We present CO(2−1) and adjacent continuum observations of seven nearby radio-quiet type-2 quasars (QSO2s) obtained with ALMA at ∼0.2″ resolution (370 pc at
z
∼ 0.1). These QSO2s are luminous (
L
...OIII
> 10
8.5
L
⊙
∼
M
B
< −23), and their host galaxies massive (
M
*
∼ 10
11
M
⊙
). The CO morphologies are diverse, including disks and interacting systems. Two of the QSO2s are red early-type galaxies with no CO(2–1) detected. In the interacting galaxies, the central kiloparsec contains 18–25% of the total cold molecular gas, whereas in the spirals it is only ∼5–12%. J1010+0612 and J1430+1339 show double-peaked CO flux maps along the major axis of the CO disks that do not have an optical counterpart at the same angular resolution. Based on our analysis of the ionized and molecular gas kinematics and millimeter continuum emission, these CO morphologies are most likely produced by active galactic nucleus (AGN) feedback in the form of outflows, jets, and/or shocks. The CO kinematics of the QSO2s with CO(2−1) detections are dominated by rotation but also reveal noncircular motions. According to our analysis, these noncircular motions correspond to molecular outflows that are mostly coplanar with the CO disks in four of the QSO2s, and either to a coplanar inflow or vertical outflow in the case of J1010+0612. These outflows represent 0.2–0.7% of the QSO2s’ total molecular gas mass and have maximum velocities of 200–350 km s
−1
, radii from 0.4 to 1.3 kpc, and outflow mass rates of 8–16
M
⊙
yr
−1
. These outflow properties are intermediate between those of the mild molecular outflows measured for Seyfert galaxies and the fast and energetic outflows shown by ultra-luminous infrared galaxies. This suggests that it is not only AGN luminosity that drives massive molecular outflows. Other factors such as jet power, coupling between winds, jets, and/or ionized outflows and the CO disks, and amount or geometry of dense gas in the nuclear regions might also be relevant. Thus, although we do not find evidence for a significant impact of quasar feedback on the total molecular gas reservoirs and star formation rates, it appears to be modifying the distribution of cold molecular gas in the central kiloparsec of the galaxies.
We present intermediate-resolution, wide-wavelength coverage spectra for a complete sample of 14 compact radio sources taken with the aim of investigating the impact of the nuclear activity on the ...circumnuclear interstellar medium (ISM) in the early stages of radio source evolution. We observe spatially extended line emission (up to ∼20 kpc) in the majority of sources which is consistent with a quiescent halo. In the nuclear apertures we observe broad, highly complex emission-line profiles. Multiple Gaussian modelling of the O iiiλ5007 line reveals between two and four components which can have velocity widths full width at half-maximum (FWHM) and blueshifts relative to the halo of up to ∼2000 km s−1. We interpret these broad, blueshifted components as material in outflow and discuss the kinematical evidence for jet-driven outflows as previously proposed for PKS 1549−79 and PKS 1345+12. Comparisons with samples in the literature show that compact radio sources harbour more extreme nuclear kinematics than their extended counterparts, a trend seen within our sample with larger velocities in the smaller sources. The observed velocities are also likely to be influenced by source orientation with respect to the observer's line of sight. Nine sources have associated H i absorption. In common with the optical emission-line gas, the H i profiles are often highly complex with the majority of the detected components significantly blueshifted, tracing outflows in the neutral gas. The sample has been tested for stratification in the ISM (FWHM/ionization potential/critical density) as suggested by Holt, Tadhunter & Morganti for PKS 1345+12 but we find no significant trends within the sample using a Spearman rank analysis. This study supports the idea that compact radio sources are young radio-loud active galactic nuclei observed during the early stages of their evolution and currently shedding their natal cocoons through extreme circumnuclear outflows.
ABSTRACT
Based on new near-infrared spectroscopic data from the instrument Espectrógrafo Multiobjeto Infra-Rojo (EMIR) on the 10.4 m Gran Telescopio Canarias, we report the presence of an ionized and ...warm molecular outflow in the luminous type-2 quasar J150904.22+043441.8 (z = 0.1118). The ionized outflow is faster than its molecular counterpart, although the outflow sizes that we derive for them are consistent within the errors (1.34 ± 0.18 and 1.46 ± 0.20 kpc, respectively). We use these radii, the broad emission-line luminosities and in the case of the ionized outflow, the density calculated from the trans-auroral O ii and S ii lines, to derive mass outflow rates and kinetic coupling efficiencies. While the ionized and warm molecular outflows represent a small fraction of the AGN power (≤0.033 and 0.0001 per cent of Lbol, respectively), the total molecular outflow, whose mass is estimated from an assumed warm-to-cold gas mass ratio of 6 × 10−5, has a kinetic coupling efficiency of ∼1.7 per cent Lbol. Despite the large uncertainty, this molecular outflow represents a significant fraction ofLbol and it could potentially have a significant impact on the host galaxy. In addition, the quasar spectrum reveals bright and patchy narrow Paα emission extending out to 4 arcsec (8 kpc) south-east and north-west from the active nucleus.
