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We present follow-up observations at 5, 8 and 30 GHz of the K-band Northern Wide Survey (KNoWS) 20 GHz Bright Sample, performed with the 32-m Medicina radio telescope and the 32-m Toruń radio telescope. The KNoWS sources were selected in the Northern Polar Cap (δ > 72°) and have a flux density limit S20 GHz = 115 mJy. We include NRAO-VLA Sky Survey 1.4 GHz measurements to derive the source radio spectra between 1.4 and 30 GHz. Based on optical identifications, 68 per cent of the sources are quasars and 27 per cent are radio galaxies. A redshift measurement is available for 58 per cent of the sources. The radio spectral properties of the different source populations are found to be in agreement with those of other high-frequency-selected samples.

We present VLBI observations, carried out with the European Very Long Baseline Interferometry Network (EVN), of SDSSJ143244.91+301435.3, a radio-loud narrow-line Seyfert 1 (RLNLS1) characterized by a steep radio spectrum. The source, compact at Very Large Array (VLA) resolution, is resolved on the milliarcsec scale, showing a central region plus two extended structures. The relatively high brightness temperature of all components (5x10^6-1.3x10^8 K) supports the hypothesis that the radio emission is non-thermal and likely produced by a relativistic jet and/or small radio lobes. The observed radio morphology, the lack of a significant core and the presence of a low frequency (230 MHz) spectral turnover are reminiscent of the Compact Steep Spectrum sources (CSS). However, the linear size of the source (~0.5kpc) measured from the EVN map is lower than the value predicted using the turnover/size relation valid for CSS sources (~6kpc). This discrepancy can be explained by an additional component not detected in our observations, accounting for about a quarter of the total source flux density, combined to projection effects. The low core-dominance of the source (CD, 8 pages, 3 figures, accepted for publication in MNRAS

We present SDSSJ143244.91+301435.3, a new case of radio-loud narrow line Seyfert 1 (RL NLS1) with a relatively high radio power (P1.4GHz=2.1x10^25 W Hz^-1) and large radioloudness parameter (R1.4=600+/-100). The radio source is compact with a linear size below ~1.4 kpc but, contrary to most of the RL NLS1 discovered so far with such a high R1.4, its radio spectrum is very steep (alpha=0.93) and not supporting a 'blazar-like' nature. Both the small mass of the central super-massive black-hole and the high accretion rate relative to the Eddington limit estimated for this object (3.2x10^7 Msun and 0.27, respectively, with a formal error of ~0.4 dex on both quantities) are typical of the class of NLS1. Through a modeling of the spectral energy distribution of the source we have found that the galaxy hosting SDSSJ143244.91+301435.3 is undergoing a quite intense star-formation (SFR=50 Msun y^-1) which, however, is expected to contribute only marginally (~1 per cent) to the observed radio emission. The radio properties of SDSSJ143244.91+301435.3 are remarkably similar to those of compact steep spectrum (CSS) radio sources, a class of AGN mostly composed by young radio galaxies. This may suggest a direct link between these two classes of AGN, with the CSS sources possibly representing the misaligned version (the so-called parent population) of RL NLS1 showing blazar characteristics., 14 pages, 7 figures, 4 tables, accepted for publication in MNRAS

