Evolutionary unification in composite active galactic nuclei

Lípari, S.; Terlevich, Elena

doi:10.1111/j.1365-2966.2006.10215.x

Cited by 38 publications

(71 citation statements)

References 160 publications

(351 reference statements)

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“…According to the evolutionary model recently proposed by Lipari & Terlevich (2006), BAL quasars are young systems with composite outflows, and they are accompanied by absorption clouds. The radio-loud systems may be associated with the later stages of evolution, when jets have removed the clouds responsible for the generation of BALs.…”

Section: Discussionmentioning

confidence: 99%

FIRST-based survey of compact steep spectrum sources

Kunert-Bajraszewska¹,

Marecki²

2007

A&A

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Aims. Multifrequency VLBA observations of the final group of ten objects in a sample of FIRST-based compact steep spectrum (CSS) sources are presented. The sample was selected to investigate whether objects of this kind could be relics of radio-loud AGNs switched off at very early stages of their evolution or possibly to indicate intermittent activity. Methods. Initial observations were made using MERLIN at 5 GHz. The sources have now been observed with the VLBA at 1.7, 5 and 8.4 GHz in a snapshot mode with phase-referencing. The resulting maps are presented along with unpublished 8.4-GHz VLA images of five sources. Results. Some of the sources discussed here show a complex radio morphology and therefore a complicated past that, in some cases, might indicate intermittent activity. One of the sources studied -1045+352 -is known as a powerful radio and infrared-luminous broad absorption line (BAL) quasar. It is a young CSS object whose asymmetric two-sided morphology on a scale of several hundred parsecs, extending in two different directions, may suggest intermittent activity. The young age and compact structure of 1045+352 is consistent with the evolution scenario of BAL quasars. It has also been confirmed that the submillimetre flux of 1045+352 can be seriously contaminated by synchrotron emission.

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Section: Discussionmentioning

confidence: 99%

FIRST-based survey of compact steep spectrum sources

Kunert-Bajraszewska¹,

Marecki²

2007

A&A

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“…Such a particular phase of QSO activity has been claimed to be part of an evolutionary sequence of AGN (e.g. Sanders et al 1988a,b;Lipari 1994;Canalizo & Stockton 2000;Papadopoulos et al 2008;Lípari & Terlevich 2006, and references therein) as a short transition phase before the QSO becomes dominant. In this scenario HE 1029-1401 would have to be place at the end of a potential AGN evolutionary path, the QSO dominant phase.…”

Section: The Origin Of the Gasmentioning

confidence: 99%

Mapping the ionised gas around the luminous QSO HE 1029-1401: evidence for minor merger events?

Sánchez

Wisotzki²,

Jahnke

et al. 2010

A&A

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We present VIMOS integral field spectroscopy of the brightest radio-quiet QSO on the southern sky HE 1029-1401 at a redshift of z = 0.086. Standard decomposition techniques for broad-band imaging are extended to integral field data in order to deblend the QSO and host emission. We perform a tentative analysis of the stellar continuum, finding a young stellar population (<100 Myr) or a featureless continuum embedded in an old stellar population (10 Gyr) typical for a massive elliptical galaxy. The stellar velocity dispersion of σ * = 320 ± 90 km s −1 and the estimated black hole mass log(M BH /M ) = 8.7 ± 0.3 are consistent with the local M BH -σ * relation within the errors. For the first time, we map the two-dimensional ionised gas distribution and the gas velocity field around HE 1029-1401. While the stellar host morphology is purely elliptical, we find a highly structured distribution of ionised gas out to 16 kpc from the QSO. The gas is highly ionised solely by the QSO radiation and has a significantly lower metallicity than would be expected for the stellar mass of the host, indicating an external origin of the gas most likely due to minor mergers. We find a rotating gas disc around the QSO and a dispersion-dominated non-rotating gas component within the central 3 kpc. At larger distances the velocity field is heavily disturbed, which could be interpreted as another signature of past minor merger events. Alternatively, the arc-like structure seen in the ionised gas might also be indicative of a large-scale expanding bubble, centred on and possibly driven by the active nucleus.

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“…On top of that, by missing low-luminosity AGN (e.g., Stern et al 2005;Eckart et al 2010;Mateos et al 2013), IR-selection misses an evolution phase where AGN are believed to spend most of their life spans (e.g., Hopkins et al 2005Hopkins et al , 2006Fu et al 2010). Although currently in a low-luminosity phase, these AGN are believed to have induced strong feedback effect in the past in a quasar phase (e.g., Lipari et al 2005;Lípari & Terlevich 2006;Hopkins et al 2008;Maiolino et al 2012) and/or to do so at later times (for instance, induced by galaxy merger events, e.g., Hopkins et al 2008;Lípari et al 2009). It is therefore important to understand what the limitations are of each of the AGN selection techniques used in different spectral regimes.…”

Section: Introductionmentioning

confidence: 99%

The dependency of AGN infrared colour-selection on source luminosity and obscuration

Messias

Afonso

Salvato

et al. 2014

A&A

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Aims. This work addresses the AGN IR-selection dependency on intrinsic source luminosity and obscuration, in order to identify and characterise biases that could affect conclusions in studies. Methods. We study IR-selected AGN in the Chandra Deep Field South (CDFS) survey and in the Cosmological Survey (COSMOS). The AGN sample is divided into low and high X-ray luminosity classes and into unobscured (type-1) and obscured (type-2) classes by means of X-ray and optical spectroscopy data. Specifically in the X-ray regime, we adopt the intrinsic luminosity taking the estimated column density (N H ) into account. We also take the opportunity to highlight important differences resulting from adopting different methods of assessing AGN obscuration. Results. In agreement with previous studies, we also find that AGN IR-selection efficiency shows a decrease with decreasing source AGN X-ray luminosity. For the intermediate-luminosity AGN population (43.3 < ∼ log(L X [erg s −1 ]) < ∼ 44), the efficiency also worsens with increasing obscuration (N H ). The same sample also shows an evolution with cosmic time of the obscured fraction at the highest X-ray luminosities, independently of the adopted type-1/type-2 classification method. Conclusions. We confirm that AGN IR-selection is genuinely biased towards unobscured AGNe, but only at intermediate luminosities.At the highest luminosities, where AGN IR-selection is more efficient, there is no obscuration bias. We show that type-1 AGNe are intrinsically more luminous than type-2 AGNe only at z < ∼ 1.6, thus resulting in more type-1 AGN being selected when the IR survey is shallower. Based on this and other studies, we conclude that deep hard-X-ray coverages, high-resolution IR imaging, or a combination of IR and radio data are required to recover the lower luminosity obscured AGN population. In addition, wide IR surveys are needed to recover the rare powerful, obscured AGN population. Finally, when the James Webb Space Telescope comes online, the broad-band filters 2.0 µm, 4.4 µm, 7.7 µm, and 18 µm will be essential for disentangling AGN from non-AGN dominated SEDs at depths where spectroscopy becomes impractical.

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Evolutionary unification in composite active galactic nuclei

Cited by 38 publications

References 160 publications

FIRST-based survey of compact steep spectrum sources

FIRST-based survey of compact steep spectrum sources

Mapping the ionised gas around the luminous QSO HE 1029-1401: evidence for minor merger events?

The dependency of AGN infrared colour-selection on source luminosity and obscuration

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