LIGO
Alternative names | LIGO |
---|---|
Location(s) | Hanford Site, Washington and Livingston, Louisiana, US |
Coordinates | LIGO Hanford Observatory: 46°27′18.52″N 119°24′27.56″W / 46.4551444°N 119.4076556°W LIGO Livingston Observatory: 30°33′46.42″N 90°46′27.27″W / 30.5628944°N 90.7742417°W |
Organization | LIGO Scientific Collaboration |
Wavelength | 43 km (7.0 kHz)–10,000 km (30 Hz) |
Built | 1994–2002 |
First light | 23 August 2002 |
Telescope style | gravitational-wave observatory |
Length | 4,000 m (13,123 ft 4 in) |
Website | www |
LIGO observatories in the Contiguous United States | |
Related media on Commons | |
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.[1] 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[clarification needed] of less than one ten-thousandth the charge diameter of a proton.[2]
The initial LIGO observatories were funded by the United States
They collected data from 2002 to 2010 but no gravitational waves were detected.The Advanced LIGO Project to enhance the original LIGO detectors began in 2008 and continues to be supported by the NSF, with important contributions from the United Kingdom's Science and Technology Facilities Council, the Max Planck Society of Germany, and the Australian Research Council.[5][6] The improved detectors began operation in 2015. The detection of gravitational waves was reported in 2016 by the LIGO Scientific Collaboration (LSC) and the Virgo Collaboration with the international participation of scientists from several universities and research institutions. Scientists involved in the project and the analysis of the data for gravitational-wave astronomy are organized by the LSC, which includes more than 1000 scientists worldwide,[7][8][9] as well as 440,000 active Einstein@Home users as of December 2016[update].[10]
LIGO is the largest and most ambitious project ever funded by the NSF.
Observations are made in "runs". As of January 2022[update], LIGO has made three runs (with one of the runs divided into two "subruns"), and made 90
The gravitational wave observatories LIGO, Virgo in Italy, and KAGRA in Japan are coordinating to continue observations after the COVID-caused stop, and LIGO's O4 observing run started on 24 May 2023.[19][20] LIGO projects a sensitivity goal of 160–190 Mpc for binary neutron star mergers (sensitivities: Virgo 80–115 Mpc, KAGRA greater than 1 Mpc).[21]
History
Background
The LIGO concept built upon early work by many scientists to test a component of
Prototype interferometric gravitational wave detectors (interferometers) were built in the late 1960s by
In 1980, the NSF funded the study of a large interferometer led by MIT (Paul Linsay, Peter Saulson, Rainer Weiss), and the following year, Caltech constructed a 40-meter prototype (Ronald Drever and Stan Whitcomb). The MIT study established the feasibility of interferometers at a 1-kilometer scale with adequate sensitivity.[22][26]
Under pressure from the NSF, MIT and Caltech were asked to join forces to lead a LIGO project based on the MIT study and on experimental work at Caltech, MIT, Glasgow, and
From 1989 through 1994, LIGO failed to progress technically and organizationally. Only political efforts continued to acquire funding.[22][31] Ongoing funding was routinely rejected until 1991, when the U.S. Congress agreed to fund LIGO for the first year for $23 million. However, requirements for receiving the funding were not met or approved, and the NSF questioned the technological and organizational basis of the project.[27][28] By 1992, LIGO was restructured with Drever no longer a direct participant.[22][31][32][33] Ongoing project management issues and technical concerns were revealed in NSF reviews of the project, resulting in the withholding of funds until they formally froze spending in 1993.[22][31][34][35]
In 1994, after consultation between relevant NSF personnel, LIGO's scientific leaders, and the presidents of MIT and Caltech, Vogt stepped down and
Observations begin
Initial LIGO operations between 2002 and 2010 did not detect any gravitational waves. In 2004, under Barish, the funding and groundwork were laid for the next phase of LIGO development (called "Enhanced LIGO"). This was followed by a multi-year shut-down while the detectors were replaced by much improved "Advanced LIGO" versions.[38][39] Much of the research and development work for the LIGO/aLIGO machines was based on pioneering work for the GEO600 detector at Hannover, Germany.[40][41] By February 2015, the detectors were brought into engineering mode in both locations.[42]
By mid-September 2015, "the world's largest gravitational-wave facility" completed a five-year US$200-million overhaul at a total cost of $620 million.[9][43] On 18 September 2015, Advanced LIGO began its first formal science observations at about four times the sensitivity of the initial LIGO interferometers.[44] Its sensitivity was to be further enhanced until it was planned to reach design sensitivity around 2021.[update][45]
Detections
On 11 February 2016, the LIGO Scientific Collaboration and
Current executive director David Reitze announced the findings at a media event in Washington D.C., while executive director emeritus Barry Barish presented the first scientific paper of the findings at CERN to the physics community.[48]
On 2 May 2016, members of the
