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Register a new userModels for the Type Ic Hypernova SN 2003lw associated with GRB 031203
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The Gamma-Ray Burst 031203 at a redshift z=0.1055 revealed a highly reddened Type Ic Supernova, SN 2003lw, in its afterglow light. This is the third well established case of a link between a long-duration GRB and a type Ic SN. The SN light curve is obtained subtracting the galaxy contribution and is modelled together with two spectra at near-maximum epochs. A red VLT grism 150I spectrum of the SN near peak is used to extend the spectral coverage, and in particular to constrain the uncertain reddening, the most likely value for which is E_{G+H}(B-V) about 1.07 +/- 0.05. Accounting for reddening, SN 2003lw is about 0.3 mag brighter than the prototypical GRB-SN 1998bw. Light curve models yield a 56Ni mass of about 0.55 solar mass. The optimal explosion model is somewhat more massive (ejecta mass about 13 solar mass) and energetic (kinetic energy about 6 times 10^52 erg) than the model for SN 1998bw, implying a massive progenitor (40 - 50 solar mass). The mass at high velocity is not very large (1.4 solar mass above 30000 km/s, but only 0.1 solar mass above 60000 km/s), but is sufficient to cause the observed broad lines. The similarity of SNe 2003lw and 1998bw and the weakness of their related GRBs, GRB031203 and GRB980425, suggest that both GRBs may be normal events viewed slightly off-axis or a weaker but possibly more frequent type of GRB.
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Photometric and spectroscopic data of the energetic Type Ic supernova (SN) 2002ap are presented, and the properties of the SN are investigated through models of its spectral evolution and its light curve. The SN is spectroscopically similar to the hypernova SN 1997ef. However, its kinetic energy [$sim (4-10) times 10^{51}$ erg] and the mass ejected (2.5-5 $M_{odot}$) are smaller, resulting in a faster-evolving light curve. The SN synthesized $sim 0.07 M_{odot}$ of $^{56}$Ni, and its peak luminosity was similar to that of normal SNe. Brightness alone should not be used to define a hypernova, whose defining character, namely very broad spectral features, is the result of a high kinetic energy. The likely main-sequence mass of the progenitor star was 20-25 $M_{odot}$, which is also lower than that of both hypernovae SNe 1997ef and 1998bw. SN 2002ap appears to lie at the low-energy and low-mass end of the hypernova sequence as it is known so far. Observations of the nebular spectrum, which is expected to dominate by summer 2002, are necessary to confirm these values.
The X-Ray Flash (XRF), 031203 with a host galaxy at z=0.1055, is, apart from GRB980425, the closest Gamma-Ray Burst (GRB) or XRF known to date. We monitored its host galaxy from 1-100 days after the burst. In spite of the high extinction to the source and the bright host, a significant increase and subsequent decrease has been detected in the apparent brightness of the host, peaking between 10 and 33 days after the GRB. The only convincing explanation is a supernova (SN) associated with the XRF, SN2003lw. This is the earliest time at which a SN signal is clearly discernible in a GRB/XRF (apart from SN1998bw). SN2003lw is extremely luminous with a broad peak and can be approximately represented by the lightcurve of SN1998bw brightened by ~0.55 mag, implying a hypernova, as observed in most GRB-SNe. The XRF-SN association firmly links XRFs with the deaths of massive stars and further strengthens their connection with GRBs. The fact that SNe are also associated with XRFs implies that Swift may detect a significant population of intermediate redshift SNe very soon after the SN explosions, a sample ideally suited for detailed studies of early SN physics.
Spectroscopic and spectropolarimetric observations of SN 2003dh/GRB 030329 obtained in 2003 May using the Subaru 8.2 m telescope are presented. The properties of the SN are investigated through a comparison with spectra of the Type Ic hypernovae SNe 1997ef and 1998bw. (Hypernovae being a tentatively defined class of SNe with very broad absorption features: these features suggest a large velocity of the ejected material and possibly a large explosion kinetic energy.) Comparison with spectra of other hypernovae shows that the spectrum of SN 2003dh obtained on 2003 May 8 and 9, i.e., 34-35 rest-frame days after the GRB (for z=0.1685), are similar to those of SN 1997ef obtained ~34-42 days after the fiducial time of explosion of that SN. The match with SN 1998bw spectra is not as good (at rest 7300-8000 A, but again spectra obtained ~33-43 days after GRB 980425 are preferred. This indicates that the SN may have intermediate properties between SNe 1997ef and 1998bw. Based on the analogy with the other hypernovae, the time of explosion of SN 2003dh is then constrained to be between -8 and +2 days of the GRB. The Si and O P-Cygni lines of SN 2003dh seem comparable to those of SN 1997ef, which suggests that the ejected mass in SN 2003dh may match that in SN 1997ef. Polarization was marginally detected at optical wavelengths. This is consistent with measurements of the late afterglow, implying that it mostly originated in the interstellar medium of the host galaxy.
We here report a spectroscopic monitor for the supernova SN,2017iuk associated with the long-duration low-luminosity gamma-ray burst GRB,171205A at a redshift of 0.037, which is up to now the third GRB-SN event away from us. Our spectroscopic observations and spectral analysis allow us to identify SN,2017iuk as a typical broad-line type Ic SN. A comparison study suggests that the type-IcBL SN,2017iuk resembles to SN,2006aj in following aspects: 1) similar spectra at the nearby epochs, 2) comparable evolution of the photospheric velocity obtained from the measurements based on both ion{Si}{2}$lambda$6355 line and spectral modeling, and 3) comparable explosion parameters. This analogy could imply a formation of a neutron star in the core-collapse of GRB,171205A/SN,2017iuk as previously suggested in GRB,060218/SN,2006aj. The properties of the host galaxy is discussed, which suggests that GRB,171205A/SN,2017iuk occurred in an early type (S0), high-mass, starforming galaxy with low specific SFR and solar metallicity.
The properties of the bright and energetic Type Ic SN 1997ef are investigated using a Monte Carlo spectrum synthesis code. Analysis of the earliest spectra is used to determine the time of outburst. The changing features of the spectrum and the light curve are used to probe the ejecta and to determine their composition, verifying the results of explosion calculations. Since synthetic spectra computed using our best explosion model CO100 are only moderately good reproductions of the observations, the inverse approach is adopted, and a density structure is derived by demanding that it gives the best possible fit to the observed spectrum at every epoch analysed. It is found that the density structure of model CO100 is adequate at intermediate velocities (5000--25000 km/s), but that a slower density decline ($rho propto r^{-4}$) is required to obtain the extensive line blending at high velocities (25000--50000 km/s). The `best fit density distribution results in somewhat different parameters for the SN, namely an ejecta mass of 9.6$M_odot$ and an explosion kinetic energy of 1.75 x 10^{52} erg. The modified density structure is used to compute a synthetic light curve, which is found to agree very well with the observed bolometric light curve around maximum. The amount of radioactive $^{56}$Ni produced by the SN is confirmed at 0.13$M_odot$. In the context of an axisymmetric explosion, a somewhat smaller kinetic energy than that of SN 1998bw may have resulted from the non alignment of the symmetry axis of the SN and the line of sight. This might also explain the lack of evidence for a Gamma Ray Burst correlated with SN 1997ef.
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