Euclid preparation Bodendorf, C.; Grupp, F.; Hormuth, F. ...
Astronomy and astrophysics (Berlin),
06/2022, Letnik:
662
Journal Article
Recenzirano
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Euclid
will be the first space mission to survey most of the extragalactic sky in the 0.95–2.02 µm range, to a 5
σ
point-source median depth of 24.4 AB mag. This unique photometric dataset 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 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 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 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
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.
Upcoming surveys will map the growth of large-scale structure with unprecented precision, improving our understanding of the dark sector of the Universe. Unfortunately, much of the cosmological ...information is encoded on small scales, where the clustering of dark matter and the effects of astrophysical feedback processes are not fully understood. This can bias the estimates of cosmological parameters, which we study here for a joint analysis of mock
Euclid
cosmic shear and
Planck
cosmic microwave background data. We use different implementations for the modelling of the signal on small scales and find that they result in significantly different predictions. Moreover, the different non-linear corrections lead to biased parameter estimates, especially when the analysis is extended into the highly non-linear regime, with the Hubble constant,
H
0
, and the clustering amplitude,
σ
8
, affected the most. Improvements in the modelling of non-linear scales will therefore be needed if we are to resolve the current tension with more and better data. For a given prescription for the non-linear power spectrum, using different corrections for baryon physics does not significantly impact the precision of
Euclid
, but neglecting these correction does lead to large biases in the cosmological parameters. In order to extract precise and unbiased constraints on cosmological parameters from
Euclid
cosmic shear data, it is therefore essential to improve the accuracy of the recipes that account for non-linear structure formation, as well as the modelling of the impact of astrophysical processes that redistribute the baryons.
Background
: Pre-operative cytology in thyroid disease remains the most appropriate diagnostic test for defining the nature of a thyroid nodule before surgical excision.
Materials and methods
: We ...selected the most recent 825 surgical thyroid procedures performed in our institution from January 2004 to June 2007; 776 were total thyroidectomies, 23 were lobe-isthmectomies, and 26 were radical neck dissections. We distributed the data based on pre-operative cytology. Each cytological diagnosis was compared to results obtained by definitive histology. Tumors were called incidentalomas if they consisted of a neoplastic focus with a low grade of aggressiveness, as demonstrated by dimension <5 mm, non-aggressive histological subtype.
Results
: Of the 541 cases of benign disease, 417 were confirmed as benign. The other 124 cases are listed as follows: 29 follicular adenoma; 76 papillary carcinoma (35 found as incidentalomas), and 19 follicular carcinoma (3 incidentalomas). Cytology suggestive of papillary carcinoma was correct in 95.2% of cases (119/125). The 135 tumors termed “follicular neoplasm” were staged on pathology thus: 56 adenoma (41.4%), 26 carcinoma (19.2%), 13 (9.6%) absence of follicular proliferation, 38 (28.1%) papillary follicular variant, 2 (1.4%) undifferentiated cells. Medullary carcinomas were both confirmed. The “suspicious group” exhibited no malignancy on fine needle aspiration cytology (12 of 21; 57%).
Conclusions
: Cytology has good reliability in malignant lesions. Incidental tumors occurring in benign disease have little impact on clinical and surgical management; “follicular neoplasm” posed two problems — the impossibility of identifying the nature of the tumor, as well as the newer difficulty in distinguishing papillary follicular subtype.
BACKGROUNDPre-operative cytology in thyroid disease remains the most appropriate diagnostic test for defining the nature of a thyroid nodule before surgical excision. MATERIALS AND METHODSWe selected ...the most recent 825 surgical thyroid procedures performed in our institution from January 2004 to June 2007; 776 were total thyroidectomies, 23 were lobe-isthmectomies, and 26 were radical neck dissections. We distributed the data based on pre-operative cytology. Each cytological diagnosis was compared to results obtained by definitive histology. Tumors were called incidentalomas if they consisted of a neoplastic focus with a low grade of aggressiveness, as demonstrated by dimension <5 mm, non-aggressive histological subtype. RESULTSOf the 541 cases of benign disease, 417 were confirmed as benign. The other 124 cases are listed as follows: 29 follicular adenoma; 76 papillary carcinoma (35 found as incidentalomas), and 19 follicular carcinoma (3 incidentalomas). Cytology suggestive of papillary carcinoma was correct in 95.2% of cases (119/125). The 135 tumors termed "follicular neoplasm" were staged on pathology thus: 56 adenoma (41.4%), 26 carcinoma (19.2%), 13 (9.6%) absence of follicular proliferation, 38 (28.1%) papillary follicular variant, 2 (1.4%) undifferentiated cells. Medullary carcinomas were both confirmed. The "suspicious group" exhibited no malignancy on fine needle aspiration cytology (12 of 21; 57%). CONCLUSIONSCytology has good reliability in malignant lesions. Incidental tumors occurring in benign disease have little impact on clinical and surgical management; "follicular neoplasm" posed two problems - the impossibility of identifying the nature of the tumor, as well as the newer difficulty in distinguishing papillary follicular subtype.
