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Dark Matter Particles: MeV, TeV or heavier? Gianfranco BERTONE

Dark Matter Particles: MeV, TeV or heavier? Gianfranco BERTONE NASA/Fermilab Particle Astrophysics Center bertone@fnal.gov http://home.fnal.gov/~bertone. Theorem If the title of a scientific paper contains a question, then the answer presented in the paper is always “no”. Conjecture

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Dark Matter Particles: MeV, TeV or heavier? Gianfranco BERTONE

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  1. Dark Matter Particles: MeV, TeV or heavier? Gianfranco BERTONE NASA/Fermilab Particle Astrophysics Center bertone@fnal.gov http://home.fnal.gov/~bertone FNAL Colloquium

  2. Theorem If the title of a scientific paper contains a question, then the answer presented in the paper is always “no”. Conjecture If the title of a scientific talk contains a question, then the speaker does NOT know the answer. FNAL Colloquium

  3. Plan of the Talk • Introduction • ~ MeV Dark Matter • INTEGRAL observations @ 511 keV • Astrophysical sources • MeV Dark Matter? • Constraints on MeV DM • ~ TeV Dark Matter • Annihilation radiation from the GC • Dark Matter profiles • The potential of GLAST • Neutrinos from the GC? • Heavier stuff ( > 10 TeV) • ACT results • Interpretation FNAL Colloquium

  4. Open problems in Astrophysics and Theoretical Physics… Astrophysics and Cosmology • Rotation curves of galaxies • Structure formation • CMB • UHE cosmic rays • SN Ia data • Galactic positrons • … Theoretical Physics • Hierarchy problem • Quark/leptons, bosons/fermions • Unification • Quantization of gravity • … Problems FNAL Colloquium

  5. … possible solutions … Astrophysics and Cosmology • Rotation curves of galaxies • Structure formation • CMB • UHE cosmic rays • SN Ia data • Galactic positrons • … • Dark Matter • Dark Energy Theoretical Physics • Hierarchy problem • Quark/leptons, bosons/fermions • Unification • Quantization of gravity • … • Supersymmetry • Extra dimensions • String theory Problems Speculations FNAL Colloquium

  6. …and experimental searches Astrophysics and Cosmology • Rotation curves of galaxies • Structure formation • CMB • UHE cosmic rays • SN Ia data • Galactic positrons • … • Dark Matter • Dark Energy • The Universe Theoretical Physics • Hierarchy problem • Quark/leptons, bosons/fermions • Unification • Quantization of gravity • … • Supersymmetry • Extra dimensions • String theory • LEP, Tevatron, LHC Problems Speculations Experiments FNAL Colloquium

  7. Evidence Evidence for the existence of an unseen, “dark”, component in the energy density of the Universe comes from several independent observations at different length scales: CMB Large Scale Structure Rotation curves of galaxies Galaxy clusters Lensing SN Ia GB, Hooper & Silk, hep-ph/0404175. Bergstrom, hep-ph/0002126. Jungman et al, hep-ph/9506380 FNAL Colloquium

  8. Cosmological Scales 0.133 < Mh2 < 0.137 Cosmic Microwave Background 0.018 < bh2 < 0.024 Big Bang Nucleosynthesis The matter density of the Universe is dominated by non-baryonic Dark Matter. FNAL Colloquium

  9. An Inventory of Matter in the Universe 1% Stars 7% Gas in vir. structures Baryons 7% WH Gas in IGM 85% DARK MATTER Non-baryonic So, what is Dark Matter? FNAL Colloquium

  10. Dark Matter Candidates Kaluza-Klein DM in UED Kaluza-Klein DM in RS Axion Axino Gravitino Photino SM Neutrino Sterile Neutrino Sneutrino Light DM Little Higgs DM Wimpzillas Q-balls Mirror Matter Champs (charged DM) D-matter Cryptons Self-interacting Superweakly interacting Braneworls DM Heavy neutrino NEUTRALINO Messenger States in GMSB Branons Chaplygin Gas Split SUSY Primordial Black Holes L. Roszkowski FNAL Colloquium

  11. Dark Matter Candidates Kaluza-Klein DM inUED Kaluza-Klein DM in RS Axion Axino Gravitino Photino SM Neutrino Sterile Neutrino Sneutrino Light DM Little Higgs DM Wimpzillas Q-balls Mirror Matter Champs (charged DM) D-matter Cryptons Self-interacting Superweakly interacting Braneworls DM Heavy neutrino NEUTRALINO Messenger States in GMSB Branons Chaplygin Gas Split SUSY Primordial Black Holes FNAL Colloquium

