SLIDE 1
Fermi acceleration under control: η Carinae
Roland Walter, Matteo Balbo, Christos Panagiotou
in prep; arXiv170502706; A&A 526, 57; A&A 524, 59
Fermi acceleration under control: Carinae Who is Car ? M 10 3 . 5 - - PowerPoint PPT Presentation
Fermi acceleration under control: Carinae Who is Car ? M 10 3 . 5 - - PowerPoint PPT Presentation
in prep; arXiv170502706; A&A 526, 57; A&A 524, 59 Roland Walter, Matteo Balbo, Christos Panagiotou Fermi acceleration under control: Carinae Who is Car ? M 10 3 . 5 M / yr L wind 2000 L Who is Car ? M 10
SLIDE 2
SLIDE 3
Who is η Car ?
˙ M ∼ 103.5 M/yr
Lwind ≈ 2000 L
SLIDE 4
Orbital variability
Lπ0 ≈ 10 L⊙
FERMI INTEGRAL
0.3 - 10 GeV X-rays
SLIDE 5
gamma
electrons
gamma
electrons
B (G) 400
e- spectrum smooth IC spectrum
Parkin et al, 2011
3D hydro simulations
(Thermal simulations from Parkin et al, 2011)
SLIDE 6
B (G) 400
e- spectrum smooth IC spectrum
Parkin et al, 2011
3D hydro simulations
photons photons
(Thermal simulations from Parkin et al, 2011)
SLIDE 7
η Car γ-ray light-curves
0.3 - 10 GeV 10 - 300 GeV
L(π0)~n2 i.e. hadrons L(therm)~n2 L(IC)~n i.e. electrons
SLIDE 8
η Car γ-ray light-curves
0.3 - 10 GeV
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Hadronic spectrum
Apastron Periastron Averaged
knee of the CR spectrum
SLIDE 10
What happened during last periastron ?
Possible interpretation
Larger wind clumpiness or dM/dt ➙ Stronger thermal emission (~ n2)
Corcoran (2015)
x 5.5 x 10 3-10 GeV
➙ lower Υmax,p
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Energetics
Thermal X-rays: 25 L⊙ Synchrotron: < 0.1 L⊙ Electron acceleration: 50 L⊙ π0 emission: 10 L⊙ neutrino: ~ 10-9 GeV s-1 cm-2 (above 10 TeV) η Carinae shows evidences for electronic and hadronic acceleration Electron spectral index is compatible with 2.25 Proton cutoff energy ≳1013 eV, higher than measured in middle aged SNR Efficiency of particle acceleration ~ 1% (Spitkovsky’s simulations: 10%) With this efficiency, a massive star could accelerate ~ 1049 ergs of cosmic-rays, as much as an average SNR.
M17 (Omega nebula) Chandra (0.5-2/2-8 keV) LX=1 L⊙ 10% of OB stellar wind luminosity
(Townsley et al., 2005)
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Lepto-hadronic or hadronic ?
e-Astrogam will tell CTA will probe γ-γ absorption, wind structure and high energy cutoff Variability expected at periastron
Ohm et al, 2015
e
- A
s t r
- g
a m ( 1 y ) CTA (50hrs)
SLIDE 13
Conclusions
- 1. Low energy lightcurve (0.3-10 GeV)
- Modulation is driven by the orbital motion.
- Flux varied by 50% in less than 40 days ➔ smaller than the homonculus
- Variability matches simulations for Bsurf ∼ 400G ➔ IC emission likely
- X-ray and gamma-ray minima consistent ➔ disappearance of CWZ
- 2. The high energy lightcurve (>10GeV) is poorly constrained
- Pion disintegration matches amplitude of variability
- Inverse Compton emission is ruled out at such energies
- Periastron are different ➔ clumpy wind ?
- Eta Carinae may accelerate as much hadrons as a SNR
- 3. Some consensus for hadronic acceleration
- 4. Prominent source for CTA and e-Astrogam
- 5. A CWB could accelerate as much cosmic-rays as an average SNR