The nature of the torus in the heavily obscured AGN Markarian 3: an X-ray study

M. Guainazzi, G. Risaliti, H. Awaki, P. Arevalo, F. E. Bauer, S. Bianchi, S. E. Boggs, W. N. Brandt, M. Brightman, Finn Erland Christensen, W. W. Craig, K. Forster, C. J. Hailey, F. Harrison, M. Koss, A. Longinotti, C. Markwardt, A. Marinucci, G. Matt, C. S. ReynoldsC. Ricci, D. Stern, Jan Svoboda, D. Walton, W. Zhang

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Abstract

In this paper, we report the results of an X-ray monitoring campaign on the heavily obscured Seyfert galaxy, Markarian 3, carried out between the fall of 2014 and the spring of 2015 with NuSTAR, Suzaku and XMM–Newton. The hard X-ray spectrum of Markarian 3 is variable on all the time-scales probed by our campaign, down to a few days. The observed continuum variability is due to an intrinsically variable primary continuum seen in transmission through a large, but still Compton-thin column density (NH ∼ 0.8–1.1 × 1024 cm−2). If arranged in a spherical-toroidal geometry, the Compton scattering matter has an opening angle ≃66°, and is seen at a grazing angle through its upper rim (inclination angle ≃70°). We report a possible occultation event during the 2014 campaign. If the torus is constituted by a system of clouds sharing the same column density, this event allows us to constrain their number (17 ± 5) and individual column density, [≃ (4.9 ± 1.5) × 1022 cm−2]. The comparison of IR and X-ray spectroscopic results with state-of-the art ‘torus’ models suggests that at least two-thirds of the X-ray obscuring gas volume might be located within the dust sublimation radius. We report also the discovery of an ionized absorber, characterized by variable resonant absorption lines due to He- and H-like iron. This discovery lends support to the idea that moderate column density absorbers could be due to clouds evaporated at the outer surface of the torus, possibly accelerated by the radiation pressure due to the central AGN emission leaking through the patchy absorber.
Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society
Volume460
Issue number2
Pages (from-to)1954-1969
ISSN0035-8711
DOIs
Publication statusPublished - 2016

Bibliographical note

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2016 The authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

Keywords

  • Galaxies: active
  • Galaxies: Seyfert
  • X-rays: galaxies
  • X-rays: individual: Markarian 3

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