Accounting for 20% of the total QSO population, Broad Absorption Line QSOs are still an unsolved problem in the AGN context. They present wide troughs in the UV spectrum, due to material with velocities up to 0.2 c toward the observer. The two models proposed in literature try to explain them as a particular phase of the evolution of QSOs or as normal QSOs, but seen from a particular line of sight. We built a statistically complete sample of Radio-Loud BAL QSOs, and carried out an observing campaign to piece together the whole spectrum in the cm wavelength domain, and highlight all the possible differences with respect to a comparison sample of Radio-Loud non-BAL QSOs. VLBI observations at high angular resolution have been performed, to study the pc-scale morphology of these objects. Finally, we tried to detect a possible dust component with observations at mm-wavelengths. Results do not seem to indicate a young age for all BAL QSOs. Instead a variety of orientations and morphologies have been found, constraining the outflows foreseen by the orientation model to have different possible angles with respect to the jet axis. We are grateful to the AHAR11 LOC for the economical support. Part of this work was supported by a grant of the Italian Programme for Research of Relevant National Interest (PRIN No. 18/2007, PI: K.-H. Mack) The authors acknowledge financial support from the Spanish Ministerio de Ciencia e Innovacion under project AYA2008-06311-C02-02. This work has benefited from research funding from the European Union’s sixth Framework Programme under RadioNet grant agreement no. 227290. This work has been partially based on observations with the 100-m telescope of the MPIfR (Max-PlanckInstitut f¨ur Radioastronomie) at Effelsberg. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The European VLBI Network is a joint facility of European, Chinese, South African and other radio astronomy institutes funded by their national research councils. This work has been partially based on observations carried out with the IRAM 30m single-dish. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). This publication is partially based on data acquired with the Atacama Pathfinder Experiment (APEX). APEX is a collaboration between the Max-Planck-Institut fur Radioastronomie, the European Southern Observatory, and the Onsala Space Observatory. This research has made use of the NASA/IPAC Infrared Science Archive and NASA/IPAC Extragalactic Database (NED) which are both operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Use has been made of the Sloan Digital Sky Survey (SDSS) Archive. The SDSS is managed by the Astrophysical Research Consortium (ARC) for the participating institutions: The University of Chicago, Fermilab, the Institute for Advanced Study, the Japan Participation Group, The John Hopkins University, Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-PlanckInstitute for Astrophysics (MPA), New Mexico State University, University of Pittsburgh, Princeton University, the United States Naval Observatory, and the University of Washington.