On 16 June 2016 LIGO announced a second signal was detected from the merging of two black holes with 14.2 and 7.5 times the mass of the Sun. The signal was picked up on 26 December 2015, at 3:38 UTC.[50]
The detection of a third black hole merger, between objects of 31.2 and 19.4 solar masses, occurred on 4 January 2017 and was announced on 1 June 2017.[51][52] Laura Cadonati was appointed the first deputy spokesperson.[53]
A fourth detection of a black hole merger, between objects of 30.5 and 25.3 solar masses, was observed on 14 August 2017 and was announced on 27 September 2017.[54]
In 2017, Weiss, Barish, and Thorne received the Nobel Prize in Physics "for decisive contributions to the LIGO detector and the observation of gravitational waves." Weiss was awarded one-half of the total prize money, and Barish and Thorne each received a one-quarter prize.[55][56][57]
After shutting down for improvements, LIGO resumed operation on 26 March 2019, with Virgo joining the network of gravitational-wave detectors on 1 April 2019.[58] Both ran until 27 March 2020, when the COVID-19 pandemic halted operations.[18] During the COVID shutdown, LIGO underwent a further upgrade in sensitivity, and observing run O4 with the new sensitivity began on 24 May 2023.[19]
Mission
LIGO's mission is to directly observe gravitational waves of cosmic origin. These waves were first predicted by Einstein's
Direct detection of gravitational waves had long been sought. Their discovery has launched a new branch of astronomy to complement
In fact as early as the 1960s, and perhaps before that, there were papers published on wave resonance of light and gravitational waves.
Since the early 1990s, physicists have thought that technology has evolved to the point where detection of gravitational waves—of significant astrophysical interest—is now possible.[64]
In August 2002, LIGO began its search for cosmic gravitational waves. Measurable emissions of gravitational waves are expected from binary systems (collisions and coalescences of
Observatories
LIGO operates two gravitational wave observatories in unison: the LIGO Livingston Observatory (30°33′46.42″N 90°46′27.27″W / 30.5628944°N 90.7742417°W) in Livingston, Louisiana, and the LIGO Hanford Observatory, on the DOE Hanford Site (46°27′18.52″N 119°24′27.56″W / 46.4551444°N 119.4076556°W), located near Richland, Washington. These sites are separated by 3,002 kilometers (1,865 miles) straight line distance through the earth, but 3,030 kilometers (1,883 miles) over the surface. Since gravitational waves are expected to travel at the speed of light, this distance corresponds to a difference in gravitational wave arrival times of up to ten milliseconds. Through the use of trilateration, the difference in arrival times helps to determine the source of the wave, especially when a third similar instrument like Virgo, located at an even greater distance in Europe, is added.[65]
Each observatory supports an L-shaped
The LIGO Livingston Observatory houses one laser
The LIGO Hanford Observatory houses one interferometer, almost identical to the one at the Livingston Observatory. During the Initial and Enhanced LIGO phases, a half-length interferometer operated in parallel with the main interferometer. For this 2 km interferometer, the
Operation
The parameters in this section refer to the Advanced LIGO experiment. The primary interferometer consists of two beam lines of 4 km length which form a power-recycled Michelson interferometer with Gires–Tournois etalon arms. A pre-stabilized 1064 nm Nd:YAG laser emits a beam with a power of 20 W that passes through a power recycling mirror. The mirror fully transmits light incident from the laser and reflects light from the other side increasing the power of the light field between the mirror and the subsequent beam splitter to 700 W. From the beam splitter the light travels along two orthogonal arms. By the use of partially reflecting mirrors, Fabry–Pérot cavities are created in both arms that increase the effective path length of laser light in the arm from 4 km to approximately 1,200 km.[66] The power of the light field in the cavity is 100 kW.[67]
When a gravitational wave passes through the interferometer, the spacetime in the local area is altered. Depending on the source of the wave and its polarization, this results in an effective change in length of one or both of the cavities. The effective length change between the beams will cause the light currently in the cavity to become very slightly out of
After an equivalent of approximately 280 trips down the 4 km length to the far mirrors and back again,[69] the two separate beams leave the arms and recombine at the beam splitter. The beams returning from two arms are kept out of phase so that when the arms are both in coherence and interference (as when there is no gravitational wave passing through), their light waves subtract, and no light should arrive at the photodiode. When a gravitational wave passes through the interferometer, the distances along the arms of the interferometer are shortened and lengthened, causing the beams to become slightly less out of phase. This results in the beams coming in phase, creating a resonance, hence some light arrives at the photodiode and indicates a signal. Light that does not contain a signal is returned to the interferometer using a power recycling mirror, thus increasing the power of the light in the arms.
