scholarly journals The analysis of the possible thermal emission at radio frequencies from an evolved supernova remnant HB 3 (G132.7+1.3): Revisited

2008 ◽  
pp. 67-71 ◽  
Author(s):  
D. Onic ◽  
D. Urosevic
Keyword(s):  
Flux Density ◽  
Molecular Cloud ◽  
Supernova Remnant ◽  
Thermal Emission ◽  
Radio Spectrum ◽  
Thermal Component ◽  
Support Interaction ◽  
Density Values ◽  
H Ii Region ◽  
Radio Frequencies

It has recently been reported that some of the flux density values for an evolved supernova remnant (SNR) HB 3 (G132.7+1.3) are not accurate enough. In this work we therefore revised the analysis of the possible thermal emission at radio frequencies from this SNR using the recently published, corrected flux density values. A model including the sum of non-thermal (purely synchrotron) and thermal (bremsstrahlung) components is applied to fit the integrated radio spectrum of this SNR. The contribution of thermal component to the total volume emissivity at 1 GHz is estimated to be ? 37%. The ambient density is also estimated to be n ? 9 cm-3 for T = 104 K. Again we obtained a relatively significant presence of thermal emission at radio frequencies from the SNR, which can support interaction between SNR HB 3 and adjacent molecular cloud associated with the H ii region W3. Our model estimates for thermal component contribution to total volume emissivity at 1 GHz and ambient density are similar to those obtained earlier (? 40 %, ? 10 cm-3 ). It is thus obvious that the corrected flux density values do not affect the basic conclusions.

scholarly journals SN 1987A at Radio Wavelengths

2005 ◽  
Vol 192 ◽  
pp. 89-95
Author(s):  
L. Staveley-Smith ◽  
R.N. Manchester ◽  
B.M. Gaensler ◽  
M.J. Kesteven ◽  
A.K. Tzioumis ◽  
...  
Keyword(s):  
Flux Density ◽  
Spectral Index ◽  
Supernova Remnant ◽  
Expansion Rate ◽  
Radio Luminosity ◽  
Sn 1987A ◽  
Radio Imaging ◽  
Radio Frequencies ◽  
Compact Array

SummarySN1987A has an intrinsic radio luminosity some four orders of magnitude less than SN1993J at maximum, largely a reflection of the tenuous wind . from the progenitor of SN1987A before explosion. Both remnants have an edge-brightened, ring-like morphology though, in the case of SN1987A, the expansion rate is currently only around 3500 km s−1. The flux density of the remnant of SN1987A continues to rise at all measured radio frequencies. Its spectral index is gradually flattening, indicating its transition into the supernova remnant phase. A campaign to increase the resolution of radio imaging by observing at higher frequencies is underway with the Australia Telescope Compact Array (ATCA).

scholarly journals A low-frequency view of mixed-morphology supernova remnant VRO 42.05.01, and its neighbourhood

2019 ◽  
Vol 622 ◽  
pp. A6 ◽  
Author(s):  
M. Arias ◽  
J. Vink ◽  
M. Iacobelli ◽  
V. Domček ◽  
M. Haverkorn ◽  
...  
Keyword(s):  
Spectral Index ◽  
Supernova Remnants ◽  
Galactic Plane ◽  
Low Frequency ◽  
Radio Spectrum ◽  
Optical Data ◽  
Shock Acceleration ◽  
H Ii Region ◽  
Radio Frequencies ◽  
Index Value

