A Momentum-conserving Accretion Disk Wind in the Narrow-line Seyfert 1 I Zwicky 1

Abstract

Abstract I Zwicky 1 (hereafter I Zw 1) is the prototype optical narrow-line Seyfert 1 galaxy. It is also a nearby (z = 0.0611), luminous quasi-stellar object (QSO), accreting close to the Eddington limit. XMM-Newton observations of I Zw 1 in 2015 reveal the presence of a broad and blueshifted P Cygni iron K profile, as observed through a blueshifted absorption trough at 9 keV and a broad excess of emission at 7 keV in the X-ray spectra. The profile can be well fitted with a wide-angle accretion disk wind, with an outflow velocity of at least −0.25c. In this respect, I Zw 1 may be analogous to the prototype fast wind detected in the QSO PDS 456, while its overall mass outflow rate is scaled down by a factor of 50, due to its lower black hole mass. The mechanical power of the fast wind in I Zw 1 is constrained to within 5%–15% of Eddington, while its momentum rate is of the order unity. Upper limits placed on the energetics of any molecular outflow, from its CO profile measured by IRAM, appear to rule out the presence of a powerful, large-scale, energy-conserving wind in this active galactic nucleus (AGN). We consider whether I Zw 1 may be similar to a number of other AGNs, such as PDS 456, where the large-scale galactic outflow is much weaker than what is anticipated from models of energy-conserving feedback.