Challenges in astrophysics of cr knee rays
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Challenges in Astrophysics of CR (knee--) & γ -rays. Igor V. Moskalenko (Stanford U.). Topics covered: Intro to the relevant physics Modeling of the CR propagation and diffuse emission Perspectives: Pamela, GLAST and other near future missions. CR Interactions in the Interstellar Medium.

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Challenges in astrophysics of cr knee rays

Challenges in Astrophysicsof CR (knee--) & γ-rays

Igor V. Moskalenko (Stanford U.)

  • Topics covered:

  • Intro to the relevant physics

  • Modeling of the CR propagation and diffuse emission

  • Perspectives: Pamela, GLAST and other near future missions


Cr interactions in the interstellar medium

CR Interactions in the Interstellar Medium

SNR RX J1713-3946

42 sigma (2003+2004 data)

B

HESS Preliminary

PSF

π

0

e

e

e

π

π

gas

gas

_

+

+

+

+

+

-

-

-

-

-

P

ISM

X,γ

synchrotron

Chandra

IC

ISRF

P

He

CNO

diffusion

energy losses

reacceleration

convection

etc.

bremss

GLAST

p

Flux

LiBeB

He

CNO

20 GeV/n

BESS

  • CR species:

  • Only 1 location

  • modulation

PAMELA

ACE

AMS

helio-modulation


Elemental abundances cr vs solar system

Volatility

Elemental Abundances: CR vs. Solar System

CR abundances: ACE

O

Si

Na

Fe

S

CNO

Al

Cl

CrMn

LiBeB

F

ScTiV

Solar system abundances

Long propagation history…


Nuclear component in cr what we can learn

Dark

Matter

(p,đ,e+,γ)

-

Nuclear component in CR: What we can learn?

Nucleo-

synthesis:

supernovae,

early universe,

Big Bang…

Stable secondaries:

Li, Be, B, Sc, Ti, V

Propagation parameters:

Diffusion coeff., halo size, Alfvén speed, convection velosity…

Radio (t1/2~1 Myr):

10Be, 26Al, 36Cl, 54Mn

K-capture:37Ar,49V, 51Cr, 55Fe, 57Co

Energy markers:

Reacceleration, solar modulation

Diffuse γ-rays

Galactic,

extragalactic:

blazars, relic

neutralino

Short t1/2radio 14C & heavy Z>30

Local medium: Local Bubble

Solar

modulation

Heavy Z>30:

Cu, Zn, Ga, Ge, Rb

Material & acceleration sites, nucleosynthesis (r-vs. s-processes)


Diffuse galactic gamma ray emission

Diffuse Galactic Gamma-ray Emission

~80% of total Milky Way luminosity at HE !!!

Tracer of CR (p, e−) interactions in the ISM (π0,IC,bremss):

  • Study of CR species in distant locations (spectra & intensities)

    • CR acceleration (SNRs, pulsars etc.) and propagation

  • Emission from local clouds → local CR spectra

    • CR variations, Solar modulation

  • May contain signatures of exotic physics (dark matter etc.)

    • Cosmology, SUSY, hints for accelerator experiments

  • Background for point sources (positions, low latitude sources…)

  • Besides:

  • “Diffuse” emission from other normal galaxies (M31, LMC, SMC)

    • Cosmic rays in other galaxies !

  • Foreground in studies of the extragalactic diffuse emission

  • Extragalactic diffuse emission (blazars ?) may contain signatures of exotic physics (dark matter, BH evaporation etc.)

Calculation requires knowledge of CR (p,e) spectra in the entire Galaxy


Transport equations 90 no of cr species

Transport Equations ~90 (no. of CR species)

ψ(r,p,t) – density per total momentum

sources (SNR, nuclear reactions…)

diffusion

convection (Galactic wind)

diffusive reacceleration (diffusion in the momentum space)

E-loss

radioactive decay

fragmentation

+ boundary conditions


Cr propagation milky way galaxy

Halo

Gas, sources

CR Propagation: Milky Way Galaxy

1kpc ~ 3x1018cm

Optical image: Cheng et al. 1992, Brinkman et al. 1993

Radio contours: Condon et al. 1998 AJ 115, 1693

100 pc

NGC891

40 kpc

0.1-0.01/ccm

1-100/ccm

Sun

4-12 kpc

Intergalactic space

R Band image of NGC891

1.4 GHz continuum (NVSS), 1,2,…64 mJy/ beam

“Flat halo” model (Ginzburg & Ptuskin 1976)


