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= Einstein Telescope =
 
= Einstein Telescope =
 
[[File:ETArtist.jpg|Einstein Telescope (artistic conception)|thumb]]
 
[[File:ETArtist.jpg|Einstein Telescope (artistic conception)|thumb]]
The Einstein Telescope (ET) is a proposed next-generation, gravitational-wave (GW) detector in a new underground facility [http://www.et-gw.eu/ [ET home page<nowiki>]</nowiki>]. 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 [https://arxiv.org/abs/1012.0908 [ET detector configuration<nowiki>]</nowiki>].
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The Einstein Telescope (ET) is a proposed underground infrastructure to host a third-generation, gravitational-wave observatory [http://www.et-gw.eu/ [ET home page<nowiki>]</nowiki>]. It builds on the success of current, second-generation laser-interferometric detectors Advanced Virgo and Advanced LIGO, whose breakthrough discoveries of merging black holes (BHs) and neutron stars over the past 5 years have ushered scientists into the new era of gravitational-wave astronomy. The Einstein Telescope will achieve a greatly improved sensitivity by increasing the size of the interferometer from the 3km arm length of the Virgo detector to 10km, and by implementing a series of new technologies. These include a cryogenic system to cool some of the main optics to 10 – 20K, new quantum technologies to reduce the fluctuations of the light, and a set of infrastructural and active noise-mitigation measures to reduce environmental perturbations.  
  
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 [https://arxiv.org/abs/1912.02622 [ET science case<nowiki>]</nowiki>]. 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 [https://arxiv.org/abs/2001.11173 [Voyager<nowiki>]</nowiki>]and Cosmic Explorer [https://cosmicexplorer.org/ [Cosmic Explorer<nowiki>]</nowiki>], which will further increase the science that can be done through GW observations [https://gwic.ligo.org/3Gsubcomm/documents/3G-observatory-science-case.pdf [3G science case<nowiki>]</nowiki>].
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The Einstein Telescope will make it possible, for the first time, to explore the Universe through gravitational waves along its cosmic history up to the cosmological dark ages, shedding light on open questions of fundamental physics and cosmology [https://arxiv.org/abs/1912.02622 [ET science case<nowiki>]</nowiki>]. It will probe the physics near black-hole horizons (from tests of general relativity to quantum gravity), help understanding the nature of dark matter (such as primordial BHs, axion clouds, dark matter accreting on compact objects), and the nature of dark energy and possible modifications of general relativity at cosmological scales. Exploiting the ET sensitivity and frequency band, the entire population of stellar and intermediate mass black holes will be accessible over the entire history of the Universe, enabling to understand their origin (stellar versus primordial), evolution, and demography. ET will observe the neutron-star inspiral phase and the onset of tidal effects with high signal-to-noise ratio providing an unprecedented insight into the interior structure of neutron stars and probing fundamental properties of matter in a completely unexplored regime (QCD at ultra-high densities and possible exotic states of matter). The excellent sensitivity extending to kilohertz frequencies will also allow us to probe details of the merger and post-merger phase. ET will operate together with a new innovative generation of electromagnetic observatories covering the band from radio to gamma rays (such as the Square Kilometer Array, the Vera Rubin Observatory, E-ELT, Athena, CTA).
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The beginning of construction is foreseen in 2026 with the goal to start observations in 2035. Two candidate sites are under investigation: one in Sardinia and one in the Euregio Meuse-Rhine. Site-characterization studies are under way towards a site selection, which is expected for 2024. The evaluation of the sites must consider the feasibility of the construction and predict the impact of the local environment on the detector sensitivity and operation. The gravitational-wave community in the US is currently working on its own third-generation detector concepts Voyager [https://arxiv.org/abs/2001.11173 [Voyager<nowiki>]</nowiki>]and Cosmic Explorer [https://cosmicexplorer.org/ [Cosmic Explorer<nowiki>]</nowiki>] towards a future global detector network with the Einstein Telescope [https://gwic.ligo.org/3Gsubcomm/documents/3G-observatory-science-case.pdf [3G science case<nowiki>]</nowiki>].
  
