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Unveiling the nature of the sources of High-Energy-

Recent discoveries from TeV and X-ray observations

Fabio AceroLUPM, Montpellier

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Outline

• Why using HE observations to search for CR accelerators

• Opportunities in the unidentified sources

• Evidence of e- acceleration using X-ray observations -> The case of the PWN J0855-4644

• TeV emission from shell SNRs-> The case of the SNR HESS J1731

• The GeV-TeV connection with the Fermi satellite

• CTA, the next generation of Cherenkov telescope

Searching for the origins of Galactic CRs

shock wave

PSR

PWN

SNR

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Cosmic rays accelerators

• Where are accelerated hadrons (99% of CRs) ? CRs are deflected by Galactic B field

• What is the contribution of PWNe ?

• Candidates need to reproduce observed flux and Emax

Ex : CasA SNR Ex : Crab PWN

X-rays, Chandra X-rays, Chandra

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The unidentified sources in HE surveys

INTEGRAL IBIS/ISGRI Fermi-LAT H.E.S.S.

Nb of sources

Unid. src

PossibleGal.

counterpart

723

210

binaries, PSR/PWN

Bird+ 10 Abdo+ 10 Chaves+08

1451 60

630 30

PSR, middle aged SNR

SNR/MC

PWN, young SNR,

SNR/MC

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Cherenkov astronomy

30 out ~60 Galactic sources are unidentified

Renaud 09

Fabio Acero

SNRs at TeV energies

• Possibility to directly investigate proton acceleration through hadronic process

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Shell-morphologyyoung SNRs: t~1kyr

Interacting with molecular cloudsolder SNRs: t~10 kyrs

Vela Jr, RX J1713-3946, RCW 86 (?), SN 1006

IC 443, W28, W51

RX J1713 -3946 IC 443

Fabio Acero

Radio Rayons X Rayons γ

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Nature of the TeV emission : hadronic/leptonic

SN 1006

Rayons X

GeV TeV

B,Emax(e-)

Synchrotron nISM

pCR-pISM 2 γ

Uph

Inverse Compton

Tanaka et al., 08

Fabio Acero

PWNe at TeV energies

• Leptonic TeV emission : Probing the Magnetic field• SED modelization difficult. One population model not valid (e.g. Vela-X)

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Young PWNe Offset PWNe

Crab, G0.9+0.1, MSH 15-52, G21.5-0.9, Kes 75... Vela-X

MSH 15-52

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Discoveries in X-rays :A new PWN in the VelaJr region

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Motivations to observePSR J0855-4644

ROSAT > 1.3 keV HESS excess map (Aharonian+07)

Pulsar parametersP = 64 ms

Ė = 1.1 x 1036 ergs/sd=4 kpc (from DM)

Kramer+03, Redman+05

VelaJr SNR VelaJr SNR

XMM pointings

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Discovery of a new PWN in the VelaJr region

VelaJr SE rim

1.2-6.0 keV

PWN

XMM-Newton

PWN radial profile

point source subtracted

1.2-6.0 keV

PWNPSR

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1.2-2.0 keV

σ=61.2’’±2.2’’

60’’

PWN morphology

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2.0-4.0 keV

σ=53.2’’±1.8’’

60’’

PWN morphology

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Pulsar parameters

P = 64 ms Ė = 1.1 x 1036 ergs/s

τc=150 kyr

nH=0.40±0.08x1022cm-2

Γpsr=1.25±0.06F2-10keV=(2.2±0.4)x10-13

(ergs/cm2/s)

kT and nH from Velathermal emission fixed

from the nebula

MOS1MOS2

PSR absorbed

powerlaw

Veladiffusethermal emission

PSR J0855-4644

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PSR distanceAbsorption column

• PSR is likely to lie at a distance <2kpci.e. in the foreground of the Vela Molecular Ridge (VMR, d=1 kpc)

•nH(VelaJr SE rim)~0.5x1022 cm-2

and dist ~0.7 kpc

12CO

12CO

HI

Total

VMR

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Changing distance changes everything

• A nearby energetic pulsar

• Why wasn’t it discovered before ?-> Embeded in a complex region

Only psr with Edot > 1035 ergs/s selected

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Morphology

Vela PSR

3C58 PSR

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Jet structures ?

