NuSTAR observations of Mrk 766: distinguishing reflection from absorption. Issue 3 (1st August 2018)

• Record Type: Journal Article
• Authors: Buisson, D J K; Parker, M L; Kara, E; Vasudevan, R V; Lohfink, A M; Pinto, C; Fabian, A C; Ballantyne, D R; Boggs, S E; Christensen, F E; Craig, W W; Farrah, D; Hailey, C J; Harrison, F A; Ricci, C; Stern, D; Walton, D J; Zhang, W W
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 480:Issue 3(2018)
• Page Start: 3689
• Page End: 3701
• Publication Date: 2018-08-01
• Subjects: accretion, accretion discs -- black hole physics -- galaxies: individual: Mrk 766 -- galaxies: Seyfert; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty2081
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: 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 ionized absorption in the source. The pure reflection model requires a black hole of high spin ( a > 0.92) viewed at a moderate inclination ($i=46_{-4}^{+1}\, ^\circ$ ). The pure partial covering model requires extreme parameters: the cut-off of the primary continuum is very low ($22_{-5}^{+7}$ keV) in one observation and the intrinsic X-ray emission must provide a large fraction (75 per cent) 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.