Discriminating the Progenitor Type of Supernova Remnants With Iron K-Shell Emission

Abstract

Supernova remnants (SNRs) retain crucial information about both their parent explosion and circumstellar material left behind by their progenitor. However, the complexity of the interaction between supernova ejecta and ambient medium often blurs this information, and it is not uncommon for the basic progenitor type (Ia or core-collapse) of well-studied remnants to remain uncertain. Here we present a powerful new observational diagnostic to discriminate between progenitor types and constrain the ambient medium density of SNRs using solely Fe K-shell X-ray emission. We analyze all extant Suzaku observations of SNRs and detect Fe Kα emission from 23 young or middle-aged remnants, including five first detections (IC 443, G292.0+1.8, G337.2-0.7, N49, and N63A). The Fe Kα centroids clearly separate progenitor types, with the Fe-rich ejecta in Type Ia remnants being significantly less ionized than in core-collapse SNRs. Within each progenitor group, the Fe Kα luminosity and centroid are well correlated, with more luminous objects having more highly ionized Fe. Our results indicate that there is a strong connection between explosion type and ambient medium density, and suggest that Type Ia supernova progenitors do not substantially modify their surroundings at radii of up to several parsecs. We also detect a K-shell radiative recombination continuum of Fe in W49B and IC 443, implying a strong circumstellar interaction in the early evolutionary phases of these core-collapse remnants.

The population of X-ray supernova remnants in the Large Magellanic Cloud

“…With the resolution of pn and the statistics in our hand, it is not possible to resolve the K-shell lines from various Fe ions, which will become possible with next-generation X-ray calorimeters onboard Astro-H (Takahashi et al 2012) or Athena (Barret et al 2013). Yamaguchi et al (2014) used Suzaku to systematically search for Fe K emission from Galactic and LMC SNRs. Fe Kα emission was detected in 23 SNRs, including seven remnants in the LMC.…”

“…Because the Fe K blend is a promising typing tool, we extended the search for Fe K emission of Yamaguchi et al (2014) to all LMC SNRs observed with XMM-Newton. Compared to the Suzaku sample, the coverage is more complete (i.e.…”

“…Furthermore, Yamaguchi et al (2014, their Fig. 1, right) used simple (one-dimensional) theoretical models of type Ia SNe exploding in uniform ambient media of various densities to predict the luminosity and energy of the line.…”

Supernova Remnants as Clues to Their Progenitors

“…This SNR has long been suspected to be a cavity explosion, and its bulk dynamics are hard to interpret without a fast, sustained outflow from the progenitor, with properties similar to those of accretion winds (Badenes et al, 2007;Williams et al, 2011). Yamaguchi et al (2014), plus DEM L71 (Maggi et al, 2016). The shaded regions represent theoretical predictions from Type Ia SNR models interacting with a uniform interstellar medium (Badenes et al, 2003(Badenes et al, , 2005: orange for the 56 Ni-poor delayed detonation model DDTg, blue for bright 56 Ni-rich delayed detonation model DDTa.…”

“…Patnaude et al (2015) modeled the circumstellar environments of core collapse progenitors for a range of mass loss rates and wind velocities, but did not consider Yamaguchi et al (2014). The transparent shaded regions correspond to models for either Ia or CCSNe ejecta, with yellow and light blue corresponding to the Ia models DDTa and DDTg, and red, green, magenta, and dark blue corresponding to CCSNe models SN 1987A, SN 1993J, and a 12 and 25M solar metallicity progenitor, respectively.…”