet to be fully exploited. The research and development task that were conducted in “GalaxyDance” will contribute towards increasing chances of Poland’s participation on technological and science levels in these projects. This undoubtedly contribute towards increasing innovative potential of Polish and European Science and Economy in the global level.
• Increase of awareness and knowledge of the General Public in the are of modern cosmology. The ambitious goals of this proposal resulted in several research papers published in high impact factor journals. The fellow had invested a major effort to educate the general audience of the importance and merit of “GalaxyDance” and modern cosmology in general research topics and results. This was achieved not only via use of modern communications channels like the social media (YouTube and Facebook pages), but also using using more traditional media like radio, TV and public science festivals The long-term impact on society that popularisation of science, and especially on research and discoveries made by local scientists, is well recognized and valued in all modern developed countries. This offers excellent training giving fundamental research flagship role in attracting children to science and technology.