167 research outputs found
Evaluation of testicular echotexture with Ecotext as a diagnostic method of testicular dysfunction in stallions
This study aimed to assess if Ecotext, a new software for evaluation of testicular echotexture, is a good method for diagnosis of stallions with testicular dysfunction (TD). Relationships between Ecotext parameters and sperm motility and production, testicular volume, and testicular blood flow were also studied. Ecotext provides a total of six echotexture parameters: Ecotext 1 (black pixels), 2 (white pixels) and 3 (grey pixels), and another 3 parameters related to hypoechogenic areas: Ecotext tubular density (ETD), Ecotext tubular diameter (ETd), and Ecotext tubular area (ETA). Stallions (n = 33) were assessed using proven diagnostic techniques (spermiogram, B-mode and Pulse Doppler ultrasound), and subsequent analysis with Ecotext. Animals were classified as âcontrol stallionsâ (n:21, acceptable semen quality), and âstallions with TDâ (n:12, poor semen quality (TM < 60%, PM < 45% and total nÂș of sperm with PM < 2000 Ă 106 spz), that were subdivided into âinduced TD groupâ (immunized, anti-GnRH vaccine) and âacquired TD groupâ. The acquired TD group showed differences in all Ecotext parameters in relation to controls (Ecotext 1:0.11 ± 0.17 vs 2.82 ± 2.52, Ecotext 2:1584.0 ± 575.8 vs 388 ± 368.2, Ecotext 3:134.2 ± 9.26; ETA: 2.14 ± 0.59 vs 5.40 ± 1.90; ETd: 65.66 ± 6.27 vs 86.93 ± 10.65 and ETD: 92.35 ± 11.24 vs 132.10 ± 16.35, p †0.001). Results suggest acquired TD stallions were suffering testicular degeneration with loss of architecture and function as all Ecotext parameters were altered in relation to controls. Induced TD horses only showed a reduction in ETD (116.2 ± 8.59 vs 132.10 ± 16.35, p †0.001), despite all sperm parameters being worse. These findings suggested immunized stallions probably only experience an acute loss of testicular functionality and parenchyma architecture is likely not affected since differences in Ecotext parameters with control stallions were not detected. ETD was the best parameter to identify animals with TD (AUC: 0.84, optimal cut-off value of 124.3 seminiferous tubules/cm2). Correlations were found between ETD and Doppler indices (PI: 0.60; RI: 0.47 p †0.001), total testicular volume (r: 0.48; p †0.05) and sperm motility (TM:0.51; and PM:0.54; p †0.001) and production (r:0.51; p †0.001). In summary, Ecotext could identify changes in testicular echotexture of stallions with TD. Results open the possibility for new research focused on establishing the relationship between Ecotext parameters and histomorphometry features in stallion testes
Euclid preparation XVIII. The NISP photometric system
Euclid will be the first space mission to survey most of the extragalactic sky in the 0.95â2.02 ”m range, to a 5 Ï point-source median depth of 24.4 AB mag. This unique photometric dataset will find wide use beyond Euclidâs core science. In this paper, we present accurate computations of the Euclid YE, JE, and HE passbands used by the Near-Infrared Spectrometer and Photometer (NISP), and the associated photometric system. We pay particular attention to passband variations in the field of view, accounting for, among other factors, spatially variable filter transmission and variations in the angle of incidence on the filter substrate using optical ray tracing. The response curvesâ cut-on and cut-off wavelengths â and their variation in the field of view â are determined with âŒ0.8 nm accuracy, essential for the photometric redshift accuracy required by Euclid. After computing the photometric zero points in the AB mag system, we present linear transformations from and to common ground-based near-infrared photometric systems, for normal stars, red and brown dwarfs, and galaxies separately. A Python tool to compute accurate magnitudes for arbitrary passbands and spectral energy distributions is provided. We discuss various factors, from space weathering to material outgassing, that may slowly alter Euclidâs spectral response. At the absolute flux scale, the Euclid in-flight calibration program connects the NISP photometric system to Hubble Space Telescope spectrophotometric white dwarf standards; at the relative flux scale, the chromatic evolution of the response is tracked at the milli-mag level. In this way, we establish an accurate photometric system that is fully controlled throughout Euclidâs lifetime
Euclid preparation. XVIII. The NISP photometric system
Euclid will be the first space mission to survey most of the extragalactic
sky in the 0.95-2.02 m range, to a 5 point-source median depth of
24.4 AB mag. This unique photometric data set will find wide use beyond
Euclid's core science. In this paper, we present accurate computations of the
Euclid Y_E, J_E and H_E passbands used by the Near-Infrared Spectrometer and
Photometer (NISP), and the associated photometric system. We pay particular
attention to passband variations in the field of view, accounting among others
for spatially variable filter transmission, and variations of the angle of
