Challenges in Astrophysics of CR (knee--) & γ -rays

Igor V. Moskalenko Igor V. Moskalenko (Stanford U.)(Stanford U.)

Challenges in AstrophysicsChallenges in Astrophysics

of CR (knee--) & of CR (knee--) & γγ-rays-rays

Topics covered: Intro to the relevant physics Modeling of the CR propagation and diffuse

emission Perspectives: Pamela, GLAST and other near

future missions

Igor V. Moskalenko 2 November 17, 2005 Miniworkshop/Rome2, Italy

CR Interactions in the Interstellar Medium

e+-

PPHeHe

CNOCNO

X,γ

gas

gas

ISRF

e+-

π+-

PP__

LiBeBLiBeB

ISM

diffusiondiffusion energy losses energy losses reaccelerationreacceleration convectionconvection etc.etc.

π0

synchrotron

IC

bremss

Chandra

GLAST

ACEhelio-modulation

pp

42 sigma (2003+2004 data)

HESS Preliminary

SNR RX J1713-3946SNR RX J1713-3946

PSF

B

HeHeCNOCNO Fl

ux

20 GeV/n

CR species: Only 1 location modulation

e+-

π+-

PAMELABESS

AMS


Elemental Abundances: CR vs. Solar System

CR abundances: ACE

Solar system abundances

LiBeB

CNO

F

Fe

ScTiV

CrMn

Si

Cl

Al

O

Na

S

Long propagation history…


Nuclear component in CR: What we can learn?

Propagation parameters:

Diffusion coeff., halo size, Alfvén speed,

convection velosity…

Energy markers:Reacceleration,

solar modulation

Local medium: Local Bubble

Material & acceleration sites,

nucleosynthesis (r-vs. s-processes)

Stable secondaries:

Li, Be, B, Sc, Ti, V Radio (t1/2~1

Myr): 10Be, 26Al, 36Cl,

54Mn K-capture: 37Ar,49V, 51Cr, 55Fe,

57Co

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

Heavy Z>30: Cu, Zn, Ga, Ge,

Rb

Nucleo-

synthesis:

supernovae,

early universe,

Big Bang…

Solar

modulation

Diffuse γ-raysGalactic,

extragalactic: blazars, relic

neutralino

Dark Matter (p,đ,e+,γ)-


Diffuse Galactic Gamma-ray Diffuse Galactic Gamma-ray EmissionEmission

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

Tracer of CR (p, e−) interactions in the ISM (π0,IC,bremss):o Study of CR species in distant locations (spectra & intensities)

CR acceleration (SNRs, pulsars etc.) and propagationo Emission from local clouds → local CR spectra

CR variations, Solar modulationo May contain signatures of exotic physics (dark matter etc.)

Cosmology, SUSY, hints for accelerator experimentso Background for point sources (positions, low latitude sources…)

Besides:o “Diffuse” emission from other normal galaxies (M31, LMC,

SMC) Cosmic rays in other galaxies !

o Foreground in studies of the extragalactic diffuse emissiono 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)

ψψ((rr,p,t),p,t) – – density per total momentum

df

Vpdt

dp

p

ppppDp

p

Vxx

D

prqt

tpr

3

1

22

][

),(),,(

sources (SNR, nuclear reactions…)sources (SNR, nuclear reactions…)

convection convection (Galactic wind)

diffusiondiffusion

diffusive diffusive reacceleration reacceleration

(diffusion in the momentum space)

E-lossE-loss

fragmentationfragmentation radioactive decayradioactive decay

+ boundary conditions


CR Propagation: Milky Way Galaxy

Halo

Gas, sources

100

pc 40 kpc

4-12

kpc

0.1-0.01/ccm

1-100/ccm

Intergalactic space

1 kpc ~ 3x1018 cm

R Band image of NGC8911.4 GHz continuum (NVSS), 1,2,…64 mJy/ beam

Optical image: Cheng et al. 1992, Brinkman et al. 1993Radio contours: Condon et al. 1998 AJ 115, 1693

NGC891

Sun

“Flat halo” model (Ginzburg & Ptuskin 1976)


A Model of CR Propagation in the Galaxy

Gas distribution (energy losses, Gas distribution (energy losses, ππ00, brems), brems)

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

Nuclear & particle production cross sectionsNuclear & particle production cross sections

Gamma-ray production: brems, IC, Gamma-ray production: brems, IC, ππ00

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

Solve transport equations for all CR speciesSolve transport equations for all CR species

Fix propagation parametersFix propagation parameters

“Precise” Astrophysics


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

4a-f

EGRET data


Reacceleration Model vs. Plain Reacceleration Model vs. Plain DiffusionDiffusion

Plain Diffusion

(Dxx~β-3 R0.6)

DiffusiveReacceleration

B/C ratio

Antiproton flux

Antiproton flux

B/C ratio


Positron Excess ?

