Astronomy:NGC 4993

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Short description: Galaxy in the constellation of Hydra
NGC 4993
NGC 4993 and GRB170817A after glow.gif
NGC 4993 and GRB 170817A afterglow as taken by Hubble Space Telescope[1]
Observation data (J2000 epoch)
ConstellationHydra
Right ascension 13h 09m 47.7s[2]
Declination−23° 23′ 02″[2]
Redshift0.009727[2]
Helio radial velocity2916 km/s[2]
Distance44.1 Mpc (144 Mly)[2]
Group or clusterNGC 4993 Group[3]
Apparent magnitude (V)13.32[2]
Characteristics
Type(R')SAB0^-(rs)[2]
Size~55,000 ly (17 kpc) (estimated)[2]
Apparent size (V)1.3 x 1.1[2]
Notable featuresHost of neutron star merger detected as gravitational wave GW170817 and gamma-ray burst GRB 170817A
Other designations
NGC 4994, ESO 508-18, AM 1307-230, MCG -4-31-39, PGC 45657, WH III 766[4]

Coordinates: Sky map 13h 09m 47.2s, −23° 23′ 4″

NGC 4993 starmap near ψ Hydrae, near galaxies of NGC 4968, NGC 4970, NGC 5042, IC 4180, IC 4197

NGC 4993 (also catalogued as NGC 4994 in the New General Catalogue) is a lenticular galaxy[5] located about 140 million light-years away[2] in the constellation Hydra.[6] It was discovered on 26 March 1789[7] by William Herschel[6][7] and is a member of the NGC 4993 Group.[3]

NGC 4993 is the site of GW170817, the first astronomical event detected in both electromagnetic and gravitational radiation, the collision of two neutron stars, a discovery given the Breakthrough of the Year award for 2017 by the journal Science.[8][9] Detecting a gravitational wave event associated with the gamma-ray burst provided direct confirmation that binary neutron star collisions produce short gamma-ray bursts.[10]

Physical characteristics

NGC 4993 has several concentric shells of stars and large dust lane with diameter of approximately a few kiloparsecs which surrounds the nucleus and is stretched out into an "s" shape. The dust lane appears to be connected to a small dust ring with a diameter of ~330 ly (0.1 kpc).[11] These features in NGC 4993 may be the result[12] of a recent merger with a gaseous late-type galaxy that occurred about 400 million years ago.[13] However, Palmese et al. suggested that the galaxy involved in the merger was a gas-poor galaxy.[14]

Dark matter content

NGC 4993 has a dark matter halo with an estimated mass of 193.9×1010 M☉.[13]

Globular clusters

NGC 4993 has an estimated population of 250 globular clusters.[5]

The luminosity of NGC 4993 indicates that the globular cluster system surrounding the galaxy may be dominated by metal-poor globular clusters.[15]

Supermassive black hole

NGC 4993 has a supermassive black hole with an estimated mass of roughly 80 to 100 million solar masses (8×107 M☉).[16]

Galactic nucleus activity

The presence of weak O III, NII and SII emission lines in the nucleus of NGC 4993 and the relatively high ratio of [NII]λ6583/Hα suggest that NGC 4993 is a low-luminosity AGN (LLAGN).[16] The activity may have been triggered by gas from the late-type galaxy as it merged with NGC 4993.[13]

Neutron star merger observations

Main page: Astronomy:GW170817

In August 2017, rumors circulated[17] regarding a short gamma-ray burst designated GRB 170817A, of the type conjectured to be emitted in the collision of two neutron stars.[18] On 16 October 2017, the LIGO and Virgo collaborations announced that they had detected a gravitational wave event, designated GW170817. The gravitational wave signal matched prediction for the merger of two neutron stars, two seconds before the gamma-ray burst. The gravitational wave signal, which had a duration of about 100 seconds, was the first gravitational wave detection of the merger of two neutron stars.[1][19][20][21][22]

An optical transient, AT 2017gfo (also known as SSS 17a), was detected in NGC 4993 11 hours after the gravitational wave and gamma-ray signals, allowing the location of the merger to be determined. The optical emission is thought to be due to a kilonova. The discovery of AT 2017gfo was the first observation (and first localisation) of an electromagnetic counterpart to a gravitational wave source.[19][21][22][23][24]

GRB 170817A was a gamma-ray burst (GRB) detected by NASA's Fermi and ESA's INTEGRAL on 17 August 2017.[17][25][26][27] Although only localized to a large area of the sky, it is believed to correspond to the other two observations,[23] in part due to its arrival time 1.7 seconds after the GW event.