  12. New Matter or New Physics? In the past, deviations from Newton’s law found different explanations Uranus, Neptune, etc. Mercury “DARK” PLANETS REFINED LAWS OF GRAVITATION FNAL Colloquium

  13. Plan of the Talk • Introduction • ~ MeV Dark Matter • INTEGRAL observations @ 511 keV • Astrophysical sources • MeV Dark Matter? • Constraints on MeV DM • ~ TeV Dark Matter • Annihilation radiation from the GC • Dark Matter profiles • The potential of GLAST • Neutrinos from the GC? • Heavier stuff ( > 10 TeV) • ACT results • Interpretation FNAL Colloquium

  14. INTEGRAL Satellite INTErnational Gamma-Ray Astrophysics Laboratory • Launched in 2003 • Energy range: 1 keV - 10 MeV • SPI Spectrometer • IBIS Imaging FNAL Colloquium

  15. A view of the Galaxy at 511 keV SPI (aboard INTEGRAL) map of the Galaxy @ 511 keV. • Narrow emission line (few keV) • Size of the emission region FWHM ~ 9 degrees • Roughly corresponds to the size of the bulge • Evidence for positron annihilation through positronium INTEGRAL/SPI FNAL Colloquium

  16. A view of the Galaxy at 511 keV SPI (aboard INTEGRAL) map of the Galaxy @ 511 keV. • Total flux from the bulge ~10-3 photons cm-2 s-1 • Corresponds to 1043 positron annihilations s-1 • Lower limit on the bulge-to-disk ratio is ~0.5 • New INTEGRAL results should be published soon Diameter of the Galactic bulge ~ 2 kpc 10 degrees INTEGRAL/SPI FNAL Colloquium

  17. Positron propagation and annihilation Propagation Positrons below 100 MeV lose energy mainly via ionization losses. Different models have been proposed Random walk in a ~mG B-field D » 1 pc (is ”random walk” accurate?) Propagation in a turbulent magnetic field D » 1 kpc (role of coherent field, uncertainty on the B field, and in particular on the turbulent component, in the bulge) Annihilation Positrons can decay “in flight” or through a bound state called “positronium”. • In flight annihilation produce a continuum • Annihilations through positronium are such that • 25% of the time para-Ps (antiparallel spins for e+ and e-) -> two photons (line at 511keV) • 75% of the time ortho-Ps (parallel spins) -> continuum between 0 and 511keV. Confinement into the bulge, no synchrotron and IC -> low energy e+ Comparison between line and continuum -> annihilation mainly via Ps FNAL Colloquium

  18. Astrophysical sources of positrons: Supernovae Type II • Positrons from decay of radioactive isotopes 56Ni  56Co 56Fe • Only 0.1 M of 56Ni, and positrons have to go through a thick hydrogen envelope • Standard value is 0.07 M , as inferred from SN1987a, but could span at least one order of magnitude (Hamuy 2002) Type Ia • Positrons from decay of radioactive isotopes 56Ni  56Co 56Fe • Possibly 0.6 Mof 56Ni • If ~1053 positrons escape per supernova (Milne 1999), one needs 0.3 SN per century per galaxy, against 0.05 SN/century/galaxy expected. Melissa Weiss, CXC, NASA http://qso.lanl.gov/ FNAL Colloquium

  19. Astrophysical sources of positrons: Hypernovae, GRBs Hypernovae • Explosion (asymmetric) of Wolf-Rayet stars, i.e. C+O core without envelope. Type Ic Supernovae, possibly associated with GRBs (e.g. GRB030329 / SN2003DH). See Casse et al 2004. • .Faster decline of light-curve has been interpreted as evidence for large positron leaking (larger than SN Ia) • Rate in the bulge very uncertain Gamma Ray Bursts • GRBs could be important source of e+. Local rate is »10-6 year-1 galaxy-1 • Possibile detection of GRB remnants at 511keV (Furlanetto and Loeb 2002) • Need of significant leakage of relatively high energy positrons in order toexplain the galactic positron population (Bertone et al. 2004) FNAL Colloquium

