Project acronym Cat-In-hAT
Project Catastrophic Interactions of Binary Stars and the Associated Transients
Researcher (PI) Ondrej PEJCHA
Host Institution (HI) UNIVERZITA KARLOVA
Country Czechia
Call Details Starting Grant (StG), PE9, ERC-2018-STG
Summary "One of the crucial formation channels of compact object binaries, including sources of gravitational waves, critically depends on catastrophic binary interactions accompanied by the loss of mass, angular momentum, and energy (""common envelope"" evolution - CEE). Despite its importance, CEE is perhaps the least understood major phase of binary star evolution and progress in this area is urgently needed to interpret observations from the new facilities (gravitational wave detectors, time-domain surveys).
Recently, the dynamical phase of the CEE has been associated with a class of transient brightenings exhibiting slow expansion velocities and copious formation of dust and molecules (red transients - RT). A number of RT features, especially the long timescale of mass loss, challenge the existing CEE paradigm.
Motivated by RT, I will use a new variant of magnetohydrodynamics to comprehensively examine the 3D evolution of CEE from the moment when the mass loss commences to the remnant phase. I expect to resolve the long timescales observed in RT, characterize binary stability in 3D with detailed microphysics, illuminate the fundamental problem of how is orbital energy used to unbind the common envelope in a regime that was inaccessible before, and break new ground on the amplification of magnetic fields during CEE.
I will establish RT as an entirely new probe of the CEE physics by comparing my detailed theoretical predictions of light curves from different viewing angles, spectra, line profiles, and polarimetric signatures with observations of RT. I will accomplish this by coupling multi-dimensional moving mesh hydrodynamics with radiation, dust formation, and chemical reactions. Finally, I will examine the physical processes in RT remnants on timescales of years to centuries after the outburst to connect RT with the proposed merger products and to identify them in time-domain surveys.
"
Summary
"One of the crucial formation channels of compact object binaries, including sources of gravitational waves, critically depends on catastrophic binary interactions accompanied by the loss of mass, angular momentum, and energy (""common envelope"" evolution - CEE). Despite its importance, CEE is perhaps the least understood major phase of binary star evolution and progress in this area is urgently needed to interpret observations from the new facilities (gravitational wave detectors, time-domain surveys).
Recently, the dynamical phase of the CEE has been associated with a class of transient brightenings exhibiting slow expansion velocities and copious formation of dust and molecules (red transients - RT). A number of RT features, especially the long timescale of mass loss, challenge the existing CEE paradigm.
Motivated by RT, I will use a new variant of magnetohydrodynamics to comprehensively examine the 3D evolution of CEE from the moment when the mass loss commences to the remnant phase. I expect to resolve the long timescales observed in RT, characterize binary stability in 3D with detailed microphysics, illuminate the fundamental problem of how is orbital energy used to unbind the common envelope in a regime that was inaccessible before, and break new ground on the amplification of magnetic fields during CEE.
I will establish RT as an entirely new probe of the CEE physics by comparing my detailed theoretical predictions of light curves from different viewing angles, spectra, line profiles, and polarimetric signatures with observations of RT. I will accomplish this by coupling multi-dimensional moving mesh hydrodynamics with radiation, dust formation, and chemical reactions. Finally, I will examine the physical processes in RT remnants on timescales of years to centuries after the outburst to connect RT with the proposed merger products and to identify them in time-domain surveys.
"
Max ERC Funding
1 243 219 €
Duration
Start date: 2019-01-01, End date: 2023-12-31
Project acronym THEMODS
Project Theories and Models of the Dark Sector: Dark Matter, Dark Energy and Gravity
Researcher (PI) Constantinos Skordis
Host Institution (HI) FYZIKALNI USTAV AV CR V.V.I
Country Czechia
Call Details Consolidator Grant (CoG), PE9, ERC-2013-CoG
Summary Modern cosmology assumes that General Relativity (GR) is the correct description of gravity on large scales. With this assumption and according to current data, the cosmological model needs in addition the existence of a Dark Sector: Dark Matter (DM) and Dark Energy (DE). We know very little about the nature of DM and it is yet to be detected experimentally. The simplest form of DE compatible with the data, a cosmological constant, has a value incompatible with our understanding of Quantum Field Theory. Given that the extrapolation of GR to cosmological scales has not been tested it is possible that the inference of the Dark Sector also needs to be revised.
I propose to (i) determine the nature of DM and DE to a level not achieved before, (ii) test gravity on cosmological scales and (iii) test the screening of new gravitational degrees of freedom in the solar system. The first two goals will require the use of my general framework to parameterize field equations [Skordis, PRD 79, 123527 (2008); Baker, Ferreira & Skordis, PRD 87, 024015 (2013)]. My team will use this framework to construct simple models and observations to place limits on their parameters. We will employ the Cosmic Microwave Background (CMB) observations from ESA's Planck Surveyor and the Atacama Cosmology Telescope. We will determine the sensitivity of the CMB lensing to the properties of DM and theories of gravity. To break possible degeneracies these data will be supplemented with large-scale structure data, weak lensing and red-shift space distortions. We will also perform forecasting for ESA's EUCLID mission which will give us a handle on how well we will constrain GR with cosmology in the future. For the final goal (iii) we will employ the method of [Padilla & Saffin, JHEP 1207, 122 (2012)] to construct a perturbative expansion of theories that exhibit screening, inside the screening radius. We will determine the compatibility of such theories with solar system and other strong-field data.
Summary
Modern cosmology assumes that General Relativity (GR) is the correct description of gravity on large scales. With this assumption and according to current data, the cosmological model needs in addition the existence of a Dark Sector: Dark Matter (DM) and Dark Energy (DE). We know very little about the nature of DM and it is yet to be detected experimentally. The simplest form of DE compatible with the data, a cosmological constant, has a value incompatible with our understanding of Quantum Field Theory. Given that the extrapolation of GR to cosmological scales has not been tested it is possible that the inference of the Dark Sector also needs to be revised.
I propose to (i) determine the nature of DM and DE to a level not achieved before, (ii) test gravity on cosmological scales and (iii) test the screening of new gravitational degrees of freedom in the solar system. The first two goals will require the use of my general framework to parameterize field equations [Skordis, PRD 79, 123527 (2008); Baker, Ferreira & Skordis, PRD 87, 024015 (2013)]. My team will use this framework to construct simple models and observations to place limits on their parameters. We will employ the Cosmic Microwave Background (CMB) observations from ESA's Planck Surveyor and the Atacama Cosmology Telescope. We will determine the sensitivity of the CMB lensing to the properties of DM and theories of gravity. To break possible degeneracies these data will be supplemented with large-scale structure data, weak lensing and red-shift space distortions. We will also perform forecasting for ESA's EUCLID mission which will give us a handle on how well we will constrain GR with cosmology in the future. For the final goal (iii) we will employ the method of [Padilla & Saffin, JHEP 1207, 122 (2012)] to construct a perturbative expansion of theories that exhibit screening, inside the screening radius. We will determine the compatibility of such theories with solar system and other strong-field data.
Max ERC Funding
1 150 691 €
Duration
Start date: 2014-08-01, End date: 2019-07-31
