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Searches for dark matter subhaloes with wide field Cherenkov telescope surveys

Searches for dark matter subhaloes with wide field Cherenkov telescope surveys. J-F. Glicenstein , P.Brun , E.Moulin (IRFU- Saclay ) J.Diemand (ITP-Zurich) Phys Rev D,83, 015003 (2011). Image courtesy of Via Lactea Project: http://www.itp.uzh.ch/~diemand/vl/. Outline.

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Searches for dark matter subhaloes with wide field Cherenkov telescope surveys

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  1. Searches for dark matter subhaloes with wide field Cherenkov telescope surveys J-F. Glicenstein, P.Brun, E.Moulin (IRFU-Saclay) J.Diemand (ITP-Zurich) Phys Rev D,83, 015003 (2011) Image courtesy of Via Lactea Project: http://www.itp.uzh.ch/~diemand/vl/

  2. Outline • HESS flux sensitivity map (Galactic plane) • Search for clumps in HESS galactic plane survey • CTA flux sensitivity map (Galactic plane) • predictions for clumps in CTA galactic plane survey • conclusion Searches for DM subhaloes with Cherenkov telescopes surveys

  3. Indirect dark matter search strategy WIMP annihilation flux into rays observed in solid angle : fAP: dark halo model particle model • Astrophysical factor: • dN/dE given by a particle model neutralinos • DW: assumes point source search

  4. Signal boosts • astrophysics: • unresolvedsub-clumps • particle physics: • Sommerfeld effect: • effective low velocity dispersions • resonances at: • Internal Brehmstrahlung • annihilation to W+W-,ff (c heavy higgsino-like) relative velocity b FSR IB

  5. The H.E.S.S. survey of the Galactic plane F.A. Aharonian et al (HESS) , ApJ. 636, 777 (2006) Searches for DM subhaloes with Cherenkov telescopes surveys

  6. Galactic plane sensitivity map • in eachbin (b,l) of the map, getNg(g candidates)/ Nhadr • outside sources, Ngisdominated by fake gammas • background B estimated by the « templatemethod » • Ngcompared to B  90% C.L. upperlimit on signal S90 • F90obtainedfrom S90 by • Assumes dN/dEfromccbb (not sensitive to thisassumption) Mc = 500 GeV (from Berge et al 2007) _

  7. Galactic plane flux sensitivity map (HESS) • from HESS galactic survey (2004-2007) • |b| ≤3o, -30o ≤l≤ 60o • map divided into 0.02o x 0.02o bin • smoothed to a 0.1o x 0.1o resolution (HESS) • F.Aharonian et al (HESS)+Bertone,PRD 78 (2008), 072008 Searches for DM subhaloes with Cherenkov telescopes surveys

  8. Dark matter clumps HESS sensitivity • clumps from ViaLacteaII (Diemand, Kuhlen, Madau, 2008) • ~104 resolved halos in MW (M>105Msol) • 103 random realizations (rotate the observer position @8.5 kpc) • 168±44 clumps inside HESS galactic survey Searches for DM subhaloes with Cherenkov telescopes surveys

  9. HESS clump limits • use the HESS Galactic plane sensitivity map • find <sv> so that 2.3 subhalos are seen on average • 90% C.L. limits comparable to Sgr dwarf, Galactic Center(point source) Searches for DM subhaloes with Cherenkov telescopes surveys

  10. assumes x 2 improvement in hadron rejection x 2 gain in angular resolution x 10 gain in effective area  overall increase in sensitivity of ~ 9 expect ~ 300 sources in -30 deg≤ l ≤ 30 deg Expectations for Galactic plane survey Funk,Hinton,Hermann,Digel, arXiV0901.1885 HESS map of the Gal.plane, total exp ~500 hours simulated CTA map, flat exposure ~ 5 hours/field Searches for DM subhaloes with Cherenkov telescopes surveys

  11. Galactic plane sensitivity (CTA) ~400 hours total 10 hours each bin • assume Emin = 50 GeV • 500 GeV WIMP annihilating to bb • x10 gain in effective area, x2 gain in hadron rejection • reaches 10-13 cm-2 s-1 sensitivity, except on new sources Searches for DM subhaloes with Cherenkov telescopes surveys

  12. CTA clump limits (Galactic plane) • 90% C.L. limits improved by an order of mag/ HESS • interesting <sv>s not reached Searches for DM subhaloes with Cherenkov telescopes surveys

  13. CTA clump limits (1/4 sky) • 1/4 survey in ~6 years • assume 5 10-13 cm-2s-1 sensitivity (5 hour/bin) • number of subhalos: 3907±324 • thermal WIMPs region reachable Searches for DM subhaloes with Cherenkov telescopes surveys

  14. Conclusions • 168 DM clumps (estimated from Via Lactea II) expected in field of view of the HESS galactic plane survey • Visibility of clumps depends on <sv>  90% CL limits on <sv> equivalent to HESS galactic center limits. • Limits improved with CTA, however <sv> typical of thermally produced WIMPs not accessible. • Contraints at the level of <sv> ~ 10-26 cm3/s can be obtained by a 6-year survey of ¼ of the sky with CTA. Searches for DM subhaloes with Cherenkov telescopes surveys

  15. Back-up slides Searches for DM subhaloes with Cherenkov telescopes surveys

  16. Dark matter annihilation around IMBH 200 MC realisations NIMBH inside galactic survey HESS sensitivity • « scenario B » of Bertone, Zentner, Silk 2005 • collapse of a primordial cloud of gas ~105 Msol into ~4 104 Msol Intermediate Mass Black Hole • 101±22 IMBH in MW (4.3±2.3 in Hess galactic survey) • very luminous (due to the DM spike around BH) Searches for DM subhaloes with Cherenkov telescopes surveys

  17. HESS IMBH limits (scenario B) • for each mDM, decrease <s v> until NIMBH < 2.3 • F.Aharonian et al (HESS)+Bertone,PRD 78 (2008), 072008 Searches for DM subhaloes with Cherenkov telescopes surveys

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