A model of cr propagation in the galaxy

A Model of CR Propagation in the Galaxy

  • Gas distribution (energy losses, π0, brems)

  • Interstellar radiation field (IC, e± energy losses)

  • Nuclear & particle production cross sections

  • Gamma-ray production: brems, IC, π0

  • Energy losses: ionization, Coulomb, brems, IC, synch

  • Solve transport equations for all CR species

  • Fix propagation parameters

  • “Precise” Astrophysics


Challenges in astrophysics of cr knee rays

Wherever you look, the GeV -ray excess is there !

EGRET data

4a-f


Reacceleration model vs plain diffusion

Antiproton flux

B/C ratio

B/C ratio

Antiproton flux

Reacceleration Model vs. Plain Diffusion

Plain Diffusion

(Dxx~β-3R0.6)

Diffusive

Reacceleration


Positron excess

Positron Excess ?

HEAT (Beatty et al. 2004)

  • Are all the excesses connected somehow ?

  • A signature of a new physics (DM) ?

    Caveats:

  • Systematic errors ?

  • A local source of primary positrons ?

  • Large E-losses -> local spectrum…

e+/e

e+/e

E > 6 GeV

GALPROP

HEAT 2000

HEAT 1994-95

HEAT combined

GALPROP

10

1

1

10

E, GeV

E, GeV

Q: Are all the excesses connected?

A: “Yes” and “No”

Systematic errors of different detectors

Same progenitor (CR p or DM) for pbars, e+’s, γ’s


Cr source distribution

CR Source Distribution

Lorimer 2004

Pulsars

SNR source

CR after

propagation

diffuse γ-ray

distribution

The CR source (SNRs, pulsars) distribution is too narrow to match the CR distribution in the Galaxy assuming XCO=N(H2)/WCO=const (CO is a tracer of H2)


Challenges in astrophysics of cr knee rays

Positron Annihilation Line

All sky view of 511 keV emission

Knödlseder et al 2005

INTEGRAL-SPI

Life and death of e+

Injection into

the ISM

Energy loss

Positronium

In flight

Thermalisation

Radiative

Capture

Charge

Exchange

Direct annihilation

with free electrons

Direct annihilation

with bound electrons

Grains

Positronium

3g

2g

2g

2g

W.Gillard


Hypotheses

Hypotheses…

Provide good agreement with all

data (diffuse gammas, pbars, e+)

  • CR intensity variations

  • Dark Matter signals

    Other possibilities:

    Harder CR spectrum (protons, electrons) – deviates limits from pbars, gamma-ray profiles

    Influence of the Local Bubble (local component) – helps with pbars, but doesn’t help with diffuse gammas


Diffuse emission models

Diffuse emission models

Cosmic Ray

Spectral Variations

EGRET “GeV Excess”

Dark Matter

from Hunter et al. ApJ (1997)

from Strong et al. ApJ (2004)

from de Boer et al. A&A (2005)

  • There are two possible BUT fundamentally different explanations of the excess, in terms of exotic and traditional physics:

    • Dark Matter

    • CR spectral variations

  • Both have their pros & cons.

0.5-1 GeV

>0.5 GeV


Cr variations in space time

SNR number density

R, kpc

CR Variations in Space & Time

More frequent SN

in the spiral arms

Historical variations of CR intensity: ~40kyr (10Be in South Polar ice), ~2.8Myr (60Fe in deep sea FeMn crust)

Konstantinov et al. 1990

Electron/positron

energy losses

Different “collecting” areas A vs. p (σ~30 mb)

(different sources ?)


Electron fluctuations snr stochastic events

Electron Fluctuations/SNR stochastic events

GeV electrons

100 TeV electrons

GALPROP/Credit S.Swordy

Electron energy loss timescale:

1 TeV: ~300 kyr

100 TeV: ~3 kyr

Energy losses

Bremsstrahlung

E(dE/dt)-1,yr

Ionization

IC, synchrotron

Coulomb

107 yr

1 GeV

1 TeV

106 yr

Ekin, GeV


Gev excess optimized reaccleration model

GeV excess: Optimized/Reaccleration model

antiprotons

Uses all sky and antiprotons & gammas

to fix the nucleon and electron spectra

  • Uses antiprotons to fix

    the intensity of CR nucleons @ HE

  • Uses gammas to adjust

    • the nucleon spectrum at LE

    • the intensity of the CR electrons

      (uses also synchrotron index)

  • Uses EGRET data up to 100 GeV

Ek, GeV

protons

electrons

x4

x1.8

Ek, GeV

Ek, GeV


Secondary e are seen in rays

Secondary e± are seen in γ-rays !