HEAT (Beatty et al. 2004)

GALPROP

GALPROP

1E, GeV

10

e+/e e+/e

HEAT 2000 HEAT 1994-95

HEAT combined

1E, GeV

10

Q: Are all the excesses connected?Q: Are all the excesses connected?

A: “Yes” and “No”A: “Yes” and “No”

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

Systematic errors of different detectors

E > 6 GeV


CR Source Distribution

SNR source

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)

Lorimer 2004

PulsarsCR afterpropagation

diffuse γ-raydistribution


Injection intothe ISM

Life and death of e+

Energy loss

PositroniumIn flight

Direct annihilationwith bound electrons

RadiativeCapture Grains

ChargeExchange

2223

Direct annihilationwith free electrons

Positronium

Thermalisation

All sky view of 511 keV emissionKnödlseder et al 2005

Positron Annihilation Line

Positron Annihilation Line

W.Gillard

INTEGRAL-SPI


Hypotheses…

Provide Provide good agreementgood agreement with all with all data (diffuse gammas, pbars, e+)data (diffuse gammas, pbars, e+) CR intensity variationsCR intensity variations Dark Matter signals Dark Matter signals

Other possibilities:Other possibilities:

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

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


Diffuse emission models

0.5-1 GeV

>0.5 GeV

Dark MatterCosmic Ray

Spectral VariationsEGRET “GeV Excess”

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

Dark MatterCR spectral variations

Both have their pros & cons.

from Strong et al. ApJ (2004)from de Boer et al. A&A (2005)

from Hunter et al. ApJ (1997)


CR Variations in Space & Time

More frequent SN in the spiral arms

Historical variations Historical variations of CR of CR intensityintensity: : ~40kyr~40kyr ( (1010Be in Be in South Polar ice), South Polar ice), ~2.8Myr ~2.8Myr ((6060Fe in deep sea FeMn Fe in deep sea FeMn crust)crust)

Konstantinov et al. 1990

Electron/positron energy losses

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

SN

R n

um

ber

den

sit

y

R, kpc


Electron Fluctuations/SNR stochastic events

GeV electrons 100 TeV electronsGALPROP/Credit S.Swordy

Energy losses

107 yr

106 yr

Bremsstrahlung

1 TeV

Ionization

Coulomb

IC, synchrotron

1 GeV

Ekin, GeV

E(d

E/d

t)-1,y

r

Electron energy loss timescale:

1 TeV: ~300 kyr 100 TeV: ~3 kyr


GeV excess: Optimized/Reaccleration model

Uses Uses all skyall sky and antiprotons & gammas and antiprotons & gammas to fix the nucleon and electron spectrato fix the nucleon and electron spectra

Uses Uses antiprotonsantiprotons to fix to fix the the intensityintensity of CR nucleons @ HE of CR nucleons @ HE

Uses Uses gammasgammas to adjust to adjust the nucleon spectrum at LEthe nucleon spectrum at LE the the intensity intensity of the CR electrons of the CR electrons (uses also synchrotron index)(uses also synchrotron index)

Uses EGRET data Uses EGRET data up to 100 GeVup to 100 GeV

protonsprotonselectronselectrons

x4x4

x1.8

antiprotonsantiprotons

EEkk, GeV, GeV

EEkk, GeV, GeV

EEkk, GeV, GeV


Secondary e± are seen in γ-rays !

Lots of new effects !

Improves an agreement at LE

brems

IC

Heliosphere: e+/e~0.2

electronselectrons

positronspositrons

sec.


