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29 papers found.
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A survey of UV-excess AGNs in the South Galactic Pole - A sample for the analysis of the QSO clustering

Spectra, position, magnitudes and colors are presented for 485 faint () emission line objects selected with the ultraviolet-excess (UVX) criterion on a area of 24.6 deg2 in the South Galactic Pole. The objects were selected from the analysis of pixel-to-pixel stacking of COSMOS scans of UKST U J and R plates. The candidates were observed with the Meudon-ESO Fiber Optics System...

The assembly of ‘normal’ galaxies at z ∼ 7 probed by ALMA

We report new deep observations obtained with the Atacama Large Millimetre Array (ALMA) aimed at investigating the [C ii]158 μm line and continuum emission in three spectroscopically confirmed Lyman break galaxies at 6.8 < z ≤ 7.1, i.e. well within the re-ionization epoch. With star formation rates of SFR ∼ 5–15M⊙ yr− 1 these systems are much more representative of the high-z...

Faint AGNs at z > 4 in the CANDELS GOODS-S field: looking for contributors to the reionization of the Universe

Context. Establishing the number of faint active galactic nuclei (AGNs) at z = 4−6 is crucial to understanding their cosmological importance as main contributors to the reionization of the Universe.Aims. In order to derive the AGN contribution to the cosmological ionizing emissivity we have selected faint AGN candidates at z> 4 in the CANDELS GOODS-South field, which is one of...

High-resolution spectroscopy of the 3D cosmic web with close QSO groups*

We study the 3D distribution of matter at z∼ 2 using high-resolution spectra of quasi-stellar object (QSO) pairs and simulated spectra drawn from cosmological hydrodynamical simulations. We present a sample of 15 QSOs, corresponding to 21 baselines of angular separations evenly distributed between ∼1 and 14 arcmin, observed with the Ultraviolet and Visual Echelle Spectrograph...

Contamination on Lyman continuum emission at z ≳ 3: implication on the ionizing radiation evolution*

We investigate the possibility of contamination by lower redshift interlopers in the measure of the ionizing radiation escaping from high-redshift galaxies. Taking advantage of the new ultradeep Very Large Telescope/Visible Multiobject Spectrograph U-band number counts in the Great Observatories Origins Deep Survey (GOODS)-South field, we calculate the expected probability of...

Cosmic evolution of the C iv in high-resolution hydrodynamic simulations

We investigate the properties of triply ionized carbon (C iv) in the intergalactic medium (IGM) using a set of high resolution and large box size cosmological hydrodynamic simulations of a Lambda cold dark matter (ΛCDM) model. We rely on a modification of the publicly available TreeSPH code gadget-2 that self-consistently follows the metal enrichment mechanism by means of a...

The quasar proximity effect at redshift 〈z〉≃ 2.6 with the From Lines to Overdensities approach*

We revisit the proximity effect produced by quasars (QSOs) at redshifts 2.1–3.3 applying the From Lines to Overdensities (FLO) approach to a sample of ∼6300 Lyα lines fitted in 21 high resolution, high signal-to-noise spectra. This new technique allows to recover the hydrogen-density field from the H i column densities of the lines in the Lyα forest, on the basis of simple...

Tracing the gas at redshift 1.7–3.5 with the Lyα forest: the FLO approach*

We present FLO (From Lines to Overdensities), a new technique to reconstruct the hydrogen density field for the Lyα forest lines observed in high-resolution QSO spectra. The method is based on the hypothesis that the Lyα lines arise in the low to intermediate density intergalactic gas and that the Jeans length is the typical size of the Lyα absorbers. The reliability of FLO is...

High matter density peaks from UVES observations of QSO pairs: Correlation properties and chemical abundances

. , & Miralda-Escude´ , J. 1996 , ApJ, 457 , L57 Kim , T.-S., Cristiani , S. , & D'Odorico , S. 2001 , A &A, 373 , 757 de Kool , M. , Arav , N. , Becker , R. H. , et al. 2001 , ApJ, 548 , 609 Le Brun , V

The unusual N IV] -emitter galaxy GDS J033218.92-275302.7: star formation or AGN-driven winds from a massive galaxy at z = 5.56

Aims. We investigate the nature of the source GDS J033218.92-275302.7 at redshift ~5.56.Methods. The spectral energy distribution of the source is well-sampled by 16 bands photometry from UV-optical (HST and VLT), near infrared, near infrared (VLT) to mid-infrared (Spitzer). The detection of a signal in the mid-infrared Spitzer/IRAC bands 5.8, 8.0 μm – where the nebular emission...

