The ionized gas outflow in the Circinus galaxy: kinematics and physical conditions

Abstract

We employ MUSE/VLT data to study the ionised and highly ionised gas phases of the feedback in Circinus, the closest Seyfert 2 galaxy to us. The analysis of the nebular emission allowed us to detect a remarkable high-ionisation gas outflow beyond the galaxy plane traced by the coronal lines [Fe vii] λ6089 and [Fe x] λ6374, extending up to 700 pc and 350 pc NW from the nucleus, respectively. This is the first time that the [Fe x] emission is observed at such distances from the central engine in an AGN. The gas kinematics reveals expanding gas shells with velocities of a few hundred km s−1, spatially coincident with prominent hard X-ray emission detected by Chandra. Density and temperature sensitive line ratios show that the extended high-ionisation gas is characterized by a temperature reaching 25000 K and an electron density >102 cm−3 . We found that local gas excitation by shocks produced by the passage of a radio jet leads to the spectacular high-ionisation emission in this object. This hypothesis is fully supported by photoionisation models that accounts for the combined effects of the central engine and shocks. They reproduce the observed emission line spectrum at different locations inside and outside of the NW ionisation cone. The energetic outflow produced by the radio jet is spatially located close to an extended molecular outflow recently reported using ALMA which suggests that they both represent different phases of the same feedback process acting on the AGN.

The many faces of the Seyfert galaxy NGC 5643

“…We also find an unusual enhancement of Hα and Our results point to a connection between the ionization and the radio jet, as suggested in Fonseca-Faria et al (2021) and Simpson et al (1997).…”

“…Many mechanisms associated with AGN can produce coronal lines such as hot accretion disk around intermediate-mass black holes (Cann et al, 2018), reflection from the inner torus wall (Rose et al, 2015), fast shocks triggered by outflows (Fonseca-Faria et al, 2021) or even a NLR dominated by matter-bounded clouds (Cerqueira-Campos et al, 2021). The last two will be discussed in this work.…”

“…Such X-rays can photoionize the gas leading to highly ionized species (May and Steiner, 2017). Jets were found to trigger CLs in recent studies (May et al, 2018;Fonseca-Faria et al, 2021, in particular, found [Fe VII]λ6086 extended emission, up to 2 kpc, in a sample of 5 local Seyferts. The authors associated this emission with dust-free regions and also found that this emission is well-matched to X-ray and radio jet emissions.…”

CLASS Survey Description: Coronal-line Needles in the SDSS Haystack

“…Near-infrared (NIR) coronal-line studies in particular have further traced nuclear activity and ionized gas outflows in highly obscured AGNs (Rodríguez-Ardila et al 2002;Riffel et al 2006;Lamperti et al 2017;Müller-Sánchez et al 2018). Moreover, coronal-line emission can potentially be used to constrain accretion disk models (e.g., Moorwood et al 1996;Alexander et al 2000), study the properties of the dense gas in close proximity to the SMBH, and study outflows of the highly ionized gas near their launch origin (e.g., Erkens et al 1997;Rodríguez-Ardila et al 2006;Bohn et al 2021;Fonseca-Faria et al 2021), which is of crucial importance in understanding AGN feedback in the host. The coronal-line region samples gas with a wide range of densities, and it can extend several hundred parsecs from the nucleus (e.g., Müller-Sánchez et al 2011;Fonseca-Faria et al 2021), with some of the emission originating between the broad-line region and the narrow-line region, as demonstrated by recent Very Large Telescope/GRAVITY observations (Gravity Collaboration et al 2021).…”

“…Moreover, coronal-line emission can potentially be used to constrain accretion disk models (e.g., Moorwood et al 1996;Alexander et al 2000), study the properties of the dense gas in close proximity to the SMBH, and study outflows of the highly ionized gas near their launch origin (e.g., Erkens et al 1997;Rodríguez-Ardila et al 2006;Bohn et al 2021;Fonseca-Faria et al 2021), which is of crucial importance in understanding AGN feedback in the host. The coronal-line region samples gas with a wide range of densities, and it can extend several hundred parsecs from the nucleus (e.g., Müller-Sánchez et al 2011;Fonseca-Faria et al 2021), with some of the emission originating between the broad-line region and the narrow-line region, as demonstrated by recent Very Large Telescope/GRAVITY observations (Gravity Collaboration et al 2021). Because the spectral energy distribution of the accretion disk hardens with decreasing black hole mass, coronal-line ratios may even have the potential to constrain the black hole mass and reveal accreting intermediate mass black holes (e.g., Cann et al 2018;Molina et al 2021aMolina et al , 2021bCann et al 2021).…”