sea rch for exotic process with space experimentspeople.roma2.infn.it/~morselli/moriond01.pdf ·...

Aldo Morselli INFN, Sezione di Roma 2 & Università di Roma Tor Vergata 1

Search for exotic process withspace experiments

Aldo MorselliINFN, Sezione di Roma 2 &

Università di Roma Tor Vergata

Rencontres de Moriond, Very High Energy Phenomena in the Universe

Les Arc, 20-27 January 2001


One year All-Sky Survey Simulation,

All-sky intensity map based on five years EGRET data.

Eγ > 100 MeV

All-sky intensity map from a GLAST one year survey, based on the extrapolation of the number of sourcesversus sensitivity of EGRET


Probing the era of Galaxy FormationUncover the nature of Dark Matter

Roll- offs in the γ -ray spectra from AGN at large z probe theextra-galactic background light(EBL) over cosmological distances. A dominant factor in EBL modelsis the era of galaxy formation:AGN roll- offs may help distinguishmodels of galaxy formation, e. g.,Cold Dark Matter vs. Hot DarkMatter-- 5 eV neutrinocontributions, etc.

See for exampleMacminn, D., and J. R. Primack,1995, astro- ph/ 9504032.

Coun

ts / b

in

Energy (GeV)(* assumes no intrinsic source cutoff)


Experimentally in spiral galaxies the ratio between the matter density and theCritical density Ω is :

Ω lum ≤ 0.01but from rotation curves must exist a galactic dark halo of mass at least:

Ω halo ≥ 0.03 ÷ 0.1

from gravitational behavior of the galaxies in clusters the

Universal mass density is :Ω halo ≅ 0.1 ÷ 0.3

from structure formation theories:Ω halo ≥ 0. 3

but from big bang nucleosinthesis the Barionic matter cannot be more then:Ω B ≤ 0. 1

Dark matter problem(2S)


• 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• Small contribution if atmospheric neutrino results are correct, since mν< 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.

Candidates for Galactic Dark Matter


Flux absorption due to the interaction with the infrared and microwave background

γ ray source

Microwave and infrared background

Earth

Ε=ω2

γ

γ

e+

e-

Ε=ω1

ϑ

if the center of mass energy is:

photons interactions produce electron positron pairs

(1a)



Ε=ω1

γ

γ

e+

e-

Ε=ω2

ϑ ω1 and ω1 are respectively the energies of the low and the high energies gamma ray and ϑ is their angle of incidence.

The cross section of the process γγ −> e+e- is:

where re is the classical radius of the electron and:

(2a)



γ

γ

e+

e-

Ε=ω1

Ε=ω2

ϑ

the ratio between the flux I(L) at a distance L from the sourceand the initial flux I can be written as:

I(L)/Io=exp(-kγ L)where kγ is the absorption coefficient:

that contains the cross section and the low energy photon distribution.For the microwave spectrum:

(3a)


10-4

10-3

10-2

10-1

100

10-2

100

102

104

106

108

Total Absorption ( microwave + infrared) A

tten

uat

ion (

I /

I 0 )

E(TeV)

Z=1 (high)

Z=0.03 (high)

Z=0.03 (low)

infrared only

Z=0.03 (high)

A.Morselli , INFN/AE-94/22

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

(4a)


Energy density of the extragalactic diffuse background radiation(6a)

Hegra

Far Infrared Near Infrared

Average models

102

12.5 1.25 0.125125125012500 λ (µm)Characteristic absorbed γ ray energy (TeV): 110 0.1103 Eγ (TeV)

Dust Starlight

, astro/ph/9802308

Energy (ev)

E2 n(E

) (ev

/cm

3 )


Comulative Extragalactic Background light as a function of redshift(6a)

z

Cold Dark Matter Model

CHDMCHDM = Cold + Hot Dark Matter ModelΩCDM=0.6 , Ων=0.3 , Ωb=0.1late era of galaxy formation ( 0.2 < zf < 1 )

Macminn & Primac astro-ph 950432

Cold Dark Matter ModelΩCDM=0.9 , Ωb=0.1early era of galaxy formation ( 1< zf < 3 )


Assume χ present in the galactic halo• χ is its own antiparticle => can annihilate in galactic haloproducing 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 aninteresting signature• ie: χ χ --> p + X• Produced from (e. g.) χ χ --> q / g / gauge boson / Higgs boson andsubsequent decay and/ or hadronisation.

