Einstein Telescope

Last updated
Einstein Telescope
Named after Albert Einstein   OOjs UI icon edit-ltr-progressive.svg
Telescope style gravitational-wave observatory   OOjs UI icon edit-ltr-progressive.svg
Website www.et-gw.eu OOjs UI icon edit-ltr-progressive.svg

Einstein Telescope (ET) or Einstein Observatory, is a proposed third-generation ground-based gravitational wave detector, currently under study by some institutions in the European Union. It will be able to test Einstein's general theory of relativity in strong field conditions and realize precision gravitational wave astronomy.

Contents

The ET is a design study project supported by the European Commission under the Framework Programme 7 (FP7). It concerns the study and the conceptual design for a new research infrastructure in the emergent field of gravitational-wave astronomy.

Motivation

The evolution of the current gravitational wave detectors Advanced Virgo and Advanced LIGO, as second generation detectors, is well defined. Currently they have been upgraded to their so-called enhanced level and they are expected to reach their design sensitivity in the next few years. LIGO detected gravitational waves in 2015 and Virgo joined this experimental success with the first gravitational wave observed by three detectors GW170814 and shortly after with the first detection of a binary neutron star merger GW170817. Nevertheless, the sensitivity needed to test Einstein's theory of gravity in strong field conditions or to realize a precision gravitational wave astronomy, mainly of massive stellar bodies or of highly asymmetric (in mass) binary stellar systems, goes beyond the expected performances of the advanced detectors and of their subsequent upgrades. For example, the fundamental limitations at low frequency of the sensitivity of the second generation detectors are given by the seismic noise, the related gravitational gradient noise (so-called Newtonian noise) and the thermal noise of the suspension last stage and of the test masses.

To circumvent these limitations new infrastructures are necessary: an underground site for the detector, to limit the effect of the seismic noise, and cryogenic facilities to cool down the mirrors to directly reduce the thermal vibration of the test masses. [1]

Technical groups

Through its four technical working groups, the ET-FP7 project is addressing the basic questions in the realization of this proposed observatory: site location and characteristics (WP1), suspension design and technologies (WP2), detector topology and geometry (WP3), detection capabilities requirements and astrophysics potentialities (WP4).

Participants

ET is a design study project in the European Framework Programme (FP7). It has been proposed by 8 European leading gravitational wave experimental research institutes, coordinated by the European Gravitational Observatory: [2]

Current design

Although still in the early design study phase, the basic parameters are established. [3]

Like KAGRA, it will be located underground to reduce seismic noise and "gravity gradient noise" caused by nearby moving objects.

The arms will be 10 km long (compared to 4 km for LIGO, and 3 km for Virgo and KAGRA), and like LISA, there will be three arms in an equilateral triangle, with two detectors in each corner.

In order to measure the polarization of incoming gravitational waves and avoid having an orientation to which the telescope is insensitive, a minimum of two detectors are required. While this could be done with two 90° interferometers at 45° to each other, the triangular form allows the arms to be shared. The 60° arm angle reduces each interferometer's sensitivity, but that is made up for by the third detector, and the additional redundancy provides a useful cross-check.

Each of the three detectors would be composed of two interferometers, one optimized for operation below 30 Hz and one optimized for operation at higher frequencies.

The low-frequency interferometers (1 to 250 Hz) will use optics cooled to 10 K (−441.7 °F; −263.1 °C), with a beam power of about 18 kW in each arm cavity. [3] :15–16 The high-frequency ones (10 Hz to 10 kHz) will use room-temperature optics and a much higher recirculating beam power of 3 MW. [3] :15

ETpathfinder

A prototype, or testing facility, called the ETpathfinder was built at Maastricht University's Randwyck Campus in the Netherlands. [4] The facility was opened in November 2021 by Dutch Minister of Education, Culture and Science, Ingrid van Engelshoven. Project leader is Professor Stefan Hild. ETpathfinder will be a useful research centre in its own right after the ET has been built. The candidate sites for the ET are the Meuse–Rhine Euroregion, Sardinia, and Saxony. [5] [6] [7]

The Meuse-Rhine Euroregion proposal

In 2015, the Meuse-Rhine Euroregion, specifically the rural area between Maastricht, Liège and Aachen, was mentioned as one of the ET's possible sites. The Meuse-Rhine Euroregion has stable ground with little disturbance to the environment. But it also has a network of knowledge partners to cooperate with, companies that can supply the high-tech, and pleasant, accessible living and working environments.

