Simulated synchrotron emission for the Tycho’s supernova remnants: an asymmetric initial mass model

2020 ◽  
Vol 494 (2) ◽  
pp. 1531-1538
Author(s):  
A Moranchel-Basurto ◽  
P F Velázquez ◽  
G Ares de Parga ◽  
E M Reynoso ◽  
E M Schneiter ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Brightness Distribution ◽  
Radio Continuum ◽  
Initial Mass ◽  
Continuum Emission ◽  
Synchrotron Emission ◽  
Mass Model ◽  
Mhd Simulations ◽  
Tycho’S Snr ◽  
Good Agreement

ABSTRACT We have performed 3D magnetohydrodynamics (MHD) numerical simulations with the aim of exploring the scenario in which the initial mass distribution of a supernova (SN) explosion is anisotropic. The purpose is to analyse if this scenario can also explain the radio-continuum emission and the expansion observed in young supernova remnants (SNRs). To study the expansion, synthetic polarized synchrotron emission maps were computed from the MHD simulations. We found a good agreement (under a number of assumptions) between this expansion study and previous observational results applied to Tycho’s SNR, which represents a good example of asymmetric young SNRs. Additionally, both the observed morphology and the brightness distribution are qualitatively reproduced.

The diagnostic power of radio spectra from star-forming galaxies

2019 ◽  
Vol 15 (S341) ◽  
pp. 177-186
Author(s):  
Eric J. Murphy
Keyword(s):  
Star Formation ◽  
Dust Emission ◽  
Cosmic Ray ◽  
Microwave Emission ◽  
Radio Continuum ◽  
Continuum Emission ◽  
H Ii Regions ◽  
Synchrotron Emission ◽  
Very Large Array ◽  
Star Forming

AbstractRadio continuum emission from galaxies is powered by a combination of distinct physical processes, each providing unique diagnostic information. Over frequencies spanning ∼ 1–120 GHz, radio spectra of star-forming galaxies are primarily comprised of: (1) non-thermal synchrotron emission powered by accelerated cosmic-ray electrons/positrons; (2) free-free emission from young massive star-forming (H ii) regions; (3) anomalous microwave emission, which is a dominant, but completely unconstrained, foreground in cosmic microwave background experiments; and (4) cold, thermal dust emission that accounts for most of the dust and total mass content in the interstellar medium in galaxies. In this proceeding, we discuss these key energetic processes that contribute to the radio emission from star-forming galaxies, with an emphasis on frequencies ≳30 GHz, where current investigations of star formation within nearby galaxies show that the free-free emission begins to dominate over non-thermal synchrotron emission. We also discuss how planned radio facilities that will access these frequencies, such as a next-generation Very Large Array (ngVLA), will be transformative to our understanding of the star formation process in galaxies.

Millimetre Continuum Observations of AGNs and IRAS Galaxies

1996 ◽  
Vol 13 (2) ◽  
pp. 182-182
Author(s):  
Ray Norris
Keyword(s):  
Active Galactic Nucleus ◽  
Black Body ◽  
Active Galaxies ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Starburst Galaxy ◽  
H Ii Regions ◽  
Synchrotron Emission ◽  
Compact Array ◽  
Three Components

The 3 mm radio continuum emission from active galaxies consists of three components: (1)Synchrotron emission from the active galactic nucleus (AGN), which is over 1 Jy in 3C273 but which is not significant in most of the types of galaxy considered here.(2)Free–free emission from H II regions. The flux of this in a starburst galaxy is typically of the order of 10 mJy and could be imaged with a 3 mm-capable Australia Telescope Compact Array (ATCA).(3)Emission from the tail of the 50–100 K black-body spectrum of the dust. For example, the dust in Arp 220 (redshift of 0·02) at a temperature of 50 K has a flux of 30 mJy at 3 mm. Interestingly, this flux does not decrease substantially with redshift, as the decrease in brightness is compensated for by the redshifting of the steep edge of the blackbody curve, and so infrared-bright galaxies can be studied up to high redshifts with existing instruments.

scholarly journals The resolved radio–FIR correlation in nearby galaxies with Herschel and Spitzer

