Theoretical Cosmology meetings
To actively encourage the field of theoretical cosmology and to set an informal stage for the exchange of ideas, the Dutch theoretical cosmology community organizes Friday afternoon meetings approximately 6 times a year — usually on the first Friday of the month. The meetings typically start in the afternoon with a main speaker, followed by a short break to continue with another seminar or journal club discussion on some topic of current interest. We end the afternoon with drinks. The supporting institutes in Leiden, Amsterdam, Groningen, Utrecht where recently joined by the strings and cosmology group in Leuven and take turns in hosting the event.
- This event has passed.
Leiden Spring 2016
04/03/2016 @ 12:30 - 18:00
12.30-14:00 Lunch (Canteen, Oort building)
To simplify things, we will have lunch in the canteen of the Oort building including the two speakers.
So we can all meet there. Or shortly before in room 276 of Oort building (the coffee room, where we will be having an informal meeting with David Reitze).
We study the realization of slow-roll inflation in N=1 supergravities
with a single chiral field. If there is only one flat direction in
field space, it is possible to derive a single-field effective field
theory (EFT) parametrized by the sound speed cs at which curvature
perturbations propagate during inflation. The value of cs is
determined by the rate of bend of the inflationary trajectory
resulting from the shape of the F-term potential. We show that cs must
respect an inequality that involves the curvature tensor of the
K”ahler manifold defining the class of supergravity, as well as the
ratio between the mass of fluctuations ortogonal to the inflationary
trajectory and the Hubble expansion rate. Because in order to have a
reliable EFT this ratio must be large, we find that the inequality
implies that cs≃1. As a consequence, EFT’s of inflation derived from
N=1 supergravities cannot differ drastically from canonical single
field inflation (cs=1), and non-Gaussianity must be suppressed unless
other degrees of freedom play a role during inflation. Conversely, if
large non-Gaussianity is observed, supergravity models of inflation
will be disfavored. [Based on arxiv 1601.05457]
16.00: Joan van der Waals colloquium (Room C1, Gorlaeus building)
Executive Director, LIGO Laboratory
On September 14, 2015, scientists from the LIGO Scientific
Collaboration and the Virgo Collaboration observed the collision and
fusion of the two black holes by directly measuring the gravitational
waves emitted during the collision using the LIGO detectors. This
detection comes 100 years after Einstein developed his revolutionary
general theory of relativity that predicted their existence, and 50
years after scientists began searching for them.
This discovery has truly profound implications. Gravitational waves
provide unique information on the most energetic astrophysical events,
revealing unique insights into the nature of gravity, matter, space,
and time.
We have opened a new window on the cosmos. I will talk about how we
made the detection and discuss how gravitational astronomy promises to
change our understanding of universe.
Borrel