The Einstein Telescope in the Meuse-Rhine Euroregion involves a triangular-shaped tunnel with arms of 10 kilometres long. The telescope will be located 250 to 300 metres underground. At the three vertices there will be large underground chambers. Laser beams run through the 10-kilometre arms, the tunnel tubes. A laser beam is split into two beams and these are reflected by mirrors at the ends of the arms in the underground chambers. From the three vertices, a lift will reach ground level. Maintenance will be carried out inside the tunnel via these shafts.

From 2021, Nikhef will carry out exploratory drilling in Terziet, Banholt, Cottessen and various locations in the German-Belgian border area. In April 2022, the Dutch gouvernment made €42 million available from the National Growth Fund for preparatory work of the ET and also reserved €870 million for construction. As the Einstein Telescope is an international project, the Netherlands, Belgium and Germany are cooperating in feasibility studies for the telescope in the Meuse-Rhine Euroregion. For example, studies are under way into the differences in planning laws and regulations and their significance for the project. Ultimately, these feasibility studies should lead to a bid book, which will be ready in 2025 at the earliest.

The Italian proposal

The Italian government is ready to support the candidacy of Sos Enattos (Sardinia) as a place for the construction of the telescope together with the Nobel prizewinner Giorgio Parisi. [8] [9] [10]

Sos Enattos was chosen for the functional characteristics of the project [11] of the site on the island:

In January 2021 seismological surveys were carried out to validate the site, installing 15 seismometric stations near the Sos Enattos mine. [16]

In September 2022, the Draghi government mandated the president of INFN Antonio Zoccoli to proceed with the creation of Italy's candidacy dossier, [17] [18] confirming the 350 million euro of economic commitment already allocated by the Sardinia Region. [19]

See also

Related Research Articles

<span class="mw-page-title-main">LIGO</span> Gravitational wave detector

The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory designed to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool. Two large observatories were built in the United States with the aim of detecting gravitational waves by laser interferometry. These observatories use mirrors spaced four kilometers apart which are capable of detecting a change of less than one ten-thousandth the charge diameter of a proton.

<span class="mw-page-title-main">Laser Interferometer Space Antenna</span> European space mission to measure gravitational waves

The Laser Interferometer Space Antenna (LISA) is a planned space probe to detect and accurately measure gravitational waves—tiny ripples in the fabric of spacetime—from astronomical sources. LISA will be the first dedicated space-based gravitational-wave observatory. It aims to measure gravitational waves directly by using laser interferometry. The LISA concept features three spacecraft arranged in an equilateral triangle with each side 2.5 million kilometers long, flying in an Earth-like orbit heliocentric orbit. The distance between the satellites is precisely monitored to detect a passing gravitational wave.

<span class="mw-page-title-main">Einstein@Home</span> BOINC volunteer computing project that analyzes data from LIGO to detect gravitational waves

Einstein@Home is a volunteer computing project that searches for signals from spinning neutron stars in data from gravitational-wave detectors, from large radio telescopes, and from a gamma-ray telescope. Neutron stars are detected by their pulsed radio and gamma-ray emission as radio and/or gamma-ray pulsars. They also might be observable as continuous gravitational wave sources if they are rapidly spinning and non-axisymmetrically deformed. The project was officially launched on 19 February 2005 as part of the American Physical Society's contribution to the World Year of Physics 2005 event.

<span class="mw-page-title-main">Max Planck Institute for Gravitational Physics</span>

The Max Planck Institute for Gravitational Physics is a Max Planck Institute whose research is aimed at investigating Einstein's theory of relativity and beyond: Mathematics, quantum gravity, astrophysical relativity, and gravitational-wave astronomy. The institute was founded in 1995 and is located in the Potsdam Science Park in Golm, Potsdam and in Hannover where it closely collaborates with the Leibniz University Hannover. Both the Potsdam and the Hannover parts of the institute are organized in three research departments and host a number of independent research groups.

