We analyse \textit{ROSAT} and \textit{Chandra} ACIS X-ray observations and HI absorption spectra of the
$γ$ Cygni supernova remnant (G78.2+2.1, DR4). The \textit{ROSAT} All-Sky-Survey image shows G78.2+2.1 has an adjacent limb-brightened shell north of it. A new \textit{ROSAT} mosaic shows details of the X-ray emission over the entire face of G78.2+2.1. We also create \textit{Chandra} mosaics which cover much of the northern rim and central regions of G78.2+2.1. HI absorption spectra result in association of G78.2+2.1 with the $γ$ Cygni nebula, with distance 1.7 to 2.6 kpc. Chandra spectra for G78.2+2.1 give an X-ray temperature of 0.6-1.2 keV (90% error), and that a Sedov model has age of 6800-10000 yr. A compact power-law X-ray source in G78.2+2.1 is consistent with the same distance as G78.2+2.1. The northern X-ray shell is identified with a B3 star at distance of 980 pc and is proposed as a stellar wind bubble.
The X-ray emission from a supernova remnant is a powerful diagnostic of the state of its shocked plasma. The temperature and the emission measure are related to the energy of the explosion, the age of the remnant, and the density of the surrounding medium. Here we present the results of a study of the remnant population of the Small Magellanic Cloud. Progress in X-ray observations of remnants has resulted in a sample of 20 remnants in the Small Magellanic Clound with measured temperatures and emission measures. We apply spherically symmetric supernova remnant evolution models to this set of re…
We present a basic model for the calculation of the luminosity distribution of supernova remnant populations. We construct theoretical Ha and joint [S II] - Ha luminosity functions for supernova remnants by combining prescriptions from a basic evolution model that provides the shock velocity and radius for SNRs of different age and pre-shock density, with shock excitation models that give the gas emissivity for shocks of different physical parameters. We assume a flat age distribution, and we explore the effect of different pre-shock density distributions or different magnetic parameters. We f…
Relations between radio surface brightness ($Σ$) and diameter ($D$) of supernova remnants (SNRs) are important in astronomy. In this paper, following the work Duric \& Seaquist (1986) at adiabatic phase, we carefully investigate shell-type supernova remnants at radiative phase, and obtain theoretical $Σ$-$D$ relation at radiative phase of shell-type supernova remnants at 1 GHz. By using these theoretical $Σ$-$D$ relations at adiabatic phase and radiative phase, we also roughly determine phases of some supernova remnant from observation data.
NGC6946 is a high star formation rate face-on spiral galaxy that has hosted ten supernovae since 1917. Not surprisingly, a large number of supernova remnants and candidates have been identified either as optical nebulae with high [S II]:H$α$ line ratios (147) or as compact non-thermal radio sources (35). However, there are only seven overlaps between these two samples. Here, we apply [Fe II] 1.644 $μ$m emission as a new diagnostic to search for supernova remnants in an attempt to resolve this discrepancy. [Fe II] is expected to be relatively strong in the radiative shocks of supernova remnants…
A revised catalogue of Galactic supernova remnants (SNRs) is presented, along with some simple statistics of their properties. Six new SNRs have been added to the catalogue since the previous published version from 2014, and six entries have been removed, as they have been identified as HII regions, leaving the number of entries in the catalogue at 294. Some simple statistics of the remnants in the catalogue, and the selection effects that apply, are discussed, along with some recently proposed Galactic SNR candidates.
We examine the evolution and emission of the supernova remnant (SNR) CTB109 using three-dimensional magnetohydrodynamics simulations. The SNR evolves in a medium divided by a plane interface into two media with different densities and pressure equilibrium. Our results reveal that a remnant with the characteristics of CTB109 is formed provided the supernova (SN) explosion takes place in the less dense medium and also if the interstellar magnetic field (ISMF) is almost uniform. Finally, we conclude that the quasiparallel mechanism can explain the brightness synchrotron emission and the position …
Core-collapse supernova remnants are the gaseous nebulae of galactic interstellar media (ISM) formed after the explosive death of massive stars. Their morphology and emission properties depend both on the surrounding circumstellar structure shaped by the stellar wind-ISM interaction of the progenitor star and on the local conditions of the ambient medium. In the warm phase of the Galactic plane (n = 1/cm3, T = 8000 K), an organised magnetic field of strength 7 microG has profound consequences on the morphology of the wind bubble of massive stars at rest. In this paper we show through 2.5D magn…
A signification fraction of Galactic massive stars (> 8Mo) are ejected from their parent cluster and supersonically sail away through the interstellar medium (ISM). The winds of these fast-moving stars blow asymmetric bubbles thus creating a circumstellar environment in which stars eventually die with a supernova explosion. The morphology of the resulting remnant is largely governed by the circumstellar medium of the defunct progenitor star. In this paper, we present 2D magneto-hydrodynamical simulations investigating the effect of the ISM magnetic field on the shape of the supernova remnants …