On the radio properties of the highest redshift quasars

We present deep radio observations of the most distant complete quasar sample drawn from the Sloan Digital Sky Survey. Combining our new data with those from literature, we obtain a sample which is ∼100 per cent complete down to S1.4 GHz= 60 μJy over the redshift range 3.8 ≤z≤ 5. The fraction of radio detections is relatively high (∼43 per cent), similar to what observed locally...

Tomography of the intergalactic medium with Lyα forests in close QSO pairs*

We study the three-dimensional distribution of non-virialized matter at z∼ 2 using high-resolution spectra of quasi-stellar object (QSO) pairs and simulated spectra drawn from cosmological hydrodynamical simulations. We have collected the largest sample of QSO pairs ever observed with Ultraviolet and Visual Echelle Spectrograph (UVES) at the European Southern Observatory-Very...

Probing the evolution of the near-infrared luminosity function of galaxies to z≃ 3 in the Hubble Deep Field-South

We present the rest-frame Js- and Ks-band luminosity function (LF) of a sample of about 300 galaxies selected in the Hubble Deep Field-South (HDF-S) at Ks≤ 23 (Vega). We use calibrated photometric redshift together with spectroscopic redshift for 25 per cent of the sample. The accuracy reached in the photometric redshift estimate is 0.06 (rms) and the fraction of outliers is 1...

The power spectrum of the flux distribution in the Lyman α forest of a large sample of UVES QSO absorption spectra (LUQAS)⋆

Kaiser N. , 1987 , MNRAS, 227 , 1 Kaiser N. , Peacock J. A. , 1991 , ApJ, 379 , 482 Lomb N. R. , 1976 , Ap&SS, 39 , 447 Kim T.-S. , Cristiani , S., D'Dodorico S. , 2001 , A&A, 373 , 757 Kim T.-S

The Galaxy mass function up to z in the GOODS-MUSIC sample: into the epoch of formation of massive galaxies

Aims.The goal of this work is to measure the evolution of the Galaxy Stellar Mass Function and of the resulting Stellar Mass Density up to redshift 4, in order to study the assembly of massive galaxies in the high redshift Universe. Methods.We have used the GOODS-MUSIC catalog, containing ~3000 Ks-selected galaxies with multi-wavelength coverage extending from the U band to the...

The bright end of the z  ~ 7 UV luminosity function from a wide and deep HAWK-I survey

support from Agenzia Spaziale Italiana. Adelberger , K. L. , Steidel , C. C. , Shapley , A. E. , et al. 2004 , ApJ, 607 , 226 Arnouts, S. , D'Odorico , S. , Cristiani , S. , et al. 1999 , A &A, 341 , 641

The physical properties of the Lyα forest at z > 1.5

Combining a new, increased data set of eight quasi-stellar objects (QSOs) covering the Lyα forest at redshifts 1.5 < z < 3.6 from VLT/UVES observations with previously published results, we have investigated the properties of the Lyα forest at 1.5 < z <4. With the six QSOs covering the Lyα forest at 1.5 < z < 2.5, we have extended previous studies in this redshift range. In...

The K20 survey - VII. The spectroscopic catalogue: Spectral properties and evolution of the galaxy population

The K20 survey is a near infrared-selected, deep () redshift survey targeting galaxies in two independent regions of the sky, the Chandra Deep Field South and the field around the quasar , for a total area of 52 arcmin2. The total Ks-selected sample includes 545 objects. Low-resolution () optical spectra for 525 of them have been obtained with the FORS1/FORS2 spectrographs at the...

Measuring and modelling the redshift evolution of clustering: the Hubble Deep Field North

The evolution of galaxy clustering from z=0 to z≃4.5 is analysed using the angular correlation function and the photometric redshift distribution of galaxies brighter than IAB 28.5 in the Hubble Deep Field North. The reliability of the photometric redshift estimates is discussed on the basis of the available spectroscopic redshifts, comparing different codes and investigating the...

Photometric redshifts with the Multilayer Perceptron Neural Network: Application to the HDF-S and SDSS

size, the morphology, etc.). The target in this application is the redshift. The training has been tested on the available spectroscopic sample in the HDF−S ( Cristiani et al. 2000 ; (5) is sometimes ... Lare for her patience. Abazajian , K. , Adelman Mc Carthy , J. K. , Agüeros , M. A. , et al. 2003 , AJ, 126 , 2081 Arnouts , S. , Cristiani , S. , Moscardini , L. , et al. 1999 , MNRAS, 310 , 540 Bailer