scholarly journals Discovery of a new supernova remnant G21.8−3.0

2020 ◽  
Vol 493 (2) ◽  
pp. 2188-2194 ◽  
Author(s):  
X Y Gao ◽  
P Reich ◽  
W Reich ◽  
L G Hou ◽  
J L Han
Keyword(s):  
Spectral Index ◽  
Radio Telescope ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Galactic Plane ◽  
Infrared Emission ◽  
Radio Continuum ◽  
Source Spectrum ◽  
Polarized Emission ◽  
Eastern Half

ABSTRACT Sensitive radio continuum surveys of the Galactic plane are ideal for discovering new supernova remnants (SNRs). From the Sino-German λ6-cm polarization survey of the Galactic plane, an extended shell-like structure has been found at ℓ = 21${^{\circ}_{.}}$8, b = −3${^{\circ}_{.}}$0, which has a size of about 1°. New observations were made with the Effelsberg 100-m radio telescope at λ11 cm to estimate the source spectrum, together with Urumqi λ6-cm and Effelsberg λ21-cm data. The spectral index of G21.8−3.0 was found to be α = −0.72 ± 0.16. Polarized emission was mostly detected in the eastern half of G21.8−3.0 at both λ6 and λ11 cm. These properties, together with the Hα filament along its northern periphery and the lack of infrared emission, indicate that the emission is non-thermal, as is usual in shell-type SNRs.

scholarly journals 20 cm VLA radio-continuum study of M31-images and point source catalogues DR2: Extraction of a supernova remnant sample

2014 ◽  
pp. 15-24 ◽  
Author(s):  
T.J. Galvin ◽  
M.D. Filipovic
Keyword(s):  
Point Source ◽  
Spectral Index ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Small Population ◽  
Radio Continuum ◽  
X Ray ◽  
Search Area ◽  
Frequency Domains ◽  
Discrete Radio Sources

We present Data Release 2 of the Point Source Catalogue created from a series of previously constructed radio-continuum images of M31 at ?=20 cm (v=1.4 GHz) from archived VLA observations. In total, we identify a collection of 916 unique discrete radio sources across the field of M31. Comparing these detected sources to those listed by Gelfand et al. (2004) at ?=92 cm, the spectral index of 98 sources has been derived. The majority (73%) of these sources exhibit a spectral index of ?<-0.6, indicating that their emission is predominantly non-thermal in nature, which is typical for background objects and Supernova Remnants (SNRs). Additionally, we investigate the presence of radio counterparts for some 156 SNRs and SNR candidates, finding a total of only 13 of these objects in our images within a 500 search area. Auxiliary optical, radio and X-ray catalogues were cross referenced highlighting a small population of SNRs and SNR candidates common to multi frequency domains.

scholarly journals Supernova Remnants as Radio Sources

1968 ◽  
Vol 21 (5) ◽  
pp. 739 ◽  
Author(s):  
MJL Kesteven
Keyword(s):  
Spectral Index ◽  
Radio Telescope ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Radio Sources ◽  
Evolutionary Path ◽  
Contour Maps ◽  
Galactic Sources ◽  
Cross Type

The results of a survey with the 1 mile Molonglo cross-type radio telescope of nonthermal galactic sources are discussed in terms of supernova remnant theories. The contour maps obtained indicate that most sources are consistent with a portion of a shell of emission. The results suggest that a remnant's spectral index is independent of its age. A supernova remnant evolutionary path is also derived, and compared with the path predicted by the various theories.

scholarly journals Extended Polarized Emission Structures in the Galactic Plane at 11 cm Wavelength

1990 ◽  
Vol 140 ◽  
pp. 63-64
Author(s):  
N. Junkes ◽  
E. Fürst ◽  
W. Reich
Keyword(s):  
Supernova Remnants ◽  
Spiral Structure ◽  
Galactic Plane ◽  
Radio Sources ◽  
Galactic Magnetic Field ◽  
Background Component ◽  
Polarized Emission ◽  
The Galaxy ◽  
Galactic Longitude ◽  
Thermal Background

