A Study of Galactic Supernova Remnants, Based on Molonglo–Parkes Observational Data

Clark, David H.; Caswell, J. L.

doi:10.1093/mnras/174.2.267

Cited by 283 publications

(172 citation statements)

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“…The Ñux densities have been measured over a wide range of radio frequencies (e.g., by Kundu & Velusamy 1972 ;Dickel & DeNoyer 1975 ;Clark & Caswell 1976 ;Clark, Green, & Caswell 1975 ;Kassim 1992). The spectral index is about [0.33 (Kovalenko, PinzarÏ, & UdalÏtsov1994) to [0.4 (Giacani et al 1997, the latter reported with a Ñux density of about 400 Jy at 330 MHz.…”

Section: Distance Determinationmentioning

confidence: 99%

Modeling W44 as a Supernova Remnant in a Density Gradient with a Partially Formed Dense Shell and Thermal Conduction in the Hot Interior. I. The Analytical Model

Cox

Shelton

Maciejewski

et al. 1999

ApJ

165

222

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We show that many observations of W44, a supernova remnant in the Galactic plane at a distance of about 2500 pc, are remarkably consistent with the simplest realistic model. The model remnant is evolving in a smooth ambient medium of fairly high density, about 6 cm~3 on average, with a substantial density gradient. At the observed time it has an age of about 20,000 yr, consistent with the age of the associated pulsar, and a radius of 11È13 pc. Over most of the outer surface, radiative cooling has become important in the postshock gas ; on the denser end there has been sufficient compression of the cooled gas to develop a very thin dense half-shell of about 450 supported against further compression by M _ , nonthermal pressure. The half-shell has an expansion velocity of about 150 km s~1 and is bounded on the outer surface by a radiative shock with that speed. The deep interior of the remnant has a substantial and fairly uniform pressure, as expected from even highly idealized adiabatic models ; our model, however, is never adiabatic. Thermal conduction, while the remnant is young and hot, reduces the need for expansion cooling and prevents formation of the intensely vacuous cavity characteristic of adiabatic evolution. It radically alters the interior structure from what one might expect from familiarity with the Sedov solution. At the time of observation, the temperature in the center is about 6 ] 106 K, the density about 1 cm~3. The temperature decreases gradually away from the center, while the density rises. Farther out, where cooling is becoming important, the pressure drops precipitously, and the temperature in the denser gas there is quite low. We provide several analytic tools for the assembly of models of this type. We review the early evolution and shell formation analyses and their generalizations to evolution in a density gradient. We also calculate the density and temperature that should be present in the hot interior of a remnant with thermal conduction. We supply the van der Laan mechanism in a particularly useful form for the calculation of radio continuum from radiative remnants. Finally, we estimate the optical emission that should be present from Ñuorescence of UV light, emitted by the forming shell and the radiative shock and absorbed in the cold shell and the ambient medium, and the associated 63 km [O I] emission. Both are in agreement with the intensity and spatial structures found in recent observations. Neither requires interaction with a dense molecular cloud for its generation. We calculate the gamma rays that should be emitted by cosmic-ray electrons and ions in the shell, interacting with the cold material, and Ðnd each capable of generating about 25% of the Ñux reported by EGRET for the vicinity.

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Section: Distance Determinationmentioning

confidence: 99%

Modeling W44 as a Supernova Remnant in a Density Gradient with a Partially Formed Dense Shell and Thermal Conduction in the Hot Interior. I. The Analytical Model

Cox

Shelton

Maciejewski

et al. 1999

ApJ

165

222

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“…Various authors (e.g., Clark & Caswell 1976;Milne 1979;Caswell & Lerche 1979;Case & Bhattacharya 1998;Urošević et al 2005) have investigated this correlation. Originally applied as a tool for estimating SNR distances, it has been found to be unreliable for this purpose.…”

