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

Our next LIGO Virgo KAGRA webinar will discuss tests of general relativity with #GWTC4 (papers arxiv.org/abs/2603.19019 arxiv.org/abs/2603.19020 arxiv.org/abs/2603.19021).

26 March at 13:00 UTC, with the recording on YouTube after

Register for free wisconsin-edu.zoom.us/webinar/regi...

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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

A boom in gravitational waves leaves scientists with more questions than answers: @sciam.bsky.social reports how we still have much to discover after #GWTC4

www.scientificamerican.com/article/what... by @krcallaway.bsky.social

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The universe is humming with ripples in spacetime

www.space.com/astronomy/bl... from @space.com discusses our #GWTC4

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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

Our next LIGO @egovirgo.bsky.social KAGRA webinar will introduce the analysis methods used for our #GWTC4 results (paper arxiv.org/abs/2508.18081)

19 February at 15:00 UTC, with the recording on YouTube after

Register for free wisconsin-edu.zoom.us/webinar/regi...

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Our previous webinar introduced #GWTC4 and the data from our fourth observing run. You can catch up on YouTube if you would like some background before hearing about our latest results

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bsky.app/profile/ligo...

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

Our next LIGO @egovirgo.bsky.social KAGRA webinar will introduce our latest #GWTC4 detections and discoveries (paper arxiv.org/abs/2508.18082)

Register for free wisconsin-edu.zoom.us/webinar/regi...

12 February at 15:00 UTC, with the recording on YouTube after

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Catch up on our #GWTC4 results with the recording of our webinar introducing our latest gravitational-wave catalog release and the associated data (papers arxiv.org/abs/2508.18080 and arxiv.org/abs/2508.18079)

youtu.be/fFKD-6parxY?...

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GWTC-4.0 Introduction & Open Data Webinar 13 November 2025 Webinar live from 15:00 UTC

Our next webinar will introduce our latest #GWTC4 release and the associated data (papers arxiv.org/abs/2508.18080 and arxiv.org/abs/2508.18079)

Tomorrow at 15:00 UTC, with the recording on YouTube after

Free registration wisconsin-edu.zoom.us/webinar/regi...

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A page of LIGO Magazine article "GW231123 - the most massive black hole merger yet!". The page includes the title of the article and an infographic about GW231123 in blues and yellows. The infographic displays information including the mass of the two black holes (which were 137 and 103 times the mass of our sun), the distance that the signal travelled (between 2 billion light years and 13 billion light years) and how long the signal lasted in the LIGO Livingston and LIGO Hanford detectors (0.1 seconds). Image credit: Simona J. Miller / Caltech.

The image shows a page of LIGO Magazine article "GW231123: the most massive black hole merger yet!". The page includes photos of the two authors, Debnandini Mukherjee & Tanmaya Mishra. Both of them are smiling.

#GW231123 - the most massive black hole merger yet! We also caught up with Debnandini Mukherjee and Tanmaya Mishra on what makes this observation interesting plus their experience of working on the discovery paper.

#GW10Years #GWTC4

A page of LIGO Magazine article "GWTC-4.0 Catalog Paper". The page includes an image showing the gravitational wave observations so far which are indicated by circles at different distances from a central point signifying the Earth. Image created by: Derek Davis/Rhiannon Udall/Caltech/LIGO-Virgo-KAGRA The page also includes a photo of one of the authors, Lucy Thomas.

A page of LIGO Magazine article about GWTC-4.0. The page includes a photo of one of the authors, Daniel Williams.

A page of the LIGO Magazine article about GWTC-4.0. The image at the top of the page is called the "masses in the stellar graveyard plot". It summarises the gravitational wave observations of neutron stars and black holes so far. Each object is represented by a circle and they are ordered vertically by mass. The image is full of circles representing many observations. The horizontal arrangement is purely aesthetic and appears like the spread wings of a bird. Image credit: LIGO-Virgo-KAGRA/Aaron Geller/Northwestern. The page also shows a photo of one of the authors, Michael Pürrer.

A page of the LIGO Magazine article about GWTC-4.0. The image at the top of the page shows an older version of the masses in the stellar graveyard plot from 2017. This older version has far fewer observations compared to the current version (described in another image within this post). Image credit: LIGO-Virgo/Frank Elaysky/Northwestern University.

