GW170817

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GW170817
GW170817 spectrograms.svg
The GW170817 signal as measured by the LIGO and gravitational wave detectors. Image includes Virgo data despite signal being in its blind spot (and thus not present)
Event type Gravitational wave
Date144 million years ago
(detected 17 August 2017, 12:41:04.4 UTC)
Durationc. 1 minute and 40 seconds
Instrument LIGO, Virgo
Right ascension 13h 09m 48.08s [1]
Declination −23° 22′ 53.3″ [1]
Epoch J2000.0
Distance144 million ly
Redshift 0.0099
Host NGC 4993
Progenitor2 neutron stars
Other designationsGW170817
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GW170817 was a gravitational wave (GW) observed by the LIGO and Virgo detectors on 17 August 2017, originating within the shell elliptical galaxy NGC 4993, about 140 million light years away. [2] The wave was produced by the last moments of the inspiral of a binary pair of neutron stars, ending with their merger. As of December 2025, [3] it is the only GW detection to be definitively correlated with any electromagnetic observation. [1] [4]

Contents

Unlike the five prior GW detections—which were of merging black holes and thus not expected to have detectable electromagnetic signals [5] —the aftermath of this merger was seen across the electromagnetic spectrum by 70 observatories on 7 continents and in space, marking a significant breakthrough for multi-messenger astronomy. [1] The discovery and subsequent observations of GW170817 were given the Breakthrough of the Year award for 2017 by the journal Science. [6] [7]

GW170817 had an audible duration of approximately 100 seconds and exhibited the characteristic intensity and frequency expected of the inspiral of two neutron stars. Analysis of the slight variation in arrival time of the GW at the three detector locations (two LIGO and one Virgo) yielded an approximate angular direction to the source. Independently, a short gamma-ray burst (sGRB) of around 2 seconds, designated GRB 170817A, was detected by the Fermi and INTEGRAL spacecraft beginning 1.7 seconds after the GW emitted by the merger. [1] [8] [9] These detectors have very limited directional sensitivity, but indicated a large region of the sky which overlapped the gravitational wave direction. The co-occurrence confirmed a long-standing hypothesis that neutron star mergers describe an important class of sGRB progenitor event.

An intense observing campaign was prioritized, to scan the region indicated by the sGRB/GW detection for the expected emission at optical wavelengths. During this search, 11 hours after the signal, an astronomical transient SSS17a, later designated kilonova AT 2017gfo, [1] was observed in the galaxy NGC 4993 . [10] It was captured by numerous telescopes in other electromagnetic bands, from radio to X-ray wavelengths, over the following days and weeks. It was found to be a fast-moving, rapidly-cooling cloud of neutron-rich material, as expected of debris ejected from a neutron-star merger.

Announcement

It's the first time that we've observed a cataclysmic astrophysical event in both gravitational waves and electromagnetic waves—our cosmic messengers. [11]

Reitze D,LIGO executive director

The observations were officially announced on 16 October 2017 at press conferences at the National Press Club in Washington, D.C., and at the ESO headquarters in Garching bei München in Germany. [8] [9] [10]

Some information was leaked before the official announcement, beginning on 18 August 2017 when astronomer J. Craig Wheeler of the University of Texas at Austin tweeted "New LIGO. Source with optical counterpart. Blow your sox off!" [12] He later deleted the tweet and apologized for scooping the official announcement embargo. Other people followed up on the rumor, and reported that the public logs of several major telescopes listed priority interruptions in order to observe NGC 4993 , a galaxy 40  Mpc (130  Mly ) away in the Hydra constellation. [13] [14] The collaboration had earlier declined to comment on the rumors, not adding to a previous announcement that there were several triggers under analysis. [15] [16]

Gravitational wave detection

Artist's impression of the collision of two neutron stars. This is a general illustration, not specific to GW170817. (00:23 video.)

The gravitational wave signal lasted for approximately 100 seconds (much longer than the few seconds measured for binary black hole mergers) [17] starting from a frequency of 24  hertz. It covered approximately 3,000 cycles, increasing in amplitude and frequency to a few hundred hertz in the typical inspiral chirp pattern, ending with the collision received at 12:41:04.4  UTC. [4] : 2  It arrived first at the Virgo detector in Italy, then 22 milliseconds later at the LIGO-Livingston detector in Louisiana, United States, and another 3 milliseconds later at the LIGO-Hanford detector in the state of Washington, in the United States. The signal was detected and analyzed by a comparison with a prediction from general relativity defined from the post-Newtonian expansion. [1] : 3 

An automatic computer search of the LIGO-Hanford datastream triggered an alert to the LIGO team about 6 minutes after the event. The gamma-ray alert had already been issued at this point (16 seconds post-event), [18] so the timing near-coincidence was automatically flagged. The LIGO/Virgo team issued a preliminary alert (with only the crude gamma-ray position) to astronomers in the follow-up teams at 40 minutes post-event. [19] [20]

Sky localisation of the event required combining data from the three interferometers, but this was delayed by two problems. The Virgo data were delayed by a data transmission problem, and the LIGO Livingston data were contaminated by a brief burst of instrumental noise a few seconds prior to the event peak, which persisted parallel to the rising transient signal in the lowest frequencies. These required manual analysis and interpolation before the sky location could be announced about 4.5 hours after the event. [21] [20] The three detections localized the source to an area of 31 square degrees in the southern sky at 90% probability. More detailed calculations later refined the localization to within 28 square degrees. [19] [4] In particular, the absence of a clear detection by the Virgo interferometer implied that the source was localized within one of its blind spots, a constraint which reduced the search area considerably. [22]

Gamma ray detection

Artistic concept: two neutron stars merge Artist NSIllustration CREDIT NSF LIGO Sonoma State University A. Simonnet.jpg
Artistic concept: two neutron stars merge

The first electromagnetic signal detected was GRB 170817A, a short gamma-ray burst, detected 1.74±0.05 s after the merger time and lasting for about 2 seconds. [9] [13] [1] : 5 

GRB 170817A was first recorded by the Fermi Gamma-ray Space Telescope, which issued an automatic alert just 14 seconds after the detection. After the LIGO/Virgo circular 40 minutes later, manual processing of data from the INTEGRAL gamma-ray telescope retrieved independent data for the event. The difference in arrival time between Fermi and INTEGRAL helped to improve the sky localization.