PSR J0855-4644

0°

Chandra proposal has been submitted

Chandra FWHM : 1’’XMM FWHM : 6’’

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Discoveries at TeV energies :HESS J1731 a new TeV shell type SNR

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PostDoc : HESS J1731-347

0.5°

F. Acero for the HESS collaboration, 2011

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PostDoc : HESS J1731-347

• Only the 4th example of gamma TeV shell SNR !

• First shell SNR discovered based on Gamma observations !!

• Non-thermal shell seen in radio, X-rays, Gamma-rays

0.5°

F. Acero for the HESS collaboration, 2011

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HESS J1731-347 & J1729-245Radial profile

• Spatially coincident with radio shell

• 4th TeV SNR with significant shell morphology

Radial profilesGamma-ray excess

0.5°

F. Acero for the HESS collaboration, 2011

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HESS J1731-347Distance estimate

d=3.2 kpc ?

SNR

NH from X-rays NH from 12CO+HI integrated up to 3.2 kpc

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Clouds in the line of sight

Molecular CloudM=105 Msun

d= 6 kpc

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HESS J1731 - Spectral energy distribution

Leptonic model

Hadronic modelWp= 6x1050 (n/1cm-3)-1(d/3.2kpc)2 ergs

ESN~1051 ergsB= 50 μG

+ Spectral slope- Energetic budget

We= 3x1047 (d/3.2kpc)2 ergsB= 25 μG

+ Reasonable energetic budget- Spectral slope not reproduced

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HESS J1731 - What about Fermi ?

Fermi Test Significance mapOnly photons of E > 1 GeVSky model : Gal. and extragal.

Velocity integrated 12CO map (Dame+01)

White : HESS contoursBlack Fermi 1yr catalog sources

RX J1713-3946 : hadronic or leptonic ?

Abdo et al., 2011

LeptonicHadronic

Blue --- (Ellison, 2010) :B=10 μG

nH=0.25 cm-3 (uniform ISM)

Red --- (Berezhko 2010) : B=142 μG

nH=0.25 cm-3 (bubble cavity)Wp=0.45 x 1050 ergs

γ-ray emission is dominated by leptonic processes

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Have we found the Galactic CRs accelerators ?

• TeV emission seems dominated by leptonic scenario ntarget too weak for a significant hadronic signal

• Importance of multi-λ observations for the modelization (distance, ntarget)

• Search for other young SNRsexpected number in the Galaxy ~40

• Other sources for CRs ? Superbubbles?

• Sources possibly already detected ~50% of Fermi&HESS src are unId.

• Joint H.E.S.S.II-Fermi + multi-λ counterpart search

Shell SNRs

RX J1713 HESS J1731

VelaJr SN 1006

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The Cherenkov Telescope Array

• Large array of telescopes (3 different sizes) operating in 100 GeV < E < 100 TeV

• A factor of 5-10 in sensitivity and ~3 in angular resolution

• Extend our horizon of detectability for SNRs and PWNe

Low energyMid energy

High energy

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• Shell morphology spatially resolved for only ~20% of the SNRs

• Source confusion will be higher for CTA in Galactic central regions

• Multi-λ observations will be critical for CTA for source identification

Fraction of SNRs visible from Namibia for the luminosity of RX J1713 and an homogenous Galactic

Scan of 20h

Towards a complete census of young SNRs in our Galaxy

M. Renaud & F. Acero

CTA SNR horizon

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CTA simulation : MorphologyRX J1713

PSF

HESS r68% (PSF) =0.08° CTA r68%(PSF)=0.04°

Aharonian et al, 2007M. Renaud & F. Acero

Observation CTA simulation based on the X-ray map

Tobs=50 h

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CTA simulation : MorphologyRX J1713

PSF

HESS r68% (PSF) =0.08° CTA r68%(PSF)=0.02°

Aharonian et al, 2007M. Renaud & F. Acero

Observation CTA simulation based on the X-ray map

Tobs=50 h

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Thank you !

H alpha Radio X-ray Gamma -ray

SN 1006 supernova remnant