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Published June 2019 | Accepted Version + Published
Journal Article Open

Swift, NuStar and XMM-Newton observations of the NLS1 galaxy RX J2317.8-4422 in an extreme X-ray low flux state

Abstract

We report the discovery of RX J2317.8–4422 in an extremely low X-ray flux state by the Neil Gehrels Swift observatory in 2014 April/May. In total, the low-energy X-ray emission dropped by a factor of 100. We have carried out multiwavelength follow-up observations of this narrow-line Seyfert 1 galaxy. Here we present observations with Swift, XMM–Newton, and NuSTAR in 2014 October and November and further monitoring observations by Swift from 2015 to 2018. Compared with the beginning of the Swift observations in 2005, in the November 2014 XMM–Newton and NuSTAR observations RX J2317–4422.8 dropped by a factor of about 80 in the 0.3–10 keV band. While the high-state Swift observations can be interpreted by a partial covering absorption model with a moderate absorption column density of N_H = 5.4 × 10^(22) cm^(−2) or blurred reflection, due to the dominating background at energies above 2 keV the low-state XMM–Newton data cannot distinguish between different multicomponent models and were adequately fitted with a single power-law model. We discuss various scenarios like a long-term change of the accretion rate or absorption as the cause for the strong variability seen in RX J2317.8–4422.

Additional Information

© 2019 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 (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) Accepted 2019 March 18. Received 2019 March 16; in original form 2019 January 17. We thank our referee, Chris Done, for useful comments and suggestions that improved this paper. We would like to thank Neil Gehrels and Brad Cenko for approving our Target of Opportunity (ToO) requests and the Swift team for performing the ToO observations of RX J2317–4422. We also want to thank our Morehead State University students Mason Bush, Chelsea Pruett, Sonny Ernst, and Taylor Barber for looking through the Swift data to find AGNs in low X-ray flux states. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, Caltech, under contract with the National Aeronautics and Space Administration. Based on observations obtained with XMM-Newton, an European Space Agency (ESA) science mission with instruments and contributions directly funded by ESA Member States and NASA. This research has made use of the XRT Data Analysis Software (XRTDAS) developed under the responsibility of the ASI Science Data Center (ASDC), Italy. ACF acknowledges European Research Council Advanced Grant 340442.

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Accepted Version - 1903.07689.pdf

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Additional details

Created:
August 19, 2023
Modified:
October 20, 2023