This GRB was relatively faint given the proximity of the host galaxy NGC 4993 , possibly due to its jets not being pointed directly toward Earth, but rather at an angle of about 30 degrees off axis. [10] [23]

Electromagnetic follow-up

Hubble picture of NGC 4993 with inset showing GRB 170817A over 6 days. Credit: NASA and ESA NGC 4993 and GRB170817A after glow.gif
Hubble picture of NGC 4993 with inset showing GRB 170817A over 6 days. Credit: NASA and ESA
Light curves at various wavelengths of kilonova in NGC 4993 Eso1733f(1).jpg
Light curves at various wavelengths of kilonova in NGC 4993
The change in optical and near-infrared spectra by number of days after detection Eso1733j X-shooter spectra montage of kilonova in NGC4993.png
The change in optical and near-infrared spectra by number of days after detection

A series of alerts to other astronomers were issued, beginning with a report of the gamma-ray detection and single-detector LIGO trigger at 13:21 UTC, and a three-detector sky location at 17:54 UTC. [19] These prompted a massive search by many survey and robotic telescopes. In addition to the expected large size of the search area (about 150 times the area of a full moon), this search was challenging because the search area was near the Sun in the sky and thus visible for at most a few hours after dusk for any given telescope. [20]

In total six teams (One-Meter, Two Hemispheres (1M2H), [24] DLT40, VISTA, Master, DECam, and Las Cumbres Observatory (Chile)) imaged the same new source independently in a 90-minute interval. [1] : 5  The first to detect optical light associated with the collision was the 1M2H team running the Swope Supernova Survey, which found it in an image of NGC 4993 taken 10 hours and 52 minutes after the GW event [9] [1] [25] by the 1-meter diameter (3.3 ft) Swope Telescope operating in the near infrared at Las Campanas Observatory, Chile. They were also the first to announce it, naming their detection SSS17a in a circular issued 12h26m post-event. [24] The new source was later given an official International Astronomical Union (IAU) designation AT 2017gfo.

The 1M2H team surveyed all galaxies in the region of space predicted by the gravitational wave observations, and identified a single new transient. [23] [25] By identifying the host galaxy of the merger, it is possible to provide an accurate distance consistent with that based on gravitational waves alone. [1] : 5 

The detection of the optical and near-infrared source provided a huge improvement in localisation, reducing the uncertainty from several degrees to 0.0001 degree; this enabled many large ground and space telescopes to follow up the source over the following days and weeks. Within hours after localization, many additional observations were made across the infrared and visible spectrum. [25] Over the following days, the color of the optical source changed from blue to red as the source expanded and cooled. [23]

Numerous optical and infrared spectra were observed; early spectra were nearly featureless, but after a few days, broad features emerged indicative of material ejected at roughly 10 percent of light speed. There are multiple strong lines of evidence that AT 2017gfo is indeed the aftermath of GW170817. The color evolution and spectra are dramatically different from any known supernova. The distance of NGC 4993 is consistent with that independently estimated from the GW signal. No other transient has been found in the GW sky localisation region. Finally, various archive images show nothing at the location of AT 2017gfo, ruling out a foreground variable star in the Milky Way. [24]

The source was detected in the ultraviolet (but not in X-rays) 15.3 hours after the event by the Swift Gamma-Ray Burst Mission. [26] [6] After initial lack of X-ray and radio detections, the source was detected in X-rays 9 days later [27] using the Chandra X-ray Observatory, [28] [29] and 16 days later in the radio [30] using the Karl G. Jansky Very Large Array (VLA) in New Mexico. [10] More than 70 observatories covering the electromagnetic spectrum observed the source. [10]

The radio and X-ray light increased to a peak 150 days after the merger, [31] [32] diminishing afterwards. [33] Astronomers have monitored the optical afterglow of GW170817 using the Hubble Space Telescope. [34] [35] In March 2020, continued X-ray emission at 5-sigma was observed by the Chandra Observatory 940 days after the merger. [36]

Other detectors

No neutrinos consistent with the source were found in follow-up searches by the IceCube and ANTARES neutrino observatories and the Pierre Auger Observatory. [4] [1] A possible explanation for the non-detection of neutrinos is because the event was observed at a large off-axis angle and thus the outflow jet was not directed towards Earth. [37] [38]

Astrophysical origin and products

The origin and properties (masses and spins) of a double neutron star system like GW170817 are the result of a long sequence of complex binary star interactions. [39] The gravitational wave signal indicated that it was produced by the collision of two neutron stars [13] [14] [16] [40] with a total mass of 2.82+0.47
−0.09 solar masses (M☉). [4] If low spins are assumed, consistent with those observed in binary neutron stars expected to merge within (twice [a] ) the Hubble time, the total mass is 2.74+0.04
−0.01 M☉.