As well as looking back at the last decade, we take a peak at some recent results with behind the scenes stories about the latest #GravitationalWave catalog with Lucy Thomas, @daniel-williams.co.uk and @michaelpuerrer.bsky.social

#GW10Years
#GWTC4

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"

#GWTC4 is the latest collection of #GravitationalWave observations. In the past decade we have gone from zero to hundreds of detections!

Learn more about our discoveries, and the experiences of the team behind #GWTC4 in @ligomagazine.bsky.social

ligo.org/wp-content/u...

#GW10Years 🔭🧪⚛️

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.

Tests of general relativity and the nature of black hole with #GW250114 is out now

GW250114 is so loud, it sometimes provides tighter constraints than all of the signals in #GWTC4 combined

Learn about all the details in our science summary ligo.org/science-summ...

📔: arxiv.org/abs/2509.08099

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It's really exciting to see this detailed investigation of the loudest signal from #GWTC4 appear on the arxiv.

Super-loud, super-clear signals like this allow us to probe fundamental physics in great depth, and this paper investigates this binary black hole with surgical precision.

Our detailed study of #GW230814 is out

arxiv.org/abs/2509.07348

We can precisely test general relativity with this loud signal. Most tests show agreement with Einstein's theory, but some…

The deviations can be explained by detector noise. Having multiple detectors is important!

🔭🧪⚛️☄️ #GWTC4

The gravitational-wave signal GW230814. The top panel shows the time-frequency representation of the signal where brighter regions indicate larger amplitude. The CWT acronym points to the method used to construct this time-frequency representation, based on the Continuous Wavelet Transform. The bottom panel shows the signal represented as a time series. The blue and purple lines show two different methods of reconstruction for the signal waveform. It is clear that the signal is a compact binary coalescence and the data are in good agreement with the reconstructions until the ringdown part. Being such a loud signal allows us to make this wonderfully precise reconstruction!

The loudest #GravitationalWave in #GWTC4 is #GW230814

Detected with only Livingston, it was still about twice as loud as GW150914!

Being loud should enable precision tests of general relativity, but with only one detector, you need to be careful with the analysis

ligo.org/science-summ...

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A grid of spectrograms for our gravitational-wave candidates. For each spectrogram, frequency is plotted horizontally and time vertically, so that a signal chirps up from low frequency to high frequency.

A family portrait of 218 gravitational-wave signal! Each observing run has its own color palette, tracing the journey from our very first detection to the latest #GWTC4

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LIGO, facing threats of closure, more than doubles its black hole haul 10 years ago, LIGO saw its first gravitational wave. After 218 detections, our view of black holes has changed forever. Can this era endure?

"10 years ago, LIGO saw its first gravitational wave. After 218 detections, our view of black holes has changed forever."

bigthink.com/starts-with-... by @startswithabang.bsky.social

#GWTC4 #O4IsHere 🔭🧪⚛️

The inferred mass distribution for black holes based upon our observations. We have used several different models to reconstruct this distribution, to test out different assumptions. The common features are a peak about 10 solar masses, more massive black holes being rarer, a bump with more black holes around 35 solar masses, and the distribution continuing to around 100 solar masses.

Having more gravitational-wave observations helps us unlock the astrophysical secrets of our sources

What have we learned about the family of black holes and neutron stars from our latest observations?

ligo.org/science-summ...

#GWTC4 🔭☄️🧪

GWTC-4.0: Updating the catalog with observations from the first part of the fourth LIGO-Virgo-KAGRA observing run – LSC – LIGO Scientific Collaboration

We have doubled the number of gravitational-wave detections. Catch up with the new discoveries with our Science Summary

ligo.org/science-summ...

🧪🔭⚛️ #GWTC4

GW Open Science Center Gravitational Wave Open Science Center

Data from our fourth observing run, and links to data releases to accompany our latest results are available from

gwosc.org

You can read more about using our data in arxiv.org/abs/2508.18079

#GWTC4 #OpenData 🧪⚛️☄️🔭🧑‍💻

A plot of component masses. As binaries have two components, we plot the mass of the more massive object on the horizontal axis, and the less massive object on the vertical axis. Our observations cover a range from one-and-a-bit solar masses to well over 100 solar masses. Most binaries have roughly equal masses, but there are some outliers, like the neutron star black hole binaries.

