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Published September 11, 2014 | Submitted + Published
Journal Article Open

The NuSTAR spectrum of Mrk 335: extreme relativistic effects within two gravitational radii of the event horizon?

Abstract

We present 3–50 keV NuSTAR observations of the active galactic nuclei Mrk 335 in a very low flux state. The spectrum is dominated by very strong features at the energies of the iron line at 5–7 keV and Compton hump from 10–30 keV. The source is variable during the observation, with the variability concentrated at low energies, which suggesting either a relativistic reflection or a variable absorption scenario. In this work, we focus on the reflection interpretation, making use of new relativistic reflection models that self consistently calculate the reflection fraction, relativistic blurring and angle-dependent reflection spectrum for different coronal heights to model the spectra. We find that the spectra can be well fitted with relativistic reflection, and that the lowest flux state spectrum is described by reflection alone, suggesting the effects of extreme light-bending occurring within ∼2 gravitational radii (R_G) of the event horizon. The reflection fraction decreases sharply with increasing flux, consistent with a point source moving up to above 10 R_G as the source brightens. We constrain the spin parameter to greater than 0.9 at the 3σ confidence level. By adding a spin-dependent upper limit on the reflection fraction to our models, we demonstrate that this can be a powerful way of constraining the spin parameter, particularly in reflection dominated states. We also calculate a detailed emissivity profile for the iron line, and find that it closely matches theoretical predictions for a compact source within a few R_G of the black hole.

Additional Information

© 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2014 June 20. Received 2014 June 10; in original form 2013 October 17. First published online July 25, 2014. This work is based on observations made by the NuSTAR mission, a project led by the California Institute of Astronomy, managed by the Jet Propulsion Laboratory, and funded by NASA. This research has made use of the NUSTARDAS, jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). At Penn State Swift is supported by NASA contract NAS5-00136. MLP acknowledges financial support from the Science and Technology Facilities Council (STFC). ACF thanks the Royal Society for support. AM and GM acknowledge financial support from Italian Space Agency under grant ASI/INAF I/037/12/0-011/13. DRW is supported by a CITA National Fellowship. The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 312789.

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Published - MNRAS-2014-Parker-1723-32.pdf

Submitted - 1407.8223v1.pdf

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Additional details

Created:
August 20, 2023
Modified:
October 17, 2023