Dark Matter: what data for incontrovertible evidence? Gianfranco - PowerPoint PPT Presentation

Dark Matter: what data for incontrovertible evidence? Gianfranco Bertone Institut d’Astrophysique de Paris 15 May 2009, RICAP 09, Villa Mondragone (RM) Sabato, 16 maggio 2009

Cosmic e + e - PAMELA, HESS, Fermi, ATIC, PPB-BETS, HEAT, AMS, Caprice... Grasso et al. 2009 Grasso et al. 2009 Sabato, 16 maggio 2009

Interpretation Pulsars DM Annihilation DM Decay Grasso et al. 2009 Strumia et al. 2009 Ibarra et al. 2009 SNRs inhom. SNRs 2 nd ary CR acc. ... + many many other models (200+ citations to PAMELA e+ paper as of May 2009) Piran et al. 2009 Blasi 2009 Sabato, 16 maggio 2009

The Scientific Method I. Observations PAMELA, HESS, Fermi, ATIC, PPB-BETS, HEAT, AMS, Caprice... II. Interpretation Pulsars? SNRs? Dark Matter? Sabato, 16 maggio 2009

The Scientific Method I. Observations PAMELA, HESS, Fermi, ATIC, PPB-BETS, HEAT, AMS, Caprice... II. Interpretation Pulsars? SNRs? Dark Matter? III. Predictions Example: Predictions for other wavelengths, other ‘messengers’; Anisotropy; behaviour in a different energy range IV. TEST If predictions not confirmed, go back to 2 and look for new interpretation, if predictions OK, go back to point 3, devise new predictions. Repeat if possible until all other hypotheses are falsified. NOTE: This process can only Falsify, never Verify a theory! Sabato, 16 maggio 2009

II. DM interpretation Order-zero interpretation: “Vanilla WIMP” Problematic even before moving to point III: requires annihilation cross-section larger than thermal cirelli et al. 2009 To proceed, new hypothesis: large particle physics boost factors, e.g. Sommerfeld enhancement of the annihilation cross-section (or non- standard cosmology, not discussed here). Let’s move to point III. Sabato, 16 maggio 2009

Naive Prediction 1 Associated anti-proton flux Standard WIMP + Somm. disfavored. Back to II: New hypothesis: suppressed hadronic channels! Sabato, 16 maggio 2009

Naive Prediction 2 Associated gamma-ray flux http://www.mpa-garching.mpg.de/aquarius/ Six Milky-Way sized halos at z=0, re-simulated from halos in full cosmological context , to acheive resolutions up to 160 / 224 million particles within r_200. Sabato, 16 maggio 2009

Naive Prediction 2 Associated gamma-ray flux GB, Cirelli, Strumia, Taoso 2009 Standard DM distribution disfavored. New hyp.: Suppressed DM density at the GC. Sabato, 16 maggio 2009

Naive Prediction 3 Associated radio flux Bergstrom, GB, Bringmann, Edsjo, Taoso 2009 Standard B field disfavored. New hyp.: Suppressed DM density at the GC and/or low B field Sabato, 16 maggio 2009

“Standard” DM interpretation Summary of multi-messenger constraints Pato, Pieri, GB 2009 Sabato, 16 maggio 2009

“Standard” DM interpretation yet another (very recent) constraint: CMB! Galli, Iocco, GB, Melchiorri 2009 The interaction of secondary particle from DM annihilation with the thermal gas can 1: ionize it, 2: induce Ly– α excitation of the hydrogen and 3: heat the plasma. The first two modify the evolution of the free electron fraction xe, the third affects the temperature of baryons. Sabato, 16 maggio 2009

The Scientific Method I. Observations PAMELA, HESS, Fermi, ATIC, PPB-BETS, HEAT, AMS, Caprice... II. Interpretation Pulsars? SNRs? Dark Matter? III. Predictions Example: Predictions for other wavelengths, other ‘messengers’; Anisotropy; behaviour in a different energy range IV. TEST If predictions not confirmed, go back to 2 and look for new interpretation, if predictions OK, go back to point 3, devise new predictions. Repeat if possible until all other reasonable hypotheses are falsified. NOTE: This process can only Falsify, never Verify a theory! Sabato, 16 maggio 2009

The Scientific Method I. Observations PAMELA, HESS, Fermi, ATIC, PPB-BETS, HEAT, AMS, Caprice... II. Interpretation Pulsars? SNRs? Dark Matter? III. Predictions Example: Predictions for other wavelengths, other ‘messengers’; Anisotropy; behaviour in a different energy range IV. TEST If predictions not confirmed, go back to 2 and look for new interpretation, if predictions OK, go back to point 3, devise new predictions. Repeat if possible until all other reasonable hypotheses are falsified. NOTE: This process can only Falsify, never Verify a theory! Sabato, 16 maggio 2009

