| The idea of these pages: A
major objective of NASA's Advanced Compton Telescope (ACT) is
the study of the physics of supernovae via their gamma-ray spectra.
The requirements for achieving this objective are currently being
developed. To aid this effort, we are developing these online
tools for the calculation and display of gamma-ray spectra of
supernova models. The user can choose among a menu of models,
input time(s), distance(s), and instrument characteristics (such
as sensitivity and energy resolution) and plot or output simulated
spectra. |
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Supernova Gamma-Rays
Type Ia supernovae are now routinely
used as empirically calibrated standard candles to measure distances
at redshifts of order unity. Despite this our understanding of the explosions
themselves has not progressed as rapidly. It has long been discussed
(e.g., Clayton et al.) that gamma-ray line observations offer a unique
direct view of the location and kinematics of the newly synthesized radioactivity,
and therefore, a diagnostic of the explosions. However, previous gamma-ray
spectrometers have not been sensitive enough to study SN Ia at typical
distances. Thus it is essential that the ACT sensitivity be sufficient
to detect many SN Ia with high significance.
We provide a simple way to visualize ACT observations of SN Ia using
basic instrument capabilities and current SN Ia models. We presently
use models of a Chandrasekhar mass deflagration (W7, Nomoto, Thielemann,
Yokoi 1984), a delayed detonation (DD202C, Hoflich et al. 1998), and
sub-Chandrasekhar mass explosions
(HED8, Hoflich & Khokhlov 1996). For each model we calculate the
gamma-ray spectra at times from 5--200 days post-explosion using a
modified version of the Monte Carlo transport code of The et al. (c.f.,
Milne
et al.)
The instrument capabilities are simply specified in terms of narrow line sensitivity
(3s) and energy resolution (FWHM). We assume a continuum background only, so
these two parameters define the background count rate under an instrument-resolution
line, and therefore under the broadened supernova lines. Random fluctuations
appropriate to the binning chosen are added to the spectrum. Any model at any
distance can be over-plotted as a smooth curve, to see how well the data could
discriminate among models.
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