The view of AGN-host alignment via reflection spectroscopy

Abstract

The fuelling of active galactic nuclei (AGN) -via material propagated through the galactic disc or via minor mergers -is expected to leave an imprint on the alignment of the sub-pc disc relative to the host galaxy's stellar disc. Determining the inclination of the inner disc usually relies on the launching angle of the jet; here instead we use the inclination derived from reflection fits to a sample of AGN. We determine the distorting effect of unmodeled Fe XXV/XXVI features and, via extensive simulations, determine the difference in disc inclination resulting from the use of RELXILL compared to REFLIONX. We compare inner disc inclinations to those for the host galaxy stellar disc derived from the Hubble formula and, via Monte-Carlo simulations, find a strong lack of a correlation (at ≫ 5σ) implying either widespread feeding via mergers if we assume the sample to be homogeneous, or that radiative disc warps are distorting our view of the emission. However, we find that by removing a small (∼1/5) subset of AGN, the remaining sample is consistent with random sampling of an underlying 1:1 correlation (at the 3σ level). A heterogenous sample would likely imply that our view is not dominated by radiative disc warps but instead by different feeding mechanisms with the majority consistent with coplanar accretion (although this may be the result of selection bias), whilst a smaller but not insignificant fraction may have been fuelled by minor mergers in the recent history of the host galaxy.

X-ray spectra reveal the reawakening of the repeat changing-look AGN NGC 1566

“…The inclination measured from the relativistic Fe line is very low (< 11°), which is consistent with the accretion disk being aligned with the face-on galaxy. While this is expected, we note that Middleton et al (2016) found that there is not a strong correlation between host and disk inclinations. We find only an upper limit on the spin, of < 0.25.…”

Studying the Reflection Spectra of the New Black Hole X-Ray Binary Candidate MAXI J1631−479 Observed by NuSTAR: A Variable Broad Iron Line Profile

“…The iron abundance measured by the relxilllp model is consistent with the solar value, A Fe = 1.0 +0.3 −0.1 , which is also in agreement with the value of elemental abundances fixed in the refbhb model. We note that certain systematic uncertainties could be introduced when fitting the spectra with different reflection models (e.g., see the discussion in Middleton et al 2016), but the well agreement we find in i and A Fe determined by the refbhb and relxilllp reflection models indicates such uncertainties are probably minimal here.…”

The nuclear environment of the NLS1 Mrk 335: Obscuration of the X-ray line emission by a variable outflow

“…The broad iron line measured in other observations (Parker et al 2014a;Gallo et al 2015Gallo et al , 2019) also argues against a fully face-on configuration, as this would produce a relatively narrow line (although the inner disk does not necessarily have to be aligned with the larger AGN system, e.g. Middleton et al 2016). Similarly, we cannot distinguish between rotational broadening and velocity gradi-ents within the outflow itself, so the distance estimates from the velocity should be treated with caution.…”