Neutralino WIMPs


In the minimal supersymmetric extension of the Standard Modelfour neutral spin-1/2 Majorana particles are introduced:• the partners of the neutral gauge bosons B, W• the neutral CP-even higgsinos H0

1, H02.

Diagonalizing the corresponding mass matrix, four mass eigenstates areobtained. The lightest of these, χ , is commonly referred as the neutralino.

It is useful to introduce the gaugino fraction Zg defined as:

Zg= |N1|2 + |N2|2

and classify the neutralino as higgsino-like when Zg <0.01, mixedwhen 0.01 < Zg < 0.99 and gaugino like if Zg >0.99.


SuperSymmetric Dark MatterPossible signature:Gamma Ray from Neutralino Annihilation

A=pseudoscalarχ±=charginoχ0 =neutralinoH=Higgs boson

Annihilation at rest:bump around Neutralino mass

10 GeV 100 GeV

φγDiffuse background

(4S)


Signal rate from Supersymmetry (2)

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 formρ(r) ~ r−α with α ~ 1.8 and the predicted photon flux can be104 brighter from certain directions!(the sources can appear nearly point-like)

(5bS)

But in more general form we have:

ψ

Ι(ψ)

R ~ 8.5 kpc


Energy versus time For X and Gamma ray detectors

1992 1994 1996 1998 2000 2002 2004 2006 2008

TIMELINE

En

erg

y

Year

10 GeV

100 GeV

1 TeV

100 MeV

10 MeV

GRANITE

VERITAS

GLAST

EGRET

WHIPPLE

INTEGRAL

CAT

HEGRA

CANGAROOHESS

Super Cangaroo

1 GeV

1 MeV

100 KeV

10 KeV

1 KeV

BeppoSAXRXTE

BATSE

OSSE

Chandra

MILAGRO

AGILESuper

XMM

SIGMA

Constellation-X

CELESTE,STACEE,Solar Two

ARGO MAGIC

AGILE

Aldo Morselli 6/9/99 http://www.roma2.infn.it/infn/agile/

XEUS

COMPTEL

ASCA

ROSAT

Aldo Morselli 10/00 http://www.roma2.infn.it/infn/agile/


Signal rate from Supersymmetry (2)

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 formρ(r) ~ r−α with α ~ 1.8 and the predicted photon flux can be104 brighter from certain directions!(the sources can appear nearly point-like)

(5bS)

But in more general form we have:

ψ

Ι(ψ)

R ~ 8.5 kpc


GLAST Performance : Energy resolution for lateral photons

σE/E =1.5%θ > 560


( astro-ph 9904086)

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

Particles and photons are sensitive todifferent neutralinos. Gaugino-like particles are more likely to produce an observable flux of antiprotonswhereas Higgsino-like annihilations aremore likely to produce an observable gamma-ray signature

Mass91 data from XXVI ICRC, OG.1.1.21 , 1999

Caprice94 data from ApJ , 487, 415, 1997

•


Baltz & EdsjöPhys.Rev. D59 (1999)astro-ph 9808243

Distortion of the secondary positron fraction induced by a signal from a heavy neutralino.

Mχ=336 GeVKs=11.7Χ2/7=1.53

Mχ=2313 GeVKs=1 104

Χ2/7=1.08

Mχ=130 GeVKs=54Χ2/7=1.35

BR(e+e-)Mχ=106 GeVKs=19Χ2/7=2.24


antiproton positron

Pamela

SiliconCalorimeter

Magnet

Separating p from e-


10 GeV e-


10 GeV p


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 galaxies formation models


- Complementary with gravitational waves detectors


Cosmic Ray Physics with charged particles:- Study of the origin and propagation of cosmic rays using sample of galactic and extragalactic material.



Cosmic Ray Physics with photons:- Study of the origin of cosmic rays by looking one by one the sources of cosmic rays


- Test of galaxies formation models


- Complementary with gravitational waves detectors


• 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 signatureand/or gamma-ray signature.Pamela experiment is designed to measure antiproton spectrum from80MeV 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 2002.• Launch: beginning 2003.

In 2005 GLAST will search for gamma-ray signature

Summary and 1st Conclusions

sea rch for exotic process with space experimentspeople.roma2.infn.it/~morselli/moriond01.pdf ·...

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