The Origin of the Iron-Rich Knot in Tycho's Supernova Remnant

Abstract

X-ray observations of supernova remnants (SNRs) allow us to investigate the chemical inhomogeneity of ejecta, offering unique insight into the nucleosynthesis in supernova explosions. Here we present detailed imaging and spectroscopic studies of the "Fe knot" located along the eastern rim of the Type Ia SNR Tycho (SN 1572) using Suzaku and Chandra long-exposure data. Surprisingly, the Suzaku spectrum of this knot shows no emission from Cr, Mn, or Ni, which is unusual for the Fe-rich regions in this SNR. Within the framework of the canonical delayed-detonation models for SN Ia, the observed mass ratios M_Cr/M_Fe < 0.023, M_Mn/M_Fe < 0.012, and M_Ni/M_Fe < 0.029 (at 90% confidence) can only be achieved for a peak temperature of (5.3-5.7) x 10^9 K and a neutron excess of < 2.0 x 10^-3. These constraints rule out the deep, dense core of a Chandrasekhar-mass white dwarf as the origin of the Fe knot, and favors either incomplete Si burning or the alpha-rich freeze-out regime, probably close to their boundary. An explosive He burning regime is a possible alternative, although this hypothesis is in conflict with the main properties of this SNR.

13 pages, 13 figures, accepted for publication in ApJ

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• From supernova to supernova remnant: comparison of thermonuclear explosion models
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• A Nucleosynthetic Origin for the Southwestern Fe-rich Structure in Kepler's Supernova Remnant
• Time Variability of Nonthermal X-ray Stripes in Tycho's Supernova Remnant with Chandra
• The 3-D X-ray Ejecta Structure of Tycho's Supernova Remnant
• Genus Statistic Applied to the X-ray Remnant of SN 1572: Clues to the Clumpy Ejecta Structure of Type Ia Supernovae
• RGS Observations of Ejecta Knots in Tycho's Supernova Remnant
• X-ray Study of Spatial Structures in Tycho's Supernova Remnant Using Unsupervised Deep Learning
• Discovery of Stable Titanium at the Northeastern Jet of Cassiopeia A: Need for a Weak Jet Mechanism?
• A broadband X-ray imaging spectroscopy in the 2030s: the FORCE mission
• Discovery of Year-Scale Time Variability from Thermal X-ray Emission in Tycho's Supernova Remnant
• The double detonation of a double degenerate system, from Type Ia supernova explosion to its supernova remnant