Explosive Nucleosynthesis in Aspherical Hypernova Explosions and Late Time Spectra of Sn1998bw
نویسندگان
چکیده
Aspherical explosion models for the hypernova (hyper-energetic supernova) SN 1998bw are presented. Nucleosynthesis in aspherical explosions is examined with a two-dimensional hydrodynamical code and a detailed nuclear reaction network. Aspherical explosions lead to a strong α-rich freezeout, thus enhancing the abundance ratios [Ca, Ti, and Zn / Fe] in the ejecta. The nebular line profiles of the Fedominated blend near 5200 Å and of [O i] 6300,6363 Å are calculated and compared with the observed late time spectra of SN 1998bw. Compared with the spherical model, the unusual features of the observed nebular spectra can be better explained if SN 1998bw is a strongly aspherical explosion with a kinetic energy of ∼ 10 ergs viewed from near the jet direction. Subject headings: supernovae: individual: SN1998bw — gamma rays: bursts — nucleosynthesis — line: profiles
منابع مشابه
ar X iv : a st ro - p h / 98 07 34 5 v 1 3 1 Ju l 1 99 8 SN 1998 bw / GRB 980425 : Hypernova or Aspherical Explosion ?
The recent discovery of the unusual supernova SN1998bw and its apparent correlation with the gamma-ray burst GRB 980425 has raised new issues concerning both the GRB and SNe. SN1998bw was unusually bright at maximum light and expansion velocities were large making SN1998bw a possible candidate for a “hypernova” with explosion energies exceeding 10erg. We show that the light curve of SN1998bw ca...
متن کاملHypernova Nucleosynthesis and Galactic Chemical Evolution
We study nucleosynthesis in ’hypernovae’, i.e., supernovae with very large explosion energies ( ∼ > 10 ergs) for both spherical and aspherical explosions. The hypernova yields compared to those of ordinary corecollapse supernovae show the following characteristics: 1) Complete Siburning takes place in more extended region, so that the mass ratio between the complete and incomplete Si burning re...
متن کاملPeculiar Chemical Abundances in the Starburst Galaxy M82 and Hypernova Nucleosynthesis
X-ray observations have shown that the chemical abundance in the starburst galaxy M82 is quite rich in Si and S compared with oxygen. Such an abundance pattern cannot be explained with any combination of conventional Type I and II supernova yields. Also the energy to heavy element mass ratio of the observed hot plasma is much higher than the value resulted from normal supernovae. We calculate e...
متن کاملMULTI-DIMENSIONAL SIMULATIONS FOR EARLY PHASE SPECTRA OF ASPHERICAL HYPERNOVAE: SN 1998bw AND OFF-AXIS HYPERNOVAE
Early phase optical spectra of aspherical jet-like supernovae (SNe) are presented. We focus on energetic core-collapse SNe, or hypernovae. Based on hydrodynamic and nucleosynthetic models, radiative transfer in SN atmosphere is solved with a multi-dimensional Monte-Carlo radiative transfer code, SAMURAI. Since the luminosity is boosted in the jet direction, the temperature there is higher than ...
متن کاملAsphericity in supernova explosions from late-time spectroscopy.
Core-collapse supernovae (CC-SNe) are the explosions that announce the death of massive stars. Some CC-SNe are linked to long-duration gamma-ray bursts (GRBs) and are highly aspherical. One important question is to what extent asphericity is common to all CC-SNe. Here we present late-time spectra for a number of CC-SNe from stripped-envelope stars and use them to explore any asphericity generat...
متن کامل