In actual operation, noise sources can cause movement in the optics, producing similar effects to real gravitational wave signals; a great deal of the art and complexity in the instrument is in finding ways to reduce these spurious motions of the mirrors.[70] Background noise and unknown errors (which happen daily) are in the order of 10−20, while gravitational wave signals are around 10−22. After noise reduction, a signal-to-noise ratio around 20 can be achieved, or higher when combined with other gravitational wave detectors around the world.[71]
Observations
Based on current models of astronomical events, and the predictions of the
In their fourth Science Run at the end of 2004, the LIGO detectors demonstrated sensitivities in measuring these displacements to within a factor of two of their design.
During LIGO's fifth Science Run in November 2005, sensitivity reached the primary design specification of a detectable strain of one part in 1021 over a 100 Hz bandwidth. The baseline inspiral of two roughly solar-mass neutron stars is typically expected to be observable if it occurs within about 8 million
In February 2007, GRB 070201, a short gamma-ray burst arrived at Earth from the direction of the Andromeda Galaxy. The prevailing explanation of most short gamma-ray bursts is the merger of a neutron star with either a neutron star or a black hole. LIGO reported a non-detection for GRB 070201, ruling out a merger at the distance of Andromeda with high confidence. Such a constraint was predicated on LIGO eventually demonstrating a direct detection of gravitational waves.[75]
Enhanced LIGO
After the completion of Science Run 5, initial LIGO was upgraded with certain technologies, planned for Advanced LIGO but available and able to be retrofitted to initial LIGO, which resulted in an improved-performance configuration dubbed Enhanced LIGO.[76] Some of the improvements in Enhanced LIGO included:
- Increased laser power
- Homodyne detection
- Output mode cleaner
- In-vacuum readout hardware
Science Run 6 (S6) began in July 2009 with the enhanced configurations on the 4 km detectors.[77] It concluded in October 2010, and the disassembly of the original detectors began.
Advanced LIGO
After 2010, LIGO went offline for several years for a major upgrade, installing the new Advanced LIGO detectors in the LIGO Observatory infrastructures.
The project continued to attract new members, with the Australian National University and University of Adelaide contributing to Advanced LIGO, and by the time the LIGO Laboratory started the first observing run 'O1' with the Advanced LIGO detectors in September 2015, the LIGO Scientific Collaboration included more than 900 scientists worldwide.[9]
The first observing run operated at a sensitivity roughly three times greater than Initial LIGO,[79] and a much greater sensitivity for larger systems with their peak radiation at lower audio frequencies.[80]
On 11 February 2016, the LIGO and
On 15 June 2016, LIGO announced the detection of a second gravitational wave event, recorded on 26 December 2015, at 3:38 UTC. Analysis of the observed signal indicated that the event was caused by the merger of two black holes with masses of 14.2 and 7.5 solar masses, at a distance of 1.4 billion light years.[50] The signal was named GW151226.[84]
The second observing run (O2) ran from 30 November 2016
The third run (O3) began on 1 April 2019
Future observing runs will be interleaved with commissioning efforts to further improve the sensitivity. It was aimed to achieve design sensitivity in 2021;[45] the next observing run (O4) was planned to start in December 2022,[95] but the date was pushed back to 24 May 2023.[19][96]
Future
LIGO-India
The LIGO-India project is a collaboration between LIGO Laboratory and the LIGO-India consortium: Institute of Plasma Research, Gandhinagar; IUCAA (Inter-University Centre for Astronomy and Astrophysics), Pune and Raja Ramanna Centre for Advanced Technology, Indore.
The expansion of worldwide activities in gravitational-wave detection to produce an effective global network has been a goal of LIGO for many years. In 2010, a developmental roadmap[97] issued by the Gravitational Wave International Committee (GWIC) recommended that an expansion of the global array of interferometric detectors be pursued as a highest priority. Such a network would afford astrophysicists with more robust search capabilities and higher scientific yields. The current agreement between the LIGO Scientific Collaboration and the Virgo collaboration links three detectors of comparable sensitivity and forms the core of this international network. Studies indicate that the localization of sources by a network that includes a detector in India would provide significant improvements.[98][99] Improvements in localization averages are predicted to be approximately an order of magnitude, with substantially larger improvements in certain regions of the sky.