What do we learn? • Is this a serious way of proceeding? Should we panic? • We can adjust the theoretical model ad-libitum, but when do we stop, and how do we claim discovery? • More generally:What Data do we need for Incontrovertible Evidence ? Sabato, 16 maggio 2009

Need of a distinctive feature Sabato, 16 maggio 2009

Need of a distinctive feature Sabato, 16 maggio 2009

What Data for Incontrovertible Evidence? 1) Annihilation Lines (or other unmistakable spectral features) Neutralinos (e.g. Bergstrom and Ullio 1997) KK Dark Matter in UED (Bringmann et al. 2005) Inert Higgs DM (Gustafsson et al. 2007) gravitinos in SUSY with R-parity violation (GB, Buchmueller, Covi & Ibarra 2008) Sabato, 16 maggio 2009

What Data for Incontrovertible Evidence? 1) Annihilation Lines (or other unmistakable spectral features) Neutralinos (e.g. Bergstrom and Ullio 1997) KK Dark Matter in UED (Bringmann et al. 2005) Inert Higgs DM (Gustafsson et al. 2007) gravitinos in SUSY with R-parity violation (GB, Buchmueller, Covi & Ibarra 2008) 2) Multiple Sources with Identical spectra e.g. DM clumps or IMBHs Sabato, 16 maggio 2009

What Data for Incontrovertible Evidence? 1) Annihilation Lines (or other unmistakable spectral features) Neutralinos (e.g. Bergstrom and Ullio 1997) KK Dark Matter in UED (Bringmann et al. 2005) Inert Higgs DM (Gustafsson et al. 2007) gravitinos in SUSY with R-parity violation (GB, Buchmueller, Covi & Ibarra 2008) 2) Multiple Sources with Identical spectra e.g. DM clumps or IMBHs 3) High-Energy Neutrinos from the Sun Icecube, Antares, km3 Fluxes proportional to SCATTERING not annihilation cross section Sabato, 16 maggio 2009

What Data for Incontrovertible Evidence? 1) Annihilation Lines (or other unmistakable spectral features) Neutralinos (e.g. Bergstrom and Ullio 1997) KK Dark Matter in UED (Bringmann et al. 2005) Inert Higgs DM (Gustafsson et al. 2007) gravitinos in SUSY with R-parity violation (GB, Buchmueller, Covi & Ibarra 2008) 2) Multiple Sources with Identical spectra e.g. DM clumps or IMBHs 3) High-Energy Neutrinos from the Sun Icecube, Antares, km3 Fluxes proportional to SCATTERING not annihilation cross section 4) Multi-wavelength / multi-messenger approach Bertone, Sigl & Silk 2001; Aloisio, Blasi & Olinto 2004; Colafrancesco, Profumo & Ullio 2005; Regis & Ullio 2007 Sabato, 16 maggio 2009

What Data for Incontrovertible Evidence? 1) Annihilation Lines (or other unmistakable spectral features) Neutralinos (e.g. Bergstrom and Ullio 1997) KK Dark Matter in UED (Bringmann et al. 2005) Inert Higgs DM (Gustafsson et al. 2007) gravitinos in SUSY with R-parity violation (GB, Buchmueller, Covi & Ibarra 2008) 2) Multiple Sources with Identical spectra e.g. DM clumps or IMBHs 3) High-Energy Neutrinos from the Sun Icecube, Antares, km3 Fluxes proportional to SCATTERING not annihilation cross section 4) Multi-wavelength / multi-messenger approach Bertone, Sigl & Silk 2001; Aloisio, Blasi & Olinto 2004; Colafrancesco, Profumo & Ullio 2005; Regis & Ullio 2007; Pato, Pieri & GB 2009 5) Angular power Spectrum of EG Background Ando & Komatsu 2006, Ando et al. 2007; Siegal-Gaskins 2008; Fornasa, GB et al. 2008 Sabato, 16 maggio 2009

OR... combine indirect searches with complementary strategies Colliders Direct Detection Indirect Detection Sabato, 16 maggio 2009

Concluding thoughts •these are exciting times! •We might have already discovered DM, but we need to devise strategies to make the DM interpretation convincing •For Theorists: keep trying and focus on specific predictions! For phenomenologists: Keep trying to kill theoretical models! •For Incontrovertible evidence we need “smoking-gun” signals. In absence of them, a Multi-Disciplinary approach is the best (maybe only) way to go Sabato, 16 maggio 2009