2011 ◽  
Vol 7 (S284) ◽  
pp. 400-403
Author(s):  
Fatemeh S. Tabatabaei ◽  
Eva Schinnerer ◽  
Eric Murphy ◽  
Rainer Beck ◽  
Annie Hughes ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Diffusion Length ◽  
Spatial Scales ◽  
Cosmic Ray ◽  
Far Infrared ◽  
Scale Dependence ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Synchrotron Emission ◽  
Nearby Galaxies

AbstractWe investigate the correlation between the far-infrared (FIR) and radio continuum emission from NGC6946 on spatial scales between 0.9 and 17 kpc. We use the Herschel PACS (70, 100, 160μm) and SPIRE (250μm) data from the KINGFISH project. Separating the free-free and synchrotron components of the radio continuum emission, we find that FIR is better correlated with the free-free than the synchrotron emission. Compared to a similar study in M33 and M31, we find that the scale dependence of the synchrotron–FIR correlation in NGC6946 is more similar to M31 than M33. The scale dependence of the synchrotron–FIR correlation can be explained by the turbulent-to-ordered magnetic field ratio or, equivalently, the diffusion length of the cosmic ray electrons in these galaxies.

scholarly journals Dark Supernova Remnants Revealed by CO-Line Bubbles in the W43 Molecular Complex along the 4-kpc Galactic Arm

Galaxies ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 13
Author(s):  
Yoshiaki Sofue
Keyword(s):  
Molecular Clouds ◽  
Supernova Remnants ◽  
Dust Emission ◽  
Radio Continuum ◽  
Young Stellar Objects ◽  
Continuum Emission ◽  
Giant Molecular Clouds ◽  
Turbulent Structures ◽  
Stellar Objects ◽  
Receiver System

Fine structure of the density distribution in giant molecular clouds (GMCs) around W43 (G31+00+90 km s−1at ∼5.5 kpc) was analyzed using the FUGIN* CO-line survey at high-angular (20”∼0.5 pc) and velocity (1.3 km s−1) resolutions (*Four-receiver-system Unbiased Galactic Imaging survey with the Nobeyama 45-m telescope). The GMCs show highly turbulent structures, and the eddies are found to exhibit spherical bubble morphology appearing in narrow ranges of velocity channels. The bubbles are dark in radio continuum emission, unlike usual supernova remnants (SNR) or HII regions, and in infrared dust emission, unlike molecular bubbles around young stellar objects. The CO bubbles are interpreted as due to fully evolved buried SNRs in molecular clouds after rapid exhaustion of the released energy in dense molecular clouds. Then, the CO bubbles may be a direct evidence for exciting and maintaining the turbulence in GMCs by SN origin. Search for CO bubbles as “dark SNRs” (dSNR) will have implication to estimate the supernova rate more accurately, and hence the star formation activity in the Milky Way.

scholarly journals Radio continuum emission in the northern Galactic plane: Sources and spectral indices from the THOR survey

2018 ◽  
Vol 619 ◽  
pp. A124 ◽  
Author(s):  
Y. Wang ◽  
S. Bihr ◽  
M. Rugel ◽  
H. Beuther ◽  
K. G. Johnston ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Milky Way ◽  
Galactic Plane ◽  
High Redshift ◽  
High Sensitivity ◽  
Large Percentage ◽  
Radio Continuum ◽  
Continuum Emission ◽  
High Angular Resolution ◽  
Spectral Indices

