A galaxy like the Milky Way or Andromeda has a total visible mass of about 61010 Msun. A galaxy like the Milky Way or Andromeda has a total visible mass of about 61010 Msun


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A galaxy like the Milky Way or Andromeda has a total visible mass of about 61010 Msun.

  • A galaxy like the Milky Way or Andromeda has a total visible mass of about 61010 Msun.

  • - rotation velocity is ~220 km/sec

  • - radius about ~30 kpc

  • Newton:  total mass: 3.31011 Msun  ~5 times more mass than visible

  •  Local density 0.3- 0.4 GeV/cm3



















“WIMP”= “Weakly Interacting” Massive Particles

  • “WIMP”= “Weakly Interacting” Massive Particles

  • G. Altarelli: « still most optimal candidates !»

  • Arguments in the 1980’s:

  • Need for Cold Dark Matter from Large Scale Structures

  • Very good Particle physics candidate: SUSY LSP

  • Weak neutrino size cross sections expected which our detectors Ge, NaI were sensitive to…



“WIMP”= “Weakly Interacting” Massive Particles

  • “WIMP”= “Weakly Interacting” Massive Particles

  • Assumption: DM= Relic Particles from Big Bang

  • If DM survives today

  • rate annihilation < rate expansion

  • If (rate annihilation << rate expansion),

  • too much DM today

  • At « freeze out »

  • <  v > ~ 10-26/  h2 cm3/s

  • Scale of weak interactions !

  • Coincidence with W, Z physics?

  • Searches for massive neutrinos cross sections exclude cross-section < 0.1 













CoGeNT background

  • CoGeNT background

  • < 0.1 c/keV/kg/day !



Ton scale liquid Xenon two phase (liquid and gas) TPC

  • Ton scale liquid Xenon two phase (liquid and gas) TPC

  • Project lead by SJTU











Ling+ 2009 Dark Matter Direct Detection Signals inferred from a Cosmological N-body Simulation with Baryons

  • Ling+ 2009 Dark Matter Direct Detection Signals inferred from a Cosmological N-body Simulation with Baryons

  • Fin



No convincing signal todate !

  • No convincing signal todate !



















Preferred paradigm:

  • Preferred paradigm:

  • Most N-Body simulations use stable CDM halos as seed for structures:

  • structures evolve, merge and cluster

  • DM halos

    • cuspy density profiles,
    • Triaxial halos
    • - central density depends on the mass of the halo.






- Virialized structures of DM down to scales of ∼ 107 − 109 M⊙ halos.

  • - Virialized structures of DM down to scales of ∼ 107 − 109 M⊙ halos.

  • (modelling of lens galaxies)

  • Milky Way dwarf galaxies:

  • Most DM dominated structures known

  • half-light radii of ∼ 30 − 800 pc, ∼ 106 − 108 M⊙ DM

  • with mass-to-light ratio ∼ 10 − 4000 M/L⊙







Salucci & Frigerio Martins, 2009

  • Salucci & Frigerio Martins, 2009





Salucci &

  • Salucci &

  • Frigerio Martins 2009



Oh et al. 2011

  • Oh et al. 2011









DM particles might interact with themselves or other new particles, mediated by new, dark gauge bosons.

  • DM particles might interact with themselves or other new particles, mediated by new, dark gauge bosons.

  • Interactions affect the structures of DM halos:

  • DM scatters  energy and angular momentum transfers

  • For hard-sphere elastic scattering,

  • observations of the structure of galaxy clusters

  • constraints σ /m





Strong constraints :

  • Strong constraints :

  • Charged (CHAMPS) or small electric or magnetic dipole moment

  • coupling to the photon-baryon fluid before recombination,

  • alter the sub-degree-scale of CMB and matter power spectrum.

  • Cf

  • - Sigurdson+ , Dark-matter electric and magnetic dipole moments, (2004);

  • - McDermott, H.-B. Yu, & K. M. Zurek, Turning off the lights: How dark is dark matter? (2011)





Stable WDM looks like stable CDM on scales> 10 Mpc,

  • Stable WDM looks like stable CDM on scales> 10 Mpc,

  • - WDM create a cutoff in the matter power spectrum

  • At late times, the evolution of the matter power spectrum is more subtle as halos form.

  • Large WDM halos are virtually indistinguishable from stable CDM halos

  • somewhat less concentrated,

  • smaller halos, fluffier and less cuspy than CDM halos.

  • The subhalo mass function drops significantly on mass scales corresponding to that cutoff scale.

























Ma Chung Pei, Chang, P., Zhang, 2009

  • Ma Chung Pei, Chang, P., Zhang, 2009





Eg, Belokurov et al, 2010

  • Eg, Belokurov et al, 2010





































Galaxy evolution alters DM halos and the matter power spectrum .

  • Galaxy evolution alters DM halos and the matter power spectrum .

  • Rudd, Zentner & Kravtsov, Effects of Baryons and Dissipation on the Matter Power Spectrum (2008);

  • Pedrosa,Tissera, & Scannapieco, The joint evolution of baryons and dark matter halos, (2010);

  • Scannapieco +, The Aquila Comparison Project: The Effects of Feedback and Numerical Methods on Simulations of Galaxy Formation, arXiv:1112.0315.

  • Most of the simulations (even today) are DM-only

  • - DM halos extremely sensitive to the implementation of the galaxy physics in the codes.

  • - DM halo morphologies and galaxy properties need resolutions: giant molecular cloud (GMC) sized regions .

  • But a lot of concern/work in the last 3 years.





Semboloni+ (2011)

  • Semboloni+ (2011)

  • Van Daalen+(2011)

  • Shale + :OWLS simulation

  • Consequences on WL

  • cosmological parameters fits



Semboloni et al. 2011

  • Semboloni et al. 2011















Not so many models any more, but still… some are still doubting:

  • Not so many models any more, but still… some are still doubting:

  • eg http://www.astro.uni-bonn.de/~pavel/kroupa_SciLogs.html

  • Famaey & Mc Gaugh Living Reviews in Relativity, vol. 15, no. 10 2012

  • - MOND- Milgrom /TEVES-Beckenstein needs neutrinos to explain Bullet Cluster…

  • - MOG : Moffat and collaborators

  • Scalar-Tensor-Vector Model of gravity : “few parameters can explain away DE and DM”.



Local Universe:

  • Local Universe:

  • Velocity analysis

  •  local density ~ 0.07-0.08

  • Dwarf galaxies: observed ones seem to be

  • Tidal dwarf galaxies not expected to be dominant with DM models but seem to be observationnally in disk of Milky Way and Andromeda

  • How representative is it?



- Extension to GR:

  • - Extension to GR:

  • in simplest CARTAN model :

  • (eg, Schucker and Tilquin)

  • Lambda/DE still needed but… DM reduced (to zero?)

  • Difficulties with many extensions

  • eg Gauss theorem not valid, pathologies…



Astrophysical observations

  • Astrophysical observations

  •  existence of non baryonic Dark Matter

  • N-Body simulations and Observations of LSS

  •  existence of not-hot DM?

  • . Many problems with CDM simulations can be solved with

  • O(1keV) WDM or Baryon physics ?



We now measure with precision the extent of our ignorance !

  • We now measure with precision the extent of our ignorance !




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