Aims. We present new VLT ISAAC spectra for 30 quasars, which we combine with previous data to yield a sample of 53 intermediateredshift (z ≈ 0.9–3.0) sources. The sample is used to explore properties of prominent lines in the hβ spectral region of these very luminous quasars. Methods. We compare this data with two large low-redshift (z < 0.8) samples in a search for trends over almost 6dex in source luminosity. Results. We find two major trends: (1) a systematic increase in minimum FWHM hβ with luminosity (discussed in a previous paper). This lower FWHM envelope is best fit by assuming that the narrowest sources radiate near the Eddington limit, show line emission from a virialized cloud distribution, and obey a well-defined broad line region size vs. luminosity relation. (2) A systematic decrease in equivalent width of [oiii]λλ4959, 5007 (from W ≈ 15 to ∼1 A) with increasing source bolometric luminosity (from logLbol ≈ 43 to logLbol ≈ 49). Other identified trends require differntiating between so-called Population A and Bsources. We generate median composite spectra in six luminosity bins to maximize S /N. Population A sources show reasonably symmetric Lorentzian hβ profiles at all luminosities, while Pop. B sources require two component fits involving an unshifted broad and a redshifted very broad component. Very broad hβ increases in strength with increasing log Lbol, while the broad component remains constant, resulting in an apparent “Baldwin effect” with equivalent width decreasing from W ∼ 80 to ∼20 A over our sample luminosity range. The roughly constant equivalent width shown by the hβ very broad component implies production in optically-thick, photoionized gas. The onset of the redshifted very broad component appears to be a critical change that occurs near the Pop. A–B boundary at FWHM hβ ≈ 4000 km s −1 , which we relate to a critical Eddington ratio (≈0.2 ± 0.1).

/pdf/vlt-isaac-spectra-of-the-hb-region-in-intermediate-redshift-4l3le94km2.pdf

VLT/ISAAC spectra of the Hβ region in intermediate-redshift quasars III. Hβ broad-line profile analysis and inferences about BLR structure

[Abridged] We present new VLT ISAAC spectra for 30 quasars, which we combine with previous data to yield a sample of 53 intermediate redshift (z ~ 0.9 - 3.0) sources. The sample is used to explore properties of prominent lines in the Hbeta spectral region of these very luminous quasars. We find two major trends: (1) a systematic increase of minimum FWHM Hbeta with luminosity (discussed in a previous paper). This lower FWHM envelope is best fit assuming that the narrowest sources radiate near the Eddington limit, show line emission from a virialized cloud distribution, and obey a well defined broad line region size vs. luminosity relation. (2) A systematic decrease of equivalent width of [OIII] (from W ~ 15 to ~ 1 A) with increasing source bolometric luminosity (from log L ~ 43 to log L ~ 49). Further identified trends required discrimination between so-called Population A and B sources. We generate median composite spectra in six luminosity bins Pop. A sources show reasonably symmetric Lorentzian Hbeta profiles at all luminosities while Pop. B sources require two component fits involving an unshifted broad and a redshifted very broad component. Very broad Hbeta increases in strength with increasing L while the broad component remains constant resulting in an apparent "Baldwin effect" with equivalent width decreasing from W ~ 80 to ~ 20 A over our sample luminosity range. The roughly constant equivalent width shown by the Hbeta very broad component implies production in optically-thick, photoionized gas. The onset of the redshifted very broad component appears to be a critical change that occurs near the Pop. A-B boundary at FWHM Hbeta ~ 4000 km/s which we relate to a critical Eddington ratio (~ 0.2 +/- 0.1).

/pdf/vlt-isaac-spectra-of-the-hbeta-region-in-intermediate-1460i3uz2k.pdf

VLT/ISAAC Spectra of the Hbeta Region in Intermediate-Redshift Quasars III. Hbeta Broad Line Profile Analysis and Inferences about BLR Structure

We have obtained H-band spectra of 32 luminous quasars at 2.0 95%) differences between the rest-frame optical emission line properties of the BALQSO and nonBALQSO subsamples. This result is consistent with the view that all RQQs have broad-absorption-line clouds with a small (~10-20%) covering factor and that differences between the two types are merely a function of viewing angle and covering factor. (4) We report a previously unknown luminosity and/or redshift dependence of the narrow-line-region velocity width over the range 0<z<2.5, such that emission line widths increase with increasing luminosity. Furthermore, we find a ``Baldwin Effect'' for the [O III]5007 line in the RQQ-only sample over this same range in redshifts.

A Statistical Study of Rest-frame Optical Emission Properties in Luminous Quasars at 2.0 < z < 2.5

AdO, MLMA and JWS acknowledge financial support from the Spanish Ministry for Economy and Competitiveness through grants AYA2013-42227-P and AYA2016-76682-C3-1-P. MLMA, PM and MDO acknowledge funding from the INAF PRIN-SKA 2017 program 1.05.01.88.04. JP acknowledge financial support from the Spanish Ministry for Economy and Competitiveness through grants AYA2013-40609-P and AYA2016-76682-C3-3-P.

/pdf/extreme-quasars-at-high-redshift-1d9pijq22b.pdf

Extreme quasars at high redshift

We report the discovery of a z=2.83 quasar in the field of the cooling flow galaxy cluster Abell 478. This quasar was first detected in a submm survey of star forming galaxies at high redshifts, as the brightest source. We discuss the optical spectrum and far-IR spectral energy distribution (SED) of this object.

/pdf/a-submillimeter-selected-quasar-in-the-field-of-abell-478-oupryf5yle.pdf

A Submillimeter Selected Quasar in the Field of Abell 478

Infrared spectra covering the 1.6 and 2 μm regions of the quasar 1331+170, redshift z = 2.09, were obtained with CGS4 spectrometer at the UK Infrared Telescope. These spectra show redshifted Hα, Hβ, and [O III] lines. The redshifts of the forbidden lines are similar to the low-ionization line redshift. Thus the low-ionization lines are likely to provide a reliable estimate for the systematic redshift in this object, and the high-ionization material is therefore flowing out from, or into, the quasar and is subject to some obscuration

The systemic redshift of the quasar 1331 + 170

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The systemic redshift of the quasar 1331 + 170