Neutron star merger

Last updated

Artist's impression of neutron stars merging, producing gravitational waves and resulting in a kilonova Eso1733s Artist's impression of merging neutron stars.jpg
Artist's impression of neutron stars merging, producing gravitational waves and resulting in a kilonova

A neutron star merger is the stellar collision of neutron stars.

Contents

When two neutron stars fall into mutual orbit, they gradually spiral inward due to gravitational radiation. When they finally meet, their merger leads to the formation of either a more massive neutron star, or—if the mass of the remnant exceeds the Tolman–Oppenheimer–Volkoff limit—a black hole. The merger can create a magnetic field that is trillions of times stronger than that of Earth in a matter of one or two milliseconds. These events are believed to create short gamma-ray bursts. [1]

The merger of neutron stars momentarily creates an environment of such extreme neutron flux that the r-process can occur. This reaction accounts for the nucleosynthesis of around half of the isotopes in elements heavier than iron. [2]

The mergers also produce kilonovae, [3] which are transient sources of isotropic longer wave electromagnetic radiation due to the radioactive decay of heavy r-process nuclei that are produced and ejected during the merger process. [4] Kilonovae had been discussed as a possible r-process site since the reaction was first proposed in 1999, but the mechanism became widely accepted after multi-messenger event GW170817 was observed in 2017.

Observed mergers

17 August 2017: Gravitational wave (GW170817) detected from merger of two neutron stars (00:23 video; artist concept).

On 17 August 2017, the LIGO/Virgo collaboration detected GW170817, [5] a gravitational wave associated with the merger of two neutron stars in NGC 4993, an elliptical galaxy in the constellation Hydra. [6] GW170817 co-occurred with a short (roughly 2-second long) gamma-ray burst, GRB 170817A, first detected 1.7 seconds after the GW merger signal, and a visible light observational event first observed 11 hours afterwards, SSS17a. [7] [8] [9] [10] [11]

The co-occurrence of GW170817 with GRB 170817A in both space and time strongly implies that neutron star mergers create short gamma-ray bursts. The subsequent detection of Swope Supernova Survey event 2017a (SSS17a) [12] in the area where GW170817 and GRB 170817A were known to have occurred—and its having the expected characteristics of a kilonova—strongly imply that neutron star mergers are responsible for kilonovae as well. [13]

In February 2018, the Zwicky Transient Facility began to track neutron star events via gravitational wave observation, [14] as evidenced by "systematic samples of tidal disruption events". [15] Later that year, astronomers reported that GRB 150101B, a gamma-ray burst event detected in 2015, may be directly related to GW170817 and associated with the merger of two neutron stars. 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, are "striking", suggesting the two separate events may both be the result of the merger of neutron stars, and both may be a kilonova, which may be more common in the universe than previously understood, according to the researchers. [16] [17] [18] [19]

Also in October 2018, scientists presented a new way to use information from gravitational wave events (especially those involving the merger of neutron stars like GW170817) to determine the Hubble constant, which establishes the rate of expansion of the universe. [20] [21] The two earlier methods for finding the Hubble constant—one based on redshifts and another based on the cosmic distance ladder—disagree by about 10%. This difference, the Hubble tension, might be reconciled by using kilonovae as another type of standard candle. [22]

In April 2019, the LIGO and Virgo gravitational wave observatories announced the detection of candidate event that is, with a probability 99.94%, the merger of two neutron stars. Despite extensive follow-up observations, no electromagnetic counterpart could be identified. [23] [24] [25]

In 2023, an observation of the kilonova GRB 230307A was published, including likely observations of the spectra of tellurium and lanthanide elements. [26]

XT2 (magnetar)

In 2019, analysis of data from the Chandra X-ray Observatory revealed another binary neutron star merger at a distance of 6.6 billion light years, an x-ray signal called XT2. The merger produced a magnetar; its emissions could be detected for several hours. [27]

External Impact

Effect on Earth

The emission from binary neutron star mergers can result in an extinction-level event if one were to occur within 10s of parsecs of Earth [28] . If the short Gamma Ray Burst (sGRB) struck Earth, the range of lethal influence extends to hundreds of parsec [29] . When considering other emission components, like near-earth supernovae, the high energy photon emission in the form of gamma rays and x-rays depletes the ozone leaving Earth’s inhabitants susceptible to harmful UVB radiation from the Sun.  However, neutron star mergers are unique in that they have multiple sources of harmful radiation, including emission from the radioactive decay of heavy elements [30] , scattered by the sGRB cocoon [31] , and the sGRB afterglow [32] as well as cosmic rays accelerated by the blast.  In order of arrival, the photons are first after the merger, and the cosmic rays arrive 100 to 1000s of years later. The ejected material sweeps up the interstellar medium and creates supernovae-remnant-like bubble with a lethal dose of cosmic rays held within it.  If the Earth were to be encapsulated by the remnant, the cosmic rays, like the gamma rays, would deplete the ozone and could interact with the atmosphere and yield weakly-interacting muons. These particles will be generated in a large enough quantity such that escape from them will not be possible, even in caves or underwater. The danger lies in their ability to cause birth defects and mutations when interacting with the DNA of organic beings [33] [34] .

