The exceptional X-ray evolution of SN 1996cr in high resolution

Area of Science:

• * Astronomy and Astrophysics
• * High-Energy Astrophysics
• * Supernova Remnants

Background:

• * SN 1996cr is one of the nearest supernovae, offering a unique opportunity to study supernova evolution.
• * X-ray observations are crucial for probing the ejecta-circumstellar medium interaction in supernovae.

Purpose of the Study:

• * To analyze 18 years of X-ray spectral evolution of SN 1996cr.
• * To model the observed X-ray emission line profiles and understand the geometry of the interaction region.
• * To investigate the physical processes driving the supernova remnant.

Main Methods:

• * Utilized Chandra High Energy Transmission Grating Spectrometer (HETG) data from multiple epochs (2000-2018).
• * Performed spectral analysis of emission lines (Ne, Mg, Si, S, Fe) to determine plasma properties and velocities.
• * Developed and tested geometrical models, including polar configurations with varying opening angles and obscuration.

Main Results:

• * A polar geometry model with two distinct plasma components successfully reproduced observed X-ray line profiles.
• * Component 1: Cooler (≈2 keV), mildly absorbed plasma with high Ne, Mg, Si, S abundances (wide polar region, ≈58° opening angle).
• * Component 2: Hotter (≳20 keV), moderately absorbed plasma with high Fe abundances and internal obscuration (narrow polar region, ≈20° opening angle).
• * Observed trends in absorption, flux, geometry, and expansion velocity over 18 years.

Conclusions:

• * The two-component polar model provides a robust explanation for the X-ray emission from SN 1996cr.
• * The hotter and cooler components are likely associated with reflected and forward shocks, respectively.
• * The findings offer insights into plausible explosion scenarios and the physical implications of ejecta-circumstellar medium interaction.