The masses of the progenitor stars have greater uncertainty. The chirp mass, a directly observable parameter which may be roughly equated to the geometric mean of the prior masses, was measured at 1.188+0.004
−0.002 M☉. [41] The larger progenitor (m1) has a 90% probability of being between 1.36 and 2.26 M☉, and the smaller (m2) has a 90% probability of being between 0.86 and 1.36 M☉. [41] Under the low spin assumption, the ranges are 1.36 to 1.60 M☉ for m1 and 1.17 to 1.36 M☉ for m2, inside a 12 km radius. [42]

A hypermassive neutron star was believed to have formed initially, as evidenced by the large amount of ejecta (much of which would have been trapped by an immediately forming black hole). At first, the lack of evidence for emissions being powered by neutron star spindown, which would occur for longer-surviving neutron stars, suggested it collapsed into a black hole within milliseconds. [43] However, a more detailed analysis of the GW170817 signal tail later found evidence of further features consistent with the seconds-long spindown of an intermediate or remnant hypermassive magnetar, [44] and the energy of this spindown was estimated at ≃63 Foe, equivalent to 3.5% of the mass-energy of the Sun. [45] This was below the estimated sensitivity of the LIGO search algorithms at the time. [46] This was confirmed in 2023 by a statistically independent method of analysis revealing the central engine of GRB 170817A. [47]

The short gamma-ray burst was followed over the next several months by its slower-evolving kilonova counterpart, a spherically expanding optical afterglow powered by the radioactive decay of heavy r-process nuclei produced and ejected at the initial cataclysmic instant. [48] [49] GW170817 therefore confirmed neutron star mergers to be viable sites for the r-process, where the nucleosynthesis of around half the isotopes in elements heavier than iron can occur. [10] A total of 16,000 times the mass of the Earth in heavy elements is believed to have formed, including approximately 10 Earth masses just of the two elements gold and platinum. [50] The electromagnetic emission is estimated at 0.5% of the mass-energy of the Sun. [45]

As of 2025, the precise nature of the ultimately stable compact remnant remains uncertain. [44] [36]

Scientific importance

Artist's impression of strontium emerging from a neutron star merger. Artist's impression of strontium emerging from a neutron star merger.jpg
Artist's impression of strontium emerging from a neutron star merger.

Scientific interest in the event was enormous, with dozens of preliminary papers (and almost 100  preprints [52] ) published the day of the announcement, including 8 letters in Science , [10] 6 in Nature , and 32 in a special issue of The Astrophysical Journal Letters devoted to the subject. [53] The interest and effort was global: The paper describing the multi-messenger observations [1] is coauthored by almost 4,000 astronomers (about one-third of the worldwide astronomical community) from more than 900 institutions, using more than 70 observatories on all 7 continents and in space. [12] [10]

The event provided a limit on the difference between the speed of light and that of gravity. Assuming the first photons were emitted between zero and ten seconds after peak gravitational wave emission, the difference between the speeds of gravitational and electromagnetic waves, vGW − vEM, is constrained to between −3×10−15 and +7×10−16 times the speed of light, which improves on the previous estimate by about 14 orders of magnitude. [41] [54] [b]

In addition, GW170817 allowed investigation of the equivalence principle (through Shapiro delay measurement) and Lorentz invariance. [4] The limits of possible violations of Lorentz invariance (values of 'gravity sector coefficients') are reduced by the new observations by up to ten orders of magnitude. [41]

The event also excluded some alternatives to general relativity, [55] including variants of scalar–tensor theory, [56] [57] [58] [59] [60] [61] [62] [63] Hořava–Lifshitz gravity, [59] [64] [60] Dark Matter Emulators, [65] and bimetric gravity, [66] Furthermore, an analysis published in July 2018 used GW170817 to show that gravitational waves propagate fully through the (3+1)–dimensional curved spacetime described by general relativity, ruling out hypotheses involving "leakage" into higher, non-compact spatial dimensions. [c] [67]

Gravitational wave signals such as GW170817 may be used as a standard siren to provide an independent measurement of the Hubble constant. [68] [69] An initial estimate of the constant derived from the observation is 70.0+12.0
−8.0 (km/s)/Mpc, broadly consistent with current best estimates. [68] Further studies improved the measurement to 70.3+5.3
−5.0 (km/s)/Mpc. [70] [71] [72] Together with the observation of future events of this kind, the uncertainty is expected to reach two percent within five years and one percent within ten years. [73] [74]

Electromagnetic observations help support the theory that neutron star mergers contribute to rapid neutron capture (r-process) nucleosynthesis [25] —previously assumed to be associated with supernova explosions—and are therefore the primary source of r-process elements heavier than iron, [1] including gold and platinum. [50] The first identification of r-process elements in a neutron star merger was obtained during a re-analysis of GW170817 spectra. [75] The spectra provided direct proof of strontium production during a neutron star merger. This also provided the most direct proof that neutron stars are made of neutron-rich matter. Since then, several r-process elements have been identified in the ejecta including yttrium, [76] lanthanum and cerium. [77]

GW170817 has enabled an empirical determination of the maximum mass for a neutron star, the Tolman–Oppenheimer–Volkoff limit, to be around 2.01 to 2.16 solar masses. [78] [79] In September 2018, astronomers reported related studies about possible mergers of neutron stars (NS) and white dwarfs (WD): including NS–NS, NS–WD, and WD–WD mergers. [80]

In October 2017, Stephen Hawking, in what turned out to be his last broadcast interview, discussed the overall scientific importance of GW170817. He mentioned an independent determination of cosmological distances, the formation of heavy elements, the birth of black holes, testing general relativity in the strong–field regime, and the behavior of matter at extreme densities. [81]