 
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 [https://arxiv.org/abs/1710.04638 [THESEUS<nowiki>]</nowiki>], E-ELT [https://www.eso.org/sci/facilities/eelt/docs/e-elt_executivesummary.pdf [E-ELT<nowiki>]</nowiki>], or VRO (formerly LSST) [https://en.wikipedia.org/wiki/Vera_C._Rubin_Observatory [VRO<nowiki>]</nowiki>].
 
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 [https://arxiv.org/abs/1710.04638 [THESEUS<nowiki>]</nowiki>], E-ELT [https://www.eso.org/sci/facilities/eelt/docs/e-elt_executivesummary.pdf [E-ELT<nowiki>]</nowiki>], or VRO (formerly LSST) [https://en.wikipedia.org/wiki/Vera_C._Rubin_Observatory [VRO<nowiki>]</nowiki>].

Revision as of 20:15, 11 September 2020

GSSI Gravity Group

This page serves 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.

Members

Einstein Telescope

File:ETArtist.jpg
Einstein Telescope (artistic conception)

The Einstein Telescope (ET) is a proposed underground infrastructure to host a third-generation, gravitational-wave observatory [ET home page]. It builds on the success of current, second-generation laser-interferometric detectors Advanced Virgo and Advanced LIGO, whose breakthrough discoveries of merging black holes (BHs) and neutron stars over the past 5 years have ushered scientists into the new era of gravitational-wave astronomy. The Einstein Telescope will achieve a greatly improved sensitivity by increasing the size of the interferometer from the 3km arm length of the Virgo detector to 10km, and by implementing a series of new technologies. These include a cryogenic system to cool some of the main optics to 10 – 20K, new quantum technologies to reduce the fluctuations of the light, and a set of infrastructural and active noise-mitigation measures to reduce environmental perturbations.

The Einstein Telescope will make it possible, for the first time, to explore the Universe through gravitational waves along its cosmic history up to the cosmological dark ages, shedding light on open questions of fundamental physics and cosmology [ET science case]. It will probe the physics near black-hole horizons (from tests of general relativity to quantum gravity), help understanding the nature of dark matter (such as primordial BHs, axion clouds, dark matter accreting on compact objects), and the nature of dark energy and possible modifications of general relativity at cosmological scales. Exploiting the ET sensitivity and frequency band, the entire population of stellar and intermediate mass black holes will be accessible over the entire history of the Universe, enabling to understand their origin (stellar versus primordial), evolution, and demography. ET will observe the neutron-star inspiral phase and the onset of tidal effects with high signal-to-noise ratio providing an unprecedented insight into the interior structure of neutron stars and probing fundamental properties of matter in a completely unexplored regime (QCD at ultra-high densities and possible exotic states of matter). The excellent sensitivity extending to kilohertz frequencies will also allow us to probe details of the merger and post-merger phase. ET will operate together with a new innovative generation of electromagnetic observatories covering the band from radio to gamma rays (such as the Square Kilometer Array, the Vera Rubin Observatory, E-ELT, Athena, CTA).

The beginning of construction is foreseen in 2026 with the goal to start observations in 2035. Two candidate sites are under investigation: one in Sardinia and one in the Euregio Meuse-Rhine. Site-characterization studies are under way towards a site selection, which is expected for 2024. The evaluation of the sites must consider the feasibility of the construction and predict the impact of the local environment on the detector sensitivity and operation. The gravitational-wave community in the US is currently working on its own third-generation detector concepts Voyager [Voyager]and Cosmic Explorer [Cosmic Explorer] towards a future global detector network with the Einstein Telescope [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

Sardinia candidate site

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

Cryogenics

Environmental Noise

Detector Control

Earthquake early warning with gravitational sensors

Quantum noise modeling and detector configurations

Thermal noise in GW detectors

Multi-messenger astronomy

Cosmology with multi-messenger transients

Multimessenger Search of Core-Collapse Supernovae

Wiki Software

Consult the User's Guide for information on using the wiki software.

Getting started