Relative to supernovae, they influence a similar volume of space. They are also much rarer and have a stronger dependence on the orientation of the event with respect to Earth [28] . Thus, the overall the threat of binary neutron star mergers is quite small.

See also

Related Research Articles

<span class="mw-page-title-main">Neutron star</span> Collapsed core of a massive star

A neutron star is a collapsed core of a massive supergiant star. The stars that later collapse into neutron stars have a total mass of between 10 and 25 solar masses (M☉), possibly more if the star was especially rich in elements heavier than hydrogen and helium. Except for black holes, neutron stars are the smallest and densest known class of stellar objects. Neutron stars have a radius on the order of 10 kilometers (6 mi) and a mass of about 1.4 M☉. They result from the supernova explosion of a massive star, combined with gravitational collapse, that compresses the core past white dwarf star density to that of atomic nuclei.

<span class="mw-page-title-main">Gamma-ray burst</span> Flashes of gamma rays from distant galaxies

In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies, described by NASA as "the most powerful class of explosions in the universe". They are the most energetic and luminous electromagnetic events since the Big Bang. Bursts can last from ten milliseconds to several hours. After an initial flash of gamma rays, a longer-lived "afterglow" is usually emitted at longer wavelengths.

Timeline of neutron stars, pulsars, supernovae, and white dwarfs

<span class="mw-page-title-main">Fermi Gamma-ray Space Telescope</span> Space telescope for gamma-ray astronomy launched in 2008

The Fermi Gamma-ray Space Telescope, formerly called the Gamma-ray Large Area Space Telescope (GLAST), is a space observatory being used to perform gamma-ray astronomy observations from low Earth orbit. Its main instrument is the Large Area Telescope (LAT), with which astronomers mostly intend to perform an all-sky survey studying astrophysical and cosmological phenomena such as active galactic nuclei, pulsars, other high-energy sources and dark matter. Another instrument aboard Fermi, the Gamma-ray Burst Monitor, is being used to study gamma-ray bursts and solar flares.

<span class="mw-page-title-main">Virgo interferometer</span> Gravitational wave detector in Santo Stefano a Macerata, Tuscany, Italy

The Virgo interferometer is a large Michelson interferometer designed to detect the gravitational waves predicted by general relativity. It is located in Santo Stefano a Macerata, near the city of Pisa, Italy. The instrument's two arms are three kilometres long, housing its mirrors and instrumentation inside an ultra-high vacuum.

<span class="mw-page-title-main">Gravitational-wave astronomy</span> Branch of astronomy using gravitational waves

Gravitational-wave astronomy is a subfield of astronomy concerned with the detection and study of gravitational waves emitted by astrophysical sources.

<span class="mw-page-title-main">Gamma-ray burst progenitors</span> Types of celestial objects that can emit gamma-ray bursts

Gamma-ray burst progenitors are the types of celestial objects that can emit gamma-ray bursts (GRBs). GRBs show an extraordinary degree of diversity. They can last anywhere from a fraction of a second to many minutes. Bursts could have a single profile or oscillate wildly up and down in intensity, and their spectra are highly variable unlike other objects in space. The near complete lack of observational constraint led to a profusion of theories, including evaporating black holes, magnetic flares on white dwarfs, accretion of matter onto neutron stars, antimatter accretion, supernovae, hypernovae, and rapid extraction of rotational energy from supermassive black holes, among others.

Nial Rahil Tanvir is a British astronomer at the University of Leicester. His research specialisms are the Extragalactic distance scale, Galaxy evolution and Gamma ray bursts. Tanvir has featured in various TV programs, including The Sky at Night hosted by Sir Patrick Moore, and Horizon

<span class="mw-page-title-main">Kilonova</span> Neutron star merger

A kilonova is a transient astronomical event that occurs in a compact binary system when two neutron stars or a neutron star and a black hole merge. These mergers are thought to produce gamma-ray bursts and emit bright electromagnetic radiation, called "kilonovae", due to the radioactive decay of heavy r-process nuclei that are produced and ejected fairly isotropically during the merger process. The measured high sphericity of the kilonova AT2017gfo at early epochs was deduced from the blackbody nature of its spectrum.

