Open AccessX‐rays from the radio‐quiet quasar PG 1407+265: relativistic jet or accretion disc emission?
Author(s) -
Gallo L. C.
Publication year - 2006
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.1365-2966.2005.09780.x
Subject(s) - physics , astrophysics , quasar , flux (metallurgy) , astrophysical jet , emission spectrum , active galactic nucleus , light curve , astronomy , spectral energy distribution , spectral line , ionization , accretion disc , spectral index , accretion (finance) , jet (fluid) , galaxy , ion , materials science , quantum mechanics , metallurgy , thermodynamics
We present two XMM–Newton observations of the luminous ( L x > 10 46 erg s −1 ) , radio‐quiet quasar PG 1407+265, separated by 11 months. The data indicate two distinct states: a highly variable, bright state (first epoch); and a quiescent, low‐flux one (second epoch). During the low‐flux state the spectrum is consistent with a single, unabsorbed power law. However, during the brighter state a highly variable, steep component is statistically required. Contemporaneous ultraviolet data from the Optical Monitor allow an estimate of the optical‐to‐X‐ray spectral index (α ox ) , which appears typical of radio‐quiet quasars during the low‐flux state, but extremely flat during the high‐flux state. The XMM–Newton data can be described as originating from a combination of jet and accretion disc processes, in which the (relativistic) X‐ray jet only works intermittently. The scenario could help to describe some of the complexities seen in the broad‐band spectral energy distribution of PG 1407+265, such as weak high‐ionization emission lines, strong Fe ii , unbeamed continuum and the weak radio emission relative to the optical.