Lots of new effects !

electrons

Heliosphere: e+/e~0.2

sec.

IC

positrons

brems

Improves an agreement at LE


Diffuse gammas at different sky regions

Diffuse Gammas at Different Sky Regions

Hunter et al. region:

l=300°-60°,|b|<10°

Outer Galaxy:

l=90°-270°,|b|<10°

Inner Galaxy:

l=330°-30°,|b|<5°

corrected

Intermediate latitudes:

l=0°-360°,10°<|b|<20°

l=40°-100°,|b|<5°

Intermediate latitudes:

l=0°-360°,20°<|b|<60°

Milagro


Longitude profiles b 5

Longitude Profiles |b|<5°

50-70 MeV

0.5-1 GeV

2-4 GeV

4-10 GeV


Latitude profiles inner galaxy

Latitude Profiles: Inner Galaxy

0.5-1 GeV

2-4 GeV

50-70 MeV

4-10 GeV

20-50 GeV


Latitude profiles outer galaxy

Latitude Profiles: Outer Galaxy

0.5-1 GeV

50-70 MeV

2-4 GeV

4-10 GeV


Anisotropic inverse compton scattering

Anisotropic Inverse Compton Scattering

  • Electrons in the halo see anisotropic radiation

  • Observer sees mostly head-on collisions

Energy density

e-

R=4 kpc

small boost &

less collisions

e-

head-on:

large boost &

more collisions

Z, kpc

γ

γ

γ

Important @ high latitudes !

sun


Extragalactic gamma ray background

Extragalactic Gamma-Ray Background

EGRB in different

directions

Predicted vs. observed

E2xF

Sreekumar et al. 1998

Elsaesser & Mannheim,

astro-ph/0405235

Strong et al. 2004

E, MeV

  • Blazars

  • Cosmological neutralinos


Distribution of cr sources gradient in the co h 2

Distribution of CR Sources & Gradient in the CO/H2

CR distribution from diffuse gammas (Strong & Mattox 1996)

SNR distribution (Case &

Bhattacharya 1998)

Pulsar distribution Lorimer 2004

sun

XCO=N(H2)/WCO:

Histo –This work, Strong et al.’04

------Sodroski et al.’95,’97

1.9x1020 -Strong & Mattox’96

~Z-1 –Boselli et al.’02

~Z-2.5 -Israel’97,’00, [O/H]=0.04,0.07 dex/kpc


Again diffuse galactic gamma rays

Again Diffuse Galactic Gamma Rays

Very good agreement !

More IC in the GC –better agreement !

2-4 GeV

The pulsar distribution vs. R falls too fast OR larger H2/CO gradient


Challenges in astrophysics of cr knee rays

E.Bloom’05


Matter dark matter dark energy

Matter, Dark Matter, Dark Energy…

Ω≡ρ/ρcrit

Ωtot =1.02 +/−0.02

ΩMatter=4.4%+/−0.4%

ΩDM =23% +/−4%

ΩVacuum=73% +/−4%

SUSY DM candidate has also other reasons to exist -particle physics…

“Supersymmetry is a mathematically beautiful theory,

and would give rise to a very predictive scenario,

if it is not broken in an unknown way which unfortunately

introduces a large number of unknown parameters…”

Lars Bergström (2000)


Where is the dm

Where is the DM ?!

Flavors:

  • Neutrinos ~ visible matter

  • Super-heavy relics: “wimpzillas”

  • Axions

  • Topological objects “Q-balls”

  • Neutralino-like, KK-like

    Places:

  • Galactic halo, Galactic center

  • The sun and the Earth

    Tools:

  • Direct searches

    • low-background experiments (DAMA, EDELWEISS)

    • neutrino detectors (AMANDA/IceCUBE)

    • Accelerators (LHC)

  • Indirect searches

    • CR, γ’s (PAMELA,GLAST,BESS)

from E.Bloom presentation


Example global fit diffuse s pbars positrons

Example “Global Fit:” diffuse γ’s, pbars, positrons

GALPROP/W. de Boer et al. hep-ph/0309029

  • Look at the combined (pbar,e+,γ) data

  • Possibility of a successful “global fit” can not be excluded -non-trivial !