Retrospective comparisons

In October 2018, astronomers reported that, in retrospect, an sGRB event detected in 2015 ( GRB 150101B ) may represent an earlier case of the same astrophysics reported for GW170817. The similarities between the two events in terms of gamma ray, optical, and x-ray emissions, as well as to the nature of the associated host galaxies, were considered "striking", suggesting that the earlier event may also be the result of a neutron star merger, and that together these may signify a hitherto-unknown class of kilonova transients, making kilonovae more diverse and common in the universe than previously understood. [82] [83] [84] [85]

Later research further construed GRB 160821B—another sGRB predating GW170817—also to belong to this class, again based on afterglow resemblance to the AT 2017gfo signature. [86]

See also

Notes

  1. ↑ Without a Bayesian prior, the expected periodicity of a time series based on a single observation converges towards two times the observing period.
  2. ↑ The previous constraint on the difference between the speeds of light and gravity was about ±20%. [54]
  3. ↑ Compactified dimensions cannot be ruled out by GW studies because the fundamental diffraction limit for waves with frequencies in the tens to hundreds of Hz limits their probative resolution to scales no smaller than thousands of kilometers, leaving features below this scale unresolved.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Abbott BP, et al. (LIGO, Virgo and other collaborations) (October 2017). "Multi-messenger Observations of a Binary Neutron Star Merger" (PDF). The Astrophysical Journal . 848 (2): L12. arXiv: 1710.05833 . Bibcode:2017ApJ...848L..12A. doi: 10.3847/2041-8213/aa91c9 . The optical and near-infrared spectra over these few days provided convincing arguments that this transient was unlike any other discovered in extensive optical wide-field surveys over the past decade.
  2. ↑ Hjorth, Jens; Levan, Andrew J.; Tanvir, Nial R.; Lyman, Joe D.; Wojtak, Radosław; Schrøder, Sophie L.; Mandel, Ilya; Gall, Christa; Bruun, Sofie H. (16 October 2017). "The Distance to NGC 4993: The Host Galaxy of the Gravitational-wave Event GW170817". The Astrophysical Journal. 848 (2): L31. arXiv: 1710.05856 . Bibcode:2017ApJ...848L..31H. doi: 10.3847/2041-8213/aa9110 . hdl:2381/41880. S2CID   51812508.
  3. ↑ Kasliwal Mansi M (2025). "ZTF25abjmnps (AT2025ulz) and S250818k: A Candidate Superkilonova from a Subthreshold Subsolar Gravitational-wave Trigger". The Astrophysical Journal Letters . 995 (2): L59. arXiv: 2510.23732 . Bibcode:2025ApJ...995L..59K. doi: 10.3847/2041-8213/ae2000 .
  4. 1 2 3 4 5 6 Abbott BP, Abbott R, Abbott TD, Acernese F, Ackley K, Adams C, et al. (LIGO Scientific Collaboration & Virgo Collaboration) (October 2017). "GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral". Physical Review Letters. 119 (16) 161101. arXiv: 1710.05832 . Bibcode:2017PhRvL.119p1101A. doi: 10.1103/PhysRevLett.119.161101 . PMID   29099225.
  5. ↑ Connaughton V (2016). "Focus on electromagnetic counterparts to binary black hole mergers". The Astrophysical Journal Letters (Editorial). The follow-up observers sprang into action, not expecting to detect a signal if the gravitational radiation was indeed from a binary black-hole merger. [...] most observers and theorists agreed: the presence of at least one neutron star in the binary system was a prerequisite for the production of a circumbinary disk or neutron star ejecta, without which no electromagnetic counterpart was expected.
  6. 1 2 Cho A (December 2017). "Cosmic convergence". Science. 358 (6370): 1520–1521. Bibcode:2017Sci...358.1520C. doi:10.1126/science.358.6370.1520. PMID   29269456.
  7. ↑ "Breakthrough of the year 2017". Science | AAAS. 22 December 2017.
  8. 1 2 Overbye D (16 October 2017). "LIGO detects fierce collision of neutron stars for the first time". The New York Times . Retrieved 16 October 2017.
  9. 1 2 3 4 Krieger LM (16 October 2017). "A bright light seen across the Universe, proving Einstein right – violent collisions source of our gold, silver". The Mercury News . Retrieved 16 October 2017.
  10. 1 2 3 4 5 6 7 8 Cho A (16 October 2017). "Merging neutron stars generate gravitational waves and a celestial light show". Science . doi:10.1126/science.aar2149.
  11. ↑ "LIGO and Virgo make first detection of gravitational waves produced by colliding neutron stars". MIT News. 16 October 2017. Retrieved 23 October 2017.
