LIGO Scientific Collaboration

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Official account of the LIGO Scientific Collaboration. We detect gravitational waves! Email: questions@ligo.org

Webinar GWTC-5.0: Constraints on the Cosmic Expansion Rate and Modified Gravitational-wave Propagation 16 July 2026 from 14:00 UTC Background image: An artistic representation of a binary black hole merger by Aurore Simonnet
An artistic illustration of merging black holes. Inset: Black hole masses in mergers detected in gravitational waves. Image credit: Robert Lea/LIGO-Virgo-KAGRA/Aaron Geller/Northwestern
Portrait of Dr Romero-Shaw. She is smiling.Credit: Royal Astronomical Society/Isobel Romero-Shaw
Webinar Overview of GWTC-5.0: Introduction/Method/Results 9 July 2026 from 14:00 UTC Background image: An artistic representation of a binary black hole merger by Aurore Simonnet
Dr Glanzer receiving her Noise Slayer light sabre in her Calibration Wizard hat at the recent LIGO-Virgo-KAGRA meeting in Pisa. Image credit: Yumeng Xu
Screenshot of article. It has a headline “This Wasn't Really Something We Were Expecting To Be Able To Do”: Black Hole Collisions Can Now Be Used To “Autotune” Gravitational Wave Detectors Below is a graphic of a binary black hole binary sending out gravitational waves
Weegia adaption of the GW240925 + GW250207 inforgraphic by Karl Toland The Glasgow dialect is most distinctive
A poster in the style of an old Victorian science book showing depicting how we use astrophysical calibration to tune our detectors. The poster shows binary black holes (the source of our signals), illustrations of the gravitational-wave signals, the laser between our mirrors of our interferometer with a scale bar indicating the precision over which they need calibrating (they are really, really, really precise).
Portuguese infographic
Screenshot of a Jupyter notebook, showing Python code to reproduce one of the plots from the paper, together with discussion of the results and a link to further reading. The notebooks are included with the data release
The Autotune problem in gravitational waves: understanding astrophysical calibration with music 1. We hear an autotuned recording (detector data) and we want the original voice recording (gravitational wave). BUT 2. We don’t know the autotune settings (calibration uncertainty). 3. So we use a bunch of trial voice recordings (waveform templates) and apply various autotune settings to them to obtain a set of autotuned recordings. The best match reveals BOTH the autotune settings AND the original voice recording!
Comparison of analyses of the ringdown of GW250207. The plot shows the frequency and damping time of the ringdown signal. If results agree with our theoretical models of black holes, the contours should overlap with the black curve. The green contour does: it includes calibration uncertainty correctly. Yellow is just consistent: it does not include calibration uncertainty. The blue and red contours do not include calibration uncertainty either. The blue ones are consistent: they only use Livingston data, where there is no big calibration issue. The red contours are not at all consistent: they use Hanford data, where there was a calibration issue.
Comparison of Hanford detector calibration. The video shows the original miscalibrated data, as well as well calibrated data after fixing the issue. The video sweeps through different frequencies, so it starts at low frequencies, and as time goes on, goes to high frequencies.
Sky localisation of GW240925 (left) and GW250207 (right). The pink areas are obtained using data from the LIGO Livingston and Virgo detectors. Using the astrophysically-calibrated LIGO Hanford data, the possible source location shifts and shrinks to the purple and green areas. The grey bands show the measured time delays for each of the detector pairs. Much of the localization information comes from timing,
The probable shape of the inferred Hanford calibration error in terms of its amplitude and phase as a function of frequency. The larger the shaded region for a certain frequency, the larger our uncertainty as to what exactly the calibration error is there. The plots for GW240925 on the left show in green the results from the astrophysical calibration on the initial data, and in orange the quantified error using extra information measured in the detector (referred to as the ‘Detector Calibration’). We can see that the green-shaded region encapsulates the orange, which means we are successfully inferring the shape of the calibration error! On the right, we have the GW250207 results with only the green-shaded region as there was no extra detector information to cross-check these results with.
The gravitational-wave events GW240924 (top row) and GW250207 (bottom row) as observed by the LIGO Hanford (left column), LIGO Livingston (middle column), and Virgo (right column) observatories. The plots, called spectrograms, show the power spectrum (energy at different frequencies) as a function of time. The signals can be seen as the increase in energy over time (in seconds) and at specific frequencies (in hertz), represented by green and yellow bands. Their shape follows the characteristic chirp pattern produced by gravitational-wave signals. The thickness and brightness of GW250207 shows just how loud it was!
