The structure of the radio halo

2008 ◽  
pp. 72-76
Author(s):  
Frazer Owen
Keyword(s):  
Radio Halo

Stellar feedback in dwarf irregular galaxies with radio continuum observations

2018 ◽  
Vol 14 (S344) ◽  
pp. 255-258
Author(s):  
Volker Heesen ◽  
Aritra Basu ◽  
Elias Brinks ◽  
George Heald ◽  
Andrew Fletcher ◽  
...  
Keyword(s):  
Star Formation ◽  
Low Frequency ◽  
Cosmic Ray ◽  
Radio Continuum ◽  
Very Large Array ◽  
Radio Halo ◽  
Spatially Resolved ◽  
Ic 10 ◽  
Irregular Galaxies ◽  
Dwarf Irregular Galaxies

AbstractLow-mass dwarf irregular galaxies are subject to outflows, in which cosmic rays may play a very important role; they can be traced via their electron component, the cosmic ray electrons (CRe), in the radio continuum as non-thermal synchrotron emission. With the advent of sensitive low-frequency observations, such as with the Low-Frequency Array (LOFAR), we can trace CRe far away from star formation sites. Together with GHz-observations, such as with the Very Large Array (VLA), we can study spatially resolved radio continuum spectra at matched angular resolution and sensitivity. Here, we present results from our 6-GHz VLA survey of 40 nearby dwarf galaxies and our LOFAR study of the nearby starburst dwarf irregular galaxy IC 10. We explore the relation of RC emission with star formation tracers and study in IC 10 the nature of a low-frequency radio halo, which we find to be the result of a galactic wind.

scholarly journals The Extended GMRT Radio Halo Survey

2013 ◽  
Vol 557 ◽  
pp. A99 ◽  
Author(s):  
R. Kale ◽  
T. Venturi ◽  
S. Giacintucci ◽  
D. Dallacasa ◽  
R. Cassano ◽  
...  
Keyword(s):  
Radio Halo

scholarly journals Magnetic Fields in Disks and Halos of Spiral Galaxies

1991 ◽  
Vol 144 ◽  
pp. 267-280 ◽  
Author(s):  
Rainer Beck
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Spiral Galaxies ◽  
Coronal Holes ◽  
Azimuthal Angle ◽  
Total Strength ◽  
Radio Halo ◽  
Star Formation Activity ◽  
Energy Equipartition ◽  
Field Lines

Spiral galaxies host interstellar magnetic fields of 4-15 μG total strength. A significant fraction of the field lines shows large-scale structures. At face-on or moderately inclined view, the field lines run generally parallel to the spiral arms, either with uniform direction with respect to azimuthal angle (axisymmetric spiral, ASS), with one reversal along azimuthal angle (bisymmetric spiral, BSS), or with spiral orientation without dominating direction.At edge-on view, the field is concentrated in a thin disk, often surrounded by a thick radio disk with field lines mostly parallel to the plane, similar to the quadrupole-type dynamo field. Radio polarization data from NGC891 indicate that the thermal gas seen in Hα is responsible for Faraday depolarization. The required scaleheight of the field of ~4 kpc is comparable to the value expected in case of energy equipartition between magnetic fields and cosmic rays. The interacting edge-on galaxy NGC 4631 shows a much larger radio halo with field lines perpendicular to the disk, possibly driven by a strong galactic wind or the result of a dipole-type halo field.Field lines bending out of the plane are also visible in face-on galaxies as regions with high rotation measures and low star-formation activity. The resemblance to the phenomenon of the solar corona suggests to call them “galactic coronal holes”.

scholarly journals Internal dynamics of the radio halo cluster Abell 773: a multiwavelength analysis

