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暗暗暗暗暗暗暗暗暗暗暗暗暗暗 暗暗暗暗暗暗暗暗暗暗暗暗暗暗 暗暗暗暗暗暗CANGAROO CANGAROO 暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗暗 暗暗 暗 暗暗 暗 暗暗 暗暗 20031211() 暗暗 暗暗 暗 暗暗 暗 暗暗 暗暗 20031211() - - 暗暗 暗暗 12() 暗暗 暗暗 12() 暗暗 暗暗暗暗 暗暗暗暗暗暗暗暗 暗暗暗暗暗 暗暗 暗暗暗暗 暗暗暗暗暗暗暗暗 暗暗暗暗暗 3F 3F 暗暗暗暗 暗暗暗暗 暗暗暗暗 ( 暗暗暗暗暗暗暗暗暗暗

暗黒物質対消滅起源のガンマ線 研究会「 CANGAROO 望遠鏡によるガンマ線天文学の新展 開」 日時: 2003年12月11日(木) - 12日(金)

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Text of 暗黒物質対消滅起源のガンマ線 研究会「 CANGAROO...

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  • CANGAROO - 3F (
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  • 1, Introduction Fit to the WMAP, CBI, ACBAR, 2dFGRS and Lyman forest data 2dFGRS v.s. N-body simulation for Large-scale structure formation What is this dark matter? Evidence of cold dark matter
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  • Candidate of dark matter MACHO (almost excluded) Microlensing Microlensing Wide binaries Wide binaries Neutrino (Not cold) It might be hot dark matter, thus It might be hot dark matter, thus Unknown stable particle Relics in the early hot universe. Relics in the early hot universe. WIMP (Weakly interacting massive particle) (Cold) WIMP (Weakly interacting massive particle) (Cold) SUSY particle, Kaluza-Klein particle, Wimpzilla,,, SUSY particle, Kaluza-Klein particle, Wimpzilla,,, Axion (Cold) Axion (Cold) (Chaname et al)
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  • SUSY dark matter Solves hierarchy problem SUSY GUTs Light Higgs boson Lightest SUSY particle(LSP) is stable due to R parity. stable due to R parity. SM particles; even, SUSY particles; odd SM particles; even, SUSY particles; odd Dark Matter Dark Matter
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  • Nature of LSP It depends on the SUSY breaking mechanism Neutralino ; Neutralino ; Bino -like or Higgsino -like in supergravity Bino -like or Higgsino -like in supergravity Wino -like in the anomaly mediation Wino -like in the anomaly mediation Gravitino in the gauge mediation Gravitino in the gauge mediation Direct search for DM the nucleus elastic scattering Dirac neutrino (sneutrino) mass > 100TEV Dirac neutrino (sneutrino) mass > 100TEV Dark matter should be Majorana fermion or real scalar Dark matter should be Majorana fermion or real scalar if it has weak charge. if it has weak charge.
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  • DM genesis Thermal abundance is blocked when is blocked when Smaller may mean larger annihilation rate. Notice co-annihilation may enhances cross section when SUSY particles masses are degenerate. (Nath et al)
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  • Non-thermal production DM is produced after by non-thermal process. DM is produced after by non-thermal process. (for example, ) (for example, ) In this case, the larger annihilation rate, such as in Higgsino-like or Wino-like case, is favored.
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  • Detection of DM Direct detection by elastic scattering with nucleus. DAMA, EDELWEISS, CDMS, Zeplin, DAMA, EDELWEISS, CDMS, Zeplin, Indirect detection of neutrinos, antiproton, positron, and gamma ray from DM annihilation in our Galaxy, Sun, or Eearh. Collider experiment LHC starts on 07. LHC starts on 07. It determine mass and properties of the DM candidate. It determine mass and properties of the DM candidate.
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  • 2, Dark matter distribution N-body simulation provides universal cuspy profile for the halo DM density distributon (Navarro, Frenk & White, 96,97). Navarro, Frenk &White Moore
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  • High resolution N body simulation Large N and small time stepsize are required. Time evolution Recent simulation observed deviation from the universal profile for (Figures;Fukushige and Makino)
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  • Cusp/Core problem Rotation curve measure ment of Low Surface- brightness Galaxies by HI and Halpha. Data prefer soft cores. Data prefer soft cores. Early suspicion on observation; Early suspicion on observation; beaming, pointing error, beaming, pointing error, small sample, inconsistency small sample, inconsistency among observations, etc. among observations, etc. de Blok(2003): These problems de Blok(2003): These problems no more exit.
