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1st speaker: Francesco De Marco
Title: "Gravitational-wave interferometric detectors and the Virgo experiment"
Abstract: "Although Gravitational-Waves (GWs) were predicted by Einstein within the General Relativity, their first direct detection is dated in 2015, by the LIGO instruments. This milestone discovery unveiled a completely new field with crucial implications in astrophysics, cosmology and fundamental physics.
Today, the worldwide network of GW ground-based detectors, sensitive to the audio frequency band (10 Hz - 10 kHz), is made up of two LIGO antennas in the USA, Virgo in Italy, and KAGRA in Japan. The fourth joint observing run, O4, is now ongoing, and in the previous runs 90 GW events were confirmed.
Detectors like LIGO, Virgo and KAGRA are Michelson interferometers with km-long-baseline Fabry-Perot arms, capable of spotting the displacement caused by the passage of a GW up to 10-21m! In this talk, I will broadly illustrate how a GW interferometric detector works, and what are its main offenders (seismic noise, thermal noise and quantum noise) to GW detection, taking the Virgo detector as an example. Then, I will focus on the quantum noise, and on the strategies to mitigate its impact on the sensitivity of a GW interferometer."
2nd speaker: Francesca Attadio
Title: "Neutron star gravitational waves emission: fundamental physics and search methods"
Abstract: "The first gravitational wave (GW) detection took place in 2015, and it was produced by two coalescing black holes. So far, the only kind of detected GWs signals belongs to the category of transient signals, emitted by two inspiraling compact objects (black holes or neutron stars (NSs)) that last in the detector band, from a fraction of a second to a few tens of seconds.
On the other hand, there are persistent semi-periodic emissions, i.e., continuous waves (CWs), that are produced, for instance, by isolated NSs spinning with an asymmetry.
NSs are characterized by a core density higher than the atomic density, and for this reason, their equation of state is still unknown. Detecting this kind of signal would allow us to better understand how matter behaves in these extreme conditions.
In this presentation, I will introduce you to NSs and their GW emissions. Then, I will describe the existing searches of CWs, and I will focus on long transients, a particular kind of semi-persistent emission that has a duration ranging from several minutes to several hours in the detector sensitivity band. In particular, the focus of my work is on GWs emitted by newly born magnetars, i.e., NSs with strong magnetic fields that cause strong deformations in their shape. In order to retrieve this kind of signal, I developed two machine learning models, and as a last part of my talk, I will describe them."
Federica De Riggi, Giuliano Gustavino, Ambra Mariani, Stefano Palmisano, Lorenzo Pierini