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Paper: Environment Study of AGNs at z = 0.3 to 3.0 Using the Japanese Virtual Observatory
Volume: 434, Astronomical Data Analysis Software and Systems XIX
Page: 402
Authors: Shirasaki, Y.; Ohishi, M.; Mizumoto, Y.; Takata, T.; Tanaka, M.; Yasuda, N.
Abstract: We present a science use case of Virtual Observatory, which was achieved to examine an environment of AGN up to redshift of 3.0. We used the Japanese Virtual Observatory (JVO) to obtain Subaru Suprime-Cam images around known AGNs. According to the hierarchical galaxy formation model, AGNs are expected to be found in an environment of higher galaxy density than that of typical galaxies. The current observations, however, indicate that AGNs do not reside in a particularly high density environment. We investigated ∼1000 AGNs, which is about ten times larger samples than the other studies covering the redshifts larger than 0.6. We successfully found significant excess of galaxies around AGNs at redshifts of 0.3 to 1.8. If this work was done in a classical manner, that is, raw data were retrieved from the archive through a form-based web interface in an interactive way, and the data were reduced on a low performance computer, it might take several years to finish it. Since the Virtual Observatory system is accessible through a standard interface, it is easy to query and retrieve data in an automatic way. We constructed a pipeline for retrieving the data and calculating the galaxy number density around a given coordinate. This procedure was executed in parallel on ∼10 quad core PCs, and it took only one day for obtaining the final result. Our result implies that the Virtual Observatory can be a powerful tool to do an astronomical research based on large amount of data.
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