Open AccessA transition in the accretion properties of radio‐loud active nuclei
Author(s) -
Marchesini Danilo,
Celotti Annalisa,
Ferrarese Laura
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.07822.x
Subject(s) - physics , astrophysics , accretion (finance) , quasar , radiative transfer , active galactic nucleus , astronomy , radio galaxy , galaxy , quantum mechanics
ABSTRACT We present evidence for the presence of a transition in the accretion properties of radio‐loud sources. For a sample of radio galaxies and radio‐loud quasars, selected based on their extended radio properties, the accretion rate is estimated from the black hole mass and nuclear luminosity. The inferred distribution is bimodal, with a paucity of sources at accretion rates, in Eddington units, of the order of ∼10 −2 – assuming a radiative efficiency of 10 per cent – and possibly spanning 1–2 orders of magnitude. Selection biases are unlikely to be responsible for such behaviour. We discuss possible physical explanations, including a fast transition to low accretion rates, a change in the accretion mode/actual accretion rate/radiative efficiency, the lack of stable disc solutions at intermediate accretion rates or the inefficiency of the jet formation processes in geometrically thin flows. This transition might be analogous to spectral states (and jet) transitions in black hole binary systems.