  12. 1 2 Schilling G (16 October 2017). "Astronomers catch gravitational waves from colliding neutron stars". Sky & Telescope . because colliding black holes don't give off any light, you wouldn't expect any optical counterpart.
  13. 1 2 3 Castelvecchi D (August 2017). "Rumours swell over new kind of gravitational-wave sighting". Nature News . doi:10.1038/nature.2017.22482.
  14. 1 2 McKinnon M (23 August 2017). "Exclusive: We may have detected a new kind of gravitational wave". New Scientist . Retrieved 28 August 2017.
  15. ↑ "A very exciting LIGO-Virgo observing run is drawing to a close August 25". LIGO. 25 August 2017. Retrieved 29 August 2017.
  16. 1 2 Drake N (25 August 2017). "Strange stars caught wrinkling spacetime? Get the facts". National Geographic . Archived from the original on 27 August 2017. Retrieved 27 August 2017.
  17. ↑ "Variety of Gravitational Waves". LIGO Lab Caltech.
  18. ↑ "GCN notices related to Fermi-GBM alert 524666471". Gamma-ray Burst Coordinates Network. NASA Goddard Space Flight Center. 17 August 2017. Retrieved 19 October 2017.
  19. 1 2 3 "GCN circulars related to LIGO trigger G298048". Gamma-ray Burst Coordinates Network. NASA Goddard Space Flight Center. 17 August 2017. Retrieved 19 October 2017.
  20. 1 2 3 Castelvecchi D (October 2017). "Colliding stars spark rush to solve cosmic mysteries". Nature. 550 (7676): 309–310. Bibcode:2017Natur.550..309C. doi: 10.1038/550309a . PMID   29052641.
  21. ↑ Christopher B (16 October 2017). "GW170817—The pot of gold at the end of the rainbow" . Retrieved 19 October 2017.
  22. ↑ Schilling GA (January 2018). "Two massive collisions and a Nobel Prize". Sky & Telescope. 135 (1): 10.
  23. 1 2 3 Choi CQ (16 October 2017). "Gravitational waves detected from neutron star crashes: The discovery explained". Space.com . Purch Group . Retrieved 16 October 2017.
  24. 1 2 3 Ryan Foley and Enrico Ramirez-Ruiz (October 2017) GW170817/SSS17a: One-Meter, Two Hemispheres (1M2H)
  25. 1 2 3 4 Drout MR, Piro AL, Shappee BJ, Kilpatrick CD, Simon JD, Contreras C, et al. (December 2017). "Light curves of the neutron star merger GW170817/SSS17a: Implications for r-process nucleosynthesis". Science. 358 (6370): 1570–1574. arXiv: 1710.05443 . Bibcode:2017Sci...358.1570D. doi: 10.1126/science.aaq0049 . PMID   29038375.
  26. ↑ Landau E, Chou F, Washington D, Porter M (16 October 2017). "NASA missions catch first light from a gravitational-wave event". NASA . Retrieved 16 October 2017.
  27. ↑ Troja, E.; Piro, L.; van Eerten, H. (November 2017). "The X-ray counterpart to the gravitational-wave event GW170817". Nature. 551 (7678): 71–74. arXiv: 1710.05433 . Bibcode:2017Natur.551...71T. doi:10.1038/nature24290. ISSN   1476-4687. S2CID   205261229.
  28. ↑ "Chandra :: Photo Album :: GW170817 :: October 16, 2017". chandra.si.edu. Retrieved 16 August 2019.
  29. ↑ "Chandra Makes First Detection of X-rays from a Gravitational Wave Source: Interview with Chandra Scientist Eleonora Nora Troja". chandra.si.edu. Retrieved 16 August 2019.
  30. ↑ Hallinan, G.; Corsi, A. (2017). "A radio counterpart to a neutron star merger". Science. 358 (6370): 1579–1583. arXiv: 1710.05435 . Bibcode:2017Sci...358.1579H. doi:10.1126/science.aap9855. PMID   29038372. S2CID   3974441. Archived from the original on 6 June 2023. Retrieved 12 February 2023.
  31. ↑ Mooley, K. P.; Nakar, E.; Hotokezaka, K.; Hallinan, G.; Corsi, A.; Frail, D. A.; Horesh, A.; Murphy, T.; Lenc, E.; Kaplan, D. L.; De, K.; Dobie, D.; Chandra, P.; Deller, A.; Gottlieb, O.; Kasliwal, M. M.; Kulkarni, S. R.; Myers, S. T.; Nissanke, S.; Piran, T.; Lynch, C.; Bhalerao, V.; Bourke, S.; Bannister, K. W.; Singer, L. P. (20 December 2017). "A mildly relativistic wide-angle outflow in the neutron-star merger event GW170817". Nature. 554 (7691): 207–210. arXiv: 1711.11573 . doi:10.1038/nature25452. PMID   29261643.
  32. ↑ Dobie, Dougal; Kaplan, David L.; Murphy, Tara; Lenc, Emil; Mooley, Kunal P.; Lynch, Christene; Corsi, Alessandra; Frail, Dale; Kasliwal, Mansi; Hallinan, Gregg (2018). "A Turnover in the Radio Light Curve of GW170817". The Astrophysical Journal Letters. 858 (2): L15. arXiv: 1803.06853 . Bibcode:2018ApJ...858L..15D. doi: 10.3847/2041-8213/aac105 .
  33. ↑ Kaplan D, Murphy T (30 April 2018). "Signals from a spectacular neutron star merger that made gravitational waves are slowly fading away". The Conversation. Retrieved 16 August 2019.
  34. ↑ Morris A (11 September 2019). "Hubble Captures Deepest Optical Image of First Neutron Star Collision". ScienceDaily.com. Retrieved 11 September 2019.
