Harvard Astronomy 201b

Supernova Remnants – in Theory and Practice

In Uncategorized on April 4, 2011 at 3:30 pm

Supernova Remnants Discussion – Important Topics

See also these handwritten notes

Stage 0: The Supernova Explosion

  • 1e53 erg carried away by neutrinos!
  • Ejecta properties: Mass ~ 1 solar mass, v ~ 10,000 km/s, Kinetic Energy ~ 1e51 erg.
  • Typical peak absolute visual magnitude ~ -18, duration ~ 3 months, energy radiated in supernova ~ 1e49 erg
  • Light curves: Type I (no hydrogen) – faster ejecta, powered by decay of radioactive Ni; Type II – slower ejecta, powered by recombination of Hydrogen
  • Primary emission mechanism – BB radiation from thermal ejecta

Stage I: The Ejecta-dominated Phase

  • Free expansion, Hubble flow model
  • Importance of B-fields, formation of shocks
  • Velocity structure of the ejecta
  • Primary emission mechanism – shocked ejecta: thermal bremsstrahlung (X-rays); shocked ISM: radio synchrotron
  • Validity – as long as Ejecta mass >> swept-up ISM mass

Stage II: The Sedov-Taylor Phase

  • Echoes of thunder
  • S-T model: validity, dimensional analysis, homologous model (blast wave position and velocity), Sedov solution (without derivation) + plots & caveats, post-shock temperature
  • Primary emission mechanism – Optical: forbidden lines ([O I], [Fe], [Mg I) ) in type I SNe; X-rays: free-free from shocked ejecta + auroral lines; Radio: synchrotron from forward shock
  • Validity – t < cooling time of ejecta, non-spherical remnants

Stage III: The Snowplow Phase

  • Radiative cooling + timescales, shell formation
  • Instabilities
  • Primary emission mechanism – Optical: forbidden lines [O III], [S II]; X-rays: free-free from shocked ISM; Radio: synchrotron from forward shock
  • Effect of internal pressure on evolution

Resources

Books:
Physical Processes in the Interstellar Medium, Lyman Spitzer, Wiley-Interscience Pub., 1978, section 10.2 (shocks) and 12.2 (supernovae).
Physics of the ISM and IGM, Bruce Draine, PUP, 2011, section 39.1

Online:
http://www.astronomy.ohio-state.edu/~ryden/ast825/ch5-6.pdf
http://wapedia.mobi/en/Supernova_remnant

Numerical Simulations of explosion:
http://qso.lanl.gov/~clf/

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