Assigned ID: 218 ----- Attempting Submission 1 (Thu Feb 23 21:15:34 GMT 2012) ----- Our group at Colorado has produced an AGN composite spectrum, using a pilot sample of 22 bright AGN observed by the Cosmic Origins Spectrograph (COS), probing the rest-frame FUV and EUV, for targets between z = 0.026 and z = 1.44. Of these 22 AGN, only 8 were at sufficient redshift to measure the rest-frame continuum below 912 A. We will now analyze archival spectra of 100-150 AGN covering the rest-frame EUV (600-900 A) and 10-40 AGN that cover even shorter wavelengths (300-600 A). The resulting composite spectrum will provide a dramatic improvement over our pilot study. We also expect this composite to identify and characterize key emission lines in the EUV, such as Ne VIII, O III, O IV, and O V, whose line strengths will provide new diagnostics of the broad emission-line regions of quasars. Our full composite AGN spectrum will span 300-1800 A, using a significant number of COS spectra of AGN, with a variety of types and luminosities. These Lyman continuum photons are responsible for ionizing hydrogen, helium, and metal ions, and for the heating of the diffuse intergalactic medium. Characterizing the AGN spectrum in the far-UV and ionizing EUV is a crucial ingredient for studies of quasars and the IGM. AGN/QUASARS 12 Medium false 0.0 0.0 false false false false SUPPORTED