Supernova remnants in M33: X-ray properties as observed by XMM–Newton

Abstract

We have carried out a study of the X-ray properties of the supernova remnant (SNR) population in M33 with XMM-Newton, comprising deep observations of 8 fields in M33 covering all of the area within the D 25 contours, and with a typical luminosity of 7.1×10 34 erg s −1 (0.2-2.0 keV) . Here we report our work to characterize the X-ray properties of the previously identified SNRs in M33, as well as our search for new X-ray detected SNRs. With our deep observations and large field of view we have detected 105 SNRs at the 3σ level, of which 54 SNRs are newly detected in X-rays, and three are newly discovered SNRs. Combining XMM-Newton data with deep Chandra survey data allows detailed spectral fitting of 15 SNRs, for which we have measured temperatures, ionization timescales, and individual abundances. This large sample of SNRs allows us to construct an X-ray luminosity function, and compare its shape to luminosity functions from host galaxies of differing metallicities and star formation rates to look for environmental effects on SNR properties. We conclude that while metallicity may play a role in SNR population characteristics, differing star formation histories on short timescales, and small-scale environmental effects appear to cause more significant differences between X-ray luminosity distributions. In addition, we analyze the X-ray detectability of SNRs, and find that in M33 SNRs with higher [SII]/Hα ratios, as well as those with smaller galactocentric distances, are more detectable in X-rays.

Formation time-scales for high-mass X-ray binaries in M33

“…For sources with Spitzer counterparts (65 sources) the categorization as SNR or foreground star was strengthened if the Spitzer colors were ≤ 0. Foreground stars can sometimes be identified by visual inspection, and SNRs were likewise easily identified via cross-correlation with the SNR catalogs of Long et al (2010) and Garofali et al (2017).…”

MMT Spectroscopy of Supernova Remnant Candidates in M33

“…1. Recently, Garofali et al (2017) have compiled their own list of SNRs from Long10 and LL14 and elsewhere. Their list has 218 objects, three of which-XMM-081, XMM-089, and XMM-095-were not identified either by Long10 or LL14, and which based on our inspection of the LGGS images have no associated optical counterparts.…”

The Morphologies and Kinematics of Supernova Remnants

“…Young, nearby supernova remnants (SNRs) offer the means to study SN explosions and dynamics at sub-pc scales, and thus they are crucial to test the predictions of SN models. Evolved SNRs are observable for up to 10 5 years after the explosions across the electromagnetic spectrum, and multiwavelength campaigns have identified over 500 SNRs in the Milky Way and nearby galaxies (Badenes et al 2010, Sasaki et al 2012, Green 2014, Maggi et al 2016, Garofali et al 2017. Detailed investigations of SNRs that are a few thousand years old or less have yielded valuable insights into the progenitors, environments, and explosion dynamics for all SN subtypes (see e.g., Vink 2012 for a review).…”