Publication details

Very Large Array Radio Study of a Sample of Nearby X-Ray and Optically Bright Early-type Galaxies

Authors

GROSSOVÁ Romana WERNER Norbert MASSARO Francesco LAKHCHAURA Kiran PLŠEK Tomáš GABÁNYI Krisztina RAJPUROHIT Kamlesh CANNING Rebecca E. A. NULSEN Paul O'SULLIVAN Ewan ALLEN Steven W. FABIAN Andrew

Year of publication 2022
Type Article in Periodical
Magazine / Source Astrophysical Journal, Supplement Series
MU Faculty or unit

Faculty of Science

Citation
Web https://iopscience.iop.org/article/10.3847/1538-4365/ac366c
Doi http://dx.doi.org/10.3847/1538-4365/ac366c
Keywords High energy astrophysics; Active galactic nuclei; Early-type galaxies
Description Many massive early-type galaxies host central radio sources and hot X-ray atmospheres indicating the presence of radio-mechanical active galactic nucleus (AGN) feedback. The duty cycle and detailed physics of the radio-mode AGN feedback is still a matter of debate. To address these questions, we present 1-2 GHz Karl G. Jansky Very Large Array radio observations of a sample of the 42 nearest optically and X-ray brightest early-type galaxies. We detect radio emission in 41/42 galaxies. However, the galaxy without a radio source, NGC 499, has recently been detected at lower frequencies by the Low-Frequency Array. Furthermore, 27/42 galaxies in our sample host extended radio structures and 34/42 sources show environmental interactions in the form of X-ray cavities. We find a significant correlation between the radio flux density and the largest linear size of the radio emission and between the radio power and the luminosity of the central X-ray point source. The central radio spectral indices of the galaxies span a wide range of values, with the majority of the systems having steep spectra and the rest flat spectra. These results are consistent with AGN activity, where the central radio sources are mostly switched on, thus the duty cycle is very high. Seven out of 14 galaxies with pointlike radio emission (Fanaroff-Riley Class 0; FR 0) also show X-ray cavities indicating that, despite the lack of extended radio structures at 1-2 GHz, these AGNs do launch jets capable of inflating lobes and cavities.

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