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# Determination of the size of the dust torus in H0507+164 through optical and infrared monitoring

Mandal, Amit Kumar, Rakshit, Suvendu, Kurian, Kshama S., Stalin, C. S., Mathew, Blesson, Hoenig, Sebastian, Gandhi, Poshak, Sagar, Ram and Pandge, M. B. (2018) Determination of the size of the dust torus in H0507+164 through optical and infrared monitoring Monthly Notices of the Royal Astronomical Society

Record type: Article

## Abstract

The time delay between flux variations in different wavelength bands can be used to probe the inner regions of active galactic nuclei (AGN). Here, we present the first measurements of the time delay between optical and near-infrared (NIR) flux variations in H0507+164, a nearby Seyfert 1.5 galaxy at z = 0.018. The observations in the optical V -band and NIR J, H and Ks bands carried over 35 epochs during the period October 2016 to April 2017 were used to estimate the inner radius of the dusty torus. From a careful reduction and analysis of the data using cross-correlation techniques, we found delayed responses of the J, H and Ks light curves to the V -band light curve. In the rest frame of the source, the lags between optical and NIR bands are found to be $27.1^{+13.5}_{-12.0}$ days (V vs. J), $30.4^{+13.9}_{-12.0}$ days (V vs. H) and $34.6^{+12.1}_{-9.6}$ days (V vs. K ). The lags between the optical and different NIR bands are thus consistent with each other. The measured lags indicate that the inner edge of dust torus is located at a distance of 0.029 pc from the central UV/optical AGN continuum. This is larger than the radius of the broad line region of this object determined from spectroscopic monitoring observations thereby supporting the unification model of AGN. The location of H0507+164 in the {\tau} - MV plane indicates that our results are in excellent agreement with the now known lag-luminosity scaling relationship for dust in AGN.

Text sty200 - Accepted Manuscript

Accepted/In Press date: 22 January 2018
e-pub ahead of print date: 29 January 2018
Additional Information: 8 pages, 4 figures, accepted by MNRAS main journal
Keywords: astro-ph.GA

## Identifiers

Local EPrints ID: 417645
URI: https://eprints.soton.ac.uk/id/eprint/417645
ISSN: 0035-8711
PURE UUID: d7a7205f-fd0a-487f-bd58-3629a0e956e1
ORCID for Poshak Gandhi: orcid.org/0000-0003-3105-2615

## Catalogue record

Date deposited: 08 Feb 2018 17:30

## Contributors

Author: Amit Kumar Mandal
Author: Suvendu Rakshit
Author: Kshama S. Kurian
Author: C. S. Stalin
Author: Blesson Mathew
Author: Sebastian Hoenig
Author: Poshak Gandhi
Author: Ram Sagar
Author: M. B. Pandge

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