Webinar GWTC-4.0: Tests of General Relativity 26 March 2026 from 13:00 UTC Background image: An artistic representation of a binary black hole merger by Aurore Simonnet
The origins of gravitational waves. An illustration showing how a coalescing binary produces a signal. First a long inspiral, then an intense merger, finally a decaying ringdown. By Lucy Reading-Ikkanda
Webinar GWTC-4.0: Methods for Identifying and Characterizing Gravitational-wave Transients 19 February 2026 from 15:00 UTC Background image: An artistic representation of a binary black hole merger by Aurore Simonnet
I Heart gravitational waves + you. Happy Valentine's Day! The heart outline is part of a plot showing the chirp of GW150914. Credit: Zane Zocher, LIGO Hanford.
The cover of Physical Review Letters Volume 116, Number 6 featuring a cover image representing our paper: a diagram of a binary black hole coalescence over the data from our two observatories.
A photo showing 4 cakes, decorated with the theme of gravitational waves: two cakes depict a gravitational wave black hole merger, one cake depicts a celebrating GW150914 black hole (wearing a party hat!), and one writes "10 anni di onde gravitazionali" - 10 years of gravitational waves.
Article screenshot: LIGO Legacy: 10 incredible gravitational wave breakthroughs to celebrate observatory's landmark 2015 find By Robert Lea published September 14, 2025 A lot has happened in gravitational-wave astronomy over the past decade. An illustration of binary black holes ringing space-time with gravitational waves (Image credit: LIGO/T. Pyle)
LIGO Detects Gravitational Waves from Merging Black Holes Illustration Credit: LIGO, NSF, Aurore Simonnet (Sonoma State U.) Explanation: Gravitational radiation has been directly detected. The first-ever detection was made by both facilities of the Laser Interferometer Gravitational-Wave Observatory (LIGO) in Washington and Louisiana simultaneously last September. After numerous consistency checks, the resulting 5-sigma discovery was published today. The measured gravitational waves match those expected from two large black holes merging after a death spiral in a distant galaxy, with the resulting new black hole momentarily vibrating in a rapid ringdown. A phenomenon predicted by Einstein, the historic discovery confirms a cornerstone of humanity's understanding of gravity and basic physics. It is also the most direct detection of black holes ever. The featured illustration depicts the two merging black holes with the signal strength of the two detectors over 0.3 seconds superimposed across the bottom. Expected future detections by Advanced LIGO and other gravitational wave detectors may not only confirm the spectacular nature of this measurement but hold tremendous promise of giving humanity a new way to see and explore our universe.
Webinar GWTC-4.0: Updating the Gravitational-Wave Transient Catalog with Observations from the First Part of the Fourth LIGO-Virgo-KAGRA Observing Run 12 February 2026 from 15:00 UTC Background image: An artistic representation of a binary black hole merger by Aurore Simonnet
Fig. 6 of GWTC-4.0 paper. Spin disks for a selection of new detections. This show the probability distributions for spin magnitude and orientation for a few of the more interesting results.
A headshot of Amanda smiling in front of a wood panelled wall. Amanda has long dark curly hair with pink highlights, light skin, and is wearing a white blouse with black flowers on it.
Dr. Jane Glanzer smiling.
A cumulative detection plot, including significant candidate events from O4a, O4b, and O4c. There were a totla of 3 probable canddiates following O1, 11 following O2, 90 following O3, and 218 following O4a. There were 165 significant candidates in O4b and 68 in O4c. The total is almost 400. From O1 through O4a, the counts refer to the detected gravitational-wave events that are included in the GWTC papers. In contrast, the counts for O4b and O4c refer to candidate events for which a significant low-latency alert was issued and that were not subsequently retracted. The O4c data collection period is divided into two segments: January 28 April 1, 2025 and June 11 November 18, 2025. These segments are distinguished in the figure by different fill colors: the first is represented in dark blue, and the second in light blue. The intervening gap is omitted from the figure.
In Japan, KAGRA staff gathered in the control room to celebrate the end of O4. This was the first run that KAGRA took science data simultaneously with Virgo and LIGO.
