We present HST STIS observations of two extreme NLS1s, IRAS 13224-3809 and 1H 0707-495. The spectra are characterized by very blue continua, broad, strongly blueshifted high-ionization lines (including \ion{ C}{ 4} and \ion{ N}{ 5}), and narrow, symmetric intermediate- (including \ion{ C}{ 3}], \ion{ Si}{ 3}], \ion{ Al}{ 3}) and low-ionization (e.g., \ion{ Mg}{ 2}) lines centered at their rest wavelengths. The emission-line profiles suggest that the high-ionization lines are produced in a wind, and the intermediate- and low-ionization lines are produced in low-velocity gas associated with the accretion disk or base of the wind. In this paper, we present the analysis of the spectra from these two objects; in a companion paper we present photoionization analysis and a toy dynamical model for the wind. The highly asymmetric profile of \ion{ C}{ 4} suggests that it is dominated by emission from the wind, so we develop a template for the wind from the \ion{ C}{ 4} line. We model the bright emission lines in the spectra using a combination of this template, and a narrow, symmetric line centered at the rest wavelength. We also analyzed a comparison sample of HST spectra from 14 additional NLS1s, and construct a correlation matrix of emission line and continuum properties. A number of strong correlations were observed, including several involving the asymmetry of the \ion{ C}{ 4} line.
Categories: astro-ph