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Françoise Combes March, 2019

Alternative models for Dark Matter. Chaire Galaxies et Cosmologie. Abell 2218. Françoise Combes March, 2019. Dark matter at any scale. CMB W b ,W m , W L. Galaxy clusters X-rays, lenses. HI-21cm rotation curves. Ropt. Several kinds of dark matter. Hot (neutrinos)

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Françoise Combes March, 2019

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  1. Alternative models for DarkMatter Chaire Galaxies et Cosmologie Abell 2218 Françoise Combes March, 2019

  2. Dark matter at any scale CMB Wb,Wm, WL Galaxy clusters X-rays, lenses HI-21cm rotation curves Ropt

  3. Several kinds of dark matter Hot (neutrinos) Relativistic at decoupling Cannot form the small structures, if m < 5 keV Cold (massive particles) CDM Non relativistic at decoupling WIMPS ("weakly interactive massive particles") Neutralinos: particle m~100GeV The lightest supersymmetric particle Cold model (CDM) Warm Hot model (HDM)

  4. Why alternative models? CDM Particles not found Problems at galaxy scales Cusp versus core Missing satellites Baryons mostly outside galaxies Observations Versus Simulations CDM

  5. Tully-Fisher scaling relation • fb universal fraction • of baryons= 17% • CDM: « Cold Dark Matter » • standard model • most baryons are not • in galaxies V4 McGaugh et al 2000

  6. The WIMP miracle Possible to obtain the required abundance of dark matter with particles of mass ~100 GeV, with the weak force interaction annihilation rate <sv> ~3 10-26 cm3/s In early Universe, abundance of particules is « frozen », they decouple when their interaction n <sv> ~1/thubble Coincidence: corresponds to the lightest particle of super-symmetry (neutralino) But in LHC: no super-symmetry, No new particle! N more annihilation↓ Time  T

  7. Problems of the standard CDM model • Prediction of "cusps" at the centre of galaxies, not observed in particular absent in dwarf galaxies, dominated by darkmatter • Prediction of a large number of satellites around galaxies The solution could come from the still unrealisticmodeling of physicalprocesses (star formation, feedback), lack of resolution of simulations, or the nature of darkmatter? The dark matter profiles are not universal predicted observed Cusp/core

  8. Missing satellitesFornax, Leo I, Sculptor, Leo II, Sextans, Carina, Ursa Minor, CanesVenatici I, Draco 9-10 satellites with Lv > 105L MW M* / fb MDM Low Surface Brightness galaxies dominated by dark matter These dwarf are not formed in CDM simulations Mtot

  9. Ly-a: constraints on m(warm) 25 quasars z >4: spectra obtained at Keck (Viel et al 2013) Ly-a forest and comparison with simulations mWDM > 3.3 kev (2s) WDM, mX > 4.65 keV thermal relics ms > 29 keV non-resonant production Yeche et al (2017)

  10. Primordial Black holes as DM RS = 2GM/c2 = 3(M/M) km ρS = 1018(M/M)-2 g/cm3 Only form in early Universe, cosmological density ρ ~ 106(t/s)-2g/cm3 PBHs should form with horizon mass at formation Mhor(t) in ct MPBH ~ c3t/G =10-5g at 10-43s (minimum) 1015g at 10-23s (evaporating now) 1M at 10-5s (maximum) PBH formation requires strong inhomogeneities in the early inflation, and recollapsing local regions +phase transition, bubble collisions, collapse of strings or domain walls e.g. Carr et al 2010, 2016

  11. Exclusion of the last window for PBH Encounter of the PBH with a neutron star  Destruction of the neutron star Cotner & Kusenko 2017 Pani & Loeb 2014

  12. Primordial Black holes g, yellow: neutron capture, GW b = rPBH/rtot For M~1015g too many g-rays produced M Since PBH form in the radiative era, they can be considered as non-baryonic, and =CDM However, their mass is limited by MACHOS, EROS experiments Small masses evaporate Gutierrez et al 2017

  13. Candidates for the dark matter New physics, beyond the standard model SM Champs (charged DM) D-matter Cryptons Self-interacting Superweakly interacting Braneworld DM Heavy neutrino Neutralino (WIMP) Messenger States in GMSB Branons Chaplygin Gas Split SUSY Primordial Black Holes Mirror Matter … Kaluza-Klein DM in UED Kaluza-Klein DM in RS (Randall-Sundrum) Axion Axino Gravitino Photino SM Neutrino Sterile Neutrino Sneutrino Light DM Little Higgs DM Wimpzillas Cryptobaryonic DM Q-balls

  14.  Fuzzy dark matter Cusps exist in galaxy clusters, but not in galaxies In dwarf galaxies, cores of ~1kpc Bosons generated in non-thermal mechanisms  axions (ALP, Marsh 2016) cold particles, which can collapse BEC “Bose-Einstein condensate”, macroscopic state at low T • Finite mass, very small, l de Broglie, λ comp = h/mav λ comp = 1-2 kpc • In fact λ comp ~ 1-2 kpc for ma = 10- 22 eV , and v~10km/s For these masses ma = 10- 22 eV, the wavy oscillations prevent the small scale structures below Mcut = 3 108 m22-3/2 M (Hui et al 2017).

