A VLA radio-survey of early-type galaxies in the Virgo cluster - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate

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Abstract: We present the results of a 8.4 GHz Very Large Array radio survey ofearly-type galaxies extracted from the ACS Virgo Cluster Survey. The aim ofthis survey is to investigate the origin of radio emission in early-typegalaxies and its link with the host properties in an unexplored territorytoward the lowest levels of both radio and optical luminosities. Radio images,available for all 63 galaxies with BT < 14.4, show the presence of a compactradio source in 12 objects, with fluxes spanning from 0.13 to 2700 mJy. Theremaining 51 galaxies, undetected at a flux limit of ~0.1 mJy, have radioluminosities L < 4 10E18 W-Hz . The fraction of radio-detected galaxies are astrong function of stellar mass, in agreement with previous results: none ofthe 30 galaxies with stellar mass Mstar < 1.7 10E10 Msun is detected, while8 of the 11 most massive galaxies have radio cores. There appears to be nosimple relation between the presence of a stellar nucleus and radio emission. Amultiwavelength analysis of the active galactic nucleus AGN emission,combining radio and X-ray data, confirms the link between optical surfacebrightness profile and radio loudness in the sense that the bright coregalaxies are associated with radio-loud AGNs, while non-core galaxies hostradio-quiet AGNs. Not all radio-detected galaxies have a X-ray nuclear counterpart and vice-versa. A complete census of AGNs and supermassive black holes,SMBHs thus requires observations, at least, in both bands. Nonetheless, thereare massive galaxies in the sample, expected to host a large SMBH MBH ~ 10E8Msun, whose nuclear emission eludes detection despite their proximity andthe depth and the spatial resolution of the available observations. Most likelythis is due to an extremely low level of accretion onto the central SMBH.

Author: Alessandro Capetti 1, Preeti Kharb 2, David J. Axon 2, David Merritt 2, Ranieri D. Baldi 3 1INAF - Osservatorio Astronomico di To

Source: https://arxiv.org/

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