We present an optical spectroscopic study of a 90 per cent complete sample of nearby ULIRGs (z < 0.175) with optical Seyfert nuclei, with the aim of investigating the nature of the near-nuclear (r ...3.5 kpc) warm gas outflows. A high proportion (94 per cent) of our sample show disturbed emission line kinematics in the form of broad (FWHM > 500 km s−1) and/or strongly blueshifted (ΔV < −150 km s−1) emission line components. This proportion is significantly higher than found in a comparison sample of nearby ultraluminous infrared galaxies (ULIRGs) that lack optical Seyfert nuclei (19 per cent). We also find evidence that the emission line kinematics of the Sy-ULIRGs are more highly disturbed than those of samples of non-ULIRG Seyferts and Palomar-Green quasars in the sense that, on average, their O iii λλ5007, 4959 emission lines are broader and more asymmetric.
The Sy-ULIRG sample encompasses a wide diversity of emission line profiles. In most individual objects, we are able to fit the profiles of all the emission lines of different ionization with a kinematic model derived from the strong O iii λλ4959, 5007 lines, using between two and five Gaussian components. From these fits, we derive diagnostic line ratios that are used to investigate the ionization mechanisms for the different kinematic components. We show that, in general, the line ratios are consistent with gas of supersolar abundance photoionized by a combination of AGN and starburst activity, with an increasing contribution from the AGN with increasing FWHM of the individual kinematic components, and the AGN contribution dominating for the broadest components. However, shock ionization cannot be ruled out in some cases. Our derived upper limits on the mass outflows rates and kinetic powers of the emission line outflows show that they can be as energetically significant as the neutral and molecular outflows in ULIRGs - consistent with the requirements of the hydrodynamic simulations that include AGN feedback. However, the uncertainties are large, and more accurate estimates of the radii, densities and reddening of the outflows are required to put these results on a firmer footing.
We present new deep Very Large Telescope (VLT)/FORS optical spectra with intermediate resolution and large wavelength coverage of the compact radio source and ultra-luminous IR galaxy (ULIRG) PKS ...1345+12 (4C 12.50; z= 0.122), taken with the aim of investigating the impact of the nuclear activity on the circumnuclear interstellar medium (ISM). PKS 1345+12 is a powerful quasar L(Hβ)NLR∼ 1042 erg s−1 and is also the best studied case of an emission line outflow in a ULIRG. Using the density-sensitive transauroral emission lines S ii4068,4076 and O ii7318,7319,7330,7331, we pilot a new technique to accurately model the electron density for cases in which it is not possible to use the traditional diagnostic S ii6716/6731, namely sources with highly broadened complex emission line profiles and/or high (N
e≳ 104 cm−3) electron densities. We measure electron densities of N
e= (2.94+0.71
−1.03) × 103 cm−3, N
e= (1.47+0.60
−0.47) × 104 cm−3 and N
e= (3.16+1.66
−1.01) × 105 cm−3 for the regions emitting the narrow, broad and very broad components, respectively. We therefore calculate a total mass outflow rate of
M⊙ yr−1, similar to the range estimated for another compact radio source, PKS 1549−79. We estimate the total mass in the warm gas outflow is M
total= (8+3
−3) × 105 M⊙ with filling factors of ε= (4.4+1.8
−1.5) × 10−4 and ε= (1.6+0.7
−0.5) × 10−7 for the regions emitting the broad and very broad components, respectively. The total kinetic power in the warm outflow is
erg s−1. Taking the black hole properties published by Dasyra et al., we find that only a small fraction
of the available accretion power is driving the warm outflow in PKS 1345+12, which is significantly less than that currently required by the majority of quasar feedback models (∼5-10 per cent of L
bol), but similar to the recent suggestion of Hopkins & Elvis if a two-stage feedback model is implemented (∼0.5 per cent of L
bol). The models also predict that active galactic nuclei (AGN)-driven outflows will eventually remove the gas from the bulge of the host galaxy. Our observations show that the visible warm outflow in PKS 1345+12 is not currently capable of doing so. However, it is entirely possible that much of the outflow is either obscured by a dense and dusty natal cocoon and/or in cooler or hotter phases of the ISM. This result is important not just for studies of young Gigahertz-Peaked Spectrum/Compact Steep Spectrum radio sources, but for AGN in general.
Abstract
We present deep Gemini Multi-Object Spectrograph-South optical broad-band images for a complete sample of 20 Sloan Digital Sky Survey selected type II quasars taken from Zakamska et al., ...with redshifts in the range 0.3 < z < 0.41 and O iiiλ5007 emission-line luminosities . The images were taken with the aim of investigating the interaction status of the quasar host galaxies, in order to determine the significance of galaxy interactions in triggering nuclear activity. We find that 15 of our sample of 20 (75 per cent) show evidence for interaction in the form of tails, shells, fans, irregular features, amorphous haloes and double nuclei. The median surface brightness of the features is and the range is .