2007 ◽  
Vol 467 (1) ◽  
pp. 37-48 ◽  
Author(s):  
R. Barrena ◽  
W. Boschin ◽  
M. Girardi ◽  
M. Spolaor
Keyword(s):  
Internal Dynamics ◽  
Radio Halo

scholarly journals THE DISCOVERY OF A RADIO HALO IN PLCK G147.3–16.6 AT Z = 0.65

2014 ◽  
Vol 781 (2) ◽  
pp. L32 ◽  
Author(s):  
R. J. van Weeren ◽  
H. T. Intema ◽  
D. V. Lal ◽  
A. Bonafede ◽  
C. Jones ◽  
...  
Keyword(s):  
Radio Halo

scholarly journals Loop I (the north Polar Spur) region - a quasi radio halo

1985 ◽  
Vol 106 ◽  
pp. 245-246
Author(s):  
Jelena Milogradov-Tuin
Keyword(s):  
Central Region ◽  
Spectral Indices ◽  
Radio Halo ◽  
The North ◽  
North Polar ◽  
Image Position

The distribution of total spectral indices between 38 and 408 MHz with a resolution of for δ>-25° has the following main properties:1. Relatively small variations of spectral indices over the sky.2. High indices in the central region at high galactic latitudes.3. Moderately low spectral indices in the anticentre region.4. Lower indices in the low-brightness regions (cold holes).5. The lowest indices in regions containing large amounts of HII.

On the origin of the radio halo in the coma cluster of galaxies

1990 ◽  
Vol 105 (8-9) ◽  
pp. 845-856
Author(s):  
Kwang-Tae Kim
Keyword(s):  
Coma Cluster ◽  
Radio Halo ◽  
Cluster Of Galaxies

The Ionized Gas and Radio Halo of NGC 3432 (ARP 206)

1997 ◽  
Vol 113 ◽  
pp. 2006 ◽  
Author(s):  
Jayanne English ◽  
Judith A. Irwin
Keyword(s):  
Ionized Gas ◽  
Radio Halo

Radio and X-ray observations of the radio halo source in A1367

1983 ◽  
Vol 270 ◽  
pp. 410 ◽  
Author(s):  
G. Gavazzi ◽  
G. Trinchieri
Keyword(s):  
X Ray ◽  
Radio Halo

scholarly journals A spectroscopic survey of Abell 1703: is it a rare relaxed cluster hosting a radio halo or a usual merging system?

2020 ◽  
Vol 492 (2) ◽  
pp. 2405-2417 ◽  
Author(s):  
W Boschin ◽  
M Girardi ◽  
F Gastaldello
Keyword(s):  
Gravitational Lensing ◽  
Statistical Tests ◽  
Galaxy Cluster ◽  
Theoretical Models ◽  
Sloan Digital Sky Survey ◽  
Cluster Galaxies ◽  
Radio Halo ◽  
Sky Survey ◽  
Galaxies Kinematics ◽  
First Moment

ABSTRACT We present the study of the internal dynamics of the intriguing galaxy cluster Abell 1703, a system hosting a probable giant radio halo whose dynamical status is still controversial. Our analysis is based on unpublished spectroscopic data acquired at the Italian Telescopio Nazionale Galileo and data publicly available in the literature. We also use photometric data from the Sloan Digital Sky Survey. We select 147 cluster members and compute the cluster redshift 〈z〉 ∼ 0.277 and the global line-of-sight velocity dispersion σv ∼ 1300 km s−1. We infer that Abell 1703 is a massive cluster: M200 ∼ 1–2 × 1015 M⊙. The results of our study disagree with the picture of an unimodal, relaxed cluster as suggested by previous studies based on the gravitational lensing analysis and support the view of a perturbed dynamics proposed by recent works based on Chandra X-ray data. The first strong evidence of a dynamically disturbed cluster comes from the peculiarity of the BCG velocity with respect to the first moment of the velocity distribution of member galaxies. Moreover, several statistical tests employed to study the cluster galaxies kinematics find significant evidence of substructure, being Abell 1703 composed by at least two or three subclumps probably caught after the core–core passage. In this observational scenario, the suspected existence of a radio halo in the centre of this cluster is not surprising and well agrees with the theoretical models describing diffuse radio sources in clusters.

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