  15. Simulations AMR: eq. Schrödinger- Poisson Core= soliton, Halo= clumpy aspect + wavy (Schive +2014)

  16. Quantum interferences: 9 orders of magnitude Schive et al 2014

  17. Radial density profile • The waves produce • interferences and granules • depending on time • Resolution 50pc • Dwarf galaxies could have • only one soliton, with high • fluctuations Lin, Schive et al 2018 No cusp, but a drop just after the soliton! Relatively stable profile

  18. Present constraints N CDM • Fluctuations of rDM on times shorter • than the gravitational time-scale • heating of the stars, for instance old • dwarf galaxy Eridanus II • m> 0.6 10-19 eV • Marsh & Niemeyer 2018 • An even shorter time-scale, in 1/m or month-scale • due to the coherent variations of pressure, Compton-scale fluctuations • gravitational background, stochastic but monochromatic • From pulsars timing PTA: 26 pulsars 2004-16, Porayko et al 2018 • nanoHz frequencies GW, for m<10-23eV, density < 6 Gev cm-3 • in the near future (FAST/SKA) 0.05Gevcm-3= 10% of the DM FDM 10-22 10-21 10-20

  19. Modifying the gravity • Newton law is applicable everywhere • Dark matter is necessary, dark energy as well • But 95% of the Universe is a dark sector, which appears only by its • gravitationnal manifestations • Possibility of a modified law of gravitation! DM: to be or not to be

  20. MOND = MOdified Newton Dynamics Atweakacceleration a << a0 MOND regimea = (a0aN)1/2 a>>a0Newtonian a = aN a0 = 10-10 m/s2 ~ 10-11g Milgrom (1983) • Asymptotically • aN ~ 1/r2  a ~ 1/r •  V2 = cste • Covariant theory: TeVeS • Gravitationnal lenses a0 = 10-10 m/s2 Mdyn/Mvis = f(aN/a0) V2obs /Vb2 = a /aN Acceleration aN (pc/Myr2)

  21. N1560 N2903 stars gas gas stars TF relation Success at weak surface densities • <S0~150 M/pc2, the criticalacceleration a0 • In particulardwarf galaxies The rotation curves of all galaxy types a<<a0 a> a0 a<<a0

  22. Influence of the dark halo ? Dynamics of galaxies, Formation of spirals and bars Stars Gas observations TeVeS covariant theory However unstable And ruled out by gravitational waves simulations

  23. The bullet cluster Gas X Rare case of violent collision, allowing to separate components  Limit on sDM/mDM < 1 cm2/g For modified gravity, need of non-collisionnal matter: neutrinos or dark baryons Masse totale V=4700km/s (Mach 3)

  24. Have we identified all the baryons? • 6% in galaxies (stars); 3% in galaxy clusters, X-ray gas • ~18% in the Lyman-alpha forest (cosmic filaments) • ~10% in the WHIM (Warm-Hot Intergalactic Medium) 105-106K • OVI lines • 63% are not yet identified! The majority are not in galaxies

  25. Theories Einstein - aether The theories “Einstein æther”, ou æ-theories, are covariant théories with modified general relativity Tensor + vector (or scalar) field, of time regime, called aether A revival of gravitational ether of 19th century! To solve quantum gravity and dark energy problems Existence of a privileged frame, rest-frame of ether these theories violate Lorentz invariance Difficult to represent static black holes (no horizon)

  26. Emergent gravity The gravity is not a fundamental force, but a maximisation of entropy Entropy and thermodynamics of horizon (Bekenstein-Hawking) Acceleration and temperature (Unruh) Holographic theory (Gerard ‘t Hooft) Verlinde E.: 2010, On the origin of gravity and Newton laws Verlinde E.: 2016, Emergent gravity and the dark Universe

  27. Gravity as an entropic force At the microscopic level: a large number of degrees of freedom They are not visible, but relevant for the macroscopic physics Gravity would come automatically from the fact that space occupied by this information, these microscopic degrees of freedom, depend on macroscopic variables  emergent gravity Polymere molecule A force occurs since the system tends to icrease its entropy (Verlinde 2011)

  28. Quantum intrication Intricated entropy of quantum vacuum Intrication for two systems A, B, when their wave function is mixed (tested on 100km) One can define the max of intrication entropy: maximum when systems are completely mixed The variations of intrication entropy, due to the presence of matter can explain the emergence of gravity (Verlinde 2016) The geometry of space-time represents the structure of intrication at microscopic level (Maldacena and Susskind, 2013, Van Raamsdonk 2010)

  29. This principle retrieves the MOND dynamics The entropy is diffuse in the universe as the dark energy Dark matter, when S < a0/8pG, the apparent dark matter or d=4 Or gD2 = gN a0/6, which is the MOND relation (Milgrom 1983) Hypothesis: we live in a de Sitter space L; Wb~5% baryons L=0.95 WD2 = 4/3 Wb WD= 0.26 The L corresponds to the intrication of microscopic elements This boost of gravity (dark matter) occurs whenthe entropy of quantum intrication of matter falls below the entropy of dark energy

  30. Emergent gravity vs MOND in clusters Gravity is boosted , as soon as acceleration << a0 ~c H gD= sqrt (a0 . gB/6), alors g= gD + gB The acceleration becomes 2 to 3 larger than in MOND In galaxy clusters g= gB (1+1/x) with x2= 6/(cH) gB/(1+3 dB)

  31. Test of gravitational lenses KIDS: VST-ESO KiloDegree Survey + GAMA spectro survey 33 000 galaxies ESD=Excess surface density (R) Compatible with apparent DM due to emergent gravity Brouwer et al 2016

  32. The dark matter puzzle Why alternative models? Problems of standard dark matter models at galaxy scale (cusp, missing satellites, ejection of baryons) Exotic particles still unknown, beyond standard model Masses between 10-22 eV (axions) & 1012 eV (WIMPs) searched for during 33yrs Fuzzy Dark Matter Neutrinos, contrained by Ly-a : mX > 4.65 keV & ms > 28.8 keV  modified gravity, 5th force, quantum gravity, entropic force

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