Are dark matter and dark energy two aspects of a same problem?

Transcription

1 Are dark matter and dark energy two aspects of a same problem? Celine Boehm Cargese, nov-2008 LAPTH, UMR5108, Annecy-le-Vieux

2 Evidence and (cosmo) constraint for dark energy (Francis&Jerome s talks) 7/11/08 Celine Boehm 2

3 1 Some evidence for DM Baryonic matter represents less than 5% of the energy density of the Universe Lensing 7/11/08 Celine Boehm 3

4 Let us focus on DM 7/11/08 Celine Boehm 4

5 Any possible contestation? Rotation curves of galaxies: MOND is an alternative (see Francoise s talk) Nucleosynthesis: No contestation, it is a very strong argument (although most of the baryons are missing) Structure formation: Contestable under specific circumstances Well. but in general difficult to explain without DM Lensing: Contestable under specific circumstances 7/11/08 Celine Boehm 5

6 What kind of DM candidates should we consider? 7/11/08 Celine Boehm 6

7 In absence of direct evidence Astrophysics: MACHOs EROS & MACHO Modifying gravity: What kind of theories? Particle Physics: What kind of candidates? 7/11/08 Celine Boehm 7

8 What theor(y)/(ies) for modifying gravity? 7/11/08 Celine Boehm 8

9 MOND, its extensions and other scenarios MOdified Newtonian Dynamics (MOND) TeVeS (Bekenstein) Other modifying gravity scenarios F(R ) see Nathlie s talk 7/11/08 Celine Boehm 9

10 MOND: suffer from Silk damping; no way to avoid it Bekenstein: Silk damping is counteracted but CMB 3 rd peak is difficult to fit Others: Smaller modifications but tests with solar system 7/11/08 Celine Boehm 10

11 1967: Peebles assumed that objects (galaxies) originate from small energy density perturbations galactic seeds BUT do these fluctuations exist? Latest WMAP 7/11/08 Celine Boehm 11

12 Silk Damping 1968: J. Silk s concluded that if perturbations exist then the content of such perturbations is dominated by baryons, then only a few galaxies can form BUT WHY? vacuum matter Protons and photons have electromagnetic Interactions. Lead to accoustic oscillations when fluctuations enter the sound horizon But eventually photons decouple while protons still interact with photons Too low density to form loads of galaxies Evidence that we need non-baryonic matter Birth of WIMPs (DM) 7/11/08 Celine Boehm 12

13 What kind of DM candidates? Neutral, Weakly-Interacting Massive particles= WIMPS OFTEN SAID: WIMPS =Collisionless particles WIMPS= Cold DM (but neutrinos are WIMPs and HDM, so needs to be a bit careful) But: How collisional can DM be? Can DM be also Warm? (and what would this mean?) 7/11/08 Celine Boehm 13

14 Generalisation of the Silk damping to DM * Free-streaming scale (the relevant scale when DM has no interaction) Free particles Leave the overdense regions Distance travelled depends on the time at which they became free and their velocity * Collisional damping scale Coupled particles Particles leave the fluctuations by following other species Depends on the interaction rate with these other species and number density 7/11/08 Celine Boehm 14

15 Classification of the DM properties Scale factors Decoupling Non-relativistic equality 7/11/08 Celine Boehm 15

16 Example of free-streaming calculations Region I: Hot Dark Matter Mass < MeV Region II: Cold Dark Matter Interaction rate at equality Mass > MeV 7/11/08 Celine Boehm 16

17 Constraints from free-streaming and self-damping Strongly interacting DM Collisional WDM Collisional CDM Collisionless CDM Collisionless WDM Hot DM CB, R. Schaeffer (2001,2004) 7/11/08 Celine Boehm 17

18 Constraints from collisional damping 7/11/08 Celine Boehm 18

19 DM Mixed damping (CB, P. Fayet, R. Schaeffer 2001) (the same as for protons in the tight regime, after the photons decouple) The baryons stay coupled to photons but photons free-stream DM particle neutrino baryon 7/11/08 Celine Boehm 19

