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| There may be no exotic dark matter, just gas that is very difficult to detect without large, sensitive instruments in space. Planck can only image some of this "dim" matter by overlaying hundreds of images, which cannot detect other baryons (mostly protons) that are not clustered this way. |
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| . [[ https://arxiv.org/abs/1709.05024 | A Search for Warm/Hot Gas Filaments Between Pairs of SDSS Luminous Red Galaxies ]] | . [[ https://arxiv.org/abs/1709.05024 | A Search for Warm/Hot Gas Filaments Between Pairs of SDSS Luminous Red Galaxies ]] |
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There may be no exotic dark matter, just gas that is very difficult to detect without large, sensitive instruments in space. Planck can only image some of this "dim" matter by overlaying hundreds of images, which cannot detect other baryons (mostly protons) that are not clustered this way. == Rotation Curves around a Line Mass == "Heavy" line mass filaments perpendicular to a galaxy produce rotation curves with constant velocity at any radius. || $ \mu $ || Standard Gravitational Constant || || $ \lambda $ || line mass density, i.e., kg/m || || $ r $ || radius of body from line mass || || $ y $ || vertical offset from mass element || || $ l = \sqrt{ r^2 + y^2 } $ || distance from mass element || || $ b $ || integration substitution variable || || $ a $ || acceleration towards line mass || || $ v $ || orbital velocity around line mass || $ da ~=~ gravity \times cos( angle ) $ $ da ~=~ \Large { { \mu \lambda dy } \over { l^2 } } { r \over l } $ $ a ~=~ \mu \lambda r \Large \int_{-\infty}^{+\infty} { dy \over l^3 } $ substitute $ y = b r $: $ dy = r db $ $ l = \sqrt{ r^2 + y^2 } = \sqrt{ r^2 + b^2 r^2 } = r \sqrt{ 1 + b^2 } $ |
Cold Dark Matter
New Scientist 2017 11 October
Hideki Tanimura at the Institute of Space Astrophysics in Orsay, France
A Search for Warm/Hot Gas Filaments Between Pairs of SDSS Luminous Red Galaxies
Detection of intercluster gas in superclusters using the thermal Sunyaev-Zel'dovich effect
Anna de Graaff at the University of Edinburgh, UK.
There may be no exotic dark matter, just gas that is very difficult to detect without large, sensitive instruments in space. Planck can only image some of this "dim" matter by overlaying hundreds of images, which cannot detect other baryons (mostly protons) that are not clustered this way.
Rotation Curves around a Line Mass
"Heavy" line mass filaments perpendicular to a galaxy produce rotation curves with constant velocity at any radius.
\mu |
Standard Gravitational Constant |
\lambda |
line mass density, i.e., kg/m |
r |
radius of body from line mass |
y |
vertical offset from mass element |
l = \sqrt{ r^2 + y^2 } |
distance from mass element |
b |
integration substitution variable |
a |
acceleration towards line mass |
v |
orbital velocity around line mass |
da ~=~ gravity \times cos( angle )
da ~=~ \Large { { \mu \lambda dy } \over { l^2 } } { r \over l }
a ~=~ \mu \lambda r \Large \int_{-\infty}^{+\infty} { dy \over l^3 }
substitute y = b r :
dy = r db
l = \sqrt{ r^2 + y^2 } = \sqrt{ r^2 + b^2 r^2 } = r \sqrt{ 1 + b^2 }