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Article ; Online: New Relativistic Theory for Modified Newtonian Dynamics.

Skordis, Constantinos / Złośnik, Tom

2021 Volume 127, Issue 16, Page(s) 161302

Abstract: We propose a relativistic gravitational theory leading to modified Newtonian dynamics, a paradigm that explains the observed universal galactic acceleration scale and related phenomenology. We discuss phenomenological requirements leading to its ... ...

Abstract	We propose a relativistic gravitational theory leading to modified Newtonian dynamics, a paradigm that explains the observed universal galactic acceleration scale and related phenomenology. We discuss phenomenological requirements leading to its construction and demonstrate its agreement with the observed cosmic microwave background and matter power spectra on linear cosmological scales. We show that its action expanded to second order is free of ghost instabilities and discuss its possible embedding in a more fundamental theory.
Language	English
Publishing date	2021-11-01
Publishing country	United States
Document type	Journal Article
ZDB-ID	208853-8
ISSN	1079-7114 ; 0031-9007
ISSN (online)	1079-7114
ISSN	0031-9007
DOI	10.1103/PhysRevLett.127.161302
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Article: Modifications of gravity.

Skordis, Constantinos

Philosophical transactions. Series A, Mathematical, physical, and engineering sciences

2011 Volume 369, Issue 1957, Page(s) 4962–4975

Abstract: General relativity (GR) is a phenomenologically successful theory that rests on firm foundations, but has not been tested on cosmological scales. The deep mystery of dark energy (and possibly even the requirement of cold dark matter (CDM)) has increased ... ...

Abstract	General relativity (GR) is a phenomenologically successful theory that rests on firm foundations, but has not been tested on cosmological scales. The deep mystery of dark energy (and possibly even the requirement of cold dark matter (CDM)) has increased the need for testing modifications to GR, as the inference of such otherwise undetected fluids depends crucially on the theory of gravity. Here, I discuss a general scheme for constructing consistent and covariant modifications to the Einstein equations. This framework is such that there is a clear connection between the modification and the underlying field content that produces it. I argue that this is mandatory for distinguishing modifications of gravity from conventional fluids. I give a non-trivial example, a simple metric-based modification of the fluctuation equations for which the background is exact ΛCDM, but differs from it in the perturbations. I show how this can be generalized and solved in terms of two arbitrary functions. Finally, I discuss future prospects and directions of research.
Language	English
Publishing date	2011-12-28
Publishing country	England
Document type	Journal Article
ZDB-ID	208381-4
ISSN	1471-2962 ; 1364-503X ; 0080-4614 ; 0264-3820 ; 0264-3952
ISSN (online)	1471-2962
ISSN	1364-503X ; 0080-4614 ; 0264-3820 ; 0264-3952
DOI	10.1098/rsta.2011.0291
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Article ; Online: Dark Matter Equation of State through Cosmic History.

Kopp, Michael / Skordis, Constantinos / Thomas, Daniel B / Ilić, Stéphane

Physical review letters

2018 Volume 120, Issue 22, Page(s) 221102

Abstract: Cold dark matter is a crucial constituent of the current concordance cosmological model. Having a vanishing equation of state (EOS), its energy density scales with the inverse cosmic volume and is thus uniquely described by a single number, its present ... ...

Abstract	Cold dark matter is a crucial constituent of the current concordance cosmological model. Having a vanishing equation of state (EOS), its energy density scales with the inverse cosmic volume and is thus uniquely described by a single number, its present abundance. We test the inverse cosmic volume law for dark matter (DM) by allowing its EOS to vary independently in eight redshift bins in the range z=10^{5} and z=0. We use the latest measurements of the cosmic microwave background radiation from the Planck satellite and supplement them with baryon acoustic oscillation (BAO) data from the 6dF and SDSS-III BOSS surveys and with the Hubble Space Telescope (HST) key project data. We find no evidence for nonzero EOS in any of the eight redshift bins. With Planck data alone, the DM abundance is most strongly constrained around matter-radiation equality ω_{g}^{eq}=0.1193_{-0.0035}^{+0.0036} (95% C.L.), whereas its present-day value is more weakly constrained: ω_{g}^{(0)}=0.16_{-0.10}^{+0.12} (95% C.L.). Adding BAO or HST data does not significantly change the ω_{g}^{eq} constraint, while ω_{g}^{(0)} tightens to 0.160_{-0.065}^{+0.069} (95% C.L.) and 0.124_{-0.067}^{+0.081} (95% C.L.), respectively. Our results constrain for the first time the level of "coldness" required of the DM across various cosmological epochs and show that the DM abundance is strictly positive at all times.
Language	English
Publishing date	2018-06-01
Publishing country	United States
Document type	Journal Article
ZDB-ID	208853-8
ISSN	1079-7114 ; 0031-9007
ISSN (online)	1079-7114
ISSN	0031-9007
DOI	10.1103/PhysRevLett.120.221102
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Article ; Online: Dark Energy after GW170817 Revisited.