<span class="mw-page-title-main">GEO600</span> Gravitational wave detector in Germany

GEO600 is a gravitational wave detector located near Sarstedt, a town 20 km to the south of Hanover, Germany. It is designed and operated by scientists from the Max Planck Institute for Gravitational Physics, Max Planck Institute of Quantum Optics and the Leibniz Universität Hannover, along with University of Glasgow, University of Birmingham and Cardiff University in the United Kingdom, and is funded by the Max Planck Society and the Science and Technology Facilities Council (STFC). GEO600 is capable of detecting gravitational waves in the frequency range 50 Hz to 1.5 kHz, and is part of a worldwide network of gravitational wave detectors. This instrument, and its sister interferometric detectors, when operational, are some of the most sensitive gravitational wave detectors ever designed. They are designed to detect relative changes in distance of the order of 10−21, about the size of a single atom compared to the distance from the Sun to the Earth. Construction on the project began in 1995.

<span class="mw-page-title-main">KAGRA</span> Japanese underground gravitational wave detector

The Kamioka Gravitational Wave Detector (KAGRA) is a large interferometer designed to detect gravitational waves predicted by the general theory of relativity. KAGRA is a Michelson interferometer that is isolated from external disturbances: its mirrors and instrumentation are suspended and its laser beam operates in a vacuum. The instrument's two arms are three kilometres long and located underground at the Kamioka Observatory which is near the Kamioka section of the city of Hida in Gifu Prefecture, Japan.

<span class="mw-page-title-main">Virgo interferometer</span> Gravitational wave detector in Santo Stefano a Macerata, Tuscany, Italy

The Virgo interferometer is a large Michelson interferometer designed to detect the gravitational waves predicted by general relativity. It is in Santo Stefano a Macerata, near the city of Pisa, Italy. The instrument's two arms are three kilometres long and contain its mirrors and instrumentation inside an ultra-high vacuum.

<span class="mw-page-title-main">Gravitational wave</span> Propagating spacetime ripple

Gravitational waves are waves of the intensity of gravity that are generated by the accelerated masses of binary stars and other motions of gravitating masses, and propagate as waves outward from their source at the speed of light. They were first proposed by Oliver Heaviside in 1893 and then later by Henri Poincaré in 1905 as the gravitational equivalent of electromagnetic waves. Gravitational waves are sometimes called gravity waves, but gravity waves typically refer to displacement waves in fluids. In 1916 Albert Einstein demonstrated that gravitational waves result from his general theory of relativity as ripples in spacetime.

<span class="mw-page-title-main">Gravitational-wave observatory</span> Device used to measure gravitational waves

A gravitational-wave detector is any device designed to measure tiny distortions of spacetime called gravitational waves. Since the 1960s, various kinds of gravitational-wave detectors have been built and constantly improved. The present-day generation of laser interferometers has reached the necessary sensitivity to detect gravitational waves from astronomical sources, thus forming the primary tool of gravitational-wave astronomy.

<span class="mw-page-title-main">Gravitational-wave astronomy</span> Branch of astronomy using gravitational waves

Gravitational-wave astronomy is a subfield of astronomy concerned with the detection and study of gravitational waves emitted by astrophysical sources.

The LIGO Scientific Collaboration (LSC) is a scientific collaboration of international physics institutes and research groups dedicated to the search for gravitational waves.

The Australian International Gravitational Observatory (AIGO) is a research facility located near Gingin, north of Perth in Western Australia. It is part of a worldwide effort to directly detect gravitational waves. Note that these are a major prediction of the general theory of relativity and are not to be confused with gravity waves, a phenomenon studied in fluid mechanics.

