On the morphological dichotomies observed in the powerful radio galaxies

Miraghaei, H.; Best, P. N.

doi:10.1088/1742-6596/869/1/012078

Cited by 25 publications

(57 citation statements)

References 11 publications

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“…The FRI/FRII classification cannot be directly mapped onto the HERG/LERG classification: while HERGs are typically powerful FRIIs, LERGs can be either FRIs or low power FRIIs. The low power FRII type radio galaxies occupy the FRI region in the Ledlow-Owen diagram (see, e.g., Best 2009;Miraghaei & Best 2017). In fact, based on Figure 5 in Miraghaei & Best (2017) it may seem that the separation occurs between the excitation classes rather than the morphological types of radio galaxies.…”

Section: Radio Properties Of Hymors and The Ledlow-owen Diagrammentioning

confidence: 99%

“…The low power FRII type radio galaxies occupy the FRI region in the Ledlow-Owen diagram (see, e.g., Best 2009;Miraghaei & Best 2017). In fact, based on Figure 5 in Miraghaei & Best (2017) it may seem that the separation occurs between the excitation classes rather than the morphological types of radio galaxies. A similar conclusion has recently been reached by Capetti et al (2017) who used the same base data sample as Miraghaei & Best (2017), but see the discussion in Singal & Rajpurohit (2014) on the validity and Turner & Shabala (2015) on tightness of and environmental impact on the Ledlow-Owen correlation.…”

Section: Radio Properties Of Hymors and The Ledlow-owen Diagrammentioning

confidence: 99%

“…In fact, based on Figure 5 in Miraghaei & Best (2017) it may seem that the separation occurs between the excitation classes rather than the morphological types of radio galaxies. A similar conclusion has recently been reached by Capetti et al (2017) who used the same base data sample as Miraghaei & Best (2017), but see the discussion in Singal & Rajpurohit (2014) on the validity and Turner & Shabala (2015) on tightness of and environmental impact on the Ledlow-Owen correlation. Here, we find that our HyMoRS candidates can be both low-and high-excitation radio galaxies, though a study with larger number statistics is needed to understand how common each is.…”

Section: Radio Properties Of Hymors and The Ledlow-owen Diagrammentioning

confidence: 99%

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Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

Kapińska

Terentev²,

Wong

et al. 2017

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Hybrid morphology radio sources (HyMoRS) are a rare type of radio galaxy that display different Fanaroff-Riley classes on opposite sides of their nuclei. To enhance the statistical analysis of HyMoRS, we embarked on a largescale search of these sources within the international citizen science project, Radio Galaxy Zoo (RGZ). Here, we present 25 new candidate hybrid morphology radio galaxies. Our selected candidates are moderate power radio galaxies (L 4.7 10 median 24=´W Hz −1 sr −1 ) at redshifts z 0.14 1.0 < < . Hosts of nine candidates have spectroscopic observations, of which six are classified as quasars, one as high-and two as low-excitation galaxies. Two candidate HyMoRS are giant ( 1 > Mpc) radio galaxies, one resides at the center of a galaxy cluster, and one is hosted by a rare green bean galaxy. Although the origin of the hybrid morphology radio galaxies is still unclear, this type of radio source starts depicting itself as a rather diverse class. We discuss hybrid radio morphology formation in terms of the radio source environment (nurture) and intrinsically occurring phenomena (nature; activity cessation and amplification), showing that these peculiar radio galaxies can be formed by both mechanisms. While high angular resolution follow-up observations are still necessary to confirm our candidates, we demonstrate the efficacy of the RGZ in the pre-selection of these sources from all-sky radio surveys, and report the reliability of citizen scientists in identifying and classifying complex radio sources.

