Probing black hole accretion tracks, scaling relations, and radiative efficiencies from stacked X-ray active galactic nuclei

Abstract

The masses of supermassive black holes at the centres of local galaxies appear to be tightly correlated with the mass and velocity dispersions of their galactic hosts. However, the local M bh -M star relation inferred from dynamically measured inactive black holes is up to an order-of-magnitude higher than some estimates from active black holes, and recent work suggests that this discrepancy arises from selection bias on the sample of dynamical black hole mass measurements. In this work we combine X-ray measurements of the mean black hole accretion luminosity as a function of stellar mass and redshift with empirical models of galaxy stellar mass growth, integrating over time to predict the evolving M bh -M star relation. The implied relation is nearly independent of redshift, indicating that stellar and black hole masses grow, on average, at similar rates. Matching the de-biased local M bh -M star relation requires a mean radiative efficiency ε 0.15, in line with theoretical expectations for accretion onto spinning black holes. However, matching the "raw" observed relation for inactive black holes requires ε ∼ 0.02, far below theoretical expectations. This result provides independent evidence for selection bias in dynamically estimated black hole masses, a conclusion that is robust to uncertainties in bolometric corrections, obscured active black hole fractions, and kinetic accretion efficiency. For our fiducial assumptions, they favour moderate-to-rapid spins of typical supermassive black holes, to achieve ε ∼ 0.12 − 0.20. Our approach has similarities to the classic Soltan analysis, but by using galaxy-based data instead of integrated quantities we are able to focus on regimes where observational uncertainties are minimized.

Placing LOFAR-detected quasars in C iv emission space: implications for winds, jets and star formation

“…General theoretical arguments for this are given by, for example, Richards et al (2011) and Blandford et al (2019). The idea is also supported observationally by the fact that many radio-quiet AGN seem to be spinning rapidly, as inferred from X-ray observations (Reynolds 2014) and studies based on the Soltan (1982) argument (Elvis, Risaliti & Zamorani 2002;Yu & Tremaine 2002;Shankar et al 2020; see also Broderick & Fender 2011). As well as spin, the jet power also depends on the magnetic flux threading the event horizon (Blandford & Znajek 1977;Tchekhovskoy, Narayan & McKinney 2011;Davis & Tchekhovskoy 2020), which can either be generated in situ (e.g.…”

Active galactic nuclei as seen by the Spitzer Space Telescope

“…Using the Xray AGN luminosity density alone, values of ~0.15, significantly larger than the 0.05 value predicted from a Schwarzschild black hole, indicating spinning Kerr black holes (which have closer innermost stable orbits, and hence higher radiative efficiencies), are found. 105 The discovery of an even higher AGN luminosity density than inferred from the X-ray using mid-infrared selected AGN confirms that most black holes are spinning, and leaves little room for black hole growth through non-radiative or radiatively inefficient processes. 84…”

Placing LOFAR-detected quasars in CIV emission space: implications for winds, jets and star formation

“…General theoretical arguments for this are given by, for example, Richards et al (2011) and Blandford et al (2019). The idea is also supported observationally by the fact that many radio-quiet AGN seem to be spinning rapidly, as inferred from Xray observations (Reynolds 2014) and studies based on the Soltan (1982) argument (Elvis et al 2002;Yu & Tremaine 2002;Shankar et al 2020; see also Broderick & Fender 2011). As well as spin, the jet power also depends on the magnetic flux threading the event horizon (Blandford & Znajek 1977;Tchekhovskoy et al 2011;Davis & Tchekhovskoy 2020), which can either be generated in situ (e.g.…”