AGN STORM 2. I. First results: A Change in the Weather of Mrk 817

We present the first results from the ongoing, intensive, multiwavelength monitoring program of the luminous Seyfert 1 galaxy Mrk 817. While this active galactic nucleus was, in part, selected for its historically unobscured nature, we discovered that the X-ray spectrum is highly absorbed, and there are new blueshifted, broad, and narrow UV absorption lines, which suggest that a dust-free, ionized obscurer located at the inner broad-line region partially covers the central source. Despite the obscuration, we measure UV and optical continuum reverberation lags consistent with a centrally illuminated Shakura–Sunyaev thin accretion disk, and measure reverberation lags associated with the optical broad-line region, as expected. However, in the first 55 days of the campaign, when the obscuration was becoming most extreme, we observe a de-coupling of the UV continuum and the UV broad emission-line variability. The correlation recovered in the next 42 days of the campaign, as Mrk 817 entered a less obscured state. The short C iv and Lyα lags suggest that the accretion disk extends beyond the UV broad-line region.

Properties of Very Broad Line MgII Radio-Loud and Radio-Quiet Quasars

We perform an analysis of the properties of radio-loud (RL) and radio-quiet (RQ) quasars with MgII broad emission line (i-band magnitude ≤19.1 and z ≤1.9), selected from the parent sample of SDSS DR7 catalogue. For sources with full-width half maxima (FWHM) greater than 15,000 km s−1 (very broad line sample; VBL) we find the radio loud fraction (RLF) to be about 40%. To further investigate this result we compare the bolometric luminosity, optical continuum luminosity, black hole (BH) mass and Eddington ratios of our VBL sample of RL and RQ quasars. Our analysis shows that in our VBL sample space, RL quasars have higher luminosities and BH mass than RQ quasars. The similarity in the distribution of their covering fraction (CF) shows that there is no difference in dust distribution between VBL RL and RQ quasars and hence dust is not affecting our results. We also find that there is no correlation of RL quasar properties with optical continuum luminosity and BH mass.

Spectropolarimetry of the changing-look active galactic nucleus Mrk 1018

We have obtained new spectropolarimetric observations at visible wavelengths of the changing-look active galactic nucleus (AGN) Mrk 1018. The AGN direct spectrum shows an extremely weak continuum with faint broad Hβ and Hα emission lines. Both lines can be fit with a single very broad emission line component of full width at half maximum FWHM ≃ 7200 km s−1, with no evidence of the additional 3000 km s−1-wide component that was previously detected. While this is in agreement with line formation in a Keplerian disk, the line profile variability suggests that the broad emission line region is likely more complex. The continuum polarization of Mrk 1018 is low; it is not higher in the current faint state compared to the past bright state, confirming that dust obscuration is not the mechanism at the origin of the change of look. The polarization profile of the Hα line is asymmetric with no rotation of the polarization angle, which possibly reveals line formation in a polar outflow. Alternatively, the polarization profile may be the consequence of a time delay between the direct and the polarized light. Interestingly, the polarization signatures predicted for broad lines emitted around supermassive binary black holes are not observed.

Obscuration and Scattering in Narrow-Line Seyfert 1s

Narrow-line Seyfert 1s (NLS1s) observed at large inclinations from face-on are important for understanding this amazing AGN subclass. However, progress is slowly being made in the huntings and studies of highly obscured (EB–V ≥ 1) NLS1s. Recently, we discovered that multi-wavelength photometric and polarimetric analysis can be of great help in identifying and studying highly obscured NLS1s. This paper presents an intercomparison study of three typical highly obscured NLS1s. By joint analysis of extinction, absorption lines, and scattered AGN radiation, properties of the nucleus (disk and broad emission line regions) are measured. Physical and geometrical conditions about circum-nucleus obscuring/scattering clouds are also estimated. In addition, the host galaxies which are usually difficult to observe in such high luminosity NLS1s are also revealed in these targets. The results show that obscuration and scattering can be powerful probes to obscured NLS1s. Analogues of these obscured NLS1s are found to widely exist. In addition, they will be followed up in our future works, so as to understand the nuclei, circum-nucleus clouds, and host galaxies of NLS1s.