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This article discusses two "new" features of matter - neutrinos and dark matter - and their role in structure formation. Topics include the types of dark matter, modeling lensing in Abell 1689, and the properties of dark matter particles. It also explores the hydrodynamics of galactic and cluster dark matter and the concept of gravitational hydrodynamics.
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Neutrino hot dark matter and hydrodynamics of structure formation:Two “new” features of matter Dr. Theo M. Nieuwenhuizen Institute for Theoretical PhysicsUniversity of Amsterdam Harvard Smithsonian Center for Astrophysics 22 Jan 2010
Outline Two types of dark matter A modeling of lensing in Abell 1689 Mass, properties, name of DM particle Dark matter condensation on cluster; reionization Galactic dark matter: Gravitational hydrodynamics
The two types of dark matter • Total mass of Universe: 4-5% baryons, 20-25 % dark matter, • 70-75% dark energy • Galactic dark mater: Oort 1931Detected by rotation curves, dwarf galaxies • MACHOs: Massive Astrophysical Compact Halo Objects: Hydrodynamics: Milli Brown Dwarfs consisting of baryons • Cluster dark matter: Zwicky 1932Detected from rotation curves, by lensing • WIMPs Weakly Interacting Massive Particles • The dark matter of galaxy clusters is non-baryonic. • Not MACHOs or WIMPs but MACHOs and WIMPs !!
Abell 1689 galaxy cluster • Nearby z = 0.184 • Total mass • Luminous mass • Baryon poor • Einstein ring
Incomplete Einstein ring at 100/h kpc Abell 1689 Center Dark matter acts as crystal ball
Abell 1689X-rayemitting gasT=10 keV =1.16 10^8 KThreecomponents:Dark matterGalaxies Gas
Hubble, after last repair May 2009 • Galaxycluster • Abell 370 • Strongest • gravitation lens: • 20 times stronger than A1689
Cowsik&McClelland 1973 Treumann,Kull&Bohringer 2000 Nieuwenhuizen 2009 Theory • Assume that DM comes from non-interacting fermions in their common gravitational potential • Mass m, degeneracy g; g = 2 (2s+1) #families • Isothermal model for fermions • Isothermal model for Galaxies and X-ray gas • Virial equilibrium: • 30% solar metallicity
Fit to A1689 lensing data of Tyson and Fischer ApJ 1995Limousin et al, ApJ 2007averageprojectedmass radius
The mass of the dark matter particle small statistical error 2% reduced Hubble parameter Previous estimates and searches: keV, MeV, GeV, TeV: excluded Additional CDM component: excluded = number of available modes in cluster
What is the dark matter particle? The dark matter fraction Early decouplers have small g:Not gravitinos, neutralinos, X-inos Not bosons, e.g. axions Match possible to WMAP5 for =12 (anti) neutrinos, left+right-handed, 3 families: g = 2*2*3=12 mass = 1.45 eV Neutrino oscillations cause small mass differences, 0.001 eV or less SuperNovae Riess 09: h=0.74, Macrolensing: h=0.65
Neutrinos in the cluster Thermal length visible to the eye Temperature is low Smaller than would-be momentum temperature T_p=1.95 K Larger than would-be energy temperature T_E=0.0001 K Typical speed is non-relativistic, v = 490 km/s Local density can be enormous: in Abell center: one billion in a few cc
The biggest quantum structure in the Universe normalized density: # neutrinos per cubic thermal wavelength per degree of freedom N>1: quantum degenerate nu’s N=1: quantum-to-classical crossover at r = 505 kpc = 1.6 million light year d = 2r = 3.2 million light year That is pretty big …
Incomplete Einstein ring at 100/h kpc Abell 1689 Center
Temperature of gas: 10 keV=10^8 K Virial T of alpha-particles overlaps with it. Log(Mass) Virial equilibrium assumed; only amplitude adjusted Log(r/kpc) Cluster radiates in X-rays like a star in light. Radiated energy supplied by contraction, as in stars.Radiation helps to maintain virial equilibrium.
