LIGO and Virgo Collaborations preparing a brief guide to LIGO detector noise and extraction of gravitational-wave signals
Recent claims in a preprint by Creswell et al. of puzzling correlations in LIGO data have broadened interest in understanding the publicly available LIGO data around the times of the detected gravitational-wave events. We see that the features presented in Creswell et al. arose from misunderstandings of public data products. The LIGO Scientific Collaboration and Virgo Collaboration (LVC) have full confidence in our published results, and we are preparing a paper in which we will provide more details about LIGO detector noise properties and the data analysis techniques used by the LVC to detect gravitational-wave signals and infer their waveforms.
July 2017 update on LIGO's second observing run
7 July 2017 -- The second Advanced LIGO run began on November 30, 2016 and is scheduled to end on August 25, 2017. The run was suspended on May 8 for some in-vacuum commissioning activities at both sites; it resumed on May 26 at LIGO Livingston Observatory and on June 8 at LIGO Hanford Observatory. As of June 23, approximately 81 days of Hanford-Livingston coincident science data have been collected. The average reach of the LIGO network for binary merger events has been around 70 Mpc for 1.4+1.4 Msun, 300 Mpc for 10+10 Msun and 700 Mpc for 30+30 Msun mergers, with relative variations in time of the order of 10%.
As of June 23, 8 triggers, identified by online analysis using a loose false-alarm-rate threshold of one per month, have been identified and shared with astronomers who have signed memoranda of understanding with LIGO and Virgo for electromagnetic followup. One of these triggers has been confirmed by offline analysis, given the name GW170104, and published on June 1. A thorough investigation of the data and offline analysis are in progress; results will be shared when available.
Advanced Virgo has joined the network for few days in June in engineering mode, performing full tests in preparation for the triple-observing run planned for later this summer.
First triple lock of LIGO and Virgo interferometers
17 June 2017 -- For the first time, all three second generation interferometers---LIGO Hanford, LIGO Livingston, and Virgo---are simultaneously in a locked state. (When an interferometer is "locked" it means that an optical resonance is set up in the arm cavities and is producing a stable interference pattern at the photodetector.) Virgo is joining in an engineering mode, in preparation for the full triple-observing mode planned for later this summer. Congratulations, Virgo!
Image Credit: Virgo Collaboration
LIGO Detects Gravitational Waves for Third Time
1 Jun 2017 -- The LIGO Scientific Collaboration and the Virgo collaboration confirmed a third gravitational wave event in data from the Advanced LIGO detectors in Livingston, Louisiana, and Hanford, Washington, USA.
The detected waves—observed on January 4th, 2017 at 10:11:58.6 UTC (5:12AM EST) —were produced by a binary black hole system. Stellar-mass black holes with 31.2 and 19.4 solar masses merged to produce a spinning black hole of 48.7 solar masses. The detected signal is completely consistent with the predictions of general relativity.
Image credit: LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)
LSC elects David Shoemaker as new spokesperson
29 March 2017 -- David Shoemaker, MIT senior research scientist, was elected spokesperson of the LIGO Scientific Collaboration. Shoemaker was the leader of the Advanced LIGO project. He succeeds outgoing spokesperson Gabriela González. More information can be found on the MIT press release.
Image Credit: Bryce Vickmark
LSC mourns the passing of LIGO co-founder Ronald Drever
9 March 2017 -- Ronald William Prest Drever, co-founder of LIGO and emeritus professor of physics at Caltech, passed away on 7 March 2017 at the age of 85. A full obituary can be found on the Caltech website, the Scotsman, and Science Magazine.
Image Credit: Caltech Archives
LIGO Leadership recognized by National Academy of Sciences and American Astronomical Society prizes; LIGO Team recognized by Royal Astronomical Society
27 January 2017 -- Present and past leaders of the LIGO Laboratory and the LIGO Scientific Collaboration were recognized with major prizes by the National Academy of Sciences and the American Astronomical Society. The entire LIGO Team was recognized by the UK Royal Astronomical Society.
On January 25th the High Energy Astrophysics Division (HEAD) of the American Astronomical Society (AAS) awarded the Bruno Rossi Prize to Gabriela González and the LIGO Scientific Collaboration (LSC). The Rossi Prize is awarded annually to recognize "a significant contribution to High Energy Astrophysics, with particular emphasis on recent, original work." González is a professor of physics and astronomy at Louisiana State University (LSU) and has been the LSC spokesperson since 2011. More information about the award can be found on the AAS website.
On January 26th the National Academy of Scienes (NAS) awarded the Henry Draper Medal to Barry Barish and Stan Whitcomb, and the NAS Award for Scientific Discovery to Gabriela González, David H. Reitze, and Peter R. Saulson.
