Search for exotic process with space experiments

Transcription

1 Search for exotic process with space experiments Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata Rencontres de Moriond, Very High Energy Phenomena in the Universe Les Arc, January 2001 Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 1

2 Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 2

3 One year All-Sky Survey Simulation, Eγ > 100 MeV All-sky intensity map based on five years EGRET data. All-sky intensity map from a GLAST one year survey, based on the extrapolation of the number of sources versus sensitivity of EGRET Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 3

4 Probing the era of Galaxy Formation Uncover the nature of Dark Matter Counts / bin Roll- offs in the γ -ray spectra from AGN at large z probe the extra-galactic background light (EBL) over cosmological distances. A dominant factor in EBL models is the era of galaxy formation: AGN roll- offs may help distinguish models of galaxy formation, e. g., Cold Dark Matter vs. Hot Dark Matter-- 5 ev neutrino contributions, etc. See for example Macminn, D., and J. R. Primack, 1995, astro- ph/ (* assumes no intrinsic source cutoff) Energy (GeV) Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 4

5 Dark matter problem (2 S ) Experimentally in spiral galaxies the ratio between the matter density and the Critical density Ω is : Ω lum 0.01 but from rotation curves must exist a galactic dark halo of mass at least: Ω halo from gravitational behavior of the galaxies in clusters the Universal mass density is : Ω halo from structure formation theories: Ω halo 0. 3 but from big bang nucleosinthesis the Barionic matter cannot be more then: Ω B 0. 1 Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 5

6 Massive Compact Halo Objects (MACHOs) Low (sub- solar) mass stars. Standard baryonic composition. Use gravity microlensing to study. Could possibly account for 25% to 50% of Galactic Dark Matter. Neutrinos Candidates for Galactic Dark Matter Small contribution if atmospheric neutrino results are correct, since m ν < 1eV. Large scale galactic structure hard to reconcile with neutrino dominated dark matter Weakly Interacting Massive Particles ( WIMPs) Non- Standard Model particles, ie: supersymmetric neutralinos Heavy (> 10GeV) neutrinos from extended gauge theories. Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 6

7 (1 a ) Flux absorption due to the interaction with the infrared and microwave background γ ray source if the center of mass energy is: Microwave and infrared background γ Ε=ω 1 e + Earth photons interactions produce electron positron pairs γ ϑ Ε=ω 2 e - Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 7

8 (2 a ) Flux absorption due to the interaction with the infrared and microwave background The cross section of the process γγ > e + e - is: where r e is the classical radius of the electron and: ω 1 and ω 1 are respectively the energies of the low and the high energies gamma ray and ϑ is their angle of incidence. γ γ ϑ Ε=ω 1 e + e - Ε=ω 2 Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 8

9 (3 a ) Flux absorption due to the interaction with the infrared and microwave background the ratio between the flux I(L) at a distance L from the source and the initial flux I can be written as: I(L)/I o =exp(-k γ L) where k γ is the absorption coefficient: that contains the cross section and the low energy photon distribution. For the microwave spectrum: γ γ ϑ Ε=ω 1 Ε=ω 2 e + e - Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 9

10 Ratio between surviving flux and initial flux versus photon energies for two different distances due to the sum of the infrared and black-body background (4 a ) Attenuation ( I / I 0 ) Total Absorption ( microwave + infrared) Z=0.03 (low) infrared only 10-3 Z=1 (high) Z=0.03 (high) 10-4 Z=0.03 (high) E(TeV) A.Morselli, INFN/AE-94/22 Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 10

11 Energy density of the extragalactic diffuse background radiation (6 a ) Characteristic absorbed γ ray energy (TeV): E γ (TeV) λ (µm) E 2 n(e) (ev/cm 3 ) Hegra, astro/ph/ Far Infrared Dust Near Infrared Average models Starlight Energy (ev) Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 11

12 Comulative Extragalactic Background light as a function of redshift (6 a ) Cold Dark Matter Model Ω CDM =0.9, Ω b =0.1 early era of galaxy formation ( 1< z f < 3 ) CHDM = Cold + Hot Dark Matter Model Ω CDM =0.6, Ω ν =0.3, Ω b =0.1 late era of galaxy formation ( 0.2 < z f < 1 ) Cold Dark Matter Model CHDM Macminn & Primac astro-ph z Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 12

13 Neutralino WIMPs Assume χ present in the galactic halo χ is its own antiparticle => can annihilate in galactic halo producing gamma-rays, antiprotons, positrons. Antimatter not produced in large quantities through standard processes (secondary production through p + p --> p + X) So, any extra contribution from exotic sources (χ χ annihilation) is an interesting signature ie: χ χ --> p + X Produced from (e. g.) χ χ --> q / g / gauge boson / Higgs boson and subsequent decay and/ or hadronisation. Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 13

14 In the minimal supersymmetric extension of the Standard Model four neutral spin-1/2 Majorana particles are introduced: the partners of the neutral gauge bosons B, W the neutral CP-even higgsinos H 0 1, H 0 2. Diagonalizing the corresponding mass matrix, four mass eigenstates are obtained. The lightest of these, χ, is commonly referred as the neutralino. It is useful to introduce the gaugino fraction Z g defined as: Z g = N N 2 2 and classify the neutralino as higgsino-like when Z g <0.01, mixed when 0.01 < Z g < 0.99 and gaugino like if Z g >0.99. Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 14

