Deep VLA observations of an optically selected sample of intermediate redshift QSOs and the optical luminosity function of the radio loud QSOs

Franca, F. La; Gregorini, L.; Cristiani, S.; Ruiter, H. de; Owen, F. N.

doi:10.1086/117176

Cited by 41 publications

(55 citation statements)

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“…This trend becomes increasingly more significant towards fainter magnitudes. Indeed, this is consistent with the observed dependence of the fraction of radio‐detected quasars as a function of optical luminosity (Padovani 1993; La Franca et al 1994; Hooper et al 1995; C03). However, Cirasuolo et al (2003b) showed that this can simply be the result of selection effects due to the radio and optical limits of the various samples, under the assumption that the optical and radio luminosities are linearly (even though) broadly correlated.…”

Section: Comparison With Previous Resultssupporting

confidence: 89%

“…In Fig. 4, we also compare our results with previous determinations of the OLF for bright ( M B ≲−25) radio‐loud quasars [La Franca et al 1994; their best‐fitting function (model B) is indicated with long‐dashed lines]. An overall good agreement between the two OLFs is found in the magnitude range in which the two samples overlap.…”

Section: Comparison With Previous Resultssupporting

confidence: 67%

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Faint radio-loud quasars: clues to their evolution

Cirasuolo

Magliocchetti

Celotti

2005

Monthly Notices of the Royal Astronomical Society

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The quasar sample selected by cross-correlating the FIRST and the 2dF Quasar Redshift Surveys allows us to explore, for the first time, the faint end of the radio and optical luminosity functions up to z = 2.2. We find indications (~3 \sigma) of a negative evolution for these faint sources at z > 1.8, both in radio and optical bands. This corresponds to a decrement in the space density of faint quasars of about a factor 2 at z=2.2 and confirms the presence of a differential evolution for the population of radio-active quasars. The faint end of both luminosity functions flattens and the comparison with the (optical) number density of the whole quasar population supports a dependence of the fraction of radio detected quasars on the optical luminosity. A progressive decrease in the fraction of quasars in the whole radio source population can be consistently accounted for within the `receding torus' scenario. The population of low luminosity quasars, which the FIRST-2dF detects, appears to depart from the `classical' scheme for radio-loud quasars.Comment: 11 pages, 7 figures, accepted for publication in MNRA

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Section: Comparison With Previous Resultssupporting

confidence: 89%

Section: Comparison With Previous Resultssupporting

confidence: 67%

Faint radio-loud quasars: clues to their evolution

Cirasuolo

Magliocchetti

Celotti

2005

Monthly Notices of the Royal Astronomical Society

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“…Simulation (b) reproduces our data qualitatively, including the BQS outliers; the quantitative differences (particularly in the BQS z distributions) are easily explained if the SSQ optical LF Z dL 408 evolves differently from the total quasar LF (e.g. La Franca et al 1994), or if the SSQ radio LF differs from that of radio galaxies (Serjeant et al, in preparation), or perhaps by unknown selection effects in the BQS itself (Goldschmidt et al 1992). The qualitative agreement was found to be robust to the assumed slope or dispersion in the radio-optical correlation.…”

Section: Simulated Radio-optical Relationssupporting

confidence: 64%

“…Several authors (e.g. La Franca et al 1994) have also noted that the total quasar population appears to have a much higher fraction of SSQs locally than at higher redshifts. One suggested explanation of this, which may also help explain the apparent incompleteness in the BQS, is that at such low redshifts the host galaxies may contribute non-negligibly to the total magnitudes.…”

Section: Simulated Radio-optical Relationsmentioning

confidence: 97%

The radio--optical correlation in steep-spectrum quasars

Serjeant

Rawlings

Maddox

et al. 1998

Monthly Notices of the Royal Astronomical Society

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A B S T R A C TUsing complete samples of steep-spectrum quasars, we present evidence for a correlation between radio and optical luminosity which is not caused by selection effects, nor caused by an orientation dependence (such as relativistic beaming), nor a by-product of cosmic evolution. We argue that this rules out models of jet formation in which there are no parameters in common with the production of the optical continuum. This is arguably the most direct evidence to date for a close link between accretion on to a black hole and the fuelling of relativistic jets. The correlation also provides a natural explanation for the presence of aligned optical/ radio structures in only the most radio-luminous high-redshift galaxies.

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“… f R = N(RL)/[N(RL) + N(RQ)], in the M B range covered by our sample. Weighting the luminosity‐dependent f R value from La Franca et al (1994) over the M B distribution of our sample (see fig. 2 of M03), i.e.…”

Section: Radio‐loud and Radio‐quiet Agnmentioning

confidence: 99%

Searching for the physical drivers of eigenvector 1: influence of black hole mass and Eddington ratio

Marziani

Zamanov

Sulentic

et al. 2003

Monthly Notices of the Royal Astronomical Society

139

257

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We compute the virial mass (M) of the central black hole and the luminosity‐to‐mass (L/M) ratio of ≈300 low‐z quasars and luminous type 1 Seyfert nuclei. We analyse the following: (1) whether radio‐quiet and radio‐loud objects show systematic differences in terms of M and L/M; (2) the influence of M and L/M on the shape of the Hβ broad component line profile; and (3) the significance of the so‐called ‘blue outliers’, i.e. sources showing a significant blueshift of the [O iii]λλ4959,5007 lines with respect to the narrow component of Hβ, which is used as an estimator of the quasar reference frame. We show that M and L/M distributions for radio‐quiet and radio‐loud sources are probably different for samples matched in luminosity and redshift, in the sense that radio‐quiet sources have systematically smaller masses and larger L/M. However, the L/M ratio distributions become indistinguishable if 8.5 < log M < 9.5. Line profile comparisons for median spectra computed over narrow ranges of M and L/M indicate that a Lorentz function provides a better fit for higher L/M sources and a double Gaussian for lower L/M values. A second (redshifted) Gaussian component at low L/M appears as a red asymmetry frequently observed in radio‐loud and radio‐quiet sources with broader (full width at half‐maximum ≳4000 km s−1) Hβ broad component profiles. This component becomes stronger in larger mass and lower L/M sources. No specific influence of radio loudness on the Hβ broad component profile is detected, although equivalent widths of Hβ broad component and especially of [O iii]λλ4959,5007 are larger for radio‐loud sources. We identify five more ‘blue outlier’ sources. Since these sources are, on average, one magnitude brighter than other active galactic nuclei with similar mass, their resulting Eddington ratio is 2–3 times higher. We hint at evolutionary effects that explain some of these results, and reinforce the ‘eigenvector 1’ correlations.

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Deep VLA observations of an optically selected sample of intermediate redshift QSOs and the optical luminosity function of the radio loud QSOs

Cited by 41 publications

References 0 publications

Faint radio-loud quasars: clues to their evolution

Faint radio-loud quasars: clues to their evolution

The radio--optical correlation in steep-spectrum quasars

Searching for the physical drivers of eigenvector 1: influence of black hole mass and Eddington ratio

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