The NSF was willing to permit this relocation, and its consequent schedule delays, as long as it did not increase the LIGO budget. Thus, all costs required to build a laboratory equivalent to the LIGO sites to house the detector would have to be borne by the host country.[100] The first potential distant location was at AIGO in Western Australia,[101] however the Australian government was unwilling to commit funding by 1 October 2011 deadline.
A location in India was discussed at a Joint Commission meeting between India and the US in June 2012.[102] In parallel, the proposal was evaluated by LIGO's funding agency, the NSF. As the basis of the LIGO-India project entails the transfer of one of LIGO's detectors to India, the plan would affect work and scheduling on the Advanced LIGO upgrades already underway. In August 2012, the U.S. National Science Board approved the LIGO Laboratory's request to modify the scope of Advanced LIGO by not installing the Hanford "H2" interferometer, and to prepare it instead for storage in anticipation of sending it to LIGO-India.[103] In India, the project was presented to the Department of Atomic Energy and the Department of Science and Technology for approval and funding. On 17 February 2016, less than a week after LIGO's landmark announcement about the detection of gravitational waves, Indian Prime Minister Narendra Modi announced that the Cabinet has granted 'in-principle' approval to the LIGO-India mega science proposal.[104]
A site near pilgrimage site of Aundha Nagnath in the Hingoli district of state Maharashtra in western India has been selected.[105][106]
On 7 April 2023, the LIGO-India project was approved by the Cabinet of Government of India. Construction is to begin in Maharashtra's Hingoli district at a cost of INR 2600 crores.[107]
A+
Like Enhanced LIGO, certain improvements will be retrofitted to the existing Advanced LIGO instrument. These are referred to as A+ proposals, and are planned for installation starting from 2019 until the upgraded detector is operational in 2024.[108] The changes would almost double Advanced LIGO's sensitivity,[109][110] and increase the volume of space searched by a factor of seven.[111] The upgrades include:
- Improvements to the mirror suspension system.[112]
- Increased reflectivity of the mirrors.
- Using frequency-dependent squeezed light, which would simultaneously decrease radiation pressure at low frequencies and shot noiseat high frequencies, and
- Improved mirror coatings with lower mechanical loss.[113]
Because the final LIGO output photodetector is sensitive to phase, and not amplitude, it is possible to squeeze the signal so there is less phase noise and more amplitude noise, without violating the quantum mechanical limit on their product.[114] This is done by injecting a "squeezed vacuum state" into the dark port (interferometer output) which is quieter, in the relevant parameter, than simple darkness. Such a squeezing upgrade was installed at both LIGO sites prior to the third observing run.[115] The A+ improvement will see the installation of an additional optical cavity that acts to rotate the squeezing quadrature from phase-squeezed at high frequencies (above 50 Hz) to amplitude-squeezed at low frequencies, thereby also mitigating low-frequency radiation pressure noise.
LIGO Voyager
A third-generation detector at the existing LIGO sites is being planned under the name "LIGO Voyager" to improve the sensitivity by an additional factor of two, and halve the low-frequency cutoff to 10 Hz.[116] Plans call for the glass mirrors and 1064 nm lasers to be replaced by even larger 160 kg silicon test masses, cooled to 123 K (a temperature achievable with liquid nitrogen), and a change to a longer laser wavelength in the 1500–2200 nm range at which silicon is transparent. (Many documents assume a wavelength of 1550 nm, but this is not final.)
Voyager would be an upgrade to A+, to be operational around 2027–2028.[117]
Cosmic Explorer
A design for a larger facility with longer arms is called "Cosmic Explorer". This is based on the LIGO Voyager technology, has a similar LIGO-type L-shape geometry but with 40 km arms. The facility is currently planned to be on the surface. It has a higher sensitivity than Einstein Telescope for frequencies beyond 10 Hz, but lower sensitivity under 10 Hz.[116]
See also
- BlackGEM
- Einstein Telescope, a European third-generation gravitational wave detector
- Einstein@Home, a volunteer distributed computing program one can download in order to help the LIGO/GEO teams analyze their data
- GEO600, a gravitational wave detector located in Hannover, Germany
- Holometer
- North American Nanohertz Observatory for Gravitational Waves
- Richard A. Isaacson
- PyCBC, an open source software package to help analyze LIGO data
- Tests of general relativity
- Virgo interferometer, an interferometer located close to Pisa, Italy
- Laser Interferometer Space Antenna (LISA)
- LISA Pathfinder
- Taiji Program in Space, a space-based Chinese gravitational wave detector
Notes
- doi:10.1063/1.882861.
