2010A&A...514A..76M


C.D.S. - SIMBAD4 rel 1.7 - 2021.06.20CEST06:38:13

2010A&A...514A..76M - Astronomy and Astrophysics, volume 514, A76-76 (2010/5-1)

GMRT observations of the Ophiuchus galaxy cluster.

MURGIA M., ECKERT D., GOVONI F., FERRARI C., PANDEY-POMMIER M., NEVALAINEN J. and PALTANI S.

Abstract (from CDS):

Observations with the Very Large Array telescope at 1477MHz revealed the presence of a radio mini-halo surrounding the faint central point-like radio source in the Ophiuchus cluster of galaxies. In this work we present a study of the radio emission from this cluster of galaxies at lower radio frequencies. We observed the Ophiuchus cluster at 153, 240, and 614MHz with the Giant Metrewave Radio Telescope. The mini-halo is clearly detected at 153 and 240MHz, the frequencies at which we reached the best sensitivity to the low-surface brightness diffuse emission, while it is not detected at 610MHz because of the too low signal-to-noise ratio at this frequency. The most prominent feature at low frequencies is a patch of diffuse steep spectrum emission located at about 5' south-east from the cluster centre. By combining these images with that at 1477MHz, we derived the spectral index of the mini-halo. Globally, the mini-halo has a low-frequency spectral index of α240153≃1.4±0.3 and an high-frequency spectral index of α1477240≃1.60±0.05. Moreover, we measure a systematic increase of the high-frequency spectral index with radius: the azimuthal radial average of α1477240 increases from about 1.3, at the cluster centre, up to about 2.0 in the mini-halo outskirts. The observed radio spectral index agrees with that obtained by modelling the non-thermal hard X-ray emission in this cluster of galaxies. We assume that the X-ray component arises from inverse-Compton scattering between the photons of the cosmic microwave background and a population of non-thermal electrons, which are isotropically distributed and whose energy spectrum is a power law with an index p. We derive that the electrons energy spectrum should extend from a minimum Lorentz factor of γmin≲700 up to a maximum Lorentz factor of γmax≃3.8x104 with an index p=3.8±0.4. The volume-averaged strength for a completely disordered intra-cluster magnetic field is BV≃0.3±0.1µG.

Abstract Copyright:

Journal keyword(s): galaxies: clusters: individual: Ophiuchus - radio continuum: galaxies

Simbad objects: 10

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Number of rows : 10

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 ACO 426 ClG 03 19 47.2 +41 30 47           ~ 2016 1
2 ACO 1367 ClG 11 44 44.6 +19 41 59           ~ 1011 1
3 3C 286 Sy1 13 31 08.2885060664 +30 30 32.960825107   17.51 17.25     ~ 3878 2
4 ClG J1347-1145 ClG 13 47 33.5 -11 45 42           ~ 491 0
5 2MASX J17115542-2309423 GiG 17 11 55.430 -23 09 42.33           ~ 13 0
6 2MASX J17120908-2328263 G 17 12 09.082 -23 28 26.32           ~ 11 0
7 NAME Oph Cluster ClG 17 12 24.7 -23 21 01           ~ 249 0
8 NAME Galactic Center gam 17 45 39.60213 -29 00 22.0000           ~ 12262 0
9 PKS 1827-36 rG 18 30 58.901 -36 02 30.33           ~ 63 1
10 QSO B1830-211 Bla 18 33 39.92 -21 03 39.9     18.70 21   ~ 573 1

    Equat.    Gal    SGal    Ecl

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2021.06.20-06:38:13

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