The multiphase gas structure and kinematics in the circumnuclear region of NGC 5728

Abstract

We report on our combined analysis of HST, VLT/MUSE, VLT/SINFONI, and ALMA observations of the local Seyfert 2 galaxy, NGC 5728 to investigate in detail the feeding and feedback of the AGN. The datasets simultaneously probe the morphology, excitation, and kinematics of the stars, ionized gas, and molecular gas over a large range of spatial scales (10 pc-10 kpc). NGC 5728 contains a large stellar bar which is driving gas along prominent dust lanes to the inner 1 kpc where the gas settles into a circumnuclear ring. The ring is strongly star forming and contains a substantial population of young stars as indicated by the lowered stellar velocity dispersion and gas excitation consistent with HII regions. We model the kinematics of the ring using the velocity field of the CO (2-1) emission and stars and find it is consistent with a rotating disk. The outer regions of the disk, where the dust lanes meet the ring, show signatures of inflow at a rate of 1 M yr −1 . Inside the ring, we observe three molecular gas components corresponding to the circular rotation of the outer ring, a warped disk, and the nuclear stellar bar. The AGN is driving an ionized gas outflow that reaches a radius of 250 pc with a mass outflow rate of 0.08 M yr −1 consistent with its luminosity and scaling relations from previous studies. While we observe distinct holes in CO emission which could be signs of molecular gas removal, we find that largely the AGN is not disrupting the structure of the circumnuclear region.

Ionized outflows in local luminous AGN: what are the real densities and outflow rates?

“…This tendency is also reflected in spatially resolved studies (e.g. Baron et al 2018;Freitas et al 2018;Kakkad et al 2018;do Nascimento et al 2019;Hinkle, Veilleux & Rupke 2019;Shimizu et al 2019) that tend to show that n e decreases with radius.…”

“…They demonstrate that even the narrower profiles among our AGN are consistent with an outflow origin. Shimizu et al (2019) compared several methods of measuring the electron density using both high and moderate resolution data. They showed that for data with R < 4000, blending of the [S II] line profiles in this object leads to an increasing discrepancy in the derived density at smaller radii -with an order of magnitude underestimation at radial scales below 500 pc.…”

“…To avoid the limitations of the [S II] doublet ratio, Holt et al (2011) proposed an alternative method that has now been applied to a variety of different types of objects, and been shown to be sensitive to higher densities (Holt et al 2011;Rose et al 2018;Santoro et al 2018;Shimizu et al 2019). We will refer to this as the TA method because it uses the transauroral lines [S II] λλ4069, 4076 and the auroral lines [O II] λλ7320, 7331 (each of the lines within this 11 Å separation doublet is itself a doublet, but their separations of ∼1 Å are sufficiently small that at the spectral resolution here they can be considered single lines), which have higher critical densities.…”

“…In the literature, a wide range of different densities (either assumed or measured), covering several orders of magnitude, have been used when deriving quantities related to ionized outflows driven by AGN. These include, at low and high redshift: 100 cm −3 (Liu et al 2013;Riffel, Storchi-Bergmann & Winge 2013;Harrison et al 2014;Kakkad et al 2016;Rupke, Gültekin & Veilleux 2017); 200 cm −3 (Fiore et al 2017); 500 cm −3 (Storchi-Bergmann et al 2010;Carniani et al 2015;Riffel, Storchi-Bergmann & Riffel 2015); 1000-1500 cm −3 (Schnorr-Müller et al 2016a;Perna et al 2017;Förster Schreiber et al 2019;Shimizu et al 2019); 5000 cm −3 (Müller-Sánchez et al 2011); and in some instances densities of 10 4 -10 5 cm −3 have been reported (Holt et al 2011;Rose et al 2018;Santoro et al 2018;Baron & Netzer 2019). Among this plethora of values, lower densities are often adopted or measured for larger scales of 1-10 kpc, while the higher densities apply to smaller 0.1-1 kpc scales.…”

A binning-free method reveals a continuous relationship between galaxies’ AGN power and offset from main sequence

“…E-mail: lpgrimmett1@sheffield.ac.uk Recent observations of the inner few (tens of) parsecs of galaxies hosting AGNs have revealed evidence of bars and spiral structures that may be funnelling material toward the central SMBH (e.g. Shlosman, Frank & Begelman 1989;Storchi-Bergmann et al 2007;Audibert et al 2019;Shimizu et al 2019). While such studies are important for revealing how gas and dust are transferred from the host galaxy, they do not address the question of what 'macroscopic' galaxy properties help to trigger BH growth.…”