MAGNUM survey: A MUSE-Chandra resolved view on ionized outflows and photoionization in the Seyfert galaxy NGC1365

Abstract

Context. Ionized outflows, revealed by broad asymmetric wings of the [O iii] λ5007 line, are commonly observed in active galactic nuclei (AGN) but the low intrinsic spatial resolution of the observations has generally prevented a detailed characterization of their properties. The MAGNUM survey aims at overcoming these limitations by focusing on the nearest AGN, including NGC 1365, a nearby Seyfert galaxy (D ∼ 17 Mpc), hosting a low-luminosity active nucleus (L bol ∼ 2 × 10 43 erg s −1 ). Aims. We want to obtain a detailed picture of the ionized gas in the central ∼5 kpc of NGC 1365 in terms of physical properties, kinematics, and ionization mechanisms. We also aim to characterize the warm ionized outflow as a function of distance from the nucleus and its relation with the nuclear X-ray wind. Methods. We employed optical integral-field spectroscopic observations from VLT/MUSE to investigate the warm ionized gas and Chandra ACIS-S X-ray data for the hot highly-ionized phase. We obtained flux, kinematic, and diagnostic maps of the optical emission lines, which we used to disentangle outflows from gravitational motions in the disk and measure the gas properties down to a spatial resolution of ∼70 pc. We then performed imaging spectroscopy on Chandra ACIS-S data guided by the matching with MUSE maps. Results. The [O iii] emission mostly traces a kpc-scale biconical outflow ionized by the AGN having velocities up to ∼200 km s −1 . Hα emission traces instead star formation in a circumnuclear ring and along the bar, where we detect non-circular streaming gas motions. Soft X-rays are predominantly due to thermal emission from the star-forming regions, but we manage to isolate the AGN photoionized component which nicely matches the [O iii] emission. The mass outflow rate of the extended ionized outflow is similar to that of the nuclear X-ray wind and then decreases with radius, implying that the outflow either slows down or that the AGN activity has recently increased. However, the hard X-ray emission from the circumnuclear ring suggests that star formation might in principle contribute to the outflow. The integrated mass outflow rate, kinetic energy rate, and outflow velocity are broadly consistent with the typical relations observed in more luminous AGN.

The MAGNUM survey: different gas properties in the outflowing and disc components in nearby active galaxies with MUSE

“…A comprehensive review about the early works on this object is given by Lindblad (1999). Our MUSE data was already published by Venturi et al (2018), who studied the circumnuclear gas in its different phases by comparing MUSE and Chandra data and analysing the nuclear and extended gas outflows. Specifically, Venturi et al (2018) revealed that [O iii] emission that traces the kpc-scale biconical outflow, ionised by the AGN, is nicely matched with the soft X-rays.…”

“…Our MUSE data was already published by Venturi et al (2018), who studied the circumnuclear gas in its different phases by comparing MUSE and Chandra data and analysing the nuclear and extended gas outflows. Specifically, Venturi et al (2018) revealed that [O iii] emission that traces the kpc-scale biconical outflow, ionised by the AGN, is nicely matched with the soft X-rays. However, the hard X-ray emission from the starforming circumnuclear ring suggests that SF might in principle contribute to the outflow.…”

KASHz: No evidence for ionised outflows instantaneously suppressing star formation in moderate luminosity AGN at z ∼ 1.4–2.6

“…Based on (1) the discrepancy between star-formation rates inferred from Hα compared to those from FIR; (2) the different sizes and distributions of the FIR (tracing obscured star formation) compared to the Hα distribution and; (3) the challenges in decoupling the contribution of star-formation from the AGN contribution to producing the Hα emission, we conclude that Hα emission alone is not a reliable tracer of the star-formation in the AGN host galaxies in our sample. These challenges can be overcome, at least to some degree, in IFU observations of local AGN since the high spatial resolution observations can result in maps of multiple emissionline ratio diagnostics (e.g., Venturi et al 2018;D'Agostino et al 2019). However, with the current observational facilities this is rarely possible for high-z systems and caution, and a careful case-by-case assessment is required when using Hα emission to trace star-formation in high-z AGN host galaxies.…”

“…Measurements are more accurate for the most nearby sources (e.g. Revalski et al 2018;Venturi et al 2018;Fluetsch et al 2019); however, these samples lack the most powerful AGN which are thought to be the most important for influencing galaxy evolution.…”

GASP – XIX. AGN and their outflows at the centre of jellyfish galaxies

“…A major improvement in our understanding of the complex environment around AGN is given by the availability of Integral Field Spectroscopy (IFU), allowing to map emission line fluxes and kinematics tracing the AGN and its surroundings (see e.g. Venturi et al 2018;Ilha et al 2019;Mingozzi et al 2019).…”