- ^ "Facts". LIGO. Archived from the original on 4 July 2017. Retrieved 24 August 2017.
This is equivalent to measuring the distance from Earth to the nearest star to an accuracy smaller than the width of a human hair!
(that is, to Proxima Centauri at 4.0208×1013 km). - ^ "LIGO Lab Caltech MIT". Retrieved 24 June 2016.
- ^ "LIGO MIT". Retrieved 24 June 2016.
- ^ "Major research project to detect gravitational waves is underway". University of Birmingham News. University of Birmingham. Retrieved 28 November 2015.
- ^ Shoemaker, David (2012). "The evolution of Advanced LIGO" (PDF). LIGO Magazine (1): 8.
- ^ "Revolutionary Grassroots Astrophysics Project "Einstein@Home" Goes Live". Retrieved 3 March 2016.
- ^ "LSC/Virgo Census". myLIGO. Retrieved 28 November 2015.
- ^ PMID 26381963
- ^ "BOINCstats project statistics". Retrieved 14 December 2016.
- ^ Larger physics projects in the United States, such as Fermilab, have traditionally been funded by the Department of Energy.
- ^ "LIGO: The Search for Gravitational Waves". www.nsf.gov. National Science Foundation. Archived from the original on 15 September 2016. Retrieved 3 September 2018.
- ^ "The Nobel Prize in Physics 2017". Nobel Foundation.
- ^ "LSC News".
- ^ a b "LSC News".
- S2CID 119366083.
- ^ LIGO (1 November 2019). "Welcome to O3b!". @ligo. Retrieved 11 November 2019.
- ^ a b c "LIGO Suspends Third Observing Run (O3)". 26 March 2020. Retrieved 15 July 2020.
- ^ a b c "Gravitational-Wave Observatory Status". Gravitational Wave Open Science Center. 24 May 2023. Retrieved 25 May 2023.
- S2CID 258899900.
- ^ "LIGO, VIRGO AND KAGRA OBSERVING RUN PLANS". Retrieved 14 December 2021.
- ^ ISBN 978-0-309-09084-1.
- ^ Gertsenshtein, M.E. (1962). "Wave Resonance of Light and Gravitational Waves". Journal of Experimental and Theoretical Physics. 14: 84.
- ^ Weiss, Rainer (1972). "Electromagnetically coupled broadband gravitational wave antenna". Quarterly Progress Report of the Research Laboratory of Electronics. 105 (54): 84. Retrieved 21 February 2016.
- ^ "A brief history of LIGO" (PDF). ligo.caltech.edu. Archived from the original (PDF) on 3 July 2017. Retrieved 21 February 2016.
- ^ a b Buderi, Robert (19 September 1988). "Going after gravity: How a high-risk project got funded". The Scientist. 2 (17): 1. Retrieved 18 February 2016.
- ^ a b c Mervis, Jeffery. "Funding of two science labs receives pork barrel vs beer peer review debate". The Scientist. 5 (23). Retrieved 21 February 2016.
- ^ PMID 17831979.
- ^ "Gravitational waves detected 100 years after Einstein's prediction" (PDF). LIGO. 11 February 2016. Retrieved 11 February 2016.
- S2CID 119020354.
- ^ a b c d "Interview with Barry Barish" (PDF). Shirley Cohen. Caltech. 1998. Retrieved 21 February 2016.
- ^ a b Cook, Victor (21 September 2001). NSF Management and Oversight of LIGO. Large Facility Projects Best Practices Workshop. NSF.
- PMID 17812204.
- PMID 17776497.
- ^ Browne, Malcolm W. (30 April 1991). "Experts clash over project to detect gravity wave". New York Times. Retrieved 21 February 2016.
- PMID 17776497.
- PMID 25030149
- ^ "Gravitational wave detection a step closer with Advanced LIGO". SPIE Newsroom. Retrieved 4 January 2016.
- ^ "Daniel Sigg: The Advanced LIGO Detectors in the era of First Discoveries". SPIE Newsroom. Retrieved 9 September 2016.
- ^ Ghosh, Pallab (11 February 2016). "Einstein's gravitational waves 'seen' from black holes". BBC News. Retrieved 18 February 2016.
- ^ "Gravitational waves detected 100 years after Einstein's prediction". www.mpg.de. Max-Planck-Gelschaft. Retrieved 3 September 2018.