Context Radio continuum surveys of the Galactic plane can find and characterize H II regions, supernova remnants (SNRs), planetary nebulae (PNe), and extragalactic sources. A number of surveys at high angular resolution (≤25″) at different wavelengths exist to study the interstellar medium (ISM), but no comparable high-resolution and high-sensitivity survey exists at long radio wavelengths around 21 cm. Aims. Our goal is to investigate the 21 cm radio continuum emission in the northern Galactic plane at < 25″ resolution. Methods We observed a large percentage of the Galactic plane in the first quadrant of the Milky Way (l = 14.0−67.4° and |b| ≤ 1.25°) with the Karl G. Jansky Very Large Array (VLA) in the C-configuration covering six continuum spectral windows (SPW). These data provide a detailed view on the compact as well as extended radio emission of our Galaxy and thousands of extragalactic background sources. Results We used the BLOBCAT software and extracted 10 916 sources. After removing spurious source detections caused by the side lobes of the synthesized beam, we classified 10 387 sources as reliable detections. We smoothed the images to a common resolution of 25″ and extracted the peak flux density of each source in each SPW to determine the spectral indices α (assuming I(ν) ∝ να). By cross-matching with catalogs of H II regions, SNRs, PNe, and pulsars, we found radio counterparts for 840 H II regions, 52 SNRs, 164 PNe, and 38 pulsars. We found 79 continuum sources that are associated with X-ray sources. We identified 699 ultra-steep spectral sources (α < −1.3) that could be high-redshift galaxies. About 9000 of the sources we extracted are not classified specifically, but based on their spatial and spectral distribution, a large percentage of these are likely to be extragalactic background sources. More than 7750 sources do not have counterparts in the SIMBAD database and more than 3760 sources do not have counterparts in the NED database. Conclusions Studying the long wavelengths centimeter continuum emission and the associated spectral indices allows us to characaterize a large percentage of Galactic and extragalactic radio sources in the area of the northern inner Milky Way. This database will be extremely useful for future studies of a diverse set of astrophysical objects.

scholarly journals SRAO CO Observation of Supernova Remnants in l = 70° to 190°

2013 ◽  
Vol 9 (S296) ◽  
pp. 183-187
Author(s):  
Il-Gyo Jeong ◽  
Bon-Chul Koo
Keyword(s):  
Hydrodynamic Model ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Supernova Remnants ◽  
Spatial Relation ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Astronomy Observatory ◽  
Western Half ◽  
Co Emission

AbstractWe present the results 12CO J = 1–0 line observations of eleven Galactic supernova remnants (SNRs) between l = 70° and 190° obtained using the Seoul Radio Astronomy Observatory (SRAO) 6-m radio telescope. We detected CO emission towards most of the remnants. In seven SNRs, molecular clouds show a good spatial relation with their radio morphology: G73.9+0.9, G84.2−0.8, G85.4+0.7, G85.9−0.6, G93.3+6.9 (DA530), 94.0+1.0 (3C 434.1), and G182.4+4.3. Two SNRs are particularly interesting. In G85.4+0.7, there is a filamentary molecular cloud aligned along the south-east boundary of the remnant. This cloud extends to the nearby Hii region G84.9+0.5. If the molecular cloud is associated with both the Hii region and the SNR, the distance to the SNR would be 5–7 kpc. In 3C 434.1, there is a large molecular cloud blocking the western half of the remnant where the radio continuum emission is faint. The cloud shows a very good spatial correlation with radio continuum features, which strongly suggests the physical association of the cloud with the SNR. This gives a distance of 3 kpc to the SNR. We performed 12CO J = 2–1 line observations of this cloud using Kölner Observatorium für Sub-Millimeter Astronomie (KOSMA) 3-m telescope and found a region where the 12CO J = 2–1/1–0 line ratio is high. We present a hydrodynamic model showing that 3C434.1 could have resulted from a SN explosion occurred just outside the boundary of a thin, molecular cloud.

scholarly journals Dark supernova remnant

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Yoshiaki Sofue
Keyword(s):  
Supernova Remnants ◽  
Supernova Remnant ◽  
Rapid Evolution ◽  
Line Emission ◽  
Radio Continuum ◽  
Star Formation History ◽  
Continuum Emission ◽  
Round Hole ◽  
Formation History ◽  
The Galaxy

Abstract An almost perfect round hole of CO-line emission with a diameter of 3.7 pc was found in a molecular cloud (MC) centered on G35.75−0.25 (l = 35${{^{\circ}_{.}}}$75, b = −0${{^{\circ}_{.}}}$25) at radial velocity of 28 km s−1. The hole is quiet in radio continuum emission, unlike the usual supernova remnants (SNR), and the molecular edge is only weakly visible in 8 and 24 μm dust emissions. The hole may be either a fully evolved molecular bubble around a young stellar object (YSO), or a relic of a radio-quiet SNR that has already stopped expansion after rapid evolution in the dense MC as a buried SNR. Because G35.75 exhibits quite different properties from YSO-driven bubbles of the same size, we prefer the latter interpretation. The existence of such a “dark” SNR would affect the estimation of the supernova rate, and therefore the star formation history, in the Galaxy.