Context. Mixed-morphology supernova remnants (MM SNRs) are a mysterious class of objects that display thermal X-ray emission within their radio shell. They are an older class of SNRs, and as such are profoundly affected by the environment into which they evolve. VRO 42.05.01 is a MM SNR of puzzling morphology in the direction of the Galactic anticentre. Aims. Low-frequency radio observations of supernova remnants are sensitive to synchrotron electrons accelerated in the shock front. We aim to compare the low-frequency emission to higher frequency observations to understand the environmental and shock acceleration conditions that have given rise to the observed properties of this source. Methods. We present a LOFAR High Band Antenna map centred at 143 MHz of the region of the Galactic plane centred at l = 166 ° ,  b = 3.5° at 143 MHz, with a resolution of 148″ and an rms noise of 4.4 mJy bm−1. Our map is sensitive to scales as large as 6°. We compared the LOw Frequency ARay (LOFAR) observations to archival higher frequency radio, infrared, and optical data to study the emission properties of the source in different spectral regimes. We did this both for the SNR and for OA 184, an H II region within our field of view. Results. We find that the radio spectral index of VRO 42.05.01 increases at low radio frequencies; i.e. the LOFAR flux is higher than expected from the measured spectral index value at higher radio frequencies. This observed curvature in the low-frequency end of the radio spectrum occurs primarily in the brightest regions of the source, while the fainter regions present a roughly constant power-law behaviour between 143 MHz and 2695 MHz. We favour an explanation for this steepening whereby radiative shocks have high compression ratios and electrons of different energies probe different length scales across the shocks, therefore sampling regions of different compression ratios.

scholarly journals 13CO(J = 1-0) Observations of the Orion Molecular Cloud

1987 ◽  
Vol 115 ◽  
pp. 149-150
Author(s):  
K. Sugitani ◽  
Y. Fukui
Keyword(s):  
Millimeter Wave ◽  
High Velocity ◽  
Molecular Cloud ◽  
High Velocity Resolution ◽  
H Ii Region ◽  
Co Emission

We present new 13CO(J = 1-0) measurements of the Orion molecular cloud. The data were taken with the 4-m millimeter-wave telescope of Nagoya University with a beamwidth of 2.7′. The high velocity resolution of 0.1 km s−1 employed has revealed significant details of the 13CO emission toward the H II region.

scholarly journals Low frequency (74 MHz) radio continuum observations of the inner 13° × 7° of the Galactic center

2013 ◽  
Vol 9 (S303) ◽  
pp. 464-466
Author(s):  
M. Rickert ◽  
F. Yusef-Zadeh ◽  
C. Brogan
Keyword(s):  
High Resolution ◽  
Molecular Cloud ◽  
Supernova Remnant ◽  
Galactic Center ◽  
Low Frequency ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array ◽  
Image Displays ◽  
Western Side

AbstractWe analyze a high resolution (114″ × 60″) 74 MHz image of the Galactic center taken with the Very Large Array (VLA). We have identified several absorption and emission features in this region, and we discuss preliminary results of two Galactic center sources: the Sgr D complex (G1.1–0.1) and the Galactic center lobe (GCL).The 74 MHz image displays the thermal and nonthermal components of Sgr D and we argue the Sgr D supernova remnant (SNR) is consistent with an interaction with a nearby molecular cloud and the location of the Sgr D Hii region on the near side of the Galactic center. The image also suggests that the emission from the eastern side of the GCL contains a mixture of both thermal and nonthermal sources, whereas the western side is primarily thermal.

scholarly journals 17. Optical investigations of radio sources: Introductory Lecture

1957 ◽  
Vol 4 ◽  
pp. 107-122 ◽  
Author(s):  
R. Minkowski
Keyword(s):  
Thermal Emission ◽  
Optical Emission ◽  
Radio Spectrum ◽  
Visual Object ◽  
Supporting Evidence ◽  
Precise Position ◽  
Rosette Nebula ◽  
Important Argument ◽  
Astronomical Object ◽  
Order Of Magnitude

Loose agreement of a radio position of low accuracy with that of some object listed in the NGC is not sufficient to provide the identification of a radio source. Even satisfactory coincidence of a precise position with that of an astronomical object requires supporting evidence. Agreement of the size of the source with that of the visible object, at least in order of magnitude, is an important argument in favour of an identification; exact agreement of sizes can be expected only where radio and optical emission are physically connected. The radio spectrum, the optical spectrum, and the physical characteristics of the visual object also have to be taken into account. Observations of the radio spectrum should be particularly useful to support the identification of sources with H 11 regions which can be recognized from their thermal emission even if they are obscured and optically inaccessible. If all data are available, satisfactory agreement exists between optical and radio observations. The best example of this kind at the moment is perhaps NGC 2237, the Rosette nebula, reported as a source by Ko and Krauss (1955) [1] and also observed by Mills, Little and Sheridan (1956 [11]; see also paper 18).

scholarly journals The H II region-molecular cloud complex W3 - Observations of CO, CS, and HCN

