GH2005 Gas Dynamics in Clusters IV

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GH2005Gas Dynamics in Clusters IV

• Craig Sarazin
• Dept. of Astronomy
• University of Virginia

Cluster Merger Simulation
A85 Chandra (X-ray)
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Cool Cores in Mergers
Cool cores ? high density gas at bottom of deep
potential well Cool cores can survive for some
time in mergers Almost like a solid object moving
through cluster High density ? prominent in X-ray
images Sharp front edge ? very prominent in
Chandra images
Ricker Sarazin
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Cold Front with Merger Bow Shock
Markevitch et al.
1E0657-56
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Mergers Test of Gravitational Physics
1E0657-56
Markevitch et al.
(Red X-rays gas, grey image galaxies,
contours lensing mass gravity) Gas behind DM
Galaxies
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MergersTest of Dark Matter vs. Modified Gravity

• Gas behind DM Galaxies
• DM location of gravity
• Gas location of most baryons
• Whatever theory of gravity, not coming from where
  baryons are
• Require dark matter (not MOND)

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MergersTest of Collisional Dark Matter

• Gas behind DM Galaxies
• Gas collisional fluid
• Galaxies collisionless particles
• Limit on self-collision cross-section of DM

s/m (DM) ? 1 cm2/g lt 5 cm2/g required
for cores in
dwarf galaxies
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MergersTest of Collisional Dark Matter
1E0657-56
Markevitch et al.
Gas behind DM Galaxies ? limit on collisional DM
s/m (DM) ? 2 cm2/g lt 5 cm2/g required
for
cores in galaxies
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Nonthermal Effects of MergersParticle
Acceleration
Supernova remnants shocks at ? 1000 km/s ?
? few of shock energy ?
cosmic ray electrons ECR,e ? 1062 ergs ECR,ion ?
ECR,e

Clusters
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Cluster Radio Halos and Relics
Radio Halo (turbulent acceleration?)
Radio Relics (shock acceleration?)
Coma Govoni et al.
Abell 3667 Röttgering et al.
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Hot Gas in Clusters of Galaxies

• Clusters of galaxies contain 1014 M? of X-ray
  emitting gas with T108 K, ne 0.001 cm-3.
• Most baryonic matter in present day Universe is
  diffuse, hot intergalactic plasma
• Gas is heated by shocks due to cluster mergers,
  with additional heating from SNe and AGNs
• Cluster cooling cores have radio bubbles ?
  interaction of cooling plasma and radio sources
• Complex hydrodynamical structures due to mergers