  35. ↑ Lamb, G. P.; Lyman, J. D.; Levan, A. J.; Tanvir, N. R.; Kangas, T.; Fruchter, A. S.; Gompertz, B.; Hjorth, J.; Mandel, I.; Oates, S. R.; Steeghs, D.; Wiersema, K. (9 January 2019). "The Optical Afterglow of GW170817 at One Year Post-merger". The Astrophysical Journal. 870 (2): L15. arXiv: 1811.11491 . Bibcode:2019ApJ...870L..15L. doi: 10.3847/2041-8213/aaf96b . ISSN   2041-8213.
  36. 1 2 Troja E, Piro L, Ryan G, van Eerten H, Zhang B (18 March 2020). "ATel#13565 - GW170817: Continued X-ray emission detected with Chandra at 940 days post-merger". The Astronomer's Telegram . Retrieved 19 March 2020.
  37. ↑ Albert A, André M, Anghinolfi M, Ardid M, Aubert JJ, Aublin J, et al. (Antares Collaboration, IceCube Collaboration, Pierre Auger Collaboration, LIGO Scientific Collaboration, & Virgo Collaboration) (October 2017). "Search for high-energy neutrinos from binary neutron star merger GW170817 with ANTARES, IceCube, and the Pierre Auger Observatory". The Astrophysical Journal . 850 (2): L35. arXiv: 1710.05839 . Bibcode:2017ApJ...850L..35A. doi: 10.3847/2041-8213/aa9aed . S2CID   217180814.
  38. ↑ Bravo S (16 October 2016). "No neutrino emission from a binary neutron star merger". IceCube South Pole Neutrino Observatory . Retrieved 20 October 2017.
  39. ↑ Tauris TM, Kramer M, Freire PC, Wex N, Janka H, Langer N, et al. (13 September 2017). "Formation of Double Neutron Star Systems". The Astrophysical Journal. 846 (2): 170. arXiv: 1706.09438 . Bibcode:2017ApJ...846..170T. doi: 10.3847/1538-4357/aa7e89 . eISSN   1538-4357. S2CID   119471204.
  40. ↑ Sokol J (25 August 2017). "What happens when two neutron stars collide? Scientific revolution". Wired . Retrieved 27 August 2017.
  41. 1 2 3 4 Abbott BP, Abbott R, Abbott TD, Acernese F, Ackley K, Adams C, et al. (2017). "Gravitational waves and gamma-rays from a binary neutron star merger: GW170817 and GRB 170817A". The Astrophysical Journal Letters . 848 (2): L13. arXiv: 1710.05834 . Bibcode:2017ApJ...848L..13A. doi: 10.3847/2041-8213/aa920c .
  42. ↑ Abbott, B. P.; et al. (15 October 2018). "GW170817: Measurements of Neutron Star Radii and Equation of State". Physical Review Letters. 121 (16) 161101. arXiv: 1805.11581 . Bibcode:2018PhRvL.121p1101A. doi: 10.1103/PhysRevLett.121.161101 . PMID   30387654. constrain R1=11.9+1.4−1.4  km and R2=11.9+1.4−1.4  km at the 90% credible level
  43. ↑ Margalit B, Metzger BD (21 November 2017). "Constraining the Maximum Mass of Neutron Stars from Multi-messenger Observations of GW170817". The Astrophysical Journal Letters. 850 (2): L19. arXiv: 1710.05938 . Bibcode:2017ApJ...850L..19M. doi: 10.3847/2041-8213/aa991c .
  44. 1 2 van Putten MH, Della Valle M (January 2019). "Observational evidence for extended emission to GW170817". Monthly Notices of the Royal Astronomical Society: Letters. 482 (1): L46 –L49. arXiv: 1806.02165 . Bibcode:2019MNRAS.482L..46V. doi: 10.1093/mnrasl/sly166 . We report on a possible detection of extended emission (EE) in gravitational radiation during GRB170817A: a descending chirp with characteristic time-scale τs = 3.01±0.2 s in a (H1,L1)-spectrogram up to 700 Hz with Gaussian equivalent level of confidence greater than 3.3 σ based on causality alone following edge detection applied to (H1,L1)-spectrograms merged by frequency coincidences.
  45. 1 2 van Putten, Maurice H. P. M. (8 June 2023). "The Central Engine of GRB170817A and the Energy Budget Issue: Kerr Black Hole versus Neutron Star in a Multi-Messenger Analysis". Universe. 9 (6): 5. Bibcode:2023Univ....9..279V. doi: 10.3390/universe9060279 . direct detection of a descending chirp in gravitational radiation during GRB170817A. Starting between the time of merger and the onset of GRB170817A, its total energy output Egw = (3.5 ±1)%Mc2 ≈ 6.3 ×10↑52 erg is emitted at gravitational-wave frequencies fgw ≤700 Hz
  46. ↑ The LIGO Scientific Collaboration; the Virgo Collaboration (2018). "Search for gravitational waves from a long-lived remnant of the binary neutron star merger GW170817". The Astrophysical Journal. 875 (2): 160. arXiv: 1810.02581 . doi: 10.3847/1538-4357/ab0f3d .
  47. ↑ van Putten, M.H.P.M.; Della Valle, M. (2023). "Central engine of GRB170817A: Neutron star versus Kerr black hole based on multimessenger calorimetry and event timing". Astronomy & Astrophysics. 669: A36. arXiv: 2212.03295 . Bibcode:2023A&A...669A..36V. doi: 10.1051/0004-6361/202142974 .
  48. ↑ Sneppen, Albert; Watson, Darach; Bauswein, Andreas; Just, Oliver; Kotak, Rubina; Nakar, Ehud; Poznanski, Dovi; Sim, Stuart (February 2023). "Spherical symmetry in the kilonova AT2017gfo/GW170817". Nature. 614 (7948): 436–439. arXiv: 2302.06621 . Bibcode:2023Natur.614..436S. doi:10.1038/s41586-022-05616-x. ISSN   1476-4687. PMID   36792736. S2CID   256846834.
