Genus Statistic Applied to the X-ray Remnant of SN 1572: Clues to the Clumpy Ejecta Structure of Type Ia Supernovae. (arXiv:1903.00764v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Sato_T/0/1/0/all/0/1">Toshiki Sato</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hughes_J/0/1/0/all/0/1">John P. Hughes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Williams_B/0/1/0/all/0/1">Brian J. Williams</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Morii_M/0/1/0/all/0/1">Mikio Morii</a>
Clumpy structures are a common feature in X-ray images of young Type Ia
supernova remnants (SNRs). Although the precise origin of such clumps remains
unclear there are three generic possibilities: clumpiness imposed during the
explosion, hydrodynamic instabilities that act during the remnant’s evolution,
and pre-existing structures in the ambient medium. In this article we focus on
discriminating between clumping distributions that arise from the explosion and
those from the remnant’s evolution using existing 3D hydrodynamical
simulations. We utilize the genus statistic for this discrimination, applying
it to the simulations and {it Chandra} X-ray observations of the well-known SN
Ia remnant of SN 1572 (Tycho’s SNR). The genus curve of Tycho’s SNR strongly
indicates a skewed non-Gaussian distribution of the ejecta clumps and is
similar to the genus curve for the simulation with initially clumped ejecta. In
contrast, the simulation of perfectly smooth ejecta where clumping arises from
the action of hydrodynamic instabilities produced a genus curve that is similar
to a random Gaussian field, but disagrees strongly with the genus curve of the
observed image. Our results support a scenario in which the observed structure
of SN Ia remnants arises from initial clumpiness in the explosion.
Clumpy structures are a common feature in X-ray images of young Type Ia
supernova remnants (SNRs). Although the precise origin of such clumps remains
unclear there are three generic possibilities: clumpiness imposed during the
explosion, hydrodynamic instabilities that act during the remnant’s evolution,
and pre-existing structures in the ambient medium. In this article we focus on
discriminating between clumping distributions that arise from the explosion and
those from the remnant’s evolution using existing 3D hydrodynamical
simulations. We utilize the genus statistic for this discrimination, applying
it to the simulations and {it Chandra} X-ray observations of the well-known SN
Ia remnant of SN 1572 (Tycho’s SNR). The genus curve of Tycho’s SNR strongly
indicates a skewed non-Gaussian distribution of the ejecta clumps and is
similar to the genus curve for the simulation with initially clumped ejecta. In
contrast, the simulation of perfectly smooth ejecta where clumping arises from
the action of hydrodynamic instabilities produced a genus curve that is similar
to a random Gaussian field, but disagrees strongly with the genus curve of the
observed image. Our results support a scenario in which the observed structure
of SN Ia remnants arises from initial clumpiness in the explosion.
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