Transcript The detection of gravitational waves

The detection of gravitational waves
Workshop
Aula Magna del Dipartimento di Fisica e Astronomia
14 aprile 2016
On February 11th, 2016, the LIGO and Virgo Collaborations announced the first direct detection of gravitational waves
(GWs) from the cosmos and the first observation of a coalescence event of two stellar origin black holes. A key
prediction of General Relativity has been confirmed, a century after Einstein's paper on GWs. In this workshop we report
on the key technology that made this discovery possible and describe GW150914, the first source of the GW universe. We
first introduce the notion of GWs as predicted by Einstein, and illustrate the working principles and realization of the
advanced detectors. Interferometry has achieved the sensitivity level and reliability sufficient to detect the tiny
perturbations of the space-time induced by a collision of black holes.
We the describe the signal and how signals in general could extracted from the noise, and collect convincing evidence
on their nature.
GWs carry precious information on the masses and spins of the merging compact objects, and the search of an
electromagnetic (EM) counterpart is key to further deepen the knowledge of the astrophysical environment and of the
source itself. The next challenge will be to associate the merger of two neutron stars with a Gamma Ray Bursts, and to
discover whether a black hole coalescence has an EM signal associated. Therefore, the quest for GW detection is part of
a worldwide effort, which involves EM facilities and particle detectors. We review on the astrophysical implications of
GW150914 and shortly describe other sources that can be detected in the high frequency window of LIGO and Virgo.
Finally we portrait the astrophysical sources target of the forthcoming eLISA mission. eLISA is an interferometer in
space designed to detect, at lower frequencies (around a mHz), the signal from coalescing supermassive black holes in
merging galaxies, and other sources, including the possible presence of a cosmological background. A short note will
follow on the Pulsar Timing Array experiment.
Programme:
14:30
The detectors which discovered GW
Giovanni Losurdo (INFN Firenze)
15:15
The first observation of a binary black hole merger
Andrea Viceré (Università degli Studi di Urbino & INFN Firenze)
15:50
Astrophysical interpretation, and the multi-messenger context
Marica Branchesi (Università degli Studi di Urbino & INFN Firenze)
16:25
The present and future in space: LISA pathfinder, eLISA and its sources
Monica Colpi (Università degli Studi di Milano-Bicocca & INFN Milano-Bicocca)