209 research outputs found
Assessing the photometric redshift precision of the S-PLUS survey : the Stripe-82 as a test-case
In this paper we present a thorough discussion about the photometric redshift (photo-z) performance of the Southern Photometric Local Universe Survey (S-PLUS). This survey combines a seven narrow +5 broad passband filter system, with a typical photometric-depth of r ∼ 21 AB. For this exercise, we utilize the Data Release 1 (DR1), corresponding to 336 deg2 from the Stripe-82 region. We rely on the BPZ2 code to compute our estimates, using a new library of SED models, which includes additional templates for quiescent galaxies. When compared to a spectroscopic redshift control sample of ∼100 k galaxies, we find a precision of σz <0.8 per cent, <2.0 per cent, or <3.0 per cent for galaxies with magnitudes r < 17, <19, and <21, respectively. A precision of 0.6 per cent is attained for galaxies with the highest Odds values. These estimates have a negligible bias and a fraction of catastrophic outliers inferior to 1 per cent. We identify a redshift window (i.e. 0.26 <z< 0.32) where our estimates double their precision, due to the simultaneous detection of two emission lines in two distinct narrow bands; representing a window opportunity to conduct statistical studies such as luminosity functions. We forecast a total of ∼2 M, ∼16 M and ∼32 M galaxies in the S-PLUS survey with a photo-z precision of σz <1.0 per cent, <2.0 per cent, and <2.5 per cent after observing 8000 deg2. We also derive redshift probability density functions, proving their reliability encoding redshift uncertainties and their potential recovering the n(z) of galaxies at z < 0.4, with an unprecedented precision for a photometric survey in the Southern hemispher
Primer registro de Rosalia alpina (Linnaeus 1758) (Coleoptera, Cerambycidae) en Prunus avium (L.) (Rosaceae)
The use of Prunus avium (L.) as habitat of the legally protected longicorn Rosalia alpina (Linnaeus, 1758) is recorded for the first time. The observations took place in a dying cherry tree located in a garden of a countryside land belonging to the municipality of Asteasu (Gipuzkoa). The presence of adults mating and looking for oviposition sites, exit holes, and one larva inside a dead branch suggest that R. alpina is able to complete its life cycle in the cherry tree. Two other saproxylic species, Cerambyx scopolii Fuessly, 1775 and Ampedus pomonae (Stephens, 1820), were found inside dead branches. In the region of the study area, R. alpina had only been previously recorded on Fagus sylvatica L. trees. Therefore, further research is suggested to determine the importance of other tree species like alternative habitat and their role in the conservation of R. alpina.El empleo de Prunus avium (L.) como hábitat para el longicornio legalmente protegido Rosalia alpina (Linnaeus, 1758) se registra por primera vez. Las observaciones tuvieron lugar en un cerezo moribundo localizado en un jardín en un entorno rural perteneciente al término municipal de Asteasu (Gipuzkoa). La presencia de adultos apareándose y buscando lugares para ovopositar, de orificios de salida y de una larva dentro de una rama muerta, sugieren que la especie es capaz de completar su ciclo biológico en el cerezo. Dentro de las ramas muertas se encontraron otras dos especies de saproxílicos: Cerambyx scopolii Fuessly, 1775 and Ampedus pomonae (Stephens, 1820). En la región del área de estudio, R. alpina sólo había sido previamente citada en ejemplares de Fagus sylvatica L. Por tanto, se recomiendan futuras investigaciones para determinar la importancia de otras especies de árboles como hábitat alternativo y su papel para la conservación de R. alpina
Photometric type Ia supernova surveys in narrow band filters
We study the characteristics of a narrow band type Ia supernova survey
through simulations based on the upcoming Javalambre Physics of the
accelerating universe Astrophysical Survey (J-PAS). This unique survey has the
capabilities of obtaining distances, redshifts, and the SN type from a single
experiment thereby circumventing the challenges faced by the resource-intensive
spectroscopic follow-up observations. We analyse the flux measurements
signal-to-noise ratio and bias, the supernova typing performance, the ability
to recover light curve parameters given by the SALT2 model, the photometric
redshift precision from type Ia supernova light curves and the effects of
systematic errors on the data. We show that such a survey is not only feasible
but may yield large type Ia supernova samples (up to 250 supernovae at
per month of search) with low core collapse contamination ( per
cent), good precision on the SALT2 parameters (average ,
and ) and on the distance modulus (average
, assuming an intrinsic scatter
), with identified systematic uncertainties
. Moreover, the
filters are narrow enough to detect most spectral features and obtain excellent
photometric redshift precision of , apart from 2 per
cent of outliers. We also present a few strategies for optimising the survey's
outcome. Together with the detailed host galaxy information, narrow band
surveys can be very valuable for the study of supernova rates, spectral feature
relations, intrinsic colour variations and correlations between supernova and
host galaxy properties, all of which are important information for supernova
cosmological applications.Comment: 20 pages, 12 tables and 26 figures. Version accepted by MNRAS, with
results slightly different from previous on
A Geometrically Supported Candidate Multiply-Imaged by the Hubble Frontier Fields Cluster Abell 2744
The deflection angles of lensed sources increase with their distance behind a
given lens. We utilize this geometric effect to corroborate the