  20. Evidence for MeV Dark Matter? Need of MeV DM? Usual dark matter candidates are in the 10 – 103 GeV Difficult to confine them to the bulge, severe constraints from -rays, synchrotron and IC. Need a • LIGHT particle • annihilating ONLY to e-e+ pairs (i.e. below pion threshold) • Suppress the annihilation to photons and neutrinos • Make it invisible to accelerator searches MeV DM Boehm et al. 2003 MeV DM annihilation signal For different values of the density profile power-law index, compared with mean value and 2-sigma range of the INTEGRAL FWHM and normalization. FNAL Colloquium

  21. Theoretical motivation for a light scalar What mediates the interaction? A new heavy particle (heavier than 100 GeV) OR A new gauge boson, lighter than ~GeV e- X X e+ MeV Dark Matter Electrons and Positrons Accelerator searches? • Anomalous single photon experiments: no! cross section for e+ e- ->  ~ 10-6 pb (compared to e.g. e+ e- ->   ~ 10-3 pb) (Boehm and Fayet 2002) Other possibilities • Decay of sterile neutrinos, axinos etc. FNAL Colloquium

  22. An invisible birth for positrons? X e- Internal Bremsstrahlung X e+ MeV Dark Matter Electrons and Positrons FNAL Colloquium

  23. Diffuse gamma-ray emission Strong et al. 1998 FNAL Colloquium

  24. Constraints on MeV Dark Matter Constraints • Masses above 20 MeV correspond to fluxes exceeding the COMPTEL/EGRET constraint (Beacom, Bell & GB 2004) • More precise data would allow an even stronger constraint • Analysis of angular and spectral properties of COMPTEL data in the near future • New INTEGRAL results should soon be available Beacom, Bell & Bertone 2004 FNAL Colloquium

  25. Is there Evidence for Light DM? • There is no evidence, no smoking-gun signal • But astrophysical sources apparently cannot account for Galactic positrons • Although not as well motivated as other candidates, light DM is still a viable solution, also compatible with all collider results. • Window 1--20 MeV OK • Other suggested explanations, sterile neutrinos, axinos, etc. • New results should be published soon, limit on the number of point-like sources. FNAL Colloquium

  26. Plan of the Talk • Introduction • ~ MeV Dark Matter • INTEGRAL observations @ 511 keV • Astrophysical sources • MeV Dark Matter? • Constraints on MeV DM • ~ TeV Dark Matter • Annihilation radiation from the GC • Dark Matter profiles • The potential of GLAST • Neutrinos from the GC? • Heavier stuff ( > 10 TeV) • ACT results • Interpretation FNAL Colloquium

  27. Detection of Dark Matter Colliders Direct Detection Indirect Detection FNAL Colloquium

  28. Basic Idea: A 2 Look for “amplifiers”, i.e. regions where dark matter accumulates (galactic center, halo clumps, sun, earth…) Particle Physics Astrophysics FNAL Colloquium

  29. Dark Matter Distribution: Theoretical Understanding Early analytic calculations: scale-free nature of gravitation  power-laws (Gunn and Gott 1972, Fillmore and Goldreich 1984 etc.) Real DM from complex history of mergers  need of Numerical Simulations. Profile in the innermost regions is CRUCIAL for indirect detection. FNAL Colloquium

  30. From the first “numerical simulation”, Holmberg 1941… FNAL Colloquium

  31. First numerical simulation, Holmberg 1941 FNAL Colloquium

  32. …to supercomputers, Zbox 2005 zBox Resources Number of CPUs: 288 Number of CPUs per Node: 2 CPU type: AMD MP2200+ Memory: 144 GB Disk: 11.5 TB, 80 GB per Node Frontend Resources zBox Host CPUs: 2 Intel 2.6 GHz FNAL Colloquium

  33. Dark Matter Distribution: Theoretical Understanding Early analytic calculations: scale-free nature of gravitation power-laws (Gunn and Gott 1972, Fillmore and Goldreich 1984 etc.) Real DM from complex history of mergersneed of Numerical Simulations. r -1 r -3 Profile in the innermost regions is CRUCIAL for indirect detection. FNAL Colloquium

  34. Dark Matter Distribution: Recent developments Profiles probably become shallower than NFW in the innermost regions Logarithmic slope continuously decreasing Extrapolation of power-laws probably leads to an overestimate of the central density Different groups obtained similar results. See Navarro et al. 2003 (figure), Reed et al. 2003 Navarroet al. 2003 NFW profile can be considered as an “upper limit”. FNAL Colloquium