  49. ↑ "What happens when two neutron stars collide? A 'perfect' explosion". Washington Post. ISSN   0190-8286 . Retrieved 18 February 2023.
  50. 1 2 Berger E (16 October 2017). LIGO/Virgo Press Conference. Event occurs at 1h48m. Retrieved 29 October 2017.
  51. ↑ "First identification of a heavy element born from neutron star collision - Newly created strontium, an element used in fireworks, detected in space for the first time following observations with ESO telescope". www.eso.org. Retrieved 27 October 2019.
  52. ↑ "ArXiv.org search for GW170817" . Retrieved 18 October 2017.
  53. ↑ Berger E (16 October 2017). "Focus on the electromagnetic counterpart of the neutron star binary merger GW170817". The Astrophysical Journal Letters (Editorial). 848 (2). It is rare for the birth of a new field of astrophysics to be pinpointed to a singular event. This focus issue follows such an event – the neutron star binary merger GW170817 – marking the first joint detection and study of gravitational waves (GWs) and electromagnetic radiation (EM).
  54. 1 2 Schmidt F (18 December 2017). "Viewpoint: Reining in Alternative Gravity". Physics. 10: 134. doi: 10.1103/physics.10.134 .
  55. ↑ Kitching T (13 December 2017). "How crashing neutron stars killed off some of our best ideas about what 'dark energy' is". The Conversation– via phys.org.
  56. ↑ Lombriser L, Taylor A (28 September 2015). "Breaking a Dark Degeneracy with Gravitational Waves". Journal of Cosmology and Astroparticle Physics. 2016 (3): 031. arXiv: 1509.08458 . Bibcode:2016JCAP...03..031L. doi:10.1088/1475-7516/2016/03/031. S2CID   73517974.
  57. ↑ Lombriser L, Lima N (2017). "Challenges to self-acceleration in modified gravity from gravitational waves and large-scale structure". Phys. Lett. B. 765: 382–385. arXiv: 1602.07670 . Bibcode:2017PhLB..765..382L. doi:10.1016/j.physletb.2016.12.048. S2CID   118486016.
  58. ↑ Bettoni D, Ezquiaga JM, Hinterbichler K, Zumalacárregui M (14 April 2017). "Speed of gravitational waves and the fate of Scalar-Tensor Gravity". Physical Review D. 95 (8) 084029. arXiv: 1608.01982 . Bibcode:2017PhRvD..95h4029B. doi:10.1103/PhysRevD.95.084029. ISSN   2470-0010. S2CID   119186001.
  59. 1 2 Creminelli P, Vernizzi F (December 2017). "Dark Energy after GW170817 and GRB170817A". Physical Review Letters. 119 (25) 251302. arXiv: 1710.05877 . Bibcode:2017PhRvL.119y1302C. doi:10.1103/PhysRevLett.119.251302. PMID   29303308. S2CID   206304918.
  60. 1 2 Ezquiaga JM, Zumalacárregui M (December 2017). "Dark Energy After GW170817: Dead Ends and the Road Ahead". Physical Review Letters. 119 (25) 251304. arXiv: 1710.05901 . Bibcode:2017PhRvL.119y1304E. doi:10.1103/PhysRevLett.119.251304. PMID   29303304. S2CID   38618360.
  61. ↑ "Quest to settle riddle over Einstein's theory may soon be over". phys.org . 10 February 2017. Retrieved 29 October 2017.
  62. ↑ "Theoretical battle: Dark energy vs. modified gravity". Ars Technica . 25 February 2017. Retrieved 27 October 2017.
  63. ↑ "Gravitational waves". Science News. Retrieved 1 November 2017.
  64. ↑ Sakstein J, Jain B (December 2017). "Implications of the Neutron Star Merger GW170817 for Cosmological Scalar-Tensor Theories". Physical Review Letters. 119 (25) 251303. arXiv: 1710.05893 . Bibcode:2017PhRvL.119y1303S. doi:10.1103/PhysRevLett.119.251303. PMID   29303345. S2CID   39068360.
  65. ↑ Boran S, Desai S, Kahya E, Woodard R (2018). "GW170817 falsifies dark matter emulators". Phys. Rev. D. 97 (4) 041501. arXiv: 1710.06168 . Bibcode:2018PhRvD..97d1501B. doi:10.1103/PhysRevD.97.041501. S2CID   119468128.
  66. ↑ Baker T, Bellini E, Ferreira PG, Lagos M, Noller J, Sawicki I (December 2017). "Strong Constraints on Cosmological Gravity from GW170817 and GRB 170817A". Physical Review Letters. 119 (25) 251301. arXiv: 1710.06394 . Bibcode:2017PhRvL.119y1301B. doi:10.1103/PhysRevLett.119.251301. PMID   29303333. S2CID   36160359.
  67. ↑ Pardo, Kris; Fishbach, Maya; Holz, Daniel E.; Spergel, David N. (2018). "Limits on the number of spacetime dimensions from GW170817". Journal of Cosmology and Astroparticle Physics. 2018 (7): 048. arXiv: 1801.08160 . Bibcode:2018JCAP...07..048P. doi:10.1088/1475-7516/2018/07/048. S2CID   119197181.
  68. 1 2 Abbott BP, Abbott R, Abbott TD, Acernese F, Ackley K, Adams C, et al. (November 2017). "A gravitational-wave standard siren measurement of the Hubble constant". Nature. 551 (7678): 85–88. arXiv: 1710.05835 . Bibcode:2017Natur.551...85A. doi:10.1038/nature24471. PMID   29094696. S2CID   205261622.