Multi-messenger astronomy is astronomy based on the coordinated observation and interpretation of signals carried by disparate "messengers": electromagnetic radiation, gravitational waves, neutrinos, and cosmic rays. They are created by different astrophysical processes, and thus reveal different information about their sources.

<span class="mw-page-title-main">First observation of gravitational waves</span> 2015 direct detection of gravitational waves by the LIGO and VIRGO interferometers

The first direct observation of gravitational waves was made on 14 September 2015 and was announced by the LIGO and Virgo collaborations on 11 February 2016. Previously, gravitational waves had been inferred only indirectly, via their effect on the timing of pulsars in binary star systems. The waveform, detected by both LIGO observatories, matched the predictions of general relativity for a gravitational wave emanating from the inward spiral and merger of a pair of black holes of around 36 and 29 solar masses and the subsequent "ringdown" of the single resulting black hole. The signal was named GW150914. It was also the first observation of a binary black hole merger, demonstrating both the existence of binary stellar-mass black hole systems and the fact that such mergers could occur within the current age of the universe.

<span class="mw-page-title-main">Hypernova</span> Supernova that ejects a large mass at unusually high velocity

A hypernova is a very energetic supernova which is believed to result from an extreme core-collapse scenario. In this case, a massive star collapses to form a rotating black hole emitting twin astrophysical jets and surrounded by an accretion disk. It is a type of stellar explosion that ejects material with an unusually high kinetic energy, an order of magnitude higher than most supernovae, with a luminosity at least 10 times greater. Hypernovae release so much of gamma rays they usually appear similar to a type Ic supernova, but with unusually broad spectral lines indicating an extremely high expansion velocity. Hypernovae are one of the mechanisms for producing long gamma ray bursts (GRBs), which range from 2 seconds to over a minute in duration. They have also been referred to as superluminous supernovae, though that classification also includes other types of extremely luminous stellar explosions that have different origins.

<span class="mw-page-title-main">GW170817</span> Gravitational-wave signal detected in 2017

GW 170817 was a gravitational wave (GW) signal observed by the LIGO and Virgo detectors on 17 August 2017, originating from the shell elliptical galaxy NGC 4993. The signal was produced by the last moments of the inspiral process of a binary pair of neutron stars, ending with their merger. It is the first GW observation that has been confirmed by non-gravitational means. Unlike the five previous GW detections—which were of merging black holes and thus not expected to produce a detectable electromagnetic signal—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. The discovery and subsequent observations of GW 170817 were given the Breakthrough of the Year award for 2017 by the journal Science.

<span class="mw-page-title-main">NGC 4993</span> Galaxy in the constellation of Hydra

NGC 4993 is a lenticular galaxy located about 140 million light-years away in the constellation Hydra. It was discovered on 26 March 1789 by William Herschel and is a member of the NGC 4993 Group.

<span class="mw-page-title-main">GW170608</span>

GW170608 was a gravitational wave event that was recorded on 8 June 2017 at 02:01:16.49 UTC by Advanced LIGO. It originated from the merger of two black holes with masses of and . The resulting black hole had a mass around 18 solar masses. About one solar mass was converted to energy in the form of gravitational waves.

PyCBC is an open source software package primarily written in the Python programming language which is designed for use in gravitational-wave astronomy and gravitational-wave data analysis. PyCBC contains modules for signal processing, FFT, matched filtering, gravitational waveform generation, among other tasks common in gravitational-wave data analysis.

Daryl Haggard is an American-Canadian astronomer and associate professor of physics in the Department of Physics at McGill University and the McGill Space Institute.

<span class="mw-page-title-main">GRB 150101B</span>

GRB 150101B is a gamma-ray burst (GRB) that was detected on 1 January 2015 at 15:23 UT by the Burst Alert Telescope (BAT) on board the Swift Observatory Satellite, and at 15:23:35 UT by the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope. The GRB was determined to be 1.7 billion light-years (0.52 Gpc) from Earth near the host galaxy 2MASX J12320498-1056010 in the constellation Virgo. The characteristics of GRB 150101B are remarkably similar to the historic event GW170817, a merger of neutron stars.