Data from the Effelsberg Galactic plane survey at 11 cm wavelength have been used to produce a survey of polarized intensity in the first Galactic quadrant. Besides polarized sources (Supernova remnants and extragalactic objects) extended polarized emission features are visible, which are not connected to distinct radio sources. To decide whether these features reflect characteristics of the local field or the distant spiral structure of the Galaxy we performed an integration of polarized intensities as a function of Galactic longitude. An anticorrelation with the thermal background component suggests a distance of more than 6 kpc for some components of the polarized emission. This enables us to derive an upper limit for the uniform component of the Galactic magnetic field.

scholarly journals 8·8 GHz Radio Observations of 12 Suggested Supernova Remnants

1973 ◽  
Vol 26 (3) ◽  
pp. 379 ◽  
Author(s):  
JR Dickel ◽  
DK Milne ◽  
AR Kerr ◽  
JG Ables
Keyword(s):  
Flux Density ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Galactic Plane ◽  
Small Diameter ◽  
Radio Sources ◽  
Radio Observations ◽  
Frequency Measurements ◽  
Thermal Spectrum

Brightness distributions and flux densities at 8�8 GHz are presented for 12 small-diameter radio sources near the galactic plane. Each of these sources has been classified at one time or another as a supernova remnant. For one source, G295� 2 - 0�6, the flux density at 8�8 GHz confirms the thermal spectrum suggested by lower frequency measurements and indicates that it is not a supernova remnant. Another source, G309� 6+ 1�7, is thought to be extragalactic.

scholarly journals Radio Emission from the Supernova Remnant Vela-X

1968 ◽  
Vol 21 (2) ◽  
pp. 201 ◽  
Author(s):  
DK Milne
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Radio Emission ◽  
Spectral Index ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Magnetic Field Direction ◽  
Radio Observations ◽  
Optical Identification ◽  
Polarization Measurements

Radio observations are presented of the fairly large galactic complex Vela-X, Y, and Z. These sources are believed to be the remnant of a supernova having an optical identification with the filamentary nebula Stromlo 16. The brightness distributions, obtained at four frequencies, indicate an open annular structure reminiscent of other supernova remnants. The variation of spectral index over the region is investigated and shows that the radiation is substantially nontherm81, the integrated fluxes yielding a spectral index of -0,3. A high resolution distribution of magnetic field direction is deduced from polarization measurements made at three frequencies; a circumferential magnetic field is a possible interpretation of the field orientations.

scholarly journals The Radio Morphology and Possible Nature of 3C 58

1983 ◽  
Vol 101 ◽  
pp. 341-342
Author(s):  
Ma Er ◽  
Richard G. Strom
Keyword(s):  
Spectral Index ◽  
Radio Telescope ◽  
Intensity Distribution ◽  
Supernova Remnant ◽  
Published Data ◽  
Rotation Measure

Observations have been made of the supernova remnant 3C 58 with the Westerbork Synthesis Radio Telescope at 6 and 49 cm. These measurements provide us with greater resolution and sensitivity than that attained with previously published data. The 49 cm map has been used for comparison with an existing 21 cm one (Wilson and Weiler, 1976) to obtain information on the spectral index, rotation measure and depolarization. The 6 cm map is valuable both for its greater resolution, and for comparing with an observation made with the same instrument eight years previously. The total intensity distribution is shown in Figure 1.

scholarly journals A Nonthermal Superbubble in the Irregular Galaxy IC 10

1988 ◽  
Vol 101 ◽  
pp. 465-467
Author(s):  
Evan D. Skillman
Keyword(s):  
High Resolution ◽  
Spectral Index ◽  
Supernova Remnant ◽  
Radio Continuum ◽  
Irregular Galaxy ◽  
Large Size ◽  
Ic 10

AbstractNew high resolution radio continuum images of the nearby irregular galaxy IC 10 have revealed a large (> 250 pc) nonthermal source. The source is roughly circular with a spectral index of ∼ –0.5, and is most likely a very large supernova remnant. Its large size suggests that it is the result of several supernovae, and may be related to the supershells observed in our own and other galaxies.

