Searching for WIMPs in deep radio observations of Gl Galactic dsphs

Transcription

1 Searching for WIMPs in deep radio observations of Gl Galactic dsphs m x = 10 GV GeV XX e+/e D o = 0.1*MW Excluded d( (2σ) 05deg 0.5 <ov> th Kristine Spekkens (RMC) Brian Mason (NRAO), James Aguirre (UPenn), Bang Nahn (Colorado), Beth Willman (Haverford), Aravind Natarajan, Jeff Peterson (CMU)

2 Searching for WIMPs in deep radio observations of Gl Galactic dsphs 05deg 0.5 Outline: m x = 10 GV GeV XX e+/e D o = 0.1*MW Searching for WIMPs in deep radio observations Excluded (2σ) Constraints on <ov> from radio non detections Challenges and future prospects Punchline: <ov> th Indirect radio WIMP searches are highly complementary to those at higher energies Kristine Spekkens (RMC) Brian Mason (NRAO), James Aguirre (UPenn), Bang Nahn (Colorado), Beth Willman (Haverford), Aravind Natarajan, Jeff Peterson (CMU)

3 Hunting for WIMPs Indirect WIMP searches look for SM annihilation products: Weakly interacting thermal relics: <ov> th ~ 2x cm 3 /s Colafrancesco 2006

4 Hunting for WIMPs Indirect WIMP searches look for SM annihilation products: Weakly interacting thermal relics: <ov> th ~ 2x cm 3 /s Neutral pion decays: annihilation flux depends on WIMP properties and dark matter distribution

5 Dwarf spheroidal galaxies: ideal targets 30 Bernhard Hubl

6 Dwarf spheroidal galaxies: ideal targets σ (k km/s) Why dsphs? Well modelled kinematics: high dark matter density No evidence for gas, dust, recent star formation Walker 2012 R (pc) 30 Annihilation rate relatively high, signal relatively clean Bernhard Hubl

7 Upper limits for dsphs from Fermi

8 Upper limits from Fermi <ov> th ~ 2 x cm 3 /s Ackermann Individual dsphs exclude ~ few<ov> th at 10 GeV, ~ 10<ov> th at 100 GeV

9 Hunting for WIMPs Indirect WIMP searches look for SM annihilation products: Weakly interacting thermal relics: Weakly interacting thermal relics: <ov> th ~ 2 x cm 3 /s

10 Hunting for WIMPs Indirect WIMP searches look for SM annihilation products: Weakly interacting thermal relics: <ov> th ~ 2x cm 3 /s Neutral pion decays: annihilation flux depends on WIMP properties and dark matter distribution

11 Hunting for WIMPs Indirect WIMP searches look for SM annihilation products: Weakly interacting thermal relics: <ov> th ~ 2x cm 3 /s Charged pion decays: annihilation flux depends on WIMP properties and host td dark matter distribution and host diffusion properties

12 WIMPs in dsphs: prediction for Draco Expected radio synchrotron annihilation signal: bright! Draco m 9 bea Colafrancesco extended! d!

13 WIMPs in dsphs: prediction for Draco Expected radio synchrotron annihilation signal: bright! Draco m 9 bea Optimistic! [x100] Colafrancesco extended! d! Spekkens+ 2013: map extended emission with GBT, excise confusing background sources with VLA

14 Deep radio maps of nearby dsphs GBT data Draco ν = 14GH 1.4 GHz, Stokes I 4 deg x 4 deg stars 1 deg

15 Deep radio maps of nearby dsphs GBT data Draco ν = 14GH 1.4 GHz, Stokes I 4 deg x 4 deg 1 deg

16 Deep radio maps of nearby dsphs NVSS data Draco ν = 14GH 1.4 GHz, Stokes I 4 deg x 4 deg 1 deg

17 Deep radio maps of nearby dsphs NVSS GBT NVSS data data Draco ν = 14GH 1.4 GHz, Stokes I 4 deg x 4 deg 1 deg

18 Deep radio maps of nearby dsphs GBT NVSS data Draco ν = 14GH 1.4 GHz, Stokes I 4 deg x 4 deg x 1 deg Spekkens+ 2013

19 Searching for WIMPs in deep radio maps Spekkens+ 2013

20 Searching for WIMPs in deep radio maps Stokes I Spekkens+ 2013

21 Searching for WIMPs in deep radio maps Stokes I Foregrounds Spekkens+ 2013

22 Searching for WIMPs in deep radio maps Stokes I

23 Searching for WIMPs in deep radio maps Stokes I input halo processed halo Pitfalls of data baselining: 1. flux filtering 2. curvature bias