Supersymmetry:

  • MSSM (DarkSUSY)

  • Lightest neutralino χ0

  • mχ ≈ 50-500 GeV

  • S=½ Majorana particles

  • χ0χ0−> p, pbar, e+, e−, γ

γ

pbars

e+


Challenges in astrophysics of cr knee rays

Longitude and Latitude Distr. E >0.5 GeV

Out of the plane (± 300 in long..)

In the plane (± 50 in lat.)


Challenges in astrophysics of cr knee rays

z

Rotation Curve

x

y

DM

halo

2003, Ibata et al, Yanny et al.

disk

bulge

Inner Ring

Outer Ring

Executive Summary –de Boer et al. astro-ph/0408272

Observed

Profile:

EGRET data

+ GALPROP

Expected

Profile (NFW)

xy

xy

Isothermal

Profile

v2M/r=cons.

and

M/r3

1/r2

for const.

rotation

curve

xz

xz

Halo profile


Challenges in astrophysics of cr knee rays

PAMELA: Secondary to Primary ratios

  • LE: sec/prim peak: one instrument -no cross calibration errors

  • HE: Dxx(R)

plots: M.Simon

Page Number


Pamela positrons

PAMELA positrons

After 3 years

  • A factor of 2 will become statistically significant

  • Measuring absolute flux not ratio

  • Solar minimum conditions


Pamela antiprotons

PAMELA antiprotons

After 3 years


Dm in diffuse rays spectral signature

DM in Diffuse γ-rays: Spectral Signature

GLAST LAT

Smoking gun!

Ullio et al.2002


The excess clues from the local medium

Positions of the local clouds

sun

Pohl et al.2003

Digel et al.2001

The Excess: Clues from the Local Medium

Observations of the local medium in different directions, e.g. local clouds, will provide a clue to the origin of the excess (assuming it exists). Inconclusive based on EGRET data

Will GLAST see the excess?

Yes

No

  • Poor knowledge of

  • π0-production cross section:

  • better understanding of

  • π0-production

  • Dark Matter signal:

  • look for spectral signatures in cosmic rays (PAMELA, BESS, AMS) and in collider experiments (LHC)

Possibility:

cosmic-ray spectral variations.

Further test: look at more distant clouds

EGRET data


Challenges in astrophysics of cr knee rays

σ

σ


Challenges in astrophysics of cr knee rays

A.Morselli


Glast lat simulations

GLAST LAT simulations

EGRET intensity (>100 MeV)

|b| < 20°

LAT simulation (>100 MeV)

Seth Digel


Glast lat the gamma ray sky

Simulated LAT (>1 GeV, 1 yr)

Simulated LAT (>100 MeV, 1 yr)

GLAST LAT: The Gamma-Ray Sky

This is an animation that steps from 1. EGRET (>100 MeV), to 2. LAT (>100 MeV), to 3. LAT (>1 GeV)

EGRET

(>100 MeV)

Seth Digel


Conclusions i

B/C

Be10/Be9

Zh increase

Ek, MeV/nucleon

Ek, MeV/nucleon

Conclusions I

Accurate measurements of nuclear species in CR, secondary positrons, antiprotons, and diffuse γ-rays simultaneously may provide a new vital information for Astrophysics – in broad sense, Particle Physics, and Cosmology.

Hunter et al. region:

l=300°-60°,|b|<10°

Gamma rays: GLAST is scheduled to launch in 2007 – diffuse gamma rays is one of its priority goals

Dark Matter

CR species:New measurements at LE & HE simultaneously(PAMELA, Super-TIGER, AMS…)


Conclusions ii

Conclusions II

Antiprotons: PAMELA (2006), AMS (2008) and a new BESS-polar instrument to fly a long-duration balloon mission (in 2004, 2006…), we thus will have more accurate and restrictive antiproton data

HE electrons:Several missions are planned to target specifically HE electrons

Positrons: PAMELA (2006), AMS (2008): accurate and restrictive positron data

CERN Large Hadronic Collider – will address SUSY

In few years we may expect major breakthroughs in Astrophysics and Particle Physics !


Challenges in astrophysics of cr knee rays

Thank you !


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