The cosmic evolution of radio-AGN feedback to z=1

This paper presents the first measurement of the radio luminosity function of 'jet-mode' (radiatively-inefficient) radio-AGN out to z=1, in order to investigate the cosmic evolution of radio-AGN feedback. Eight radio source samples are combined to produce a catalogue of 211 radio-loud AGN with 0.5<z<1.0, which are spectroscopically classified into jet-mode and radiative-mode (radiatively-efficient) AGN classes. Comparing with large samples of local radio-AGN from the Sloan Digital Sky Survey, the cosmic evolution of the radio luminosity function of each radio-AGN class is independently derived. Radiative-mode radio-AGN show an order of magnitude increase in space density out to z~1 at all luminosities, consistent with these AGN being fuelled by cold gas. In contrast, the space density of jet-mode radio-AGN decreases with increasing redshift at low radio luminosities (L_1.4 < 1e24 W/Hz) but increases at higher radio luminosities. Simple models are developed to explain the observed evolution. In the best-fitting models, the characteristic space density of jet-mode AGN declines with redshift in accordance with the declining space density of massive quiescent galaxies, which fuel them via cooling of gas in their hot haloes. A time delay of 1.5-2 Gyr may be present between the quenching of star formation and the onset of jet-mode radio-AGN activity. The behaviour at higher radio luminosities can be explained either by an increasing characteristic luminosity of jet-mode radio-AGN activity with redshift (roughly as (1+z) cubed) or if the jet-mode radio-AGN population also includes some contribution of cold-gas-fuelled sources seen at a time when their accretion rate was low. Higher redshifts measurements would distinguish between these possibilities.Comment: Accepted for publication in MNRA

Setting the normalcy level of HI properties in isolated galaxies

Studying the atomic gas (HI) properties of the most isolated galaxies is essential to quantify the effect that the environment exerts on this sensitive component of the interstellar medium. We observed and compiled HI data for a well defined sample of ~ 800 galaxies in the Catalog of Isolated Galaxies, as part of the AMIGA project (Analysis of the ISM in Isolated GAlaxies, http://amiga.iaa.es), which enlarges considerably previous samples used to quantify the HI deficiency in galaxies located in denser environments. By studying the shape of 182 HI profiles, we revisited the usually accepted result that, independently of the environment, more than half of the galaxies present a perturbed HI disk. In isolated galaxies this would certainly be a striking result if these are supposed to be the most relaxed systems, and has implications in the relaxation time scales of HI disks and the nature of the most frequent perturbing mechanisms in galaxies. Our sample likely exhibits the lowest HI asymmetry level in the local Universe. We found that other field samples present an excess of ~ 20% more asymmetric HI profiles than that in CIG. Still a small percentage of galaxies in our sample present large asymmetries. Follow-up high resolution VLA maps give insight into the origin of such asymmetries.Comment: 4 pages, 2 figures, Conference 'Galaxies in Isolation: Exploring Nature vs. Nurture', Granada, 12-15 May 2009. To be published in the ASP Conference Serie

Calibration of the INCA model in a Mediterranean forested catchment: the effect of hydrological inter-annual variability in an intermittent stream

International audienceMediterranean regions are characterised by a stream hydrology with a marked seasonal pattern and high inter-annual variability. Accordingly, soil N processes and leaching of solutes in Mediterranean regions also show a marked seasonality, occurring in pulses as soils re-wet following rain. The Integrated Nitrogen Catchment model (INCA) was applied to Fuirosos, a Mediterranean catchment located in NE Spain using hydrological data and streamwater nitrate and ammonium concentrations collected from 1999 to 2002. This study tested the model under Mediterranean climate conditions and assessed the effect of the high inter-annual variability on the ability of INCA to simulate discharge and N fluxes. The model was calibrated for the whole three-year period and the n coefficients of determinion (r2) between simulated and observed data were 0.54 and 0.1 for discharge and nitrate temporal dynamics, respectively. Ammonium dynamics were simulated poorly and the linear regression between observed and simulated data was not significant statistically. To assess the effect of inter-annual variability on INCA simulations, the calibration process was run separately for two contrasting hydrological years: a dry year with a total rainfall of 525 mm and a wet year with a total of 871 mm. The coefficients of determination for the correlation between observed and simulated discharge for these two periods were 0.67 (p2 = 0.13 p2 = 0.56 p Keywords: environmental modelling, intermittent stream, Mediterranean climate, Fuirosos, hydrology, nitrat

