DISCOVERY OF X-RAY-EMITTING O-Ne-Mg-RICH EJECTA IN THE GALACTIC SUPERNOVA REMNANT PUPPIS A

Abstract

We report on the discovery of X-ray-emitting O-Ne-Mg-rich ejecta in the middle-aged Galactic O-rich supernova remnant Puppis A with Chandra and XMM-Newton. We use line ratios to identify a low-ionization filament running parallel to the northeastern edge of the remnant that requires supersolar abundances, particularly for O, Ne, and Mg, which we interpret to be from O-Ne-Mgrich ejecta. Abundance ratios of Ne/O, Mg/O, and Fe/O are measured to be ∼2, ∼2, and <0.3 times the solar values. Our spatially-resolved spectral analysis from the northeastern rim to the western rim otherwise reveals sub-solar abundances consistent with those in the interstellar medium. The filament is coincident with several optically emitting O-rich knots with high velocities. If these are physically related, the filament would be a peculiar fragment of ejecta. On the other hand, the morphology of the filament suggests that it may trace ejecta heated by a shock reflected strongly off the dense ambient clouds near the northeastern rim.

The most complete and detailed X-ray view of the SNR Puppis A

“…The new image of Puppis A uncovered the existence of X-ray emission in the southwest corner with the same morphological pattern of curved filaments as seen in the rest of the SNR. From this X-ray image of Puppis A we can confirm that the bluish (harder X-ray emission) central band that crosses the remnant from northeast to southwest, previously noticed by different authors (Aschenbach 1993;Hwang et al 2005;Katsuda et al 2010), extends into the newly observed southwestern region. This peculiar harder band was first attributed to absorbing material related to the Vela SNR located between us and Puppis A, which would absorb most of the soft X-ray photons (Aschenbach 1993;Hui & Becker 2006b).…”

“…After smoothing with a 10-arcsec Gaussian kernel they were combined into the three-color image of the complete remnant, as shown in Fig. 2. 1 http://cxc.harvard.edu/ciao/ The previously best combination of Puppis A images was done by Katsuda et al (2010) using six archival XMM-Newton observations and five archival Chandra observations.…”

“…Spectral X-ray studies provided evidence that the SNR shock has interacted with ambient clouds in a relatively late phase of evolution (Hwang et al 2005;Katsuda et al 2010Katsuda et al , 2012 and complementary studies (Paron et al 2008;Arendt et al 2010) indicated that the molecular cloud has already been destroyed by the shock in the BEK and that the X-ray and radio emission observed as bright features are, in fact, traces of past shock/interstellar medium (ISM) interactions. Although most of the X-ray emission is dominated by the shocked ISM, there are also isolated X-ray features rich in O, Ne, and Mg that can be identified as SN ejecta (Hwang et al 2008;Katsuda et al 2008Katsuda et al , 2010.…”

Three-dimensional neutrino-driven supernovae: Neutron star kicks, spins, and asymmetric ejection of nucleosynthesis products

“…However, diagnosing momentum asymmetries of the ejecta may be difficult except in cases where the center of mass of the gaseous SN remnant is clearly displaced relative to the NS position or where the gas cloud exhibits extreme deformation without gradients of the environmental conditions being responsible for the asymmetric ejecta expansion. The SN remnants Cassiopeia A (Isensee et al 2010;DeLaney et al 2010;Rest et al 2011;Hwang & Laming 2012) and Puppis A (Petre et al 1996;Winkler & Petre 2007;Katsuda et al 2008Katsuda et al , 2010Becker et al 2012) may be such lucky cases, because in the former all the SN ejecta in the remnant, whose mass is dominated by oxygen, while in the latter fast-moving, oxygen-rich optical filaments and knots seem to have been recoiled opposite to the direction of the high-velocity compact stellar remnant. In general, however, a major problem for observing momenta asymmetries linked to an asymmetric beginning of the explosion may result from the fact that the outgoing SN shock transfers the bulk of the explosion energy and ejecta momentum to the He and H shells, which dominate the ejecta mass in events other than stripped SNe.…”

“…In particular, it might allow one to discriminate our gravitational tug-boat mechanism from scenarios like the neutrino-driven kicks discussed by Fryer & Kusenko (2006), who expect the stronger explosion (and thus enhanced explosive nucleosynthesis) in the direction of the NS motion. High-resolution spectral investigations of young SN remnants like Puppis A (Katsuda et al 2008(Katsuda et al , 2010, G11.2-0.3 (Moon et al 2009), and Cassiopeia A (Isensee et al 2010;DeLaney et al 2010;Rest et al 2011;Hwang & Laming 2012) in different wavebands may offer a promising perspective.…”