Low-frequency radio maps and spectra of supernova remnants

Dickel, J. R.; Denoyer, L. K.

doi:10.1086/111760

Cited by 29 publications

(21 citation statements)

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“…Xiao & Zhu (2012) showed that the radio spectral index (α) of the remnant is about −0.41, derived from 21 cm, 11 cm, and 6 cm radio continuum data, which is generally consistent with the result of previous works (Dickel & Denoyer 1975;Graham et al 1982). Throughout this paper, all directions are described in Galactic coordinates to match the MWISP CO survey.…”

Section: Snr G2055+05 (Monoceros Nebula)supporting

confidence: 88%

Molecular Environments of Three Large Supernova Remnants in the Third Galactic Quadrant: G205.5+0.5, G206.9+2.3, and G213.0–0.6

Zhou

Yang

et al. 2017

ApJ

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We present CO observations toward three large supernova remnants (SNRs) in the third Galactic quadrant using the Purple Mountain Observatory Delingha 13.7 m millimeter-wavelength telescope. The observations are part of the high-resolution CO survey of the Galactic plane between Galactic longitudes l = −10• to 250• and latitudes b = −5• to 5• . CO emission was detected toward the three SNRs: G205.5+0.5 (Monoceros Nebula), G206.9+2.3 (PKS 0646+06), and G213.0−0.6. Both of SNRs G205.5+0.5 and G213.0−0.6 exhibit the morphological agreement (or spatial correspondences) between the remnant and the surrounding molecular clouds (MCs), as well as kinematic signatures of shock perturbation in the molecular gas. We confirm that the two SNRs are physically associated with their ambient MCs and the shock of SNRs is interacting with the dense, clumpy molecular gas. SNR G206.9+2.3, which is close to the northeastern edge of the Monoceros Nebula, displays the spatial coincidence with molecular partial shell structures at V LSR ∼ 15 km s −1 . While no significant line broadening has been detected within or near the remnant, the strong morphological correspondence between the SNR and the molecular cavity implies that SNR G206.9+2.3 is probably associated with the CO gas and is evolving in the low-density environment. The physical features of individual SNRs, together with the relationship between SNRs and their nearby objects, are also discussed.

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Section: Snr G2055+05 (Monoceros Nebula)supporting

confidence: 88%

Molecular Environments of Three Large Supernova Remnants in the Third Galactic Quadrant: G205.5+0.5, G206.9+2.3, and G213.0–0.6

Zhou

Yang

et al. 2017

ApJ

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“…G192.8−1.1 is not a SNR G192.8−1.1 (PKS 0607+17) has been proposed as a SNR with an angular extent of about 80 (Milne & Hill 1969;Caswell 1970). The non-thermal spectral index derived was α ∼ −0.5 (Milne & Dickel 1974;Dickel & Denoyer 1975). Berkhuijsen (1974) suggested that G192.8−1.1 is a small part of an even larger SNR, which she called the "Origem Loop" with a diameter of about 5 • , but later Caswell (1985) performed high angular resolution (∼1 ) observations at λ21 cm using the DRAO synthesis telescopes and argued again that G192.8−1.1 is a discrete SNR with a radio spectral index of α ∼ −0.55.…”

Section: Resultsmentioning

confidence: 99%

“…On the basis of the radio absorption, he also argued that the SNR is situated behind the H ii region. The SNR was studied at low and intermediate radio frequencies by Holden (1968), Milne & Hill (1969), and Dickel & Denoyer (1975). The radio structures are quite complicated in this region.…”

Section: G2055+05 (Monoceros Nebula)mentioning

confidence: 99%

A Sino-Germanλ6 cm polarization survey of the Galactic plane

Gao

Han

Reich

et al. 2011

A&A

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Context.Observations of large supernova remnants (SNRs) at high frequencies are rare, but provide valuable information about their physical properties. Aims. The total intensity and polarization properties of 16 large SNRs in the Galactic plane are investigated based on observations of the Urumqi λ6 cm polarization survey of the Galactic plane with an angular resolution of 9. 5. Methods. We extracted total intensity and linear polarization maps of large SNRs from the Urumqi λ6 cm survey, obtained their integrated flux densities, and derived the radio spectra by using these flux densities together with previously published flux densities at various frequencies. In particular, Effelsberg λ11 cm and λ21 cm survey data were used to calculate integrated flux densities. The λ6 cm polarization data also delineate the magnetic field structures of the SNRs. Results. We present the first total intensity maps at λ6 cm for SNRs G106.3+2.7, G114.3+0.3, G116.5+1.1, G166.0+4.3 (VRO 42.05.01), G205.5+0.5 (Monoceros Nebula), and G206.9+2.3 (PKS 0646+06) and the first polarization measurements at λ6 cm for SNRs G82.2+5.3 (W63), G106.3+2.7, G114.3+0.3, G116.5+1.1, G166.0+4.3 (VRO 42.05.01), G205.5+0.5 (Monoceros Nebula), and G206.9+2.3 (PKS 0646+06). Most of the newly derived integrated radio spectra are consistent with previous results. The new flux densities obtained from the Urumqi λ6 cm, Effelsberg λ11 cm and λ21 cm surveys are crucial to determine the spectra of SNR G65.1+0.6, G69.0+2.7 (CTB 80), G93.7−0.2, and G114.3+0.3. We find that G192.8−1.1 (PKS 0607+17) consists of background sources, H ii regions, and extended diffuse emission of thermal nature, and conclude that G192.8−1.1 is not a SNR.

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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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Low-frequency radio maps and spectra of supernova remnants

Cited by 29 publications

References 0 publications

Molecular Environments of Three Large Supernova Remnants in the Third Galactic Quadrant: G205.5+0.5, G206.9+2.3, and G213.0–0.6

Molecular Environments of Three Large Supernova Remnants in the Third Galactic Quadrant: G205.5+0.5, G206.9+2.3, and G213.0–0.6

A Sino-Germanλ6 cm polarization survey of the Galactic plane

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

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