A Spectroscopic Study of the Rich Supernova Remnant Population in M83 ∗

et al. 2020

ApJ

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Microquasars are neutron star or black hole X-ray binaries with jets. These jets can create shock-ionized bubbles of hot plasma that can masquerade as peculiar supernova remnants (SNRs) in extragalactic surveys. To see if this is the case in the well-studied spiral galaxy M 83, where one microquasar candidate (M 83-MQ1) has already been identified, we studied the properties of nine SNR candidates, selected because of their elongated or irregular morphology, from the set of previously identified SNRs in that galaxy. Using multiwavelength data from Chandra, the Hubble Space Telescope, Gemini, and the Australia Telescope Compact Array, we found that at least six of our nine sources are best interpreted as SNRs. For one source, we do not have enough observational data to explain its linear morphology. Another source shows a nebular optical spectrum dominated by photo-ionization by O stars, but its excess [Fe II] and radio luminosity suggest a possible hidden SNR. Finally, one source (S2) shows an elongated structure of ionized gas, two radio sources along that line, and an accretion-powered X-ray source in between them (the Chandra source L14-139). While S2 could be a chance alignment of multiple SNRs and one X-ray binary, it seems more likely that it is a single physical structure powered by the jet from the accreting compact object. In the latter case, the size and luminosity of S2 suggest a kinetic power of ∼10 40 erg s −1 , in the same class as the most powerful microquasars in the local universe (e.g., S26 in NGC 7793 and SS 433 in our own Galaxy).

Section: Optical Line Fluxes and Luminositiessupporting

confidence: 89%

A New Microquasar Candidate in M83

Soria

Blair

et al. 2020

ApJ

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“…For M83, SNR line fluxes have been measured both in narrow-band images from Magellan (Blair et al 2012) and in multi-slit spectra from Gemini-S (Winkler et al 2017). As Fig.…”

Section: Integrated Line Flux Measurements and Luminosity Comparison mentioning

confidence: 99%

“…A potential diagnostic for SNRs is to take advantage of the fact that the material behind a SNR shock will have bulk motions comparable to the local shock speed, several hundred km s −1 , whereas material in H II regions will for the most part have velocities of order 10 km s −1 . Unfortunately, although spectroscopic follow-up of a large number of the nebulae identified as SNRs in extragalactic surveys has taken place (e.g., Matonick & Fesen 1997;Blair & Long 1997;Gordon et al 1998;Lee & Lee 2014a,b;Lee et al 2015;Winkler et al 2017;Long et al 2018Long et al , 2019, most of these spectroscopic surveys have not had sufficient spectral resolution to measure the expected line broadening in SNRs and use it as a meaningful diagnostic.…”

Section: Introductionmentioning

confidence: 99%

Kinematics: A Clean Diagnostic for Separating Supernova Remnants from H ii Regions in Nearby Galaxies

Points

Winkler

et al. 2019

ApJ

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Many more supernova remnants (SNRs) are now known in external galaxies than in the Milky Way. Most of these SNRs have been identified using narrow-band imaging, separating SNRs from H II regions on the basis of [S II]:Hα ratios that are elevated compared to H II regions. However, the boundary between SNRs and H II regions is not always distinct, especially at low surface brightness. Here we explore velocity structure as a possible criterion for separating SNRs from H II regions, using a sample of well-studied SNRs in the Large Magellanic Cloud (LMC) as well as a small number of SNRs in the galaxy M83. We find, perhaps not surprisingly, that even at large diameters, SNRs exhibit velocity broadening sufficient to readily distinguish them from H II regions. We thus suggest that the purity of most extragalactic samples would be greatly improved through spectroscopic observations with a velocity resolution of order 50 km s −1 .

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confidence: 99%

“…In Table 2, we have also revised (slightly) the position and diameter for source 014, and we correct three erroneous cross references in the "Other Names" column that were discovered and corrected in the course of our work for Winkler et al (2017). Furthermore, for the convenience of future readers we include in both Tables 2 and 3 (also in the "Other Names" column) the catalog numbers from the Chandra deep X-ray survey by Long et al (2014), published after the original (2012) version of this paper.…”

mentioning

confidence: 99%

Erratum II: “The Magellan/IMACS Catalog of Optical Supernova Remnant Candidates in M83” (2012, ApJS, 203, 8; also 2013, ApJS, 207, 40)

Blair

Winkler

2017

ApJS

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Supporting material: machine-readable tables As a follow-up to the work described in our original paper, we have carried out extensive spectrophotometry of many supernova remnants (SNRs) and H II regions in M83 using Gemini-South and the GMOS instrument (Winkler et al. 2017). Comparing the derived fluxes from the spectra with our previously published and then corrected (Blair et al. 2013, hereafter Erratum I) fluxes, we have discovered an additional error beyond that described and corrected in Erratum I. This error occurred as a result of a miscommunication of the status of the flux calibration of the images when the data were being transferred between the authors. In addition, we have made additional relatively minor corrections to the flux calibration, due to adjustments from a reassessment of the transmission curves of the filters used for the observations (from IMACS on Magellan I in April 2009). As a result, the fluxes reported in the original paper, and especially those in Erratum I, are too high. This problem is most pronounced for Hα, but it also affects the reported [S II] λλ 6716, 6731 and [O III] λ 5007 line fluxes.We have corrected these calibration errors and provide revised fluxes in the versions of Tables 2 and 3 presented herein. The sense of the errors is to increase the observed [SII]:Hα ratios in the corrected data. Since this is the criterion that we use to separate H II regions from SNRs, it has only strengthened the original identifications of the SNR population in M83. Also, there are fewer SNR candidates with borderline values of this ratio.As a further confirmation of the revised flux scaling, we have compared the revised fluxes we report here not only with those determined spectroscopically by Winkler et al. 2009 -2012(Dopita et al. 2010Blair et al. 2014). Fluxes measured from all these data sets are in reasonable agreement with one another, considering the differences in instruments, filters, and widely differing image quality.