The Henry Draper Medal is awarded every four years and honors "a recent, original investigation in astronomical physics, of importance and benefit to science to merit such recognition." Barry Barish is the Linde Professor of Physics, Emeritus at the California Institute of Technology. Barish was the Principle Investigator of LIGO from 1994 to 2005, during the period of its construction and initial operation. Stan Whitcomb is the LIGO Laboratory Chief Scientist at the California Institute of Technology. Whitcomb has been working on gravitational-wave detection since 1980; he led the team that designed and commissioned the initial LIGO detectors and helped train the team that built Advanced LIGO. More information about the award can be found on the website for the 2017 NAS Henry Draper Medal.
The NAS Award for Scientific Discovery is presented every two years for "an accomplishment or discovery in basic research, achieved within the previous five years, that is expected to have a significant impact on one or more of the following fields: astronomy, biochemistry, biophysics, chemistry, materials science, or physics." The 2017 award recognizes the first three elected spokespersons of the LIGO Scientific Collaboration: Saulson, Reitze, and González. (Rai Weiss was the first spokesperson of the LSC). Peter Saulson is the Martin A. Pomerantz ’37 Professor of Physics at Syracuse University. David Reitze is the Executive Director of LIGO Laboratory at Caltech and a Professor of Physics at the University of Florida. The award recognizes the role of the current and past spokespersons in leading the LIGO team to the first direct detections of gravitational waves in 2015. More information can be found on the webpage for the 2017 NAS Award for Scientific Discovery.
On January 13, 2017 the UK Royal Astronomical Society (RAS) awarded their 2017 Group Achievement Award in Astronomy to the LIGO Team, in recognition of the first direct detection of gravitational waves. More information can be found at the RAS news release.
LIGO to be honored at Special Breakthrough Prize Ceremony on December 4th; watch LIVE
3 December 2016 -- On Sunday, December 4th, at 10ET/9c, tune into the National Geographic channel to watch LIGO and other remarkable scientists and mathematicians receive this year’s Breakthrough Prizes. The star-studded ceremony will be hosted by Morgan Freeman, and will include a performance by Alicia Keys.
In May of this year, LIGO was named the recipient of a Special Breakthrough Prize in Fundamental Physics. This “Special” prize (separate from the 'regular' Breakthrough Prize) can be awarded at any time by the selection committee, which includes an impressive array of internationally renowned scientists. Previous winners of the Special Prize include seven leaders of the Large Hadron Collider teams that discovered the Higgs Boson. This time, the $3 million dollar prize acknowledges LIGO’s historic detection of gravitational waves and the subsequent empirical confirmation of the most difficult-to-detect predication of general relativity. The prize will be shared between LIGO founders Ronald W. P. Drever, Kip S. Thorne and Rainer Weiss, and 1012 contributors to the discovery. The Breakthrough Prize in Fundamental Physics was founded in 2012 by Yuri Milner to recognize those individuals who have made profound contributions to human knowledge.
Kip Thorne and Rai Weiss will be on hand to accept the award on behalf of the LIGO Scientific Collaboration. If you can’t tune in live this Sunday, Fox Network and NatGeo stations will re-air a one-hour version of the ceremony on Sunday, Dec. 18, at 7:00-8:00 PM ET/PTth. For more details on the Breakthrough Prize and on how to watch this event live, check out these websites:
The Ceremony: https://breakthroughprize.org/News/33
LIGO Named as Special Prize Winner: https://breakthroughprize.org/News/32
Breakthrough Prize website: https://breakthroughprize.org
LIGO Resumes Search for Gravitational Waves
30 November 2016 -- After a series of upgrades, the twin detectors of LIGO, the Laser Interferometer Gravitational-wave Observatory, have turned back on and resumed their search for ripples in the fabric of space and time known as gravitational waves. LIGO transitioned from engineering test runs to science observations at 8 a.m. Pacific Standard Time on November 30.
On February 11, 2016, the LIGO Scientific Collaboration (LSC) and the Virgo Collaboration announced that LIGO had made the first-ever direct observation of gravitational waves. The waves were generated by a tremendously powerful collision of two black holes 1.3 billion light-years away and were recorded by both of LIGO's detectors—one in Hanford, Washington, and the other in Livingston, Louisiana. A second gravitational-wave detection by LIGO was announced on June 15, 2016, also from merging black holes.
The initial detections were made during LIGO's first run after undergoing major technical upgrades in a program called Advanced LIGO. That run lasted from September 2015 to January 2016. Since then, engineers and scientists have been evaluating LIGO's performance and making improvements to its lasers, electronics, and optics—resulting in an overall increase in LIGO's sensitivity.