See also

References

  1. ↑ 1.0 1.1 Chou, Felicia; Washington, Dewayne; Porter, Molly (16 October 2017). "Release 17-083 - NASA Missions Catch First Light from a Gravitational-Wave Event". NASA. https://www.nasa.gov/press-release/nasa-missions-catch-first-light-from-a-gravitational-wave-event. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 "NASA/IPAC Extragalactic Database". Results for NGC 4993. http://nedwww.ipac.caltech.edu/. 
  3. ↑ 3.0 3.1 Hjorth, Jens; Levan, Andrew J.; Tanvir, Nial R.; Lyman, Joe D.; Wojtak, Radosław; Schrøder, Sophie L.; Mandel, Ilya; Gall, Christa et al. (2017-10-16). "The Distance to NGC 4993: The Host Galaxy of the Gravitational-wave Event GW170817" (in en). The Astrophysical Journal 848 (2): L31. doi:10.3847/2041-8213/aa9110. Bibcode: 2017ApJ...848L..31H. 
  4. ↑ Staff (2017). "Galaxy NGC 4993 - Galaxy in Hydra Constellation". dso-browser.com. https://dso-browser.com/deep-sky/6088/ngc-4993/galaxy. 
  5. ↑ 5.0 5.1 Abbott, B. P.; Abbott, R.; Abbott, T. D.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P. et al. (2017-12-01). "On the Progenitor of Binary Neutron Star Merger GW170817" (in en). The Astrophysical Journal 850 (2): L40. doi:10.3847/2041-8213/aa93fc. Bibcode: 2017ApJ...850L..40A. 
  6. ↑ 6.0 6.1 "NGC 4993". http://www.docdb.net/show_object.php?id=ngc_4993. 
  7. ↑ 7.0 7.1 "New General Catalog Objects: NGC 4950 - 4999" (in en-US). https://cseligman.com/text/atlas/ngc49a.htm#4993. 
  8. ↑ "Breakthrough of the year 2017" (in en). 22 December 2017. https://vis.sciencemag.org/breakthrough2017/. 
  9. ↑ Cho, Adrian (2017). "Cosmic convergence". Science 358 (6370): 1520–1521. doi:10.1126/science.358.6370.1520. PMID 29269456. Bibcode: 2017Sci...358.1520C. 
  10. ↑ Overbye, Dennis (16 October 2017). "LIGO Detects Fierce Collision of Neutron Stars for the First Time" (in en-US). The New York Times. https://www.nytimes.com/2017/10/16/science/ligo-neutron-stars-collision.html. 
  11. ↑ Blanchard, P. K.; Berger, E.; Fong, W.; Nicholl, M.; Leja, J.; Conroy, C.; Alexander, K. D.; Margutti, R. et al. (2017-10-16). "The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VII. Properties of the Host Galaxy and Constraints on the Merger Timescale". The Astrophysical Journal 848 (2): L22. doi:10.3847/2041-8213/aa9055. Bibcode: 2017ApJ...848L..22B. 
  12. ↑ Im, Myungshin; Yoon, Yongmin; Lee, Seong-Kook J.; Lee, Hyung Mok; Kim, Joonho; Lee, Chung-Uk; Kim, Seung-Lee; Troja, Eleonora et al. (2017-10-26). "Distance and Properties of NGC 4993 as the Host Galaxy of the Gravitational-wave Source GW170817" (in en). The Astrophysical Journal 849 (1): L16. doi:10.3847/2041-8213/aa9367. Bibcode: 2017ApJ...849L..16I. 
  13. ↑ 13.0 13.1 13.2 Ebrová, Ivana; Bílek, Michal (2020). "NGC 4993 the shell galaxy host of GW170817: constraints on the recent galactic merger". Astronomy & Astrophysics 634: A73. doi:10.1051/0004-6361/201935219. Bibcode: 2020A&A...634A..73E. 
  14. ↑ Palmese, A.; Hartley, W.; Tarsitano, F.; Conselice, C.; Lahav, O.; Allam, S.; Annis, J.; Lin, H. et al. (2017-11-09). "Evidence for Dynamically Driven Formation of the GW170817 Neutron Star Binary in NGC 4993" (in en). The Astrophysical Journal 849 (2): L34. doi:10.3847/2041-8213/aa9660. Bibcode: 2017ApJ...849L..34P. 
