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Amit Kumar Mandal, Suvendu Rakshit, Indrani Pal, Chelliah Subramonian Stalin, Ram Sagar & Blesson Mathew

REMAP: Determination of the inner edge of the dust torus in AGN by measuring time delays
Echo Mapping of Active Galactic Nuclei

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Mots-clés : galaxies, quasars, Seyfert, réverbération

Abstract

Active galactic nuclei (AGN) are high luminosity sources powered by accretion of matter onto super-massive black holes (SMBHs) located at the centres of galaxies. According to the Unification model of AGN, the SMBH is surrounded by a broad emission line region (BLR) and a dusty torus. It is difficult to study the extent of the dusty torus as the central region of AGN is not resolvable using any conventional imaging techniques available today. Though, current IR interferometric techniques could in principle resolve the torus in nearby AGN, it is very expensive and limited to few bright and nearby AGN. A more feasible alternative to the interferometric technique to find the extent of the dusty torus in AGN is the technique of reverberation mapping (RM). REMAP (REverbertion Mapping of AGN Program) is a long term photometric monitoring program being carried out using the 2 m Himalayan Chandra Telescope (HCT) operated by the Indian Institute of Astrophysics, Bangalore, aimed at measuring the torus size in many AGN using the technique of RM. It involves accumulation of suitably long and well sampled light curves in the optical and near-infrared bands to measure the time delays between the light curves in different wavebands. These delays are used to determine the radius of the inner edge of the dust torus. REMAP was initiated in the year 2016 and since then about one hour of observing time once every five days (weather permitting) has been allocated at the HCT. Our initial sample carefully selected for this program consists of a total of 8 sources observable using the HCT. REMAP has resulted in the determination of the extent of the inner edge of the dusty torus in one AGN namely H0507+164. Data accumulation for the second source is completed and observations on the third source are going on. We will outline the motivation of this observational program, the observational strategy that is followed, the analysis procedures adopted for this work and the results obtained from this program till now.

Keywords : galaxies, active, quasars, Seyfert, reverberation

To cite this article

Amit Kumar Mandal, Suvendu Rakshit, Indrani Pal, Chelliah Subramonian Stalin, Ram Sagar & Blesson Mathew, «REMAP: Determination of the inner edge of the dust torus in AGN by measuring time delays», Bulletin de la Société Royale des Sciences de Liège [En ligne], Volume 88 - Année 2019, Actes de colloques, 2nd Belgo-Indian Network for Astronomy & Astrophysics (BINA) workshop - October 2018 - Brussels, Belgium, 158-165 URL : https://popups.uliege.be:443/0037-9565/index.php?id=8788.

About: Amit Kumar Mandal

Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Road, Bangalore 560 029, India and Indian Institute of Astrophysics, Block II, Koramangala, Bangalore 560 034, India, amitkumar@iiap.res.in

About: Suvendu Rakshit

Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Quantum, Vesilinnantie 5, 20014, Finland

About: Indrani Pal

Indian Institute of Astrophysics, Block II, Koramangala, Bangalore 560 034, India

About: Chelliah Subramonian Stalin

Indian Institute of Astrophysics, Block II, Koramangala, Bangalore 560 034, India

About: Ram Sagar

Indian Institute of Astrophysics, Block II, Koramangala, Bangalore 560 034, India

About: Blesson Mathew

Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Road, Bangalore 560 029, India