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Section: Radio Properties Of Hymors and The Ledlow-owen Diagrammentioning

confidence: 99%

Section: Radio Properties Of Hymors and The Ledlow-owen Diagrammentioning

confidence: 99%

Section: Radio Properties Of Hymors and The Ledlow-owen Diagrammentioning

confidence: 99%

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Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

Kapińska

Terentev²,

Wong

et al. 2017

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“…Recently, Miraghaei & Best (2017) also selected compact RGs from the BH12 sample. They selected single-component FIRST sources, brighter than 40 mJy, in the redshift range 0.03>z>0.1.…”

Section: Sample Selectionmentioning

confidence: 99%

“…In particular, these surveys allow us to identify large numbers of radio sources, to obtain spectroscopic redshifts, and to determine the properties of their hosts. Several studies (e.g., Best et al 2005;Baldi & Capetti 2010;Best & Heckman 2012;Mingo et al 2016;Miraghaei & Best 2017) have used the extensive available multi-frequency information to analyze the properties of the population of low-redshift low-power radio AGN. In particular, Best & Heckman (2012) defined diagnostics to isolate galaxies in which the radio emission is produced by an active nucleus.…”

Section: Introductionmentioning

confidence: 99%

FR0CAT: a FIRST catalog of FR 0 radio galaxies

Baldi

Capetti

Massaro

2017

A&A

104

156

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With the aim of exploring the properties of the class of FR 0 radio galaxies, we selected a sample of 108 compact radio sources, called FR0CAT, by combining observations from the NVSS, FIRST, and SDSS surveys. We included in the catalog sources with redshift ≤ 0.05, with a radio size 5 kpc, and with an optical spectrum characteristic of low-excitation galaxies. Their radio luminosities at 1.4 GHz are in the range 10 38 νL 1.4 10 40 erg s −1 . The FR0CAT hosts are mostly (86%) luminous (−21 M r −23) red early-type galaxies with black hole masses 10 8 M BH 10 9 M ⊙ . These properties are similar to those seen for the hosts of FR I radio galaxies, but they are on average a factor ∼1.6 less massive. The number density of FR0CAT sources is ∼5 times higher than that of FR Is, and thus they represent the dominant population of radio sources in the local Universe. Different scenarios are considered to account for the smaller sizes and larger abundance of FR 0s with respect to FR Is. An age-size scenario that considers FR 0s as young radio galaxies that will all eventually evolve into extended radio sources cannot be reconciled with the large space density of FR 0s. However, the radio activity recurrence, with the duration of the active phase covering a wide range of values and with short active periods strongly favored with respect to longer ones, might account for their large density number. Alternatively, the jet properties of FR 0s might be intrinsically different from those of the FR Is, the former class having lower bulk Lorentz factors, possibly due to lower black hole spins. Our study indicates that FR 0s and FR I/IIs can be interpreted as two extremes of a continuous population of radio sources that is characterized by a broad distribution of sizes and luminosities of their extended radio emission, but shares a single class of host galaxies.

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The relation between the radio emission of the core and host galaxy properties in Fanaroff–Riley type II radio galaxies

Mazoochi

Miraghaei

Riazi

2022

Publ. Astron. Soc. Aust.

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We study the radio power of the core and its relation to the optical properties of the host galaxy in samples of high-excitation (HERG) and low-excitation (LERG) Fanaroff–Riley type II (FRII) radio galaxies. The radio galaxy sample is divided into two groups of core/non-core FRII, based on the existence of strong, weak or lack of single radio core component. We show that FRII LERGs with radio emission of the core have significantly higher [O III] line luminosities compared to the non-core LERG FRIIs. There is no significant difference between the hosts of the core and non-core FRIIs of LERG type in galaxy sizes, concentration indices, star formation rates, 4000-Å break strengths, colours, black hole masses, and black hole to stellar masses. We show that the results are not biased by the stellar masses, redshifts, and angular sizes of the radio galaxies. We argue that the detection of higher [O III] luminosities in the core FRIIs may indicate the presence of higher amounts of gas, very close to the active galactic nuclei (AGN) nucleus in the core FRIIs compared to the non-core FRIIs or may result from the interaction of the radio jets with this gas. The core and non-core FRIIs of the HERG type show no significant differences perhaps due to our small sample size. The effect of relativistic beaming on the radio luminosities and the contribution of restating AGN activity have also been considered.

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On the morphological dichotomies observed in the powerful radio galaxies

Cited by 25 publications

References 11 publications

Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

FR0CAT: a FIRST catalog of FR 0 radio galaxies

The relation between the radio emission of the core and host galaxy properties in Fanaroff–Riley type II radio galaxies

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