Ullrich SchwankeHumboldt University, Berlin,

for the H.E.S.S. Collaboration

Observations of Shell-type Supernova Remnants with H.E.S.S.

Overview Introduction: supernova remnants (SNR) as possible

cosmic ray sources What we now from X-rays H.E.S.S. results and interpretation

RX J1713.7-3946 (“RX J1713”) - details RX J0852.0-4622 (“Vela Junior”) – detailed 2nd

paper soon to come Summary and outlook

Are SNRs the sources of cosmic rays ?

SNRs as accelerators for hadronic cosmic rays

Diffuse shock acceleration predicts power law spectrum E-

2.0..2.2

Conversion efficiency of O(10%)

Exploring SNRs using secondary x-rays and gamma-rays

Are SNRs the sources of cosmic rays ?

SNRs as accelerators for hadronic cosmic rays

Diffuse shock acceleration predicts power law spectrum E-

2.0..2.2

Conversion efficiency of O(10%)

Exploring SNRs using secondary x-rays and gamma-rays radio x-ray TeV energy

ener

gy fl

ux

Are SNRs the sources of cosmic rays ?

SNRs as accelerators for hadronic cosmic rays

Diffuse shock acceleration predicts power law spectrum E-

2.0..2.2

Conversion efficiency of O(10%)

Exploring SNRs using secondary x-rays and gamma-rays radio x-ray TeV energy

ener

gy fl

ux electron accelerator

synchrotronemission

inverseCompton

e

Are SNRs the sources of cosmic rays ?

SNRs as accelerators for hadronic cosmic rays

Diffuse shock acceleration predicts power law spectrum E-

2.0..2.2

Conversion efficiency of O(10%)

Exploring SNRs using secondary x-rays and gamma-rays radio x-ray TeV energy

ener

gy fl

ux

synchrotronemission

e

hadron accelerator

0 production

0 p

X-Ray Observations

SN 1006 (CHANDRA)Bamba et al. (2003)

2-10 keV

0.4-0.8 keV

X-Ray Observations

SN 1006 (CHANDRA)Bamba et al. (2003)

2-10 keV

0.4-0.8 keV

X-Ray Observations

E. Parizot et al. (2006)

Electrons leaving acceleration region move downstream by advection and diffusion

Synchrotron losses

Downstream size of filaments upper limit on synchrotron loss time and lower limit on B field

upstream

downstream

shock

RX J1713.7-3946

2o

0.75o

Largest known TeV source

RX J0852.0-4622

H.E.S.S. TeV Observations

RX J1713.7-3946H.E.S.S. TeV Observations

2o

0.75o

Largest known TeV source

RX J0852.0-4622

RX J1713

Discovery in ROSAT All-Sky Survey

Mostly non-thermal X-rays D ~ 1 kpc CANGAROO observed TeV

excess from western rim

ROSAT 1996

H.E.S.S. 2004

H.E.S.S. 4-telescope obervations (33 h live-time)

Zenith angle 15-60° Shell resolved!

Correlation with X-rays Correlation coefficient between TeV -rays

(HESS) and X-rays (ASCA) is ~80% Shocks -rays

RX J1713: Spectrum

2003 and 2004 spectra compatible

Photon index 2.260.020.15

Flux ~ 1 Crab Spectrum extends

up to 40 TeV acceleration of particles up to ~100 TeV

Deviation from pure power-law at high energies

Spatially Resolved Energy SpectraTeV photon index X-ray photon index

TeV=const. difficult to understand in electron scenario

1.8 2.0 2.2 2.4 2.6H.E.S.S.G. Cassam-Chenaï A&A 427, 199 (2004)

Electron Scenario (1/2)

E

SY IC

E

SY IC

High B field, low electron injection low IC level

Low B field, high electron injection high IC level

ener

gy fl

ux

ener

gy fl

ux

Electron Scenario (2/2)=2.2 at injection level =2.4 at injection level

Simple one-zone model Electrons and protons injected with same spectral shape; energy

losses and particle escape out of the shell were considered Need a B field of ~8 G to match flux ratio

Simple electronic models do not work too well

B=6 GB=8 GB=10 G

Hadron (+Electron) Scenario

Injection spectrum: power-law (=1.98) with exponential cutoff (at 120 TeV)

Injected energy 1051 erg, electron-to-proton ratio 5 10-4

B field ~35 G, H density 1.5 cm-3

Summary & Outlook Two shell-type SNRs established as TeV -ray

sources Both sources were resolved; TeV morphology very

similar to X-ray morphology First ever spatially resolved TeV energy spectra (for

RX J1713) Observed flux is ~1 Crab, photon index ~2.2 Question of electron or hadron acceleration remains

difficult to answer (for the few objects we have) H.E.S.S. II and GLAST will determine energy spectra

in GeV domain