The ACS Virgo and Fornax Cluster Surveys were unprecedented surveys of early-type galaxies belonging to two benchmark clusters in the local universe, Virgo and Fornax. The surveys were based on ACS imaging from the Hubble Space Telescope (HST), and helped change the way astronomers think about galaxy formation.
Left: An intermediate-luminosity galaxy (VCC1431) in the Virgo Cluster observed with the Advanced Camera for Surveys (ACS) on HST as part of the ACS Virgo Cluster Survey, which targeted 100 early-type galaxies (Cote et al. 2004). Note the central nucleus or “luminosity excess” (see below). A similar survey of the Fornax Cluster, targeting 43 galaxies, is described in Jordan et al. (2007). Top: The ACS/WFC CCDs before the camera was assembled.
The ACS Virgo and Fornax Cluster Surveys were unprecedented surveys of early-type galaxies belonging to two benchmark clusters in the local universe, Virgo and Fornax. The surveys were based on ACS imaging from the Hubble Space Telescope (HST), and helped change the way astronomers think about galaxy formation.
The ACS Virgo and Fornax Cluster Surveys were unprecedented surveys of early-type galaxies belonging to two benchmark clusters in the local universe, Virgo and Fornax. The surveys were based on ACS imaging from the Hubble Space Telescope (HST), and helped change the way astronomers think about galaxy formation.
The ACS Virgo and Fornax cluster surveys produced more than two dozen publications on topics ranging from the core and global structure of early-type galaxies, to globular cluster systems, new families of hot stellar systems (such as “Ultra Compact Dwarf Galaxies” and “Faint Fuzzies”) and the extragalactic distance scale. Some scientific highlights and data products from the surveys include:
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The first simultaneous characterization of the central and global structure for a large sample of early-type galaxies in the nearby universe (Virgo), made possible by the large field of view of the ACS instrument on HST (Ferrarese et al. 2006a; Cote et al. 2006; Cote et al. 2007).
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The demonstration that the Sersic family of models provides a remarkably accurate description of the brightness profiles of early-type galaxies spanning nearly three orders of magnitude in luminosity (i.e., from “giant” to “dwarf” galaxies, Ferrarese et al. 2006a). These findings build upon pioneering studies by Caon et al. (1993), Graham et al. (2003), Graham & Guzman (2003) and Jerjen & Binggeli (1997).
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The finding of a systematic transition from a central luminosity “deficit” to “excess” in the central regions of galaxies, relative to the global Sersic model fit, and a dramatic upward revision of the frequency of distinct nuclear components in the centers of low- and intermediate-luminosity galaxies (Ferrarese et al. 2006a; Cote et al. 2006; Cote et al. 2007). Once again, see the series of earlier papers by Graham and collaborators, including Graham et al. (2003), Graham & Guzman (2003) and Trujillo et al. (2004), as well as Carolla et al. (1998), Boker et al. (2002, 2004), Lotz et al. (2004) and Grant et al. (2005).
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The realization that these central excesses/nuclei probably arise, for at least some galaxies, through gas inflows and starbursts expected in mergers and accretions, as had been predicted by numerical models (Cote et al. 2006, Cote et al. 2007). See also Mihos & Hernquist (1994), who anticipated these results using pioneering numerical simulations.
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The discovery that the light “excesses” (i.e., compact stellar nuclei) in the faintest galaxies contain roughly the same percentage of the total galaxy mass as do the Supermassive Black Holes (SBHs) in the brightest galaxies, suggesting a possible link between these two components (Ferrarese et al. 2006b, Cote et al. 2006). See the contemporaneous papers by Rossa et al. (2006) and Wehner and Harris (2006), and the comprehensive subsequent study by Seth et al. (2008).
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A demonstration that the early-type galaxy populations do not show a dramatic “dichotomy” in terms of their central brightness profile slopes, as was previously believed; the ACS Virgo Cluster Survey was the first study to show that the previously reported class of “power-law galaxies” actually have a two-component structure on small scales (Ferrarese et al. 2006a; Cote et al. 2007). Once again, see also Jerjen & Binggeli (1997), Graham & Guzman (2003), as well as Rest et al. (2001) and Ravindranath et al. (2001).
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A large and homogeneous catalog of more than ≈ 10,000 globular cluster candidates in early-type galaxies (Jordan et al. 2009).
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The demonstration that the fundamental properties of globular cluster systems show unexpected continuous trends with host galaxy luminosity. Specific examples include their luminosity functions, size distributions, color/metallicity distributions, and formation efficiencies (Jordan et al.2005, 2006, 2007; Peng et al. 2006a,b, 2008; Mieske et al. 2006, 2010; Sivakoff et al. 2007; Masters et al. 2010; Villegas et al. 2010). These results build upon a number of previous studies by other researchers, including Gebhardt & Kissler-Patig (1998), Larsen et al. (2001) and Kundu et al. (2001).
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The discovery of Ultra-Compact Dwarf (UCD) galaxies in the Virgo Cluster, the first measurements for the dynamical masses of these systems, and the discovery of an apparently fundamental transition between globular clusters and UCDs at ≈ 2-3 million solar masses (Hasegan et al. 2005).
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The measurement of accurate SBF distances (i.e., typical errors of ≈ 0.5 Mpc) for a large sample of galaxies in both the Virgo and Fornax Clusters, the direct measurement of the line-of-sight depth of Virgo and a precise measurement of the relative distance of the two clusters (Mei et al. 2005a,b, 2007; Blakeslee et al. 2009).
Please see the science highlights to learn more about these and other topics. To read or download individual papers, see the publications section.