15 SuperSymmetric Dark Matter (4 S ) Possible signature: Gamma Ray from Neutralino Annihilation Annihilation at rest: bump around Neutralino mass φ γ Diffuse background 10 GeV 100 GeV A=pseudoscalar χ ± =chargino χ 0 =neutralino H=Higgs boson Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 15

16 (5b S ) Signal rate from Supersymmetry (2) But in more general form we have: where: ψ is the angle between the line of sight and the Galactic center, r(ψ) is the distance along that line of sight I(ψ) is the angular dependence of the gamma-ray flux. The galactic dark matter density distribution can have the form ρ(r) ~ r α with α ~ 1.8 and the predicted photon flux can be 10 4 brighter from certain directions! (the sources can appear nearly point-like) Ι(ψ) R ~ 8.5 kpc ψ Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 16

17 Energy versus time For X and Gamma ray detectors Energy 1 TeV 100 GeV WHIPPLE CAT HEGRA CANGAROO GRANITE MILAGRO ARGO HESS CELESTE, STACEE, Solar Two MAGIC Super Cangaroo VERITAS 10 GeV GLAST 1 GeV EGRET AGILE 100 MeV 10 MeV COMPTEL 1 MeV 100 KeV 10 KeV BATSE OSSE SIGMA RXTE ASCA BeppoSAX INTEGRAL Super AGILE Constellation-X 1 KeV ROSAT Chandra XMM XEUS Year Aldo Morselli Aldo Morselli 10/00 6/9/99 Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 17

18 (5b S ) Signal rate from Supersymmetry (2) But in more general form we have: where: ψ is the angle between the line of sight and the Galactic center, r(ψ) is the distance along that line of sight I(ψ) is the angular dependence of the gamma-ray flux. The galactic dark matter density distribution can have the form ρ(r) ~ r α with α ~ 1.8 and the predicted photon flux can be 10 4 brighter from certain directions! (the sources can appear nearly point-like) Ι(ψ) R ~ 8.5 kpc ψ Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 18

19 GLAST Performance : Energy resolution for lateral photons σ E /E =1.5% θ > 56 0 Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 19

20 Distortion of the secondary antiproton flux induced by a signal from a heavy Higgsino-like neutralino. Background from normal secondary production Signal from very heavy (~ 1 TeV) neutralino annihilations ( astro-ph ) Mass91 data from XXVI ICRC, OG , 1999 Caprice94 data from ApJ, 487, 415, 1997 Particles and photons are sensitive to different neutralinos. Gaugino-like particles are more likely to produce an observable flux of antiprotons whereas Higgsino-like annihilations are more likely to produce an observable gamma-ray signature Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 20

21 Distortion of the secondary positron fraction induced by a signal from a heavy neutralino. M χ =336 GeV K s =11.7 Χ 2 /7=1.53 M χ =2313 GeV K s = Χ 2 /7=1.08 BR(e + e - ) M χ =106 GeV K s =19 Χ 2 /7=2.24 M χ =130 GeV K s =54 Χ 2 /7=1.35 Baltz & Edsjö Phys.Rev. D59 (1999) astro-ph Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 21

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23 Pamela antiproton positron Separating p from e - Magnet Silicon Calorimeter Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 23

24 Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 24

25 Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 25

26 10 GeV e - Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 26

27 10 GeV p Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 27

28 Cosmic Ray Physics with charged particles: - Study of the origin and propagation of cosmic rays using sample of galactic and extragalactic material. - Test of cosmological models - Search for dark matter and supersymmetry Cosmic Ray Physics with photons: - Study of the origin of cosmic rays by looking one by one the sources of cosmic rays - Test of cosmological models - Test of galaxies formation models - Search for dark matter and supersymmetry - Complementary with gravitational waves detectors Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 28

29 Cosmic Ray Physics with charged particles: - Study of the origin and propagation of cosmic rays using sample of galactic and extragalactic material. - Test of cosmological models - Search for dark matter and supersymmetry Cosmic Ray Physics with photons: - Study of the origin of cosmic rays by looking one by one the sources of cosmic rays - Test of cosmological models - Test of galaxies formation models - Search for dark matter and supersymmetry - Complementary with gravitational waves detectors Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 29

30 Summary and 1 st Conclusions Neutralinos are a promising candidate for WIMP dark matter Neutralinos can annihilate in the galactic halo... this could give rise to high energy (> 10GeV) antiproton signature and/or gamma-ray signature. Pamela experiment is designed to measure antiproton spectrum from 80MeV to 190GeV. >3 year mission large event samples Combination of TRD + Si tracker + imaging Si- W calo + TOF (trigger) and anticoincidence can isolate a pure sample of antiprotons. Engineering model currently under construction. Flight model due ~ June Launch: beginning In 2005 GLAST will search for gamma-ray signature Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 30