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Dark Matter: what data for incontrovertible evidence? Gianfranco Bertone Institut dAstrophysique 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,

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SLIDE 1

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

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SLIDE 2

Cosmic e+e-

PAMELA, HESS, Fermi, ATIC, PPB-BETS, HEAT, AMS, Caprice...

Grasso et al. 2009 Grasso et al. 2009

Sabato, 16 maggio 2009

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SLIDE 3

Interpretation

Pulsars DM Annihilation DM Decay SNRs inhom. SNRs 2ndary CR acc.

Blasi 2009 Piran et al. 2009 Grasso et al. 2009 Strumia et al. 2009 Ibarra et al. 2009

... + many many other models (200+ citations to PAMELA e+ paper as

  • f May 2009)

Sabato, 16 maggio 2009

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The Scientific Method

  • I. Observations

PAMELA, HESS, Fermi, ATIC, PPB-BETS, HEAT, AMS, Caprice...

  • II. Interpretation

Pulsars? SNRs? Dark Matter?

Sabato, 16 maggio 2009

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SLIDE 5

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

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SLIDE 6
  • II. DM interpretation

Order-zero interpretation: “Vanilla WIMP” Problematic even before moving to point III: requires annihilation cross-section larger than thermal 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.

cirelli et al. 2009

Sabato, 16 maggio 2009

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Naive Prediction 1

Associated anti-proton flux Standard WIMP + Somm. disfavored. Back to II: New hypothesis: suppressed hadronic channels!

Sabato, 16 maggio 2009

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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

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SLIDE 9

Naive Prediction 2

Associated gamma-ray flux Standard DM distribution disfavored. New hyp.: Suppressed DM density at the GC.

GB, Cirelli, Strumia, Taoso 2009

Sabato, 16 maggio 2009

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SLIDE 10

Associated radio flux Standard B field disfavored. New hyp.: Suppressed DM density at the GC and/or low B field

Naive Prediction 3

Bergstrom, GB, Bringmann, Edsjo, Taoso 2009

Sabato, 16 maggio 2009

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SLIDE 11

“Standard” DM interpretation

Summary of multi-messenger constraints

Pato, Pieri, GB 2009

Sabato, 16 maggio 2009

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SLIDE 12

“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

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SLIDE 13

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

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SLIDE 14

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

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SLIDE 15

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

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SLIDE 16

Need of a distinctive feature

Sabato, 16 maggio 2009

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SLIDE 17

Need of a distinctive feature

Sabato, 16 maggio 2009

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SLIDE 18

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

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SLIDE 19

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

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SLIDE 20

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

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SLIDE 21

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

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SLIDE 22

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

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SLIDE 23

OR... combine indirect searches with complementary strategies

Indirect Detection Direct Detection Colliders

Sabato, 16 maggio 2009

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SLIDE 24

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