Extreme ionised outflows are more common when the radio emission is compact in AGN host galaxies

Using a sample of 2922 z < 0.2, spectroscopically identified active galactic nuclei (AGN), we explore the relationship between radio size and the prevalence of extreme ionised outflows, as traced using broad [O III] emission-line profiles in spectra obtained by the Sloan Digital Sky Survey (SDSS). To classify radio sources as compact or extended, we combined a machine-learning technique for morphological classification with size measurements from two-dimensional Gaussian models to data from all-sky radio surveys. We find that the two populations have statistically different [O III] emission-line profiles; the compact sources tend to have the most extreme gas kinematics. When the radio emission is confined within 3″ (i.e. within the spectroscopic fibre or ≲5 kpc at the median redshift), the chance of observing broad [O III] emission-line components, which are indicative of very high velocity outflows and have a full width at half-maximum > 1000 km s−1, is twice as high. This difference is greatest for the highest radio luminosity bin of log[L1.4 GHz/W Hz−1] = 23.5−24.5 where the AGN dominate the radio emission; specifically, > 1000 km s−1 components are almost four times as likely to occur when the radio emission is compact in this subsample. Our follow-up ≈0.3″–1″ resolution radio observations for a subset of targets in this luminosity range reveal that radio jets and lobes are prevalent, and suggest that compact jets might be responsible for the stronger outflows in the wider sample. Our results are limited by the available relatively shallow all-sky radio surveys, but forthcoming surveys will provide a more complete picture of the connection between radio emission and outflows. Overall, our results add to the growing body of evidence that ionised outflows and compact radio emission in highly accreting “radiative” AGN are closely connected, possibly as a result of young or weak radio jets.

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On the Environments of Giant Radio Galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab297 ◽

2021 ◽

Author(s):

Ting-Wen Lan ◽

J Xavier Prochaska

Keyword(s):

Large Scale ◽

Radio Galaxies ◽

Sloan Digital Sky Survey ◽

Host Galaxies ◽

Homogeneous Sample ◽

Large Scale Structures ◽

Radio Jets ◽

Sky Survey ◽

Scale Structures ◽

Control Samples

Abstract We test the hypothesis that environments play a key role in enabling the growth of enormous radio structures spanning more than 700 kpc, an extreme population of radio galaxies called giant radio galaxies (GRGs). To achieve this, we explore (1) the relationships between the occurrence of GRGs and the surface number density of surrounding galaxies, including satellite galaxies and galaxies from neighboring halos, as well as (2) the GRG locations towards large-scale structures. The analysis is done by making use of a homogeneous sample of 110 GRGs detected from the LOFAR Two-metre Sky Survey in combination with photometric galaxies from the DESI Legacy Imaging Surveys and a large-scale filament catalog from the Sloan Digital Sky Survey. Our results show that the properties of galaxies around GRGs are similar with that around the two control samples, consisting of galaxies with optical colors and luminosity matched to the properties of the GRG host galaxies. Additionally, the properties of surrounding galaxies depend on neither their relative positions to the radio jet/lobe structures nor the sizes of GRGs. We also find that the locations of GRGs and the control samples with respect to the nearby large-scale structures are consistent with each other. These results demonstrate that there is no correlation between the GRG properties and their environments traced by stars, indicating that external galaxy environments are not the primary cause of the large sizes of the radio structures. Finally, regarding radio feedback, we show that the fraction of blue satellites does not correlate with the GRG properties, suggesting that the current epoch of radio jets have minimal influence on the nature of their surrounding galaxies.

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Tracing Metallicity in High Redshift Quasars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310000517 ◽

2009 ◽

Vol 5 (S265) ◽

pp. 183-184

Author(s):

Leah E. Simon ◽

Fred Hamann

Keyword(s):

