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Your search keyword '"Astrophysics - Cosmology and Nongalactic Astrophysics"' showing total 4 results
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4 results on '"Astrophysics - Cosmology and Nongalactic Astrophysics"'

1. Cosmological acceleration

Author

Blinnikov, Sergei I. and Dolgov, Alexander D.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

An overview is given of the current status of the theory and observations of the acceleration of the expansion of the observable part of the Universe. Contents 1. Historical Introduction 2. Friedmann equations and cosmological acceleration 3. Vacuum energy problem 4. Data in favor of cosmological acceleration 5.Data on supernovae and baryon acoustic oscillations 5.1 Cosmography primer: distances in the Universe; 5.2 Photometric distance; 5.3 Cosmic distance ladder; 5.4 Variety of type-Ia supernovae light curves and their usage in cosmography; 5.5 Baryon acoustic oscillations (BAOs); 5.6 BAOs in the correlation function of galaxies; 5.7 Summary of results on supernovae combined with BAOs; 5.8 Systematics and dependence on z; 5.9 Supernovae as primary distance indicators; 5.10 Merging of neutron stars and the standard siren method 6. Dark energy 7. Modified gravity 8.Conclusion 9.Appendices 9.1 Derivation of the Friedmann equations; 9.2 Cosmological parameters; 9.3 Scalar field, Comment: 81 pages, 11 figures, in Russian, close to the published version with typos corrected. English DOI:10.3367/UFNe.2018.10.038469

Published
2020
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2. Cosmological models of dark energy: theory and observations

Author

Avsajanishvili, Olga

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We investigated the evolution of the background expansion and the growth rate of the matter density fluctuations in the scalar field $\phi$CDM Ratra-Peebles model. We constrained the model parameter $\alpha$ and the matter density parameter $\Omega_{\rm m}$ using the recent measurements of the growth rate of the matter density fluctuations and baryon acoustic oscillation peak position. In addition, we studied a number of the $\phi$CDM scalar field models in order to determine whether or not it would be possible to discriminate them from the $\Lambda$CDM model using predicted data for the future Dark Energy Spectroscopic Instrument (DESI) observations. For this purpose, we carried out the statistical Bayesian analysis, and computed Bayes coefficients, as well as Akaike and Bayesian information criteria. We found that projected DESI results could provide compelling when comparing most $\phi$CDM models with the $\Lambda$CDM model. We also conducted the MCMC analysis and obtained the constraints on the parameters of the scalar field models, comparing the observational data for: the universe expansion rate, the angular diameter distance and the growth rate function, with the corresponding data generated for the $\Lambda$CDM model. We investigated how well the Chevallier-Polarsky-Linder (CPL) parametrization approximates the various scalar field models. We determined the location of scalar field model in the phase space of the CPL parameters., Comment: PhD thesis (in Russian), 192 pages, 35 figures, 7 tables, comments are welcome