  69. ↑ Scharping N (18 October 2017). "Gravitational waves show how fast the Universe is expanding". Astronomy . Retrieved 18 October 2017.
  70. ↑ Hotokezaka K, Nakar E, Gottlieb O, Nissanke S, Masuda K, Hallinan G, et al. (8 July 2019). "A Hubble constant measurement from superluminal motion of the jet in GW170817". Nature Astronomy . 3 (10): 940–944. arXiv: 1806.10596 . Bibcode:2019NatAs...3..940H. doi:10.1038/s41550-019-0820-1. hdl:2066/208868. S2CID   119547153 . Retrieved 8 July 2019.
  71. ↑ "New method may resolve difficulty in measuring universe's expansion – Neutron star mergers can provide new 'cosmic ruler'". National Radio Astronomy Observatory. 8 July 2019. Archived from the original on 8 July 2019. Retrieved 8 July 2019– via EurekAlert!.
  72. ↑ Finley D (8 July 2019). "New method may resolve difficulty in measuring Universe's expansion". National Radio Astronomy Observatory . Retrieved 8 July 2019.
  73. ↑ Lerner L (22 October 2018). "Gravitational waves could soon provide measure of universe's expansion" . Retrieved 22 October 2018– via Phys.org.
  74. ↑ Chen HY, Fishbach M, Holz DE (October 2018). "A two per cent Hubble constant measurement from standard sirens within five years". Nature. 562 (7728): 545–547. arXiv: 1712.06531 . Bibcode:2018Natur.562..545C. doi:10.1038/s41586-018-0606-0. PMID   30333628. S2CID   52987203.
  75. ↑ Watson D, Hansen CJ, Selsing J, Koch A, Malesani DB, Andersen AC, et al. (October 2019). "Identification of strontium in the merger of two neutron stars". Nature. 574 (7779): 497–500. arXiv: 1910.10510 . Bibcode:2019Natur.574..497W. doi:10.1038/s41586-019-1676-3. PMID   31645733. S2CID   204837882.
  76. ↑ Sneppen, Albert; Watson, Darach (1 July 2023). "Discovery of a 760 nm P Cygni line in AT2017gfo: Identification of yttrium in the kilonova photosphere". Astronomy & Astrophysics. 675: A194. arXiv: 2306.14942 . Bibcode:2023A&A...675A.194S. doi:10.1051/0004-6361/202346421. ISSN   0004-6361.
  77. ↑ Domoto, Nanae; Tanaka, Masaomi; Kato, Daiji; Kawaguchi, Kyohei; Hotokezaka, Kenta; Wanajo, Shinya (26 October 2022). "Lanthanide Features in Near-infrared Spectra of Kilonovae". The Astrophysical Journal. 939 (1): 8. arXiv: 2206.04232 . Bibcode:2022ApJ...939....8D. doi: 10.3847/1538-4357/ac8c36 . ISSN   0004-637X.
  78. ↑ Rezzolla, L.; Most, E. R.; Weih, L. R. (2018). "Using Gravitational-wave Observations and Quasi-universal Relations to Constrain the Maximum Mass of Neutron Stars". Astrophysical Journal. 852 (2): L25. arXiv: 1711.00314 . Bibcode:2018ApJ...852L..25R. doi: 10.3847/2041-8213/aaa401 . S2CID   119359694.
  79. ↑ Cho, Adrian (16 February 2018). "A weight limit emerges for neutron stars" . Science. 359 (6377): 724–725. Bibcode:2018Sci...359..724C. doi:10.1126/science.359.6377.724. PMID   29449468.
  80. ↑ Rueda JA, Ruffini R, Wang Y, Aimuratov Y, de Almeida UB, Bianco CL, et al. (28 September 2018). "GRB 170817A-GW170817-AT 2017gfo and the observations of NS–NS, NS–WD, and WD–WD mergers". Journal of Cosmology and Astroparticle Physics. 2018 (10): 006. arXiv: 1802.10027 . Bibcode:2018JCAP...10..006R. doi:10.1088/1475-7516/2018/10/006. S2CID   119369873.
  81. ↑ Ghosh, Pallab (26 March 2018). "Stephen Hawking's final interview: A beautiful Universe". BBC News . Retrieved 19 December 2025.
  82. ↑ "All in the family: Kin of gravitational wave source discovered – New observations suggest that kilonovae – immense cosmic explosions that produce silver, gold and platinum – may be more common than thought". University of Maryland. 16 October 2018. Archived from the original on 16 October 2018. Retrieved 17 October 2018– via EurekAlert!.
  83. ↑ Troja E, Ryan G, Piro L, van Eerten H, Cenko SB, Yoon Y, et al. (October 2018). "A luminous blue kilonova and an off-axis jet from a compact binary merger at z = 0.1341". Nature Communications. 9 (1) 4089. arXiv: 1806.10624 . Bibcode:2018NatCo...9.4089T. doi:10.1038/s41467-018-06558-7. PMC   6191439 . PMID   30327476.
  84. ↑ Mohon L (16 October 2018). "GRB 150101B: A distant cousin to GW170817". NASA . Retrieved 17 October 2018.
  85. ↑ Wall M (17 October 2018). "Powerful cosmic flash is likely another neutron-star merger". Space.com . Retrieved 17 October 2018.
  86. ↑ Troja E, Castro-Tirado AJ, Becerra González J, Hu Y, Ryan GS, Cenko SB, et al. (2019). "The afterglow and kilonova of the short GRB 160821B". Monthly Notices of the Royal Astronomical Society. 489 (2) stz2255: 2104. arXiv: 1905.01290 . Bibcode:2019MNRAS.489.2104T. doi: 10.1093/mnras/stz2255 . S2CID   145047934.
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