The VIRMOS deep imaging survey: III. ESO/WFI deep U-band imaging of the 0226-04 deep field

In this paper we describe the U-band imaging of the F02 deep field, one of the fields in the VIRMOS Deep Imaging Survey. The observations were done at the ESO/MPG 2.2m telescope at La Silla (Chile) using the 8k x 8k Wide-Field Imager (WFI). The field is centered at alpha(J2000)=02h 26m 00s and delta(J2000)=-04deg 30' 00", the total covered area is 0.9 deg**2 and the limiting magnitude (50% completeness) is U(AB) ~ 25.4 mag. Reduction steps, including astrometry, photometry and catalogue extraction, are first discussed. The achieved astrometric accuracy (RMS) is ~ 0.2" with reference to the I-band catalog and ~ 0.07" internally (estimated from overlapping sources in different exposures). The photometric accuracy including uncertainties from photometric calibration, is < 0.1 mag. Various tests are then performed as a quality assessment of the data. They include: (i) the color distribution of stars and galaxies in the field, done together with the BVRI data available from the VIMOS survey; (ii) the comparison with previous published results of U-band magnitude-number counts of galaxies.Comment: 10 pages, 13 figures, accepted for publication on Astronomy and Astrophysic

The evolution of the luminosity functions in the FORS Deep Field from low to high redshift: I. The blue bands

We use the very deep and homogeneous I-band selected dataset of the FORS Deep Field (FDF) to trace the evolution of the luminosity function over the redshift range 0.5 < z < 5.0. We show that the FDF I-band selection down to I(AB)=26.8 misses of the order of 10 % of the galaxies that would be detected in a K-band selected survey with magnitude limit K(AB)=26.3 (like FIRES). Photometric redshifts for 5558 galaxies are estimated based on the photometry in 9 filters (U, B, Gunn g, R, I, SDSS z, J, K and a special filter centered at 834 nm). A comparison with 362 spectroscopic redshifts shows that the achieved accuracy of the photometric redshifts is (Delta z / (z_spec+1)) < 0.03 with only ~ 1 % outliers. This allows us to derive luminosity functions with a reliability similar to spectroscopic surveys. In addition, the luminosity functions can be traced to objects of lower luminosity which generally are not accessible to spectroscopy. We investigate the evolution of the luminosity functions evaluated in the restframe UV (1500 Angstroem and 2800 Angstroem), u', B, and g' bands. Comparison with results from the literature shows the reliability of the derived luminosity functions. Out to redshifts of z ~ 2.5 the data are consistent with a slope of the luminosity function approximately constant with redshift, at a value of -1.07 +- 0.04 in the UV (1500 Angstroem, 2800 Angstroem) as well as u', and -1.25 +- 0.03 in the blue (g', B). We do not see evidence for a very steep slope (alpha < -1.6) in the UV at z ~ 3.0 and z ~ 4.0 favoured by other authors. There may be a tendency for the faint-end slope to become shallower with increasing redshift but the effect is marginal. We find a brightening of M_star and a decrease of Phi_star with redshift for all analyzed wavelengths. [abridged]Comment: 30 pages, re-submitted to A&A after referee comments have been taken into account, full-resolution version available at http://www.usm.uni-muenchen.de/people/gabasch/publications/gabasch_lfblue.p

The Evolution of Field Early-Type Galaxies in the FDF and WHDF

We explore the properties of 24 field early-type galaxies at 0.20<z<0.75 down to M_B<=-19.30 in a sample extracted from the FORS Deep Field and the William Herschel Deep Field. High S/N intermediate-resolution VLT spectroscopy was complemented by deep high-resolution HST/ACS imaging and additional ground-based multi-band photometry. To clarify the low level of star formation (SF) detected in some galaxies, we identify the amount of AGN activity in our sample using archive data of Chandra and XMM-Newton X-ray surveys. The B and K-band Faber-Jackson relations and the Fundamental Plane display a moderate evolution for the field early-type galaxies. Lenticular (S0) galaxies feature on average a stronger luminosity evolution and bluer rest-frame colours which can be explained that they comprise more diverse stellar populations compared to elliptical galaxies. The evolution of the FP can be interpreted as an average change in the dynamical mass-to-light ratio of our galaxies as <\Delta \log{(M/L_B)}/z>=-0.74\pm0.08. The M/L evolution of these field galaxies suggests a continuous mass assembly of field early-type galaxies during the last 5 Gyr, that gets support by recent studies of field galaxies up to z~1. Independent evidence for recent SF activity is provided by spectroscopic (OII em., Hdelta) and photometric (rest-frame colors) diagnostics. Based on the Hdelta absorption feature we detect a weak residual SF for galaxies that accounts for 5%-10% in the total stellar mass of these galaxies. The co-evolution in the luminosity and mass of our galaxies favours a downsizing formation process. We find some evidence that our galaxies experienced a period of SF quenching, possible triggered by AGN activity that is in good agreement with recent results on both observational and theoretical side. (abridged)Comment: 26 pages, 23 figures, accepted for publication in MNRA

