1. PHYSICAL PROBLEMS INVOLVED
X-RAY EMISSION FROM SUPERNOVA REMNANTS Rino Bandiera – INAF – Oss. Astrof. Di Arcetri IN THE PERSPECTIVE OF NHXM
WHAT OBJECTS TO OBSERVE ?  WHAT PROBLEMS TO SOLVE ?
NUMBER OF SOURCES
PHYSICAL PROBLEMS INVOLVED
NHXM Rome 12 / 11 / 09

2. Pulsar Wind Nebulae (in the presence of a central pulsar
Shell-type SNRs
Non-relativistic shocks
In young SNRs, a reverse shock in the supernova material (ejecta)
Heating (usually soft X-rays)
Particle acceleration Ions  cosmic rays (CRs) Electrons  synchrotron
Pulsar Wind Nebulae (in the presence of a central pulsar
Ultrarelativistic MHD wind
Braked by the outer SNR medium
Termination shock
In the post-shock region, accelerated electrons + amplified magnetic field ( synchrotron)
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3. HARD X-RAYS  YOUNG SNRs Fast shock | Powerful pulsar
Cas A
SN 1006
Crab Nebula
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4. SN 1006 Age = 1000 yr Diameter = 30’ = 19 pc Distance = 2.2 kpc
AN IDEAL LABORATORY FOR
ACCELERATION PROCESSES
Koyama et al. 1995
Cassam.Chenai et al. 2008
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5. SHOCK ACCELERATION “Diffusive” (1st order Fermi) particle acceleration
Convergent flows (upstream – downstream)
Returning upstream (diffusive processes)
“SUPERNOVA PARADIGM”
A SNR origin for the Galactic CRs 10% of the kinetic energy converted into CRs
(electrons are dynamically unimportant, but essential for the diagnostics)
Highly efficient acceleration mechanisms
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6. MODIFIED SHOCKS Dynamical feedback on the shock structure
An intrinsically complex problem
Non linear / Kinetic regime
Acceleration  Streaming instabilities  Magnetic field amplified upstream  Modification of the diffusive regime  Effects on the acceleration (e.g. Caprioli et al. 2009)
Drury &Voelk 1981
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7. DIAGNOSTIC TOOLS
Limb thickness (smaller in X) If due to synchrotron lifetime  B estimate (150G, Voelk et al. 2005)
Forward / reverse shock distance
Lower if part of the
energy is in CRs
For SN 1006 forward shock/contact discontinuity ratio measurements. (Cassam-Chenai et al. 2008, Miceli et al. 2009)
Radio
0.5 – 0.8 keV
1.2 – 2 keV
(Long et al. 2003)
“Model dependent” results
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8. B vs Ee DEGENERATION
Synchrotron emissivity degeneration between B and Ee in the power-law region
Maximum energy from the gains / losses balance
Time-scale of diffusive acceleration
If acceleration is balanced by synchrotron losses the spectral upper cutoff is also B independent
NHXM Rome 12 / 11 / 09

9. In SN 1006, strong changes in cutoff
Implications: -  changes
OR - it is not in a synchrotron- dominated regime (lower estimates for B )
Rothenflug et al. 2004
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10. Cutoff shape depends on physical processes:
Synchrotron-limited + Bohm diffusion:
Age-limited + Bohm diffusion:
The importance of a spectral extension:
Comparison between age-limited and synchrotron-limited cases
Spectra up to about 30 keV, in the bright limbs
lg Eph
lg F
1-5 keV
lg Eph
lg F
1-30 keV
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11. POLARIZATION
Measured in radio. 13% average, with 30% peaks. Corrections for the rotation measure. Radial magnetic field 
Origin of radial magnetic fields, as observed in young SNRs?
X-rays (acceleration zone)
“Cleaner” information than in radio
Always radial?
Polarization percentage?
If integrated along the limb,  20% limit
Reynolds & Gilmore 2003
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12. Cas A Bright and compact. Visible through the whole band Age = 330 yr
Diameter = 5’ = 5 pc
Distance = 3.4 kpc
(BeppoSAX) Vink & Laming 2003
Hwang et al. 2004
Bright and compact. Visible through the whole band
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13. NON-THERMAL BREMSSTRAHLUNG
Interesting! It would allow direct measurements of the suprathermal electrons (injection problem)
Non-thermal X-rays dominated by synchrotron
Estimate for Cas A (Vink 2008)
Coulomb losses (net)
N-T bremsstrahlung relevant >100 keV ?
MAYBE DETECTABLE
B=300 G
net = 0,2.E9,2.E10,2.E11,2.E12
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14. 44Ti DECAY Several species of radioactive elements are produced in SNe
44Ti is characterized by a “suitable” decay time (85 yr)
Decay chain: 44Ti  44Sc  44Ca
44Sc de-excitation lines: 67.9 e 78.4 keV
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15. Simulation for Simbol-X (Renaud et al. 2008)
Total flux (67.9 and 78.4 keV) with BeppoSAX 1.51.0 x 10-4M⊙ (Vink et al. 2001). INTEGRAL confirmation
Generally lower abundances from models (e.g. Woosley & Weaver 1995, Limongi & Chieffi 2003) Explosion asymmetries are required
Simulation for Simbol-X (Renaud et al. 2008)
Direct test for asymmetric models
Lines can be resolved in various models
100 ks
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16. OTHER CANDIDATES YOUNG AND CLOSE Tycho Kepler EXTREMELY YOUNG SN 1987A
G , age 100 yr (Reynolds et al. 2008)
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17. Extremely bright in X rays
Crab Nebula
Age = 950 yr
Diameter X = 2’ = 1 pc
Distance = 2 kpc
Integrated X-ray spectrum nicely follows a power law (photon index = 2.05)
Extremely bright in X rays
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18. MODELS SPHERICAL SYMMETRY (Kennel & Coroniti 1984)
2-DIMENSIONAL RMHD NUMERICAL MODELS (e.g. Del Zanna et al. 2006)
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19. Models as a diagnostic tool
They put constraints on the wind magnetization and on its latitude dependence
(Del Zanna et al. 2006)
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20. Hard X-ray maps 1-D SCANS + MAX. ENTROPY METHOD
NHXM MAPS COULD CONSTRAIN MODELS MUCH MORE TIGHTLY
Pelling et al. 1987
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21. POLARIZATION Optical polarization Models TOROIDAL FIELD
30% in the central regions
Max 60% in a limited region
Hickson & van den Bergh 1990
Maximum allowed
for synchrotron 70%
Bucciantini et al. 2005
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22. TURBOLENT FIELD ? 100% ORDERED IN 2-D MHD MODELS
TURBULENT COMPONENT MUST BE ADDED TO PREVENT THE “LIP-SHAPING” EFFECT?
Shibata et al. 2003
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23. POLARIZATION
A turbulent component of the magnetic field would affect the maximum value of the polarization percentage.
Maximum estimated values 40% (Nakamura & Shibata 2007)
NHXM polarization maps could solve this problem
Beyond Crab very few measurable PWNe. Probably, coarse mapping of Vela.
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24. SUMMARY
Important contribution of NHXM to the understanding of several physical phenomena
What limits the energy of the accelerated electrons?
Ordered fields in the acceleration region?
Possible study of the non-thermal bremsstrahlung?
SN asymmetry from 44Ti mapping
PWNe:
Investigation of the evolution in size and morphology going from soft to harder X-rays
Polarization maps. Fraction of turbulent B?
NHXM Rome 12 / 11 / 09