VLA polarimetry of compact steep spectrum sources

Mantovani, F.; Junor, W.; Fanti, R.; Padrielli, L.; Saikia, D. J.

doi:10.1051/aas:1997244

Cited by 30 publications

(46 citation statements)

References 12 publications

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“…Gopal- Krishna & Wiita (1991) suggested that CSS sources would have acquired remarkable amounts of gas by galaxy interactions. Some studies support this result (e.g., Mantovani et al 1994), but several disagree with it (e.g., Fanti et al 1995;O'Dea et al 1996O'Dea et al , 2005.…”

Section: Introductionmentioning

confidence: 95%

Radio continuum spectra of gigahertz-peaked spectrum galaxies

Torniainen¹,

Tornikoski²,

Lähteenmäki³

et al. 2007

A&A

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Context. Recent studies have shown that a remarkable share of quasars classified in the literature as gigahertz-peaked spectrum (GPS) sources and high frequency peakers (HFPs) are actually flaring flat-spectrum sources or blazars. Thus, at least among the quasar-type samples, genuine GPS sources and HFPs seem to be rare. Aims. We have studied variability and the shape of the radio continuum spectra of a sample of 96 galaxy-type GPS sources and HFPs in order to find out whether there is a similar contamination in the galaxy-type samples. Methods. We collected radio data for the sample from the literature, our long-term monitoring campaigns, and recent observations, and then plotted the radio continuum spectra. We also calculated the peak frequencies, the spectral indices, and the variability indices, and finally classified the sources according to these parameters. Results. About 30% of the galaxies in our sample are clearly GPS sources, for another ∼30% there are not enough data for a solid classification, and the rest are flat-or steep-spectrum sources. Conclusions. The galaxy-type GPS samples seem to be cleaner than the quasar-type, but there is also a remarkable contamination of other source types among the galaxies. However, there may be a strong selection effect, originating from the different selection criteria of the original samples, which must be taken into consideration when comparing the results of this and our previous study. Both simultaneous spectra and long-term monitoring are essential when classifying convex-spectrum sources. However, even monitoring for several years may not reveal the variable nature of a source with a convex radio spectrum.

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Section: Introductionmentioning

confidence: 95%

Radio continuum spectra of gigahertz-peaked spectrum galaxies

Torniainen¹,

Tornikoski²,

Lähteenmäki³

et al. 2007

A&A

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“…In the south-west region, the weak and extended emission seen with the VLA observations (Mantovani et al 1990(Mantovani et al , 1997 and Fig. 1), was not detected by MERLIN.…”

Section: Merlin Observationsmentioning

confidence: 67%

“…1), was not detected by MERLIN. Mantovani et al (1997) using VLA observations measured a strong depolarization (0.52) between 8.4 GHz and 5 GHz and no indication of Faraday Rotation of the electric vector. Comparing the MERLIN image with the VLA images a similar percentage of polarized flux density is found at 5 GHz for the component A, confirming the depolarization between 8.4 GHz and 5 GHz.…”

Section: Merlin Observationsmentioning

confidence: 94%

Radio asymmetry in 3C 99

Mantovani

Fanti

Ferrari

et al. 2003

A&A

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Abstract. The N-galaxy 3C 99, a Compact Steep-spectrum Source showing a triple asymmetric structure, has been observed with several arrays of radio telescopes at sub-arcsecond resolution. New images from MERLIN, European VLBI Network and the Very Long Baseline Array show that the source components detected in the central region of 3C 99 have steep spectral indices, making it difficult to determine which of them is the core. The asymmetric radio structure of 3C 99 is explained using the Scheuer-Baldwin continuous streaming model with a rather large difference in the interstellar medium density on the two sides of the central region. The age of 3C 99 has been estimated; the source is found younger than 10 6 years.

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“…The source projected linear size is ∼3 kpc in a universe with H • = 50 km s −1 Mpc −1 and q • = 0.5. VLA observations at 5 GHz show B1524−136 to be slightly extended, while at 15 GHz it is resolved into a double source (Mantovani et al 1994). Observations with the VLBA show the northern region to have a very high rotation measure in the range of −3000 to −10000 rad m −2 in the rest frame of the source (Mantovani et al 2002).…”

Section: Introductionmentioning

confidence: 94%

Two-Sided Radio Jets in B1524–136

Mantovani

Bondì

Saikia

et al. 2003

Publ. – Astron. Soc. Aust

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Abstract:We present global VLBI and VLBA observations of the compact steep spectrum quasar B1524−136. These observations reveal well-defined radio jets on both sides of the active nucleus. Also, the overall radio structure appears highly distorted and asymmetric with the counter-jet exhibiting several oscillations. A possible scenario is one in which jet and counter-jet are inclined at about 25 • and 75 • to the line of sight respectively and an environment which is dense on the jet side. Possible implications of these results are discussed.

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VLA polarimetry of compact steep spectrum sources

Cited by 30 publications

References 12 publications

Radio continuum spectra of gigahertz-peaked spectrum galaxies

Radio continuum spectra of gigahertz-peaked spectrum galaxies

Radio asymmetry in 3C 99

Two-Sided Radio Jets in B1524–136

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