Main Page
This page serves mostly to present the work of the GSSI gravitational-wave group, which means that its content is strongly focused on the group's activities. We do not intend to provide a generic overview of research topics in this field.
Contents
GSSI Gravity Group
Members
Einstein Telescope
The Einstein Telescope (ET) is a proposed next-generation, gravitational-wave (GW) detector in a new underground facility [ET home page]. It will achieve a sensitivity to GWs vastly superior to the current GW detectors LIGO and Virgo. Key factors are the increased baseline of 10km (compared to 3km for the Virgo detector and 4km for the LIGO detectors), increased light power inside the arms, and cryogenics to cool the suspended test masses and the suspension fibers. Furthermore, ET will extend the observation band to lower frequencies, i.e., down to a few Hertz. Essential for this purpose is to construct the detector at an extremely quiet site since noise produced in ET by the environment contributes most strongly at low frequencies. In Europe, such a low-noise environment can only be guaranteed at remote underground sites. This also impacts the detector configuration. It was found that a so-called xylophone configuration of ET with two separate interferometers, one optimized for low frequencies, one for high frequencies, is the best way to realize an observation band that ranges from a few Hertz to a few thousand Hertz [ET detector configuration].
The widening of the observation band together with the sensitivity improvements will make it possible to study GW sources over cosmological scales and at the same time study the properties of GW sources with unprecedented accuracy [ET science case]. It will be possible to explore phenomena of extreme gravity, matter under extreme conditions, observe the complete population of stellar-mass binary black holes, and carry out combined, multi-messenger observations with telescopes. The hope is that ET will be part of a global network of GW detectors including other next-generation detectors like the proposed US detectors Voyager [Voyager]and Cosmic Explorer [Cosmic Explorer], which will further increase the science that can be done through GW observations [3G science case].
At the Gran Sasso Science Institute, the GW group is involved in experimental and design studies of the instrument, in the development of data-analysis techniques as well as the evaluation of the science capacity of the ET detector configuration, and the group also develops the science case in combination with (potential or certain) future EM facilities like THESEUS [THESEUS], E-ELT [E-ELT], or VRO (formerly LSST) [VRO].
Site Characterization and Evaluation
Site-evaluation parameters
Results from Sardinia
GW Data Analysis
Advanced LIGO and Virgo detectors started the first scientific run on September 2015, and just completed the O3 run. On the first two runs, a total of 11 GW signals have been detected: O1-O2 Catalog paper. They were all coming from the coalescence and merging of compact objects, 10 from Black Hole Binaries (BBH) and 1 from a Binary Neutron Star (BNS)
The BNS arrived on is the first case of Multi-Messenger Astronomy between GW and EM.
Parameter estimation of compact binaries
Cosmology: Probing the Early Universe
Searches for generic GW transients
Instrument Science
Environmental Noise
Detector Control
Earthquake early warning with gravitational sensors
Quantum noise modeling and detector configurations
Thermal noise in GW detectors
Electromagnetic Counterpart of Gravitational Waves
Multimessenger Search of Core-Collapse Supernovae
In this research topic, we focus on multimessenger analysis to hunt for core-collapse supernovae (CCSNe) via low-energy neutrino (LEN, ~MeV energy) and gravitational wave (GW) channel. The goal is to expand the CCSN search horizon with current and future detectors. In other words, we are finding a method to increase the significance of the astrophysical signals and to suppress as much as possible the noise. This can be seen as to improve the detection efficiency. Here, we are also involved in the supernova neutrino community, namely SuperNova Early Warning System (SNEWS2.0).
This effort is very delicate since CCSN rate is very low (~3 events per century in Milky Way), the detector search horizon only covers nearby galaxies (up to Small Magellanic Cloud, ~66 kpc, for LEN detectors and <10 kpc for GW detectors), as well as the real signals is difficult to distinguish from the noise. To get a higher CCSN rate, we should focus ourselves on expanding the search horizon to M31 and further (>1 Mpc). This is basically beyond the current detector capability for conservative CCSN models. Therefore, we are working on an analysis method to improve our capability to detect CCSNe for the current (and future) detectors.
We have summarised our methond to expand core-collapse search horizon that can be seen in Halim, et.al. 2020. Besides, a strategy to do the joint GW-LEN analysis can also be seen in a PhD thesis of our member (Halim, 2020), where the GW analysis uses coherentWave Burst (cWB) pipeline Necula, et.al. 2012 from LIGO-Virgo Collaboration.
Wiki Software
Consult the User's Guide for information on using the wiki software.
