Modified Equipartition Calculation for Supernova Remnants

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

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“…The model as- Arbutina et al 2012Arbutina et al , 2013, where we applied Eq. 13, and assumed a CR proton-toelectron number of 100:1.…”

Section: Radio Surface Brightness Evolutionmentioning

confidence: 99%

Statistical Analysis of Supernova Remnants in the Large Magellanic Cloud

Bozzetto

Filipović

Vukotić

et al. 2017

ApJS

115

158

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“…Finally, as the radio spectral index of this remnant (see Eq. 1 and Section 3) is less than the characteristic value of 0.5, we can not use the standard method, i.e., the equipartition calculation (see Arbutina et al 2012; 2013 for more details) to estimate the magnetic field strength.…”

Section: Snr Ic 443mentioning

confidence: 99%

A New Look at the Integrated Radio/Microwave Continuum Spectrum of Galactic Supernova Remnant Ic 443

Onić¹,

Urošević²,

Leahy³

2016

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Recent observations of the microwave sky, by the space telescopes such as WMAP and Planck, have opened a new window into the analysis of continuum emission from supernova remnants (SNRs). In this paper, different emission models that can explain the characteristic shape of presently known integrated radio/microwave continuum spectrum of the Galactic SNR IC 443 are tested and discussed. In particular, the possibility that the slight bump in the integrated continuum of this remnant around 20 -70 GHz is genuine and that can be explained by the contribution of additional emission mechanism such as of spinning dust is emphasized. We find that adding a spinning dust component to the emission model improves the fit of the integrated spectrum of this SNR while, at the same time preserves the physically probable parameter values. Finally, models that include the high-frequency synchrotron bending of the IC 443 radio to microwave continuum are favored.

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“…To model the radio and X-ray data, an electron spectrum with spectral index of Γ e ≈ 2.3 and a cutoff energy of E cut = 9 TeV is needed and a magnetic field strength of 100 µG. This is comparable to two different estimates: one by Völk et al (2005) of 99 +46 −26 µG, which was deduced from the thickness of the filaments in the SW region, and another one calculated by Arbutina et al (2012) of a volume-averaged magnetic field of ∼ 70 µG. The total kinetic energy of the protons above 1 GeV was found to be W p ≈ 9 × 10 49 /n cm −3 erg, which means that about 10%/n cm −3 of the supernova (Type Ia) energy has to be converted into high-energy protons.…”

Section: Discussionmentioning

confidence: 95%

Detailed spectral and morphological analysis of the shell type supernova remnant RCW 86

Abramowski

Aharonian

Benkhali

et al. 2018

A&A

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Aims. We aim for an understanding of the morphological and spectral properties of the supernova remnant RCW 86 and for insights into the production mechanism leading to the RCW 86 very high-energy γ-ray emission. Methods. We analyzed High Energy Spectroscopic System (H.E.S.S.) data that had increased sensitivity compared to the observations presented in the RCW 86 H.E.S.S. discovery publication. Studies of the morphological correlation between the 0.5 -1 keV X-ray band, the 2 -5 keV X-ray band, radio, and γ-ray emissions have been performed as well as broadband modeling of the spectral energy distribution with two different emission models. Results. We present the first conclusive evidence that the TeV γ-ray emission region is shell-like based on our morphological studies. The comparison with 2 -5 keV X-ray data reveals a correlation with the 0.4 -50 TeV γ-ray emission. The spectrum of RCW 86 is best described by a power law with an exponential cutoff at E cut = (3.5 ± 1.2 stat ) TeV and a spectral index of Γ ≈ 1.6 ± 0.2. A static leptonic one-zone model adequately describes the measured spectral energy distribution of RCW 86, with the resultant total kinetic energy of the electrons above 1 GeV being equivalent to ∼0.1% of the initial kinetic energy of a Type I a supernova explosion (10 51 erg). When using a hadronic model, a magnetic field of B ≈ 100 µG is needed to represent the measured data. Although this is comparable to formerly published estimates, a standard E −2 spectrum for the proton distribution cannot describe the γ-ray data. Instead, a spectral index of Γ p ≈ 1.7 would be required, which implies that ∼ 7 × 10 49 /n cm −3 erg has been transferred into high-energy protons with the effective density n cm −3 = n/1 cm −3 . This is about 10% of the kinetic energy of a typical Type Ia supernova under the assumption of a density of 1 cm −3 .

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Modified Equipartition Calculation for Supernova Remnants

Cited by 54 publications

References 21 publications

Statistical Analysis of Supernova Remnants in the Large Magellanic Cloud

Statistical Analysis of Supernova Remnants in the Large Magellanic Cloud

A New Look at the Integrated Radio/Microwave Continuum Spectrum of Galactic Supernova Remnant Ic 443

Detailed spectral and morphological analysis of the shell type supernova remnant RCW 86

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