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

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) NHXM Rome 12 / 11 / 09

HARD X-RAYS  YOUNG SNRs Fast shock | Powerful pulsar Cas A SN 1006 Crab Nebula NHXM Rome 12 / 11 / 09

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 NHXM Rome 12 / 11 / 09

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 NHXM Rome 12 / 11 / 09

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 NHXM Rome 12 / 11 / 09

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 NHXM Rome 12 / 11 / 09

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

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 NHXM Rome 12 / 11 / 09

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 NHXM Rome 12 / 11 / 09

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 NHXM Rome 12 / 11 / 09

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 NHXM Rome 12 / 11 / 09

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 NHXM Rome 12 / 11 / 09

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 NHXM Rome 12 / 11 / 09

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 NHXM Rome 12 / 11 / 09

OTHER CANDIDATES YOUNG AND CLOSE Tycho Kepler EXTREMELY YOUNG SN 1987A G1.9+0.3, age 100 yr (Reynolds et al. 2008) NHXM Rome 12 / 11 / 09

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 NHXM Rome 12 / 11 / 09

MODELS SPHERICAL SYMMETRY (Kennel & Coroniti 1984) 2-DIMENSIONAL RMHD NUMERICAL MODELS (e.g. Del Zanna et al. 2006) NHXM Rome 12 / 11 / 09

Models as a diagnostic tool They put constraints on the wind magnetization and on its latitude dependence (Del Zanna et al. 2006) NHXM Rome 12 / 11 / 09

Hard X-ray maps 1-D SCANS + MAX. ENTROPY METHOD NHXM MAPS COULD CONSTRAIN MODELS MUCH MORE TIGHTLY Pelling et al. 1987 NHXM Rome 12 / 11 / 09

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 NHXM Rome 12 / 11 / 09

TURBOLENT FIELD ? 100% ORDERED IN 2-D MHD MODELS TURBULENT COMPONENT MUST BE ADDED TO PREVENT THE “LIP-SHAPING” EFFECT? Shibata et al. 2003 NHXM Rome 12 / 11 / 09

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. NHXM Rome 12 / 11 / 09

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