GWTC-4.0 Introduction & Open Data Webinar 13 November 2025 Webinar live from 15:00 UTC
Screenshot of the arXiv page GW241011 and GW241110: Exploring Binary Formation and Fundamental Physics with Asymmetric, High-Spin Black Hole Coalescence We report the observation of gravitational waves from two binary black hole coalescences during the fourth observing run of the LIGO--Virgo--KAGRA detector network, GW241011 and GW241110. The sources of these two signals are characterized by rapid and precisely measured primary spins, non-negligible spin--orbit misalignment, and unequal mass ratios between their constituent black holes. These properties are characteristic of binaries in which the more massive object was itself formed from a previous binary black hole merger, and suggest that the sources of GW241011 and GW241110 may have formed in dense stellar environments in which repeated mergers can take place. As the third loudest gravitational-wave event published to date, with a median network signal-to-noise ratio of 36.0, GW241011 furthermore yields stringent constraints on the Kerr nature of black holes, the multipolar structure of gravitational-wave generation, and the existence of ultralight bosons within the mass range 10−13--10−12 eV. arXiv:2510.26931 [astro-ph.HE]
The gravitational wave signals: the amplitude of the data over time in a combination of the LIGO Hanford, LIGO Livingston and Virgo detectors for GW241011 (left; Hanford and Virgo) and GW241110 (right; Hanford and Livingston). The merger time of the events is at time = 0.
Plots showing how the new detection compare to our previous observations. The top panel shows all the events from the LVK’s most recently published catalog, GWTC-4.0, and our two new events GW241011 and GW241110 ordered by the primary spin projected in the direction of the spin of the orbital plane — in other words, how aligned the primary black hole’s spin direction is with the binary system’s orbit direction. Values greater than zero means the black hole is aligned with the spin of the orbit, whereas less than zero means the system is anti-aligned. The bottom panel shows the distribution of primary mass (the mass of the larger black hole) in solar masses and the mass ratio of the black hole pair for all events from GWTC-4.0 including our new events.
Infographic about GW241011 and GW241110 GW241011's source contained black holes about 13 and 8 times the mass of our Sun. The spin of the bigger black hole is high and bear aligned with the orbit. GW241110's source contained black holes about 17 and 8 times the mass of our Sun. The spin of the larger black hole is high and near anti-aligned with the orbit. Credit: Shanika Galaudage/Northwestern University/Adler Planetarium
Screenshot: 1. Proving Einstein right! The first gravitational wave detection. On Sept. 14, 2015, ripples in space-time washed over Earth that were generated by the merger of two black holes, each with a mass of around 30 times that of the sun. This signal, which would come to be known as GW150914 (GW for "gravitational wave" and the following numbers for the date of measurement), had been traveling to our planet for 1.4 billion years. GW150914's arrival and detection confirmed a theory that was first proposed a century earlier by arguably history's most famous physicist, Albert Einstein, in his 1915 theory of gravity, general relativity.
This artwork imagines the ultimate front-row seat for GW250114, a powerful collision between two black holes observed in gravitational waves by the US National Science Foundation LIGO. It depicts the view from one of the black holes as it spirals toward its cosmic partner.
An intricate arrangements of brownies representing the various optical components of the LIGO interferometers. It is surprising complicated. Candles in the shape of 10 are to the side.
Chocolate cupcakes in the shape of a gravitational-wave signal. Is this a binary merger? It looks like it would have a high mass source?
A chocolate cake covered with chocolate shavings, decorated a variety of chocolate sphere representing our black hole observations. There are birthday candles in the shape of 1 and 0 (make a wish!)
A sheet cake decorated with "Happy 10 Birthday GW150914", confetti, balloons, a binary black hole, and the data from our first detection, as well as the OzGrav logo. It is edged with some creamy frosting.
Louis Dartez receiving his LIGO Calibration Wizard hat at the September 2025 LIGO-Virgo-KAGRA meeting from Jess McIver. The hat is a traditional pointy blue hat, but is covered with images of lasers.
Screenshot of GWOSC page. This includes information on the detection, links to data, spectrogram plots, and parameter estimation results giving source parameters inferred with different waveform models
NY Times headline: "Happy Birthday, LIGO. Now Drop Dead. Ten years ago, astronomers made an epic discovery with the Laser Interferometer Gravitational-Wave Observatory. Cosmology hasn’t been the same since, and it might not stay that way much longer." Underneath, an artistic representation of two black holes orbiting each other.
