The detection and X-ray view of the changing look AGN HE 1136-2304
Abstract
We report the detection of high-amplitude X-ray flaring of the AGN HE 1136-2304, which is accompanied by a strong increase in the flux of the broad Balmer lines, changing its Seyfert type from almost type 2 in 1993 down to 1.5 in 2014. HE 1136-2304 was detected by the XMM-Newton slew survey at >10 times the flux it had in the ROSAT all-sky survey, and confirmed with Swift follow-up after increasing in X-ray flux by a factor of 30. Optical spectroscopy with SALT shows that the AGN has changed from a Seyfert 1.95 to a Seyfert 1.5 galaxy, with greatly increased broad line emission and an increase in blue continuum AGN flux by a factor of > 4. The X-ray spectra from XMM-Newton and NuSTAR reveal moderate intrinsic absorption and a high energy cutoff at 100 keV. We consider several different physical scenarios for a flare, such as changes in obscuring material, tidal disruption events, and an increase in the accretion rate. We find that the most likely cause of the increased flux is an increase in the accretion rate, although it could also be due to a change in obscuration.
Additional Information
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 June 15. Received 2016 June 15. In original form 2016 March 5. First published online June 20, 2016. We thank the anonymous referee for their detailed and constructive feedback. We thank Lutz Wisotzki for making available the optical spectrum of HE1136-2304 taken in 1993, and we thank Vassilis Karamanavis for a careful reading of the manuscript. MLP acknowledges financial support from the Science and Technology Facilities Council (STFC). This paper is based on observations taken with the SALT telescope. This work has been supported by DFG grant Ko 857/32-2. Based on observations with XMM–Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. This work made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). We would also like to thank Neil Gehrels for approving the Swift ToO requests, and the Swift science operation team for performing the observations.Attached Files
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Additional details
- Eprint ID
- 69411
- Resolver ID
- CaltechAUTHORS:20160803-111444672
- Science and Technology Facilities Council (STFC)
- Deutsche Forschungsgemeinschaft (DFG)
- 857/32-2
- ESA Member States
- NASA/JPL/Caltech
- Created
-
2016-08-09Created from EPrint's datestamp field
- Updated
-
2021-11-11Created from EPrint's last_modified field
- Caltech groups
- Space Radiation Laboratory, NuSTAR
- Other Numbering System Name
- Space Radiation Laboratory
- Other Numbering System Identifier
- 2006.16