scholarly journals Unravelling the origin of extended radio emission in narrow-line Seyfert 1 galaxies with the JVLA

2021 ◽  
Author(s):  
E. Järvelä ◽  
R. Dahale ◽  
L. Crepaldi ◽  
M. Berton ◽  
E. Congiu ◽  
...  
Keyword(s):  
Radio Emission ◽  
Narrow Line ◽  
Extended Radio

scholarly journals Study of the extended radio emission of two supernova remnants and four planetary nebulae associated with MIPSGAL bubbles

2014 ◽  
Vol 445 (4) ◽  
pp. 4504-4514 ◽  
Author(s):  
A. Ingallinera ◽  
C. Trigilio ◽  
G. Umana ◽  
P. Leto ◽  
C. Agliozzo ◽  
...  
Keyword(s):  
Radio Emission ◽  
Supernova Remnants ◽  
Planetary Nebulae ◽  
Extended Radio

scholarly journals Radio morphology of southern narrow-line Seyfert 1 galaxies with Very Large Array observations*

2020 ◽  
Vol 498 (1) ◽  
pp. 1278-1297
Author(s):  
S Chen ◽  
E Järvelä ◽  
L Crepaldi ◽  
M Zhou ◽  
S Ciroi ◽  
...  
Keyword(s):  
Star Formation ◽  
Radio Emission ◽  
Large Mass ◽  
Large Array ◽  
Narrow Line ◽  
Diffuse Emission ◽  
Jets And Outflows ◽  
Very Large Array ◽  
Radio Jets ◽  
New Radio

ABSTRACT We present the results of new radio observations carried out with the Karl G. Jansky Very Large Array C-configuration at 5.5 GHz for a sample of southern narrow-line Seyfert 1 galaxies (NLS1s). This work increases the number of known radio-detected NLS1s in the Southern hemisphere, and confirms that the radio emission of NLS1s is mainly concentrated in a central region at kpc-scale and only a few sources show diffuse emission. In radio-quiet NLS1s, the radio luminosity tends to be higher in steep-spectrum sources and be lower in flat-spectrum sources, which is opposite to radio-loud NLS1s. This may be because the radio emission of steep NLS1s is dominated by misaligned jets, active galactic nucleus driven outflows, or star formation superposing on a compact core. Instead the radio emission of flat NLS1s may be produced by a central core that has not yet developed radio jets and outflows. We discover new NLS1s harbouring kpc-scale radio jets and confirm that a powerful jet does not require a large-mass black hole to be generated. We also find sources dominated by star formation. These NLS1s could be new candidates in investigating the radio emission of different mechanisms.

scholarly journals EXTENDED RADIO EMISSION IN MOJAVE BLAZARS: CHALLENGES TO UNIFICATION

2010 ◽  
Vol 710 (1) ◽  
pp. 764-782 ◽  
Author(s):  
P. Kharb ◽  
M. L. Lister ◽  
N. J. Cooper
Keyword(s):  
Radio Emission ◽  
Extended Radio

Extended radio emission around Cygnus X-3: a possible jet-driven bubble as in Cygnus X-1?

2008 ◽  
Author(s):  
J. Martí ◽  
J. R. Sanchez-Sutil ◽  
P. Luque-Escamilla ◽  
J. A. Combi ◽  
A. J. Muñoz-Arjonilla ◽  
...  
Keyword(s):  
Radio Emission ◽  
Extended Radio

scholarly journals Mystery solved: discovery of extended radio emission in the merging galaxy cluster Abell 2146

2017 ◽  
Vol 475 (2) ◽  
pp. 2743-2753 ◽  
Author(s):  
J Hlavacek-Larrondo ◽  
M-L Gendron-Marsolais ◽  
D Fecteau-Beaucage ◽  
R J van Weeren ◽  
H R Russell ◽  
...  
Keyword(s):  
Radio Emission ◽  
Galaxy Cluster ◽  
Extended Radio

scholarly journals Radio observations of the merging galaxy cluster Abell 520

2019 ◽  
Vol 622 ◽  
pp. A20 ◽  
Author(s):  
D. N. Hoang ◽  
T. W. Shimwell ◽  
R. J. van Weeren ◽  
G. Brunetti ◽  
H. J. A. Röttgering ◽  
...  
Keyword(s):  
Mach Number ◽  
Radio Emission ◽  
Low Frequency ◽  
Galaxy Cluster ◽  
Shock Acceleration ◽  
Relativistic Electrons ◽  
Diffusive Shock Acceleration ◽  
Cluster Emission ◽  
X Ray ◽  
Extended Radio