The Survey Teams
The Survey Teams
The ACS Virgo and Fornax Cluster Surveys were unprecedented surveys of early-type galaxies belonging to two benchmark clusters in the local universe, Virgo and Fornax. The surveys were based on ACS imaging from the Hubble Space Telescope (HST), and helped change the way astronomers think about galaxy formation.
Program Galaxies
Left: An intermediate-luminosity galaxy (VCC1431) in the Virgo Cluster observed with the Advanced Camera for Surveys (ACS) on HST as part of the ACS Virgo Cluster Survey, which targeted 100 early-type galaxies (Cote et al. 2004). Note the central nucleus or “luminosity excess” (see below). A similar survey of the Fornax Cluster, targeting 43 galaxies, is described in Jordan et al. (2007). Top: The ACS/WFC CCDs before the camera was assembled.
The Virgo Cluster is the rich cluster nearest to the Milky Way, and the dominant mass concentration in the local universe. It also represents the nearest large collection of early-type (red sequence) galaxies within ~50 Mpc. At a distance of ≈16.5 Mpc, it has historically played a central role in furthering our understanding of galaxy evolution, supermassive black holes, the extragalactic distance scale, the intracluster medium, extragalactic star clusters, and countless other topics in modern astrophysics.
The Virgo Cluster is the rich cluster nearest to the Milky Way, and the dominant mass concentration in the local universe. It also represents the nearest large collection of early-type (red sequence) galaxies within ~50 Mpc. At a distance of ≈16.5 Mpc, it has historically played a central role in furthering our understanding of galaxy evolution, supermassive black holes, the extragalactic distance scale, the intracluster medium, extragalactic star clusters, and countless other topics in modern astrophysics.
The Fornax Cluster is smaller and more compact than Virgo. At a slightly larger distance of ≈20.0 Mpc, it offers an unique opportunity to study the fossil record of galaxy formation in rather different environment than the Virgo Cluster.
The Next Generation Virgo Cluster Survey (NGVS)
Related Surveys
NGVS team members have been played key roles in a number of past surveys of the Virgo cluster, as well as a number of ongoing or upcoming surveys. Collectively, these programs make use of both ground- and space-based telescopes, span a wide range of wavelengths, and include both blind and pointed observations. These surveys include:
The ACS Virgo and Fornax Cluster Surveys (ACSVCS, ACSFCS Virgo Redux). In two large Cycle 11 and 13 programs, the Hubble Space Telescope was used to carry out optical (F475W and F850LP) imaging of 143 early type galaxies belonging to the Virgo and Fornax clusters. A subsequent Cycle 15 Hubble program, Virgo Redux, added UV and IR imaging (F300W and F160W) for the complete sample of 100 ACSVCS program galaxies. Survey website.
GALEX Ultraviolet Virgo Cluster Survey (GUViCS). GUViCS is a complete blind survey of the Virgo cluster covering ~40 sq. deg in the far UV and ~120 sq. deg in the near UV. The central goal of the survey, which was carried out with the GALEX satellite, is a characterization of the UV properties of galaxies in a rich cluster environment, spanning a wide luminosity range from giants to dwarfs, and targeted with no prior knowledge of star formation activity. Survey website.
The Next Generation Fornax Cluster Survey (NGFS). The NGFS is using the DECam instrument on the 4m Blanco telescope to map the nearby Fornax cluster in three optical (ugi) passbands. A smaller, denser environment than Virgo, the Fornax cluster provides a southern analogue for investigating many of the same themes as the NGVS. Survey definition paper.
Mass Assembly of early-Type GaLAxies with their fine Structures (MATLAS). MATLAS investigates the mass assembly of early-type galaxies and the build-up of their scaling relations, with extremely deep optical images from CFHT/MegaCam. The sample of massive nearby galaxies is initially selected from the Atlas3D project. The targets are are located in the Local Volume (within 42 Mpc), at locations visible from the Northern hemisphere and away from the Galactic plane. Images for Atlas3D galaxies belonging to the Virgo Cluster are taken directly from the Next Generation Virgo cluster Survey. Survey website.
A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE). VESTIGE is an ongoing narrow-band imaging survey of the Virgo cluster covering ~ 100 sq. deg. aimed at studying the role of the environment on galaxy evolution. VESTIGE is a CFHT/MegaCam Large Program that will be completed in 2021; it will be the first deep, blind H-alpha survey of a nearby cluster. Project website.
Virgo Environment Traced in CO survey (VERTICO). VERTICO is an ALMA Cycle 7 Large Program to investigate the effect of environment on molecular gas by mapping the distribution and kinematics of CO(2-1) in a representative sample of 51 spiral galaxies in the Virgo cluster. This ongoing program uses Atacama Compact Array (7m + Total Power) observations for galaxies previously observed at 21cm by the VIVA survey. Project website.
Atomic gas in Virgo Interacting Dwarfs (AVID). The AVID survey was recently awarded 162.5 hours of observing time in 2021 and 2022 on the Karl G. Jansky Very Large Array to carry out 21cm HI-line mapping of low-mass galaxies in the Virgo cluster. These radio observations, which will be performed using JVLA's B, C and D array configurations, will be used to explore the combined effect of cluster-scale environment and galaxy mergers on the evolution of dwarf galaxies.
A UVIT Legacy Survey of the Virgo Cluster. Starting in 2021, the UVIT instrument onboard the Astrosat observatory will be used to carry out wide-field FUV imaging of 72 galaxies in the Virgo cluster. These Cycle A10 observations will be used to study the physics of star formation activity down to ∼100 pc scales, identify the dominant quenching mechanisms in a cluster environment and constrain the bright end of the IMF in star-forming systems.