  15. ↑ Lee, Myung Gyoon; Kang, Jisu; Im, Myungshin (20 May 2018). "A Globular Cluster Luminosity Function Distance to NGC 4993 Hosting a Binary Neutron Star Merger GW170817/GRB 170817A". The Astrophysical Journal Letters 859 (1): L6. doi:10.3847/2041-8213/aac2e9. Bibcode: 2018ApJ...859L...6L. 
  16. ↑ 16.0 16.1 Wu, Qingwen; Feng, Jianchao; Fan, Xuliang (6 March 2018). "The Possible Submillimeter Bump and Accretion-jet in the Central Supermassive Black Hole of NGC 4993". The Astrophysical Journal 855 (1): 46. doi:10.3847/1538-4357/aaac28. Bibcode: 2018ApJ...855...46W. 
  17. ↑ 17.0 17.1 Drake, Nadia (25 August 2017). "Strange stars caught wrinkling spacetime? Get the facts.". National Geographic. http://news.nationalgeographic.com/2017/08/new-gravitational-waves-neutron-stars-ligo-space-science/. 
  18. ↑ Nakar, E. (2007). "Short-hard gamma-ray bursts". Physics Reports 442 (1–6): 166–236. doi:10.1016/j.physrep.2007.02.005. Bibcode: 2007PhR...442..166N. 
  19. ↑ 19.0 19.1 Landau, Elizabeth; Chou, Felicia; Washington, Dewayne; Porter, Molly (16 October 2017). "NASA Missions Catch First Light from a Gravitational-Wave Event". NASA. https://www.jpl.nasa.gov/news/news.php?feature=6975. 
  20. ↑ Abbott, B.P. (16 October 2017). "GW 170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral". Physical Review Letters 119 (16): 161101. doi:10.1103/PhysRevLett.119.161101. PMID 29099225. Bibcode: 2017PhRvL.119p1101A. 
  21. ↑ 21.0 21.1 Cho, Adrian (16 October 2017). "Merging neutron stars generate gravitational waves and a celestial light show". Science. doi:10.1126/science.aar2149. https://www.science.org/content/article/merging-neutron-stars-generate-gravitational-waves-and-celestial-light-show. 
  22. ↑ 22.0 22.1 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. http://www.mercurynews.com/2017/10/16/a-bright-light-seen-across-the-universe-proving-einstein-right/. 
  23. ↑ 23.0 23.1 Overbye, Dennis (16 October 2017). "LIGO Detects Fierce Collision of Neutron Stars for the First Time". The New York Times. https://www.nytimes.com/2017/10/16/science/ligo-neutron-stars-collision.html. 
  24. ↑ Abbott, B. P. (16 October 2017). "GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral". Physical Review Letters 119 (16): 161101. doi:10.1103/PhysRevLett.119.161101. PMID 29099225. Bibcode: 2017PhRvL.119p1101A. 
  25. ↑ von Kienlin, Andreas (17 August 2017). "GCN Circular Number 21520; GRB 170817A: Fermi GBM detection; 2017-08-17 20:00:07 GMT". Max Planck Institute for Extraterrestrial Physics. https://gcn.gsfc.nasa.gov/gcn3/21520.gcn3. 
  26. ↑ Castelvecchi, Davide (25 August 2017). "Rumours swell over new kind of gravitational-wave sighting". Nature (Nature News). doi:10.1038/nature.2017.22482. https://www.nature.com/news/rumours-swell-over-new-kind-of-gravitational-wave-sighting-1.22482. 
  27. ↑ Sokol, Joshua (25 August 2017). "What Happens When Two Neutron Stars Collide?". Wired. https://www.wired.com/story/what-happens-when-two-neutron-stars-collide-scientific-revolution/. Retrieved 28 August 2017. 

External links



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