Star Formation ◽

Emission Line ◽

Gas Phase ◽

High Redshift ◽

Ultra Violet ◽

Far Infrared ◽

Sloan Digital Sky Survey ◽

Host Galaxies ◽

Composite Spectra ◽

Sky Survey

AbstractWe present two ongoing studies of gas phase abundances around high redshift quasars. First, we examine broad emission line (BEL) metallicities for 29 quasars with 2.3 < z < 4.6 and far-infrared (far-IR) luminosities (LFIR) from 1013.4 to ≤ 1012.2 L⊙, corresponding to star formation rates (SFRs) of 6740 to ≤ 1360 M⊙ yr−1. Quasar samples sorted by LFIR might represent an evolutionary sequence if SFRs in quasar hosts generally diminish across quasar lifetimes. We create three composite spectra from rest-frame ultra-violet Sloan Digital Sky Survey spectra with increasing far-IR luminosity. We measure the N V(λ1240)/C IV(λ1550) and Si IV(λ1397)+O IV](λ1402)/C IV(λ1550) emission line flux ratios for each composite and find uniformly high (~5-10 times solar) metallicities for the three composites, and no evidence for changes in metal enrichment with changes in ongoing SFR. Second, we present preliminary results from the largest ever survey of high resolution associated absorption line (AAL) region metallicities and physical properties in a sample of high redshift (z > 3) quasars. This includes five quasars with previously known AALs at z > 4 and two well measured z ~3 quasars with unusually rich absorption spectra. We determine well-constrained metallicities of about twice solar for five AAL systems. We find a range of lower limits for AAL metallicities in the z > 4 quasars from 1/100ths solar to 3 times solar. Overall, these results for typically super-solar gas-phase metallicities near quasars are consistent with evolutionary schemes where the major episodes of star formation in the host galaxies occur before the visibly luminous quasar phase. High SFRs (comparable to ULIRGs) in the host galaxies are not clearly linked to younger or chemically less mature quasar environments.

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The impact of AGN on their host galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314004098 ◽

2013 ◽

Vol 9 (S304) ◽

pp. 284-290

Author(s):

C. M. Harrison

Keyword(s):

High Mass ◽

Host Galaxies ◽

Gas Kinematics ◽

Radio Jets ◽

Black Hole Growth ◽

Plausible Mechanism ◽

Massive Halos ◽

Hole Growth ◽

The Impact

AbstractIn these proceedings I briefly: (1) review the impact (or “feedback”) that active galactic nuclei (AGN) are predicted to have on their host galaxies and larger scale environment, (2) review the observational evidence for or against these predictions and (3) present new results on ionised outflows in AGN. The observational support for the “maintenance mode” of feedback is strong (caveat the details); AGN at the centre of massive halos appear to be regulating the cooling of hot gas, which could in turn control the levels of future star formation (SF) and black hole growth. In contrast, direct observational support for more rapid forms of feedback, which dramatically impact on SF (i.e., the “quasar mode”), remains elusive. From a systematic study of the spectra of ≈24 000 AGN we find that extreme ionised gas kinematics are common, and are most prevalent in radio bright AGN (L1.4 GHz > 103 W Hz−1). Follow-up IFU observations have shown that these extreme gas kinematics are extended over kilo-parsec scales. However, the co-existence of high-levels of SF, luminous AGN activity and radio jets raises interesting questions on the primary drivers and impact of these outflows. Galaxy-wide, high-mass outflows are being observed in an increasing number of AGN and are a plausible mechanism for the depletion of gas; however, there is still much work to be done to determine the physical processes that drive these outflows and to measure the level of impact that they have on their host galaxies.

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Ionized gas kinematics and luminosity profiles of Low-z Lyman Alpha Blobs

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320001489 ◽

2019 ◽

Vol 15 (S359) ◽

pp. 413-414

Author(s):

María P. Agüero ◽

Rubén Díaz ◽

Mischa Schirmer

Keyword(s):

Emission Line ◽

Galactic Nuclei ◽

Host Galaxies ◽

Ionized Gas ◽

Lyman Alpha ◽

Gas Kinematics ◽

The Universe ◽

Very High ◽

The Continuum

AbstractThis work is focused on the characterization of the Seyfert-2 galaxies hosting very large, ultra-luminous narrow-line regions (NLRs) at redshifts z = 0.2−0.34. With a space density of 4.4 Gcp−3 at z ∼ 0.3, these “Low Redshift Lyman-α Blob” (LAB) host galaxies are amongst the rarest objects in the universe, and represent an exceptional and short-lived phenomenon in the life cycle of active galactic nuclei (AGNs). We present the study of GMOS spectra for 13 LAB galaxies covering the rest frame spectral range 3700–6700 Å. Predominantly, the [OIII]λ5007 emission line radial distribution is as widespread as that of the continuum one. The emission line profiles exhibit FWHM between 300–700 Km s−1. In 7 of 13 cases a broad kinematical component is detected with FWHM within the range 600–1100 Km s−1. The exceptionally high [OIII]λ5007 luminosity is responsible for very high equivalent width reaching 1500 Å at the nucleus.

