87th ICREA BREAKFAST COLLOQUIUM - Observing the dark side of the Universe with gravitational lensing and gravitational waves

Speakers: ICREA Research Professors Ramon Miquel and Mario Martínez (both from IFAE)

When: 11th of June 2019, 9:00h

Where: Hotel Catalonia Plaça Catalunya, Bergara, 11, 08002 Barcelona

Abstracts:

Ramon Miquel

There is overwhelming evidence that most of the matter in the universe is in a "dark" form that neither emits nor blocks light, and is therefore invisible to even the largest telescopes. While the detailed nature of this "dark matter" remains unknown, its gravitational interactions can be used to detect it and study its spatial distribution as a function of cosmic time. Particularly relevant is the so-called "weak gravitational lensing" effect, in which the observed shapes of distant galaxies are slightly modified by the gravitational pull of the masses between them and us.

Since 2013, the DES Collaboration has been surveying an entire octant of the sky, measuring the position on the sky, redshift and shape of 300 million galaxies, together with thousands of galaxy clusters and supernovae. Using the dataset from its first season of observations, DES has measured the shapes of about 35 million galaxies, from which it has produced the largest (dark) matter map to date. Combining this with other DES measurements, DES has achieved an unprecedented precision in the determination of the cosmological parameters governing the growth of structures in the universe. The talk will present these measurements and discuss their relevance in shaping our understanding of the origin, evolution and ultimate fate of our universe.

Mario Martínez

The detection of Gravitational Waves from a black hole binary merger by the LIGO interferometer in 2016, confirming a 100-year old Einstein prediction, represented the beginning of a new era in the exploration of the universe. Shortly thereafter, the addition of the Virgo antenna into the network led to the detection of the first neutron star binary merger, which could then be followed in electromagnetic signals, and thus represented the beginning of multi-messenger astronomy. This single observation led to stringent tests of models for Gravity beyond General Relativity, an independent measurement of the universe expansion rate, and the observation of a so-called kilonovae and the ratification of the astrophysical origin of heavy elements in the periodic table. The LIGO and Virgo interferometers resume operations in String 2019 with improved sensitivity, thus promising new discoveries.

The talk will describe the sources of Gravitational Waves, their detection using extremely precise interferometry, the prospects of the experiments in the following years, and how Gravitation Waves are considered unique windows towards the understanding of Gravity at extreme conditions and the very early universe 13.8 billion years ago.

The ICREA colloquia are a great way to learn about remote fields of research from our best experts. We usually have two speakers, who offer their opinions on the same subject from very different angles. They are open to all ICREAs and their guests.