"For our first run, we made two confirmed detections of black-hole mergers in four months," says Caltech's Dave Reitze, executive director of the LIGO Laboratory, which operates the LIGO observatories. "With our improved sensitivity, and a longer observing period, we will likely observe even more black-hole mergers in the coming run and further enhance our knowledge of black-hole dynamics. We are only just now, thanks to LIGO, learning about how often events like these occur."
The Livingston detector now has about a 25 percent greater sensitivity—or range for detecting gravitational waves from binary black holes—than during the first observing run. That means it can see black-hole mergers at further distances than before, and therefore should see more mergers than before. The sensitivity for the Hanford detector is similar to that of the first observing run.
"The Livingston detector has improved sensitivity for lower gravitational-wave frequencies, below about 100 hertz, primarily as the result of reducing the level of scattered light, which can be a pernicious source of noise in the interferometers," says Peter Fritschel, the associate director for LIGO at MIT and LIGO's chief detector scientist. "This is important for detecting massive systems like the merger of two black holes. We are confident that we'll see more black-hole mergers."
"LIGO Hanford scientists and engineers have successfully increased the power into the interferometer, and improved the stability of the detector," says Caltech's Mike Landry, the head of LIGO Hanford Observatory. "Significant progress has been made for the future utilization of still higher power, which will ultimately lead to improved sensitivity in future runs. Furthermore, with the addition of specialized sensors called balance-beam tilt meters in the corner and end stations, the detector is now more stable against wind and low-frequency seismic motion, thereby increasing the amount of time the detector can be in observing mode."
The LIGO team will continue to improve the observatories' sensitivities over the coming years, with increases planned for each successive observing run. As more black-hole mergers are detected by LIGO, scientists will start to get their first real understanding of black-hole pairs in the universe—including their population numbers, masses, and spin rates. LIGO may also detect the merger of neutron stars—the dense cores of exploded stars. Knowledge of both black-hole and neutron-star mergers will improve our understanding of stellar evolution and death.
"LIGO's scientific and operational staff have been working hard for the past year and are enthusiastic to restart round-the-clock observations. We are as curious as the rest of the world about what nature will send our way this year," says LIGO Livingston Observatory head Joe Giaime of Caltech and Louisiana State University.
Caltech and MIT conceived of, built, and operate the LIGO Observatories, with funding provided by the National Science Foundation (NSF). The Advanced LIGO detector was constructed by Caltech and MIT with funding from NSF and contributions from LSC institutions worldwide, including the Max Planck Society in Germany, the Science and Technology Facilities Council (STFC) in the U.K., and the Australian Research Council, among many others.
LIGO research is carried out by the international LIGO Scientific Collaboration (which includes the GEO Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration in Europe.
GravitySpy, A Crowdsourcing Tool for Finding Glitches in LIGO Data, Is Launched
12 October 2016 -- Gravity Spy, a crowdsourcing tool for finding and analyzing glitches in LIGO data, has been publicly launched today. Glitches, or noise, in the LIGO data are a byproduct of very high sensitivity of LIGO instruments. The presence of these non-gravitational-wave disturbances in the data can obscure or mimic true gravitational-wave signals. The origin of some glitches is well-understood, while others remain a mystery. The rates at which the glitches occur vary depending on what's going on with the detectors and their environments. At their highest rates, glitches happen at 3x/sec. At such rates and with more than 2 dozen types of glitches observed so far, it takes an enourmous amount of data processing to sort out and classify them. To facilitate this process, the Gravity Spy tool is crowdsourcing the glitch identification to citizen scientists. With each new classification, LIGO will move closer and closer to discovering new gravitational-wave signals by identifying possible noise patterns in its data and filtering them out. Read more, and sign up, at the Gravity Spy website.
The Gravity Spy tool is a result of collaborative efforts of several LSC groups. The Gravity Spy team consists of LIGO researchers at the Center for Interdisciplinary Exploration and Research in Astronomy (CIERA) at Northwestern University, LIGO researchers at Caltech, machine learning researchers at Northwestern University, crowd-sourced science researchers at Syracuse University, and Zooniverse web developers.
LIGO Celebrates First Anniversary of Historic Gravitational Wave Detection
14 September 2016 -- Today LIGO celebrates the 1st anniversary of its gravitational-wave detection. Read this article about how this historic discovery was made, and about its significance for the future of gravitational-wave astronomy, at the LIGO Lab website.
