430 research outputs found
Trident: A three-pronged galaxy survey. I. Lyman alpha emitting galaxies at z~2 in GOODS North
Context. Lyman alpha emitting galaxies (LAEs) are used to probe the distant
universe and are therefore important for galaxy evolution studies and for
providing clues to the nature of the epoch of reionization, but the exact
circumstances under which Lyman alpha escapes a galaxy are still not fully
understood.
Aims. The Trident project is designed to simultaneously examine Lyman alpha,
H-alpha and Lyman Continuum emission from galaxies at redshift z~2, thus
linking together these three aspects of ionising radiation in galaxies. In this
paper, we outline the strategy of this project and examine the properties of
LAEs in the GOODS North field.
Methods. We performed a narrowband LAE survey in GOODS North using existing
and two custom made filters at the Nordic Optical Telescope with MOSCA. We use
complementary broad band archival data in the field to make a careful candidate
selection and perform optical to near-IR SED fitting. We also estimate
far-infrared luminosities by matching our candidates to detections in
Spitzer/MIPS 24{\mu}m and Herschel/PACS catalogs.
Results. We find a total of 25 LAE candidates, probing mainly the bright end
of the LAE luminosity function with L_Ly {\alpha} ~ 1-15e42 erg/s. They display
a range of masses of ~0.5-50e9 M_solar, and average ages from a few tens of Myr
to 1 Gyr when assuming a constant star formation history. The majority of our
candidates also show signs of recent elevated star formation. Three candidates
have counterparts in the GOODS-Herschel far-IR catalogue, with luminosities
consistent with ultra-luminous infrared galaxies (ULIRGs).
Conclusions. The wide range of parameters derived from our SED fitting, as
well as part of our sample being detected as ULIRGs, seems to indicate that at
these Lyman alpha luminosities, LAEs do not necessarily have to be young
dwarfs, and that a lack of dust is not required for Lyman alpha to escape.Comment: 16 pages, 12 figures. Accepted version for publication in A&
Estimulación motora en niños con déficit visual: plan de actividades para alumnos de 1º de Primaria
A partir de la experiencia realizada con un niño con baja visión, escolarizado en 1.º de Primaria, la autora plantea una propuesta de intervención, con la finalidad de demostrar que la práctica psicomotriz es necesaria, entre los 4 y los 6 años de edad, en niños con deficiencia visual. El objetivo fundamental es mejorar el entorno social y educativo de los alumnos, a través del aprendizaje motor. El programa se aplica a lo largo del curso escolar, conjuntamente con la asignatura de Educación Física. El plan de actividades trata de lograr la estimulación motora mediante tareas de lateralidad, conocimiento del propio cuerpo, equilibrio, autonomía en la vida diaria, higiene postural y juegos de expresión
Peering through the holes: the far UV color of star-forming galaxies at z~3-4 and the escaping fraction of ionizing radiation
We aim to investigate the effect of the escaping ionizing radiation on the
color selection of high redshift galaxies and identify candidate Lyman
continuum (LyC) emitters. The intergalactic medium prescription of Inoue et
al.(2014) and galaxy synthesis models of Bruzual&Charlot (2003) have been used
to properly treat the ultraviolet stellar emission, the stochasticity of the
intergalactic transmission and mean free path in the ionizing regime. Color
tracks are computed by turning on/off the escape fraction of ionizing
radiation. At variance with recent studies, a careful treatment of IGM
transmission leads to no significant effects on the high-redshift broad-band
color selection. The decreasing mean free path of ionizing photons with
increasing redshift further diminishes the contribution of the LyC to
broad-band colors. We also demonstrate that prominent LyC sources can be
selected under suitable conditions by calculating the probability of a null
escaping ionizing radiation. The method is applied to a sample of galaxies
extracted from the GOODS-S field. A known LyC source at z=3.795 is successfully
recovered as a LyC emitter candidate and another convincing candidate at
z=3.212 is reported. A detailed analysis of the two sources (including their
variability and morphology) suggests a possible mixture of stellar and
non-stellar (AGN) contribution in the ultraviolet. Conclusions: Classical
broad-band color selection of 2.5<z<4.5 galaxies does not prevent the inclusion
of LyC emitters in the selected samples. Large fesc in relatively bright
galaxies (L>0.1L*) could be favored by the presence of a faint AGN not easily
detected at any wavelength. A hybrid stellar and non-stellar (AGN) ionizing
emission could coexist in these systems and explain the tensions found among
the UV excess and the stellar population synthesis models reported in
literature.Comment: Accepted for publication in Astronomy & Astrophysics. 13 pages, 7
figure
Use of polyaspartates for the tartaric stabilisation of white and red wines and side effects on wine characteristics
Aim: The stabilising efficacy against tartaric precipitations of polyaspartates-based products (PAs), in particular potassium polyaspartate (KPA), was tested with six different wines (three white and three red). Some side effects on wine characteristics (white wine colour stability, wine turbidity and filterability) were also studied.
Results and conclusions: All PAs showed good stabilising efficacy against tartaric precipitations according to the cold test. With the same test, the PAs were stable in wine for 1 year of storage, which was the total duration of the study. The dose of 100 mg/L was sufficient to stabilise the tested wines. No differences in filterability were observed in comparison with MTA (metatartaric acid). The hypothesised protective effect against colour browning in white wines was not observed. Significance and impact of the study: The international wine trade requires stable wines. This paper provides information to support wineries in managing the use of KPA, as little information is available to date in the literature on this stabilising additive
Constraining Lyman-alpha spatial offsets at from VANDELS slit spectroscopy
We constrain the distribution of spatially offset Lyman-alpha emission
(Ly) relative to rest-frame ultraviolet emission in high
redshift () Lyman-break galaxies (LBGs) exhibiting Ly emission
from VANDELS, a VLT/VIMOS slit-spectroscopic survey of the CANDELS Ultra Deep
Survey and Chandra Deep Field South fields (
total). Because slit spectroscopy compresses two-dimensional spatial
information into one spatial dimension, we use Bayesian inference to recover
the underlying Ly spatial offset distribution. We model the
distribution using a 2D circular Gaussian, defined by a single parameter
, the standard deviation expressed in polar
coordinates. Over the entire redshift range of our sample (), we find
kpc ( conf.),
corresponding to arcsec at . We also find that
decreases significantly with redshift. Because
Ly spatial offsets can cause slit-losses, the decrease in
with redshift can partially explain the increase
in the fraction of Ly emitters observed in the literature over this
same interval, although uncertainties are still too large to reach a strong
conclusion. If continues to decrease into the
reionization epoch, then the decrease in Ly transmission from galaxies
observed during this epoch might require an even higher neutral hydrogen
fraction than what is currently inferred. Conversely, if spatial offsets
increase with the increasing opacity of the IGM, slit losses may explain some
of the drop in Ly transmission observed at . Spatially resolved
observations of Ly and UV continuum at are needed to settle the
issue.Comment: Submitted to MNRA
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