           APOD: 2017 October 22 - Two Black Holes Dancing in 3C 75

                         Astronomy Picture of the Day

    Discover the cosmos! [1] Each day a different image or photograph of our
 fascinating universe is featured, along with a brief explanation written by a
                           professional astronomer.

                                2017 October 22
                                      [2]
                      Two Black Holes Dancing in 3C 75
  Image Credit: X-Ray: NASA [3] / CXC [4] / D. Hudson, T. Reiprich et al. [5]
                  (AIfA [6] ); Radio: NRAO/VLA/ [7] NRL [8]

Explanation: What's happening at the center of active galaxy 3C 75? The two
bright sources at the center of this composite x-ray [9]  (blue)/ radio [10]
(pink) image are co-orbiting supermassive black holes powering the giant radio
source 3C 75 [11] . Surrounded by multimillion degree x-ray [12]  emitting
gas, and blasting out jets of relativistic particles the supermassive black
holes [13]  are separated by 25,000 light-years. At the cores of two merging
galaxies [14]  in the Abell [15]  400 galaxy cluster they are some 300 million
light-years away. Astronomers [16]  conclude that these two supermassive black
holes [17] are bound together by gravity in a binary system in part because
[18] the jets' consistent swept back appearance is most likely due to their
common motion as they speed through the hot cluster gas at 1200 kilometers per
second. Such spectacular cosmic merger [19] s are thought to be common in
crowded galaxy cluster [20]  environments in the distant universe. In their
final stages the mergers are expected to be intense sources of gravitational
waves [21] .

                  Free Download: The 2018 APOD Calendar [22]
                Tomorrow's picture: rosetta stone galaxy [23]

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    Authors & editors: Robert Nemiroff [35] (MTU [36] ) & Jerry Bonnell [37]
                                  (UMCP [38] )
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Site notes:
  [1] archivepix.html
  [2] image/1710/3c75_chandraNRAO_576.jpg
  [3] https://www.nasa.gov/
  [4] http://chandra.harvard.edu/
  [5] http://arxiv.org/abs/astro-ph/0603272
  [6] http://www.astro.uni-bonn.de/
  [7] http://www.vla.nrao.edu/
  [8] http://www.nrl.navy.mil/
  [9] http://chandra.harvard.edu/photo/2006/a400/
  [10] http://www.nrao.edu/imagegallery/image_contest/ image_contest.shtml
  [11] http://en.wikipedia.org/wiki/3C_75
  [12] https://science.nasa.gov/ems/11_xrays
  [13] http://astronomy.swin.edu.au/cosmos/S/Supermassive+Black+Hole
  [14] http://chandra.harvard.edu/photo/2006/a400/ animations.html
  [15] http://www.saguaroastro.org/content/ Abel-Galaxy-Clusters.htm
  [16] http://chandra.harvard.edu/press/06_releases/ press_040606.html
  [17] https://apod.nasa.gov/htmltest/rjn_bht.html
  [18] http://adsabs.harvard.edu/abs/2006A%26A...453..433H
  [19] ap071101.html
  [20] http://chandra.harvard.edu/xray_sources/galaxy_clusters.html
  [21] ap170602.html
  [22] https://apod.nasa.gov/apod/fap/APOD_Calendar_2018_300dpi.pdf
  [23] ap171023.html
  [24] ap171021.html
  [25] archivepix.html
  [26] lib/apsubmit2015.html
  [27] lib/aptree.html
  [28] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [29] calendar/allyears.html
  [30] /apod.rss
  [31] lib/edlinks.html
  [32] lib/about_apod.html
  [33] http://asterisk.apod.com/discuss_apod.php?date=171022
  [34] ap171023.html
  [35] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [36] http://www.phy.mtu.edu/
  [37] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [38] http://www.astro.umd.edu/
  [39] lib/about_apod.html#srapply
  [40] https://www.nasa.gov/about/highlights/HP_Privacy.html
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