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  • Measurement of gravitational lense constrains DM profile for clusters. Sand et al show Sand et al show Objection :Ellipticity (Dalal et al) Objection :Ellipticity (Dalal et al) A little good news. for large radius is favored. for large radius is favored. (CL0024+11654, Kneib et al)
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  • Our galaxy Our galaxy is High surface-brightness galaxy. (Baryon rich, Bar, BH ) (Baryon rich, Bar, BH ) It is difficult to say something, especially DM profile around the galactic center. It is difficult to say something, especially DM profile around the galactic center. http://www.astronomynotes.com/ismnotes/rotcurv2-big.gif
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  • 3, Gamma ray from DM annihilation in Galactic center Gamma ray from DM annihilation line spectrum: line spectrum: continuum spectrum: continuum spectrum: Merit and Demerit Merit: Characteristic spectrum, e.g. line. Merit: Characteristic spectrum, e.g. line. Sensitive to heavier DM Sensitive to heavier DM Demerit: Cross section depends on DM proparties. Demerit: Cross section depends on DM proparties. Sensitive to DM halo profile. Sensitive to DM halo profile.
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  • Gamma ray flux
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  • Galactic Halo profile Dependence on DM profile is huge. In the following, I take the moderate value, that is
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  • DM annihilation cross section Annihilation cross section to fermions is suppressed by the fermion mass due to the S wave annihilation. Sizable cross section to continum gammais expected when Sizable cross section to continum gammais expected when Cross section depends on propaties of the DM. Case 1:Bino-like DM. Case 1:Bino-like DM. Interaction is very weak. Interaction is very weak. MSUGRA + thermal production favor this. MSUGRA + thermal production favor this. Case 2: Higgsino or Wino DM. Case 2: Higgsino or Wino DM. These have SU(2) weak charge. These have SU(2) weak charge.
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  • Bino-like DM Line spectrum. Sensitive to slepton mass. Sensitive to slepton mass. Continuum spectrum MSUGRA simulation by MSUGRA simulation by Feng et al. Feng et al.
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  • Higgsino or Wino DM They have SU(2) weak charge and acompany with SU(2) partner, those are chargino, When they are heavier than W boson mass, the masses are degenerate. Annihiration cross section to 2 gammas is independent of the DM mass at the leading order. This means that line gamma search is sensitive to This means that line gamma search is sensitive to heavier DM. heavier DM. However, this behavior is strange since However, this behavior is strange since
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  • Non-relativistic effects DM is highly non-relativistic. Thus, the cross section is sensitive to existence of bound state under Yukawa potential induced by W exchange. Wino-like Higgsino-like Leading order cal. Bound state W-exchanged Yukawa potential Zero energy resonance enhances the cross section.
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  • Line spectrum ( ). Wino-likeHiggsino-like
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  • Continuum spectrum ( ) Wino-likeHiggsino-like Photon energy (GeV) There are already some regions constrained by the EGRET. The shaded regions correspond to S> BG.
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  • EGLET Gamma ray spectrum from Galactic center observed by EGLET is not well fit to the standard explanation of diffused gamma, It might come from DM annihilation. (Cesarini et al)
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  • 4, Summary After WMAP measurement, DM search is very important subject. Gamma from DM annihilation is sensitive to relatively heavier DM, and it has different dependence from other DM searches. Will gamma from DM annihilation at Galactic center be observed or not ? Or, can we discriminate particle physics models or astronomical models? At present, it is hard to answer them, because gamma ray signal depend on detail of both models. If DM candidate is discovered at new collider (LHC?) or DM-like gamma ray is observed, DM astronomy will be started. If DM candidate is discovered at new collider (LHC?) or DM-like gamma ray is observed, DM astronomy will be started.