115 research outputs found
AGN outflows and feedback twenty years on
It is the twentieth anniversary of the publication of the seminal papers by
Magorrian et al. and Silk & Rees which, along with other related work, ignited
an explosion of publications connecting active galactic nuclei (AGN)-driven
outflows to galaxy evolution. With a surge in observations of AGN outflows,
studies are attempting to directly test AGN feedback models using the outflow
properties. With a focus on outflows traced by optical and CO emission lines,
we discuss significant challenges which greatly complicate this task from both
an observational and theoretical perspective. We highlight observational
uncertainties involved, and the assumptions required, when deriving kinetic
coupling efficiencies (i.e., outflow kinetic power as a fraction of AGN
luminosity) from typical observations. Based on recent models we demonstrate
that extreme caution should taken when comparing observationally-derived
kinetic coupling efficiencies to coupling efficiencies from fiducial feedback
models.Comment: Authors' version (all referee comments addressed). 7 pages +
references. Published in Nature Astronom
BAT AGN spectroscopic survey, XIX : type 1 versus type 2 AGN dichotomy from the point of view of ionized outflows
We present a detailed study of ionized outflows in a large sample of similar to 650 hard X-ray-detected active galactic neuclei (AGNs). Using optical spectroscopy from the BAT AGN Spectroscopic Survey (BASS), we are able to reveal the faint wings of the [OIII] emission lines associated with outflows covering, for the first time, an unexplored range of low AGN bolometric luminosity at low redshift (z similar to 0.05). We test if and how the incidence and velocity of ionized outflow is related to AGN physical parameters: black hole mass (M-BH), gas column density (N-H), Eddington ratio (lambda(Edd)), [OIII], X-ray, and bolometric luminosities. We find a higher occurrence of ionized outflows in type 1.9 (55 per cent) and type 1 AGNs (46 per cent) with respect to type 2 AGNs (24 per cent). While outflows in type 2 AGNs are evenly balanced between blue and red velocity offsets with respect to the [OIII] narrow component, they are almost exclusively blueshifted in type 1 and type 1.9 AGNs. We observe a significant dependence between the outflow occurrence and accretion rate, which becomes relevant at high Eddington ratios [log(lambda(Edd)) greater than or similar to -1.7]. We interpret such behaviour in the framework of covering factor-Eddington ratio dependence. We do not find strong trends of the outflow maximum velocity with AGN physical parameters, as an increase with bolometric luminosity can be only identified when including samples of AGNs at high luminosity and high redshift taken from literature
The quasar feedback survey: discovering hidden Radio-AGN and their connection to the host galaxy ionized gas
We present the first results from the Quasar Feedback Survey, a sample of 42 z 1042.1 ergs s−1) with moderate radio luminosities (i.e. L1.4GHz > 1023.4 W Hz−1; median L1.4GHz = 5.9 × 1023 W Hz−1). Using high spatial resolution (∼0.3–1 arcsec), 1.5–6 GHz radio images from the Very Large Array, we find that 67 per cent of the sample have spatially extended radio features on ∼1–60 kpc scales. The radio sizes and morphologies suggest that these may be lower radio luminosity versions of compact, radio-loud AGNs. By combining the radio-to-infrared excess parameter, spectral index, radio morphology, and brightness temperature, we find radio emission in at least 57 per cent of the sample that is associated with AGN-related processes (e.g. jets, quasar-driven winds, or coronal emission). This is despite only 9.5–21 per cent being classified as radio-loud using traditional criteria. The origin of the radio emission in the remainder of the sample is unclear. We find that both the established anticorrelation between radio size and the width of the [O III] line, and the known trend for the most [O III] luminous AGNs to be associated with spatially extended radio emission, also hold for our sample of moderate radio luminosity quasars. These observations add to the growing evidence of a connection between the radio emission and ionized gas in quasar host galaxies. This work lays the foundation for deeper investigations into the drivers and impact of feedback in this unique sample
