VEGAS: A VST Early-type GAlaxy Survey.VI. The diffuse light in HCG 86 from the ultra-deep VEGAS images
Rossella Ragusa, Marilena Spavone, Enrichetta Iodice, Sarah Brough, Maria Angela Raj, Maurizio Paolillo, Michele Cantiello, Duncan A. Forbes, Antonio La Marca, … 展开作者
Rossella Ragusa, Marilena Spavone, Enrichetta Iodice, Sarah Brough, Maria Angela Raj, Maurizio Paolillo, Michele Cantiello, Duncan A. Forbes, Antonio La Marca, Giuseppe D Ago, Roberto Rampazzo, Pietro Schipani
Context. In this paper we present ultra deep images of the compact group of galaxies HCG 86 as part of the VEGAS survey. Aims. Our main goals are to estimate the amount of intragroup light (IGL), to study the light and color distributions in order to address the main formation process of the IGL component in groups of galaxies. Methods. We derived the azimuthally averaged surface brightness profiles in the g,r and i bands with g - r and r - i average colors and color profiles for all group members. By fitting the light distribution, we have extrapolated the contribution of the stellar halos plus the diffuse light from the brightest component of each galaxy. The results are compared with theoretical predictions. Results. The long integration time and wide area covered make our data deeper than previous literature studies of the IGL in compact groups of galaxies and allow us to produce an extended (~160 kpc) map of the IGL, down to a surface brightness level of about 30 mag/arcsec^2 in the g band. The IGL in HCG 86 is mainly in diffuse form and has average colors of g - r ~ 0.8 mag and r - i ~ 0.4 mag. The fraction of IGL in HCG 86 is ~ 16% of the total luminosity of the group, and this is consistent with estimates available for other compact groups and loose groups of galaxies of similar virial masses. A weak trend is present between the amount of IGL and the early-type to late-type galaxy ratio. Conclusions. By comparing the IGL fraction and colors with those predicted by simulations, the amount of IGL in HCG 86 would be the result of the disruption of satellites at an epoch of z ~ 0.4. At this redshift, observed colors are consistent with the scenario where the main contribution to the mass of the IGL comes from the intermediate-massive galaxies.
We present the VST Early-type GAlaxy Survey (VEGAS), which is designed to obtain deep multiband photometry in g, r, i, of about one hundred nearby galaxies down to 27.3, 26.8, and 26 mag/arcsec^2 respectively, using the ESO facility VST/OmegaCAM. The goals of the survey are 1) to map the light distribution up to ten effective radii, r_e, 2) to trace color gradients and surface brightness fluctuation gradients out to a few r_e for stellar population characterization, and 3) to obtain a full census of the satellite systems (globular clusters and dwarf galaxies) out to 20% of the galaxy virial ra…
We present the first data release (DR1) of the VST Early-type GAlaxy Survey (VEGAS). This is a deep multi-band (u'g'r'i') imaging survey, carried out with the ESO VLT Survey Telescope (VST). To date, using about 90% of the total observing time, VEGAS has already collected 43 targets (groups and clusters of galaxies) covering a total area on the sky of about 95 square degrees. Taking advantage of the wide (1 deg^2) field-of-view of OmegaCAM@VST, the long integration time and the wide variety of targets, VEGAS has proven to be a gold mine to explore the structure of galaxies down to the faintest…
Observations of diffuse starlight in the outskirts of galaxies are thought to be a fundamental source of constraints on the cosmological context of galaxy assembly in the $Λ$CDM model. Such observations are not trivial because of the extreme faintness of such regions. In this work, we investigate the photometric properties of six massive early type galaxies (ETGs) in the VEGAS sample (NGC 1399, NGC 3923, NGC 4365, NGC 4472, NGC 5044, and NGC 5846) out to extremely low surface brightness levels, with the goal of characterizing the global structure of their light profiles for comparison to state…