References

  1. ↑ Rosswog, Stephan (2013). "Astrophysics: Radioactive glow as a smoking gun". Nature. 500 (7464): 535–6. Bibcode:2013Natur.500..535R. doi: 10.1038/500535a . PMID   23985867. S2CID   4401544.
  2. ↑ Stromberg, Joseph (16 July 2013). "All the Gold in the Universe Could Come from the Collisions of Neutron Stars". Smithsonian . Retrieved 27 April 2014.
  3. ↑ "James Webb Space Telescope finds neutron star mergers forge gold in the cosmos: 'It was thrilling'". Space.com . 21 February 2024.
  4. ↑ Tanvir, N. R.; Levan, A. J.; Fruchter, A. S.; Hjorth, J.; Hounsell, R. A.; Wiersema, K.; Tunnicliffe, R. L. (2013). "A "kilonova" associated with the short-duration γ-ray burst GRB 130603B". Nature. 500 (7464): 547–9. arXiv: 1306.4971 . Bibcode:2013Natur.500..547T. doi:10.1038/nature12505. PMID   23912055. S2CID   205235329.
  5. ↑ Abbott, B. P.; et al. (LIGO Scientific Collaboration & Virgo Collaboration) (16 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. S2CID   217163611.
  6. ↑ Scharping, Nathaniel (18 October 2017). "Gravitational Waves Show How Fast The Universe is Expanding". Astronomy . Retrieved 18 October 2017.
  7. ↑ Cho, Adrian (16 October 2017). "Merging neutron stars generate gravitational waves and a celestial light show". Science . Retrieved 16 October 2017.
  8. ↑ Landau, Elizabeth; Chou, Felicia; Washington, Dewayne; Porter, Molly (16 October 2017). "NASA Missions Catch First Light from a Gravitational-Wave Event". NASA . Retrieved 16 October 2017.
  9. ↑ Overbye, Dennis (16 October 2017). "LIGO Detects Fierce Collision of Neutron Stars for the First Time". The New York Times . Retrieved 16 October 2017.
  10. ↑ Krieger, Lisa M. (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.
  11. ↑ Abbott, B. P.; 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.
  12. ↑ Pan, Y.-C.; et al. (2017). "The Old Host-galaxy Environment of SSS17a, the First Electromagnetic Counterpart to a Gravitational-wave Source". The Astrophysical Journal. 848 (2): L30. arXiv: 1710.05439 . Bibcode:2017ApJ...848L..30P. doi: 10.3847/2041-8213/aa9116 . S2CID   3516168.
  13. ↑ Nature Astronomy (16 Oct 2017) Kilonovae, short gamma-ray bursts & neutron star mergers
  14. ↑ Pease, Roland (2 May 2019). "Gravitational waves hunt now in overdrive". BBC News.
  15. ↑ Eric C. Bellm, Shrinivas R. Kulkarni, Matthew J. Graham, Richard Dekany, Roger M. Smith, Reed Riddle, Frank J. Masci, George Helou, Thomas A. Prince, Scott M. Adams (2018 December 7) The Zwicky Transient Facility: System Overview, Performance, and First Results
  16. ↑ "All in the family: Kin of gravitational wave source discovered". EurekAlert! (Press release). University of Maryland. 16 October 2018. Retrieved 17 October 2018.
  17. ↑ Troja, E.; et al. (16 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.
  18. ↑ Mohon, Lee (16 October 2018). "GRB 150101B: A Distant Cousin to GW170817". NASA . Retrieved 17 October 2018.
  19. ↑ Wall, Mike (17 October 2018). "Powerful Cosmic Flash Is Likely Another Neutron-Star Merger". Space.com . Retrieved 17 October 2018.
  20. ↑ Lerner, Louise (22 October 2018). "Gravitational waves could soon provide measure of universe's expansion". Phys.org . Retrieved 22 October 2018.
  21. ↑ Chen, Hsin-Yu; Fishbach, Maya; Holz, Daniel E. (17 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.
  22. ↑ Charlie Wood (13 Dec 2021) Cosmologists Parry Attacks on the Vaunted Cosmological Principle
  23. ↑ "Breaking: LIGO Detects Gravitational Waves From Another Neutron Star Merger". D-brief. 25 April 2019. Retrieved 13 August 2019.
  24. ↑ "GraceDB |". gracedb.ligo.org. Retrieved 13 August 2019.