1980 ◽  
Vol 237 ◽  
pp. 711 ◽  
Author(s):  
H. R. Dickel ◽  
J. R. Dickel ◽  
W. J. Wilson ◽  
M. W. Werner
Keyword(s):  
Molecular Cloud ◽  
H Ii Region ◽  
Cloud Complex

scholarly journals On the integrated continuum radio spectrum of supernova remnant W44 (G34.7-0.4): New insights from Planck

2015 ◽  
pp. 29-37 ◽  
Author(s):  
D. Onic
Keyword(s):  
Supernova Remnant ◽  
Dust Emission ◽  
Radio Spectrum ◽  
Radio Continuum ◽  
Continuum Spectrum ◽  
Data Points ◽  
Emission Models ◽  
Continuum Radio ◽  
Emission Detection

In this paper, the integrated continuum radio spectrum of supernova remnant (SNR) W44 was analyzed up to 70 GHz, testing the different emission models that can be responsible for its particular shape. The observations by the Planck space telescope made it possible to analyze the high frequency part of radio emission from SNRs. Although the quality of radio continuum spectrum (a high scatter of data points at same frequencies) prevents us to make definite conclusions, the possibility of spinning dust emission detection towards this remnant is emphasized. In addition, a concave-down feature, due to synchrotron losses, can not be definitely dismissed by the present knowledge of the integrated radio continuum spectrum of this SNR.

scholarly journals Fermi-LAT and WMAP observations of the supernova remnant Puppis A

2013 ◽  
Vol 9 (S296) ◽  
pp. 295-299
Author(s):  
Marie-Hélène Grondin ◽  
John W. Hewitt ◽  
Marianne Lemoine-Goumard ◽  
Thierry Reposeur ◽  
Keyword(s):  
Supernova Remnants ◽  
Supernova Remnant ◽  
Gamma Ray ◽  
High Energy ◽  
Radio Spectrum ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Large Area ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Γ Ray

AbstractThe supernova remnant (SNR) Puppis A (aka G260.4-3.4) is a middle-aged supernova remnant, which displays increasing X-ray surface brightness from West to East corresponding to an increasing density of the ambient interstellar medium at the Eastern and Northern shell. The dense IR photon field and the high ambient density around the remnant make it an ideal case to study in γ-rays. Gamma-ray studies based on three years of observations with the Large Area Telescope (LAT) aboard Fermi have revealed the high energy gamma-ray emission from SNR Puppis A. The γ-ray emission from the remnant is spatially extended, and nicely matches the radio and X-ray morphologies. Its γ-ray spectrum is well described by a simple power law with an index of ~2.1, and it is among the faintest supernova remnants yet detected at GeV energies. To constrain the relativistic electron population, seven years of Wilkinson Microwave Anisotropy Probe (WMAP) data were also analyzed, and enabled to extend the radio spectrum up to 93 GHz. The results obtained in the radio and γ-ray domains are described in detail, as well as the possible origins of the high energy γ-ray emission (Bremsstrahlung, Inverse Compton scattering by electrons or decay of neutral pions produced by proton interactions).

scholarly journals Multi-frequency pulsar studies at high radio frequencies

1996 ◽  
Vol 160 ◽  
pp. 279-282
Author(s):  
Michael Kramer ◽  
Kiriaki M. Xilouris
Keyword(s):  
Magnetic Field ◽  
Flux Density ◽  
Stellar Surface ◽  
Active Part ◽  
Frequency Range ◽  
Density Spectrum ◽  
Density Measurements ◽  
Radio Frequencies ◽  
Dipolar Structure ◽  
The Magnetic Field

AbstractWe report flux density measurements, polarimetric and timing observations of pulsars made at the highest radio frequencies to date, covering the widest frequency range from 1.4 GHz to 86 GHz. We find that the magnetic field maintains its dipolar structure throughout the active part of the magnetosphere, a region located close to the stellar surface and confined to a small slab of a few stellar radii. The change in width and shape of pulse profiles saturates at mm-wavelengths while the depolarization accelerates, leading to almost completely depolarized emission. Two pulsars seem to exhibit a turn-up in their flux density spectrum at mm-wavelengths.

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