24 Searching for WIMPs in deep radio maps Stokes I Foregrounds input halo processed halo Pitfalls of data baselining: 1. flux filtering 2. curvature bias

25 Searching for WIMPs in deep radio maps Stokes I Spekkens+ 2013

26 Searching for WIMPs in deep radio maps Stokes I Spekkens+ 2013

27 Searching for WIMPs in deep radio maps Compare to prediction: Stokes I Spekkens+ 2013

28 Searching for WIMPs in deep radio maps Compare to prediction: Stokes I Account for processing: input halo processed halo Spekkens+ 2013

29 Searching for WIMPs in deep radio maps Set #1 : log<ov>= 23.2 Set #2 : log<ov>= 24.9 Set #1 : log<ov>= 23.6 Set #2 : log<ov>= 24.9

30 Searching for WIMPs in deep radio maps Set #1 : log<ov>= 23.2 Set #2 : log<ov>= 24.9 Set #1 : log<ov>= 23.6 Set #2 : log<ov>= 24.9 Fermi results log<ov>= 24.9 set #2 limits it similar il to Fermi for individual id dsphs Ackermann+ 2011

31 Hunting for WIMPs Indirect WIMP searches look for SM annihilation products: Weakly interacting thermal relics: <ov> th ~ 2x cm 3 /s Charged pion decays: annihilation flux depends on WIMP properties and host td dark matter distribution and host diffusion properties

32 Complications: charged particle diffusion Charged particle diffusion in dwarfs poorly constrained Extrapolate from Milky Way and galaxy cluster values: Set #1, set #2 (roughly) bracket range values allowed for the Milky Way Spekkens NASA/JPL

33 Complications: charged particle diffusion Charged particle diffusion in dwarfs poorly constrained Extrapolate from Milky Way and galaxy cluster values: Set #1, set #2 (roughly) bracket range values allowed for the Milky Way Set #1 : log<ov>= 23.2 Set #2 : log<ov>= 24.9 Spekkens Smaller diffusion constant preferred for dsphs

34 Complications: magnetic fields Magnetic fields in dsphs are unconstrained: Equipartition Faraday rotation Bernhard Hubl Van Heesen SKA.org

35 Complications: magnetic fields If dsphs and dirrs have common history, and dirrs have B ~ 5 10 μg Mayer Bernhard Hubl B ~ 1 μga reasonable estimate for dsphs?

36 Hunting for the ISM in dsphs: HI M HI limits from the GBT: UMaII Coma M HI < 60 Mo M HI < 110 Mo Will1 stars: V = 14.1 km/s, σ = 4.0 km/s (Willman+ 11) Probable Wil1 stars 1.5 o 1 kpc 23.7 km/s 21.1 km/s 18.5 km/s 6 r h 16.0 km/s 13.4 km/s 10.8 km/s A Galactic HI cloud coincident c with Will1?

37 Sophisticated Modelling is Underway Predicted annihilation flux for UMaII: m x = 10 GeV m x = 200 GeV 1.4 GHz D o = 0.1*MW 1 μg <ov> th I (mjy/ /arcmin 2) r (deg) A. Natarajan, KS et al, in prep r (deg)

38 Sophisticated Modelling is Underway Sample exclusion curves: m x = 10 GeV XX e+/e D o = 0.1*MW Excluded (2σ) m x = 200 GeV XX bbar D o = 0.1*MW Excluded (2σ) <ov> th <ov> th Exclude <ov> th for m x < 20 GeV, B > 0.5 μg, D o < MW, leptonic chans A. Natarajan, KS et al, in prep

39 Complications: Magnetic Fields Magnetic fields in dsphs are unconstrained:

40 And we can do better input halo processed halo 1. Larger, offset maps 2. Expanded dsph sample Should gain a factor of a few for leptonic channels Should gain a factor of a few for leptonic channels, order of magnitude for hadronic channels

41 Conclusions WIMP annihilations in dsphs should produce degree scale radio synchrotron halos We searched for this signature in deep GBT maps of 4 dsphs Upper limits on <ov> from our maps are commensurate with those from Fermi, with scope for improvement Indirect radio WIMP searches are highly complementary to those at higher h energies