Abstract This report describes the first recognized case of oncocytic mucoepidermoid carcinoma of a submandibular gland, and emphasizes the role of immunohistochemical study in the correct diagnosis ...of this tumour. This is only the second case in which this tumour has appeared as a completely cystic lesion. A review of the literature was carried out to clarify the clinical and pathological features of this rare malignancy.
Euclid preparation Aghanim, N.; Bermejo-Climent, J. R.; Paoletti, D. ...
Astronomy and astrophysics (Berlin),
01/2022, Letnik:
657
Journal Article
Recenzirano
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The combination and cross-correlation of the upcoming
Euclid
data with cosmic microwave background (CMB) measurements is a source of great expectation since it will provide the largest lever arm of ...epochs, ranging from recombination to structure formation across the entire past light cone. In this work, we present forecasts for the joint analysis of
Euclid
and CMB data on the cosmological parameters of the standard cosmological model and some of its extensions. This work expands and complements the recently published forecasts based on
Euclid
-specific probes, namely galaxy clustering, weak lensing, and their cross-correlation. With some assumptions on the specifications of current and future CMB experiments, the predicted constraints are obtained from both a standard Fisher formalism and a posterior-fitting approach based on actual CMB data. Compared to a
Euclid
-only analysis, the addition of CMB data leads to a substantial impact on constraints for all cosmological parameters of the standard Λ-cold-dark-matter model, with improvements reaching up to a factor of ten. For the parameters of extended models, which include a redshift-dependent dark energy equation of state, non-zero curvature, and a phenomenological modification of gravity, improvements can be of the order of two to three, reaching higher than ten in some cases. The results highlight the crucial importance for cosmological constraints of the combination and cross-correlation of
Euclid
probes with CMB data.
Euclid
is poised to survey galaxies across a cosmological volume of unprecedented size, providing observations of more than a billion objects distributed over a third of the full sky. Approximately ...20 million of these galaxies will have their spectroscopy available, allowing us to map the three-dimensional large-scale structure of the Universe in great detail. This paper investigates prospects for the detection of cosmic voids therein and the unique benefit they provide for cosmological studies. In particular, we study the imprints of dynamic (redshift-space) and geometric (Alcock–Paczynski) distortions of average void shapes and their constraining power on the growth of structure and cosmological distance ratios. To this end, we made use of the Flagship mock catalog, a state-of-the-art simulation of the data expected to be observed with
Euclid
. We arranged the data into four adjacent redshift bins, each of which contains about 11 000 voids and we estimated the stacked void-galaxy cross-correlation function in every bin. Fitting a linear-theory model to the data, we obtained constraints on
f
/
b
and
D
M
H
, where
f
is the linear growth rate of density fluctuations,
b
the galaxy bias,
D
M
the comoving angular diameter distance, and
H
the Hubble rate. In addition, we marginalized over two nuisance parameters included in our model to account for unknown systematic effects in the analysis. With this approach,
Euclid
will be able to reach a relative precision of about 4% on measurements of
f
/
b
and 0.5% on
D
M
H
in each redshift bin. Better modeling or calibration of the nuisance parameters may further increase this precision to 1% and 0.4%, respectively. Our results show that the exploitation of cosmic voids in
Euclid
will provide competitive constraints on cosmology even as a stand-alone probe. For example, the equation-of-state parameter,
w
, for dark energy will be measured with a precision of about 10%, consistent with previous more approximate forecasts.
Euclid preparation Desprez, G.; Coupon, J.; Almosallam, I. ...
