Abstract
The Physics of the Accelerating Universe Survey (PAUS) is an innovative photometric survey with 40 narrow-bands at the William Herschel Telescope (WHT). The narrow-bands are spaced at 100 Å ...intervals covering the range 4500–8500 Å and, in combination with standard broad-bands, enable excellent redshift precision. This paper describes the technique, galaxy templates, and additional photometric calibration used to determine early photometric redshifts from PAUS. Using bcnz2, a new photometric redshift code developed for this purpose, we characterize the photometric redshift performance using PAUS data on the COSMOS field. Comparison to secure spectra from zCOSMOS DR3 shows that PAUS achieves σ68/(1 + $z$) = 0.0037 to iAB < 22.5 for the redshift range 0 < $z$ < 1.2, when selecting the best 50 per cent of the sources based on a photometric redshift quality cut. Furthermore, a higher photo-z precision σ68/(1 + $z$) ∼ 0.001 is obtained for a bright and high-quality selection, which is driven by the identification of emission lines. We conclude that PAUS meets its design goals, opening up a hitherto uncharted regime of deep, wide, and dense galaxy survey with precise redshifts that will provide unique insights into the formation, evolution, and clustering of galaxies, as well as their intrinsic alignments.
ABSTRACT The physics of the accelerating Universe (PAU) camera is an optical narrow band and broad band imaging instrument mounted at the prime focus of the William Herschel Telescope. We describe ...the image calibration procedure of the PAU survey data. We rely on an external photometric catalogue to calibrate our narrow band data using stars that have been observed by both data sets. We fit stellar templates to the stellar broad-band photometry of the Sloan Digital Sky Survey and synthesize narrow band photometry that we compare to the PAUS narrow band data to determine their calibration. Consequently, the PAUS data are in the AB system as inherited from its reference calibrator. We do several tests to check the performance of the calibration. We find it self-consistent when comparing repeated observations of the same objects, with a good overall accuracy to the AB system which we estimate to be at the 2 per cent precision level and no significant trends as a function of narrow band filter or wavelength. Repeated observations allow us to build a spatial map of the illumination pattern of the system. We also check the wavelength dependence of the calibration comparing to stellar spectra. We find that using only blue stars reduces the effects of variations in the stellar template fitting to broad-band colours, improving the overall precision of the calibration to around 1 per cent and its wavelength uniformity. The photometric redshift performance obtained with the PAUS data attests to the validity of our calibration to reach the PAUS science goals.
ABSTRACT
PAUCam is an innovative optical narrow-band imager mounted at the William Herschel Telescope built for the Physics of the Accelerating Universe Survey (PAUS). Its set of 40 filters results ...in images that are complex to calibrate, with specific instrumental signatures that cannot be processed with traditional data reduction techniques. In this paper, we present two pipelines developed by the PAUS data management team with the objective of producing science-ready catalogues from the uncalibrated raw images. The Nightly pipeline takes care of entire image processing, with bespoke algorithms for photometric calibration and scatter-light correction. The Multi-Epoch and Multi-Band Analysis pipeline performs forced photometry over a reference catalogue to optimize the photometric redshift (photo-z) performance. We verify against spectroscopic observations that the current approach delivers an inter-band photometric calibration of 0.8 per cent across the 40 narrow-band set. The large volume of data produced every night and the rapid survey strategy feedback constraints require operating both pipelines in the Port d’Informació Cientifica data centre with intense parallelization. While alternative algorithms for further improvements in photo-z performance are under investigation, the image calibration and photometry presented in this work already enable state-of-the-art photo-z down to iAB = 23.0.
The steady-state operation of the Francis-99, Tokke turbine 1-3 has been simulated numerically at different loads using the open source, CAD and CFD software, SALOME 4 Code_Saturne 5. The full 3D ...mesh of the Tokke turbine provided for the Second Francis-99 Workshop has been adapted and modified to work with the solver. Results are compared for the frozen-rotor and the unsteady, conservative sliding mesh approach over three operating points, showing that good agreement with the experimental data is obtained with both models without having to tune the CFD models for each operating point. Approaches to the simulation of transient operation are also presented with results of work in progress.
Gaia Data Release 3 Arenou, F.; Lammers, U. L.; Mignard, F. ...
Astronomy and astrophysics (Berlin),
06/2023, Volume:
674, Issue:
A1
Journal Article, Web Resource
Peer reviewed
Open access
Context.
We present the third data release of the European Space Agency’s
Gaia
mission,
Gaia
DR3. This release includes a large variety of new data products, notably a much expanded radial velocity ...survey and a very extensive astrophysical characterisation of
Gaia
sources.
Aims.
We outline the content and the properties of
Gaia
DR3, providing an overview of the main improvements in the data processing in comparison with previous data releases (where applicable) and a brief discussion of the limitations of the data in this release.
Methods.
The
Gaia
DR3 catalogue is the outcome of the processing of raw data collected with the
Gaia
instruments during the first 34 months of the mission by the
Gaia
Data Processing and Analysis Consortium.
Results.
