30 GHz flux density measurements of the Caltech-Jodrell flat-spectrum sources with OCRA-p

Lowe, Stuart; Gawroński, M.; Wilkinson, P. N.; Kus, A. J.; Browne, I. W. A.; Pazderski, E.; Feiler, R.; Kettle, D.

doi:10.1051/0004-6361:20078034

Cited by 24 publications

(33 citation statements)

References 21 publications

(29 reference statements)

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“…The sample was originally created to study, among other things, the kinematics of pc-scale jets and the phenomenon of apparent superluminal motion (see Taylor et al 1996 for more details). The CJF sample (Table 1) has been most extensively studied in the radio regime (e.g., Taylor et al 1996;Pearson et al 1998;Britzen et al 1999;Vermeulen et al 2003;Pollack et al 2003;Lowe et al 2007;Britzen et al 2007b;Britzen et al 2008). Britzen et al (2008) developed a localized method for calculating the bending of the jet associated with individual components.…”

Section: Radio Emissionmentioning

confidence: 99%

Deconstructing blazars: A different scheme for jet kinematics in flat-spectrum AGN

Karouzos¹,

Britzen²,

Witzel³

et al. 2012

A&A

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Context. Recent VLBI studies of the morphology and kinematics of individual BL Lac objects (S5 1803+784, PKS 0735+178, etc.) have revealed a new paradigm for the pc-scale jet kinematics of these sources. Unlike the apparent superluminal outward motions usually observed in blazars, most, if not all, jet components in these sources appear to be stationary with respect to the core, while exhibiting strong changes in their position angles. As a result, the jet ridge lines of these sources evolve substantially, at times forming a wide channel-flow. Aims. We investigate the Caltech-Jodrell Bank flat-spectrum (CJF) sample of radio-loud active galaxies to study this new kinematic scenario for flat-spectrum AGN. Comparing BL Lac objects and quasars in the CJF, we look for differences in the kinematics and morphologies of their jet ridge lines. The large number of sources in the CJF sample, together with the excellent kinematical data available, allow us to perform a robust statistical analysis in this context. Methods. We develop a number of tools to extract information about the apparent linear and angular evolution of the CJF jet ridge lines, as well as their morphology. We study both the radial and non-radial apparent motions in the CJF jets. A statistical analysis of the extracted information allows us to test this new kinematic scenario and assess the importances of the radial and non-radial motions in flat-spectrum AGN jets in general and especially in BL Lacs compared to quasars. We also use these tools to check the kinematics for (multi-wavelength) variable AGN. Results. We find that approximately half of the sample display appreciable apparent jet widths (>10 degrees), with BL Lac jet ridge lines showing significantly larger apparent widths than those of both quasars and radio galaxies. In addition, BL Lac jet ridge lines are found to change their apparent width more strongly. Finally, BL Lac jet ridge lines show the least apparent linear evolution, which translates into the smallest apparent expansion speeds for their components. We find compelling evidence supporting a substantially different kinematic scenario for flat-spectrum radio-AGN jets and in particular for BL Lac objects. In addition, we find that variability is closely related to the properties of a source's jet ridge line. Variable quasars are found to have "BL Lac like" behavior, relative to their non-variable counterparts.

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Section: Radio Emissionmentioning

confidence: 99%

Deconstructing blazars: A different scheme for jet kinematics in flat-spectrum AGN

Karouzos¹,

Britzen²,

Witzel³

et al. 2012

A&A

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“…They were thus repeated on 2010 September 13, however, only a K-band flux calibration on J1746+6226 proved successful, for unknown reasons. The fluxes of J1746+6226 in the Ka band were extrapolated from that in the K band using a spectral index between 8.4 GHz and 30 GHz obtained from previous observations (Patnaik et al 1992;Healey et al 2007;Lowe et al 2007) listed in the NASA Extragalactic Database (NED). For J1620+4901 we made use of our observations in the off-tuned IF (selected to be centered at 37 GHz for all the Ka-band observations) to obtain the ratio of the fluxes of J1620+4901 and J1746+6226 at 37 GHz, then extrapolated the flux of J1620+4901 to the redshifted CO line frequency at 31.9 GHz using its spectral index from NED.…”

