Cover Page
The handle http://hdl.handle.net/1887/78122 holds various files of this Leiden University dissertation.
Author: Vardanyan, V.
Propositions accompanying the dissertation "Aspects of Cosmic Acceleration"
1. Inflationary α-attractor models can be extended to provide a unified framework for cosmic inflation and dark energy. In these extensions there exist powerful "consistency relations" between the inflationary and dark-energy observables [Chapter 2].
2. Gravitational-wave observations are able to severely constrain some alternative theories to General Relativity. In the case of the doubly-coupled bimetric theory of gravity these observations pinpoint to an interesting class of solutions, known as proportional background solutions [Chapter 3].
3. Investigating the vast variety of massive-gravity extensions to General Relativity is a well-motivated and timely research direction. For instance, cosmological observations and the requirement of perturbative stability impose strong constraints on the parameter space of Mimetic Massive Gravity [Chapter 4].
4. Density profiles of dark matter halos are sensitive to various microphysical details, including the theory of gravity. The so-called Splashback is an interesting feature of these profiles, and its location can be very sensitive to details of the screening mechanisms in modified gravity [Chapter 5].
5. Tests of gravity are entering a doubly-interesting epoch. We are witnessing not only a considerable improvement of the observational data, but also a wealth of complementary novel probes ranging from laboratory tests to new types of cosmological observations.
Baker et.al., arXiv:1908.03430 [astro-ph.CO], for a recent summary.
6. Gravitational waves are opening up a new window to the universe. This is achieved not only through the detection of gravitational waves from distinct, resolved sources, but also via the faint (and yet undetected) anisotropic gravitational-wave background originating from unresolvable astrophysical sources in the universe.
Cusin et.al., Phys.Rev. D 96 (2017) 103019.
7. As the so-called H0 tension gains statistical significance, it begins to pose a serious problem for the ΛCDM
model of cosmology. This tension can be considered as a guideline for exploring beyond-ΛCDM scenarios. Verde et.al, arXiv:1907.10625 [astro-ph.CO].
8. The De Sitter Swampland conjectures, if proven to be true in their strongest form, will pose a challenge for constructing observationally viable models of late-universe cosmic acceleration in string theory.
Obied et.al., arXiv:1806.08362 [hep-th], Akrami et.al., Fortsch.Phys. 67 (2019), 1800075.
9. Cosmology is the broadest and most cross-disciplinary field in physics.
10. Researchers in fundamental sciences should be more actively involved in influencing governmental science policies.
11. Having an agreeable office-mate is an essential part of doing PhD research.
