The Molonglo Reference Catalog 1 Jy Radio Source Survey. III. Identification of a Complete Quasar Sample

Kapahi, V. K.; Athreya, R.; Subrahmanya, C. R.; Baker, Joanne; Hunstead, R. W.; McCarthy, Patrick J.; Breugel, Wil van

doi:10.1086/313145

Cited by 51 publications

(85 citation statements)

References 34 publications

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“…We note that the quasars in our sample are at slightly higher redshifts, and probably contain much steeper spectrum radio cores than the of the MRC quasars a core D 0 (Kapahi et al 1998). The radio morphology of our sources (see De Breuck et al 1998) shows much more di †use radio lobes than the more classic FR II morphologies of the MRC quasars (see Kapahi et al 1998).…”

Section: Quasarsmentioning

confidence: 67%

“…The radio morphology of our sources (see De Breuck et al 1998) shows much more di †use radio lobes than the more classic FR II morphologies of the MRC quasars (see Kapahi et al 1998). Such di †use lobes could easily be overresolved in the high-frequency radio maps used to construct our USS sample (which are of D5 times higher resolution than the low-frequency maps).…”

Section: Quasarsmentioning

confidence: 89%

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Spectroscopy of Ultra–steep-Spectrum Radio Sources

Breuck

Breugel

Röttgering

et al. 2001

The Astronomical Journal

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112

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We present optical spectroscopy of 62 objects selected from several samples of ultraÈsteep-spectrum radio sources. Forty-six of these are from our primary catalog, consisting of 669 sources with radio spectral indices a \ [1.30 this Ðrst spectroscopic subsample was selected on the basis of their faint (S l P la) ; optical and near-IR identiÐcations. Most are identiÐed as narrow-lined radio galaxies with redshifts ranging from z \ 0.25 to z \ 5.19. Ten objects are at z [ 3, nearly doubling the number of such sources known to date. Four of the USS radio sources are identiÐed with quasars, of which at least three have very red spectral energy distributions. The source TN J0936[2242 is identiÐed with an extremely red object (ERO, R[K [ 5) ; both it and a close companion are at z \ 1.479. The spectrum of the ERO closely resembles that of previously discovered radio galaxies at z D 1.5. Five sources show continuum emission, but fail to show any clear emission or absorption features, despite integrations of D1 hr with the Keck telescope. We suggest that these objects could be (1) radio galaxies with faint emission lines in the "" redshift desert ÏÏ at (2) radio galaxies with an obscured active galactic nucleus, which 1.5 [ z [ 2.3, are dominated by a stellar continuum observed with an insufficient signal-to-noise ratio, or (3) pulsars. Three radio sources identiÐed with faint objects in the K-band images remain undetected in 50È90 minute spectroscopic integrations with the Keck telescope, and are possible z [ 7 candidates.

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Section: Quasarsmentioning

confidence: 67%

Section: Quasarsmentioning

confidence: 89%

Spectroscopy of Ultra–steep-Spectrum Radio Sources

Breuck

Breugel

Röttgering

et al. 2001

The Astronomical Journal

Self Cite

112

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show abstract

“…accounting for redshift di †erences (Table 1). However the spectral index is similar for the four objects, (a 843@408 ) placing them all slightly shallow of the steep-spectrum source deÐnition (a [ 0.9) from Kapahi et al (1998). The relatively steep spectrum is typical for distant RGs (McCarthy 1993).…”

Section: Connections With the Radio Galaxymentioning

confidence: 85%

“…We have identiÐed a sample of potential high-redshift clusters from a complete sample of radio galaxies (Chapman & Kapahi et al 1998). We have selected all sources identiÐed with galaxies with measured redshifts in the range 0.8 \ z \ 1.5, using visible and images obtained K s -band with the 2.5 m du Pont Telescope at Las Campanas.…”

Section: Introductionmentioning

confidence: 99%

Radio Galaxy–selected Clusters at High Redshift and Associated Extremely Red Object Overdensities

Chapman

McCarthy

Persson

2000

The Astronomical Journal

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Galaxy clusters at high redshift present a superb opportunity to study galaxy evolution, with large galaxy samples at Ðxed distances. Several lines of evidence point toward large formation redshifts and passive evolution for cluster elliptical galaxies. At redshifts higher than z D 0.8, this picture rests on data from only a handful of rich clusters. We have observed four potential clusters to sample sparser environments in a critical redshift range, 0.8 \ z \ 1.2. We compare the photometric evolution and radial density proÐles in our clusters with more massive clusters studied in a similar manner. We also highlight the overdense extremely red object (I[K [ 5) population, signiÐcantly redder than the old elliptical population at the cluster redshift. We discuss the implications of our clusters at high redshift and possible di †erences in environment from richer clusters at similar redshifts selected through X-ray or optical techniques.

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“…For radio data, the emission from the compact emitting region is self-absorbed and the interpretation requires a more extended emission zone in which the density of particles would be low enough to prevent self-absorption (Sol et al 1989). Indeed, radio observations of PKS 0301−243 at the kilo-parsec scale exhibit an extended diffuse halo-like component resolved around a bright core (Kapahi et al 1998).…”

Section: Interpretation Of the Multi-wavelength Spectral Energy Distrmentioning

confidence: 99%

Discovery of very high energyγ-ray emission from the BL Lacertae object PKS 0301−243 with H.E.S.S.

Abramowski¹,

Acero²,

Aharonian³

et al. 2013

A&A

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The active galactic nucleus PKS 0301−243 (z = 0.266) is a high-synchrotron-peaked BL Lac object that is detected at high energies (HE, 100 MeV < E < 100 GeV) by Fermi/LAT. This paper reports on the discovery of PKS 0301−243 at very high energies (E > 100 GeV) by the High Energy Stereoscopic System (H.E.S.S.) from observations between September 2009 and December 2011 for a total live time of 34.9 h. Gamma rays above 200 GeV are detected at a significance of 9.4σ. A hint of variability at the 2.5σ level is found. An integral flux I(E > 200 GeV) = (3.3 ± 1.1 stat ± 0.7 syst ) × 10 −12 ph cm −2 s −1 and a photon index Γ = 4.6 ± 0.7 stat ± 0.2 syst are measured. Multi-wavelength light curves in HE, X-ray and optical bands show strong variability, and a minimal variability timescale of eight days is estimated from the optical light curve. A single-zone leptonic synchrotron self-Compton scenario satisfactorily reproduces the multi-wavelength data. In this model, the emitting region is out of equipartition and the jet is particle dominated. Because of its high redshift compared to other sources observed at TeV energies, the very high energy emission from PKS 0301−243 is attenuated by the extragalactic background light (EBL) and the measured spectrum is used to derive an upper limit on the opacity of the EBL.

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The Molonglo Reference Catalog 1 Jy Radio Source Survey. III. Identification of a Complete Quasar Sample

Cited by 51 publications

References 34 publications

Spectroscopy of Ultra–steep-Spectrum Radio Sources

Spectroscopy of Ultra–steep-Spectrum Radio Sources

Radio Galaxy–selected Clusters at High Redshift and Associated Extremely Red Object Overdensities

Discovery of very high energyγ-ray emission from the BL Lacertae object PKS 0301−243 with H.E.S.S.

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