incidence on the filter substrate using optical ray tracing. The response
curves' cut-on and cut-off wavelengths - and their variation in the field of
view - are determined with 0.8 nm accuracy, essential for the photometric
redshift accuracy required by Euclid. After computing the photometric
zeropoints in the AB mag system, we present linear transformations from and to
common ground-based near-infrared photometric systems, for normal stars, red
and brown dwarfs, and galaxies separately. A Python tool to compute accurate
magnitudes for arbitrary passbands and spectral energy distributions is
provided. We discuss various factors from space weathering to material
outgassing that may slowly alter Euclid's spectral response. At the absolute
flux scale, the Euclid in-flight calibration program connects the NISP
photometric system to Hubble Space Telescope spectrophotometric white dwarf
standards; at the relative flux scale, the chromatic evolution of the response
is tracked at the milli-mag level. In this way, we establish an accurate
photometric system that is fully controlled throughout Euclid's lifetime.Comment: 33 pages, 25 figures, accepted for publication in A&
Euclid preparation. TBD. Forecast impact of super-sample covariance on 3x2pt analysis with Euclid
Deviations from Gaussianity in the distribution of the fields probed by
large-scale structure surveys generate additional terms in the data covariance
matrix, increasing the uncertainties in the measurement of the cosmological
parameters. Super-sample covariance (SSC) is among the largest of these
non-Gaussian contributions, with the potential to significantly degrade
constraints on some of the parameters of the cosmological model under study --
especially for weak lensing cosmic shear. We compute and validate the impact of
SSC on the forecast uncertainties on the cosmological parameters for the Euclid
photometric survey, obtained with a Fisher matrix analysis, both considering
the Gaussian covariance alone and adding the SSC term -- computed through the
public code PySSC. The photometric probes are considered in isolation and
combined in the `32pt' analysis. We find the SSC impact to be
non-negligible -- halving the Figure of Merit of the dark energy parameters
(, ) in the 32pt case and substantially increasing the
uncertainties on , and for cosmic shear;
photometric galaxy clustering, on the other hand, is less affected due to the
lower probe response. The relative impact of SSC does not show significant
changes under variations of the redshift binning scheme, while it is smaller
for weak lensing when marginalising over the multiplicative shear bias nuisance
parameters, which also leads to poorer constraints on the cosmological
parameters. Finally, we explore how the use of prior information on the shear
and galaxy bias changes the SSC impact. Improving shear bias priors does not
have a significant impact, while galaxy bias must be calibrated to sub-percent
level to increase the Figure of Merit by the large amount needed to achieve the
value when SSC is not included.Comment: 22 pages, 13 figure
Euclid Preparation. XXVIII. Forecasts for ten different higher-order weak lensing statistics
Recent cosmic shear studies have shown that higher-order statistics (HOS)
developed by independent teams now outperform standard two-point estimators in
terms of statistical precision thanks to their sensitivity to the non-Gaussian
features of large-scale structure. The aim of the Higher-Order Weak Lensing
Statistics (HOWLS) project is to assess, compare, and combine the constraining
power of ten different HOS on a common set of -like mocks, derived from
N-body simulations. In this first paper of the HOWLS series, we computed the
nontomographic (, ) Fisher information for the
one-point probability distribution function, peak counts, Minkowski
functionals, Betti numbers, persistent homology Betti numbers and heatmap, and
scattering transform coefficients, and we compare them to the shear and
convergence two-point correlation functions in the absence of any systematic
bias. We also include forecasts for three implementations of higher-order
moments, but these cannot be robustly interpreted as the Gaussian likelihood
assumption breaks down for these statistics. Taken individually, we find that
each HOS outperforms the two-point statistics by a factor of around two in the
precision of the forecasts with some variations across statistics and
cosmological parameters. When combining all the HOS, this increases to a
times improvement, highlighting the immense potential of HOS for cosmic shear
cosmological analyses with . The data used in this analysis are
publicly released with the paper.Comment: 33 pages, 24 figures, main results in Fig. 19 & Table 5, version
published in A&
Euclid preparation. TBD. The effect of linear redshift-space distortions in photometric galaxy clustering and its cross-correlation with cosmic shear
Cosmological surveys planned for the current decade will provide us with