David Howard Reitze is an American laser physicist who is professor of physics at the University of Florida and served as the scientific spokesman of the Laser Interferometer Gravitational-Wave Observatory (LIGO) experiment in 2007-2011. In August 2011, he took a leave of absence from the University of Florida to be the Executive Director of LIGO, stationed at the California Institute of Technology, Pasadena, California. He obtained his BA in 1983 from Northwestern University, his PhD in physics from the University of Texas at Austin in 1990, and had positions at Bell Communications Research and Lawrence Livermore National Laboratory, before taking his faculty position at the University of Florida. He is a Fellow of the American Physical Society, the Optical Society, and the American Association for the Advancement of Science.

<span class="mw-page-title-main">Barry Barish</span> American physicist

Barry Clark Barish is an American experimental physicist and Nobel Laureate. He is a Linde Professor of Physics, emeritus at California Institute of Technology and a leading expert on gravitational waves.

<span class="mw-page-title-main">LISA Pathfinder</span> 2015 European Space Agency spacecraft

LISA Pathfinder, formerly Small Missions for Advanced Research in Technology-2 (SMART-2), was an ESA spacecraft that was launched on 3 December 2015 on board Vega flight VV06. The mission tested technologies needed for the Laser Interferometer Space Antenna (LISA), an ESA gravitational wave observatory planned to be launched in 2035. The scientific phase started on 8 March 2016 and lasted almost sixteen months. In April 2016 ESA announced that LISA Pathfinder demonstrated that the LISA mission is feasible.

<span class="mw-page-title-main">First observation of gravitational waves</span> 2015 direct detection of gravitational waves by the LIGO and VIRGO interferometers

The first direct observation of gravitational waves was made on 14 September 2015 and was announced by the LIGO and Virgo collaborations on 11 February 2016. Previously, gravitational waves had been inferred only indirectly, via their effect on the timing of pulsars in binary star systems. The waveform, detected by both LIGO observatories, matched the predictions of general relativity for a gravitational wave emanating from the inward spiral and merger of a pair of black holes of around 36 and 29 solar masses and the subsequent "ringdown" of the single resulting black hole. The signal was named GW150914. It was also the first observation of a binary black hole merger, demonstrating both the existence of binary stellar-mass black hole systems and the fact that such mergers could occur within the current age of the universe.

<span class="mw-page-title-main">GW170817</span> Gravitational-wave signal detected in 2017

GW 170817 was a gravitational wave (GW) signal observed by the LIGO and Virgo detectors on 17 August 2017, originating from the shell elliptical galaxy NGC 4993. The signal was produced by the last moments of the inspiral process of a binary pair of neutron stars, ending with their merger. It was the first GW observation to be confirmed by non-gravitational means. Unlike the five previous GW detections—which were of merging black holes and thus not expected to produce a detectable electromagnetic signal—the aftermath of this merger was seen across the electromagnetic spectrum by 70 observatories on 7 continents and in space, marking a significant breakthrough for multi-messenger astronomy. The discovery and subsequent observations of GW 170817 were given the Breakthrough of the Year award for 2017 by the journal Science.

<span class="mw-page-title-main">Rana X. Adhikari</span> American experimental physicist (born 1974)

Rana X. Adhikari is an American experimental physicist. He is a professor of physics at the California Institute of Technology (Caltech) and an associate faculty member of the International Centre for Theoretical Sciences of Tata Institute of Fundamental Research (ICTS-TIFR).

Lisa Barsotti is a research scientist at the Massachusetts Institute of Technology Kavli Institute.

Ground-based interferometric gravitational-wave search refers to methods and devices used to search and detect gravitational waves based on interferometers built on the ground. Most of current gravitational wave observations have been made using these techniques; the first one was made in 2015 by the two LIGO detectors. The current major detectors are the two LIGO in the United States, Virgo in Italy and KAGRA in Japan, which are all part of the second generation of detectors; future projects include LIGO-India as part of the second generation, and the Einstein Telescope and Cosmic Explorer forming a third generation.