  25. ↑ Hosseinzadeh, G.; Cowperthwaite, P. S.; Gomez, S.; Villar, V. A. (18 July 2019). "Follow-up of the Neutron Star Bearing Gravitational Wave Candidate Events S190425z and S190426c with MMT and SOAR". Astrophys. J. 880 (1): L4. arXiv: 1905.02186 . Bibcode:2019ApJ...880L...4H. doi: 10.3847/2041-8213/ab271c . hdl:10150/633863. S2CID   146121014.
  26. ↑ Levan, Andrew; Gompertz, Benjamin P.; Salafia, Om Sharan; Bulla, Mattia; Burns, Eric; Hotokezaka, Kenta; Izzo, Luca; Lamb, Gavin P.; Malesani, Daniele B.; Oates, Samantha R.; Ravasio, Maria Edvige; Rouco Escorial, Alicia; Schneider, Benjamin; Sarin, Nikhil; Schulze, Steve (25 October 2023). "Heavy element production in a compact object merger observed by JWST". Nature. 626 (8000): 737–741. arXiv: 2307.02098 . doi:10.1038/s41586-023-06759-1. ISSN   0028-0836. PMC   10881391 . PMID   37879361.
  27. ↑ Klesman, Alison (18 April 2019). "A new neutron star merger is caught on X-ray camera". Astronomy. Retrieved 18 April 2019.
  28. 1 2 Perkins, Haille M. L.; Ellis, John; Fields, Brian D.; Hartmann, Dieter H.; Liu, Zhenghai; McLaughlin, Gail C.; Surman, Rebecca; Wang, Xilu (1 February 2024). "Could a Kilonova Kill: A Threat Assessment". The Astrophysical Journal. 961 (2): 170. arXiv: 2310.11627 . Bibcode:2024ApJ...961..170P. doi: 10.3847/1538-4357/ad12b7 . ISSN   0004-637X.
  29. ↑ Melott, Adrian L.; Thomas, Brian C. (May 2011). "Astrophysical Ionizing Radiation and Earth: A Brief Review and Census of Intermittent Intense Sources". Astrobiology. 11 (4): 343–361. arXiv: 1102.2830 . Bibcode:2011AsBio..11..343M. doi:10.1089/ast.2010.0603. ISSN   1531-1074. PMID   21545268.
  30. ↑ Wang 王夕露), Xilu; N3AS Collaboration; Vassh, Nicole; FIRE Collaboration; Sprouse, Trevor; Mumpower, Matthew; Vogt, Ramona; Randrup, Jorgen; Surman, Rebecca (1 November 2020). "MeV Gamma Rays from Fission: A Distinct Signature of Actinide Production in Neutron Star Mergers". The Astrophysical Journal Letters. 903 (1): L3. arXiv: 2008.03335 . Bibcode:2020ApJ...903L...3W. doi: 10.3847/2041-8213/abbe18 . ISSN   2041-8205.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  31. ↑ Kisaka, Shota; Ioka, Kunihito; Kashiyama, Kazumi; Nakamura, Takashi (1 November 2018). "Scattered Short Gamma-Ray Bursts as Electromagnetic Counterparts to Gravitational Waves and Implications of GW170817 and GRB 170817A". The Astrophysical Journal. 867 (1): 39. arXiv: 1711.00243 . Bibcode:2018ApJ...867...39K. doi: 10.3847/1538-4357/aae30a . ISSN   0004-637X.
  32. ↑ Makhathini, S.; Mooley, K. P.; Brightman, M.; Hotokezaka, K.; Nayana, A. J.; Intema, H. T.; Dobie, D.; Lenc, E.; Perley, D. A.; Fremling, C.; Moldòn, J.; Lazzati, D.; Kaplan, D. L.; Balasubramanian, A.; Brown, I. S. (1 December 2021). "The Panchromatic Afterglow of GW170817: The Full Uniform Data Set, Modeling, Comparison with Previous Results, and Implications". The Astrophysical Journal. 922 (2): 154. arXiv: 2006.02382 . Bibcode:2021ApJ...922..154M. doi: 10.3847/1538-4357/ac1ffc . ISSN   0004-637X.
  33. ↑ Dar, Arnon; Laor, Ari; Shaviv, Nir J. (29 June 1998). "Life Extinctions by Cosmic Ray Jets". Physical Review Letters. 80 (26): 5813–5816. arXiv: astro-ph/9705008 . Bibcode:1998PhRvL..80.5813D. doi:10.1103/PhysRevLett.80.5813. ISSN   0031-9007.
  34. ↑ Juckett, David A. (November 2009). "A 17-year oscillation in cancer mortality birth cohorts on three continents – synchrony to cosmic ray modulations one generation earlier". International Journal of Biometeorology. 53 (6): 487–499. Bibcode:2009IJBm...53..487J. doi:10.1007/s00484-009-0237-0. ISSN   0020-7128. PMID   19506913.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.