scholarly journals Radio observations of supernova remnant G1.9+0.3

2019 ◽  
Vol 492 (2) ◽  
pp. 2606-2621 ◽  
Author(s):  
Kieran J Luken ◽  
Miroslav D Filipović ◽  
Nigel I Maxted ◽  
Roland Kothes ◽  
Ray P Norris ◽  
...  
Keyword(s):  
Spectral Index ◽  
Supernova Remnant ◽  
Radio Spectrum ◽  
Northern Region ◽  
Radio Continuum ◽  
Expansion Rate ◽  
Continuum Emission ◽  
Rotation Measure ◽  
Cas A ◽  
Recent Epoch

ABSTRACT We present 1–10 GHz radio continuum flux density, spectral index, polarization, and rotation measure (RM) images of the youngest known Galactic supernova remnant (SNR) G1.9+0.3, using observations from the Australia Telescope Compact Array. We have conducted an expansion study spanning eight epochs between 1984 and 2017, yielding results consistent with previous expansion studies of G1.9+0.3. We find a mean radio continuum expansion rate of (0.78 ± 0.09) per cent yr−1 (or ∼8900 km s−1 at an assumed distance of 8.5 kpc), although the expansion rate varies across the SNR perimetre. In the case of the most recent epoch between 2016 and 2017, we observe faster-than-expected expansion of the northern region. We find a global spectral index for G1.9+0.3 of −0.81 ± 0.02 (76 MHz–10 GHz). Towards the northern region, however, the radio spectrum is observed to steepen significantly (∼−1). Towards the two so-called (east and west) ‘ears’ of G1.9+0.3, we find very different RM values of 400–600 and 100–200 rad m2, respectively. The fractional polarization of the radio continuum emission reaches (19 ± 2) per cent, consistent with other, slightly older, SNRs such as Cas A.

scholarly journals Possible Contributions of Supernova Remnants to the Soft X-ray Diffuse Background (0.1 - 1 keV)

1983 ◽  
Vol 101 ◽  
pp. 361-365
Author(s):  
W. T. Sanders ◽  
D. N. Burrows ◽  
D. McCammon ◽  
W. L. Kraushaar
Keyword(s):  
Supernova Remnants ◽  
Large Scale ◽  
Supernova Remnant ◽  
Galactic Halo ◽  
Galactic Plane ◽  
X Rays ◽  
X Ray ◽  
Band Emission ◽  
Diffuse Background ◽  
Almost All

Almost all of the B band (0.10–0.19 keV) and C band (0.15–0.28 keV) X-rays probably originate in a hot region surrounding the Sun, which Cox and Anderson have modeled as a supernova remnant. This same region may account for a significant fraction of the M band (0.5–1 keV) X-rays if the nonequilibrium models of Cox and Anderson are applicable. A population of distant SNR similar to the local region, with center-to-center spacing of about 300 pc, could provide enough galactic M band emission to fill in the dip in the count rate in the galactic plane that would otherwise be present due to absorption of both the extra-galactic power law flux and any large-scale-height stellar (or galactic halo) emission.

scholarly journals Aperture Synthesis Observations of the Supernova Remnant G73.9+0.9

1988 ◽  
Vol 101 ◽  
pp. 297-300
Author(s):  
P. Chastenay ◽  
S. Pineault
Keyword(s):  
Spectral Index ◽  
Supernova Remnant ◽  
Aperture Synthesis ◽  
Radio Continuum ◽  
General Morphology ◽  
Spatially Resolved ◽  
A Value ◽  
Shell Type

AbstractRadio continuum observations, obtained with the DRAO Synthesis Telescope, are presented of the new supernova remnant (SNR) G73.9+0.9. Our map at 1420 MHz shows indications of spatially resolved knots of emission in the brightest part of the remnant. The 408 MHz map, although of lower resolution, shows the same general morphology. The spectral index α (Sv∝v−α) between 1420 and 408 MHz is about 0.5, a value typical for shell type SNRs. The morphology however is more suggestive of a filled centre SNR.

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