The Extended Virgo Cluster Catalog

Suk Kim (Chungnam National University)

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. This Extended Virgo Cluster Catalog (EVCC) covers an area of 750 deg^2 or 62.2 Mpc^2, is 5.4 times larger than the footprint of the classical Virgo Cluster Catalog (VCC) and reaches two times the virial radius of the Virgo cluster. We selected 1328 spectroscopically targeted galaxies with heliocentric radial velocities less than 3,000 km/s. In addition, 271 galaxies that have been missed in the SDSS spectroscopic survey are also added from the NED. Our selection process secured a total of 1,599 galaxies of which 862 galaxies are not included in the VCC. The certain and possible cluster members are defined by morphology and by means of redshift comparison with a cluster infall model. We employed two independent and complementary galaxy classification schemes: the traditional morphological classification bas ed on the visual inspection of optical images (i.e., primary morphology) and a characterisation of galaxies from their spectroscopic features (i.e., secondary morphology). SDSS u, g, r, i, z passband photometry of all EVCC galaxies was performed using Source Extractor. We compare the EVCC with the VCC in terms of the morphology, spatial distribution, and magnitude distribution. 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.

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