Astronomy and astrophysics (Berlin),
12/2020, Letnik:
644
Journal Article
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Forthcoming large photometric surveys for cosmology require precise and accurate photometric redshift (photo-
z
) measurements for the success of their main science objectives. However, to date, no ...method has been able to produce photo-
z
s at the required accuracy using only the broad-band photometry that those surveys will provide. An assessment of the strengths and weaknesses of current methods is a crucial step in the eventual development of an approach to meet this challenge. We report on the performance of 13 photometric redshift code single value redshift estimates and redshift probability distributions (PDZs) on a common set of data, focusing particularly on the 0.2 − 2.6 redshift range that the
Euclid
mission will probe. We designed a challenge using emulated
Euclid
data drawn from three photometric surveys of the COSMOS field. The data was divided into two samples: one calibration sample for which photometry and redshifts were provided to the participants; and the validation sample, containing only the photometry to ensure a blinded test of the methods. Participants were invited to provide a redshift single value estimate and a PDZ for each source in the validation sample, along with a rejection flag that indicates the sources they consider unfit for use in cosmological analyses. The performance of each method was assessed through a set of informative metrics, using cross-matched spectroscopic and highly-accurate photometric redshifts as the ground truth. We show that the rejection criteria set by participants are efficient in removing strong outliers, that is to say sources for which the photo-
z
deviates by more than 0.15(1 +
z
) from the spectroscopic-redshift (spec-
z
). We also show that, while all methods are able to provide reliable single value estimates, several machine-learning methods do not manage to produce useful PDZs. We find that no machine-learning method provides good results in the regions of galaxy color-space that are sparsely populated by spectroscopic-redshifts, for example
z
> 1. However they generally perform better than template-fitting methods at low redshift (
z
< 0.7), indicating that template-fitting methods do not use all of the information contained in the photometry. We introduce metrics that quantify both photo-
z
precision and completeness of the samples (post-rejection), since both contribute to the final figure of merit of the science goals of the survey (e.g., cosmic shear from
Euclid
). Template-fitting methods provide the best results in these metrics, but we show that a combination of template-fitting results and machine-learning results with rejection criteria can outperform any individual method. On this basis, we argue that further work in identifying how to best select between machine-learning and template-fitting approaches for each individual galaxy should be pursued as a priority.
Euclid preparation Moneti, A.; Ilbert, O.; Cuby, J. ...
Astronomy and astrophysics (Berlin),
02/2022, Letnik:
658
Journal Article
Recenzirano
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We present a new infrared survey covering the three
Euclid
deep fields and four other
Euclid
calibration fields using
Spitzer
Space Telescope’s Infrared Array Camera (IRAC). We combined these new ...observations with all relevant IRAC archival data of these fields in order to produce the deepest possible mosaics of these regions. In total, these observations represent nearly 11 % of the total
Spitzer
Space Telescope mission time. The resulting mosaics cover a total of approximately 71.5 deg
2
in the 3.6 and 4.5 μm bands, and approximately 21.8 deg
2
in the 5.8 and 8 μm bands. They reach at least 24 AB magnitude (measured to 5
σ
, in a 2″.5 aperture) in the 3.6 μm band and up to ∼5 mag deeper in the deepest regions. The astrometry is tied to the
Gaia
astrometric reference system, and the typical astrometric uncertainty for sources with 16 < 3.6< 19 is ≲0″.15. The photometric calibration is in excellent agreement with previous WISE measurements. We extracted source number counts from the 3.6 μm band mosaics, and they are in excellent agreement with previous measurements. Given that the
Spitzer
Space Telescope has now been decommissioned, these mosaics are likely to be the definitive reduction of these IRAC data. This survey therefore represents an essential first step in assembling multi-wavelength data on the
Euclid
deep fields, which are set to become some of the premier fields for extragalactic astronomy in the 2020s.
Euclid preparation Gómez-Alvarez, P.; Altieri, B.; Laureijs, R. ...
Astronomy and astrophysics (Berlin),
01/2022, Letnik:
657
Journal Article
Recenzirano
Odprti dostop
Context.
While
Euclid
is an ESA mission specifically designed to investigate the nature of dark energy and dark matter, the planned unprecedented combination of survey area (∼15 000 deg
2
), spatial ...resolution, low sky-background, and depth also make
Euclid
an excellent space observatory for the study of the low surface brightness Universe. Scientific exploitation of the extended low surface brightness structures requires dedicated calibration procedures that are yet to be tested.
Aims.
We investigate the capabilities of
Euclid
to detect extended low surface brightness structure by identifying and quantifying sky-background sources and stray-light contamination. We test the feasibility of generating sky flat-fields to reduce large-scale residual gradients in order to reveal the extended emission of galaxies observed in the
Euclid
survey.
Methods.
We simulated a realistic set of
Euclid
/VIS observations, taking into account both instrumental and astronomical sources of contamination, including cosmic rays, stray-light, zodiacal light, interstellar medium, and the cosmic infrared background, while simulating the effects of background sources in the field of view.
Results.
We demonstrate that a combination of calibration lamps, sky flats, and self-calibration would enable recovery of emission at a limiting surface brightness magnitude of
μ
lim
= 29.5
−0.27
+0.08
mag arcsec
−2
(3
σ
, 10 × 10 arcsec
2
) in the Wide Survey, and it would reach regions deeper by 2 mag in the Deep Surveys.
Conclusions.Euclid
/VIS has the potential to be an excellent low surface brightness observatory. Covering the gap between pixel-to-pixel calibration lamp flats and self-calibration observations for large scales, the application of sky flat-fielding will enhance the sensitivity of the VIS detector at scales larger than 1″, up to the size of the field of view, enabling
Euclid
to detect extended surface brightness structures below
μ
lim
= 31 mag arcsec
−2
and beyond.
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