A 20 CM VLA Survey of Abell clusters of galaxies. 4: The radio sample and cluster properties

Ledlow, Michael J.; Owen, F. N.

doi:10.1086/117328

Cited by 99 publications

(90 citation statements)

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“…The authors find that the surface density distribution of radio galaxies with log (P 1.4 GHz ) > 23.23 is more centrally concentrated than an expected King model distribution of cluster galaxies. Ledlow & Owen (1995) argue that the central concentration of radio galaxies in clusters is a direct result of (1) clusters having luminous host galaxies residing in their cores and (2) more luminous galaxies having a higher probability of hosting a radio source (Ledlow & Owen 1996). Our radio galaxy AGN fraction within 0.5 Mpc of the cluster center is ∼6%, consistent with their estimated fraction (∼8%) of elliptical galaxies hosting radio sources (see Figure 6 in Ledlow & Owen 1995).…”

Section: Comparison To Other Cluster Agn Studiessupporting

confidence: 84%

“…We also require radio observations to detect radio galaxies with P 1.4 GHz 3 × 10 23 W Hz −1 across the entire survey. Along with our well-defined cluster sample, our multi-wavelength approach to identify cluster AGN differs from many previous studies (e.g., Ledlow & Owen 1995;Martini et al 2007) which use X-ray or radio observations, but not both, to detect these objects in only one waveband. Table 1 lists our 11 z = 0.2-0.4 "Road to Coma" clusters, their redshifts, Chandra observational details (ObsID, ACIS aimpoint, exposure time, ICM temperature, flux, and luminosity limits), as well as Very Large Array (VLA) 1.4 GHz radio details.…”

Section: The "Road To Coma" Samplementioning

confidence: 99%

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X-Ray Point Sources and Radio Galaxies in Clusters of Galaxies

Hart

Stocke

Hallman

2009

ApJ

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Using Chandra imaging spectroscopy and Very Large Array L-band maps, we have identified radio galaxies at P (1.4 GHz) 3 × 10 23 W Hz −1 and X-ray point sources (XPSs) at L (0.3-8 keV) 10 42 erg s −1 in 11 moderate redshift (0.2 < z < 0.4) clusters of galaxies. Each cluster is uniquely chosen to have a total mass similar to predicted progenitors of the present-day Coma Cluster. Within a projected radius of 1 Mpc we detect 20 radio galaxies and 8 XPSs (three sources are detected in both X-ray and radio) confirmed to be cluster members above these limits. Of these, 75% are detected within 500 kpc (projected) of the cluster center. This result is inconsistent with a random selection from bright, red sequence ellipticals at the >99.999% level. We suggest that these active galactic nuclei (AGNs) are triggered somehow by the intracluster medium (ICM), perhaps similar to the Bondi accretion model of Allen et al. All but one of the XPSs are hosted by luminous ellipticals which otherwise show no other evidence for AGN activity. These objects are unlikely to be highly obscured AGN since there is no evidence for large amounts of X-ray or optical absorption. One XPS, in addition to possessing a pure absorption-line optical spectrum, has a large excess of light blueward of the Ca ii H&K break that could be nonthermal emission; a second XPS host galaxy probably has excess blue light. The most viable model for these sources are low-luminosity BL Lac Objects, similar to the high-energy-peaked BL Lacs (HBLs) discovered in abundance in serendipitous X-ray surveys. The expected numbers of lower luminosity FR 1 radio galaxies and HBLs in our sample converge to suggest that very deep radio and X-ray images of rich clusters will detect AGN (either X-ray or radio emitting or both) in a large fraction of bright elliptical galaxies in the inner 500 kpc. Because both the radio galaxies and the XPSs possess relativistic jets, they (and, by extension, the entire radio luminosity function) can inject heat into the ICM. Using the most recent scalings of P jet ∝ L 0.5 r from Bîrzan et al., radio sources weaker than our luminosity limit probably contribute the majority of the heat to the ICM. Also, because these heat sources move around the cluster, AGN heating is distributed rather evenly. If a majority of ICM heating is due to large numbers of low-power radio sources, triggered into activity by the increasing ICM density as they move inward, this may be the feedback mechanism necessary to stabilize cooling in cluster cores.

