Article

# The Highly Energetic Expansion of SN2010bh Associated with GRB 100316D

[more]
(Impact Factor: 6.28). 11/2011; 753(1). DOI: 10.1088/0004-637X/753/1/67
Source: arXiv

ABSTRACT We present the spectroscopic and photometric evolution of the nearby (z =
0.059) spectroscopically confirmed type Ic supernova, SN 2010bh, associated
with the soft, long-duration gamma-ray burst (X-ray flash) GRB 100316D.
Intensive follow-up observations of SN 2010bh were performed at the ESO Very
Large Telescope (VLT) using the X-shooter and FORS2 instruments. Owing to the
detailed temporal coverage and the extended wavelength range (3000--24800 A),
we obtained an unprecedentedly rich spectral sequence among the hypernovae,
making SN 2010bh one of the best studied representatives of this SN class. We
find that SN 2010bh has a more rapid rise to maximum brightness (8.0 +/- 1.0
rest-frame days) and a fainter absolute peak luminosity (L_bol~3e42 erg/s) than
previously observed SN events associated with GRBs. Our estimate of the ejected
(56)Ni mass is 0.12 +/- 0.02 Msun. From the broad spectral features we measure
expansion velocities up to 47,000 km/s, higher than those of SNe 1998bw (GRB
980425) and 2006aj (GRB 060218). Helium absorption lines He I lambda5876 and He
I 1.083 microm, blueshifted by ~20,000--30,000 km/s and ~28,000--38,000 km/s,
respectively, may be present in the optical spectra. However, the lack of
coverage of the He I 2.058 microm line prevents us from confirming such
identifications. The nebular spectrum, taken at ~186 days after the explosion,
shows a broad but faint [O I] emission at 6340 A. The light-curve shape and
photospheric expansion velocities of SN 2010bh suggest that we witnessed a
highly energetic explosion with a small ejected mass (E_k ~ 1e52 erg and M_ej ~
3 Msun). The observed properties of SN 2010bh further extend the heterogeneity
of the class of GRB supernovae.

1 Follower
·
194 Views
• ##### Article: OPTICAL OBSERVATIONS OF THE TYPE Ic SUPERNOVA 2007gr IN NGC 1058
[Hide abstract]
ABSTRACT: We present extensive optical observations of the normal Type Ic supernova (SN) 2007gr, spanning from about one week before maximum light to more than one year thereafter. The optical light and color curves of SN 2007gr are very similar to those of the broad-lined Type Ic SN 2002ap, but the spectra show remarkable differences. The optical spectra of SN 2007gr are characterized by unusually narrow lines, prominent carbon lines, and slow evolution of the line velocity after maximum light. The earliest spectrum (taken at t = –8 days) shows a possible signature of helium (He I λ5876 at a velocity of ~19,000 km s–1). Moreover, the larger intensity ratio of the [O I] λ6300 and λ6364 lines inferred from the early nebular spectra implies a lower opacity of the ejecta shortly after the explosion. These results indicate that SN 2007gr perhaps underwent a less energetic explosion of a smaller-mass Wolf-Rayet star (~8-9 M ☉) in a binary system, as favored by an analysis of the progenitor environment through pre-explosion and post-explosion Hubble Space Telescope images. In the nebular spectra, asymmetric double-peaked profiles can be seen in the [O I] λ6300 and Mg I] λ4571 lines. We suggest that the two peaks are contributed by the blueshifted and rest-frame components. The similarity in velocity structure and the different evolution of the strength of the two components favor an aspherical explosion with the ejecta distributed in a torus or disk-like geometry, but inside the ejecta the O and Mg have different distributions.
The Astrophysical Journal 07/2014; 790(2):120. DOI:10.1088/0004-637X/790/2/120 · 6.28 Impact Factor
• Source
##### Article: A search for Fermi bursts associated with supernovae and their frequency of occurrence
[Hide abstract]
ABSTRACT: Context: Observations suggest that the major fraction of long duration gamma-ray bursts (GRBs) are connected with broad-lines supernovae Ib/c, (SNe-Ibc). The presence of GRB-SNe is revealed by rebrightenings emerging from the optical GRB afterglow $10$--$15$ days, in the rest-frame of the source, after the prompt GRB emission. Aims: \textit{Fermi}-GBM has a field of view (FoV) which is about 6.5 times larger than the FoV of \textit{Swift}, therefore we expect that a number of GRB-SN connections have been missed due to lack of optical and X-ray instruments on board of \textit{Fermi}, which are essential to reveal SNe associated with GRBs. This fact has motivated our search in the \textit{Fermi} catalogue for possible GRB-SN events. Methods: The search for possible GRB-SN associations follows two requirements: (1) SN should fall inside the \textit{Fermi}-GBM error box of the considered long GRB, and (2) this GRB should occur within $20$ days before the SN event. Results: We have found $5$ cases, within $z<0.2$ fulfilling the above reported requirements. One of them, GRB 130702A-SN 2013dx, was already known as GRB-SN association. We have analyzed the remaining $4$ cases and we concluded that three of them are, very likely, just random coincidences, due to the \textit{Fermi}-GBM large error box associated with each GRB detection. We found one GRB possibly associated with a SN 1998bw-like, GRB 120121B/SN 2012ba. Conclusions: The very low redshift of GRB 120121B/SN 2012ba ($z = 0.017$) implies a low isotropic energy of this burst ($E_{iso} = 1.39 \times 10^{48}$) erg. We then compute the rate of \textit{Fermi} low-luminosity GRBs connected with SNe to be $\rho_{0,b} \leq 770\$Gpc$^{-3}$yr$^{-1}$. We estimate that \textit{Fermi}-GBM could detect $1$--$4$ GRBs-SNe within $z \leq 0.2$ in the next 4 years.
Astronomy and Astrophysics 08/2014; 569. DOI:10.1051/0004-6361/201424700 · 4.48 Impact Factor
• Source
##### Article: DEFINING PHOTOMETRIC PECULIAR TYPE Ia SUPERNOVAE
[Hide abstract]
ABSTRACT: We present a new photometric identification technique for SN 1991bg-like type Ia supernovae (SNe Ia), i.e. objects with light-curve characteristics such as later primary maxima and absence of secondary peak in redder filters. This method is capable of selecting out this sub-group from the normal type Ia population. Furthermore, we find that recently identified peculiar sub-types such as SNe Iax and super-Chandrasekhar SNe Ia have similar photometric characteristics as 91bg-like SNe Ia, namely the absence of secondary maxima and shoulders at longer wavelengths, and can also be classified with our technique. The similarity of these different SN Ia sub-groups perhaps suggests common physical conditions. This typing methodology permits the photometric identification of pe-culiar SNe Ia in large up-coming wide field surveys either to study them further or to obtain a pure sample of normal SNe Ia for cosmological studies. Subject headings: supernovae: general
The Astrophysical Journal 09/2014; 795(2). DOI:10.1088/0004-637X/795/2/142 · 6.28 Impact Factor