Lyman alpha emission in high-redshift galaxies

A significant fraction of the high-redshift galaxies show strong Lyman emission lines. For redshifts z>5, most known galaxies belong to this class. However, so far not much is known about the physical structure and nature of these objects. Our aim is to analyse the Lyman alpha emission in a sample of high-redshift UV-continuum selected galaxies and to derive the physical conditions that determine the Lyman alpha profile and the line strength. VLT/FORS spectra with a resolution of R ~ 2000 of 16 galaxies in the redshift range of z = 2.7 to 5 are presented. The observed Lyman alpha profiles are compared with theoretical models. The Lyman alpha lines range from pure absorption (EW = -17 Angstroem) to strong emission (EW = 153 Angstroem). Most Lyman alpha emission lines show an asymmetric profile, and three galaxies have a double-peaked profile. Both types of profiles can be explained by a uniform model consisting of an expanding shell of neutral and ionised hydrogen around a compact starburst region. The broad, blueshifted, low-ionisation interstellar absorption lines indicate a galaxy-scale outflow of the ISM. The strengths of these lines are found to be determined in part by the velocity dispersion of the outflowing medium. We find star-formation rates of these galaxies ranging from SFR(UV) = 1.2 to 63.2 Msun uncorrected for dust absorption. The Lyman alpha emission strength of our target galaxies is found to be determined by the amount of dust and the kinematics of the outflowing material.Comment: 11 pages, 6 figures. A&A accepte

WEBT multiwavelength monitoring and XMM-Newton observations of BL Lacertae in 2007-2008. Unveiling different emission components

In 2007-2008 we carried out a new multiwavelength campaign of the Whole Earth Blazar Telescope (WEBT) on BL Lacertae, involving three pointings by the XMM-Newton satellite, to study its emission properties. The source was monitored in the optical-to-radio bands by 37 telescopes. The brightness level was relatively low. Some episodes of very fast variability were detected in the optical bands. The X-ray spectra are well fitted by a power law with photon index of about 2 and photoelectric absorption exceeding the Galactic value. However, when taking into account the presence of a molecular cloud on the line of sight, the data are best fitted by a double power law, implying a concave X-ray spectrum. The spectral energy distributions (SEDs) built with simultaneous radio-to-X-ray data at the epochs of the XMM-Newton observations suggest that the peak of the synchrotron emission lies in the near-IR band, and show a prominent UV excess, besides a slight soft-X-ray excess. A comparison with the SEDs corresponding to previous observations with X-ray satellites shows that the X-ray spectrum is extremely variable. We ascribe the UV excess to thermal emission from the accretion disc, and the other broad-band spectral features to the presence of two synchrotron components, with their related SSC emission. We fit the thermal emission with a black body law and the non-thermal components by means of a helical jet model. The fit indicates a disc temperature greater than 20000 K and a luminosity greater than 6 x 10^44 erg/s.Comment: 11 pages, 7 figures, accepted for publication in A&

Evaluating the role of paternal factors in aetiology and prognosis of recurrent pregnancy loss: Study protocol for a hospital-based multicentre case-control study and cohort study (REMI III project)

Introduction Recurrent pregnancy loss (RPL) is defined as the spontaneous demise of two or more pregnancies before the fetus reaches viability. Despite investigation of multiple known maternal risk factors, in more than 50% of couples, this condition remains unexplained. Studies focusing on paternal factors in RPL are scarce, and therefore, paternal evaluation in RPL is currently very limited. However, regarding single miscarriage, there are multiple publications suggesting a contributive role of paternal factors. In this project, we aim to identify paternal factors associated with RPL and to improve couple-specific prediction of future pregnancy outcomes by developing a prediction model containing both maternal and paternal factors. Methods and analysis In a case-control design, the relation between unexplained RPL and paternal age, lifestyle factors, sperm DNA damage and immunomodulatory factors in peripheral blood and semen will be studied. Prospectively, 135 couples with naturally conceived unexplained RPL (cases) and 135 fertile couples without a history of pregnancy loss (controls) will be included, with collection of paternal blood and semen samples and documentation of clinical and lifestyle characteristics. In addition, 600 couples from both groups will be included retrospectively. To adjust for confounders, multivariate logistic regression will be used. The predictive value of paternal and maternal factors will be studied in the total RPL cohort consisting of approximately 735 couples. The primary outcome of the cohort study is live birth within 5 years after initial visit of the clinic. Secondary outcomes are ongoing pregnancy, time interval until next pregnancy and pregnancy complications. Ethics and dissemination This project is approved by the Medical Research Ethics Committee

Generation of an ultrabroadband supercontinuum in the mid-infrared region using dispersion-engineered GeAsSe photonic crystal fiber

