Spectral optical monitoring of the double-peaked emission line AGN Arp 102B

L Č Popović,A Kovačević,A I Shapovalova,J R Valdés,D Ilić,A N Burenkov,V Patiño-Álvarez,W Kollatschny,J León-Tavares,N G Bochkarev,J Torrealba,V H Chavushyan

doi:10.1051/0004-6361/201423555

Abstract

We investigate a long-term (26 years, from 1987 to 2013) variability in the broad spectral line properties of the radio galaxy Arp 102B, an active galaxy with broad double-peaked emission lines. We use observations presented in Paper I (Shapovalova et al. 2013) in the period from 1987 to 2011, and a new set of observations performed in 2012--2013. To explore the BLR geometry, and clarify some contradictions about the nature of the BLR in Arp 102B we explore variations in the H$\alpha$ and H$\beta$ line parameters during the monitored period. We fit the broad lines with three broad Gaussian functions finding the positions and intensities of the blue and red peaks in H$\alpha$ and H$\beta$. Additionally we fit averaged line profiles with the disc model. We find that the broad line profiles are double-peaked and have not been changed significantly in shapes, beside an additional small peak that, from time to time can be seen in the blue part of the H$\alpha$ line. The positions of the blue and red peaks { have not changed significantly during the monitored period. The H$\beta$ line is broader than H$\alpha$ line in the monitored period. The disc model is able to reproduce the H$\beta$ and H$\alpha$ broad line profiles, however, observed variability in the line parameters are not in a good agreement with the emission disc hypothesis. It seems that the BLR of Arp 102B has a disc-like geometry, but the role of an outflow can also play an important role in observed variation of the broad line properties.

Highlights

Arp 102B, a low-ionization nuclear emission-line region (LINER) like object, was the first active galactic nuclei (AGN)where the broad line double-peaked profiles have been modeled with emission of an accretion disk (Chen et al 1989; Chen &Halpern 1989)
We explore variations in the Hα and Hβ line parameters during the monitored period to explore the broad-line region (BLR)
We find that the broad line profiles are double peaked and have not been changed significantly in shapes, beside an additional small peak that from time to time can be seen in the blue part of the Hα line

Summary

Introduction

Arp 102B, a low-ionization nuclear emission-line region (LINER) like object, was the first active galactic nuclei (AGN)where the broad line double-peaked profiles have been modeled with emission of an accretion disk (Chen et al 1989; Chen &Halpern 1989). Arp 102B, a low-ionization nuclear emission-line region (LINER) like object, was the first active galactic nuclei (AGN). Where the broad line double-peaked profiles have been modeled with emission of an accretion disk After that, this galaxy has been widely accepted as a prototype of an AGN with broad lines emitted from the disk Halpern 1994; Eracleous et al 1997) and has been studied intensively through different monitoring campaigns The monitoring campaigns agree that the broadline region (BLR) in Arp 102B, where the double-peaked broad emission lines are forming, seems to have a disk-like & Peterson 1990; Newman et al 1997; Sergeev et al 2000; Gezari et al 2007; Shapovalova et al 2013).

Methods

Results

Conclusion