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A Method of Identifying AGNs Based on Emission-Line Excess and the Nature of Low-Luminosity AGNs in the Sloan Digital Sky Survey. I. A New Method

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/64.2.36 ◽

2012 ◽

Vol 64 (2) ◽

pp. 36 ◽

Cited By ~ 5

Author(s):

Masayuki Tanaka

Keyword(s):

Emission Line ◽

Sloan Digital Sky Survey ◽

New Method ◽

Sky Survey

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THE SLOAN DIGITAL SKY SURVEY REVERBERATION MAPPING PROJECT: AN INVESTIGATION OF BIASES IN C iv EMISSION LINE PROPERTIES

The Astrophysical Journal Supplement Series ◽

10.3847/0067-0049/224/2/14 ◽

2016 ◽

Vol 224 (2) ◽

pp. 14 ◽

Cited By ~ 19

Author(s):

K. D. Denney ◽

Keith Horne ◽

Yue Shen ◽

W. N. Brandt ◽

Luis C. Ho ◽

...

Keyword(s):

Emission Line ◽

Sloan Digital Sky Survey ◽

Reverberation Mapping ◽

Sky Survey

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The optically selected 1.4-GHz quasar luminosity function below 1 mJy

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa112 ◽

2020 ◽

Vol 492 (4) ◽

pp. 5297-5312 ◽

Cited By ~ 1

Author(s):

Eliab Malefahlo ◽

Mario G Santos ◽

Matt J Jarvis ◽

Sarah V White ◽

Jonathan T L Zwart

Keyword(s):

Luminosity Function ◽

Significant Contribution ◽

Detection Threshold ◽

Simulated Data ◽

Sloan Digital Sky Survey ◽

Radio Luminosity ◽

Host Galaxies ◽

Star Forming ◽

Sky Survey ◽

Radio Luminosity Function

ABSTRACT We present the radio luminosity function (RLF) of optically selected quasars below 1 mJy, constructed by applying a Bayesian-fitting stacking technique to objects well below the nominal radio flux density limit. We test the technique using simulated data, confirming that we can reconstruct the RLF over three orders of magnitude below the typical 5σ detection threshold. We apply our method to 1.4-GHz flux densities from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey, extracted at the positions of optical quasars from the Sloan Digital Sky Survey over seven redshift bins up to z = 2.15, and measure the RLF down to two orders of magnitude below the FIRST detection threshold. In the lowest redshift bin (0.2 < z < 0.45), we find that our measured RLF agrees well with deeper data from the literature. The RLF for the radio-loud quasars flattens below $\log _{10}[L_{1.4}/{\rm W\, Hz}^{-1}] \approx 25.5$ and becomes steeper again below $\log _{10}[L_{1.4}/{\rm W\, Hz}^{-1}] \approx 24.8$, where radio-quiet quasars start to emerge. The radio luminosity where radio-quiet quasars emerge coincides with the luminosity where star-forming galaxies are expected to start dominating the radio source counts. This implies that there could be a significant contribution from star formation in the host galaxies, but additional data are required to investigate this further. The higher redshift bins show a similar behaviour to the lowest z bin, implying that the same physical process may be responsible.

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An ASKAP survey for H i absorption towards dust-obscured quasars

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2452 ◽

2019 ◽

Vol 489 (4) ◽

pp. 4926-4943 ◽

Cited By ~ 6

Author(s):

M Glowacki ◽

J R Allison ◽

V A Moss ◽

E K Mahony ◽

E M Sadler ◽

...

Keyword(s):

Galaxy Evolution ◽

Spectral Energy Distribution ◽

Galactic Nuclei ◽

Host Galaxy ◽

Spectral Energy ◽

Neutral Medium ◽

Host Galaxies ◽

Gas Kinematics ◽

Neutral Gas

ABSTRACT Obscuration of quasars by accreted gas and dust, or dusty intervening galaxies, can cause active galactic nuclei (AGN) to be missed in optically selected surveys. Radio observations can overcome this dust bias. In particular, radio surveys searching for H i absorption inform us on how the AGN can impact on the cold neutral gas medium within the host galaxy, or the population of intervening galaxies through the observed line of sight gas kinematics. We present the results of an H i absorption line survey at 0.4 < z < 1 towards 34 obscured quasars with the Australian SKA Pathfinder (ASKAP) commissioning array. We detect three H i absorption lines, with one of these systems previously unknown. Through optical follow-up for two sources, we find that in all detections the H i gas is associated with the AGN, and hence that these AGN are obscured by material within their host galaxies. Most of our sample are compact, and in addition, are either gigahertz peaked spectrum (GPS), or steep spectrum (CSS) sources, both thought to represent young or recently re-triggered radio AGN. The radio spectral energy distribution classifications for our sample agree with galaxy evolution models in which the obscured AGN has only recently become active. Our associated H i detection rate for GPS and compact SS sources matches those of other surveys towards such sources. We also find shallow and asymmetric H i absorption features, which agrees with previous findings that the cold neutral medium in compact radio galaxies is typically kinematically disturbed by the AGN.

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