Why isothermal (virial) equilibrium? • Lynden Bell: violent relaxation, faster than collisional • Relaxation in time-dependent potential:every object (individual particle, galaxy) exchanges energy with the whole cluster • Iff phase space density becomes uniform, then Fermi-Dirac distribution • X-ray radiation helps to maintain the virial state, as in the sun
CDM or HDM? • Cold Dark Matter: heavy particles already clumped at decoupling z=1100 • But light neutrinos are free streaming until trapped by galaxy cluster • Free streaming • Crossover when Newton force of baryons matches Hubble force Hp: z = 6 - 7 • Then cosmic voids loose neutrinos and become empty • This heats the intracluster gas up to 10 keV, so it reionizes, without heavy stars • Hot Dark Matter paradigm agrees with gravito-hydrodynamics
Gravitational hydrodynamics • At decoupling: photon mean free path = 10^(-5) pc << horizon • (Silk damping) • Step 1: In the plasma • Effect of viscosity important below z = 5000 • Instability in plasma: proto-voids & proto-galaxy-clusters • Size of proto-voids*(z+1) = 40 Mpc now • 13.6 eV recombination energy gives CMB T-fluctuationsof sub-Kelvin
Gravitational hydrodynamics II • At decoupling: galaxies; Jeans clusters 40,000 solar mass • Some Jeans clusters developed into globular star clustersOthers were used for ordinary stars • Most still exist and are dark. These Jeans clusters act as isothermal “particles” forming the galactic dark matter • Explains flattening rotation curves, Tully Fisher relation • Explains galaxy mergers • Milli-lensing “CDM” subhalos explained as Jeans clusters • (Dwarf) galactic DM does NOT exclude neutrino DM
Antennae galaxies: • Two colliding galaxiescome within each othersdark matter sphere. • Along their trajectories they transform severalcold Jeans clusters intoyoung globular star clusters.
NGC-2623: Two galaxies inside each others dark matter? Jeans clusters warmed: new stars in young star clusters
Gravitational hydrodynamics III • At decoupling: fragmentation of Jeans clusters in • milli brown dwarfs (MBDs) of terrestrial weight. • Thousands of frozen MBDs observed in microlensing • at unit optical depth (Schild 1996, 1999) • 40,000 of heated MBDs in planetary nebulae counted in Spitzer infrared. Connected to hydrodynamics by Gibson&Schild 98-08 • Extreme Scattering Events: Earth-Jovian gas clouds observed in radio. Walker&Wardle 98: May be good fraction of galactic mass • Multiple imaging of pulsars: by MBDs in Jeans clusters • Explanation of H-alpha forest absorption lines • N,Gibson,Schild,EPL (2009) 0906.5801
Helix planetary nebula • Star exploded • Became white dwarf • Ca 40.000 “cometary knots” in radio • = proto-gas balls • Ca 1 earth mass • Galactic dark matter = gas balls of earth mass: Macho’s
Summary • Observed DM of Abell 1689 cluster explained by thermal fermions of eV mass.keV, MeV, GeV, TeV, PeV excluded. Thermal bosons (axions) excluded. • Fitting with global dark matter fraction: 6 active + 6 sterile (anti-)neutrinosMass about 1.45 eV, depends on h • Gas temperature 10^8 K = alpha-particle temp., gas profile matches automatically • Free flow into potential well occurs at z = 6 - 7. Causes reionization, without heavy stars • Neutrino Hot Dark Matter challenges Cold Dark Matter (CDM). • Dark matter particle was not (and should not be) observed in searches • ADMX, ANAIS, ArDM, ATIC, BPRS, CAST, CDMS, CLEAN, CRESST, CUORE, CYGNUS, (DAMA), DAMIC, DEEP, DRIFT, EDELWEISS, ELEGANTS, EURECA, GENIUS, GERDA, GEDEON, FERMI-GLAST, HDMS, ICECUBE, IGEX, KIMS, LEP, LHC, LIBRA, LUX, NAIAD, ORPHEUS, PAMELA, PICASSO, ROSEBUD, SIGN, SIMPLE, UKDM, VERITAS, XENON, XMASS, ZEPLIN. AMANDA, ANTARES, EGRET. • Neutrino mass tested in 2015 in Katrin search between 0.2 eV – 2 eV
Summary II • Hydrodynamics is important before and at decoupling • Predicts structure formation from baryons without CDM trigger • Explains a wealth of observations • Hydrodynamic structure formation is top-down • So CDM cannot be right and its particle has not been found • Even for the CMB peaks, it offers no explanation for the scatter of unbinned data, or for the regime l=3000-8000. Turbulence does. • Hydrodynamics connects structure formation to turbulence.
Do non-relativistic neutrinos constitute the dark matter? Th. M. N. Europhysics Letters 86 (2009) 59001 Gravitational hydrodynamics of large-scale structure formationTh. M. N., Carl H. Gibson, Rudy E. SchildEurophysics Letters 88 (2009) 49001
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