Most observational results on the high redshift restframe UVbright galaxies are based on samples pinpointed using the so-called dropout technique or Ly alpha selection. In this paper we present the ...methodology to select and study the population of high redshift galaxies in the ALHAMBRA survey data. Our aim is to develop a less biased methodology than the traditional dropout technique to study the high redshift galaxies in ALHAMBRA and other multifilter data. Thanks to the wide area ALHAMBRA covers, we especially aim at contributing to the study of the brightest, least frequent, high redshift galaxies. The methodology is based on redshift probability distribution functions (zPDFs). It is shown how a clean galaxy sample can be obtained by selecting the galaxies with high integrated probability of being within a given redshift interval. We show that using the zPDFs it is easy to select a very clean sample of high redshift galaxies.
Advanced Large Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) is photometric survey designed to trace the cosmic evolution and cosmic variance. It covers a large area of ∼4 deg2 in ...eight fields, where seven fields overlap with other surveys, allowing us to have complementary data in other wavelengths. All observations were carried out in 20 continuous, medium band (30 nm width) optical and 3 near-infrared (JHK) bands, providing the precise measurements of photometric redshifts. In addition, morphological classification of galaxies is crucial for any kind of galaxy formation and cosmic evolution studies, providing the information about star formation histories, their environment and interactions, internal perturbations, etc. We present a morphological classification of >40 000 galaxies in the ALHAMBRA survey. We associate to every galaxy a probability to be early type using the automated Bayesian code galsvm. Despite of the spatial resolution of the ALHAMBRA images (∼1 arcsec), for 22 051 galaxies, we obtained the contamination by other type of less than 10 per cent. Of those, 1640 and 10 322 galaxies are classified as early- (down to redshifts ∼0.5) and late-type (down to redshifts ∼1.0), respectively, with magnitudes F613W ≤ 22.0. In addition, for magnitude range 22.0 < F613W ≤ 23.0, we classified other 10 089 late-type galaxies with redshifts ≤1.3. We show that the classified objects populate the expected regions in the colour-mass and colour-magnitude planes. The presented data set is especially attractive given the homogeneous multiwavelength coverage available in the ALHAMBRA fields, and is intended to be used in a variety of scientific applications. The low-contamination catalogue (<10 per cent) is made publicly available with this paper.
Aims. Our aim is to determine the distribution of stellar population parameters (extinction, age, metallicity, and star formation rates) of quiescent galaxies within the rest-frame stellar ...mass–colour diagrams and UVJ colour–colour diagrams corrected for extinction up to z ∼ 1. These novel diagrams reduce the contamination in samples of quiescent galaxies owing to dust-reddened galaxies, and they provide useful constraints on stellar population parameters only using rest-frame colours and/or stellar mass. Methods. We set constraints on the stellar population parameters of quiescent galaxies combining the ALHAMBRA multi-filter photo-spectra with our fitting code for spectral energy distribution, MUlti-Filter FITting (MUFFIT), making use of composite stellar population models based on two independent sets of simple stellar population (SSP) models. The extinction obtained by MUFFIT allowed us to remove dusty star-forming (DSF) galaxies from the sample of red UVJ galaxies. The distributions of stellar population parameters across these rest-frame diagrams are revealed after the dust correction and are fitted by LOESS, a bi-dimensional and locally weighted regression method, to reduce uncertainty effects. Results. Quiescent galaxy samples defined via classical UVJ diagrams are typically contaminated by a ∼20% fraction of DSF galaxies. A significant part of the galaxies in the green valley are actually obscured star-forming galaxies (∼30–65%). Consequently, the transition of galaxies from the blue cloud to the red sequence, and hence the related mechanisms for quenching, seems to be much more efficient and faster than previously reported. The rest-frame stellar mass–colour and UVJ colour–colour diagrams are useful for constraining the age, metallicity, extinction, and star formation rate of quiescent galaxies by only their redshift, rest-frame colours, and/or stellar mass. Dust correction plays an important role in understanding how quiescent galaxies are distributed in these diagrams and is key to performing a pure selection of quiescent galaxies via intrinsic colours.
GRB 041219A is one of the longest and brightest gamma-ray bursts (GRBs) ever observed. It was discovered by the INTEGRAL satellite, and thanks to a precursor happening about 300 s before the bulk of ...the burst, ground-based telescopes were able to catch the rarely observed prompt emission in the optical and in the near-infrared bands.
Here we present the detailed analysis of its prompt gamma-ray emission, as observed with IBIS onboard INTEGRAL, and of the available X-ray afterglow data collected by X-Ray Telescope onboard Swift. We then present the late-time multiband near-infrared imaging data, collected at the Telescopio Nazionale Galileo (TNG) and the Canada-France-Hawaii Telescope (CFHT), that allowed us to identify the host galaxy of the GRB as an underluminous, irregular galaxy of ∼5 × 109 M⊙ at best-fitting redshift of z= 0.31+0.54
−0.26.
