1 / 34

Dejan Uro š evi ć Department of Astronomy, Faculty of Mathematics, University of Belgrade

Dejan Uro š evi ć Department of Astronomy, Faculty of Mathematics, University of Belgrade. Supernova remnants: evolution, statistics, spectra. Hydrodynamic Evolution of SNRs.

doris-barber
Télécharger la présentation

Dejan Uro š evi ć Department of Astronomy, Faculty of Mathematics, University of Belgrade

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Dejan Urošević Department of Astronomy, Faculty of Mathematics, University of Belgrade Supernova remnants: evolution, statistics, spectra

  2. Hydrodynamic Evolution of SNRs • First phase – free expansion phase (Ms < Me), till 3/4Ek → U (Ms 3Me), (for 1/2Ek → U, Ms  Me). • Second phase – adiabatic phase (Ms >> Me ) till 1/2Ek → radiation • Third phase – isothermal phase – formation of thick shell • Forth phase – dissipation into ISM

  3. Radio Brightness Evolution in the Adiabatic Phase • synchrotron emissivity  K H1+ -, where K from N(E)=KE1+2 and spectral index  from S - • surface brightness = S/ =Vshell/D22, where D is SNR diameter

  4. magnetic field H = f1(D) andK = f2(D); both functions are power low functions • surface brightness becomes:  Dfk() DfH() Vshell/D2 • finally we obtain so-called- D relation: = AD-, where =-(fk() +fH()+1) and A=const.

  5. Trivial Theoretical - D Relation • if the luminosity is constant (or independent on D) during SNR expansion we have:  D-2 • this is trivial form of the theoretical - D relation

  6. Short History of the Theoretical - D relation • Shklovsky (1960) - spherical model with: H  D-2, =0.5   D-6 • Lequeux (1962) - shell model with: H  D-2, =0.5   D-5.8

  7. Poveda & Woltjer (1968) - using van der Laan (1962) model with: H = const.,=0.5   D-3 • Kesteven (1968) - shell of constant thickness: H  D-1,=0.5   D-4.5

  8. Duric & Seaquist (1986) - for H  D-2, =0.5   D-3.5 (D>>1pc),  D-5 (D<<1pc) - for =0.5 and 1.5  x  2   D-(2.75    3.5) (D>>1pc) • Berezhko & Volk (2004)  D-4.25(time-dependent nonlinear kinetic theory)

  9. STATISTICS OF SNRs

  10. Empirical -D Relation • Necessary for determination of distances to Galactic SNRs identified only in radio continuum • Necessary for confirmation of the theory in order to define valid evolutionary tracks

  11. Empirical -D Relations (Related Problems) • Critical analyses: Green (1984, 1991, 2004) • Galactic sample - distances determination problem - Malmquist Bias - volume selection effect - other selection effects (sensitivity, resolution, confusion)

  12. Extragalactic samples - sensitivity (surface brightness () limits) - resolution (angular-size () limits) - confusion

  13. Updated Empirical - D Relations • Galactic relation (Milky Way (MW) 36 SNRs)  D-2.4(Case & Bhattacharya 1998)

  14. Extragalactic sample (11 galaxies) LMC, SMC, M31, M33, IC1613, NGC300, NGC6946, NGC7793, M82, NGC1569, NGC2146 (148 SNRs) - Monte Carlo simulations suggest that the effect of survey sensitivity tending to flatten the slopes toward the trivial relation (opposite to effect of Malmquist bias) (Urošević et al. 2005)

  15. the only one valid empirical -D relation is constructed for M82 (21 SNRs):  D-3.4, the validity was checked by Monte Carlo simulations and by L-D (luminosity-diameter) dependences (Urošević et al. 2005, Arbutina et al. 2004) - also, this relation is appropriate for determination of distances to SNRs (Arbutina et al. 2004)

  16. Synchrotron spectra

  17. Thermal Emission from SNRs • Thermal Bremsstrahlung  N2 T-1/2, where Nis particle concentration and T is temperature

  18. There are two rare types of SNRs with strong thermal emission (Urošević and Pannuti 2005)

  19. the first type – the relatively young SNRs in the adiabatic phase of evolution that evolve in the dense molecular cloud (MC) – D  20 pc, 1GHz ~ 10-20 (SI) – for N 300 cm-3 and T ~ 106 K  1GHz, therm.1GHz, synch.

  20. the second type – the extremely evolved SNRs in the late adiabatic phase expanded in denser warm medium – D  200 pc, 1GHz ~ 10-22 (SI) – for N 1 - 10 cm-3 and T ~ 104 K  1GHz, therm.(0.1 - 10)1GHz, synch.

  21. HB3 Urošević et al. 2007

  22. HB3 – observational data • S1GHz = 50 Jy • D= 70 pc (for distance of 2 kpc) • Shell thickness = 0.05 D ↓ ↓ ↓ • Emissivity 1GHz=1.67 x 10-37 (ergs sec-1 cm-3 Hz-1)

  23. HB3 - density of environment We recall (cgs)= 7x10-38 N2 T-1/2 if we suppose 104 < T < 106 K ↓ ↓ ↓ 10 < ne < 35 cm-3

  24. SUMMARY • Some updated results related to: - evolution - statistic - spectra of SNRs are given.

  25. THANK YOU VERY MUCH ON YOUR PATIENT!!!

More Related