A VLA 20 and 90 centimetre radio survey of distant A-bell clusters with central cD galaxies |
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| Authors: | Joydeep Bagchi Vijay K Kapahi |
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| Institution: | (1) National Centre for Radio Astrophysics, TIFR, Poona University Campus, 411 007 Pune |
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| Abstract: | A radio survey, using the Very Large Array at 20 and 90 cm λ has been carried out in the direction of 46 distant Abell clusters
(0.1 ≲ z ≲ 0.3) dominated by a cD galaxy (clusters classified to be Bautz-Morgan I type). A radio source coincident with the
cD galaxy was detected in 16 clusters. We find that the radio luminosity function of the cD galaxies at 20cm λ, and below
the luminosityP
1.4ghz ≲ 1024.5 W Hz-1, is similar to that of brightest ellipticals in less clustered environments. Above this luminosity, the cDs seem to have
a higher probability of becoming radio sources. The effect of optical brightness on radio emission is shown to be the same
for the two classes. No significantly large population of very-steep-spectrum sources with spectral index α >1.2 (flux density
∝ frequency-α) was found to be associated with cD galaxies. A significant negative correlation is found between the radio luminosity of
the cD galaxy and the cooling-time of the intra cluster medium near the galaxy. We also present evidence that the probability
of radio emission from first-ranked galaxies is dependent upon their location relative to the geometrical centres of clusters
and thus related to the morphological class and the evolutionary state of the clusters. We argue that both these effects are
primarily caused by the dynamical evolution of these distant clusters of galaxies. |
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| Keywords: | Clusters of galaxies cD galaxies radio luminosity function cooling flows |
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