Multi-frequency study of the B3 VLA sample

Mack, K.‐H.; Vigotti, M.; Gregorini, L.; Klein, U.; Tschager, W.; Schilizzi, R. T.; Snellen, I. A. G.

doi:10.1051/0004-6361:20042621

Cited by 9 publications

(11 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It was designed to be complete down to flux densities of 100 mJy at 408 MHz. In addition to the original flux densities at 408 MHz the entire classical radio frequency range has been covered for most of the sources in the sample, both from already existent surveys (6C at 151 MHz, WENSS at 325 MHz, NVSS at 1400 MHz, GB6 at 4850 MHz) and from dedicated observations, mainly at higher frequencies (74 MHz, Mack et al 2005; 2.7 GHz, Klein et al 2003; 4.85 GHz, Vigotti et al 1999 and 10.5 GHz, Gregorini et al 1998). Based on this radio survey, Vigotti et al (1997) presented a complete sample of 125 1 quasars and this will be used as a comparison sample of radio‐loud non‐BAL quasars.…”

Section: Samples Of Bal and Non‐bal Qsos Usedmentioning

confidence: 99%

Radio spectra and polarization properties of radio-loud broad absorption-line quasars

Montenegro‐Montes

Mack

Vigotti

et al. 2008

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

We present multifrequency observations of a sample of 15 radio‐emitting broad absorption‐line quasars (BAL QSOs), covering a spectral range between 74 MHz and 43 GHz. They mostly display convex radio spectra which typically peak at about 1–5 GHz (in the observer's rest frame), flatten at MHz frequencies, probably due to synchrotron self‐absorption, and become steeper at high frequencies, i.e. ν≳ 20 GHz. Very Large Array (VLA) 22‐GHz maps (HPBW ∼80 mas) show unresolved or very compact sources, with linear projected sizes of ≤1 kpc. About two‐thirds of the sample looks unpolarized or weakly polarized at 8.4 GHz, frequency in which reasonable upper limits could be obtained for polarized intensity. Statistical comparisons have been made between the spectral index distributions of samples of BAL and non‐BAL QSOs, both in the observed and in the rest frame, finding steeper spectra among non‐BAL QSOs. However, constraining this comparison to compact sources results in no significant differences between both distributions. This comparison is consistent with BAL QSOs not being oriented along a particular line of sight. In addition, our analysis of the spectral shape, variability and polarization properties shows that radio BAL QSOs share several properties common to young radio sources like compact steep spectrum or gigahertz peaked spectrum sources.

show abstract

Section: Samples Of Bal and Non‐bal Qsos Usedmentioning

confidence: 99%

Radio spectra and polarization properties of radio-loud broad absorption-line quasars

Montenegro‐Montes

Mack

Vigotti

et al. 2008

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

show abstract

“…Therefore, the lack of fuelling in radio sources that have switched off -they are sometimes termed "faders" -should result in the absence of the hotspots as they should have faded away relatively quickly. A few objects of this kind have been observed in samples of ultra-steep spectrum sources (Röttgering et al, 1994;De Breuck et al, 2000) or as a part of very low frequency surveys (Cohen et al, 2004;Mack et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Signatures of restarted activity in core-dominated, triple radio sources selected from the FIRST survey

Marecki¹,

Thomasson

Mack

et al. 2006

A&A

Self Cite

View full text Add to dashboard Cite

Signatures of the re-occurrence of activity in radio-loud AGNs, indicated either by the so-called double-double or X-shaped structures, have been observed in a number of radio sources. All such objects known to date have linear sizes of the order of a megaparsec. A number of the sources that are appreciably more compact than this, but that exhibit hints of a past phase of activity, were found in the VLA FIRST survey. Their structures show symmetric relic lobes straddling relatively bright, unresolved cores. Observations of the cores of 15 such structures with MERLIN at 5 GHz have shown that four of them are doubles or core-jets on the subarcsecond scale. Misalignments of ∆PA > ∼ 30• between the axis of the inner structure and the line connecting the fitted maxima of the arcminute-scale relic lobes are clearly visible in three of the four sources. From these results, we can infer that a rapid repositioning of the central engine in each of these three radio sources is the most plausible interpretation of the observed morphology and that a merger is most likely the original cause of such a repositioning. In the case of TXS 1033+026, the optical image extracted from the SDSS archives clearly suggests that two objects separated by only 2.7 kpc (projected onto the sky plane) are indeed merging. The inner parts of TXS 0818+214 and TXS 1312+563 could be interpreted as double-lobed, and consequently, these sources could be of the double-double type; but further multifrequency observations are necessary to provide support for such an interpretation.

show abstract

“…It was designed to be complete down to flux densities of 100 mJy at 408 MHz. In addition to the original flux densities at 408 MHz the entire classical radio frequency range has been covered for most of the sources in the sample, both from already existent surveys (6C at 151 MHz, WENSS at 325 MHz, NVSS at 1400 MHz, GB6 at 4850 MHz) and from dedicated observations, mainly at higher frequencies (74 MHz, Mack et al 2005;2.7 GHz, Klein et al 2003;4.85 GHz, Vigotti et al 1999 and10.5 GHz, Gregorini et al 1998). Based on this radio survey, Vigotti et al (1997) presented a complete sample of 125 1 quasars and this will be used as a comparison sample of radio-loud non-BAL quasars.…”

Section: Samples Of Bal and Non-bal Qsos Usedmentioning

confidence: 99%

Radio spectra and polarisation properties of radio-loud Broad Absorption Line Quasars

Montenegro-Montes,

Mack,

Vigotti

et al. 2008

Preprint

Self Cite

View full text Add to dashboard Cite

We present multi-frequency observations of a sample of 15 radio-emitting Broad Absorption Line Quasars (BAL QSOs), covering a spectral range between 74 MHz and 43 GHz. They display mostly convex radio spectra which typically peak at about 1-5 GHz (in the observer's rest-frame), flatten at MHz frequencies, probably due to synchrotron self-absorption, and become steeper at high frequencies, i.e., ν 20 GHz. VLA 22-GHz maps (HPBW ∼ 80 mas) show unresolved or very compact sources, with linear projected sizes of 1 kpc. About 2/3 of the sample look unpolarised or weakly polarised at 8.4 GHz, frequency in which reasonable upper limits could be obtained for polarised intensity. Statistical comparisons have been made between the spectral index distributions of samples of BAL and non-BAL QSOs, both in the observed and the rest-frame, finding steeper spectra among non-BAL QSOs. However constraining this comparison to compact sources results in no significant differences between both distributions. This comparison is consistent with BAL QSOs not being oriented along a particular line of sight. In addition, our analysis of the spectral shape, variability and polarisation properties shows that radio BAL QSOs share several properties common to young radio sources like Compact Steep Spectrum (CSS) or Gigahertz-Peaked Spectrum (GPS) sources.

show abstract

Multi-frequency study of the B3 VLA sample

Cited by 9 publications

References 15 publications

Radio spectra and polarization properties of radio-loud broad absorption-line quasars

Radio spectra and polarization properties of radio-loud broad absorption-line quasars

Signatures of restarted activity in core-dominated, triple radio sources selected from the FIRST survey

Radio spectra and polarisation properties of radio-loud Broad Absorption Line Quasars

Contact Info

Product

Resources

About