We construct the most complete sample of supernova remnants (SNRs) in any galaxy -the Large Magellanic Cloud (LMC) SNR sample. We study their various properties such as spectral index (α), size and surface-brightness. We suggest an association between the spatial distribution, environment density of LMC SNRs and their tendency to be located around supergiant shells. We find evidence that the 16 known type Ia LMC SNRs are expanding in a lower density environment compared to the Core-Collapse (CC) type. The mean diameter of our entire population (74) is 41 pc, which is comparable to nearby galaxies. We didn't find any correlation between the type of SN explosion, ovality or age. The N (< D) relationship of a = 0.96 implies that the randomised diameters are readily mimicking such an exponent. The rate of SNe occurring in the LMC is estimated to be ∼1 per 200 yr. The mean α of the entire LMC SNR population is α=-0.52, which is typical of most SNRs. However, our estimates show a clear flattening of the synchrotron α as the remnants age. As predicted, our CC SNRs sample are significantly brighter radio emitters than the type Ia remnants. We also estimate the Σ − D relation for the LMC to have a slope ∼3.8 which is comparable with other nearby galaxies. We also find the residency time of electrons in the galaxy

Determination of the magnetic field strength in the interstellar medium is one of the most complex tasks of contemporary astrophysics. We can only estimate the order of magnitude of the magnetic field strength by using a few very limited methods. Besides Zeeman effect and Faraday rotation, the equipartition or the minimum-energy calculation is a widespread method for estimating magnetic field strength and energy contained in the magnetic field and cosmic ray particles by using only the radio synchrotron emission. Despite of its approximate character, it remains a useful tool, especially when there is no other data about the magnetic field in a source. In this paper we give a modified calculation which we think is more appropriate for estimating magnetic field strengths and energetics in supernova remnants (SNRs). Finally, we present calculated estimates of the magnetic field strengths for all Galactic SNRs for which the necessary observational data are available. The web application for calculation of the magnetic field strength of SNRs is available at

We present the updated empirical radio surface-brightness-to-diameter (? ? D) relation for supernova remnants (SNRs) in our Galaxy. Our original calibration sample of Galactic SNRs with independently determined distances (Pavlovic et al. 2013, hereafter Paper I) is reconsidered and updated with data which became available in the past two years. The orthogonal fitting procedure and probability-density-function-based (PDF) method are applied to the calibration sample in the log? ? logD plane. Non-standard orthogonal regression keeps the ??D and D?? relations invariant within estimated uncertainties. Our previous Monte Carlo simulations verified that the slopes of the empirical ??D relation should be determined by using the orthogonal regression, because of its good performances for data sets with severe scatter. The updated calibration sample contains 65 shell SNRs. 6 new Galactic SNRs are added to the sample from Paper I, one is omitted and distances are changed for 10 SNRs. The slope derived is here slightly steeper (? ? 5.2) than the ??D slope in Paper I (? ? 4.8). The PDF method relies on data points density maps which can provide more reliable calibrations that preserve more information contained in the calibration sample. We estimate distances to five new faint Galactic SNRs discovered for the first time by Canadian Galactic Plane Survey, and obtained distances of 2.3, 4.0, 1.3, 2.9 and 4.7 kiloparsecs for G108.5+11.0, G128.5+2.6, G149.5+3.2, G150.8+3.8 and G160.1?1.1, respectively. The updated empirical relation is used to estimate distances of 160 shell Galactic SNRs and new results change their distance scales up to 15 per cent, compared to the results from Paper I. The PDF calculation can provide even few times higher or lower values in comparison with the orthogonal fit, as it uses a totally different approach. However, on average, this difference is 32, 24 and 18 per cent for mode, median and mean distances. [Projekat Ministarstva nauke Republike Srbije, br. 176005: Emission nebulae: structure and evolution?. B.V. also acknowledges financial support through the Project i br. 176021: Visible and invisible matter in nearby galaxies: theory and observations]