20 Constraints from mixed damping 7/11/08 Celine Boehm 20

21 Maximal DM interactions with photons? U = sigma_(dm photon)/sigma_(thomson) Planck could constrain the DM interactions 7/11/08 Celine Boehm 21

22 So in short for what kind of part. phys DM candidates should we consider: 7/11/08 Celine Boehm 22

23 Very light Hot DM = e.g. neutrinos gravity + DM velocity Excluded massive CDM = collisional but wimps SUSY LSP, KK, XDM, MDM,LDM just gravity Very popular Warm DM = collisionless neutrinos with m=1 kev collisional dm with m~ 1 MeV Not popular and yet gravity + DM velocity (+DM interactions) + all sorts (including self-interacting DM) as long as FS and collisonal damping length are not too large 7/11/08 Celine Boehm 23

24 Any other constraint? 7/11/08 Celine Boehm 24

25 1. Relic density 2. Direct Detection 3. Indirect Detection 4. Laboratory 7/11/08 Celine Boehm 25

26 Relic density Hut, Lee-Weinberg (1977) The proportion of DM cannot exceed 100% of the energetic content of the Universe DM + SM matter + DE = 100% 7/11/08 Celine Boehm 26

27 Pure ``cosmology One range of cross sections always give the right relic density It is about cm 2 like weak interactions With a ``Standard Model (heavy neutrinos exchanging heavy gauge bosons), one obtains the following window but that is assuming a cross section that is proportional to the dark matter mass v " m m 2 dm 4 w Pure ``particle physics 7/11/08 Celine Boehm 27

28 The Lee-Weinberg limit: Annihilating DM particles must be heavy with a mass between ]1 GeV- 1 TeV] In agreement with supersymmetry BUT there is one massively important assumption 7/11/08 Celine Boehm 28

29 They took fermionic particles With scalar particles, there is no limit anymore 7/11/08 Celine Boehm 29

30 Lee-Weinberg: v " m m 2 dm 4 w Scalar particles: "v 2 cl c m 2 r 2 F Independent of the DM mass Light particles (MeV) are allowed by the relic density argument 7/11/08 Celine Boehm 30

31 Is the relic density constraint constraining? 7/11/08 Celine Boehm 31

32 Example with SUSY Susy constrained to the bulbe region Ellis et al 7/11/08 Celine Boehm 32

33 7/11/08 Celine Boehm 33 But exceptions to relic density constraint Co-annihilation Resonances Focus point ) ( ) ( ) ( 3 ) ( ) ( 3 0, 0, 0, 2 0, 2 0, 0, 2 0, 2 j j j j i j i ann co j j ann j j j i j i ann co i i ann i i n n n n n n v n n v Hn dt dn n n n n v n n v Hn dt dn " = = # # # # ma ma Mh ~ 2 ma

34 Coannihilations, etc n # ( mt ) 3 / 2 e " m Enables to consider very large neutralino masses Coa interactions enables to reduce the DM number density ~ pure annihilations ~ co-annihilations 7/11/08 Celine Boehm 34

35 Direct detection 7/11/08 Celine Boehm 35

36 Counting rates Direct Detection Principles Inspired from Druckier & Stodolski Goodman&Witten (1985) dn Flux dn = Since Flux = # v $ p = # v = n n S Z A dm dm dt " Z A n a p d $ " a with material M n p and material = $ $ m material dt p p = M material Volume, we have : Type of interactions Needs very massive detector Spin dependent: sensitive to the spin of the nuclei (coherent cross section J(J+1) with J=L+S) Spin independent: insensitive to the spin of the nuclei 7/11/08 Celine Boehm 36