Photo of Sir Jim smiling. He is wearing his usual round glasses, and a rather snazzy tie with a print of aeroplanes.
The evolution of gravitational-wave science (a colorful timeline) Starting with theoretical work in the 1910s for the form of the waves, then work in the 1950s to show the waves were real. IN 1978s Hulse and Taylor discovery the binary pulsar, showing evidence for gravitational-wave emission. Work on early detectors went through the 1980s and 1990s, with initial LIGO and Virgo operating together in the 2000s. The advanced detectors followed with development in the 2010s. The first observation came in 2015! We now have hundreds of detections.
Screen shot of the LIGO Magazine, headline "A one-stop shop for new gravitational waves". The page includes a graphic showing mass, signal-to-noise ratio (SNR), and luminosity distance of gravitational wave events. Also known as the “petri dish plot”. The results from the latest observing period (O4a) have the most events, the ones at greatest distance and the ones with highest SNR. Text of the article reads "This catalog’s publication is an incredibly important moment for the LVK collaboration and for me personally. It is the culmination of more than two years of work from many hundreds of people who, at every stage of identifying and investigating the gravitational waves, have worked together in sync to make this amazing achievement happen"
Screenshot of the LIGO Magazine, showing a colorful numerical relativity simulation of GW150915 along with the headline "A perfect source: Timeline of GW150914".
A cartoon of a 10th birthday cake being swallowed by a black hole.
Cover image for the LIGO Magazine: "10 years of gravitational wave astronomy" showing data for GW150914 and GW231123
Front cover of issue 27 of the LIGO Magazine 10 years of graviational wave astronomy GW150914 to GW231123: a signal that changed to world (p 6) GW231123: the most massive black hole merger yet! (p 24) GWTC-4.0 cataglgue paper (p 20) GW observatories of the future (p 34) Climate change conversations: Fossil-free supercomputing (p 40)
A portrait of Einstein and Hawking with a binary black hole in between. It is rather dramatic, and shows cool light-bending effects.
Artistic interpretation of a binary black hole. It is probably more colourful than the real thing. Credit: Aurore Simonnet (SSU/EdEon)
"The measurements we are making now remain the most precise measurements humans have ever achieved in any field of science and engineering." - Prof Vicky Kalogera
Comparison of a Hubble Space Telescope image and a much clearer JWST image of the same patch of sky. Progress in telescopes has enabled many astronomical discoveries. Similarly, comparison of our detection of GW150914 in 2015 and GW250115 in 2025. The latter is much, much clearer, enabling precision tests of gravity and the nature of black holes as well as measurements of the source properties.
A black hole hunting machine New black hole merger bolsters Hawking area theorem Physicists spliced merger's gravitational signal into isolated frequencies to determine surface area
A cartoon showing the area of the two progenitor black holes inferred from the inspiral part of the signal is less than the area of the final black hole inferred from the ringdown part of the signal. Credit: L. Reading-Ikkanda/Simons Foundation
Gizmondo headline "LIGO’s Sharpest Detection Yet Confirms Famous Stephen Hawking Theory" above an artistic image of a binary black hole merger in a soothing blue by Maggie Chiang for Simons Foundation
A comparison of GW250114 with our first detection GW150914. The stretching of space in the new black hole merger (top) is similar to that in the first one ever spotted (bottom), but because of reductions in the noise in the detectors, the signal stands out far more clearly. Graphic by C. Bickel/Science. Data from us
Measured 90% upper bounds on possible deviations from general relativity in the post-Newtonian expansion of the inspiral phase of the gravitational-wave signal. The post-Newtonian framework describes the inspiral phase as a series in powers of the binary’s orbital velocity (v/c), where c is the speed of light, with each coefficient predicted uniquely by general relativity. For the (v/c)¹ term, general relativity predicts the coefficient to be exactly zero, so the bound corresponds to an absolute deviation; for all other orders, bounds represent fractional deviations. The blue stars show the constraints measured from GW250114. For comparison, light red bands mark results from individual GWTC-4.0 signals, and red squares indicate combined catalog constraints from 17 events. Across all post-Newtonian orders, the measurements from GW250114 place upper bounds that are two to three times more stringent than those obtained by combining multiple events.