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We aim to obtain a complete sample of redshift > 3.6 radio QSOs from FIRST sources having star-like counterparts in the SDSS DR5 photometric survey (r=3.6 QSO candidates. We obtained spectra of 27 of them, and 17 are confirmed as high-z QSOs. Spectra of 13 additional candidates from the literature and from SDSS DR6 revealed 7 more z>=3.6 QSOs, giving and overall efficiency of 60 per cent. None of the non-candidates with spectra from NED or DR6 is a z>=3.6 QSO, consistently with a high completeness. The initial sample of z>=3.6 QSOs is increased from 52 to 76, i.e. by a factor 1.46. From the new identifications and candidates we estimate an incompleteness of SDSS for the spectroscopic classification of FIRST 3.6, 16 pages, 9 figures accepted for publication in MNRAS

Are the organic molecules crucial for life on Earth abundant in early-epoch galaxies? To address this, we searched for organic molecules in extragalactic sources via their absorption features, known as diffuse interstellar bands (DIBs). There is strong evidence that DIBs are associated with polycyclic aromatic hydrocarbons (PAHs) and carbon chains. Galaxies with a preponderance of DIBs may be the most likely places in which to expect life. We use the method of quasar absorption lines to probe intervening early-epoch galaxies for the DIBs. We present the equivalent width measurements of DIBs in one neutral hydrogen (HI) abundant galaxy and limits for five DIB bands in six other HI-rich galaxies (damped Lyman-alpha systems--DLAs). Our results reveal that HI-rich galaxies are dust poor and have significantly lower reddening than known DIB-rich Milky Way environments. We find that DIBs in HI-rich galaxies do not show the same correlation with hydrogen abundance as observed in the Milky Way; the extragalactic DIBs are underabundant by as much as 10 times. The lower limit gas-to-dust ratios of four of the HI-rich early epoch galaxies are much higher than the gas-to-dust ratios found in the Milky Way. Our results suggest that the organic molecules responsible for the DIBs are underabundant in HI-rich early epoch galaxies relative to the Milky Way., Comment: 6 pages, 2 figures

We present observations of the most radio-luminous BAL quasar known, 1624+3758, at redshift z = 3.377. The quasar has several unusual properties: (1) The FeII UV191 1787-A emission line is very prominent. (2) The BAL trough (BALnicity index 2990 km/s) is detached by 21000 km/s and extends to velocity v = -29000 km/s. There are additional intrinsic absorbers at -1900 and -2800 km/s. (3) The radio rotation measure of the quasar, 18350 rad/m^2, is the second-highest known. The radio luminosity is P(1.4GHz) = 4.3 x 10^27 W/Hz (H0 = 50 km/s/Mpc, q0 = 0.5), radio loudness R* = 260. The radio source is compact (, Comment: 18 pages, 14 figures, accepted for publication in MNRAS

We define a new complete sample of 13 optically luminous radio quasars [MAB(1450ý)25.7] with redshift 3.8

Spanish astronomy has grown rapidly during the 1990s. The number of papers published per year has doubled, to about 4% of the world total. The number of high-impact papers, however, remains constant at about 1% of the world total. Papers from France, Germany and Italy also have lower impact than their numbers suggest, while for the US, UK, Japan, Netherlands and Australia, the fraction of high-impact papers is approximately the same as the fraction of all papers. We suggest a few possible explanations for this difference., Comment: 4 pages, 2 figures, proceedings of the IV scientific meeting of the Sociedad Espa\~nola de Astronoia (SEA)

We present first-season infrared (IR) and optical photometry and spectroscopy of the Type Ia Supernova 1998bu in M96. We also report optical polarimetry of this event. SN1998bu is one of the closest type Ia Supernovae of modern times and the distance of its host galaxy is well-determined. We find that SN1998bu is both photometrically and spectroscopically normal. However, the extinction to this event is unusually high, with Av=1.0 +/-0.11. We find that SN1998bu peaked at an intrinsic Mv=-19.37 +/-0.23. Adopting a distance modulus of 30.25 (Tanvir et al. 1999) and using Phillips et al.'s (1999) relations for the Hubble constant we obtain Ho=70.4 +/-4.3 km/s/Mpc. Combination of our IR photometry with those of Jha et al. (1999) provides one of the most complete early-phase IR light curves for a SN Ia published so far. In particular, SN 1998bu is the first normal SN Ia for which good pre-maximum (in the B band) IR coverage has been obtained. It reveals that the J, H and K light curves peak about 5 days earlier than the flux in the B-band curve., Comment: 22 pages, 9 figues, accepted for publication by MNRAS

For a long time, radio-loud Broad Absorption Line Quasars (BAL QSOs) were thought to be extremely rare objects. The absorbing troughs seen in their optical spectra are due to strong winds which probably have their origin within the inner region of the AGN, as a result of the accretion processes. Their radio emission constitutes an additional diagnostic tool which is successfully contributing new perspectives and raise new questions, with the aim to enrich our understanding of the BAL phenomenon. In this contribution, we introduce a first characterisation of the radio-loud BAL QSO population. Radio continuum spectra have been collected for a sample of 15 objects, which we present together with their radio polarisation properties. VLA maps in A configuration confirm the compactness of these objects at di erent frequencies up to 43 GHz, yielding projected linear sizes below 1 kpc. We note that many of their radio properties are common to the population of young radio-sources, like Compact Steep Spectrum (CSS) or Gigahertz- Peaked Spectrum (GPS) sources.

Broad Absorption Line Quasars (BAL QSOs) have been found to be associated with extremely compact radio sources. These reduced dimensions can be either due to projection effects or these objects might actually be intrinsically small. Exploring these two hypotheses is important to understand the nature and origin of the BAL phenomenon because orientation effects are an important discriminant between the different models proposed to explain this phenomenon. In this work we present VLBA observations of 5 BAL QSOs and discuss their pc-scale morphology., Comment: 6 pages, 1 table, 3 figures. To appear in Proceedings of Science: "The 9th European VLBI Symposium on The Role of VLBI in the Golden Age of Radioastronomy and EVN Users Meeting" held in Bologna (Italy) on September 23-26 2008

BAL QSOs are still a not-well understood class of objects. In the UV spectra they show Broad Absorption Lines (BALs) in the blue wings of the UV resonance lines, due to ionized gas with outflow velocities up to 0.2 c. Two different models have been proposed to explain this phenomenon: in the orientation model BAL-producing outflows should be present in all QSOs, but seen only when they intercept the observer’s line of sight. In the evolutionary model BAL QSOs are young sources still expelling their dust cocoon. We performed VLBI observations with both the EVN (4.8 GHz) and VLBA (4.8 and 8.4 GHz) to map the pc-scale structure of the brightest radio-loud objects of our sample. A variety of morphologies and orientations have been found: 5 BAL QSOs in a total of 9 observed sources have a resolved structure, with a linear size < 1 kpc. In some cases the spectral index analysis of single components suggests a beamed emission toward the observer, in other cases a symmetric structure is evident from the map. From VLBI observations BAL QSOs do not seem to have a preferred orientation. Dimensions are typical of young GPS-CSS sources. This evidence could indicate an evolutionary scenario for the origin of this class of quasars.