37 Annual modulation Drukier,Freese,Spergel # with # $ 30 km / s ( earth orbital velocity around the Sun ) " = 60 (the inclination of the Earth orbital plane with respect to the galactic plane) w = ( 2 / 365) radian / day t 0 Earth orb = # sun + # the 2nd of June orb cos " cos[ w( t % t (half a year) 0 )] 7/11/08 Celine Boehm 37

38 Direct detection techniques G e 10% energy Ionization WIMP Elastic nuclear scattering G e, Si Credit: V. Sanglard Liquid Xe NaI, Xe Target Light 1% energy fastest no surface effects Heat 100% energy slowest cryogenics CaWO 4, BGO WIMP Al 2 O 3, LiF 7/11/08 Celine Boehm 38

39 SUSY saved by coannihilations, focus point region, Higgs pole Mechanisms used to uncorrelate the relic density criterion from direct detection Soon able to probe neutrinos 7/11/08 Celine Boehm 39

40 Exclude DAMA but DAMA/LIBRA just claimed a 8sigma discovery of an annual modulation signal. 7/11/08 Celine Boehm 40

41 So (apart from DAMA) there is no manifestation of DM candidates in Direct Detection experiments 7/11/08 Celine Boehm 41

42 Indirect Detection 3 types of messengers 7/11/08 Celine Boehm 42

43 7/11/08 Celine Boehm 43 " # $ $ % & " # $ $ % & + ' " # $ $ % & = c r c r r r ( ( " # $ $ % & " # $ $ % & + ' " # $ $ % & = c r c r r r ( ( NFW = Navarro-Frenk-White Moore Halo with a ~ spherical symmetry (triaxial) = n*m

44 4.Particle physics constraints: Indirect detection 1. DM annihilations into 2 photons 2. DM annihilations into cosmic rays/anti matter 3. DM annihilations into neutrinos 4. Radiative decays + decays in cosmic rays/anti matter DM DM -> γ γ DM DM -> e + e -,ppbar.. DM DM -> ν ν 7/11/08 Celine Celine Boehm Boehm 2444

45 How to compute a flux? The basic way (assuming no propagation, no loss): l.o.s r d Production of the particles that one want to detect (the numerical way) (the analytic way) 7/11/08 Celine Boehm 45

46 Propagation How to compute a flux (bis) losses source ( b ( E ) N ( r, E )) Q ( r, E ) 2 t N ( r, E ) = K ( E ) " N ( r, E ) + E + Depends on the magnetic field Boost (hidden in the source term Q(r,E), related to presence of e.g. clumps) Losses ( term in b(e) ) 7/11/08 Celine Boehm 46

47 A SUSY example 7/11/08 Celine Boehm 47

48 Have we seen DM particles already? Perhaps the 511 kev line observed from the centre of the galaxy 7/11/08 Celine Boehm 48

49 Electron/Positron background 7/11/08 Celine Boehm 49

50 Electron/Positron background +uncertainties Fig. 4. Secondary positron flux as a function of the positron energy. The blue hatched band corresponds to the CR propagation uncertainty on the IS prediction whereas the yellow strip refers to TOA fluxes. The dashed curves feature our reference model with the Kamae et al. (2006) parameterization of nuclear cross sections, the Shikaze et al. (2007) injection proton and helium spectra and the MED set of propagation parameters. The MIN,MED and MAX propagation parameters are displayed in Tab. 1. Data are taken from Boezio et al. (2000), Barwick et al. (1997), Alcaraz et al. (2000) and Grimani et al. (2002). 7/11/08 Celine Boehm 50

51 Positron fraction 7/11/08 Celine Boehm 51

52 Proton and anti proton background 7/11/08 Celine Boehm 52

53 PAMELA DATA 7/11/08 Celine Boehm 53

54 But nothing new with anti-proton 7/11/08 Celine Boehm 54

55 Boost factor 7/11/08 Celine Boehm 55

56 So perhaps the high energy positrons reveal dark matter but maybe not.given the antiproton data Could mean that DM annihilates predominantly into electrons, that it is heavier than a few TeV or simply that DM is not responsible for this signal.. 7/11/08 Celine Boehm 56