Copeland, Edmund J / Kopp, Michael / Padilla, Antonio / Saffin, Paul M / Skordis, Constantinos

Physical review letters

2019 Volume 122, Issue 6, Page(s) 61301

Abstract: We revisit the status of scalar-tensor theories with applications to dark energy in the aftermath of the gravitational wave signal GW170817 and its optical counterpart GRB170817A. At the level of the cosmological background, we identify a class of ... ...

Abstract	We revisit the status of scalar-tensor theories with applications to dark energy in the aftermath of the gravitational wave signal GW170817 and its optical counterpart GRB170817A. At the level of the cosmological background, we identify a class of theories, previously declared unviable in this context, whose anomalous gravitational wave speed is proportional to the scalar equation of motion. As long as the scalar field is assumed not to couple directly to matter, this raises the possibility of compatibility with the gravitational wave data, for any cosmological sources, thanks to the scalar dynamics. This newly "rescued" class of theories includes examples of generalized quintic Galileons from Horndeski theories. Despite the promise of this leading order result, we show that the loophole ultimately fails when we include the effect of large scale inhomogeneities.
Language	English
Publishing date	2019-03-01
Publishing country	United States
Document type	Journal Article
ZDB-ID	208853-8
ISSN	1079-7114 ; 0031-9007
ISSN (online)	1079-7114
ISSN	0031-9007
DOI	10.1103/PhysRevLett.122.061301
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Article: Pseudoscalar perturbations and polarization of the cosmic microwave background.

Pospelov, Maxim / Ritz, Adam / Skordis, Constantinos

Physical review letters

2009 Volume 103, Issue 5, Page(s) 51302

Abstract: We show that models of new particle physics containing massless pseudoscalar fields superweakly coupled to photons can be very efficiently probed with CMB polarization anisotropies. The stochastic pseudoscalar fluctuations generated during inflation ... ...

Abstract	We show that models of new particle physics containing massless pseudoscalar fields superweakly coupled to photons can be very efficiently probed with CMB polarization anisotropies. The stochastic pseudoscalar fluctuations generated during inflation provide a mechanism for converting E-mode polarization to B-mode during photon propagation from the surface of last scattering. The efficiency of this conversion process is controlled by the dimensionless ratio H/(2pif(a)), where H is the Hubble scale during inflation, and f(a)-1 is the strength of the pseudoscalar coupling to photons. The current observational limits on the B mode constrain this ratio to be less than 0.07, which in many models of inflation translates to a sensitivity to f(a) exceeding 10(14) GeV, which surpasses other tests.
Language	English
Publishing date	2009-07-31
Publishing country	United States
Document type	Journal Article
ZDB-ID	208853-8
ISSN	1079-7114 ; 0031-9007
ISSN (online)	1079-7114
ISSN	0031-9007
DOI	10.1103/PhysRevLett.103.051302
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Article ; Online: Cold atoms in space

Alonso, Iván / Alpigiani, Cristiano / Altschul, Brett / Araújo, Henrique / Arduini, Gianluigi / Arlt, Jan / Badurina, Leonardo / Balaž, Antun / Bandarupally, Satvika / Barish, Barry C. / Barone, Michele / Reguzzoni, Mirko / Richaud, Andrea / Riou, Isabelle / Rothacher, Markus / Roura, Albert / Ruschhaupt, Andreas / Sabulsky, Dylan O. / Safronova, Marianna /

Saltas, Ippocratis D. / Bernabeu, Jose / Haehnelt, Martin / Salvi, Leonardo / Sameed, Muhammed / Saurabh, Pandey / Schäffer, Stefan / Schiller, Stephan / Schilling, Manuel / Schkolnik, Vladimir / Schlippert, Dennis / Schmidt, Piet O. / Schnatz, Harald / Hanımeli, Ekim T. / Bertoldi, Andrea / Schneider, Jean / Schneider, Ulrich / Schreck, Florian / Schubert, Christian / Shayeghi, Armin / Sherrill, Nathaniel / Shipsey, Ian / Signorini, Carla / Singh, Rajeev / Hawkins, Leonie / Singh, Yeshpal / Bingham, Robert / Skordis, Constantinos / Smerzi, Augusto / Sopuerta, Carlos F. / Sorrentino, Fiodor

EPJ Quantum Technology

community workshop summary and proposed road-map

2022 Volume 9

Abstract: We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed ... ...

