The ViCTORIA project: description of a multi-frequency radio survey of the Virgo galaxy cluster

Abstract

The Virgo cluster is the closest richest nearby galaxy cluster. It is in the formation process, with a number of sub-clusters undergoing merging and interactions. Although a great laboratory to study galaxy evolution and cluster formation, its large apparent size and the severe dynamic range limitations due to the presence of the bright radio source Virgo A (M 87) reduced the ability of past wide-area radio surveys to image the region with high sensitivity and fidelity. In this paper we describe the "Virgo Cluster multi-Telescope Observations in Radio of Interacting galaxies and AGN" (ViCTORIA) project. The survey and its data reduction strategy are designed to mitigate the challenges of this field and deliver: images from 42 MHz to 1.7 GHz frequencies of the Virgo cluster, about 60 times deeper than existing data, in full polarisation, and including a blind HI survey that aims at mapping seven times more galaxies than previous experiments and without selection biases. Data have been collected with the Low-Frequency Array (LOFAR) and with MeerKAT in L-band, including polarisation and enough frequency resolution to conduct local HI studies. At the distance of Virgo, current radio instruments have the resolution to probe scales of ~500 pc and the sensitivity to study dwarf galaxies, the most fragile systems given their shallow gravitational potential wells, making Virgo a unique laboratory to study galaxy evolution and AGN feedback in a rich environment. In this work, we present some preliminary results, including high resolution images of the radio emission surrounding M 87, that show that the lobes are filled with filamentary structures. The combination of the presented radio surveys with state-of-the-art optical, UV, X-ray surveys will massively increase the scientific output from the studies of the Virgo cluster, making the ViCTORIA Project's legacy value outstanding.