Quasar Main Sequence unfolded by 2.5D FRADO (Natural expression of Eddington ratio, black hole mass, and inclination)

Abstract

The quasar main sequence (QMS), characterized by the Eigenvector 1 (EV1), serves as a unifying framework for classifying type-1 active galactic nuclei (AGNs) based on their diverse spectral properties. Although a fully self-consistent physical interpretation has long been lacking, our physically motivated 2.5D FRADO (Failed Radiatively Accelerated Dusty Outflow) model naturally predicts that the Eddington ratio ($\dot{m}$) is the primary physical driver of the QMS, with black hole mass ($M_{\mathrm{BH}}$) and inclination ($i$) acting as secondary contributors. We employed a dense grid of FRADO simulations of the geometry and dynamics of the broad-line region (BLR), covering a representative range of $M_{\mathrm{BH}}$ and $\dot{m}$. For each simulation, we computed the full width at half maximum (FWHM) of the H$\beta$ line under different $i$. The resulting FWHM--$\dot{m}$ diagram closely resembles the characteristic trend observed in the EV1 parameter space. This establishes the role of $\dot{m}$ as the true proxy for the Fe II strength parameter ($R_{\mathrm{Fe}}$), and vice versa. Our results suggest that $\dot{m}$ can be regarded as the sole underlying physical tracer of $R_{\mathrm{Fe}}$ and should therefore scale directly with it. The $M_{\mathrm{BH}}$ accounts for the virial mass-related scatter in FWHM, while $i$ acts as a secondary driver modulating $R_{\mathrm{Fe}}$ and FWHM for a given $\dot{m}$ and $M_{\mathrm{BH}}$.

4 pages plus 2 pages of appendices, 3 figures, originally accepted for publication in A&A Letters

References in corpus (36)

• Reverberation Measurements for 17 Quasars and the Size-Mass-Luminosity Relations in Active Galactic Nuclei
• Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei. II. A Homogeneous Analysis of a Large Reverberation-Mapping Database
• Determining Central Black Hole Masses in Distant Active Galaxies and Quasars. II. Improved Optical and UV Scaling Relationships
• Spectral Energy Distributions and Multiwavelength Selection of Type 1 Quasars
• Revisiting the Unified Model of Active Galactic Nuclei
• The Low-Luminosity End of the Radius-Luminosity Relationship for Active Galactic Nuclei
• Active Galactic Nuclei: what's in a name?
• Supermassive Black Holes in Active Galactic Nuclei. II. Calibration of the M-sigma Relationship for AGNs
• Black Hole Mass and Eddington Ratio as Drivers for the Observable Properties of Radio-Loud and Radio-Quiet QSOs
• Systematic Effects in Measurement of Black Hole Masses by Emission-Line Reverberation of Active Galactic Nuclei: Eddington Ratio and Inclination
• The Lick AGN Monitoring Project: Broad-Line Region Radii and Black Hole Masses from Reverberation Mapping of Hbeta
• The diversity of quasars unified by accretion and orientation
• Eigenvector 1: An Optimal Correlation Space for Active Galactic Nuclei
• The origin of the Broad Line Region in Active Galactic Nuclei
• CIV 1549 as an Eigenvector 1 Parameter for Active Galactic Nuclei
• A Catalog of Quasar Properties from Sloan Digital Sky Survey Data Release 16
• Searching for the Physical Drivers of the Eigenvector 1 Correlation Space
• The Radius-Luminosity Relationship Depends on Optical Spectra in Active Galactic Nuclei
• Cosmic Evolution of Mass Accretion Rate and Metalicity in Active Galactic Nuclei
• Comparing and calibrating black hole mass estimators for distant active galactic nuclei
• The Black Hole Mass Scale of Classical and Pseudo Bulges in Active Galaxies
• A combined Optical and X-ray Spectra Study for Type 1 AGN. III. Broadband SED Properties
• The Lick AGN Monitoring Project 2011: Fe II Reverberation from the Outer Broad-Line Region
• A Systematic Analysis of Fe II Emission in Quasars: Evidence for Inflow to the Central Black Hole
• Supermassive black holes with high accretion rates in active galactic nuclei: II. the most luminous standard candles in the Universe
• Detailed Characterization of H_beta emission line profile in low z SDSS quasars
• The Quasar Main Sequence explained by the combination of Eddington ratio, metallicity and orientation
• Modelling of the quasar main sequence in the optical plane
• The Fundamental Plane of the Broad-line Region in Active Galactic Nuclei
• The z=0.54 LoBAL Quasar SDSS J085053.12+445122.5: I. Spectral Synthesis Analysis Reveals a Massive Outflow
• The picture of BLR in 2.5-D FRADO: Dynamics & Geometry
• Radiation pressure on dust explains the Low Ionized Broad Emission Lines in Active Galactic Nuclei
• Wavelength-resolved reverberation mapping of intermediate redshift quasars HE 0413-4031 and HE 0435-4312: Dissecting Mg II, optical Fe II, and UV Fe II emission regions
• Phylogenetic Analyses of Quasars and Galaxies
• The ${\sigma }_{\mathrm{H}\beta }$-based dimensionless accretion rate and its connection with the corona for AGN
• H$\beta$ line shape and radius-luminosity relation in 2.5D FRADO