- ^ "LIGO Hanford's H1 Achieves Two-Hour Full Lock". February 2015. Archived from the original on 22 September 2015.
- ^ Zhang, Sarah (15 September 2015). "The Long Search for Elusive Ripples in Spacetime". Wired.
- ^ Amos, Jonathan (19 September 2015). "Advanced Ligo: Labs 'open their ears' to the cosmos". BBC News. Retrieved 19 September 2015.
- ^ a b "Planning for a bright tomorrow: prospects for gravitational-wave astronomy with Advanced LIGO and Advanced Virgo". LIGO Scientific Collaboration. 23 December 2015. Retrieved 31 December 2015.
- S2CID 124959784.
- ^ S2CID 182916902. Retrieved 11 February 2016.
- ^ New results on the Search for Gravitational Waves. CERN Colloquium. 2016.
- ^ "Fundamental Physics Prize – News". Fundamental Physics Prize (2016). Retrieved 4 May 2016.
- ^ a b Chu, Jennifer (15 June 2016). "For second time, LIGO detects gravitational waves". MIT News. MIT. Retrieved 15 June 2016.
- S2CID 206291714.
- ^ Conover, E. (1 June 2017). "LIGO snags another set of gravitational waves". Science News. Retrieved 3 June 2017.
- ^ "College of Sciences Professor Appointed to Top Role in Search for Gravitational Waves | News Center".
- ^ "GW170814 : A three-detector observation of gravitational waves from a binary black hole coalescence". Retrieved 29 September 2017.
- ^ "The Nobel Prize in Physics 2017". Nobelprize.org. Retrieved 4 October 2017.
- ^ Rincon, Paul; Amos, Jonathan (3 October 2017). "Einstein's waves win Nobel Prize". BBC News. Retrieved 3 October 2017.
- ^ Overbye, Dennis (3 October 2017). "2017 Nobel Prize in Physics Awarded to LIGO Black Hole Researchers". The New York Times. Retrieved 3 October 2017.
- ^ "LSC News" (PDF).
- ^ Moore, Christopher; Cole, Robert; Berry, Christopher (19 July 2013). "Gravitational Wave Detectors and Sources". Retrieved 20 April 2014.
- ^ "The Nobel Prize in Physics 1993: Russell A. Hulse, Joseph H. Taylor Jr". nobelprize.org.
- ^ "Obituary: Dr. Robert L. Forward". www.spaceref.com. 21 September 2002. Archived from the original on 2 September 2013. Retrieved 3 September 2018.
- ^ M.E. Gertsenshtein (1961). "Wave Resonance of Light and Gravitational Waves". JETP. 41 (1): 113–114. Archived from the original on 6 February 2016. Retrieved 19 January 2016.
- ^ Gertsenshtein, M. E.; Pustovoit, V. I. (August 1962). "On the detection of low frequency gravitational waves". JETP. 43: 605–607.
- .
- ^ "Location of the Source". Gravitational Wave Astrophysics. University of Birmingham. Archived from the original on 8 December 2015. Retrieved 28 November 2015.
- ^ "LIGO's Interferometer".
- ^ S2CID 124959784.
- ^ Thorne, Kip (2012). "Chapter 27.6: The Detection of Gravitational Waves (in "Applications of Classical Physics chapter 27: Gravitational Waves and Experimental Tests of General Relativity", Caltech lecture notes)" (PDF). Retrieved 11 February 2016.
- ^ "LIGO's Interferometer".
- ^ Doughton, Sandi (14 May 2018). "Suddenly there came a tapping: Ravens cause blips in massive physics instrument at Hanford". The Seattle Times. Retrieved 14 May 2018.
- PMID 29099225.
- ^ S2CID 24225193.
- ^ S2CID 5954627.
- ^ S2CID 23409406.
- ^ Svitil, Kathy (2 January 2008). "LIGO Sheds Light on Cosmic Event" (Press release). California Institute of Technology. Retrieved 14 February 2016.
- ^ Adhikari, Rana; Fritschel, Peter; Waldman, Sam (17 July 2006). Enhanced LIGO (PDF) (Technical report). LIGO-T060156-01-I.
- ^ Beckett, Dave (15 June 2009). "Firm Date Set for Start of S6". LIGO Laboratory News.
- S2CID 119238143.
- ^ Burtnyk, Kimberly (18 September 2015). "The Newest Search for Gravitational Waves has Begun". LIGO Scientific Collaboration. Archived from the original on 4 July 2017. Retrieved 9 September 2017.
LIGO's advanced detectors are already three times more sensitive than Initial LIGO was by the end of its observational lifetime
- S2CID 118570458.