BAT AGN Spectroscopic Survey – XIX. Type 1 versus type 2 AGN dichotomy from the point of view of ionized outflows
We present a detailed study of ionized outflows in a large sample of ∼650 hard X-ray-detected active galactic neuclei (AGNs). Using optical spectroscopy from the BAT AGN Spectroscopic Survey (BASS), we are able to reveal the faint wings of the [O III] emission lines associated with outflows covering, for the first time, an unexplored range of low AGN bolometric luminosity at low redshift (z ∼0.05). We test if and how the incidence and velocity of ionized outflow is related to AGN physical parameters: black hole mass (M_(BH)), gas column density (N_H), Eddington ratio (λ_(Edd)), [O III], X-ray, and bolometric luminosities. We find a higher occurrence of ionized outflows in type 1.9 (55 per cent) and type 1 AGNs (46 per cent) with respect to type 2 AGNs (24 per cent). While outflows in type 2 AGNs are evenly balanced between blue and red velocity offsets with respect to the [O III] narrow component, they are almost exclusively blueshifted in type 1 and type 1.9 AGNs. We observe a significant dependence between the outflow occurrence and accretion rate, which becomes relevant at high Eddington ratios [log(λ_(Edd)) ≳ −1.7]. We interpret such behaviour in the framework of covering factor-Eddington ratio dependence. We do not find strong trends of the outflow maximum velocity with AGN physical parameters, as an increase with bolometric luminosity can be only identified when including samples of AGNs at high luminosity and high redshift taken from literature
BAT AGN Spectroscopic Survey - XIX. Type 1 versus type 2 AGN dichotomy from the point of view of ionized outflows
We present a detailed study of ionized outflows in a large sample of ∼650 hard X-ray-detected active galactic neuclei (AGNs). Using optical spectroscopy from the BAT AGN Spectroscopic Survey (BASS), we are able to reveal the faint wings of the [O iii] emission lines associated with outflows covering, for the first time, an unexplored range of low AGN bolometric luminosity at low redshift (z ∼0.05). We test if and how the incidence and velocity of ionized outflow is related to AGN physical parameters: black hole mass, gas column density, Eddington ratio, [O iii], X-ray, and bolometric luminosities. We find a higher occurrence of ionized outflows in type 1.9 (55 per cent) and type 1 AGNs (46 per cent) with respect to type 2 AGNs (24 per cent). While outflows in type 2 AGNs are evenly balanced between blue and red velocity offsets with respect to the [O iii] narrow component, they are almost exclusively blueshifted in type 1 and type 1.9 AGNs. We observe a significant dependence between the outflow occurrence and accretion rate, which becomes relevant at high Eddington ratios. We interpret such behaviour in the framework of covering factor-Eddington ratio dependence. We do not find strong trends of the outflow maximum velocity with AGN physical parameters, as an increase with bolometric luminosity can be only identified when including samples of AGNs at high luminosity and high redshift taken from literature
The Quasar Feedback Survey: characterising CO excitation in quasar host galaxies
We present a comprehensive study of the molecular gas properties of 17 Type 2
quasars at 10^{42.1}\rm ergs^{-1}_{up}r_{21}_{21}_{CO(2-1)}_{CO(1-0)}r_{21}r_{21}\sim_{21}\simr_{21} values, for the 7
targets with the required data we find low excitation in CO(6-5) & CO(7-6)
(r_{61}r_{62}$ < 0.6 in all but one target), unlike high redshift
quasars in the literature, which are far more luminous and show higher line
ratios. The ionised gas traced by [OIII] exhibit systematically higher
velocities than the molecular gas traced by CO. We conclude that any effects of
quasar feedback (e.g. via outflows and radio jets) do not have a significant
instantaneous impact on the global molecular gas content and excitation and we
suggest that it only occurs on more localised scales.Comment: 32 pages (20 in the main body of the paper and 12 in the appendix),
28 figures (10 in main body of paper and 18 in appendix) Accepted for
publication in MNRAS. Data available at
https://doi.org/10.25405/data.ncl.2431250
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