VEGAS: A VST Early-type Galaxy Survey. III. Mapping the Galaxy Structure, Interactions, and Intragroup Light in the NGC 5018 Group

Abstract

Most of the galaxies in the Universe at present day are in groups, which are key to understanding the galaxy evolution. In this work we present a new deep mosaic of 1.2 × 1.0 square degrees of the group of galaxies centered on NGC 5018, acquired at the ESO VLT Survey Telescope. We use u, g, r images to analyse the structure of the group members and to estimate the intra-group light. Taking advantage of the deep and multiband photometry and of the large field of view of the VST telescope, we studied the structure of the galaxy members and the faint features into the intra-group space and we give an estimate of the intragroup diffuse light in the NGC 5018 group of galaxies. We found that ∼ 41% of the total g-band luminosity of the group is in the form of intragroup light (IGL). The IGL has a (g -r) color consistent with those of other galaxies in the group, indicating that the stripping Corresponding author: Marilena Spavone marilena.spavone@oacn.inaf.it arXiv:1807.11204v1 [astro-ph.GA] 30 Jul 2018 2 Spavone et al.leading to the formation of IGL is ongoing. From the study of this group we can infer that there are at least two different interactions involving the group members: one between NGC 5018 and NGC 5022, which generates the tails and ring-like structures detected in the light, and another between NGC 5022 and MCG-03-34-013 that have produced the HI tail. A minor merging event also happened in the formation history of NGC 5018 that have perturbed the inner structure of this galaxy.

High‐resolution morphology and surface photometry of KIG 685 and KIG 895 with ARGOS+LUCI using the Large Binocular Telescope

“…However, the accurate PSF deconvolution they applied indicates that the broadening takes effect at surface brightness levels fainter than μ r = 25 mag arcsec −2 (see their Figure 12). Results similar to Trujillo & Fliri () for the Gran Telescopio de Canarias+OSIRIS camera have been obtained by Spavone et al () and Cattapan et al () using VST + OmegaCam at ESO. We need to consider two facts.…”

“…Very deep optical observations (e.g., Cattapan et al ; Spavone et al ; Trujillo & Fliri ) reaches surface brightness levels below 29–30 mag arcsec −2 in the r SDSS band. The detailed study by Trujillo & Fliri () showed that galaxies may be broadened in their outskirts by the PSF wings that scatter light.…”

“…PSF are wavelength dependent and vary with time (Sandin , ). Extended PSFs have been used in very deep optical photometry (e.g., Cattapan et al ; Spavone et al ; Trujillo & Fliri ).…”

Structure of Brightest Cluster Galaxies and Intracluster Light

“…These relics of violent accretion have been predicted by numerical simulations as the most direct evidence for hierarchical clustering (Bullock & Johnston 2005;Johnston et al 2008;Rudick et al 2009;Cooper et al 2010;Puchwein et al 2010;Cooper et al 2013;Rodriguez-Gomez et al 2016;Harris et al 2017). They have been discovered around local late-type galaxies (e.g., Martínez-Delgado et al 2010;Chonis et al 2011;Ibata et al 2014;Foster et al 2014;Amorisco et al 2015;Merritt et al 2016) and local early-type galaxies (Tal et al 2009;Duc et al 2015;Bílek et al 2016;Crnojević et al 2016) as well as galaxy groups (Da Rocha et al 2006;Watkins et al 2014Watkins et al , 2015Okamoto et al 2015;Spavone et al 2018) and galaxy clusters (Feldmeier et al 2002;Arnaboldi et al 2012;Mihos et al 2017;Iodice et al 2016Iodice et al , 2017Iodice et al , 2018. A review on the topic can be found in Carlin et al (2016).…”

“…These unbound stars then virialize in the cluster and add up to the ICL budget. For instance, unprecedentedly deep photometric surveys of the Virgo (Mihos et al 2017) and Fornax clusters (Iodice et al 2016(Iodice et al , 2017(Iodice et al , 2018 have unveiled multitudes of tidal streams. Other examples have been discovered in the Coma and Centaurus Clusters (Gregg & West 1998;Trentham & Mobasher 1998;Calcáneo-Roldán et al 2000).…”