  35. Evidence for a Supermassive Black Hole at the Galactic Centre M= 3.6 x 106Solar Masses Genzel et al. 2003 FNAL Colloquium

  36. The inner parsec What happens in the inner parsec? Profiles are modified due to • The presence of the SMBH (spike) • Scattering off the stellar cusp (heating of DM, scatter into the SMH) • Annihilations Combined evolution of Dark and baryonic matter GB and Merritt 2005 FNAL Colloquium

  37. Spikes – combined evolution of DM and baryons GB and Merritt, 2005 FNAL Colloquium

  38. Annihilation Radiation Neutrinos • direct production • decay of heavy quarks • hadronization followed by decay of charged pions, X Photons Direct production Hadronization then Decay of neutral pions X Direct production Hadronization and decay e+e- pairs Direct production Hadronization then Decay of charged pions Initial State (X=  or B(1)) Relevant final states FNAL Colloquium

  39. Annihilations E. Nezri et al, 2001 To compute fluxes, one has to go through the details of annihilation. Annihilation cross sections for neutralinos can be computed with the DarkSUSY code. Other codes are on the market, microMEGA among the most complete (and PUBLIC !) Servant & Tait, 2002 Servant & Tait recently worked out annihilation cross sections for B(1) particles, which, in the non-relativistic limit, only depend on the mass of the particle. FNAL Colloquium

  40. -ray flux from the GC Predictions for KK dark matter and neutralinos in the case of a NFW profile without central spike. Fluxes are always below the EGRET normalisation, but within the reach of several future experiments. Possibility of constraining B(1) mass. Importance of the dark matter density profile. GB, Servant & Sigl 2003 Without SPIKE FNAL Colloquium

  41. Recent Developments: Air Cherenkov Telescopes CANGAROO II Australia Whipple (Veritas) in Arizona HESS in Namibia FNAL Colloquium

  42. Recent Developments: Air Cherenkov Telescopes CANGAROO II Australia Whipple (Veritas) in Arizona Has detected a TeV source at the GC Has detected a TeV source at the GC HESS in Namibia Has detected a TeV source at the GC FNAL Colloquium

  43. Air Cherenkov Telescopes http://www.mpi-hd.mpg.de FNAL Colloquium

  44. Multi – TeV image of the Galactic center HESS coll. HESS coll. HESS coll. (on Chandra image) FNAL Colloquium

  45. The TeV source at the GC HESS Position of Sgr A* Adapted from Hooper et al. 2004 FNAL Colloquium

  46. The TeV source at the GC: spectrum Aharonian et al. 2004 FNAL Colloquium

  47. The TeV source at the GC: spectrum GLAST Aharonian et al. 2004 FNAL Colloquium

  48. Implications of HESS results • Usual Dark Matter candidates are not that massive (need >12 TeV !!!!) Any ideas? • Astrophysical sources are probably more likely, in particular • The Central Supermassive Black Hole, (possible because of low luminosity) through synchrotron and curvature radiation of protons, or acceleration in strong shocks or electric fields induced by rotation. Associated TeV neutrino flux? Aharonian and Neronov 2004, Atoyan and Dermer 2004 • The Supernova Remnant Sgr A East, through pion production in a very dense, strongly magnetized environment (Fatuzzo and Melia 2003) • However, the observational situation is unclear, GLAST will cover the gap between EGRET and ACTs. • Dark Matter annihilations are NOT ruled out by the ACTs observations. FNAL Colloquium

  49. First TeV image of an extended source!! SNR RX J1713.7 -3946 Aharonian et al. 2004 (Nature, only two months ago!) FNAL Colloquium

  50. CONCLUSIONS Astrophysics provides useful constraints on physics beyond the SM Indirect detection of DM • MeV Dark Matter (available range left 1 < M (MeV) < 20), Galactic positrons still a puzzle • Prospects of indirect detection with GLAST • ACTs and the gamma-ray source at the Galactic center • Alternative strategies: synchrotron, neutrinos Future developments Angular and spectral features of COMPTEL data will allow to reduce the available range for MeV Dark Matter A better understanding of the DM profiles, especially in the innermost regions of the Galaxy, keeping into account SMBH, stars, annihil. The new TeV results on the galactic center are exciting, possibility to test astrophysical and particle physics scenarios FNAL Colloquium

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