The AMIGA sample of isolated galaxies - II. Morphological refinement

We present a complete POSS II-based refinement of the optical morphologies for galaxies in the Karatchenseva's Catalog of Isolated Galaxies that forms the basis of the AMIGA project. Comparison with independent classifications made for an SDSS overlap sample of more than 200 galaxies confirms the reliability of the early vs. late-type discrimination and the accuracy of spiral subtypes within DeltaT = 1-2. CCD images taken at the OSN were also used to solve ambiguities. 193 galaxies are flagged for the presence of nearby companions or signs of distortion likely due to interaction. This most isolated sample of galaxies in the local Universe is dominated by 2 populations: 1) 82% spirals (Sa-Sd) with the bulk being luminous systems with small bulges (63% between types Sb-Sc) and 2) a significant population of early-type E-S0 galaxies (14%). Most of the types later than Sd are low luminosity galaxies concentrated in the local supercluster where isolation is difficult to evaluate. The late-type spiral majority of the sample spans a luminosity range M_B-corr = -18 to -22 mag. Few of the E/S0 population are more luminous than -21.0 marking an absence of, an often sought, super L* merger (eg fossil elliptical) population. The rarity of high luminosity systems results in a fainter derived M* for this population compared to the spiral optical luminosity function (OLF). The E-S0 population is from 0.2 to 0.6 mag fainter depending how the sample is defined. This marks the AMIGA sample as almost unique among samples that compare early and late-type OLFs separately. In other samples, which always involve galaxies in higher density environments, M*(E/S0) is almost always 0.3-0.5 mag brighter than M*(S), presumably reflecting a stronger correlation between M* and environmental density for early-type galaxies.Comment: A&A accepted, 13 pages, 9 figures, 8 tables. Higher resolution Fig. 1 and full tables are available on the AMIGA (Analysis of the interstellar Medium of Isolated GAlaxies) website at http://www.iaa.es/AMIGA.htm

Improving keratoconus management with central corneal regularization and corneal collagen cross-linking protocol treatment

Purpose. To evaluate safety and efficacy of customized central corneal regularization (CCR), together with simultaneous accelerated corneal collagen cross-linking (A-CXL) - CCR-CXL protocol, to treat keratoconus-related corneal ectasia. Design. Retrospective, comparative observational case series. Methods. Patients that had undergone combined CCR-CXL protocol. Main inclusion criteria were keratoconus visual acuity deterioration and contact lens intolerance. All patients underwent complete ophthalmological evaluation, corrected distance visual acuity (CDVA) and Scheimpflug-corneal tomography. Central corneal regularization was performed by ablation using flying spot laser. Subsequently, the stroma was saturated with 0.17% riboflavin-5-phosphate added every 2 minutes, followed by A-CXL 9 mW/cm2 for 10 minutes. CDVA, medium keratometry value (Kmed), and total corneal morphological irregularity index (CMI) of patients were analyzed before surgery and after 1, 3 and 12 months. A P value of.05 or less was considered statistically significant. Results. 46 eyes of 39 keratoconus patients were treated. At 1 month, the mean CDVA (LogMar) increased from 0.19 ± 0.02 to 0.12 ± 0.02 (P &lt; .05), and the difference remained stable at month 12. Kmax decrease was statistically significant from 57.02 ± 5.65 to 50.21 ± 4.48 (P &lt; .05). CMI decreased significantly from 47.8 ± 2.84 to 30.1 ± 2.4 (P &lt; .01). Conclusions. CCR-CXL protocol is safe and effective in arresting keratectasia progression and increasing corneal optic regularity in keratoconus. These findings showed a significant improvement in CDVA, keratometry values and corneal optical aberrations after being treated with the CCR-CXL protocol. Copyright © Società Editrice Universo (SEU