- ^ Naeye, Robert (11 February 2016). "Gravitational Wave Detection Heralds New Era of Science". Sky and Telescope. Retrieved 11 February 2016.
- .
- ^ "Gravitational waves from black holes detected". BBC News. 11 February 2016.
- S2CID 118651851.
- ^ "VIRGO joins LIGO for the "Observation Run 2" (O2) data-taking period" (PDF). LIGO Scientific Collaboration & VIRGO collaboration. 1 August 2017. Archived from the original (PDF) on 10 October 2017. Retrieved 20 October 2017.
- ^ "Update on the start of LIGO's 3rd observing run". 24 April 2018. Retrieved 31 August 2018.
the start of O3 is currently projected to begin in early 2019. Updates will be provided once the installation phase is complete and the commissioning phase has begun. An update on the engineering run prior to O3 will be provided by late summer 2018.
- .
The bottom line is that [the sensitivity] is better than it was at the beginning of O1; we expect to get more detections.
- ^ GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs
- ^ a b Chu, Jennifer (16 October 2017). "LIGO and Virgo make first detection of gravitational waves produced by colliding neutron stars" (Press release). LIGO.
- ^ "Gravitational waves from a binary black hole merger observed by LIGO and Virgo".
- ^ "LIGO and Virgo Detect Neutron Star Smash-Ups".
- ^ "Observatory Status". LIGO. 23 March 2020. Archived from the original on 9 April 2020. Retrieved 23 June 2020.
- ^ Diego Bersanetti: Status of the Virgo gravitational-wave detector and the O3 Observing Run, EPS-HEP2019
- ^ "LIGO-Virgo network catches another neutron star collision".
- ^ "LIGO Laboratory statement on long term future observing plans". LIGO Lab. Retrieved 22 March 2022.
- ^ "IGWN | Observing Plans". Retrieved 4 March 2023.
- ^ "The future of gravitational wave astronomy" (PDF). Gravitational Waves International Committee. Archived from the original (PDF) on 30 July 2017. Retrieved 3 September 2018.
- S2CID 118583506, LIGO document P1200054-v6
- S2CID 119247573
- PMID 20798288, archived from the original(PDF) on 11 April 2013
- ^ Finn, Sam; Fritschel, Peter; Klimenko, Sergey; Raab, Fred; Sathyaprakash, B.; Saulson, Peter; Weiss, Rainer (13 May 2010), Report of the Committee to Compare the Scientific Cases for AHLV and HHLV, LIGO document T1000251-v1
- ^ U.S.-India Bilateral Cooperation on Science and Technology meeting fact sheet – dated 13 June 2012.
- ^ Memorandum to Members and Consultants of the National Science Board – dated 24 August 2012
- ^ Office of the Prime Minister of India [@PMOIndia] (17 February 2016). "Cabinet has granted 'in-principle' approval to the LIGO-India mega science proposal for research on gravitational waves" (Tweet) – via Twitter.
- ^ "First LIGO Lab Outside US To Come Up In Maharashtra's Hingoli". NDTV. 8 September 2016.
- ^ Souradeep, Tarun (18 January 2019). "LIGO-India: Origins & site search" (PDF). p. 27. Archived (PDF) from the original on 15 September 2019. Retrieved 15 September 2019.
- ^ "Cabinet clears Rs 2,600-crore LIGO-India; Observatory to come up in Maharashtra, will be part of global network". The Times of India. 7 April 2023.
- ^ "Upgraded LIGO to search for universe's most extreme events". www.nsf.gov. Retrieved 9 April 2020.
- S2CID 18460400.
- ^ Zucker, Michael E. (7 July 2016). Getting an A+: Enhancing Advanced LIGO. LIGO–DAWN Workshop II. LIGO-G1601435-v3.
- ^ Thompson, Avery (15 February 2019). "LIGO Gravitational Wave Observatory Getting $30 Million Upgrade". www.popularmechanics.com. Retrieved 17 February 2019.
- ^ Ghosh, Pallab (15 February 2019). "Black hole detectors to get big upgrade". Retrieved 17 February 2019.
- ^ "LIGO-T1800042-v5: The A+ design curve". dcc.ligo.org. Retrieved 9 April 2020.
- ^ "The Quantum Enhanced LIGO Detector Sets New Sensitivity Record".
- PMID 31868462.
- ^ a b McClelland, David; Evans, Matthew; Lantz, Brian; Martin, Ian; Quetschke, Volker; Schnabel, Roman (8 October 2015). Instrument Science White Paper (Report). LIGO Scientific Collaboration. LIGO Document T1500290-v2.
