Consortium-related discussion on:
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- "SGWB characterization" WP
I will revisit the most important cosmological and astrophysical constraints on the fraction of dark matter (DM) in primordial black holes (PBHs). I consider a variety of production mechanisms and mass functions for PBHs and discuss whether they can constitute the observed DM abundance or not. I also discuss how one can constrain the physics of the early Universe with the constraints on PBHs.
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- Production of SGWB
I will give a brief introduction to the theory of cosmic strings in the early universe and discuss recent progress in our understanding of the evolution of a cosmic string network using Nambu-Goto simulations. I will then discuss the production of gravitational waves from this network and how this leads to a prediction of an stochastic background of gravitational waves covering a wide range of...
We discuss an analytic approach to solving the problem of the gravitational self-interaction of cosmic strings. We demonstrate this approach on a simple toy model of string loops, and discuss how it might be applied to a string loop network.
Cosmic strings are one-dimensional topological defects which may have been generated in the early Universe. LISA will be an excellent probe of cosmic strings as they emit strong gravitational wave bursts. In my talk, I will review the possibility of probing cosmic strings through detection of rare bursts as well as of a stochastic background, which consists of many overlapped bursts. I will...
Cosmic superstrings of string theory differ from conventional cosmic strings of field theory, influencing the expectations for searches for relics from inflation. The universe's average density of cosmic superstrings can easily exceed that of conventional cosmic strings having the same tension by two or more orders of magnitude. The cosmological behavior of the remnant superstring loops is...
In modified gravity the propagation of gravitational waves is in general different from that in general relativity. As a result, the luminosity distance for GWs can differ from that for electromagnetic signals, and is affected both by the dark energy equation of state and by a function describing modified propagation. The effect of modified propagation in general dominates over the...
We briefly review whether and how some theories of quantum gravity could be tested by LISA, either with stand-alone data or in combination with other observations. In particular, we focus our attention on string theory, loop quantum gravity, asymptotic safety, nonlocal quantum gravity, and multifractional spacetimes. We stress the importance and meaning of following top-down approaches (from a...
Chern-Simons gravity is a modified gravity theory where a term like $f(\phi) C \tilde C$ is added to the Einstein-Hilbert Lagrangian. Here $C$ symbolically labels the Weyl tensor, the trace-less part of the Riemann tensor. In this context $\phi$ can be both a scalar or a pseudo-scalar field and $f(\phi)$ is a generic scalar coupling function. Phenomenologically, it is interesting to study the...
We show that the present dark matter abundance can be accounted for by an oscillating scalar field that acquires both mass and a non-zero expectation value from interactions with the Higgs field. The dark matter scalar field can be sufficiently heavy during inflation, due to a non-minimal coupling to gravity, so as to avoid the generation of large isocurvature modes in the CMB anisotropies...
I will review mechanisms of production of matter during inflation that will in its turn lead to the generation of gravitational waves. These gravitational waves can be of relevance both for the phenomenology of the CMB and for gravitational interferometers.
For the current central values of the Higgs and top masses, the Standard Model Higgs potential develops an instability at a scale of the order of $10^{11}$ GeV. We show that a cosmological signature of such instability could be the generation of gravitational waves detectable by LISA and we characterize their two- and three-point correlators.
