High-density disc reflection spectroscopy of low-mass active galactic nuclei

ABSTRACT The standard alpha-disc model predicts an anticorrelation between the density of inner accretion disc and black hole mass times square rate, as seen in higher (MBH > 106 M⊙) active galactic nuclei (AGNs). In this work, we test predictions study properties flow for low-mass end ≈ 105–6 AGNs. We utilize a new high-density reflection where parameter varies from ne = 1015 to 1020 cm−3 apply it broad-band X-ray (0.3–10 keV) spectra AGN sample. sources span wide range Eddington fractions are consistent with being sub-Eddington or near-Eddington. reveal soft excess below ∼1.5 keV which is well modelled by ionized ∼ 1018 on average. results suggest radiation pressure-dominated average 70 per cent fraction power transferred corona, that observed show than can result pressure compression when surface does not hold strong magnetic gradient. find tentative evidence drop spin at regimes.