- ^ LIGO Scientific Collaboration (10 February 2015). Instrument Science White Paper (PDF) (Technical report). LIGO. LIGO-T1400316-v4. Retrieved 23 June 2020.
References
- Kip Thorne, ITP & Caltech. Spacetime Warps and the Quantum: A Glimpse of the Future. Lecture slides and audio
- Barry C. Barish, Caltech. The Detection of Gravitational Waves.Video from CERN Academic Training Lectures, 1996
- Barry C. Barish, Caltech. Einstein's Unfinished Symphony: Sounds from the Distant UniverseVideo from IHMC Florida Institute for Human Machine Cognition 2004 Evening Lecture Series.
- Rainer Weiss, Electromagnetically coupled broad-band gravitational wave antenna, MIT RLE QPR 1972
- On the detection of low frequency gravitational waves, M.E. Gertsenshtein and V.I. Pustovoit – JETP Vol. 43 pp. 605–607 (August 1962) Note: This is the first paper proposing the use of interferometers for the detection of gravitational waves.
- Wave resonance of light and gravitational waves – M.E. Gertsenshtein – JETP Vol. 41 pp. 113–114 (July 1961)
- Gravitational electromagnetic resonance, V.B. Braginskii, M.B. Mensky – GR.G. Vol. 3 No. 4 pp. 401–402 (1972)
- Gravitational radiation and the prospect of its experimental discovery, V.B. Braginsky – Usp. Fiz. Nauk Vol. 86 pp. 433–446 (July 1965). English translation: Sov. Phys. Uspekhi Vol. 8 No. 4 pp. 513–521 (1966)
- On the electromagnetic detection of gravitational waves, V.B. Braginsky, L.P. Grishchuck, A.G. Dooshkevieh, M.B. Mensky, I.D. Novikov, M.V. Sazhin and Y.B. Zeldovisch – GR.G. Vol. 11 No. 6 pp. 407–408 (1979)
- On the propagation of electromagnetic radiation in the field of a plane gravitational wave, E. Montanari – gr-qc/9806054 (11 June 1998)
Further reading
- Barish, Barry C. (2000). "The Science and Detection of Gravitational Waves" (PDF).
- Bartusiak, Marcia (2000). Einstein's unfinished symphony : listening to the sounds of space-time. Washington, DC: Joseph Henry Press. ISBN 978-0-425-18620-6.
- Saulson, Peter (1994). Fundamentals of interferometric gravitational wave detectors. Singapore River Edge, NJ: World Scientific. ISBN 978-981-02-1820-1.
- Collins, Harry M. (2004). Gravity's shadow the search for gravitational waves. Chicago: University of Chicago Press. ISBN 978-0-226-11378-4.
- Kennefick, Daniel (2007). Traveling at the speed of thought : Einstein and the quest for gravitational waves. Princeton, NJ: Princeton University Press. ISBN 978-0-691-11727-0.
- ISBN 978-0307958198
- Collins, Harry, M. (2017). Gravity's kiss: the detection of gravitational waves. Cambridge, MA & London: MIT Press. ISBN 978-0-262-03618-4.)
{{cite book}}
: CS1 maint: multiple names: authors list (link
External links
- LIGO Newsletters Excellent wide-audience newsletters published twice-yearly in March and September. From Issue 1 (September 2012) through to present day.
- LIGO Scientific Collaboration web page
- LIGO outreach webpage, with links to summaries of the Collaboration's scientific articles, written for a general public audience
- LIGO Laboratory
- LIGO News blog
- Living LIGO blog: answering questions about LIGO science and being a scientist by LIGO member Amber Stuver
- Advanced LIGO homepage
- Columbia Experimental Gravity
- American Museum of Natural History film and other materials on LIGO
- 40 m Prototype
- Earth-Motion studies A brief discussion of efforts to correct for seismic and human-related activity that contributes to the background signal of the LIGO detectors.
- Caltech's Physics 237-2002 Gravitational Waves by Kip Thorne Video plus notes: Graduate level but does not assume knowledge of General Relativity, Tensor Analysis, or Differential Geometry; Part 1: Theory (10 lectures), Part 2: Detection (9 lectures)
- Caltech Tutorial on Relativity – An extensive description of gravitational waves and their sources.
- Q&A: Rainer Weiss on LIGO's origins at news.mit.edu
- LIGO: a strong belief, 2/11/16 CERN Courier Interview with Barry Barish (18 March 2016 publication date).
- Video (3:10): LIGO Orrey (1 December 2018) on YouTube