photometric redshift estimate of a faint near-IR dropout,
triply-imaged by the massive galaxy cluster Abell 2744 in deep Hubble Frontier
Fields images. The multiple images of this source follow the same symmetry as
other nearby sets of multiple images which bracket the critical curves and have
well defined redshifts (up to ), but with larger deflection
angles, indicating that this source must lie at a higher redshift. Similarly,
our different parametric and non-parametric lens models all require this object
be at , with at least 95\% confidence, thoroughly excluding the
possibility of lower-redshift interlopers. To study the properties of this
source we correct the two brighter images for their magnifications, leading to
a SFR of /yr, a stellar mass of , and an age of Myr (95\% confidence). The intrinsic
apparent magnitude is 29.9 AB (F160W), and the rest-frame UV ()
absolute magnitude is . This corresponds to (, adopting ), making
this candidate one of the least luminous galaxies discovered at .Comment: 7 pages, 4 figures, 1 table; V2: very minor changes, ApJ Letters
Accepte
IAA : Información y actualidad astronómica (44)
Sumario : La importancia de los cometas.--
Gamow, Alpher y el ylem.--
DECONSTRUCCIÓN Y otros ENSAYOS. El universo molecular.--
EL “MOBY DICK” DE... Alberto Molino (IAG).--
CIENCIA EN HISTORIAS...Tras la estela de Plateau.--
ACTUALIDAD.--
SALA LIMPIA.--
CIENCIA: PILARES E INCERTIDUMBRES. Explosiones de rayos gamma.N
CLASH: Weak-Lensing Shear-and-Magnification Analysis of 20 Galaxy Clusters
We present a joint shear-and-magnification weak-lensing analysis of a sample
of 16 X-ray-regular and 4 high-magnification galaxy clusters at 0.19<z<0.69
selected from the Cluster Lensing And Supernova survey with Hubble (CLASH). Our
analysis uses wide-field multi-color imaging, taken primarily with Suprime-Cam
on the Subaru Telescope. From a stacked shear-only analysis of the
X-ray-selected subsample, we detect the ensemble-averaged lensing signal with a
total signal-to-noise ratio of ~25 in the radial range of 200 to 3500kpc/h. The
stacked tangential-shear signal is well described by a family of standard
density profiles predicted for dark-matter-dominated halos in gravitational
equilibrium, namely the Navarro-Frenk-White (NFW), truncated variants of NFW,
and Einasto models. For the NFW model, we measure a mean concentration of
at . We show this is in excellent agreement with Lambda
cold-dark-matter (LCDM) predictions when the CLASH X-ray selection function and
projection effects are taken into account. The best-fit Einasto shape parameter
is , which is consistent with the
NFW-equivalent Einasto parameter of . We reconstruct projected mass
density profiles of all CLASH clusters from a joint likelihood analysis of
shear-and-magnification data, and measure cluster masses at several
characteristic radii. We also derive an ensemble-averaged total projected mass
profile of the X-ray-selected subsample by stacking their individual mass
profiles. The stacked total mass profile, constrained by the
shear+magnification data, is shown to be consistent with our shear-based
halo-model predictions including the effects of surrounding large-scale
structure as a two-halo term, establishing further consistency in the context
of the LCDM model.Comment: Accepted by ApJ on 11 August 2014. Textual changes to improve clarity
(e.g., Sec.3.2.2 "Number-count Depletion", Sec.4.3 "Shape Measurement",
Sec.4.4 "Background Galaxy Selection"). Results and conclusions remain
unchanged. For the public release of Subaru data, see
http://archive.stsci.edu/prepds/clash
Phylogeography of SARS-CoV-2 pandemic in Spain: a story of multiple introductions, micro-geographic stratification, founder effects, and super-spreaders
Spain has been one of the main global pandemic epicenters for coronavirus disease 2019 (COVID-19). Here, we analyzed >41 000 genomes (including >26 000 high-quality (HQ) genomes) downloaded from the GISAID repository, including 1 245 (922 HQ) sampled in Spain. The aim of this study was to investigate genome variation of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and reconstruct phylogeographic and transmission patterns in Spain. Phylogeographic analysis suggested at least 34 independent introductions of SARS-CoV-2 to Spain at the beginning of the outbreak. Six lineages spread very successfully in the country, probably favored by super-spreaders, namely, A2a4 (7.8%), A2a5 (38.4%), A2a10 (2.8%), B3a (30.1%), and B9 (8.7%), which accounted for 87.9% of all genomes in the Spanish database. One distinct feature of the Spanish SARS-CoV-2 genomes was the higher frequency of B lineages (39.3%, mainly B3a+B9) than found in any other European country. While B3a, B9, (and an important sub-lineage of A2a5, namely, A2a5c) most likely originated in Spain, the other three haplogroups were imported from other European locations. The B3a strain may have originated in the Basque Country from a B3 ancestor of uncertain geographic origin, whereas B9 likely emerged in Madrid. The time of the most recent common ancestor (TMRCA) of SARS-CoV-2 suggested that the first coronavirus entered the country around 11 February 2020, as estimated from the TMRCA of B3a, the first lineage detected in the country. Moreover, earlier claims that the D614G mutation is associated to higher transmissibility is not consistent with the very high prevalence of COVID-19 in Spain when compared to other countries with lower disease incidence but much higher frequency of this mutation (56.4% in Spain vs. 82.4% in rest of Europe). Instead, the data support a major role of genetic drift in modeling the micro-geographic stratification of virus strains across the country as well as the role of SARS-CoV-2 super-spreaders
- …