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Section: Comparison To Other Cluster Agn Studiessupporting

confidence: 84%

Section: The "Road To Coma" Samplementioning

confidence: 99%

X-Ray Point Sources and Radio Galaxies in Clusters of Galaxies

Hart

Stocke

Hallman

2009

ApJ

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“…12 However, >80% of those RGs that are in clusters lie within 20% of the virial radius from the cluster center, consistent with previous findings that RGs are centrally concentrated in clusters (e.g., Ledlow & Owen 1995;Lin & Mohr 2007).…”

Section: Environments Of Extended Radio Galaxiessupporting

confidence: 83%

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

Lin

Shen

Strauss

et al. 2010

ApJ

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Extended extragalactic radio sources have traditionally been classified into Fanaroff & Riley (FR) I and II types, based on the ratio r s of the separation S between the brightest regions on either sides of the host galaxy and the total size T of the radio source (r s ≡ S/T ). In this paper, we examine the distribution of various physical properties as a function of r s of 1040 luminous (L L * ) extended radio galaxies (RGs) at z < 0.3 selected with well-defined criteria from the SDSS, NVSS, and FIRST surveys. About 2/3 of the RGs are lobe dominated (LD) and 1/3 have prominent jets. If we follow the original definition of the FR types, i.e., a division based solely on r s , FR I and FR II RGs overlap in their host galaxy properties. However, the rare LD sources with r s 0.8 and [O iii] λ5007 line luminosity > 10 6 L are markedly different on average from the rest of the RGs, in the sense that they are hosted in lower mass galaxies, live in relatively sparse environments, and likely have higher accretion rates onto the central supermassive black hole (SMBH). Thus, these high emission line luminosity, high-r s LD RGs, and the rest of RGs form a well-defined dichotomy. Motivated by the stark differences in the nuclear emission line properties of the RG subsamples, we suggest that the accretion rate onto the SMBH may play the primary role in creating the different morphologies. At relatively high accretion rates, the accretion system may produce powerful jets that create the "classical double" morphology (roughly corresponding to the LD sources with r s 0.8 and emission lines); at lower accretion rates, the jets from a radiatively inefficient accretion flow generate radio lobes without apparent "hot spots" at the edge (corresponding to the majority of LD sources). At slightly lower accretion rates and in galaxies with dense galactic structure, sources with prominent jets result. It is possible that while the high accretion rate systems could affect sub-Mpc scale environments, the jets from lower accretion rate systems may efficiently suppress activity within the host galaxies.

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“…From our VLA 20cm survey of > 500 Abell clusters (Ledlow & Owen 1995a;Owen, White, & Ge 1993;Owen, White, & Burns 1992), we have found one clearly disk-dominated galaxy with radio morphology resembling the powerful FR I radio sources. The survey was statistically complete to 10 23 h −2 75 W Hz −1 out to z=0.09 though many sources were detected at lower redshifts with radio luminosities below this cutoff, including a number of spiral/S0 galaxies.…”

Section: Introductionmentioning

confidence: 89%

An Unusual Radio Galaxy in Abell 428: A Large, Powerful FR I Source in a Disk‐dominated Host

Ledlow

Owen

Keel

1998

ApJ

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We report the discovery of a powerful (∼ 10 24 h −2 75 W Hz −1 at 20cm) FR I radio source in a highly flattened disk-dominated galaxy. Half of the radio flux from this source is concentrated within the host galaxy, with the remainder in a pair of nearly symmetrical lobes with total extent ∼ 200 kpc nearly perpendicular to the disk. The traditional wisdom maintains that powerful, extended radio sources are found only in ellipticals or recent merger events. We report B, R, J, and K imaging, optical spectroscopy, a rotation curve, an IRAS detection, and a VLA 20 cm image for this galaxy, 0313-192. The optical and near infrared images clearly show a disk. We detect apparent spiral arms in a deep B band exposure, and a dust-lane from a higher resolution B band image. The reddened nucleus is consistent with extinction by a similar dust-lane. The optical spectrum suggests a central AGN and some evidence of a starburst, with both the AGN and central starlight appearing substantially reddened (perhaps by the optical dust-lane). From analysis of the extended line emission in [OIII] and Hα, we derive a rotation curve consistent with an early-type, dusty spiral seen edge-on. From the IRAS detection at 60 and 100µm we find that the ratio of Far IR to radio flux places this object firmly as a radio galaxy (i.e. the radio emission is not powered by star formation). The radio structure suggests that the radio source in this galaxy is related to the same physical mechanisms present in jet-fed powerful radio sources, and that such powerful, extended sources can (albeit extremely rarely) occur in a disk-dominated host.

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A 20 CM VLA Survey of Abell clusters of galaxies. 4: The radio sample and cluster properties

Cited by 99 publications

References 1 publication

X-Ray Point Sources and Radio Galaxies in Clusters of Galaxies

X-Ray Point Sources and Radio Galaxies in Clusters of Galaxies

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

An Unusual Radio Galaxy in Abell 428: A Large, Powerful FR I Source in a Disk‐dominated Host

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