We find a similar rate of interaction signatures in the type II quasars as in a comparison sample of quiescent early-type galaxies at similar redshift (67 per cent) taken from Ramos Almeida et al. (RA11). However the surface brightness of the detected features is up to 2 mag brighter for the type II quasars than for the quiescent early types, which have surface brightnesses in the range . Despite the relatively small sample size, this may indicate that the mergers witnessed in the comparison sample galaxies could have different progenitors, or we may be viewing the interactions at different stages. We also compare our results with those of Ramos Almeida et al. (RA12) who made a similar analysis using a complete sample of radio-loud active galactic nuclei (AGN). They find a higher rate of interaction signatures in the radio-loud AGN (95 per cent) than the type II quasars, but a very similar range of surface brightnesses for the morphological features , possibly indicating a similarity in the types of triggering interactions.
The wide range of features detected in the type II quasar sample suggests that AGN activity can be triggered before, during or after the coalescence of the black holes, with six of the 20 objects (30 per cent) having double nuclei. Overall, the results presented here are consistent with the idea that galaxy interaction plays an important role in the triggering of quasar activity. We also use time-scale arguments to show that it is unlikely that most radio-quiet quasars cycle through a radio-loud phase as part of a single quasar triggering event.
We present deep Gemini Multi-Object Spectrograph South (GMOS-S)/Gemini optical broad-band images for a complete sample of 46 southern 2 Jy radio galaxies at intermediate redshifts (0.05 < z < 0.7). ...Based on them, we discuss the role of galaxy interactions in the triggering of powerful radio galaxies (PRGs). The high-quality observations presented here show for the first time that the overall majority of PRGs at intermediate redshifts (78-85 per cent) show peculiarities in their optical morphologies at relatively high levels of surface brightness (
;
). The observed morphological peculiarities include tails, fans, bridges, shells, dust lanes, irregular features, amorphous haloes and multiple nuclei. While the results for many of the galaxies are consistent with them being observed at, or after, the time of coalescence of the nuclei in a galaxy merger, we find that more than one-third of the sample are observed in a pre-coalescence phase of the merger, or following a close encounter between galaxies that will not necessarily lead to a merger. By dividing the sample into Weak-Line Radio Galaxies (WLRGs; 11 objects) and Strong-Line Radio Galaxies (SLRGs; 35 objects) we find that only 27 per cent of the former show clear evidence for interactions in their optical morphologies, in contrast to the SLRGs, of which at least 94 per cent appear interacting. This is consistent with the idea that many WLRGs are fuelled/triggered by the Bondi accretion of hot gas. However, the evidence for interactions and dust features in a fraction of them indicates that the accretion of cold gas cannot always be ruled out. Of the 28 per cent of the sample that display evidence for significant starburst activity, we find that 92 per cent present disturbed morphologies, following the same general trend as the total and SLRG samples. By comparing our PRGs with various samples of quiescent ellipticals from the literature, we conclude that the percentage of morphological disturbance that we find here exceeds that found for quiescent ellipticals when similar surface brightnesses are considered. Overall, our study indicates that galaxy interactions are likely to play a key role in the triggering of active galactic nuclei (AGN)/jet activity.
This paper is the second in a series in which we present intermediate-resolution, wide-wavelength coverage spectra for a complete sample of 14 compact radio sources, taken with the aim of ...investigating the impact of the nuclear activity on the circumnuclear interstellar medium (ISM) in the early stages of radio source evolution. In the first paper (Holt, Tadhunter & Morganti), we presented the kinematic results from the nuclear emission-line modelling and reported fast outflows in the circumnuclear gas. In this paper, we use the line fluxes to investigate the physical conditions and dominant ionization mechanisms of the emission-line gas. We find evidence for large electron densities and high reddening in the nuclear regions, particularly in the broader, blueshifted components. These results are consistent with the idea that the young, recently triggered radio sources still reside in dense and dusty cocoons deposited by the recent activity triggering event (merger/interaction). In addition, we find that the quiescent nuclear and extended narrow components are consistent with active galactic nucleus (AGN) photoionization, split between simple-slab AGN photoionization and mixed-medium photoionization models. For the nuclear broader and shifted components, the results are less clear. Whilst there are suggestions that the broader components may be closer to shock plus precursor models on the diagnostic diagrams, and that the electron temperatures and densities are high, we are unable to unambiguously distinguish the dominant ionization mechanism using the optical emission-line ratios. This is surprising given the strong evidence for jet–cloud interactions (broad emission lines, large outflow velocities and strong radio-optical alignments), which favours the idea that the warm gas has been accelerated in shocks driven by the radio lobes expanding through a dense cocoon of gas deposited during the triggering event.
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