Section: Evla Observationsmentioning

confidence: 99%

THE STELLAR, MOLECULAR GAS, AND DUST CONTENT OF THE HOST GALAXIES OF TWOz∼ 2.8 DUST-OBSCURED QUASARS

Lacy

Petric

Martínez‐Sansigre

et al. 2011

The Astronomical Journal

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We present optical through radio observations of the host galaxies of two dust-obscured, luminous quasars selected in the mid-infrared, at z = 2.62 and z = 2.99, including a search for CO emission. Our limits on the CO luminosities are consistent with these objects having masses of molecular gas 10 10 M , several times less than those of luminous submillimeter-detected galaxies at comparable redshifts. Their near-infrared spectral energy distributions, however, imply that these galaxies have high stellar masses (∼10 11 -10 12 M ). The relatively small reservoirs of molecular gas and low dust masses are consistent with them being relatively mature systems at high-z.

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“…The CJF sample (Table 1) has been most extensively studied in the radio regime (e.g., Taylor et al 1996;Pearson et al 1998;Britzen et al 1999;Vermeulen et al 2003;Pollack et al 2003;Lowe et al 2007;Britzen et al 2007aBritzen et al ,b, 2008. Britzen et al (2008) develop a localized method for calculating the bending of the jet associated with individual components.…”

Section: Radio Emissionmentioning

confidence: 99%

γ-rays in flat-spectrum AGN: revisiting the fast jet hypothesis with the CJF sample

Karouzos

Britzen

Witzel

et al. 2011

A&A

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Context. The recent release of the First Fermi-LAT Source Catalog solidified the predominant association of extragalactic γ-ray emitters to active galaxies, in particular blazars. A tight connection between AGN jet kinematics and γ-ray properties has been argued for, attributing the energetic emission from active galaxies to their highly relativistic outflows. Aims. We investigate the Caltech-Jodrell Bank flat-spectrum (CJF) sample to study the connection between AGN jet kinematics and their γ-ray properties. The high number of sources included in the sample, in addition to the excellent kinematic data available, allows us to investigate the origin of γ-ray emission in AGN. Methods. We identify the CJF sources detected in γ-rays (by Fermi-LAT and EGRET). We use γ-ray luminosities and the available VLBI kinematic data to look for correlations between γ-ray and kinematic properties, as well as for differences between AGN classes (quasars, BL Lacs, radio galaxies). We also check the kinematics of the TeV sources in the CJF. Results. 21.8% of the CJF has been detected in the γ-ray regime. We find the detectability of BL Lacs significantly higher compared to quasars. Sources detected in the γ-rays show a wider apparent jet velocity distribution compared to the non-detected ones, but the maxima of both distributions are at similar values. No strong link between γ-ray detectability and fast apparent jet speeds is found. A tentative correlation is found between γ-ray luminosity and maximum apparent jet speeds, stronger for BL Lac and γ-variable sources. We find non-radial jet motions to be important to γ-ray emission. We suggest two-zone, spine-sheath models as a possible explanation for our results. Two out of four CJF TeV sources show superluminal jet speeds, in contrast to previous studies.

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30 GHz flux density measurements of the Caltech-Jodrell flat-spectrum sources with OCRA-p

Cited by 24 publications

References 21 publications

Deconstructing blazars: A different scheme for jet kinematics in flat-spectrum AGN

Deconstructing blazars: A different scheme for jet kinematics in flat-spectrum AGN

THE STELLAR, MOLECULAR GAS, AND DUST CONTENT OF THE HOST GALAXIES OF TWOz∼ 2.8 DUST-OBSCURED QUASARS

γ-rays in flat-spectrum AGN: revisiting the fast jet hypothesis with the CJF sample

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