Section: Introductionmentioning

confidence: 99%

A statistical approach to radio emission from shell-type SNRs

Bandiera¹,

Petruk

2009

A&A

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Context. Shell-type supernova remnants (SNRs) exhibit correlations between radio surface brightness, SNR diameter, and ambient medium density, that between the first two quantities being the well known Σ-D relation. Aims. We investigate these correlations, to extract useful information about the typical evolutionary stage of radio SNRs, as well as to obtain insight into the origin of the relativistic electrons and magnetic fields responsible for the synchrotron emission observed in radio.Methods. We propose a scenario, according to which the observed correlations are the combined effect of SNRs evolving in a wide range of ambient conditions, rather than the evolutionary track of a "typical" SNR. We then develop a parametric approach to interpret the statistical data, and apply it to the data sample previously published by Berkhuijsen, as well as to a sample of SNRs in the galaxy M 33. Results. We find that SNRs cease to emit effectively in radio at a stage near the end of their Sedov evolution, and that models of synchrotron emission with constant efficiencies in particle acceleration and magnetic field amplification do not provide a close match to the data. We discuss the problem of the cumulative distribution in size, showing that the slope of this distribution does not relate to the expansion law of SNRs, as usually assumed, but only to the ambient density distribution. This solves a long-standing paradox: the almost linear cumulative distribution of SNRs led several authors to conclude that these SNRs are still in free expansion, which also implies very low ambient densities. Within this framework, we discuss the case of the starburst galaxy M 82. Conclusions. Statistical properties of SNR samples may be used to shed light on both the physics of electron acceleration and the evolution of SNRs. More precise results could be obtained by combining data of several surveys of SNRs in nearby galaxies.

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“…First, HI absorption measurements made by Dickel (1973) suggest that the remnant is probably at 3-4 kpc. The Σ − D relation, which is known to be very uncertain, suggests a distance of 3-6 kpc (Clark & Caswell 1976). Other authors have suggested that the remnant is more distant (12-14 kpc), on the basis of its optical morphology and Hα to [S II] ratio, which are more typical of older (hence larger) remnants like the Monoceros Ring (Elliott & Malin 1979;Kirshner & Winkler 1979).…”

Section: Observations and Resultsmentioning

confidence: 97%

Discovery of the young, energetic radio pulsar PSR J1105−6107

Kaspi¹,

Bailes²,

Manchester³

et al. 1997

AIP Conference Proceedings

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We report the discovery and follow-up timing observations of the 63 ms radio pulsar, PSR J1105−6107. The pulsar is young, having a characteristic age of only 63 kyr and, from its dispersion measure, is estimated to be at a distance of ∼7 kpc from the Sun. We consider its possible association with the nearby supernova remnant G290.1−0.8 (MSH 11−61A); an association requires that the pulsar's proper motion be ∼22 mas yr −1 (corresponding to ∼650 km s −1 for a distance of 7 kpc) directed away from the remnant center, assuming that the characteristic age is the true age. The pulsar's spin-down luminosity, 2.5×10 36 erg s −1 , is in the 1 Hubble Fellow 2 Current address: Kvednaberget 12, 4033 Forus, Norway -2 -top 1% of all known pulsar spin-down luminosities. Given its estimated distance, PSR J1105−6107 is therefore likely to be observable at high energies. Indeed, it is coincident with the known CGRO/EGRET source 2EG J1103−6106; we consider the possible association and conclude that it is likely.

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A Study of Galactic Supernova Remnants, Based on Molonglo–Parkes Observational Data

Cited by 283 publications

References 0 publications

Modeling W44 as a Supernova Remnant in a Density Gradient with a Partially Formed Dense Shell and Thermal Conduction in the Hot Interior. I. The Analytical Model

Modeling W44 as a Supernova Remnant in a Density Gradient with a Partially Formed Dense Shell and Thermal Conduction in the Hot Interior. I. The Analytical Model

A statistical approach to radio emission from shell-type SNRs

Discovery of the young, energetic radio pulsar PSR J1105−6107

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