[EN]: The origin of Broad Absorption Line Quasars (BAL QSOs) is still an open issue. Accounting for ? 20% of the QSO population, these objects present broad absorption lines in their optical spectra generated from outflows with velocities up to 0.2 c. There is still no consensus about the origin of the absorbing gas in BAL QSOs, the mechanism which accelerates it, or the relationship between BAL QSOs and the quasar population as a whole. Nowadays, the hypotheses about their nature are principally related to orientation or evolutionary scenarios. In the first one, absorption lines are produced by outflows originated by the accretion disk, basically present in all QSOs, but seen only when they intercept the line of sight. In the second hypothesis, BAL QSOs would be young or recently re-fueled QSOs, still ejecting their dust cocoon. In this case orientation would not play a role, since the absorption features would be produced by spherically ejected matter. In this work we present the results of a multi-frequency study of a Radio- Loud BAL QSO sample, and a comparison sample of Radio-Loud non-BAL QSOs, both selected from the Sloan Digital Sky Survey (SDSS). We performed observations in the radio band, to sample the SED in the GHz range and study the characteristics of the synchrotron emission, aiming at collecting indications about the age and the orientation of the central radio source, as well as the polarization properties. The comparison with the non-BAL QSO sample allows us to conclude that no particular orientation is present in BAL QSOs. Nevertheless, similar fractions of GHz-peaked sources in the two sample (36±12% vs 23±8%) does not seem to suggest a young age for BAL QSOs, and this conclusion is favoured by the presence, in some cases, of low-frequency, presumably old components in the radio spectrum. Through the VLBI technique, it was possible to study the pc-scale radiomorphology of half the sample. About 80% of sources present a resolved structure, with projected linear sizes comprised between tens and hundreds of pc. This fraction is comparable with previous results from literature. The missing flux density with respect to observations at kpc-scale resolution suggests a low frequency, diffuse component in some cases. The variety of morphologies does not support a particular orientation. We also investigated the dust grey-body emission at mm-wavelengths, to verify whether BAL QSOs are dust-rich, physical condition requested by the evolutionary model. Only 7% of the sources present a clear dust contribution at 250 GHz. Not being dust rich, BAL QSOs should not present an high star-formation rate. Thus, again, they should not be a particularly young class of objects. Finally, using a sample of optically-bright Radio-Loud and Radio-Quiet QSOs, we collected spectra in the Near-Infrared band, to estimate the central black hole mass, the Eddington ratio, and the Broad Line Region radius, in order to underline dfferences induced by the Radio-Loud phase. From an analysis of the SDSS DR7 QSO catalogue, the Eddington ratio is the only physical quantity found to be significantly dfferent in Radio-Loud BAL QSOs, 26% of these objects being super-Eddington, while only 13% of Radio-Quiet BAL QSOs show the same property. Even a bigger difference has been found between BAL and non-BAL QSOs as a whole (13% vs 2%)., [ES]: El origen de los cuásares con líneas anchas de absorción (BAL QSOs, del acrónimo en inglés Broad Absorption Line Quasars) es un tema todavía en discusión. Representando aproximadamente un 20% de la población de QSOs, estos objetos muestran líneas de absorción muy anchas en su espectro óptico/UV que están generadas por flujos de material que emerge con velocidades de hasta 0.2c. No existe consenso sobre el origen de este gas causante de las absorciones, ni del mecanismo que lo acelera, o de la relación entre los cuásares BAL y el resto de la población de cuásares. Actualmente, las hipótesis sobre su naturaleza están relacionadas principalmente con la orientación o con escenarios evolutivos. En la primera, las líneas de absorción estarían producidas por flujos emergentes originados en el disco de acrecimiento asociado al agujero negro central del QSO, pero que se observarían solamente cuando interceptan la línea de visión. En un escenario evolutivo, sin embargo, los cuásares BAL serían objetos jóvenes o re-abastecidos que todavía estarían expeliendo su envoltura de gas y polvo. En este caso, la orientación no jugaría ningún papel y las absorciones estarían producidas por materia eyectada radialmente. En este trabajo se presentan los resultados de un estudio multifrecuencia de una muestra de cuásares BAL emisores en radio. Se ha seleccionado una muestra de comparación de cuásares no-BAL emisores en radio también. Ambas muestras se han seleccionado a partir del Sloan Digital Sky Survey (SDSS). Se han realizado observaciones en radio de ambas muestras, para estudiar su distribución espectral de energía (SED) en el rango del GHz y estudiar las características de la emisión sincrotrón. El objetivo es obtener estimaciones de la edad de la radiofuente, la orientación de la radiofuente central, y obtener medidas de polarización. La comparación con la muestra de objetos no-BAL nos permite concluir que no existe una orientación preferida o predominante en los cuásares BAL. Por otro lado, sin embargo, la fracción similar de fuentes con pico en 1 GHz (36±12% vs. 24±8%) no parece sugerir que los BALs sean más jóvenes. Esta conclusión está apoyada por la presencia, en algunos casos, de componentes de baja frecuencia, supuestamente viejas, en sus radio espectros. Utilizando técnicas VLBI (Very Large Baseline Interferometry) ha sido posible estudiar así mismo la morfología, a la escala del parsec, de la mitad de la muestra. Sobre un 80% de las fuentes observadas muestran estructura resuelta con tamaños proyectados de entre decenas y centenares de parsecs. Esta fracción es comparable con otros resultados de otros autores. La variedad de morfologías observada no parece apoyar la idea de orientaciones preferentes. Se investigó también en este trabajo la emisión de cuerpo gris a longitudes de onda milimétricas con el fin de determinar si los cuásares BAL pudieran ser ricos en polvo, requisito indispensable para apoyar un escenario evolutivo. Solamente un 7% de, las fuentes observadas presentan una clara contribución por polvo a 250 GHz. Al no ser ricos en polvo, los cuásares BAL no deberían presentar un alto ritmo de formación estelar, así pues, concluimos que no deben ser una clase de objetos particularmente jóvenes. Finalmente, se han estudiado dos muestras de BALs, brillantes en el rango óptico, la primera consistente en cuásares emisores en radio y la segunda, de comparación, en objetos no emisores en radio. Se obtuvieron espectros en el infrarrojo cercano para estimar la masa del agujero negro central, sus luminosidades, sus cocientes de Eddington, el tamaño de la Broad Line Region (BLR) con el fin de buscar diferencias que podrían estar inducidas en la fase de radioemisión. Después de este análisis y junto con un análisis del catálogo SDSS DR7 de cuásares, encontramos que el único parámetro que distingue a los radio cuásares BAL es el cociente de Eddington. Un 23% de los objetos emisores en radio son super-Eddington, mientras que sólo un 13% de los no emisores en radio lo son. Una diferencia aún mayor se encuentra entre cuásares BAL y no BAL (13% vs. 2%)., This thesis work has been done under the joint PhD program between the Università di Bologna and the Universidad de Cantabria.

We present new high spatial resolution Very Large Telescope (VLT) and Very Large Array (VLA) observations of a sample of nine low-power (P1.4GHz

1 Istituto di Radioastronomia del CNR, Via P. Gobetti 101, I-40129 Bologna, Italy 2 Radioastronomisches Institut der Universitat Bonn, Auf dem Hugel 71, D-53121 Bonn, Germany 3 Sterrewacht Leiden, PO Box 9513, NL-2300 RA Leiden, The Netherlands 4 Int. SKA Project Office, Postbus 2, NL-7990 AA Dwingeloo, The Netherlands 5 Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, United Kingdom