unparalleled observations of the distribution of galaxies on cosmic scales, by
means of which we can probe the underlying large-scale structure (LSS) of the
Universe. This will allow us to test the concordance cosmological model and its
extensions. However, precision pushes us to high levels of accuracy in the
theoretical modelling of the LSS observables, in order not to introduce biases
in the estimation of cosmological parameters. In particular, effects such as
redshift-space distortions (RSD) can become relevant in the computation of
harmonic-space power spectra even for the clustering of the photometrically
selected galaxies, as it has been previously shown in literature studies. In
this work, we investigate the contribution of linear RSD, as formulated in the
Limber approximation by arXiv:1902.07226, in forecast cosmological analyses
with the photometric galaxy sample of the Euclid survey, in order to assess
their impact and quantify the bias on the measurement of cosmological
parameters that neglecting such an effect would cause. We perform this task by
producing mock power spectra for photometric galaxy clustering and weak
lensing, as expected to be obtained from the Euclid survey. We then use a
Markov chain Monte Carlo approach to obtain the posterior distributions of
cosmological parameters from such simulated observations. We find that
neglecting the linear RSD leads to significant biases both when using galaxy
correlations alone and when these are combined with cosmic shear, in the
so-called 32pt approach. Such biases can be as large as
-equivalent when assuming an underlying CDM cosmology. When
extending the cosmological model to include the equation-of-state parameters of
dark energy, we find that the extension parameters can be shifted by more than
.Comment: 15 pages, 5 figures. To be submitted in A&
Euclid preparation: XXII. Selection of Quiescent Galaxies from Mock Photometry using Machine Learning
The Euclid Space Telescope will provide deep imaging at optical and
near-infrared wavelengths, along with slitless near-infrared spectroscopy,
across ~15,000 sq deg of the sky. Euclid is expected to detect ~12 billion
astronomical sources, facilitating new insights into cosmology, galaxy
evolution, and various other topics. To optimally exploit the expected very
large data set, there is the need to develop appropriate methods and software.
Here we present a novel machine-learning based methodology for selection of
quiescent galaxies using broad-band Euclid I_E, Y_E, J_E, H_E photometry, in
combination with multiwavelength photometry from other surveys. The ARIADNE
pipeline uses meta-learning to fuse decision-tree ensembles,
nearest-neighbours, and deep-learning methods into a single classifier that
yields significantly higher accuracy than any of the individual learning
methods separately. The pipeline has `sparsity-awareness', so that missing
photometry values are still informative for the classification. Our pipeline
derives photometric redshifts for galaxies selected as quiescent, aided by the
`pseudo-labelling' semi-supervised method. After application of the outlier
filter, our pipeline achieves a normalized mean absolute deviation of ~< 0.03
and a fraction of catastrophic outliers of ~< 0.02 when measured against the
COSMOS2015 photometric redshifts. We apply our classification pipeline to mock
galaxy photometry catalogues corresponding to three main scenarios: (i) Euclid
Deep Survey with ancillary ugriz, WISE, and radio data; (ii) Euclid Wide Survey
with ancillary ugriz, WISE, and radio data; (iii) Euclid Wide Survey only. Our
classification pipeline outperforms UVJ selection, in addition to the Euclid
I_E-Y_E, J_E-H_E and u-I_E,I_E-J_E colour-colour methods, with improvements in
completeness and the F1-score of up to a factor of 2. (Abridged)Comment: 37 pages (including appendices), 26 figures; accepted for publication
in Astronomy & Astrophysic
Euclid preparation. XXIX. Water ice in spacecraft part I: The physics of ice formation and contamination
Molecular contamination is a well-known problem in space flight. Water is the
most common contaminant and alters numerous properties of a cryogenic optical
system. Too much ice means that Euclid's calibration requirements and science
goals cannot be met. Euclid must then be thermally decontaminated, a long and
risky process. We need to understand how iced optics affect the data and when a
decontamination is required. This is essential to build adequate calibration
and survey plans, yet a comprehensive analysis in the context of an
astrophysical space survey has not been done before.
In this paper we look at other spacecraft with well-documented outgassing
records, and we review the formation of thin ice films. A mix of amorphous and
crystalline ices is expected for Euclid. Their surface topography depends on
the competing energetic needs of the substrate-water and the water-water
interfaces, and is hard to predict with current theories. We illustrate that
with scanning-tunnelling and atomic-force microscope images.
