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NuSTAR observations of Mrk 766: Distinguishing reflection from absorption

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Buisson, DJK 
Parker, ML 
Kara, E 
Vasudevan, RV 
Lohfink, AM 


We present two new NuSTAR observations of the narrow line Seyfert 1 (NLS1) galaxy Mrk 766 and give constraints on the two scenarios previously proposed to explain its spectrum and that of other NLS1s: relativistic reflection and partial covering. The NuSTAR spectra show a strong hard (> 15 keV) X-ray excess, while simultaneous soft X-ray coverage of one of the observations provided by XMM-Newton constrains the ionised absorption in the source. The pure reflection model requires a black hole of high spin (a > 0.92) viewed at a moderate inclination (i = 46 +1 −4 ). The pure partial covering model requires extreme parameters: the cut-off of the primary continuum is very low (22 +7 −5 keV) in one observation and the intrinsic X-ray emission must provide a large fraction (75%) of the bolometric luminosity. Allowing a hybrid model with both partial covering and reflection provides more reasonable absorption parameters and relaxes the constraints on reflection parameters. The fractional variability reduces around the iron K band and at high energies including the Compton hump, suggesting that the reflected emission is less variable than the continuum.



accretion, accretion discs, black hole physics, galaxies: individual: Mrk 766, galaxies: Seyfert

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Monthly Notices of the Royal Astronomical Society

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Oxford University Press (OUP)
Science and Technology Facilities Council (1637922)
Science and Technology Facilities Council (ST/N004027/1)
European Research Council (340442)
Science and Technology Facilities Council (ST/N000927/1)