Transcription

1 WIMP dark matter and the isotropic radio signal Roberto A. Lineros R. Instituto de Física Corpuscular - CSIC/U.

2 Outline Introduction Cosmic ray propagation Synchrotron emission Radio - galactic - extragalactic Conclusions 2

3 A little of history 1933: Fritz Zwicky postulated dark matter in order to explain Coma cluster dynamics as a bound system 3

4 A little of history 4

5 A little of history Coma Galaxy Cluster Virial Theorem Fritz Zwicky Dunkle Materie 5

6 A little of history 60's 70's Vera Rubin studied rotation curves of edge-on galaxies 6

7 Dark Matter Observations support Dark Matter at: Galactic scales Galaxy clusters scales Cosmological scales 7

8 Galactic scales Rotation curve Weak lensing Velocity dispersion of satellite galaxies Velocity dispersion of dsphs Galaxy cluster scales Velocity dispersion of individual galaxies Strong and weak lensing Peculiar velocity flows X-ray emission Cosmological scales CMB anisotropies Growth of structure LSS distribution BAOs SZ effect 8

9 The Standard Model 9

10 The Standard Model Dark Matter 10

11 Dark Matter particle Massive Non baryonic Electrically neutral (*) Stable (**) 11

12 Dark Matter particle Massive Non baryonic Electrically neutral (*) Stable (**) (*) Except Milicharged DM or CHAMPs (**) DM lifetime larger than 10²⁷ seconds (Universe = 10¹⁷ seconds) 12

13 Candidates Adapted from arxiv: Dark Matter 13

14 WIMPs Weakly Interactive Massive Particles 14

15 Candidates Adapted from arxiv: Dark Matter 15

16 WIMPs Big Bang Thermal relic Correct relic abundance for <σv> ~ 1 pb c Mass in GeV-TeV range For WIMPs: 16

17 WIMP Searches D S D D direct detection indirect detection D S S S D D relic abundance S D particle collider astrophysical probes S D D D 17

18 Indirect DM search D S D S Astrophysical activity SM particles Photons Neutrinos Cosmic rays Stable particles Astrophysical Environment 18

19 Cosmic ray propagation 19

20 Cosmic ray propagation NGC891 Radio emission 20

21 Cosmic ray propagation Turbulent magnetic field 21

22 1 14 kpc Cosmic ray propagation 20 kpc Turbulent magnetic field 22

23 1 14 kpc Cosmic ray propagation 20 kpc galactic source Turbulent magnetic field 23

24 Cosmic ray propagation The transport equation describes the evolution of the CR density Sources Time evolution Diffusion Convection Energy evolution Each specie has its own transport equation usually coupled with other CR specie 24

25 Cosmic ray propagation There is some degeneracy in the propagation's parameter space 25

26 Cosmic ray propagation Transport equation Secondaries From spallations Primaries From SNR and pulsars 26

27 Cosmic ray propagation Details in arxiv:

28 1 14 kpc Cosmic ray propagation 20 kpc Dark Matter source DM halo 28

29 Cosmic ray propagation Transport equation Source from DM annihilation Annihilation cross section Annihilation spectrum DM distribution 29

30 Cosmic rays propagation [arxiv: ] 30

31 WIMP Searches in radio 31

32 Synchrotron spectrum FM VHF Wifi 32

33 Synchrotron spectrum FM VHF Wifi 33

34 Observations from 22 to 1420 DRAO: Roger et @820MHz Guzmán et Haslam et al. Berkhuijsen et al al. The isotropic radio signal and WIMP dark CP3-Origins, Odense 2010 Reich and Reich et al

35 Galactic radio 35

36 Galactic radio 36

37 Galactic radio 37

38 Galactic radio 38

39 Constraining Galactic DM We divide Obs & DM skymaps into several patches ~10⁰x10⁰ We calculate an upper bound for (σv) using the most stringent patch in each skymap 39

40 Annihilation into b quarks [arxiv: ] Thermal cross section is reached at ~10 GeV 40

41 Annihilation into muons [arxiv: ] Constraints for DM lighter than ~15 GeV 41

42 Annihilation into W bosons [arxiv: ] Pbar constraints from Delahaye et al. ArXiv: Bounds for W bosons are not so strong 42

43 Extragalactic radio 43

44 Extragalactic radio 44

45 Extragalactic radio 45

46 Source Count Gervasi et al Sources per: unit angle unit of intensity 46

47 Isotropic radio background ARCADE 2 anomaly They have reported an excess in the radio background which is bigger that the expected with known sources Firxen et al. [arxiv: ] Seiffert et al. [arxiv: ] 47

48 ARCADE 2 anomaly PRL 107, (2011), arxiv: The source count is the key to understand the excess Source counts The ARCADE excess needs of a extragalactic population of sources that dominates at low luminosity and have a steep radio spectrum Could WIMPs do the job? intensity 48

49 ARCADE 2 anomaly PRL 107, (2011), arxiv: DM can provide the missing signal However, it is not unique Alternative explanations Faint quasars Radio-quite AGNs Star forming galaxies Unresolved galactic sources(?) More details: Gervasi et al. [arxiv: ] Singal et al. [arxiv: ] 49

50 Beyond the extra-galactic background [arxiv: ] Power spectrum description of the extragalactic DM radio. A full analysis and forecast are very challenging 50

51 Beyond the extra-galactic background [arxiv: ] 51

52 The isotropic radio background revisited [arxiv: ] 52

53 The isotropic radio background revisited [arxiv: ] 53

54 Intensity The method The data position 54

55 Intensity The method The data Model galactic Model isotropic position 55

56 The method Intensity 1st fit position 56

57 The method Intensity Removing residuals larger than 5σ position 57

58 The method Intensity n-1 fit position 58

59 The method Intensity Removing residuals larger than 5σ, again position 59

60 The method Intensity Convergence! position 60

61 Intensity The method position Repeat for every skymap and trace frequency dependence 61

62 Some results mask templates 62

63 The isotropic radio background revisited [arxiv: ] Experimental uncertainties ARCADE2 collab. results Galactic modeling Estimation from Source Counts 63

64 Conclusions The (extra) galactic radio sky gives an alternative way to constrain WIMP dark matter DM radio searches are able to explore regions with thermal cross section i.e. (σv) = 3 x 10 ²⁶ cm³/s Lower frequencies are more suitable to explore light DM candidates, however cross correlation with other observables are required (!) The ARCADE 2 anomaly is still an unresolved issue 64

65 ~ /pages/dark-matter-hunters/

66 Conclusions The (extra) galactic radio sky gives an alternative way to constrain WIMP dark matter DM radio searches are able to explore regions with thermal cross section i.e. (σv) = 3 x 10 ²⁶ cm³/s Lower frequencies are more suitable to explore light DM candidates, however cross correlation with other observables are required (!) The ARCADE 2 anomaly is still an unresolved issue 66

67 Thank you 67

68 Some references [ ] Radio data and synchrotron emission in consistent cosmic ray models T. Bringmann, F. Donato, R. A. Lineros [ ] Possibility of a Dark Matter Interpretation for the Excess in Isotropic Radio Emission Reported by ARCADE N. Fornengo, R. Lineros, M. Regis, M. Taoso [ ] Galactic synchrotron emission from WIMPs at radio frequencies N. Fornengo, R. A. Lineros, M. Regis, M. Taoso [ ] Cosmological Radio Emission induced by WIMP Dark Matter N. Fornengo, R. Lineros, M. Regis, M. Taoso [ ] The isotropic radio background revisited N. Fornengo, R. A. Lineros, M. Regis, M. Taoso 68