In this paper we present the updated empirical radio surface-brightness-to-diameter (Σ-D) relation for Galactic supernova remnants (SNRs) calibrated using 110 SNRs with reliable distances. We apply orthogonal fitting procedure and kernel density smoothing in Σ − D plane and compare the results with the latest theoretical Σ − D relations derived from simulations of radio evolution of SNRs. We argue that the best agreement between the empirical and simulated Σ − D relations is achieved if the mixed-morphology SNRs and SNRs of both, low brightness and small diameter, are filtered out from the calibration sample. The distances to 5 newly discovered remnants and 27 new candidates for shell SNRs are estimated from our full and filtered calibration samples.
The equipartition or minimum-energy calculation is a well-known procedure for estimating magnetic field strength and total energy in the magnetic field and cosmic ray particles by using only the radio synchrotron emission. In one of our previous papers we have offered a modified equipartition calculation for supernova remnants (SNRs) with spectral indices 0.5 < α < 1. Here we extend the analysis to SNRs with α = 0.5 and α = 1.
In this paper we present the most up-to-date list of nearby galaxies with optically detected supernova remnants (SNRs). We discuss the contribution of the Hα flux from the SNRs to the total Hα flux and its influence on derived star formation rate (SFR) for 18 galaxies in our sample. We found that the contribution of SNRs' flux to the total Hα flux is 5 ± 5%. Due to the observational selection effects, the SNRs contamination of SFRs derived herein represents only a lower limit.
We present observations of a portion of the nearby spiral galaxy IC342 using narrow band [SII] and Hα filters. These observations were carried out in November 2011 with the 2m RCC telescope at Rozhen National Astronomical Observatory in Bulgaria. In this paper we report coordinates, diameters, Hα and [SII] fluxes for 203 HII regions detected in two fields of view in IC342 galaxy. The number of detected HII regions is 5 times higher than previously known in these two parts of the galaxy.
We present detection of 67 H ii regions and two optical supernova remnant (SNR) candidates in the nearby irregular galaxy NGC 2366. The SNR candidates were detected by applying [S ii]/Hα ratio criterion to observations made with the 2-m RCC telescope at Rozhen National Astronomical Observatory in Bulgaria. In this paper we report coordinates, diameters, Hα and [S ii] fluxes for detected objects across the two fields of view in NGC 2366 galaxy. Using archival XMM-Newton observations we suggest possible X-ray counterparts of two optical SNR candidates. Also, we discard classification of two previous radio SNR candidates in this galaxy, since they appear to be background galaxies.
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