We present the analysis of supernova remnants (SNRs) in the Large Magellanic Cloud (LMC) and their influence on the environment at far-infrared (FIR) and submillimeter wavelengths. We use new observations obtained with the Herschel Space Observatory and archival data obtained with the Spitzer Space Telescope, to make the first FIR atlas of these objects. The SNRs are not clearly discernible at FIR wavelengths, however their influence becomes apparent in maps of dust mass and dust temperature, which we constructed by fitting a modified black-body to the observed spectral energy distribution in each sightline. Most of the dust that is seen is pre-existing interstellar dust in which SNRs leave imprints. The temperature maps clearly reveal SNRs heating surrounding dust, while the mass maps indicate the removal of 3.7 +7.5 −2.5 M ⊙ of dust per SNR. This agrees with the calculations by others that significant amounts of dust are sputtered by SNRs. Under the assumption that dust is sputtered and not merely pushed away, we estimate a dust destruction rate in the LMC of 0.037 +0.075 −0.025 M ⊙ yr −1 due to SNRs, yielding an average lifetime for interstellar dust of 2 +4.0 −1.3 × 10 7 yr. We conclude that sputtering of dust by SNRs may be an important ingredient in models of galactic evolution, that supernovae may destroy more dust than they produce, and that they therefore may not be net producers of long lived dust in galaxies.

No abstract

Abstract. This paper examines relations between the radio surface brightness Σ and the diameter D (also known as Σ − D relations) for a sample of extragalactic supernova remnants (SNRs) as constructed from a combination of published data and data from our own surveys. Our sample of extragalactic SNRs is the largest ever devised for the purpose of analyzing Σ − D relations. The main results of this paper may be summarized as follows: (i) the empirical relations for SNRs in 10 of the 11 nearby galaxies studied have the approximately trivial Σ ∝ D −2 form, therefore limiting their interpretation as physically meaningful relations. In addition, these relations are subject to selection effects rendering them even less useful. Further Monte Carlo simulations suggest that the effect of survey sensitivity has the opposite effect of volume selection (e.g. Malmquist bias, a volume selection effect that shapes the Galactic sample) by tending to flatten the slopes toward a trivial relation. In this case, the true slopes may be steeper than the observed slopes; (ii) compact M 82 SNRs appear to follow a uniquely different Σ− D relation in comparison to the larger, older SNRs in the other 10 galaxies. Monte Carlo simulations suggest that the probability of this difference arising by chance is ≈1% to 10%, depending on what is assumed regarding the underlying SNR population; (iii) three candidate hypernova remnants were identified in our sample of 11 nearby galaxies.

In this paper we present new empirical radio surface brightness-to-diameter (Σ − D) relations for supernova remnants (SNRs) in our Galaxy. We also present new theoretical derivations of the Σ − D relation based on equipartition or on constant ratio between cosmic rays and magnetic field energy. A new calibration sample of 60 Galactic SNRs with independently determined distances is created. Instead of (standard) vertical regression, used in previous papers, different fitting procedures are applied to the calibration sample in the log Σ − log D plane. Non-standard regressions are used to satisfy the requirement that values of parameters obtained from the fitting of Σ − D and D − Σ relations should be invariant within estimated uncertainties. We impose symmetry between Σ − D and D − Σ due to the existence of large scatter in both D and Σ. Using four fitting methods which treat Σ and D symmetrically, different Σ − D slopes β are obtained for the calibration sample. Monte Carlo simulations verify that the slopes of the empirical Σ − D relation should be determined by using orthogonal regression, because of its good performance for data sets with severe scatter. The slope derived here (β = 4.8) is significantly steeper than those derived in previous studies. This new slope is closer to the updated theoretically predicted surface brightness-diameter slope in the radio range for the Sedov phase. We also analyze the empirical Σ − D relations for SNRs in the dense environment of molecular clouds and for SNRs evolving in lowerdensity interstellar medium. Applying the new empirical relation to estimate distances of Galactic SNRs results in a dramatically changed distance scale.

We discuss the L–D correlation (possible dependence of radio luminosity on linear diameter) for supernova remnants (SNRs) in order to see whether the Σ–D relation actually exists and whether determination of SNR distances on the basis of the Σ–D relation is possible. We do not find any significant correlation, except for the M82 starburst galaxy for which a good Σ–D relation does exist. Finally, we suggest that a similar relation might exist for Galactic SNRs associated with large molecular clouds, indicating once again that the density of the SNR environment is probably the crucial parameter in SNR evolution.