Industrial tools exist to estimate contamination, and we must understand
their uncertainties. We find considerable knowledge errors on the diffusion and
sublimation coefficients, limiting the accuracy of these tools. We developed a
water transport model to compute contamination rates in Euclid, and find
general agreement with industry estimates. Tests of the Euclid flight hardware
in space simulators did not pick up contamination signals; our in-flight
calibrations observations will be much more sensitive.
We must understand the link between the amount of ice on the optics and its
effect on Euclid's data. Little research is available about this link, possibly
because other spacecraft can decontaminate easily, quenching the need for a
deeper understanding. In our second paper we quantify the various effects of
iced optics on spectrophotometric data.Comment: 35 pages, 22 figures, A&A in press. Changes to previous version:
language edits, added Z. Bolag as author in the arxiv PDF (was listed in the
ASCII author list and in the journal PDF, but not in the arxiv PDF). This
version is identical to the journal versio
Euclid preparation: XXVI. the Euclid Morphology Challenge: Towards structural parameters for billions of galaxies
The various Euclid imaging surveys will become a reference for studies of galaxy morphology by delivering imaging over an unprecedented area of 15â000 square degrees with high spatial resolution. In order to understand the capabilities of measuring morphologies from Euclid-detected galaxies and to help implement measurements in the pipeline of the Organisational Unit MER of the Euclid Science Ground Segment, we have conducted the Euclid Morphology Challenge, which we present in two papers. While the companion paper focusses on the analysis of photometry, this paper assesses the accuracy of the parametric galaxy morphology measurements in imaging predicted from within the Euclid Wide Survey. We evaluate the performance of five state-of-the-art surface-brightness-fitting codes, DeepLeGATo, Galapagos-2, Morfometryka, ProFit and SourceXtractor++, on a sample of about 1.5 million simulated galaxies (350â000 above 5Ï) resembling reduced observations with the Euclid VIS and NIR instruments. The simulations include analytic SĂ©rsic profiles with one and two components, as well as more realistic galaxies generated with neural networks. We find that, despite some code-specific differences, all methods tend to achieve reliable structural measurements (< 10% scatter on ideal SĂ©rsic simulations) down to an apparent magnitude of about IEâ=â23 in one component and IEâ=â21 in two components, which correspond to a signal-to-noise ratio of approximately 1 and 5, respectively. We also show that when tested on non-analytic profiles, the results are typically degraded by a factor of 3, driven by systematics. We conclude that the official Euclid Data Releases will deliver robust structural parameters for at least 400 million galaxies in the Euclid Wide Survey by the end of the mission. We find that a key factor for explaining the different behaviour of the codes at the faint end is the set of adopted priors for the various structural parameters
Euclid preparation. XXV. The Euclid Morphology Challenge -- Towards model-fitting photometry for billions of galaxies
The ESA Euclid mission will provide high-quality imaging for about 1.5
billion galaxies. A software pipeline to automatically process and analyse such
a huge amount of data in real time is being developed by the Science Ground
Segment of the Euclid Consortium; this pipeline will include a model-fitting
algorithm, which will provide photometric and morphological estimates of
paramount importance for the core science goals of the mission and for legacy
science. The Euclid Morphology Challenge is a comparative investigation of the
performance of five model-fitting software packages on simulated Euclid data,
aimed at providing the baseline to identify the best suited algorithm to be
implemented in the pipeline. In this paper we describe the simulated data set,
and we discuss the photometry results. A companion paper (Euclid Collaboration:
Bretonni\`ere et al. 2022) is focused on the structural and morphological
estimates. We created mock Euclid images simulating five fields of view of 0.48
deg2 each in the band of the VIS instrument, each with three realisations
of galaxy profiles (single and double S\'ersic, and 'realistic' profiles
obtained with a neural network); for one of the fields in the double S\'ersic
realisation, we also simulated images for the three near-infrared ,
and bands of the NISP-P instrument, and five Rubin/LSST optical
complementary bands (, , , , and ). To analyse the results we
created diagnostic plots and defined ad-hoc metrics. Five model-fitting
software packages (DeepLeGATo, Galapagos-2, Morfometryka, ProFit, and
SourceXtractor++) were compared, all typically providing good results. (cut)Comment: 29 pages, 33 figures. Euclid pre-launch key paper. Companion paper:
Bretonniere et al. 202
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