L - D dependence for supernova remnants and its connection with the Σ- D relation

Pannuti

Duric

et al. 2005

A&A

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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.

Section: Evolutionary Tracks In the σ − D Planementioning

confidence: 52%

The $\mathsf{\Sigma}$ – Drelation for supernova remnants in nearby galaxies

Pannuti

Duric

et al. 2005

A&A

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“…so-called trivial Σ − D relation with β = 2 (Arbutina et al 2004). This can be understood mathematically from:…”

Section: The Empirical σ−D Relation For Pnementioning

confidence: 99%

The $\Sigma-{\sf \textit D}$ relation for planetary nebulae

Vukotić

Арбутина

et al. 2009

A&A

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We present an extended analysis of the relation between radio surface brightness and diameter -the so-called Σ − D relation for planetary nebulae (PNe). We revise our previous derivation of the theoretical Σ − D relation for the evolution of bremsstrahlung surface brightness in order to include the influence of the fast wind from the central star. Different theoretical forms are derived:for the first and second phases of evolution and Σ ∝ D −3 for the final stage of evolution. Also, we analyzed several different Galactic PN samples. All samples are influenced by severe selection effects, but the Malmquist bias seems to be less influential here than in the supernova remnant (SNR) samples. We derived empirical Σ − D relations for 27 sample sets using 6 updated PN papers from which an additional 21 new sets were extracted. Twenty four of these have a trivial form of β ≈ 2. However, we obtain one empirical Σ − D relation that may be useful for determining distances to PNe. This relation is obtained by extracting a recent nearby (<1 kpc) Galactic PN sample.

“…However, it still might be possible to construct the relations for some classes of SNRs. In our previous paper (Arbutina et al 2004, hereafter Paper I), we analysed the Σ– D relation(s) for remnants in a dense environment of molecular clouds. In this paper, we try to obtain a relation for SNRs evolving in interstellar media (ISMs) of lower density.…”

Section: Introductionmentioning

confidence: 99%

Σ-Drelation for supernova remnants and its dependence on the density of the interstellar medium

Арбутина

Monthly Notices of the Royal Astronomical Society

2005

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During the last couple of decades of work on the Σ–D (radio surface brightness to diameter) relation for supernova remnants (SNRs), it has been generally accepted that no single Σ–D relation can be constructed for all SNRs. However, it may still be possible to construct the relations for some classes of SNRs. In our previous paper we analysed Σ–D relation(s) for remnants in the dense environments of molecular clouds. The aim of this paper is to examine, in the same context, a class of oxygen‐rich SNRs, and to extend the analysis to remnants evolving in lower‐density interstellar media, namely Balmer‐dominated SNRs. We have obtained good relations with certain similarities to our previous findings – similarities that emphasize, again, the role of ambient density in the evolution of SNRs.