57 Neutrino detection Neutrino-muon conversion dn ( ) = flux $ surface ( ) $ d# $ R d# = 2 " sin d ν 7/11/08 νµ µ N X For de/dx of the muons, see PDG Celine Boehm 57

58 4.Particle physics constraints: Indirect detection Visible Sky for ANTARES (courtesy Gabrielle Lelaizant ) 3C 279 not observed Mkn 501 RX J CRAB SS433 GX339-4 VELA galactic centre ICECUBE is in the south pole. Cannot see well the galactic centre but still 7/11/08 Celine Boehm Celine Boehm 26 58

59 4.Particle physics constraints: Indirect detection (courtesy Gabrielle Lelaizant ) 7/11/08 Celine Celine Boehm Boehm 2759

60 In the absence of strong evidence for DM signatures in experiments, we may have to reconsider the hypothesis that DM is not a simple substance. So is there a link between DM and DE? 7/11/08 Celine Boehm 60

61 Many people try Spintessence (Boyle, Caldwell,Kamionkowski) Interacting DM-DE (Peebles and Farrar) Phantom cosmology (F(R)) Unified DE-DM model (Bertolami et al) Strongly interacting DM and DE 7/11/08 Celine Boehm 61

62 7/11/08 Celine Boehm 62 Spintessence ), ( 2 1 ), ( ), ( ), ( ), ( t x i e t x R t x i t x t x = + = " " " of function monotically V = ) ( 2 ) ( ' ) ( Rw R V R e t iwt = = Take a complex scalar field Evolves in a potential: Simplest solution are So the field is spinning at a frequency thetadot ) ( ) ( ) ( ) ( 2 1 ) ( 2 1 ) ( ' 3 R R m R V or R R V R V V R R p V R R R a Q R V H R R n " + = = # $ + = + $ + = = + + For general potential: w= (n-2)/(n+2) When n=2, w=0 so DM present Formation of Q-balls. For quartic+quadratic V: If R2 dominates, DM Otherwise if lambda>0 w=1/3 but tends to 0 and if lambda<0, there is a solution where w=0 For potential: -1/3 R 2 V <RV <R 2 V quintessence and decay into Q-balls

63 7/11/08 Celine Boehm 63 Interacting DM-DE b fermionicdm de density contrast y m m cst y i g x d S k V V g x d S " ## # #$ % & & * ] ) ( [ ) ( )] ( 2 1 [ 4,, 4 ' ( ( ) ( = = ( ( = * * They considered small contrast so dm/m is small. However DM acquires its mass thanks to the DE field This varies a bit from the LCDM model

64 Unified DE-DM Bertolami et al L µ" = $ A [ 1 $ ( g #, µ #," 2 ) 1+ ] Generalized Chaplygin gaz (see Hugo s talk) p = " = # " A [ A + a B 3 ( 1+ ) ] 1 1+ Can separate the two components with time and do cosmology Cosmological cst DM DM is still a ~ CDM fluid 7/11/08 Celine Boehm 64

65 Conclusion DM generally treated separately from DE Yet nature of DM remains mysterious Possible positive signal (PAMELA, INTEGRAL) but may favour outsider candidates No detection in DD or collider experiments (indirectly or directly) Connection to DE done by hand in general (except for unified DE-DM?) But DM and DE both present and difficult to find. Is the key in modifying gravity??? 7/11/08 Celine Boehm 65

66 Principle Compton Δ µ 511 kev SPI/INTEGRAL image obtained using this principle e ΔE = Ee-me (electron scattered out) Measures the photon energy Δµ = angle between the 2 photons Where ΔE = E k2 - E k1 = E p2 - E p1 7/11/08 Celine Boehm 66