ON THE POPULATIONS OF RADIO GALAXIES WITH EXTENDED MORPHOLOGY AT<i>z</i>&lt; 0.3

Lin, Yen-Ting; Shen, Yue; Strauss, Michael A.; Richards, Gordon T.; Lunnan, R.

doi:10.1088/0004-637x/723/2/1119

Cited by 61 publications

(60 citation statements)

References 66 publications

(87 reference statements)

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“…Similar to the results of Best (2009) and Lin et al (2010), we found that while there may be a general trend for FR I sources to reside below the line proposed by Ledlow & Owen (1996), it is by no means an absolute separation. Specifically, we found that for the visual-bent sample, 81% of the sources we visually identified as FR I sources are also FR I sources according to the criteria of Ledlow & Owen (1996).…”

Section: Determining Radio Power and Fr Morphologysupporting

confidence: 89%

Galaxy Cluster Environments of Radio Sources

Wing¹,

Blanton²

2011

The Astronomical Journal

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Using the Sloan Digital Sky Survey (SDSS) and the Faint Images of the Radio Sky at Twenty Centimeters (FIRST) catalogs, we examined the optical environments around double-lobed radio sources. Previous studies have shown that multi-component radio sources exhibiting some degree of bending between components are likely to be found in galaxy clusters. Often this radio emission is associated with a cD-type galaxy at the center of a cluster. We cross-correlated the SDSS and FIRST catalogs and measured the richness of the cluster environments surrounding both bent and straight multi-component radio sources. This led to the discovery and classification of a large number of galaxy clusters out to a redshift of z ∼ 0.5. We divided our sample into smaller subgroups based on their optical and radio properties. We find that FR I radio sources are more likely to be found in galaxy clusters than FR II sources. Further, we find that bent radio sources are more often found in galaxy clusters than non-bent radio sources. We also examined the environments around single-component radio sources and find that single-component radio sources are less likely to be associated with galaxy clusters than extended, multi-component radio sources. Bent, visually selected sources are found in clusters or rich groups ∼78% of the time. Those without optical hosts in SDSS are likely associated with clusters at even higher redshifts, most with redshifts of z > 0.7.

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Section: Determining Radio Power and Fr Morphologysupporting

confidence: 89%

Galaxy Cluster Environments of Radio Sources

Wing¹,

Blanton²

2011

The Astronomical Journal

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“…Indeed, in using Monte Carlo simulations to test whether observed samples of radio galaxies can be random selections of elliptical galaxies, Scarpa & Urry (2001) found that the two FR classes are hosted by ellipticals extracted from the same population. Also, the Owen-Ledlow diagrams of radio samples in later studies are not found to be as sharply divided between the two classes as originally found and there is non-insignificant number of FR-IIs below the canonical dividing line (Ledlow & Owen 1996;Lin et al 2010). These below-line FR-IIs, which are also found to be compact in physical size, have been speculated as being FR-IIs that are likely to evolve into FR-Is as their low-power jets get frustrated in interactions with the interstellar medium (ISM) of the host galaxy (Kaiser & Best 2007).…”

Section: The Owen-ledlow Diagrammentioning

confidence: 55%

Understanding the Fanaroff–riley Radio Galaxy Classification

Saripalli

2012

The Astronomical Journal

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A simple, yet profoundly far-reaching classification scheme based on extended radio morphologies of radio galaxies, the Fanaroff-Riley (FR) classification has been a cornerstone in our understanding of radio galaxies. Over the decades since the recognition that there are two basic types of radio galaxy morphologies, there have been several findings in different wavebands that have reported properties on different scales. Although it is realized that there may be intrinsic as well as external causes, an overarching view of how we may understand the two morphological types is missing. With the radio-power-absolute-magnitude relation (the Owen-Ledlow diagram) as a backdrop, we review and develop an understanding of the two radio galaxy types in light of what is known about them. We have for the first time included the dust properties of the two FR classes together with the relative orientations of dust, host major axis, and the radio axis to present a qualitative framework within which to understand the conditions under which they form. We discuss how the host elliptical and its history can explain the distribution of radio galaxies in the Owen-Ledlow diagram. The mass of the host elliptical galaxy is a crucial player in deciding what type of a radio galaxy it can host in what conditions. Benign conditions, characterized by natural evolutionary processes, most easily give rise to FR-I-type sources in ellipticals of all mass regimes, whereas with FR-IIs we reason that it is hard to form them without mergers. In undisturbed conditions elliptical galaxies appear to acquire stable states where the black hole axis settles along the host minor axis. With the steady conditions and the continuous supply of ambient gas, the FR-Is in principle may be powered for a long time. Aided by mergers and interactions, low-mass ellipticals more easily form FR-II-type sources than more massive hosts. LEG FR-IIs may include dying as well as restarted FR-II radio galaxies.

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“…There is also uncertainty surrounding the exact physical mechanism that turns energy from accreted material into well-collimated jets, and why some systems show no jets at all. Lin et al (2010) find that different radio morphologies are more dependent on the accretion rate than the galaxy's structure, with highlyextended, lobe-dominated radio galaxies having higher accretion rates than their less-extended counterparts. Furthermore, the work of Fernandes et al (2011) indicates that there is a minimum accretion rate for a given radio power, suggesting that there is a maximum efficiency with which the black hole is able to produce jets from infalling material.…”

Section: Radio Emission From Agnmentioning

confidence: 88%

Radio-quiet quasars in the VIDEO survey: evidence for AGN-powered radio emission at S1.4 GHz < 1 mJy

White

Jarvis

Häußler

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Understanding the interplay between black-hole accretion and star formation, and how to disentangle the two, is crucial to our understanding of galaxy formation and evolution. To investigate, we use a combination of optical and near-infrared photometry to select a sample of 74 quasars from the VISTA Deep Extragalactic Observations (VIDEO) Survey, over 1 deg 2 . The depth of VIDEO allows us to study very low accretion rates and/or lower-mass black holes, and 26 per cent of the candidate quasar sample has been spectroscopically confirmed. We use a radio-stacking technique to sample below the nominal flux-density threshold using data from the Very Large Array at 1.4 GHz and find, in agreement with other work, that a power-law fit to the quasar-related radio source counts is inadequate at low flux density. By comparing with a control sample of galaxies (where we match in terms of stellar mass), and by estimating the star formation rate, we suggest that this radio emission is predominantly caused by accretion activity rather than star-formation activity.

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ON THE POPULATIONS OF RADIO GALAXIES WITH EXTENDED MORPHOLOGY ATz< 0.3

Cited by 61 publications

References 66 publications

Galaxy Cluster Environments of Radio Sources

Galaxy Cluster Environments of Radio Sources

Understanding the Fanaroff–riley Radio Galaxy Classification

Radio-quiet quasars in the VIDEO survey: evidence for AGN-powered radio emission at S1.4 GHz < 1 mJy

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