scholarly journals Is positron escape seen in the late-time light curves of Type Ia Supernovae?

1997 ◽  
Author(s):  
Peter A. Milne ◽  
Lih-Sin The ◽  
Mark D. Leising
Keyword(s):  
Light Curves ◽  
Type Ia Supernovae ◽  
Late Time ◽  
Type Ia ◽  
Ia Supernovae

scholarly journals Constraints on the density distribution of type Ia supernovae ejecta inferred from late-time light-curve flattening

2020 ◽  
Vol 493 (4) ◽  
pp. 5617-5624
Author(s):  
Doron Kushnir ◽  
Eli Waxman
Keyword(s):  
Light Curve ◽  
Weighted Average ◽  
Far Infrared ◽  
Average Density ◽  
Light Curves ◽  
Type Ia Supernovae ◽  
Late Time ◽  
Simple Method ◽  
Type Ia ◽  
Ia Supernovae

ABSTRACT The finite time, τdep, over which positrons from β+ decays of 56Co deposit energy in type Ia supernovae ejecta lead, in case the positrons are trapped, to a slower decay of the bolometric luminosity compared to an exponential decline. Significant light-curve flattening is obtained when the ejecta density drops below the value for which τdep equals the 56Co lifetime. We provide a simple method to accurately describe this ‘delayed deposition’ effect, which is straightforward to use for analysis of observed light curves. We find that the ejecta heating is dominated by delayed deposition typically from 600 to 1200 d, and only later by longer lived isotopes 57Co and 55Fe decay (assuming solar abundance). For the relatively narrow 56Ni velocity distributions of commonly studied explosion models, the modification of the light curve depends mainly on the 56Ni mass-weighted average density, 〈ρ〉t3. Accurate late-time bolometric light curves, which may be obtained with JWST far-infrared (far-IR) measurements, will thus enable to discriminate between explosion models by determining 〈ρ〉t3 (and the 57Co and 55Fe abundances). The flattening of light curves inferred from recent observations, which is uncertain due to the lack of far-IR data, is readily explained by delayed deposition in models with $\langle \rho \rangle t^{3} \approx 0.2\, \mathrm{M}_{\odot }\, (10^{4}\, \textrm{km}\, \textrm{s}^{-1})^{-3}$, and does not imply supersolar 57Co and 55Fe abundances.

scholarly journals A year-long plateau in the late-time near-infrared light curves of type Ia supernovae

2019 ◽  
Vol 4 (2) ◽  
pp. 188-195 ◽  
Author(s):  
O. Graur ◽  
K. Maguire ◽  
R. Ryan ◽  
M. Nicholl ◽  
A. Avelino ◽  
...  
Keyword(s):  
Near Infrared ◽  
Light Curves ◽  
Infrared Light ◽  
Type Ia Supernovae ◽  
Late Time ◽  
Near Infrared Light ◽  
Type Ia ◽  
Ia Supernovae

scholarly journals Gravitational Collapse versus Thermonuclear Explosion of Degenerate Stellar Cores

1994 ◽  
Vol 147 ◽  
pp. 186-213
Author(s):  
J. Isern ◽  
R. Canal
Keyword(s):  
Neutron Star ◽  
White Dwarfs ◽  
Light Curves ◽  
Type Ia Supernovae ◽  
Radioactive Elements ◽  
Border Line ◽  
Thermonuclear Explosion ◽  
Type Ia ◽  
Γ Rays ◽  
Ia Supernovae

AbstractIn this paper we review the behavior of growing stellar degenerate cores. It is shown that ONeMg white dwarfs and cold CO white dwarfs can collapse to form a neutron star. This collapse is completely silent since the total amount of radioactive elements that are expelled is very small and a burst of γ-rays is never produced. In the case of an explosion (always carbonoxygen cores), the outcome fits quite well the observed properties of Type Ia supernovae. Nevertheless, the light curves and the velocities measured at maximum are very homogeneous and the diversity introduced by igniting at different densities is not enough to account for the most extreme cases observed. It is also shown that a promising way out of this problem could be the He-induced detonation of white dwarfs with different masses. Finally, we outline that the location of the border line which separetes explosion from collapse strongly depends on the input physics adopted.

scholarly journals Late Light Curves of Type Ia SNe

2005 ◽  
Vol 192 ◽  
pp. 183-188
Author(s):  
Peter A. Milne ◽  
G.Grant Williams
Keyword(s):  
Magnetic Fields ◽  
Energy Deposition ◽  
Light Curves ◽  
Current Status ◽  
Type Ia Supernovae ◽  
Type Ia ◽  
Ia Supernovae

SummaryAt late times, the energy deposition in the ejecta of type Ia supernovae is dominated by the slowing of energetic positrons produced in 56Co → 56Fe decays. Through comparisons of simulations of energy deposition in SN Ia models with observed light curves from supernovae, we study the positron transport and thus the magnetic fields of SNe Ia. In this paper, we summarize the current status of these investigations, emphasizing the observations made of two recent SNe Ia, 1999by and 2000cx.

scholarly journals Theoretical Light Curves for Type Ia Supernovae and Determination of the Hubble Constant

1999 ◽  
Vol 183 ◽  
pp. 68-68
Author(s):  
Koichi Iwamoto ◽  
Ken'Ichi Nomoto
Keyword(s):  
Hubble Constant ◽  
Light Curves ◽  
Type Ia Supernovae ◽  
Maximum Brightness ◽  
Decline Rate ◽  
Type Ia ◽  
Error Bars ◽  
Ia Supernovae ◽  
Distance Indicators

The large luminosity (MV ≈ −19 ∼ −20) and the homogeneity in light curves and spectra of Type Ia supernovae(SNe Ia) have led to their use as distance indicators ultimately to determine the Hubble constant (H0). However, an increasing number of the observed samples from intermediate- and high-z (z ∼ 0.1 − 1) SN Ia survey projects(Hamuy et al. 1996, Perlmutter et al. 1997) have shown that there is a significant dispersion in the maximum brightness (∼ 0.4 mag) and the brighter-slower correlation between the brightness and the postmaximum decline rate, which was first pointed out by Phillips(1993). By taking the correlation into account, Hamuy et al.(1996) gave an estimate of H0 within the error bars half as much as previous ones.

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