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A rapid occultation event in NGC 3227

Turner, T. J. and Reeves, J. N. and Braito, V. and Lobban, A. and Kraemer, S. and Miller, L. (2018) A rapid occultation event in NGC 3227. Monthly Notices of the Royal Astronomical Society, 481 (2). pp. 2470-2478. ISSN 0035-8711. doi:10.1093/mnras/sty2447.

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NGC 3227 exhibits rapid flux and spectral variability in the X-ray band. To understand this behaviour, we conducted a coordinated observing campaign using 320 ks of XMM–Newton exposures together with 160 ks of overlapping NuSTAR observations, spanning a month. Here, we present a rapid variability event that occurs toward the end of the campaign. The spectral hardening event is accompanied by a change in the depth of an unresolved transition array (UTA), whose time-dependent behaviour is resolved using the RGS data. This UTA fingerprint allows us to identify this as a transit event, where a clump of gas having N_H∼5×10^(22) atoms cm^(−2 ), log ξ ∼ 2 occults ∼60 per cent of the continuum photons over the course of approximately a day. This occulting gas is likely associated with clouds in the inner broad-line region. An additional zone of gas with lower column and higher ionization, matches the outflow velocity of the variable zone, and may represent transmission through the cloud limb.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Turner, T. J.0000-0003-2971-1722
Braito, V.0000-0002-2629-4989
Lobban, A.0000-0002-6433-1357
Additional Information:© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2018 September 3. Received 2018 August 31; in original form 2018 July 23. Published: 06 September 2018. TJT acknowledges National Aeronautics and Space Administration (NASA) grant NNX17AD91G. Valentina Braito acknowledges financial support through NASA grant NNX17AC40G and through the CSST Visiting Scientist Initiative. APL acknowledges support from Science and Technology Facilities Council (STFC) consolidated grant ST/M001040/1. We are grateful to the XMM and NuSTAR operations teams for performing this campaign and providing software and calibration for the data analysis.
Subject Keywords:galaxies: active – galaxies: individual: NGC 3227 – galaxies: Seyfert –X-rays: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20180906-154725591
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Official Citation:T J Turner, J N Reeves, V Braito, A Lobban, S Kraemer, L Miller; A rapid occultation event in NGC 3227, Monthly Notices of the Royal Astronomical Society, Volume 481, Issue 2, 1 December 2018, Pages 2470–2478,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89435
Deposited By: Joy Painter
Deposited On:06 Sep 2018 23:49
Last Modified:16 Nov 2021 00:35

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