Abstract	We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies. publishedVersion
Keywords	Climate change ; Earth (planet) ; Gravimeters ; Gravitation ; Gravity waves ; Interferometers ; Maps ; Quantum theory ; Atom interferometer ; Cold atoms ; Mass change ; Measurements of ; Prospective applications ; Prospectives ; Roadmap ; Science experiments ; Space community ; Virtual community ; Virtual reality ; 530
Language	English
Publisher	Berlin
Publishing country	de
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Cold atoms in space

EPJ Quantum Technology

community workshop summary and proposed road-map

2022 Volume 9

Abstract	We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies. publishedVersion
Keywords	Climate change ; Earth (planet) ; Gravimeters ; Gravitation ; Gravity waves ; Interferometers ; Maps ; Quantum theory ; Atom interferometer ; Cold atoms ; Mass change ; Measurements of ; Prospective applications ; Prospectives ; Roadmap ; Science experiments ; Space community ; Virtual community ; Virtual reality ; 530
Language	English
Publisher	Berlin
Publishing country	de
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

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Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Cold atoms in space

EPJ Quantum Technology

community workshop summary and proposed road-map

2022 Volume 9

Abstract	We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies. publishedVersion
Keywords	Climate change ; Earth (planet) ; Gravimeters ; Gravitation ; Gravity waves ; Interferometers ; Maps ; Quantum theory ; Atom interferometer ; Cold atoms ; Mass change ; Measurements of ; Prospective applications ; Prospectives ; Roadmap ; Science experiments ; Space community ; Virtual community ; Virtual reality ; 530
Language	English
Publisher	Berlin
Publishing country	de
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Cold atoms in space

EPJ Quantum Technology

community workshop summary and proposed road-map

2022 Volume 9

Abstract	We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies. publishedVersion
Keywords	Climate change ; Earth (planet) ; Gravimeters ; Gravitation ; Gravity waves ; Interferometers ; Maps ; Quantum theory ; Atom interferometer ; Cold atoms ; Mass change ; Measurements of ; Prospective applications ; Prospectives ; Roadmap ; Science experiments ; Space community ; Virtual community ; Virtual reality ; 530
Language	English
Publisher	Berlin
Publishing country	de
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Full text

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Article: Cosmology and fundamental physics with the Euclid satellite.

Amendola, Luca / Appleby, Stephen / Avgoustidis, Anastasios / Bacon, David / Baker, Tessa / Baldi, Marco / Bartolo, Nicola / Blanchard, Alain / Bonvin, Camille / Borgani, Stefano / Branchini, Enzo / Burrage, Clare / Camera, Stefano / Carbone, Carmelita / Casarini, Luciano / Cropper, Mark / de Rham, Claudia / Dietrich, Jörg P / Di Porto, Cinzia /

Durrer, Ruth / Ealet, Anne / Ferreira, Pedro G / Finelli, Fabio / García-Bellido, Juan / Giannantonio, Tommaso / Guzzo, Luigi / Heavens, Alan / Heisenberg, Lavinia / Heymans, Catherine / Hoekstra, Henk / Hollenstein, Lukas / Holmes, Rory / Hwang, Zhiqi / Jahnke, Knud / Kitching, Thomas D / Koivisto, Tomi / Kunz, Martin / La Vacca, Giuseppe / Linder, Eric / March, Marisa / Marra, Valerio / Martins, Carlos / Majerotto, Elisabetta / Markovic, Dida / Marsh, David / Marulli, Federico / Massey, Richard / Mellier, Yannick / Montanari, Francesco / Mota, David F / Nunes, Nelson J / Percival, Will / Pettorino, Valeria / Porciani, Cristiano / Quercellini, Claudia / Read, Justin / Rinaldi, Massimiliano / Sapone, Domenico / Sawicki, Ignacy / Scaramella, Roberto / Skordis, Constantinos / Simpson, Fergus / Taylor, Andy / Thomas, Shaun / Trotta, Roberto / Verde, Licia / Vernizzi, Filippo / Vollmer, Adrian / Wang, Yun / Weller, Jochen / Zlosnik, Tom

Living reviews in relativity

2018 Volume 21, Issue 1, Page(s) 2

Abstract: Euclid is a European Space Agency medium-class mission selected for launch in 2020 within the cosmic vision 2015-2025 program. The main goal of Euclid is to understand the origin of the accelerated expansion of the universe. Euclid will explore the ... ...

Abstract	Euclid is a European Space Agency medium-class mission selected for launch in 2020 within the cosmic vision 2015-2025 program. The main goal of Euclid is to understand the origin of the accelerated expansion of the universe. Euclid will explore the expansion history of the universe and the evolution of cosmic structures by measuring shapes and red-shifts of galaxies as well as the distribution of clusters of galaxies over a large fraction of the sky. Although the main driver for Euclid is the nature of dark energy, Euclid science covers a vast range of topics, from cosmology to galaxy evolution to planetary research. In this review we focus on cosmology and fundamental physics, with a strong emphasis on science beyond the current standard models. We discuss five broad topics: dark energy and modified gravity, dark matter, initial conditions, basic assumptions and questions of methodology in the data analysis. This review has been planned and carried out within Euclid's Theory Working Group and is meant to provide a guide to the scientific themes that will underlie the activity of the group during the preparation of the Euclid mission.
Language	English
Publishing date	2018-04-12
Publishing country	Switzerland
Document type	Journal Article ; Review
ZDB-ID	1416143-6
ISSN	1433-8351
ISSN	1433-8351
DOI	10.1007/s41114-017-0010-3
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