We present a new catalog of galaxies in the wider region of the Virgo cluster, based on the Sloan Digital Sky Survey (SDSS) Data Release 7. The Extended Virgo Cluster Catalog (EVCC) covers an area of 725 deg2 or 60.1 Mpc2. It is 5.2 times larger than the footprint of the classical Virgo Cluster Catalog (VCC) and reaches out to 3.5 times the virial radius of the Virgo cluster. We selected 1324 spectroscopically targeted galaxies with radial velocities less than 3000 km s-1. In addition, 265 galaxies that have been overlooked in the SDSS spectroscopic survey but have available redshifts in the NASA Extragalactic Database are also included. Our selection process secured a total of 1589 galaxies, 676 of which are not included in the VCC.
The certain and possible cluster members are defined by means of redshift comparison with a cluster projected infall model. We employed two independent and complementary galaxy classification schemes: the traditional morphological classification based on the visual inspection of optical images and a characterization of galaxies from their spectroscopic features. SDSS u, g, r, i, and z passband photometry of all EVCC galaxies was performed using Source Extractor. We compare the EVCC galaxies with the VCC in terms of morphology, spatial distribution, and luminosity function. The EVCC defines a comprehensive galaxy sample covering a wider range in galaxy density that is significantly different from the inner region of the Virgo cluster. It will be the foundation for forthcoming galaxy evolution studies in the extended Virgo cluster region, complementing ongoing and planned Virgo cluster surveys at various wavelengths.
We also present the large-scale structures consisting of seven galaxy filaments and one possible sheet around the Virgo cluster in SGX, SGY, SGZ three dimensions of Cartesian supergalactic coordinates using the HyperLEDA database. We exploited a large number of faint (MB< -10) galaxies in comparison with previous studies, which facilitates defining filaments more clearly. In the range of 4 h-1Mpc < SGY < 16 h-1 Mpc, six filaments are identified and they are all appear to be distributed in association with the Virgo cluster, elongating toward the Virgo cluster. Moreover, peculiar velocities of galaxies in these filaments show distinct offsets from the Hubble flow indicating their infall motion toward the Virgo cluster. This confirms that the filamentary structures are under the gravitational influence of the Virgo cluster. We also identified one filament, which is newly discovered in this study, and one sheet structure backside of the main body of the Virgo cluster in 16 h-1Mpc < SGY < 27 h-1Mpc. Two structures do not show an evident hint of their infall motion into the Virgo cluster, only following well the Hubble flow. One filament is elongated along the direction toward the NGC 5353/4 group. This filament shows a distinct offset from the Hubble flow in the NGC 5353/4 groupcentric coordinates, indicating infall motion of this filament galaxies toward the NGC 5353/4 group. One sheet structure includes galaxies in the W and M clouds as well as in the western part of the southern extension in the Virgo cluster. The filamentary structures around the Virgo cluster allow us to achieve a better understanding of large scale structure and of its influence on the build-up of the galaxy cluster at z~0.