Galactic nonthermal radiation. Distribution of SNRs and pulsars

1979 ◽  
Vol 84 ◽  
pp. 113-118
Author(s):  
R. Wielebinski
Keyword(s):  
Supernova Remnants ◽  
Angular Resolution ◽  
Galactic Plane ◽  
Hii Regions ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Nonthermal Radiation ◽  
Radiation Distribution ◽  
Nonthermal Emission ◽  
The Galaxy

All sky surveys of the radio continuum emission give us the basic information on the distribution of the nonthermal emission in the Galaxy. At metre wavelengths, where nonthermal emission is dominant, good angular resolution is difficult to attain. For many years the best surveys near 2 m wavelength gave us a picture of the galaxy with ∼ 2° resolution. At centimetre wavelengths, where arc min resolution is available, the intense HII regions dominate the radio sky. Supernova remnants have a distribution somewhat similar to that of the discrete HII regions and must be delineated by various methods in high resolution galactic plane surveys in the decimetre wavelength range.

scholarly journals A multi-frequency study of the Wolf-Rayet blue compact dwarf galaxy He2-10

1999 ◽  
Vol 193 ◽  
pp. 610-611
Author(s):  
David I. Méndez ◽  
César Esteban ◽  
Miroslav D. Filipović ◽  
Matthias Ehle ◽  
Prank Haberl ◽  
...  
Keyword(s):  
High Resolution ◽  
Supernova Remnants ◽  
Dwarf Galaxy ◽  
Mechanical Action ◽  
Radio Continuum ◽  
High Resolution Spectroscopy ◽  
Continuum Emission ◽  
Star Forming ◽  
The Galaxy ◽  
Blue Compact Dwarf Galaxy

We present preliminary results on multi-wavelength observations of the Wolf-Rayet Blue Compact Dwarf Galaxy He2–10. These observations include Hα and continuum imaging, high-resolution Hα spectroscopy, high-resolution radio-continuum mapping at 6.3 and 3.5 cm and X-ray mapping. The deep Hα image reveals that the galaxy consists of a complex system of different star-forming knots surrounded by kpc-scale bubble-like and filamentary structures. The most interesting structure is a bipolar superbubble centered on the most intense star-formation knot. High-resolution spectroscopy of this structure indicates that it is expanding with a velocity in the range 75–250 km s−1. This kind of outflows is likely to be produced by the mechanical action of stellar winds and supernovae explosions in the intense starbursts that the galaxy hosts. This scenario is consistent with the finding of a very steep radio spectral index in the extended radio continuum emission (α = −0.59) that confirms the presence of a large number of supernova remnants in the galaxy.

scholarly journals Bright Prospects: Comparing the Hα Survey with Large-scale Radio Continuum Emission

1998 ◽  
Vol 15 (1) ◽  
pp. 50-55
Author(s):  
A. R. Duncan ◽  
R. F. Haynes
Keyword(s):  
Supernova Remnants ◽  
Large Scale ◽  
Galactic Plane ◽  
Thermal Emission ◽  
High Sensitivity ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Low Density ◽  
Polar Plumes ◽  
Spiral Arm

AbstractProspects for comparisons between the AAO/UKST Hα survey and large-scale radio continuum emission are considered, with particular reference to the recently completed Parkes 2·4 GHz survey of the southern Galactic Plane. Both these surveys have a high sensitivity to thermal emission, and comparisons between the Parkes work and previous Hα surveys show many objects in common. Possibilities for new detections include: a number of new supernova remnants; the faint extensions and envelopes surrounding ‘classical’ HII complexes, and other faint regions of thermal emission; several active HII complexes, including an outflow of ionised gas from IC 4628 and a number of bi-polar ‘plumes’ of low-density, thermal material apparently associated with HII complexes on the Carina spiral arm.

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