M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Latest results on SNRs and PWNe in the Milky Way as seen in VHE gamma-rays
Matthieu Renaud
AstroParticule et CosmologieUMR 7164, Université Paris 7
Chaves et al. HESS (2008)
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Outline: TeV astronomy
Individual sources & multi-wavelength observations
● Shell-type SNRs
● Plerionic SNRs (« PWNe »)– Known PWNe
– PWN candidates
Other sources & surveys
● Some cases in between...
● …diffuse VHE emission?
Concluding remarks and perspectives
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Shell-type SNRs: RX J1713.7-3946
Aharonian et al. (2007a)
H.E.S.S. image1-3 keV ASCA contours
Γ = 2.04 ± 0.04E
c = 17.9 ± 3.3 TeV
Index constant across SNR
~1°
Nature of the TeV emission:Inverse-Compton or π0 decay?
Particles of >100 TeV inside the SNR...
d = 1.3 ± 0.4 kpc... AD 393 ? No thermal X-ray emission: n < 0.02 cm-3
(Cassam-Chenaï et al. 2004)
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Shell-type SNRs: RX J0852-4622 (aka Vela Jr)
Aharonian et al. (2007b)
H.E.S.S. image
Power-law Γ = 2.24 ± 0.04with indication of a cutoff?
Nature of the TeV emission:Inverse-Compton or π0 decay?
Particles of ~100 TeV inside the SNR...
~2°
d = 0.25 -1 kpc... age ? No thermal X-ray emission: n < 0.03 cm-3
(Slane et al. 2001)
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Shell-type SNRs: RCW 86
Aharonian et al. (2009)
H.E.S.S. Image & 4,5,6 σ contours
Γ = 2.54 ± 0.12 (no cutoff)
Both shell and uniform sphere fit the data...
~0.6°
Nature of the TeV emission:Inverse-Compton or π0 decay?
Particles of ~100 TeV inside the SNR...
vs ~ 2700 km/s... SN 185? d = 1 kpc?
Faint thermal X-ray emission (Vink et al. 2006)
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Shell-type SNRs: SN 1006
Naumann-Godo et al. (HESS Collaboration, 2008)
H.E.S.S. Image & Chandra (smoothed) contours
~0.5°
See the talk by M. Naumann-Godoon thursday for more details...
Nature of the TeV emission:Inverse-Compton or π0 decay?
Particles of ~100 TeV inside the SNR...
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Shell-type SNRs
RX J1713.7-3946 (Berezhko & Völk 2008)
Pro-hadrons:Amplified B-field from the thinness of X-ray filaments (& variability) Pro-leptons:Lack of thermal X-ray emissionNature of X-ray filamentsLimitations:Size of filaments << VHE PSFsNon-imaging instruments > 10 keV
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
VHE Pulsar Wind Nebulae & candidates
Half of the H.E.S.S. sources is likely associated with a PSR
Young PWNe: Crab nebula, MSH 15-52... and G21.5-0.9, Kes 75
Djannati-Ataï et al. HESS (2008)Terrier et al. HESS (2008)
PSR J1848-0258 (Gotthelf 2000) τ
c = 723 yr, Ė
36 = 8.3
d ~ 6 kpc (Leahy & Tian 2008)
PSR J1833-1034 τ
c = 4.7 kyr, Ė
36 = 33, d ~ 5 kpc
age < 1kyr (Biethenholtz et al. 2008)
Particle-dominated PWNe (B < B
eq)
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
VHE Pulsar Wind Nebulae & candidates
Aharonian et al. (2006a)
PSR B0833-45
Aharonian et al. (2006b)
HESS J1825-137 / PSR J1826-1334 HESS J0835-455 / PSR B0833-45τ
c = 21.4 kyr, Ė
36 = 2.8, O~13 d
4kpc pc τ
c = 11.3 kyr, Ė
36 = 6.9, O~1.5 d
300pc pc
Half of the H.E.S.S. sources is likely associated with a PSR
Evolved (offset) PWNe: J1825 and Vela X (De Jager & Djannati-Ataï 2008)
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
VHE Pulsar Wind Nebulae & candidates
Association based on:
Presence of a nearby (and energetic) PSR
Theoretical background– Particle acceleration in PSR/PWN (Arons 2007, Bucciantini 2008)
– Evolution of a PWN in the ISM (Blondin et al. 2001, van der Swaluw et al. 2004)
Characteristics:
Inhomogeneous ISM and/or high vPSR
Evolved systems (τc ≥ several kyrs)
Low B (a few μG) in the VHE emissive region (de Jager & Djannati-Ataï 2008)
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
VHE Pulsar Wind Nebulae & candidates
HESS J1809-193 / PSR J1809-1917 (Aharonian et al. 2007, Renaud et al. HESS 2008)
PSR J1809-1917: τc = 51 kyr, Ė
36 = 1.8,
O~7 d3.5kpc
pc, L1-10TeV
/Ė ~ 0.015 d23.5kpc VLA 1.4 GHz (Brogan et al., Helfand et al. 2006)
PSR J1809
Kargaltsev & Pavlov (2007)
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
VHE Pulsar Wind Nebulae & candidates
HESS J1356-645 / PSR J1357-6429 ( Renaud et al. HESS 2008, Aharonian et al. in prep)
PSR J1357-6429: τc = 7.3 kyr, Ė
36 = 3.1,
O~5 d2.5kpc
pc, L1-10TeV
/Ė ~ 0.002 d22.5kpc
Zavlin (2007)