Our new discoveries in blue and our past ones in grey (point size indicates loudness)

We've a diverse range of sources. GW230518's source is a new neutron star black hole, GW231114's is two unequal black holes, GW231028's is BIG. The more we observe, the more surprises we find

#GWTC4 🔭⚛️☄️🧪

Spectrograms showing time on the horizontal axis and frequency on the vertical axis for a selection of gravitational-wave signals. Blue indicates little power, and yellow indicates lots of power. A signal sweeps up from low to high frequency. Some signals stand out like yellow bananas. Others are harder to spot, which is why we have detection pipelines instead of looking at the data by eye.

Spectrograms showing time on the horizontal axis and frequency on the vertical axis for a selection of gravitational-wave signals. Here, light blue tracks show the evolution of the signal from a template matched to the data. Longer signals are from lower mass sources. GW230518 is the longest, and corresponds to a neutron star black hole binary.

Visualisations of the data from our most significant new detections. These show time vs frequency: a binary signal sweeps up from low frequency to high making a chirp. The frequency evolution tells us about the masses.

Can you spot the signals? (The second version shows a track for each)

#GWTC4 🔭🧪

A spacetime waltz. Simulations from @sxs-collaboration.bsky.social consistent with our 86 most confident new detections, each showing the orbiting components and their emitted gravitational waves

www.youtube.com/watch?v=3B6W...

🎬I Markin/T Dietrich/H Pfeiffer

#GWTC4 🔭🧪⚛️☄️🐚

New results out today from LIGO (@ligo.org) - Virgo (@egovirgo.bsky.social) - KAGRA !

The latest catalogue features more than double the number of probable signals compared to the previous one!

#GWTC4 paper: arxiv.org/abs/2508.18082

Number of probable gravitational-wave detections plotted against the cumulative volume of the Universe observed. The observed volume scales with observing time and the sensitivity of our detectors, so it increases when we observe for longer or observe sources out to greater distance. We have more than half of our detections in just the first part of the fourth observing run as the detectors are much more sensitive than in previous runs. We now have over 200!

In our first 3 observing runs, we found 90 probable gravitational-wave signals. Analysis of the first part of our 4th observing run add 128 new probably signals, more than doubling our catalog! Analysis of the later parts of the run is underway

📈 arxiv.org/abs/2508.18080

#GWTC4 🔭☄️🧪⚛️

The timeline of observing runs covering a time span starting from 2015 and lasting up to the fourth observing run. The timeline ends with the first part of the observing run (O4a), the later parts (O4b and O4c) are not shown. We show the binary neutron star range during different observing periods. This is a conventional measure of detector performance, and indicates an average distance we can detect binary neutron stars to (binary black holes can be detected to much larger distances). We also show probable detections with black lines. There are so many in O4a that this looks more like a black box.

Our fourth observing run has seen some of best detector performance. This allows us to see gravitational-wave signals from more distant sources and make more detections. We are making more discoveries than ever before.

The timeline shows detections so far

📊 arxiv.org/abs/2508.18080

🔭🧪⚛️☄️ #GWTC4

Inferred properties of the 86 high-significance detections from the first part of our fourth observing run. For each detection, we show the inferred chirp mass, mass ratio, effective inspiral spin, effective precession spin and luminosity distance. There are so many results, that the plot fills two pages of our paper (this is Fig. 2). The plots are brightly coloured to help distinguish results for each signal.

You know you have a good set of results when your plot fills 2 whole pages

Here are the measured properties for our most significant new detections. We have a wide range of binary black holes and a couple of neutron star black hole binaries

📊 arxiv.org/abs/2508.18082

🔭🧪⚛️☄️ #GWTC4

New masses in the stellar graveyard plot, showing astronomical observations of black holes and neutron stars. The number of gravitational-wave observations of black holes is overwhelming. The plot is arranged to look nice, the horizontal axis has no meaning, but the vertical one shows masses. We have a significant range of masses from about 1 solar mass to over 200 solar masses for our largest merger remnant. New out today is a neutron star black hole binary GW230518_125908, as well as a lot of binary black holes.

Results from the first part of our fourth LIGO @egovirgo.bsky.social KAGRA observing run are out today!

We're pleased to share the largest catalog of gravitational-wave observations with more discoveries of black holes and neutron stars

📰 arxiv.org/abs/2508.18082

🔭🧪⚛️☄️ #GWTC4

"Where have you been all summer, Daniel?"

"You don't look like you've been sleeping well..."

This has been an exceptionally busy summer, but tomorrow it all comes to a climax. 1/7

#gravitationalWaves #LIGO #Virgo #KAGRA #GWTC4 #O4a #DataRelease 🔭