References

  1. Stefan Hild; Simon Chelkowski; Andreas Freise (2008-11-24), Pushing towards the ET sensitivity using 'conventional' technology, arXiv: 0810.0604 , Bibcode:2008arXiv0810.0604H
  2. ET Design Study Participants Archived 2016-08-15 at the Wayback Machine 10 October 2008.
  3. 1 2 3 ET Science Team (June 28, 2011). Einstein gravitational wave telescope conceptual design study (Report). ET-0106C-10. Archived from the original on October 4, 2017. Retrieved October 4, 2017.
  4. Prototype Einstein Telescope komt in pand 'zwarte doos' in Maastricht, 6 August 2019
  5. 'Looking back on ETpathfinder's opening', maastrichtuniversity.nl, 9 November 2021.
  6. 'ET - Site Studies and Characterization', agenda.infn.it, 20 August 2022.
  7. 'ET SPB and WP4 of ET-PP', 'indico.ego-gw.it', 20 August 2022.
  8. "Einstein Telescope, presto l'annuncio della candidatura italiana - Scienza & Tecnica". ANSA.it (in Italian). 2023-03-07. Retrieved 2023-03-18.
  9. "It's official! Italy on the race for the Einstein Telescope | GARR". www.garr.it. Retrieved 2023-03-18.
  10. "Home". ET (in Italian). Retrieved 2023-05-12.
  11. 1 2 "Einstein Telescope, la sfida sarda per il futuro". L'Unione Sarda.it (in Italian). 2020-11-25. Retrieved 2023-03-18.
  12. Di Giovanni, Matteo; Giunchi, Carlo; Saccorotti, Gilberto; Berbellini, Andrea; Boschi, Lapo; Olivieri, Marco; De Rosa, Rosario; Naticchioni, Luca; Oggiano, Giacomo; Carpinelli, Massimo; d'Urso, Domenico; Cuccuru, Stefano; Sipala, Valeria; Calloni, Enrico; Di Fiore, Luciano; Grado, Aniello; Migoni, Carlo; Cardini, Alessandro; Paoletti, Federico; Fiori, Irene; Harms, Jan; Majorana, Ettore; Rapagnani, Piero; Ricci, Fulvio; Punturo, Michele; et al. (Matteo Di Giovanni, Carlo Giunchi, Gilberto Saccorotti, Andrea Berbellini, Lapo Boschi, Marco Olivieri, Rosario De Rosa, Luca Naticchioni, Giacomo Oggiano, Massimo Carpinelli, Domenico D’Urso, Stefano Cuccuru, Valeria Sipala, Enrico Calloni, Luciano Di Fiore, Aniello Grado, Carlo Migoni, Alessandro Cardini, Federico Paoletti, Irene Fiori, Jan Harms, Ettore Majorana, Piero Rapagnani, Fulvio Ricci, Michele Punturo) (2020). "A Seismological Study of the Sos Enattos Area—the Sardinia Candidate Site for the Einstein Telescope". Seismological Research Letters. 92: 352–364. doi:10.1785/0220200186. S2CID   228918534.
  13. "Un'ex miniera in Sardegna è fra i siti più 'silenziosi' del mondo". Agi (in Italian). Retrieved 2023-03-18.
  14. 1 2 "Einstein Telescope – INFN – Sezione di Cagliari" (in Italian). Retrieved 2023-03-18.
  15. "Einstein Telescope, progetto da 4,5 mld e 36 mila occupati - Sardegna". Agenzia ANSA (in Italian). 2022-03-16. Retrieved 2023-03-18.
  16. Inaf, Redazione Media (2021-01-20). "Einstein Telescope, iniziano le misure geofisiche". MEDIA INAF (in Italian). Retrieved 2023-03-18.
  17. "Dal Governo sostegno alla proposta di ospitare l'Einstein Telescope in Italia | www.governo.it". 2022-09-27. Archived from the original on 2022-09-27. Retrieved 2023-03-18.
  18. "Draghi backs hosting Einstein Telescope in Sardinia - English". ANSA.it. 2022-09-27. Retrieved 2023-03-18.
  19. Stampa, Ufficio (2022-03-16). "Progetto Einstein Telescope in IV Commissione. "Occasione unica per la Sardegna". La Regione pronta a investire 350 milioni di euro". Consiglio regionale della Sardegna (in Italian). Retrieved 2023-03-18.

Further reading