University of Hertfordshire

From the same journal

From the same journal

By the same authors

High radio-frequency properties and variability of brightest cluster galaxies

Research output: Contribution to journalArticlepeer-review


  • M.~T. Hogan
  • A.~C. Edge
  • J.~E. Geach
  • K.~J.~B. Grainge
  • J. Hlavacek-Larrondo
  • T. Hovatta
  • A. Karim
  • B.~R. McNamara
  • C. Rumsey
  • H.~R. Russell
  • P. Salomé
  • H.~D. Aller
  • M.~F. Aller
  • D.~J. Benford
  • A.~C. Fabian
  • A.~C.~S. Readhead
  • E.~M. Sadler
  • R.~D.~E. Saunders
View graph of relations
Original languageEnglish
Pages (from-to)1223-1240
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Early online date24 Aug 2015
Publication statusPublished - 21 Oct 2015


We consider the high radio-frequency (15–353 GHz) properties and variability of 35 brightest cluster galaxies (BCGs). These are the most core-dominated sources drawn from a parent sample of more than 700 X-ray selected clusters, thus allowing us to relate our results to the general population. We find that ≥6.0 per cent of our parent sample (≥15.1 per cent if only cool-core clusters are considered) contain a radio source at 150 GHz of at least 3 mJy (≈1×1023 W Hz−1 at our median redshift of z ≈ 0.13). Furthermore, ≥3.4 per cent of the BCGs in our parent sample contain a peaked component (Gigahertz Peaked Spectrum, GPS) in their spectra that peaks above 2 GHz, increasing to ≥8.5 per cent if only cool-core clusters are considered. We see little evidence for strong variability at 15 GHz on short (week–month) time-scales although we see variations greater than 20 per cent at 150 GHz over six-month time frames for 4 of the 23 sources with multi-epoch observations. Much more prevalent is long-term (year–decade time-scale) variability, with average annual amplitude variations greater than 1 per cent at 15 GHz being commonplace. There is a weak trend towards higher variability as the peak of the GPS-like component occurs at higher frequency. We demonstrate the complexity that is seen in the radio spectra of BCGs and discuss the potentially significant implications of these high-peaking components for Sunyaev–Zel‘dovich cluster searches.


This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

ID: 10175692