| 1. |
- Maeda, Keiichi, et al.
(författare)
-
Effects of the explosion asymmetry and viewing angle on the Type Ia supernova colour and luminosity calibration
- 2011
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 413:4, s. 3075-3094
-
Forskningsöversikt (refereegranskat)abstract
- Phenomenological relations exist between the peak luminosity and other observables of type Ia supernovae (SNe Ia) that allow one to standardize their peak luminosities. However, several issues are yet to be clarified: SNe Ia show colour variations after the standardization. Also, individual SNe Ia can show residuals in their standardized peak absolute magnitude at the level of similar to 0.15 mag. In this paper, we explore how the colour and luminosity residual are related to the wavelength shift of nebular emission lines observed at greater than or similar to 150 d after the maximum light. A sample of 11 SNe Ia which likely suffer from little host extinction indicates a correlation (3.3 Sigma) between the peak B - V colour and the late-time emission-line shift. Furthermore, a nearly identical relation applies for a larger sample in which only three SNe with B - V greater than or similar to 0.2 mag are excluded. Following the interpretation that the late-time emission-line shift is a tracer of the viewing direction from which an off-centre explosion is observed, we suggest that the viewing direction is a dominant factor controlling the SN colour and that a large part of the colour variations is intrinsic, rather than due to the host extinction. We also investigate a relation between the peak luminosity residuals and the wavelength shift in nebular emission lines in a sample of 20 SNe. We thereby found a hint of a correlation (at similar to 1.6 Sigma level). The confirmation of this will require a future sample of SNe with more accurate distance estimates. Radiation transfer simulations for a toy explosion model where different viewing angles cause the late-time emission-line shift are presented, predicting a strong correlation between the colour and shift, and a weaker one for the luminosity residual.
|
|
| 2. |
- Pignata, Giuliano, et al.
(författare)
-
SN 2009bb : A PECULIAR BROAD-LINED TYPE Ic SUPERNOVA
- 2011
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 728:1, s. 14-
-
Tidskriftsartikel (refereegranskat)abstract
- Ultraviolet, optical, and near-infrared photometry and optical spectroscopy of the broad-lined Type Ic supernova (SN) 2009bb are presented, following the flux evolution from -10 to +285 days past B-band maximum. Thanks to the very early discovery, it is possible to place tight constraints on the SN explosion epoch. The expansion velocities measured from near maximum spectra are found to be only slightly smaller than those measured from spectra of the prototype broad-lined SN 1998bw associated with GRB 980425. Fitting an analytical model to the pseudobolometric light curve of SN 2009bb suggests that 4.1 +/- 1.9M(circle dot) of material was ejected with 0.22 +/- 0.06 M(circle dot) of it being (56)Ni. The resulting kinetic energy is 1.8 +/- 0.7 x 10(52) erg. This, together with an absolute peak magnitude of M(B) = -18.36 +/- 0.44, places SN 2009bb on the energetic and luminous end of the broad-lined Type Ic (SN Ic) sequence. Detection of helium in the early time optical spectra accompanied with strong radio emission and high metallicity of its environment makes SN 2009bb a peculiar object. Similar to the case for gamma-ray bursts (GRBs), we find that the bulk explosion parameters of SN 2009bb cannot account for the copious energy coupled to relativistic ejecta, and conclude that another energy reservoir (a central engine) is required to power the radio emission. Nevertheless, the analysis of the SN 2009bb nebular spectrum suggests that the failed GRB detection is not imputable to a large angle between the line-of-sight and the GRB beamed radiation. Therefore, if a GRB was produced during the SN 2009bb explosion, it was below the threshold of the current generation of gamma-ray instruments.
|
|
| 3. |
- Stritzinger, Maximilian, et al.
(författare)
-
THE CARNEGIE SUPERNOVA PROJECT : SECOND PHOTOMETRY DATA RELEASE OF LOW-REDSHIFT TYPE Ia SUPERNOVAE
- 2011
-
Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 142:5, s. 156-
-
Tidskriftsartikel (refereegranskat)abstract
- The Carnegie Supernova Project (CSP) was a five-year observational survey conducted at Las Campanas Observatory that obtained, among other things, high-quality light curves of similar to 100 low-redshift Type Ia supernovae (SNe Ia). Presented here is the second data release of nearby SN Ia photometry consisting of 50 objects, with a subset of 45 having near-infrared follow-up observations. Thirty-three objects have optical pre-maximum coverage with a subset of 15 beginning at least five days before maximum light. In the near-infrared, 27 objects have coverage beginning before the epoch of B-band maximum, with a subset of 13 beginning at least five days before maximum. In addition, we present results of a photometric calibration program to measure the CSP optical (uBgVri) bandpasses with an accuracy of similar to 1%. Finally, we report the discovery of a second SN Ia, SN 2006ot, similar in its characteristics to the peculiar SN 2006bt.
|
|
