Linear spectropolarimetric analysis of fairall 9 with VLT/FORS2

Bo-Wei Jiang,Ascensión Del Olmo,Elena Shablovinskaya,Bożena Czerny,Đorđe Savić,Paola Marziani,Victor L Afanasiev,Marzena Śniegowska,Paola Mazzei,Mauro D’Onofrio,Luka Č Popović,Jian-Min Wang,Swayamtrupta Panda

doi:10.1093/mnras/stab2273

Abstract

ABSTRACT The quasar main sequence appears to be an incredibly powerful tool to organize the diversity in large samples of type-1 quasars but the most important physical parameters governing it are still unclear. Here, we investigate the origin of the broadening and of a defining feature of Population B sources: a strong redward asymmetry of the Balmer emission lines. We focus on a prototypical source, Fairall 9. Spectropolarimetric data of the Fairall 9 broad H β and H α profiles allowed for a view of the geometric and dynamical complexity of the line emitting regions. Measurements (1) provided evidence of rotational motion; (2) were helpful to test the presence of polar and equatorial scatterers, and their association with non-virial motions. However, we suggest that the polarization properties appear to be more consistent with a warped disc geometry induced by Lense–Thirring precession.

Highlights

The quasar Main Sequence (MS) is a concept that arose from the Principal Component Analysis on 87 quasars introduced by Boroson & Green (1992)
The measured polarization properties have been used for inferring constraints on the kinematics and geometry of the broad line region (BLR) as well as on the scattering region
(ii) The polarization angle in the center of Hβ and Hα is atypical, in the sense that the "swing" shape is not as regular as the one seen in most cases by Afanasiev et al (2019), and the dynamical center may be shifted with respect to rest frame

Summary

Introduction

The quasar Main Sequence (MS) is a concept that arose from the Principal Component Analysis on 87 quasars introduced by Boroson & Green (1992). The usefulness of the MS is rooted in the ability to contextualize every quasar as part of a sequence (Sulentic et al 2000a; Shen & Ho 2014). Most notable correlations involve the width and shape of the Balmer line profiles, the strength of optical Fe emission and the amplitude of the systematic blueshifts of high-ionization lines with respect to the quasars rest frame (see e.g., Fraix-Burnet et al 2017, for a summary). The Eigenvector 1 (E1)related correlations allowed for the identification of two main quasar populations along the MS: Population A (Pop. A) with FWHM(Hβ) ≤ 4000 km s−1 and Population B (Pop. B) with FWHM(Hβ) > 4000 km s−1 (Sulentic et al 2000a)

Results

Discussion

Conclusion