Search

The gamma-ray emitting narrow-line Seyfert 1 galaxies are a unique class of objects that launch powerful jets from relatively lower-mass black hole systems compared to the Blazars. However, the black hole masses estimated from the total flux spectrum suffer from the projection effect, making the mass measurement highly uncertain. The polarized spectrum provides a unique view of the central engine through scattered light. We performed spectropolarimetric observations of the gamma-ray emitting narrow-line Seyfert 1 galaxy 1H0323 + 342 using SPOL/MMT. The degree of polarization and polarization angle are 0.122 |$\pm$| 0.040 per cent and 142 |$\pm$| 9 degrees, while the H |$\alpha$| line is polarized at 0.265 |$\pm$| 0.280 per cent. We decomposed the total flux spectrum and estimated broad H |$\alpha$| full width at half maximum of 1015 km s |$^{-1}$| . The polarized flux spectrum shows a broadening similar to the total flux spectrum, with a broadening ratio of 1.22. The Monte Carlo radiative transfer code 'STOKES' applied to the data provides the best fit for a small viewing angle of 9–24 deg and a small optical depth ratio between the polar and the equatorial scatters. A thick broad-line region with significant scale height can explain a similar broadening of the polarized spectrum compared to the total flux spectrum with a small viewing angle. [ABSTRACT FROM AUTHOR]

Constraining the physical conditions of the ionized media in the vicinity of an active supermassive black hole (SMBH) is crucial to understanding how these complex systems operate. Metal emission lines such as iron (Fe) are useful probes to trace the gaseous media's abundance, activity, and evolution in these accreting systems. Among these, the Feii emission has been the focus of many prior studies to investigate the energetics, kinematics, and composition of the broad-emission line region (BELR) from where these emission lines are produced. In this paper, we present the first simultaneous Feii modeling in the optical and near-infrared (NIR) regions. We use cloudy photoionization code to simulate both spectral regions in the wavelength interval 4000–12,000 Å. We compare our model predictions with the observed line flux ratios for I Zw (Zwicky) 1—a prototypical strong Feii-emitting active galactic nuclei (AGNs). This allows setting constraints on the BLR cloud density and metal content that is optimal for the production of the Feii emission, which can be extended to I Zw 1-like sources by examining a broad parameter space. We demonstrate the salient and distinct features of the Feii pseudo-continuum in the optical and NIR, giving special attention to the effect of micro-turbulence on the intensity of the Feii emission. [ABSTRACT FROM AUTHOR]

The investigation of emission line regions within active galaxies (AGNs) has a rich and extensive history, now extending to the use of AGNs and quasars as "standardizable" cosmological indicators, shedding light on the evolution of our universe. As we enter the era of advanced observatories, such as the successful launch of the JWST and the forthcoming Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST), the landscape of AGN exploration across cosmic epochs is poised for exciting advancements. In this work, we delve into recent developments in AGN variability research, anticipating the substantial influx of data facilitated by LSST. The article highlights recent strides made by the AGN Polish Consortium in their contributions to LSST. The piece emphasizes the role of quasars in cosmology, dissecting the intricacies of their calibration as standard candles. The primary focus centers on the relationship between the broad-line region size and luminosity, showcasing recent breakthroughs that enhance our comprehension of this correlation. These breakthroughs encompass a range of perspectives, including spectroscopic analyses, photoionization modeling, and collaborative investigations with other cosmological tools. The study further touches on select studies, underlining how the synergy of theoretical insights and advancements in observational capabilities has yielded deeper insights into these captivating cosmic entities. [ABSTRACT FROM AUTHOR]

Using bona-fide black hole (BH) mass estimates from reverberation mapping and the line ratio [Si  vi ] 1.963 |$\rm{\mu m}$| /Brγbroad as tracer of the AGN ionizing continuum, a novel BH-mass scaling relation of the form log(M BH) = (6.40 ± 0.17) − (1.99 ± 0.37) × log ([Si  vi ]/Brγbroad), dispersion 0.47 dex, over the BH mass interval, 106–108 M⊙ is found. Following on the geometrically thin accretion disc approximation and after surveying a basic parameter space for coronal lines production, we believe one of main drivers of the relation is the effective temperature of the disc, which is effectively sampled by the [Si  vi ] 1.963 |$\rm{\mu m}$| coronal line for the range of BH masses considered. By means of cloudy photoionization models, the observed anticorrelation appears to be formally in line with the thin disc prediction T disc ∝  M BH−1/4. [ABSTRACT FROM AUTHOR]