3 SNR candidates (Duncan et al. 1997) …But extended radio emission seenat 0.84, 2.4, 4.85 GHz... «relic» PWN?
Parkes 2.4 GHz image& H.E.S.S. contours
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Some cases in between: HESS J1731-347
HESS image & 4-7σ contours
MGPS 843 MHz image ROSAT (green) contours
Aharonian et al. (2008a)
1.4 GHz SGPS image(Tian et al. 2008)
A new shell-type SNR G353.6-0.7 (Tian et al. 2008)
Non-thermal shell-type radio emission with R ~ 0.25°HI absorption towards adjacent HII region : d = 3.2 ± 0.8 kpc → R ~ 14 d
3.2kpc pc
ROSAT emission coincident with lower half of the SNR... thermal emission? age?
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Some cases in between: CTB complex
Updated VHE resuts on CTB 37B & Chandra (Aharonian et al. A&A, 2008b, 486, 829)Discovery of CTB 37A & XMM / Chandra (Aharonian et al. A&A, 2008a, 490, 685)
MGPS 843 MHz contours
d = 5-9 kpc (Brand & Blitz 1993)age > 1500 yrs... AD 393? (Clark et al. 1975) No maser emission
rms = 2.6' ± 0.6' compatible with Rshell
~ 5'Γ = 2.65 ± 0.19F
= 1.8 [1.3-2.4] % Crab (0.5 -10 TeV)
Two SNRs, d ~ 11 kpc (Caswell et al. 1975)age > 1500 yrs... AD 393? (Clark et al. 1975)Masers & CO clouds (Reynoso et al. 2000)
rms = 4' ± 1' compatible with Rshell
~ 5'Γ = 2.30 ± 0.13F
= 2.8 [2.2-3.6] % Crab (0.5 -10 TeV)
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Lots of « sources » in between...!
Aharonian et al. (2008b)
Aharonian et al. (2006)
Aharonian et al. (2008c)
Accelerator (i.e. SNR) – target (i.e. MC)
Delayed VHE γs from MC as a probe of Galactic PeVatrons (Gabici et al. 2007a,b)
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Galactic diffuse VHE emission
Milagro survey of the Northern sky (Abdo et al. 2007a,b & 2008)
π0
ICtotal
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
H.E.S.S. versus Milagro: sources or diffuse emission?
5 HESS sources30° < l < 65°-2° < b < 2°
HESS J1848-010HESS J1912+101HESS J1857+026HESS J1858+020IGR J18490-0000
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Chaves et al. HESS (2008)
H.E.S.S. versus Milagro: sources or diffuse emission?
> 20% of the Milagro diffuse emission is due to unresolvedsources... detected by HESS
Compatible with the expectationsof Casanova & Dingus (2008)
But need of uniform survey...
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Concluding remarks
More than 60 VHE Galactic sources
● 5-9 shell-type SNRs
● 22-26 PWNe (& candidates)
● 20-30 unidentified
● VHE-ISM associations
● Diffuse emission (GC, Cygnus)
● 1-2 WR and 4-6 binaries
Madrid & Macchetto (2009)(2006)
Uniform disk(α = -1)
Spiral arms(α = -0.6)
?
Let's keep on doing (HE-)VHE astronomy with Fermi, H.E.S.S.-II, Magic-II, VERITAS...
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Shell-type SNRs
Loss-limited filaments?(Vink & Laming 2003, Berezhko & Völk 2004,
Völk et al. 2005, Parizot et al. 2006)
B
Ne(E)
rs
Magnetically-limited filaments?(Pohl, Yan & Lazarian 2005)
B
Ne(E)
rs
M. Renaud « SNRs & PWNe in the VHE domain » 44th Rencontres de Moriond, feb 2009
Some cases in between: CTB complex
1-5 keV Chandra (σ=50'') image
Point-like source
HESS J1713-381
Diffuse thermal (~0.7 keV) X-ray emission{v
s > 800 km/s ; age < 5 kyr} & n ~ 0.5 cm-3
No X-ray PWN nor NT X-rays from the shellHadronic scenario → η ~ 0.4 E-1
51 d2
7kpc n-1
0.5
1.2-2.5 keV Chandra image843 MHz & COcontours
3-7 keV
Diffuse thermal (~0.8 keV) X-ray emissionExtended NT X-ray emission but no PSR
No NT X-rays from the shell« Relic » VHE PWN?
HESS J1714-385