          APOD: 2017 October 31 - Dark Matter in a Simulated Universe

                         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 31
                                      [2]
                     Dark Matter in a Simulated Universe
 Illustration Credit & Copyright Tom Abel [3]  & Ralf Kaehler [4] (KIPAC [5] ,
                             SLAC [6] ), AMNH [7]

Explanation: Is our universe haunted? It might look that way on this dark
matter [8]  map. The gravity of unseen dark matter [9] is the leading
explanation for why galaxies rotate so fast [10] , why galaxies orbit clusters
so fast [11] , why gravitational lenses so strongly deflect light [12] , and
why visible matter [13]  is distributed as it is both in the local universe
[14]  and on the cosmic [15] microwave background [16] . The featured image
from the American Museum of Natural History [17] 's Hayden Planetarium [18]
Space Show Dark Universe [19] highlights one example of how pervasive dark
matter might haunt our universe. In this frame from a detailed computer
simulation [20] , complex filaments of dark matter, shown in black, are strewn
about the universe [21]  like spider webs [22] , while the relatively rare
clumps of familiar baryon [23] ic matter are colored orange. These simulations
[24]  are good statistical matches to astronomical observations. In what is
perhaps a scarier turn of events, dark matter [25]  -- although quite strange
and in an unknown form [26]  -- is no longer thought to be the strangest
source of gravity in the universe [27] . That honor now falls to dark energy
[28] , a more uniform source of repulsive gravity [29] that seems to now
dominate the expansion of the entire universe.

              Not only Halloween: Today is Dark Matter Day [30] .
                    Tomorrow's picture: thor's helmet [31]

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Site notes:
  [1] archivepix.html
  [2] image/1710/DarkMatter_KipacAmnh_1200.jpg
  [3] https://physics.stanford.edu/people/faculty/tom-abel
  [4] https://www.slac.stanford.edu/~kaehler/
  [5] http://kipac-web.stanford.edu/
  [6] https://www6.slac.stanford.edu/
  [7] https://www.amnh.org/
  [8]
https://www.nasa.gov/audience/forstudents/9-12/features/
what-is-dark-matter.html
  [9] http://chandra.harvard.edu/xray_astro/dark_matter/
  [10] http://ircamera.as.arizona.edu/NatSci102/NatSci/lectures/darkmatter.htm
  [11]
https://medium.com/starts-with-a-bang/
galaxy-clusters-prove-dark-matters-existence-fd962c979458
  [12] https://www.lsst.org/sites/default/files/img/xxnyt.jpg
  [13] ap140512.html
  [14] http://w.astro.berkeley.edu/~mwhite/models.html
  [15] http://background.uchicago.edu/~whu/intermediate/driving2.html
  [16] ap130325.html
  [17] https://www.amnh.org/
  [18] https://www.amnh.org/our-research/hayden-planetarium
  [19] https://www.amnh.org/exhibitions/space-show/dark-universe/
  [20] https://www.youtube.com/watch?v=zEEg1XkbXDo
  [21] ap111003.html
  [22] https://www.badspiderbites.com/giant-spider-web/
  [23] https://en.wikipedia.org/wiki/Baryon
  [24]
https://www.slac.stanford.edu/~kaehler/homepage/visualizations/dark-matter.html
  [25] https://en.wikipedia.org/wiki/Dark_matter
  [26] https://home.cern/about/physics/dark-matter
  [27] http://adsabs.harvard.edu/abs/2008AmJPh..76..265N
  [28] https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy
  [29]
http://www.preposterousuniverse.com/blog/2013/11/16/
why-does-dark-energy-make-the-universe-accelerate/
  [30] https://www.darkmatterday.com/
  [31] ap171101.html
  [32] ap171030.html
  [33] archivepix.html
  [34] lib/apsubmit2015.html
  [35] lib/aptree.html
  [36] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [37] calendar/allyears.html
  [38] /apod.rss
  [39] lib/edlinks.html
  [40] lib/about_apod.html
  [41] http://asterisk.apod.com/discuss_apod.php?date=171031
  [42] ap171101.html
  [43] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [44] http://www.phy.mtu.edu/
  [45] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [46] http://www.astro.umd.edu/
  [47] lib/about_apod.html#srapply
  [48] https://www.nasa.gov/about/highlights/HP_Privacy.html
  [49] https://astrophysics.gsfc.nasa.gov/
  [50] https://www.nasa.gov/
  [51] https://www.nasa.gov/centers/goddard/
  [52] http://www.mtu.edu/
