Nuclear molecular outflow in the Seyfert galaxy NGC 3227

Abstract

ALMA observations have revealed nuclear dusty molecular disks/tori with characteristic sizes 15-40 pc in the few Seyferts and low luminosity AGN studied so far. These structures are generally decoupled both morphologically and kinematically from the host galaxy disk. We present ALMA observations of the CO(2-1) and CO(3-2) molecular gas transitions and associated (sub)-millimeter continua of the nearby Seyfert 1.5 galaxy NGC 3227 with angular resolutions 0.085 − 0.21 (7-15 pc). On large scales the cold molecular gas shows circular motions as well as streaming motions on scales of a few hundred parsecs associated with a large scale bar. We fitted the nuclear ALMA 1.3 mm emission with an unresolved component and an extended component. The 850 µm emission shows at least two extended components, one along the major axis of the nuclear disk and the other along the axis of the ionization cone. The molecular gas in the central region (1 ∼ 73 pc) shows several CO clumps with complex kinematics which appears to be dominated by non-circular motions. While we cannot demonstrate conclusively the presence of a warped nuclear disk, we also detected non-circular motions along the kinematic minor axis. They reach line-of-sight velocities of v − v sys = 150 − 200 km s −1 . Assuming that the radial motions are in the plane of the galaxy, then we interpret them as a nuclear molecular outflow due to molecular gas in the host galaxy being entrained by the AGN wind. We derive molecular outflow rates of 5 M yr −1 and 0.6 M yr −1 at projected distances of up to 30 pc to the northeast and southwest of the AGN, respectively. At the AGN location we estimate a mass in molecular gas of 5 × 10 5 M and an equivalent average column density N(H 2 ) = 2 − 3 × 10 23 cm −2 in the inner 15 pc. The nuclear CO(2-1) and CO(3-2) molecular gas and sub-mm continuum emission of NGC 3227 do not resemble the classical compact torus. Rather, these emissions extend for several tens of parsecs and appear connected with the circumnuclear ring in the host galaxy disk, as found in other local AGN.

Cold molecular gas and PAH emission in the nuclear and circumnuclear regions of Seyfert galaxies

“…Six galaxies have only one peak in the field of view, and the peak coordinates agree well with the radio peaks listed in the literature as follows: IC 4518W in Condon et al (1996), NGC 1386 and NGC 7172 in Thean et al (2000), and NGC 7213 in Bransford et al (1998). NGC 3227 and NGC 5643 are discussed in detail in Alonso-Herrero et al (2019) and Alonso-Herrero et al (2018), respectively. The remaining seven show several peaks in the ALMA 1.3 mm continuum maps and are discussed below.…”

“…A number of works have shown that the continuum emission at 1.3 mm in Seyfert galaxies is mostly produced by synchrotron emission with varying contributions from cold dust emission and free-free emission (Pasetto et al 2019;Alonso-Herrero et al 2019;García-Burillo et al 2019). We therefore assumed that the peak of the 1.3 mm can be used to locate the position of the AGN (see also Appendix A).…”

Radiation Hydrodynamics Models of Active Galactic Nuclei: Beyond the Central Parsec

“…We can qualitatively compare our p-v maps with those of NGC 1068 (García-Burillo et al 2019;Impellizzeri et al 2019), NGC 3227 (Alonso-Herrero et al 2019), and Circinus (Izumi et al 2018). Our model parameters are closest to those of Circinus (although at a lower γ edd ), and a similar basic structure is seen -a central 'blob', and a sharp peak of red and blue shift in the center.…”

“…High resolution ALMA observations show the molecular components of AGNs have signs of inflows, outflows, rotation, a possibly lopsided or misaligned morphology, and non-circular motions or perhaps even counterrotation (García-Burillo et al 2016;Alonso-Herrero et al 2018;Izumi et al 2018;Alonso-Herrero et al 2019;Impellizzeri et al 2019;García-Burillo et al 2019;Tang et al 2019). Infrared interferometry additionally reveals an extended polar structure, suggesting a biconical dusty wind emitted from the 'torus' region (Hönig et al 2012(Hönig et al , 2013Tristram et al 2014;López-Gonzaga et al 2016;Leftley et al 2018).…”

Active galactic nuclei winds as the origin of the H2 emission excess in nearby galaxies

“…Fischer et al 2010;Veilleux et al 2013;González-Alfonso et al 2014 and spatially resolved with Atacama Large Millimeter Array (ALMA) observations of CO lines (e.g. Combes et al 2013;García-Burillo et al 2014;Morganti et al 2015;Pereira-Santaella et al 2018;Ramakrishnan et al 2019;Alonso-Herrero et al 2019;Husemann et al 2019). These studies reveal outflows with velocities ranging from few tens of km s −1 to over 1 000 km s −1 , mass-outflow rates of up to 10 3 M yr −1 and kinetic power as high as 10 44 erg s −1 .…”