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Paper: Chapter 30: Crossmatching Data in the VO: BCG Line Ratios
Volume: 382, The National Virtual Observatory: Tools and Techniques for Astronomical Research
Page: 313
Authors: Miller, C.J.; Krughoff, K.S.
Abstract: In this chapter, we will determine the emission line ratios of Brightest Cluster Galaxies (BCGs) in a sample drawn the Sloan Digital Sky Survey C4 galaxy cluster catalog (Miller et al. 2005). These line ratios can be used to provide some insight on whether these galaxies are star-forming or contain an Active Galactic Nucleus. We will utilize a series of VO tools: Open SkyPortal, TOPCAT and VOPlot.

BCGs can be defined in different ways and are often synonymous with brightest central galaxies or even cD galaxies (galaxies with optically extended light envelopes). BCGs are the most massive galaxies and their formation and evolution are a popular and current research topic (Linden et al. 2006, Bernardi et al. 2006, Lauer et al. 2006). They have been studied for some time (Sandage 1972, Ostriker & Tremain 1975, White 1976, Thuan & Romanishin 1981, Merritt 1985, Postman and Lauer 1995, among many others).

In this VO research example, our aim is to take a list of galaxies known to lie within the footprint of the SDSS, which provides us with the possibility that some of these galaxies will have measured spectra from the SDSS spectroscopic pipeline. Thus, there is some prerequisite knowledge: 1) Many bright SDSS galaxies have spectra with measured emission line properties; 2) Our catalog of Brightest Cluster Galaxies has some overlap with the SDSS footprint. Taken together, we can crossmatch our catalog to the SDSS spectroscopic galaxy data in order to extract any available emission-line information.

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