The VST Early-type GAlaxy Survey (VEGAS) is a deep, multi-band (u, g, r, i) imaging survey, carried out with the 2.6-metre VLT Survey Telescope (VST) at ESO's Paranal Observatory in Chile. VEGAS combines the wide (1-square-degree) OmegaCAM imager and long integration times, together with a specially designed observing strategy. It has proven to be a gold mine for studies of features at very low surface brightness, down to levels of mu_g~27-30 magnitudes arcsec^(-2), over 5-8 magnitudes fainter than the dark sky at Paranal. In this article we highlight the main science results obtained with VEG…
This paper is based on the multi-band VST Early-type GAlaxy Survey (VEGAS) with the VLT Survey Telescope (VST). We present new deep photometry of the IC1459 group in g and r band. The main goal of this work is to investigate the photometric properties of the IC1459 group, and to compare our results with those obtained for other galaxy groups studied in VEGAS, in order to provide a first view of the variation of their properties as a function of the evolution of the system. For all galaxies in the IC1459 group, we fit isophotes and extract the azimuthally-averaged surface-brightness profiles, t…
This paper focuses on NGC 1533 and the pair IC 2038 and IC 2039 in Dorado a nearby, clumpy, still un-virialized group. We obtained their surface photometry from deep OmegaCAM@ESO-VST images in g and r bands. For NGC 1533, we map the surface brightness down to $μ_g \simeq 30.11$ mag/arcsec$^{2}$ and $μ_r \simeq 28.87$ mag/arcsec$^{2}$ and out to about $4R_e$. At such faint levels the structure of NGC 1533 appear amazingly disturbed with clear structural asymmetry between inner and outer isophotes in the North-East direction. We detect new spiral arm-like tails in the outskirts, which might like…
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 x 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 giv…
We present a study of globular clusters (GCs) and other small stellar systems (SSSs) in the field of NGC3115, observed as part of the VEGAS imaging survey, carried out with the VST telescope. We use deep g and i data of NGC3115, a well-studied lenticular galaxy with excellent scientific literature. This is fundamental to test the methodologies, verify the results, and probe the capabilities of the VEGAS-SSS. Leveraging the large field of view of the VST allow us to accurately study of the distribution and properties of SSSs as a function of galactocentric distance Rgc, well beyond ~20 galaxy e…
The VST-VEGAS project is aimed at observing and studying a rich sample of nearby early-type galaxies in order to systematically characterize their properties over a wide baseline of sizes and out to the faint outskirts where data are rather scarce so far. The external regions of galaxies more easily retain signatures about the formation and evolution mechanisms which shaped them, as their relaxation time are longer, and they are more weakly influenced by processes such as mergers, secular evolution, central black hole activity, and supernova feedback on the ISM, which tend to level age and met…
In this paper we present the deep, wide-field and multi-band imaging of the LEO I pair NGC~3379-NGC~3384, from the VST Early-type GAlaxy Survey (VEGAS). The main goal of this study is to map the intra-group baryons in the pair, in the form of diffuse light and globular clusters (GCs). Taking advantage from the large covered area, which extends for $\sim$ 3.9 square degrees around the pair, and the long integration time, we can map the light distribution out to $\sim$ 63 kpc and down to $\sim$ 30 mag/arcsec$^2$ in the $g$ band and $\sim$ 29 mag/arcsec$^2$ in the $r$ band, deeper than previous d…
In this paper we report on the discovery of 27 low-surface brightness galaxies, of which 12 are candidate ultra-diffuse galaxy (UDG) in the Hydra I cluster, based on deep observations taken as part of the VST Early-type Galaxy Survey (VEGAS). This first sample of UDG candidates in the Hydra I cluster represents an important step in our project that aims to enlarge the number of confirmed UDGs and, through study of statistically relevant samples, constrain the nature and formation of UDGs. This study presents the main properties of this class of galaxies in the Hydra I cluster. For all UDGs, we…
