Serbian Astronomical Journal 2014 Issue 189, Pages: 25-40
https://doi.org/10.2298/SAJ1489025P
Full text ( 493 KB)
Cited by
Updated radio Σ−D relation for galactic supernova remnants
Pavlović M.Z. (Faculty of Mathematics, Department of Astronomy, Belgrade)
Dobardžić A. (Faculty of Mathematics, Department of Astronomy, Belgrade)
Vukotić B. (Astronomical Observatory, Belgrade)
Urošević D. (Faculty of Mathematics, Department of Astronomy, Belgrade)
We present the updated empirical radio surface-brightness-to-diameter (Σ − D)
relation for supernova remnants (SNRs) in our Galaxy. Our original
calibration sample of Galactic SNRs with independently determined distances
(Pavlović 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 logΣ − logD plane. Non-standard orthogonal
regression keeps the Σ−D and D−Σ relations invariant within estimated
uncertainties. Our previous Monte Carlo simulations verified that the slopes
of the empirical Σ−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
(β ≈ 5.2) than the Σ−D slope in Paper I (β ≈ 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.
Keywords: ISM: supernova remnants, methods: statistical, radio continuum: ISM
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