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Date and Time of the Query: 2019-04-18 T13:26:27 PDT
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For refcode 2015MNRAS.453.1223H:
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Copyright by Royal Astronomical Society. 2015MNRAS.453.1223H High radio-frequency properties and variability of brightest cluster galaxies Hogan, M. T.; Edge, A. C.; Geach, J. E.; Grainge, K. J. B.; Hlavacek-Larrondo, J.; Hovatta, T.; Karim, A.; McNamara, B. R.; Rumsey, C.; Russell, H. R.; Salome, P.; Aller, H. D.; Aller, M. F.; Benford, D. J.; Fabian, A. C.; Readhead, A. C. S.; Sadler, E. M.; Saunders, R. D. E. Abstract. 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 (~1x10^23^ 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. Key words: galaxies: active, galaxies: clusters: general, galaxies: jets, radio continuum: galaxies
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