Published
2019

3. RadioAstron -- a Telescope with a Size of 300 000 km: Main Parameters and First Observational Results

Author

N. S. Kardashev, V. V. Khartov, V. V. Abramov, V. Yu. Avdeev, A. V. Alakoz, Yu. A. Aleksandrov, S. Ananthakrishnan, V. V. Andreyanov, A. S. Andrianov, N. M. Antonov, M. I. Artyukhov, M. Yu. Arkhipov, W. Baan, N. G. Babakin, V. E. Babyshkin, N. Bartel’, K. G. Belousov, A. A. Belyaev, J. J. Berulis, B. F. Burke, A. V. Biryukov, A. E. Bubnov, M. S. Burgin, G. Busca, A. A. Bykadorov, V. S. Bychkova, V. I. Vasil’kov, K. J. Wellington, I. S. Vinogradov, R. Wietfeldt, P. A. Voitsik, A. S. Gvamichava, I. A. Girin, L. I. Gurvits, R. D. Dagkesamanskii, L. D’Addario, G. Giovannini, D. L. Jauncey, P. E. Dewdney, A. A. D’yakov, V. E. Zharov, V. I. Zhuravlev, G. S. Zaslavskii, M. V. Zakhvatkin, A. N. Zinov’ev, Yu. Ilinen, A. V. Ipatov, B. Z. Kanevskii, I. A. Knorin, J. L. Casse, K. I. Kellermann, Yu. A. Kovalev, Yu. Yu. Kovalev, A. V. Kovalenko, B. L. Kogan, R. V. Komaev, A. A. Konovalenko, G. D. Kopelyanskii, Yu. A. Korneev, V. I. Kostenko, A. N. Kotik, B. B. Kreisman, A. Yu. Kukushkin, V. F. Kulishenko, D. N. Cooper, A. M. Kut’kin, W. H. Cannon, M. G. Larionov, M. M. Lisakov, L. N. Litvinenko, S. F. Likhachev, L. N. Likhacheva, A. P. Lobanov, S. V. Logvinenko, G. Langston, K. McCracken, S. Yu. Medvedev, M. V. Melekhin, A. V. Menderov, D. W. Murphy, T. A. Mizyakina, Yu. V. Mozgovoi, N. Ya. Nikolaev, B. S. Novikov, I. D. Novikov, V. V. Oreshko, Yu. K. Pavlenko, I. N. Pashchenko, Yu. N. Ponomarev, M. V. Popov, A. Pravin-Kumar, R. A. Preston, V. N. Pyshnov, I. A. Rakhimov, V. M. Rozhkov, J. D. Romney, P. Rocha, V. A. Rudakov, A. Räisänen, S. V. Sazankov, B. A. Sakharov, S. K. Semenov, V. A. Serebrennikov, R. T. Schilizzi, D. P. Skulachev, V. I. Slysh, A. I. Smirnov, J. G. Smith, V. A. Soglasnov, K. V. Sokolovskii, L. H. Sondaar, V. A. Stepan’yants, M. S. Turygin, S. Yu. Turygin, A. G. Tuchin, S. Urpo, S. D. Fedorchuk, A. M. Finkel’shtein, E. B. Fomalont, I. Fejes, A. N. Fomina, Yu. B. Khapin, G. S. Tsarevskii, J. A. Zensus, A. A. Chuprikov, M. V. Shatskaya, N. Ya. Shapirovskaya, A. I. Sheikhet, A. E. Shirshakov, A. Schmidt, L. A. Shnyreva, V. V. Shpilevskii, R. D. Ekers, and V. E. Yakimov

Subjects
Active galactic nucleus, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, law.invention, Radio telescope, Telescope, Astrophysical jet, law, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, Physics, Supermassive black hole, Star formation, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Planetary system, Astrophysics - Astrophysics of Galaxies, Galaxy, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The Russian Academy of Sciences and Federal Space Agency, together with the participation of many international organizations, worked toward the launch of the RadioAstron orbiting space observatory with its onboard 10-m reflector radio telescope from the Baikonur cosmodrome on July 18, 2011. Together with some of the largest ground-based radio telescopes and a set of stations for tracking, collecting, and reducing the data obtained, this space radio telescope forms a multi-antenna ground-space radio interferometer with extremely long baselines, making it possible for the first time to study various objects in the Universe with angular resolutions a million times better than is possible with the human eye. The project is targeted at systematic studies of compact radio-emitting sources and their dynamics. Objects to be studied include supermassive black holes, accretion disks, and relativistic jets in active galactic nuclei, stellar-mass black holes, neutron stars and hypothetical quark stars, regions of formation of stars and planetary systems in our and other galaxies, interplanetary and interstellar plasma, and the gravitational field of the Earth. The results of ground-based and inflight tests of the space radio telescope carried out in both autonomous and ground-space interferometric regimes are reported. The derived characteristics are in agreement with the main requirements of the project. The astrophysical science program has begun., 54 pages, 11 figures; published by Astronomicheskij Zhurnal (in Russian) and Astronomy Reports (in English)

Published
2013

4. Thermodynamics and kinetics of elementary particles in cosmology

Author

Dolgov, A. D.

Subjects
High Energy Physics - Phenomenology, Cosmology and Nongalactic Astrophysics (astro-ph.CO), High Energy Physics - Phenomenology (hep-ph), FOS: Physical sciences, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Several lectures for non-experts on equilibrium and non-equilibrium kinetics in expanding universe are presented. An establishment of thermal equilibrium in the ealry universe as well as mechanisms leading to deviations from the equilibrium are discussed. In the first lecture an elementary introduction to cosmology is presented. Next, kinetic equation in Friedman-Robertson-Walker mertric is considered. Properties of its solutions for different types of particles, in particular, for photons of cosmic microwave background radiation, neutrinos, and massive particles, which could be cold dark matter ones, are analyzed. It is shown, in particular, that despite being massless, neutrinos noticeably deviate from equilibrium. Next the modification of the detailed balance condition in the case of broken T-invariance is discussed and it is shown that the standard equilibrium distribution functions remain unchanged. Possible modification of the standard kinetics in the case of broken CPT and applications to baryogenesis are considered., 24 pages, in Russian, Lectures presented at the Summer School "Fundamental Interactions" organized by D. Zumin Foundation "Dinastiya"; Protvino, Russia, August, 2012

Published
2013

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