Diffuse Gammas at Different Sky RegionsDiffuse Gammas at Different Sky Regions

Intermediate latitudes:l=0°-360°,10°<|b|<20°

Outer Galaxy:l=90°-270°,|b|<10°

Intermediate latitudes:l=0°-360°,20°<|b|<60°

Inner Galaxy:l=330°-30°,|b|<5°

Hunter et al. region:l=300°-60°,|b|<10°

l=40°-100°,|b|<5°

corrected

Milagro


Longitude Profiles |b|<5Longitude Profiles |b|<5°°

50-70 MeV

2-4 GeV

0.5-1 GeV

4-10 GeV


Latitude Profiles: Inner Galaxy

50-70 MeV 2-4 GeV0.5-1 GeV

4-10 GeV 20-50 GeV


Latitude Profiles: Outer Galaxy

50-70 MeV

2-4 GeV

0.5-1 GeV

4-10 GeV


Anisotropic Inverse Compton Scattering

Electrons in the halo see anisotropic radiation Observer sees mostly head-on collisions

e-

e-

head-on:large boost &more collisions

γγ

small boost &less collisions

γ

sun

Energy density

Z, kpc

R=4 kpc

Important @ high

latitudes !


Extragalactic Gamma-Ray BackgroundExtragalactic Gamma-Ray Background

Predicted vs. observedPredicted vs. observed

E, MeVE, MeV

EE22xFxF

Sreekumar et al. 1998Sreekumar et al. 1998

Strong et al. 2004Strong et al. 2004Elsaesser & Mannheim,

astro-ph/0405235

•Blazars•Cosmological neutralinos

EGRB in differentdirections


Distribution of CR Sources & Gradient in the CO/H2

CR distribution from diffuse gammas (Strong & Mattox 1996)

SNR distribution (Case &Bhattacharya 1998)

sun

XXCOCO=N(H=N(H22)/W)/WCOCO::

Histo –This work, Strong et al.’04----- -Sodroski et al.’95,’971.9x1020 -Strong & Mattox’96~Z-1 –Boselli et al.’02~Z-2.5 -Israel’97,’00, [O/H]=0.04,0.07 dex/kpc

Pulsar distribution Lorimer 2004


Again Diffuse Galactic Gamma Rays

More IC in the GC –better

agreement !

The pulsar distribution vs. R falls too fast OR

larger H2/CO gradient

Very good agreement !Very good agreement !

2-4 GeV

Igor V. Moskalenko 28 November 17, 2005 Miniworkshop/Rome2, ItalyE.Bloom’05


Matter, Dark Matter, Dark Energy…

Ω ≡ ρ/ρcrit

Ωtot =1.02 +/−0.02

ΩMatter =4.4%+/−0.4%

ΩDM =23% +/−4%

ΩVacuum =73% +/−4%“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)

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


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

Look at the combined (pbar,e+,γ) data Possibility of a successful “global fit”

can not be excluded -non-trivial !

pbars

e+

γ

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

Supersymmetry: MSSM (DarkSUSY) Lightest neutralino χ0

mχ ≈ 50-500 GeV S=½ Majorana

particles χ0χ0−> p, pbar, e+, e−,

γ


Longitude and Latitude Distr. E >0.5 GeV

In the plane (± 50 in lat.) Out of the plane (± 300 in long..)


x y

z

2003, Ibata et al, Yanny et al.

Outer RingInner Ring

DM halo

diskbulge

Rotation Curvexy

xz

xy

xz

Expected Profile (NFW)

Halo profile

Isothermal Profile

v2M/r=cons.and

M/r3

1/r2

for const.rotation

curve

Observed Profile: EGRET data+ GALPROP

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

Page Number

PAMELA: Secondary to Primary ratios

plots: M.Simon

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

HE: Dxx(R)


PAMELA positrons

A factor of 2 will become statistically significant

Measuring absolute flux not ratio

Solar minimum conditions

After 3 years


PAMELA antiprotons

After 3 years


DM in Diffuse γ-rays: Spectral Signature

Ullio et al.2002

Smoking gun!

GLAST LAT


Pohl et al.2003

sun

Positions of the local clouds

The Excess: Clues from the Local The Excess: Clues from the Local MediumMedium

Digel et al.2001

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

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

Will GLAST see the excess?

EGRET data


σσ


A.Morselli


GLAST LAT simulations

EGRET intensity (>100 MeV)

LAT simulation (>100 MeV)

|b| < 20°

Seth Digel


GLAST LAT: The Gamma-Ray Sky

EGRET(>100 MeV)

Simulated LAT (>100 MeV, 1 yr)Simulated LAT (>1 GeV, 1 yr)

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

Seth Digel


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.

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

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

Hunter et al. region:l=300°-60°,|b|<10°

Dark Matter

Zh increase

Be10/Be9

EEkk, MeV/nucleon, MeV/nucleon

B/C

EEkk, MeV/nucleon, MeV/nucleon


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

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

CERN Large Hadronic Collider – will address SUSY

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


Thank you !

Challenges in Astrophysics of CR (knee--) & γ -rays

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