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Paper: Variable Galactic Nuclei Detected with the Hubble Space Telescope
Volume: 311, AGN Physics with the Sloan Digital Sky Survey
Page: 393
Authors: Sarajedini, V.L.
Abstract: We present recent results from imaging surveys with the Hubble Space Telescope WFPC2 to detect and study the properties of variable galaxy nuclei out to redshifts of ~1. Of particular interest is the nature and evolution of low-luminosity AGN (i.e., Seyferts), which become increasingly difficult to observe at high redshifts as the apparent brightness of the nuclear light becomes fainter and difficult to disentangle from the host galaxy light. Using multi-epoch HST images, we isolate and measure variability in galaxy nuclei over time periods of 5 to 7 years in the HDF-N and Groth-Westphal Survey Strip. Several of the variable galaxies are also X-ray, mid-IR and radio sources. The estimated absolute magnitudes of the varying nuclei extend as faint as MB=−15 in the redshift range 0.4 < z < 1.1. We discuss implications for the evolution of faint AGN out to these redshifts.
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