An ultrabroadband mid-infrared (MIR) region supercontinuum (SC) is demonstrated numerically through dispersion-engineered traditional chalcogenide (ChG) photonic crystal fiber (PCF). By varying structural parameters pitch (hole to hole spacing) and air-hole diameter to pitch ratio, a number of 10-mm-long hexagonal PCFs made employing GeAsSe ChG glass as a core and air-holes of hexagonal lattice running through their lengths as a cladding are optimized to predict an efficient mid-infrared region SC spectral emission by pumping them using a tunable pump source between 2.9 and 3.3 µm. Simulations are carried out using an ultrashort pump pulse of 100-fs duration with a low pulse peak powers of between 3 and 4 kW into the optimized designs. It is found through numerical analysis that efficient SC spectral broadening with flattened output can be obtained by increasing the PCF pitch rather than increasing the PCF cladding containing air-hole diameter although a larger nonlinear coefficient could be obtained through increasing air-hole diameter of an optimized design. Simulation results show that the SC spectra can be broadened up to 12.2 µm for a certain design with a peak power of 3 kW. Using a peak power of 4 kW, it is possible to obtain SC spectral broadening beyond 14 µm with an optimized design spanning the wavelength range from 1.8 to 14 µm which covers the electromagnetic spectrum required for MIR molecular fingerprint region applications such as sensing and biological imaging

A photometric study of faint galaxies in the field of GRB000926

We present our B, V, Rc, and Ic observations of a 3.6' x 3' field centered on the host galaxy of GRB000926 (RA(2000.0)=17h04m11s, DEC(2000.0)=+51d47'9.8''). The observations were carried out on the 6-m Special Astrophysical Observatory telescope using the SCORPIO instrument. The catalog of galaxies detected in this field includes 264 objects for which the signal-to-noise ratio is larger than 5 in each photometric band. The following limiting magnitudes in the catalog correspond to this limitation: 26.6(B), 25.7(V), 25.8(Rc), and 24.5(Ic). The differential galaxy counts are in good agreement with previously published CCD observations of deep fields. We estimated the photometric redshifts for all of the cataloged objects and studied the color variations of the galaxies with Z. For luminous spiral galaxies with M(B) < -18, we found no evidence for any noticeable evolution of their linear sizes to Z~1.Comment: 10 pages, 7 figure

3D Lyman-alpha radiation transfer. III. Constraints on gas and stellar properties of z~3 Lyman break galaxies (LBG) and implications for high-z LBGs and Lyman-alpha emitters(LAEs)

The Aim of our study is to understand the variety of observed Lyman-alpha (Lya) line profiles and strengths in Lyman Break Galaxies (LBGs) and Lya emitters (LAEs), the physical parameters governing them, and hence deriving constraints on the gas and dust content and stellar populations of these objects. Using our 3D Lya radiation transfer code including gas and dust (Verhamme et al. 2006), we fit 11 LBGs from the FORS Deep Field with redshifts between 2.8 and 5 observed by Tapken et al. (2007). A simple geometry of a spherically expanding shell of HI is adopted. RESULTS : The variety of observed Lya profiles is successfully reproduced. Most objects show outflow velocities of 150-200 km/s; two objects are most likely quasi-static. The radial HI column density ranges from NH=2.10^{19} to 7.10^{20} cm^{-2}. Our Lya profile fits yield values of E(B-V)~0.05-0.2 for the gas extinction. We find indications for a dust-to-gas ratio higher than the Galactic value, and for a substantial scatter. The escape fraction of Lya photons is found to be determined primarily by the extinction, and a simple fit formula is proposed. Intrinsic EW(Lya)~50-100 Angstroms are found for 8/11 objects, as expected for stellar populations forming constantly over long periods (> 10-100 Myr). In three cases we found indications for younger populations. Correlations between the observed EW(Lya) and other observables such as FWHM(Lya), E(B-V),SFR(UV) etc, are reproduced. We also show that there is a clear overlap between LBGs and LAEs. Radiation transfer and dust effects explain the increase of the LAE/LBG ratio, and a higher percentage of LBGs with strong Lya emission with increasing redshift. [shortened]Comment: 26 pages, accepted for publication in A&

Immune-monitoring disease activity in primary membranous nephropathy

Primary membranous nephropathy (MN) is a glomerular disease mediated by autoreactive antibodies, being the main cause of nephrotic syndrome among adult patients. While the pathogenesis of MN is still controversial, the detection of autoantibodies against two specific glomerular antigens, phospholipase A2 receptor (PLA2R) and thrombospondin type 1 domain containing 7A (THSD7A), together with the beneficial effect of therapies targeting B cells, have highlighted the main role of autoreactive B cells driving this renal disease. In fact, the detection of PLA2R-specific IgG4 antibodies has resulted in a paradigm shift regarding the diagnosis as well as a better prediction of the progression and recurrence of primary MN. Nevertheless, some patients do not show remission of the nephrotic syndrome or do rapidly recur after immunosuppression withdrawal, regardless the absence of detectable anti-PLA2R antibodies, thus highlighting the need of other immune biomarkers for MN risk-stratification. Notably, the exclusive evaluation of circulating antibodies may significantly underestimate the magnitude of the global humoral memory immune response since it may exclude the role of antigen-specific memory B cells. Therefore, the assessment of PLA2R-specific B-cell immune responses using novel technologies in a functional manner may provide novel insight on the pathogenic mechanisms of B cells triggering MN as well as refine current immune-risk stratification solely based on circulating autoantibodies