We model the broad-band prompt optical to gamma-ray emission of GRB 041219A within the internal shock model. We were able to reproduce the spectra and light curve invoking the synchrotron emission of relativistic electrons accelerated by a series of propagating shock waves inside a relativistic outflow. On the other hand, it is less easy to simultaneously reproduce the temporal and spectral properties of the infrared data.
The functional reconstruction of large neural defects usually requires the use of peripheral nerve autografts, though these have certain limitations. As a result, interest in new alternatives for ...autograft development has risen. The acellular peripheral nerve graft is an alternative for peripheral nerve injury repair, but to date there is not a standardized chemical decellularization method widely accepted. The objective of this study was to propose a modified chemical protocol of decellularization of rat sciatic nerve and its recellularization in vitro with mesenchimal differentiated Schwann-like cells. After the transplantation, an evaluation of its regeneration was performed using morphological and functional tests. The study consisted of two phases; in phase 1, different concentrations and times of exposure of rat sciatic nerves to detergents were tested, to establish a modified chemical protocol for nerve decellularization. The chemical treatment with 3% triton X-100 and 4% sodium deoxycholate for 15 days allowed a complete decellularization whilst conserving the extracellular matrix of the harvested nerve. In phase 2, the decellularized and recellularized alografts were compared against autografts. The morphological analysis showed a higher positivity to specific myelin antibodies in the recellularized group compared to the autograft. There were no differences in this parameter between the control limb and the experimental limb (recellularized group). The functional analysis showed no statistical differences at week 15 in the Sciatic Function Index in the autograft group vs the other groups. This study sets the morphological and functional bases for posterior studies about nerve defects regeneration in humans.
Dual frequency comb (DFC) spectroscopy using electro-optic comb generators stands out for its flexibility, easy implementation, and low cost. Typically, two combs with different line spacing are ...generated from a common laser using independent electro-optic comb generators. This approach minimizes the impact of laser phase noise; however, the distinct paths followed by the two combs ultimately limit the attainable signal-to-noise ratio and long-term stability of the system. In this work, a common-path DFC is generated using a single modulator driven by an arbitrary waveform generator, thus enabling a remarkable increase of the system stability (up to 0.8 s of integration time) while maintaining high flexibility. The proposed technique is experimentally validated by implementing a dual frequency comb with 3000 lines, covering an optical bandwidth of 4.5 GHz, and demonstrating an optical-to-radiofrequency compression factor of 7500. Our system is able to measure extremely narrowband optical features (in the MHz range) with an accuracy only limited by the master laser stability.
Abstract
We have identified a new Lyman limit absorption system towards PKS1937−1009, with log N(H i) = 18.25 ± 0.02 at z= 3.256 that is suitable for measuring deuterium/hydrogen (D/H). We find a ...68.3 per cent confidence range for D/H of 1.6+0.25
−0.30× 10−5 and a 95.4 per cent range of 1.6+0.5
−0.4× 10−5. The metallicity of the cloud where D/H was measured is low, Si/H=−2.0 ± 0.5. At these metallicities we expect that D/H will be close to the primordial value. Our D/H is lower than the D/H value predicted using the Ωb calculated from the cosmic background radiation measured by the Wilkinson Microwave Anisotropy Probe, 2.60+0.19
−0.17× 10−5. Our result also exacerbates the scatter in D/H values around the mean primordial D/H.
We study the clustering of galaxies as function of luminosity and redshift in the range 0.35 < z < 1.25 using data from the Advanced Large Homogeneous Area Medium-Band Redshift Astronomical ...(ALHAMBRA) survey. The ALHAMBRA data used in this work cover 2.38 deg2 in seven independent fields, after applying a detailed angular selection mask, with accurate photometric redshifts, σ
z
≲ 0.014(1 + z), down to I
AB < 24. Given the depth of the survey, we select samples in B-band luminosity down to L
th ≃ 0.16L* at z = 0.9. We measure the real-space clustering using the projected correlation function, accounting for photometric redshifts uncertainties. We infer the galaxy bias, and study its evolution with luminosity. We study the effect of sample variance, and confirm earlier results that the Cosmic Evolution Survey (COSMOS) and European Large Area ISO Survey North 1 (ELAIS-N1) fields are dominated by the presence of large structures. For the intermediate and bright samples, L
med ≳ 0.6L*, we obtain a strong dependence of bias on luminosity, in agreement with previous results at similar redshift. We are able to extend this study to fainter luminosities, where we obtain an almost flat relation, similar to that observed at low redshift. Regarding the evolution of bias with redshift, our results suggest that the different galaxy populations studied reside in haloes covering a range in mass between log10M
h/( h
−1 M⊙) ≳ 11.5 for samples with L
med ≃ 0.3L* and log10M
h/( h
−1 M⊙) ≳ 13.0 for samples with L
med ≃ 2L*, with typical occupation numbers in the range of ∼1–3 galaxies per halo.
PDF
