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

M. L. Parker, D. R. Wilkins, A. C. Fabian, D. Grupe, T. Dauser, G. Matt, F. A. Harrison, L. Brenneman, S. E. Boggs, Finn Erland Christensen, W. W. Craig, L. C. Gallo, C. J. Hailey, E. Kara, S. Komossa, A. Marinucci, J. M. Miller, G. Risaliti, D. Stern, D. J. WaltonW. W. Zhang

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    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 similar to 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 3 sigma 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.
    Original languageEnglish
    JournalMonthly Notices of the Royal Astronomical Society
    Volume443
    Issue number2
    Pages (from-to)1723-1732
    Number of pages10
    ISSN0035-8711
    DOIs
    Publication statusPublished - 2014

    Bibliographical note

    © 2014 The Authors
    Published by Oxford University Press on behalf of the Royal Astronomical Society

    Keywords

    • ASTRONOMY
    • ACTIVE GALACTIC NUCLEI
    • X-RAY REFLECTION
    • ACCRETING BLACK-HOLES
    • XMM-NEWTON
    • FLUX STATE
    • LONG HARD
    • NGC 4051
    • IRAS 13224-3809
    • EMISSION-LINES
    • 1H 0707-495
    • galaxies: active
    • galaxies: individual: Mrk 335
    • galaxies: Seyfert

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