Image: A. Simonnet
Advanced LIGO Engineering Team Wins OSA's 2016 Paul F. Forman Award
7 September 2016 -- The Advanced LIGO Engineering Team has been awarded the Paul F. Forman Team Engineering Excellence Award from the Optical Society. This award recognizes technical achievements such as product engineering, process, software and patent development, as well as contributions to society such as engineering education, publication and management, and furthering public appreciation of optical engineering. In addition to members of the LIGO Laboratory at all 4 locations, the team includes individuals from Albert Einstein Institute and Laser Zentrum Hannover, Glasgow University, Rutherford Appleton Laboratory, Standford University, and University of Florida. (See the full list of Advanced LIGO awardees.) The award will be presented at the Frontiers in Optics, the 100th OSA meeting that will take place in October 2016, followed by an article in Optics & Photonics News on the winners. LIGO Chief Engineer Dennis Coyne and LIGO Senior Optical Engineer GariLynn Billingsley will collect the award on behalf of the Advanced LIGO team. Congratulations to all the team members!
LSC Congratulates the LISA Pathfinder Team on the Satellite Mission Success
6 September 2016 -- The LIGO Scientific Collaboration would like to congratulate the LISA Pathfinder team on the fantastic success of their space satellite mission. This technology test mission has demonstrated acceleration noise at mHz frequencies which is better than required for the full LISA mission, and interferometric readout noise which far better than required. The Pathfinder triumph shows that LISA technology is sound, and paves the way towards multi-wavelength gravitational wave astronomy, as advocated in the recent US National Academy of Science "Review of Progress Toward the Decadal Survey Vision in New Worlds, New Horizons in Astronomy and Astrophysics". LISA, together with LIGO, its partners, and future ground-based detectors, will make it possible to "listen" to the universe over a frequency band that is more than 30 octaves wide. We can hardly wait to discover this unknown world!
Image: Artist's impression of the LISA Pathfinder. Credit: ESA
Gravitational Waves Detected from Second Pair of Colliding Black Holes
15 June 2016 -- The LIGO Scientific Collaboration and the Virgo collaboration identify a second gravitational wave event in the data from Advanced LIGO detectors.
On December 26, 2015 at 03:38:53 UTC, scientists observed gravitational waves — ripples in the fabric of spacetime — for the second time. The gravitational waves were detected by both of the twin Laser Interferometer Gravitational - Wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA.
LIGO Founders Are the Winners of the 2016 Kavli Prize in Astrophysics
2 June 2016 -- Three founders of LIGO are the recipients of the prestigious Kavli Prize in Astrophysics. The Kavli Foundation announced that Ronald W.P. Drever (Caltech), Kip S. Thorne (Caltech) and Rainer Weiss (MIT) are the 2016 awardees of the $1 million prize. The prize, which is awarded every 2 years, recognizes "scientists for their seminal advances in three research areas," including Astrophysics, Kavli Prize website states. The three founders of LIGO are being honored for "their ingenuity, inspiration, intellectual leadership and tenacity [which] were the driving force behind [the] epic discovery" of gravitationa waves, the prize citation reads.
Update 6 Sep 2016: The Kavli Prize was presented to (below, l-r) Ian Drever (representing his brother Ronald); Rainer Weiss; and Kip S. Thorne by Crown Prince of Norway Haakon at a ceremony in Oslo, Norway:
Credit: The Kavli Prize.
LIGO Founders Receive The Shaw Prize in Astronomy
31 May 2016 -- The three researchers who founded LIGO have been awarded the 2016 Shaw Prize in Astronomy, The Shaw Foundation announced. Ronald W.P. Drever (Caltech), Kip S. Thorne (Caltech) and Rainer Weiss (MIT) are the recipients of the $1.2 million prize, awarded annually. According to the prize citattion, the award recognizes their collective work on "conceiving and designing the Laser Interferometer Gravitational-Wave Observatory (LIGO), whose recent direct detection of gravitational waves opens a new window in astronomy, with the first remarkable discovery being the merger of a pair of stellar mass black holes."
LIGO Members Awarded The 2016 Gruber Prize in Cosmology
4 May 2016 -- The three principal founders of LIGO, along with the entire LIGO discovery team, have been awarded The 2016 Gruber Prize in Cosmolgy, the Gruber Foundation announced.
Ronald W.P. Drever (Caltech), Kip S. Thorne (Caltech), and Rainer Weiss (MIT) will each receive a gold medal and will share a $500,000 award. The Prize citation reads: "The Gruber Foundation proudly presents the 2016 Cosmology Prize to Rainer Weiss, Kip Thorne, Ronald Drever, and the entire LIGO team for pursuing a vision to observe the universe in gravitational waves, leading to a first detection that emanated from the collision of two black holes. This remarkable event provided the first glimpse into the strong‐gravity regime of Einstein's theory of general relativity that governs the dynamics of black holes, giving direct evidence for their existence, and demonstrating that their nature is consistent with the predictions of general relativity."