In this Letter we revisit the relationship between the fraction of the intra-cluster light (ICL) and both the virial mass and the fraction of Early Type Galaxies in the host halo. This is based on a statistically significant and homogeneous sample of 22 groups and clusters of galaxies in the local Universe ($z \leq 0.05$), obtained with the VST Early-type GAlaxy Survey (VEGAS). Taking advantage of the long integration time and large area of the VEGAS images, we are able to map the galaxy outskirts and ICL down to $μ_g$ $\geq$ 29-30 mag/arcsec$^2$ and out to hundreds of kpc. With this data-set,…
We analyze the globular cluster (GC) systems in two very different galaxies, N3115 and N1399. With the papers of this series, we aim at highlighting common and different properties in the GC systems in galaxies covering a wide range of parameter space. We compare the GCs in N3115 and N1399 as derived from the analysis of u, g, and i band images taken with the VST telescope as part of the VEGAS and FDS surveys. We selected GC candidates using as reference the morpho-photometric and color properties of confirmed GCs. The surface density of GCs in N3115 reveal a morphology similar to the profile …
In this paper we present the new deep images from the VEGAS survey of three massive ($M_{*} \simeq 10^{12}$~M$_\odot$) galaxies from the MUSE Most Massive Galaxies (M3G) project, with distances in the range $151\leq D \leq 183$ Mpc: PGC007748, PGC015524 and PGC049940. The long integration time and the wide field of view of OmegaCam@VST allowed us to map the light and color distributions down to $μ_g\simeq30$~mag/arcsec$^2$ and out to $\sim 2R_e$. The deep data are crucial to estimate the contribution of the different galaxy's components, in particular the accreted fraction in the stellar halo.…
The VST Photometric Halpha Survey of the Southern Galactic Plane and Bulge (VPHAS+) is surveying the southern Milky Way in u, g, r, i and Halpha at 1 arcsec angular resolution. Its footprint spans the Galactic latitude range -5 < b < +5 at all longitudes south of the celestial equator. Extensions around the Galactic Centre to Galactic latitudes +/-10 bring in much of the Galactic Bulge. This ESO public survey, begun on 28th December 2011, reaches down to 20th magnitude (10-sigma) and will provide single-epoch digital optical photometry for around 300 million stars. The observing strategy and d…
In this work, we extend the catalog of low-surface brightness (LSB) galaxies, including Ultra-Diffuse Galaxy (UDG) candidates, within $\approx 0.4R_{vir}$ of the Hydra I cluster of galaxies, based on deep images from the VST Early-type GAlaxy Survey (VEGAS). The new galaxies are found by applying an automatic detection tool and carrying out additional visual inspections of $g$ and $r$ band images. This led to the detection of 11 UDGs and 8 more LSB galaxies. For all of them, the cluster membership has been assessed using the color-magnitude relation derived for early-type giant and dwarf galax…
Advancing the detection of low surface brightness galaxies. I. ATTILA: multi-tAsking deTecTIon tool for Lsb gAlaxies
Universidad de La Serena（拉塞雷纳大学）；INAF-Osservatorio Astronomico di Capodimonte（意大利国家天体物理研究所卡波迪蒙特天文台）；Università di Padova（帕多瓦大学）；INAF-Osservatorio Astronomico di Padova（意大利国家天体物理研究所帕多瓦天文台）；INAF–Osservatorio Astronomico d’Abruzzo（意大利国家天体物理研究所阿布鲁佐天文台）
We present the first data release of the Fornax Deep Survey (FDS), an imaging survey using using the wide-field imager OmegaCAM mounted on the VST in the SDSS u', g', r', and i'-bands covering the Fornax Galaxy Cluster and the infalling Fornax A Group. FDS is a joint project between NOVA (previously called FOCUS - PI: R. F. Peletier) and INAF (as part of VEGAS - PIs: M. Capaccioli and E. Iodice). With exposure times of about 9 hours over an area of ~28 square degrees, this survey is a legacy dataset for studies of members of the Fornax Galaxy Cluster and the infalling Fornax A Group down to a …
