Supernova remnants

Supernova remnants (SNR) in early stages of expansion display results of advanced (explosive) nucleosynthesis, but in later stages light up the interstellar medium by shock excitation and give information about the ISM in external galaxies complementary to that derived from H n regions. 

Fig. 3.27. Spectrum of a supernova remnant in the Scd spiral M33. Adapted from Dopita, D Odorico and Benvenuti (1980).

The evolution of a supernova remnant is believed to involve three main stages ... 

Advances in X-ray astronomy have led to good spectra of energetic objects like supernova remnants (see Fig. 3.30) and the hot gas in clusters of galaxies (see Fig. 3.31), from which some deductions about abundances can be made subject to realistic modelling, which is not always straightforward. The SNR shown in... 

Fig. 3.30. X-ray spectrum of the supernova remnant N49 in the LMC, aged between 5000 and 10 000 yr, taken with the Advanced CCD Imaging Spectrometer on board the Chandra X-ray Observatory, showing H-like and He-like K-shell lines of abundant light elements and some L-shell lines of iron, after Park et al. (2003).

Fig. 3.45. Abundances of oxygen and nitrogen in the Scd spiral M33, measured in H ii regions and supernova remnants, as a function of galactocentric distance ...

Compact central objects in supernova remnants (CCOs in SNRs)... 

Camilo, F. et al. (2002). Discovery of radio pulsations from the X-ray pulsar J0205+6449 in supernova remnant 3C58 with the Green Bank Telescope ApJ 571, L71. 

The strengths of the model are its natural connection to supemovae and star formation and that the supernova remnant would have enough time to form iron via the decay of nickel and cobalt to possibly produce the claimed iron lines. Moreover, it is expected to be a baryon-clean environment. The model is, however, very sensitive to the fine tuning of parameters. Moreover, GRB030329 places a rather strict limit of a few hours on the delay between the SN and the GRB and thus rules out the supranova model for at least this particular burst. 

The second source for which it has been claimed the detection of redshifted spectral lines is IE 1207.4-5209, a radio-quite compact star located in the center of the supernova remnant PSK 1209-51/52. IE 1207.4-5209 has been observed by the Chandra X-ray observatory. Two absorption features have been detected in the source spectrum and have been interpreted (Sanwal et al. 2002) as spectral lines associated with atomic transitions of once-ionized helium in the atmosphere of a strong magnetized (B 1.5 x 1014 G) compact star. This interpretation gives for the gravitational redshift at the star surface z = 0.12 -0.23 (Sanwal et al. 2002), which is reported in Fig. 3 and by the two dashed lines labeled z = 0.12 and z = 0.23. 

We now have clear evidence of non-thermal processes in the sky. A whole panoply of violent activities is revealed to the watchful eye of our radio. X-ray and gamma-ray telescopes. Supernova remnants, pulsars, active galactic nuclei and gamma bursts emit radiation that has clearly nothing to do with thermal activity, for their spectra bear no resemblance to those of heated bodies. 

The fact that our eyes are so exclusively tuned to the Sun has thus blinded us to almost all forms of radiation. This includes radiation from media at very different temperatures, such as the relic cosmological background that filters down to us from the beginning of time, and the great majority of non-thermal emissions, such as the signals from pulsars and supernova remnants. 

The brightest X-ray nebulas are the remnants of supernova explosions. The ejecta are thrown out so forcefully that the collision with neighbouring interstellar gases produces temperatures of several million degrees. This is sufficient to emit photons in the keV range. It is no surprise that most X-ray binaries and supernova remnants should be located in the galactic disk. 

The search for titanium-44 was undertaken by the gamma spectrometer aboard the Gamma-Ray Observatory (GRO). The 1.15 MeV line was detected in the direction of Cassiopeia A and Vela, two recent supernova remnants. Mapping the Galaxy in the 1.15 MeV line will undoubtedly be one of the main objectives of the European satellite INTEGRAL, a unique space-borne experiment in which Erance is deeply involved. ... 

The gaseous nebulas are divided up into dark nebulas, reflection nebulas, Hll regions (see below), planetary nebulas and supernova remnants. 

In this case, we must examine the effect of an asymmetrical explosion on the final result of the self-destruction of a very massive black hole, that is, the supernova remnant and black hole. Such asymmetrical supernovas may explain a fair number of gamma bursts, which have remained a deep mystery up to now. Beams and jets are more than ever in the news in astrophysics. 

The Crab Nebula is the most noticeable object in our Galaxy, and the remnant of the famous Chinese guest star appeared in 1054AD, the best association between supernova remnants(SNR) and ancient guest stars. Before seventies, the Crab Nebula was considered as a special SNR with different morphology and physical features from that of most SNRs, Now more and more Crab-like SNRs have been detected(Weiler 1985). It is necessary to make a systematical investigation for the Crab-like SNRs, especially for those with central pulsars because they offer us more physical messages than others. 

Weiler, K.W., 1985, in The Crab Nebula and Related Supernova Remnants, Kafatos, M.and Henry, R. Ed. (Cambridge Univ. Press, London)... 

X-ray emission from young, hot, shocked supernova remnants, as observed with NASA s Chandra X-Ray Observatory, confirm that core-collapse Type II supernovae are prolific nucleosynthesis sources of neon. 

The decay of 41Ca is accompanied 11% of the time by an X-ray line having energy 3.31 keV. Soalthoughitisnotaccompaniedbyagammaray, the decay may nonetheless one day be observed in a nearby supernova remnant. 

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