LIGO Awarded Special Breakthrough Prize in Fundamental Physics
2 May 2016 -- Members of the LIGO and Virgo collaborations have been awarded a Special Breakthrough Prize in Fundamental Physics, the Prize Selection Committee announced.
The award recognizes "the scientists and engineers contributing to the momentuous detection of gravitational waves", which was announced by LIGO on Feb 11, 2016, stated the announcement by the Selection Committee.
The Special Breakthrough Prize can be awarded at any time in recognition of an exceptional scientific achievement. The $3 million prize will be shared as follows: the three LIGO founders -- Ronald W.P. Drever (Caltech); Kip S. Thorne (Caltech); and Rainer Weiss (MIT) -- will share $1 million; and the 1012 contributing scientists, engineers, and staff will share $2 million.
NSF Signs a LIGO-India MOU
31 March 2016 -- The US and India have signed a Memorandum of Understanding for establishing an advanced gravitational-wave detector in India. France A. Córdova, Director of the National Science Foundation, and representatives of India's Department of Atomic Energy and Department of Science and Technology, signed the MoU in the presence of India's Prime Minister Narendra Modi. (Image: NSF/Fleming Crim.)
From the NSF website: "Today, National Science Foundation (NSF) Director France A. Córdova signed a Memorandum of Understanding (MOU) to lead the way for establishing an advanced gravitational-wave detector in India. The MOU was also signed by representatives from India's Department of Atomic Energy and India's Department of Science and Technology."
Read the NSF Press Release.
LIGO Team Testifies Before US Congress on the Discovery
24 February 2016 -- As a follow-up to the announcement of LIGO's first observation of gravitational waves, the House Committee on Science, Space, and Technology has asked LIGO Scientific Collaboration members to testify on the discovery, its meaning for science and society, and what the future may hold. LSC members to testify at the Full House Committee Hearing were the LIGO Lab Executive Director David Reitze, the LSC Spokesperson Gabriela Gonzalez, and the LIGO MIT Director David Shoemaker. Details at house.gov.
Watch the hearing below:
17 February 2016 -- The LIGO-India project has been formally approved by the Union Cabinet. The formal approval will clear the path for funding of the LIGO-India project, as well as for other activities that are critical for the start of building a gravitational-wave detector in India.
Read an article in The Hindu.
White House Congratulates the LIGO Team
12 February 2016 -- On February 11, President Obama tweeted his congratulations to the LIGO team:
On Feb 12, 2016, John P. Holdren, Assistant to the President for Science and Technology and Director of the White House Office of Science and Technology Policy, posted a statement on the White House blog with congratulations to the LIGO team.
Read the full statement on https://www.whitehouse.gov/blog.
Gravitational Waves Detected 100 Years after Einstein's General Relativity
11 February 2016 -- For the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein's 1915 general theory of relativity and opens an unprecedented new window onto the cosmos.
Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed.
The gravitational waves were detected on September 14, 2015 at 5:51 a.m. Eastern Daylight Time (9:51 a.m. UTC) by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. The LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. The discovery, accepted for publication in the journal Physical Review Letters, was made by the LIGO Scientific Collaboration (which includes the GEO600 Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration using data from the two LIGO detectors.
LSC Statement on Harassment
16 January 2016 -- There have been recent reports of harassment involving LIGO Scientific Collaboration members, specifically involving a Caltech faculty member and a student. That faculty member is no longer a member of the LSC. As a collaboration, we will not tolerate harassment and strive to provide a supportive environment for all members of our collaboration. We practice the principles enshrined in the LSC Diversity Statement, with guidelines in https://dcc.ligo.org/LIGO-M1400285/public:
"As members of the LIGO Scientific Collaboration, we recognize the importance of diversity to enrich our research and scholarship. We pledge to provide a welcoming, inclusive environment to talented individuals regardless of characteristics such as, but not limited to, physical ability, race, ethnicity, gender, sexual orientation, economic status, or personal religious practices, and to support the professional growth of all collaboration members.
We also pledge to work to increase the numbers of women and under-represented minorities that actively participate in the LSC, to pursue recruitment, mentoring, retention and promotion of women and under-represented minority scientists and engineers and to maximize their contribution to excellence in our research. As a collaboration, we will strive to create a professional climate that encourages inclusion and that respects and values diversity."