We report preliminary results on the analysis of the continuum and Hβ light curves of the type‐1 active galactic nucleus (AGN) NGC 5548. We notice a clear signature of shallowing in the trend between the Hβ and the continuum luminosities. We attempt the recovery of this observed Hβ emission trend as a response to large continuum flux increase using CLOUDY photoionization simulations. We explore a wide range in the physical parameters space for modeling the Hβ emission from the broad‐line region (BLR) appropriate for this source. We employ a constant density, single‐cloud model approach in this study and successfully recover the observed shallowing of the Hβ emission with respect to rising AGN continuum. With our modeling, we are able to provide the constraints on the local BLR cloud density and recover the BLR distances (from the continuum source) consistent with the Hβ reverberation mapping estimates. We further discuss the implications of the BLR covering factor and their sizes on recovering the observed trend. [ABSTRACT FROM AUTHOR]

The last few years have seen the confirmation of several trends associated with the quasar main sequence. The idea of a main sequence for quasars is relatively recent, and its full potential for the observational classification and contextualization of quasars' properties has yet to be fully exploited. The main sequence drivers are discussed in terms of the properties of extreme objects. We briefly summarize developments that constrain the viewing angle of the accretion disk in a particular class of quasars (extreme Population B, radiating at low Eddington ratio), as well as inferences on the chemical composition of the broad line emitting gas, and on the nature of radio emission along the quasar main sequence. [ABSTRACT FROM AUTHOR]

The issue of the difference between optical and UV properties of radio-quiet and radioloud (relativistically “jetted”) active galactic nuclei (AGN) is a long standing one, related to the fundamental question of why a minority of powerful AGN possess strong radio emission due to relativistic ejections. This paper examines a particular aspect: the singly-ionized iron emission in the spectral range 4400–5600 Å, where the prominent HI Hb and [OIII]ll4959,5007 lines are also observed. We present a detailed comparison of the relative intensity of FeII multiplets in the spectral types of the quasar main sequence where most jetted sources are found, and afterwards discuss radioloud narrow-line Seyfert 1 (NLSy1) nuclei with g-ray detection and with prominent FeII emission. An FeII template based on I Zw 1 provides an accurate representation of the optical FeII emission for RQ and, with some caveats, also for RL sources. CLOUDY photoionization simulations indicate that the observed spectral energy distribution can account for the modest FeII emission observed in composite radio-loud spectra. However, spectral energy differences alone cannot account for the stronger FeII emission observed in radio-quiet sources, for similar physical parameters. As for RL NLSy1s, they do not seem to behave like other RL sources, likely because of their different physical properties, that could be ultimately associated with a higher Eddington ratio. [ABSTRACT FROM AUTHOR]

In this second paper in the series, we carefully analyze the observational properties of the optical Fe ii and near-IR Ca ii triplet in active galactic nuclei (AGNs), as well as the luminosity, black hole mass, and Eddington ratio in order to define the driving mechanism behind the properties of our sample. The Ca ii shows an inverse Baldwin effect, bringing out the particular behavior of this ion with respect to the other low-ionization lines such as H β. We performed a principal component analysis, where 81.2% of the variance can be explained by the first three principal components drawn from the FWHMs, luminosity, and equivalent widths. The first principal component (PC1) is primarily driven by the combination of black hole mass and luminosity with a significance over 99.9%, which in turn is reflected in the strong correlation of the PC1 with the Eddington ratio. The observational correlations are better represented by the Eddington ratio; thus, it could be the primary mechanism behind the strong correlations observed in the Ca ii –Fe ii sample. Since calcium belongs to the α-elements, the Fe ii /Ca ii flux ratio can be used as a chemical clock for determining the metal content in AGNs and trace the evolution of the host galaxies. We confirm the de-enhancement of the ratio Fe ii /Ca ii by the Eddington ratio, suggesting a metal enrichment of the BLR in intermediate-z with respect to low-z objects. A larger sample, particularly at z > 2, is needed to confirm the present results. [ABSTRACT FROM AUTHOR]

Active galaxies form a clear pattern in the optical plane showing the correlation between the FWHM of the Hβ line and the ratio of the equivalent width (EW) of the optical Fe ii emission and the broad EW(Hβ). This pattern is frequently referred to as the quasar main sequence. In this paper, we study the UV plane showing the FWHM of Mg ii line against the ratio of the EW of UV Fe ii emission to the broad EW(Mg ii). We show that the UV plane trends are different, with the underlying strong correlation between the FWHM(Mg ii) and the EW(Mg ii). This correlation is entirely driven by the choice of the continuum used to measure the EW(Mg ii). If instead of the observationally determined continuum, we use a theoretically motivated power law extrapolated from the wide wavelength range, the behavior of the FWHM versus EW for Mg ii becomes similar to the behavior for Hβ. Such a similarity is expected since both the lines belong to the low-ionization group of emission lines and come from a similar region. We discuss the behavior of the lines in the context of the broad line region model based on the presence of dust in the accretion disk atmosphere. [ABSTRACT FROM AUTHOR]