SPACE TELESCOPE AND OPTICAL REVERBERATION MAPPING PROJECT. I. ULTRAVIOLET OBSERVATIONS OF THE SEYFERT 1 GALAXY NGC 5548 WITH THE COSMIC ORIGINS SPECTROGRAPH ONHUBBLE SPACE TELESCOPE

Abstract

We describe the first results from a six-month long reverberation-mapping experiment in the ultraviolet based on 171 observations of the Seyfert 1 galaxy NGC 5548 with the Cosmic Origins Spectrograph on the Hubble Space Telescope. Significant correlated variability is found in the continuum and broad emission lines, with amplitudes ranging from ∼30% to a factor of two in the emission lines and a factor of three in the continuum. The variations of all the strong emission lines lag behind those of the continuum, with He II λ1640 lagging behind the continuum by ∼2.5 days and Lyα λ1215, C IV λ1550, and Si IV λ1400 lagging by ∼5-6 days. The relationship between the continuum and emission lines is complex. In particular, during the second half of the campaign, all emission-line lags increased by a factor of 1.3-2 and differences appear in the detailed structure of the continuum and emissionline light curves. Velocity-resolved cross-correlation analysis shows coherent structure in lag versus line of sight velocity for the emission lines; the high-velocity wings of C IV respond to continuum variations more rapidly than the line core, probably indicating higher velocity broad-line region clouds at smaller distances from the central

Discovery of a fast, broad, transient outflow in NGC 985

“…All observations used multiple central wavelength settings and focal-plane positions (FP-POS) to allow our merged spectra to span the gaps between the two detector segments and eliminate flat-field features and detector defects. The individual exposures were combined with updated wavelength calibrations, flat-field procedures, and flux calibrations as described by Kriss et al (2011) andDe Rosa et al (2015). The wavelength zero point was adjusted by matching the low-ionization interstellar absorption features in the spectrum to the H i velocity of v LSR = −7 km s −1 (Wakker et al 2011).…”

The Structure of the Broad-line Region in Active Galactic Nuclei. II. Dynamical Modeling of Data From the AGN10 Reverberation Mapping Campaign

“…However, with sufficiently high-quality RM data, we can actually resolve the time delays in velocity space and thus recover information about the possible phase space structure within the BLR. This velocityresolved analysis has been successfully done for several sets of data in recent years Denney et al 2010;Barth et al 2011b;Barth et al 2011a;Doroshenko et al 2012;Grier et al 2013b;De Rosa et al 2015;Du et al 2016;Pei et al 2017). In most cases, we see signatures of either gas in bound elliptical orbits or inflowing gas, although signatures of outflowing gas have also been seen (Denney et al 2009;Du et al 2016).…”

Space Telescope and Optical Reverberation Mapping Project. V. Optical Spectroscopic Campaign and Emission-line Analysis for NGC 5548

“…Concurrent with the HST program were 4 months of Swift observations and 6 months of ground-based photometric and spectroscopic observations. First results of the HST, Swift, and ground-based photometry programs were presented by De Rosa et al (2015), Edelson et al (2015), and Fausnaugh et al (2016) (Papers I-III, respectively). Goad et al (2016) (Paper IV) explore the anomalous behavior of the UV continuum and broad emission-line light curves observed during a portion of this campaign.…”