Theoretical cosmology meeting

03Feb2017 12:00 - 18:00

Event

Speakers: J. Magueijo (Imperial College) and J. Garcia-Bellido (IFT Madrid). Location: Leiden

Programme

14:00 - 15:00 J. Magueijo (Imperial College)

The critical geometry of a thermal Big Bang 

15:00 - 15:30 Coffee

15:30 - 16:30 J. Garcia-Bellido (IFT Madrid)

Gravitational Waves from Primordial Black Holes as Dark Matter

16:30- 17:30 Borrel 

Abstracts

J. Magueijo (Imperial College)

The critical geometry of a thermal Big Bang 

Abstract: We explore the space of scalar-tensor theories containing two non-conformal metrics, and find a discontinuity pointing to a “critical” cosmological solution. Due to the different maximal speeds of propagation for matter and gravity, the cosmological fluctuations start off inside the horizon even without inflation, and will more naturally have a thermal origin (since there is never vacuum domination). The critical model makes an unambiguous, non-tuned prediction for the spectral index of the scalar fluctuations: ns = 0.96478(64). Considering also that no gravitational waves are produced, we have unveiled the most predictive model on offer. The model has a simple geometrical interpretation as a probe 3-brane embedded in an EAdS2 × E3 geometry.

J. Garcia-Bellido (IFT Madrid) 

Gravitational Waves from Primordial Black Holes as Dark Matter

Abstract: 20 years ago, we predicted that primordial black holes (PBH) would form via the gravitational collapse of matter associated with peaks in the spectrum of matter fluctuations, and that they could constitute all of the dark matter today. Last year, we predicted the mass distribution of PBH, which peaks at 50 Msun and whose tails could be responsible for the seeds of galaxies. LIGO has recently detected gravitational waves from the inspiraling of three black hole binaries. We propose that LIGO has actually detected dark matter in the form of PBH, and predict that within 10 years, an array of GW detectors (i.e. LIGO, VIRGO, KAGRA, INDIGO, etc.) could be used to determine the mass and spin distribution of PBH dark matter. Furthermore, the stochastic GW background from inspiralling PBH will potentially be detected by LISA and PTA, and will open a new window into the Early Universe.

Location

Casimir room (Oort building, Room 276, the Institute Lorentz coffee room), Niels Bohrweg 2, Leiden

 

source: THC@NL

Published by  D-ITP