Context. Extended synchrotron radio sources are often observed in merging galaxy clusters. Studies of the extended emission help us to understand the mechanisms in which the radio emitting particles gain their relativistic energies. Aims. We examine the possible acceleration mechanisms of the relativistic particles that are responsible for the extended radio emission in the merging galaxy cluster Abell 520. Methods. We performed new 145 MHz observations with the LOw Frequency ARay (LOFAR) and combined these with archival Giant Metrewave Radio Telescope (GMRT) 323 MHz and Very Large Array (VLA) 1.5 GHz data to study the morphological and spectral properties of extended cluster emission. The observational properties are discussed in the framework of particle acceleration models associated with cluster merger turbulence and shocks. Results. In Abell 520, we confirm the presence of extended (760 × 950 kpc2) synchrotron radio emission that has been classified as a radio halo. The comparison between the radio and X-ray brightness suggests that the halo might originate in a cocoon rather than from the central X-ray bright regions of the cluster. The halo spectrum is roughly uniform on the scale of 66 kpc. There is a hint of spectral steepening from the SW edge towards the cluster centre. Assuming diffusive shock acceleration (DSA), the radio data are suggestive of a shock Mach number of ℳSW = 2.6−0.2+0.3 that is consistent with the X-ray derived estimates. This is in agreement with the scenario in which relativistic electrons in the SW radio edge gain their energies at the shock front via acceleration of either thermal or fossil electrons. We do not detect extended radio emission ahead of the SW shock that is predicted if the emission is the result of adiabatic compression. An X-ray surface brightness discontinuity is detected towards the NE region that may be a counter shock of Mach number ℳNEX = 1.52±0.05. This is lower than the value predicted from the radio emission which, assuming DSA, is consistent with ℳNE = 2.1 ± 0.2. Conclusions. Our observations indicate that the radio emission in the SW of Abell 520 is likely effected by the prominent X-ray detected shock in which radio emitting particles are (re-)accelerated through the Fermi-I mechanism. The NE X-ray discontinuity that is approximately collocated with an edge in the radio emission hints at the presence of a counter shock.

scholarly journals Clusters with extended radio emission at high frequencies

1978 ◽  
Vol 79 ◽  
pp. 157-159
Author(s):  
R. Wielebinski
Keyword(s):  
Radio Emission ◽  
Direct Measurement ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Coma Cluster ◽  
Extended Source ◽  
High Frequencies ◽  
Extended Radio ◽  
Extended Component ◽  
Perseus Cluster

The existence of ‘haloes’ in clusters of galaxies was deduced by Ryle and Windram (1968) for the Perseus cluster and by Willson (1970) for the Coma cluster at 408 MHz by comparing total flux measured by a single dish with the sum of fluxes of radio sources found in the field. A direct measurement of the extended source Coma C was made by Jaffe et al. (1976) at 610 MHz. the failure to detect the halo of Coma at higher frequencies is attributed by all authors to a steep spectrum of this extended component.

scholarly journals The Intergalactic Medium

1982 ◽  
Vol 97 ◽  
pp. 453-459
Author(s):  
A. C. Fabian ◽  
A. K. Kembhavi
Keyword(s):  
Radio Emission ◽  
Intergalactic Medium ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Intergalactic Gas ◽  
X Ray ◽  
Extended Radio ◽  
X Ray Background ◽  
Ngc 1275 ◽  
Intracluster Gas

The density of intergalactic gas may be an important parameter in the formation of extended radio sources. It may range from ∼ 0.1 particle cm−3 in the centres of some rich clusters of galaxies down to 10−8cm−3 or less in intercluster space. The possible influence of the intracluster gas surrounding NGC 1275 on its radio emission is discussed, and the possibility that a significant fraction of the X-ray background is due to a hot intergalactic medium is explored in some detail.

scholarly journals Revealing the extended radio emission from the gamma-ray binary HESS J0632+057

2011 ◽  
Vol 533 ◽  
pp. L7 ◽  
Author(s):  
J. Moldón ◽  
M. Ribó ◽  
J. M. Paredes
Keyword(s):  
Radio Emission ◽  
Gamma Ray ◽  
Extended Radio
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