D. Dewey, V. V. Dwarkadas, F. Haberl, R. Sturm, C. R. Canizares
Deep Chandra and XMM-Newton observations show that the interaction of SN
1987A with its environment gives rise to X-ray emission from multiple
components: the HII region, the dense protrusions of the equatorial ring (ER)
including clumpy ER material, and, increasingly at later times, the
reverse-shocked supernova (SN) ejecta itself. The High Energy Transmission
Grating (HETG) observation in 1999 showed very broad lines with a full-width at
half-maximum (FWHM) of order 7000 km/s; at this time the blast wave was
primarily interacting with the H II region around the progenitor. Since then,
the X-ray emission has been increasingly dominated by narrower components as
the blast wave encounters the dense ER. Even so, a very-broad emission line
component in the grating spectra suggests that flux from the H II region is
still present. We find that deep HETG 2007 and 2011 data are better fit when of
order 20% of the flux comes from a component with FWHM around 9000 km/s. Based
on this, the observed X-ray light curves in the 0.5-2 and 3-10 keV bands are
modeled as the weighted sum of the non-equilibrium-ionization (NEI) X-ray
emission from two simple 1D hydrodynamic simulations: one for the H II region
interaction producing very-broad emission lines, and one for the dense
equatorial ring collision. Using these simple models we interpret the X-ray
emission components and their properties (e.g., abundances), predict future
light curve changes under different model assumptions, and set initial
parameters for a multi-dimensional model of SN 1987A's interaction.
View original:
http://arxiv.org/abs/1111.5314
No comments:
Post a Comment