Great Annihilator

1E1740.7-2942, or the Great Annihilator,[3][4] is a Milky Way microquasar, located near the Galactic Center on the sky.[5][2] It likely consists of a black hole and a companion star. It is one of the brightest X-ray sources in the region around the Galactic Center.[6]

Great Annihilator
Ss433 art big.gif
Artist's impression of the microquasar like the Great Annihilator
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
Right ascension 17h 43m 54.83s[1]
Declination −29° 44′ 42.6″[1]
Distance16,000 ly
(5,000[2] pc)
Database references

The object was first detected in soft X-rays by the Einstein Observatory,[when?] and later detected in hard X-rays by the Soviet Granat space observatory.[2] Followup observations by the SIGMA detector on board Granat showed that the object was a variable emitter of massive amounts of photon pairs at 511 keV, which usually indicates the annihilation of an electron-positron pair.[7][8] This led to the nickname, "Great Annihilator."[9] Early observations also showed a spectrum similar to that of the Cygnus X-l, a black hole with a stellar companion, which suggested that Great Annihilator was also a stellar mass black hole.[7]

The object also has a radio source counterpart that emits jets approximately 1.5 pc (5 ly) long.[10] These jets are probably synchrotron emission from positron-electron pairs streaming out at high velocities from the source of antimatter. Modeling of the observed precession of these jets gives an object distance of approximately 5 kpc (or 16,000 ly).[2] This means that while the object is likely located along our line of sight towards the center of the Milky Way, it may be closer to us than Sagittarius A*, the black hole at the center of our galaxy.


  1. ^ a b "NAME Great Annihilator". SIMBAD. Centre de données astronomiques de Strasbourg.
  2. ^ a b c d Luque-Escamilla, Pedro L.; Martí, Josep; Martínez-Aroza, José (2015-12-01). "The precessing jets of 1E 1740.7−2942". Astronomy & Astrophysics. 584: A122. doi:10.1051/0004-6361/201527238. ISSN 0004-6361.
  3. ^ Sunyaev, R. A.; Borozdin, K. N.; Aleksandrovich, N. L.; Arefev, V. A.; Kaniovskii, A. S.; Efremov, V. V.; Maisack, M.; Reppin, C.; Skinner, J. K. (November 1994). "Observations of X-ray novae in Vela (1993), Ophiuchus (1993), and Perseus (1992) using the instruments of the Mir-Kvant module". Astronomy Letters. 20 (6): 777. Bibcode:1994AstL...20..777S.
  4. ^ Odenwald, Sten (1997). "What do we know about the 'Great Annihilator' in the center of the Milky Way?". Astronomy Cafe. Archived from the original on 16 January 2013. Retrieved 4 August 2014.
  5. ^ Mirabel, I. F. "The Great Annihilator in the Central Region of the Galaxy" (PDF). pp. 51–54.
  6. ^ Stecchini, Paulo Eduardo; Castro, Manuel; Jablonski, Francisco; D’Amico, Flavio; Braga, João (2017-06-30). "Tandem Swift and INTEGRAL Data to Revisit the Orbital and Superorbital Periods of 1E 1740.7–2942". The Astrophysical Journal. 843 (1): L10. arXiv:1707.00730. Bibcode:2017ApJ...843L..10S. doi:10.3847/2041-8213/aa7942. ISSN 2041-8213. S2CID 119354178.
  7. ^ a b Sunyaev, R.; Churazov, E.; Gilfanov, M.; Pavlinsky, M.; Grebenev, S.; Babalyan, G.; Dekhanov, I.; Khavenson, N.; Bouchet, L.; Mandrou, P.; Roques, J. P. (December 1991). "Three spectral states of 1E 1740.7 - 2942 - From standard Cygnus X-1 type spectrum to the evidence of electron-positron annihilation feature". The Astrophysical Journal. 383: L49. Bibcode:1991ApJ...383L..49S. doi:10.1086/186238. ISSN 0004-637X.
  8. ^ Bouchet, L.; Mandrou, P.; Roques, J. P.; Vedrenne, G.; Cordier, B.; Goldwurm, A.; Lebrun, F.; Paul, J.; Sunyaev, R.; Churazov, E.; Gilfanov, M. (December 1991). "Sigma discovery of variable e(+)-e(-) annihilation radiation from the near Galactic center variable compact source 1E 1740.7 - 2942". The Astrophysical Journal. 383: L45. doi:10.1086/186237. ISSN 0004-637X.
  9. ^ "Milky Way Monster". Time. 1992-07-27. ISSN 0040-781X. Retrieved 2019-10-24.
  10. ^ Mirabel, I. F.; Rodríguez, L. F.; Cordier, B.; Paul, J.; Lebrun, F. (July 1992). "A double-sided radio jet from the compact Galactic Centre annihilator 1E1740.7–2942". Nature. 358 (6383): 215–217. Bibcode:1992Natur.358..215M. doi:10.1038/358215a0. ISSN 0028-0836. S2CID 4264588.