Great Annihilator

{{short description|Microquasar}}

{{about|the astronomical object|the Swans album|The Great Annihilator}}

{{Starbox begin}}

{{Starbox observe

| epoch=J2000

| constell = Ophiuchus

| ra = {{RA|17|43|54.83}}{{cite simbad|title=NAME Great Annihilator}}

| dec = {{DEC|-29|44|42.6}}

}}

{{Starbox astrometry

| dist_ly=16,000

| dist_pc=5,000

}}

{{Starbox reference

| Simbad = NAME+Great+Annihilator

}}

{{Starbox end}}

1E1740.7-2942, or the Great Annihilator,{{cite journal

| last1=Sunyaev

| first1=R. A.

| author-link1=Rashid Sunyaev

| last2=Borozdin

| first2=K. N.

| last3=Aleksandrovich

| first3=N. L.

| last4=Arefev

| first4=V. A.

| last5=Kaniovskii

| first5=A. S.

| last6=Efremov

| first6=V. V.

| last7=Maisack

| first7=M.

| last8=Reppin

| first8=C.

| last9=Skinner

| first9=J. K.

| title=Observations of X-ray novae in Vela (1993), Ophiuchus (1993), and Perseus (1992) using the instruments of the Mir-Kvant module

| journal=Astronomy Letters

| date=November 1994

| volume=20

| issue=6

| page=777

| bibcode=1994AstL...20..777S

}}{{cite web

| last1=Odenwald

| first1=Sten

| author-link1=Sten Odenwald

| title=What do we know about the 'Great Annihilator' in the center of the Milky Way?

| url=http://www.astronomycafe.net/qadir/q1632.html

| website=Astronomy Cafe

| access-date=4 August 2014

| archive-url=https://web.archive.org/web/20130116203353/http://www.astronomycafe.net/qadir/q1632.html

| archive-date=16 January 2013

| date=1997}} is a Milky Way microquasar, located near the Galactic Center on the sky.{{cite web

| title=The Great Annihilator in the Central Region of the Galaxy

| last1=Mirabel

| first1=I. F.

| url=https://www.eso.org/sci/publications/messenger/archive/no.70-dec92/messenger-no70-51-54.pdf

| publisher=eso.org

| pages=51–54}}{{Cite journal|last1=Luque-Escamilla|first1=Pedro L.|last2=Martí|first2=Josep|last3=Martínez-Aroza|first3=José|date=2015-12-01|title=The precessing jets of 1E 1740.7−2942|journal=Astronomy & Astrophysics|language=en|volume=584|pages=A122|doi=10.1051/0004-6361/201527238|issn=0004-6361|doi-access=free|arxiv=1511.01425}} 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.{{Cite journal|last1=Stecchini|first1=Paulo Eduardo|last2=Castro|first2=Manuel|last3=Jablonski|first3=Francisco|last4=D’Amico|first4=Flavio|last5=Braga|first5=João|date=2017-06-30|title=Tandem Swift and INTEGRAL Data to Revisit the Orbital and Superorbital Periods of 1E 1740.7–2942|journal=The Astrophysical Journal|volume=843|issue=1|pages=L10|doi=10.3847/2041-8213/aa7942|issn=2041-8213|arxiv=1707.00730|bibcode=2017ApJ...843L..10S|s2cid=119354178 |doi-access=free }}

The object was first detected in soft X-rays by the Einstein Observatory,{{Cite journal |last1=Hertz |first1=P. |last2=Grindlay |first2=J. E. |date=1984-03-01 |title=The Einstein galactic plane survey : statistical analysis of the complete X-ray sample. |url=https://ui.adsabs.harvard.edu/abs/1984ApJ...278..137H |journal=The Astrophysical Journal |volume=278 |pages=137–149 |doi=10.1086/161775 |bibcode=1984ApJ...278..137H |issn=0004-637X}} and later detected in hard X-rays by the Soviet Granat space observatory. 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.{{Cite journal|last1=Sunyaev|first1=R.|last2=Churazov|first2=E.|last3=Gilfanov|first3=M.|last4=Pavlinsky|first4=M.|last5=Grebenev|first5=S.|last6=Babalyan|first6=G.|last7=Dekhanov|first7=I.|last8=Khavenson|first8=N.|last9=Bouchet|first9=L.|last10=Mandrou|first10=P.|last11=Roques|first11=J. P.|date=December 1991|title=Three spectral states of 1E 1740.7-2942 – From standard Cygnus X-1 type spectrum to the evidence of electron-positron annihilation feature|journal=The Astrophysical Journal|language=en|volume=383|pages=L49|doi=10.1086/186238|bibcode=1991ApJ...383L..49S|issn=0004-637X|doi-access=free}}{{Cite journal|last1=Bouchet|first1=L.|last2=Mandrou|first2=P.|last3=Roques|first3=J. P.|last4=Vedrenne|first4=G.|last5=Cordier|first5=B.|last6=Goldwurm|first6=A.|last7=Lebrun|first7=F.|last8=Paul|first8=J.|last9=Sunyaev|first9=R.|last10=Churazov|first10=E.|last11=Gilfanov|first11=M.|date=December 1991|title=Sigma discovery of variable e(+)–e(−) annihilation radiation from the near Galactic center variable compact source 1E 1740.7-2942|journal=The Astrophysical Journal|language=en|volume=383|pages=L45|doi=10.1086/186237|bibcode=1991ApJ...383L..45B |issn=0004-637X}} This led to the nickname, "Great Annihilator."{{Cite news|url=http://content.time.com/time/magazine/article/0,9171,976098,00.html|title=Milky Way Monster|date=1992-07-27|magazine=Time|access-date=2019-10-24|language=en-US|issn=0040-781X}} 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.

The object also has a radio source counterpart that emits jets approximately 1.5 pc (5 ly) long.{{Cite journal|last1=Mirabel|first1=I. F.|last2=Rodríguez|first2=L. F.|last3=Cordier|first3=B.|last4=Paul|first4=J.|last5=Lebrun|first5=F.|date=July 1992|title=A double-sided radio jet from the compact Galactic Centre annihilator 1E1740.7–2942|journal=Nature|language=en|volume=358|issue=6383|pages=215–217|doi=10.1038/358215a0|bibcode=1992Natur.358..215M|s2cid=4264588|issn=0028-0836}} 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). 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.