The
Gaia
DR3 catalogue contains the same source list, celestial positions, proper motions, parallaxes, and broad band photometry in the
G
,
G
BP
, and
G
RP
pass-bands already present in the Early Third Data Release,
Gaia
EDR3.
Gaia
DR3 introduces an impressive wealth of new data products. More than 33 million objects in the ranges
G
RVS
< 14 and 3100 <
T
eff
< 14 500, have new determinations of their mean radial velocities based on data collected by
Gaia
. We provide
G
RVS
magnitudes for most sources with radial velocities, and a line broadening parameter is listed for a subset of these. Mean
Gaia
spectra are made available to the community. The
Gaia
DR3 catalogue includes about 1 million mean spectra from the radial velocity spectrometer, and about 220 million low-resolution blue and red prism photometer BP/RP mean spectra. The results of the analysis of epoch photometry are provided for some 10 million sources across 24 variability types.
Gaia
DR3 includes astrophysical parameters and source class probabilities for about 470 million and 1500 million sources, respectively, including stars, galaxies, and quasars. Orbital elements and trend parameters are provided for some 800 000 astrometric, spectroscopic and eclipsing binaries. More than 150 000 Solar System objects, including new discoveries, with preliminary orbital solutions and individual epoch observations are part of this release. Reflectance spectra derived from the epoch BP/RP spectral data are published for about 60 000 asteroids. Finally, an additional data set is provided, namely the
Gaia
Andromeda Photometric Survey, consisting of the photometric time series for all sources located in a 5.5 degree radius field centred on the Andromeda galaxy.
Conclusions.
This data release represents a major advance with respect to
Gaia
DR2 and
Gaia
EDR3 because of the unprecedented quantity, quality, and variety of source astrophysical data. To date this is the largest collection of all-sky spectrophotometry, radial velocities, variables, and astrophysical parameters derived from both low- and high-resolution spectra and includes a spectrophotometric and dynamical survey of SSOs of the highest accuracy. The non-single star content surpasses the existing data by orders of magnitude. The quasar host and galaxy light profile collection is the first such survey that is all sky and space based. The astrophysical information provided in
Gaia
DR3 will unleash the full potential of
Gaia
’s exquisite astrometric, photometric, and radial velocity surveys.
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6.
Gaia Early Data Release 3 Brown, A. G. A.; Prusti, T.; Eyer, L. ...
Astronomy and astrophysics (Berlin),
05/2021, Volume:
649
Journal Article, Web Resource
Peer reviewed
Open access
Context.
We present the early installment of the third
Gaia
data release,
Gaia
EDR3, consisting of astrometry and photometry for 1.8 billion sources brighter than magnitude 21, complemented with the ...list of radial velocities from
Gaia
DR2.
Aims.
A summary of the contents of
Gaia
EDR3 is presented, accompanied by a discussion on the differences with respect to
Gaia
DR2 and an overview of the main limitations which are present in the survey. Recommendations are made on the responsible use of
Gaia
EDR3 results.
Methods.
The raw data collected with the
Gaia
instruments during the first 34 months of the mission have been processed by the
Gaia
Data Processing and Analysis Consortium and turned into this early third data release, which represents a major advance with respect to
Gaia
DR2 in terms of astrometric and photometric precision, accuracy, and homogeneity.
Results. Gaia
EDR3 contains celestial positions and the apparent brightness in
G
for approximately 1.8 billion sources. For 1.5 billion of those sources, parallaxes, proper motions, and the (
G
BP
−
G
RP
) colour are also available. The passbands for
G
,
G
BP
, and
G
RP
are provided as part of the release. For ease of use, the 7 million radial velocities from
Gaia
DR2 are included in this release, after the removal of a small number of spurious values. New radial velocities will appear as part of
Gaia
DR3. Finally,
Gaia
EDR3 represents an updated materialisation of the celestial reference frame (CRF) in the optical, the
Gaia
-CRF3, which is based solely on extragalactic sources. The creation of the source list for
Gaia
EDR3 includes enhancements that make it more robust with respect to high proper motion stars, and the disturbing effects of spurious and partially resolved sources. The source list is largely the same as that for
Gaia
DR2, but it does feature new sources and there are some notable changes. The source list will not change for
Gaia
DR3.
Conclusions. Gaia
EDR3 represents a significant advance over
Gaia
DR2, with parallax precisions increased by 30 per cent, proper motion precisions increased by a factor of 2, and the systematic errors in the astrometry suppressed by 30–40% for the parallaxes and by a factor ~2.5 for the proper motions. The photometry also features increased precision, but above all much better homogeneity across colour, magnitude, and celestial position. A single passband for
G
,
G
BP
, and
G
RP
is valid over the entire magnitude and colour range, with no systematics above the 1% level
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Gaia Early Data Release 3 Carrasco, J. M.; Cooper, W. J.; Brown, A. G. A. ...
Astronomy and astrophysics (Berlin),
05/2021, Volume:
649
Journal Article, Web Resource
Peer reviewed
Open access
Aims.
We produce a clean and well-characterised catalogue of objects within 100 pc of the Sun from the
Gaia
Early Data Release 3. We characterise the catalogue through comparisons to the full data ...release, external catalogues, and simulations. We carry out a first analysis of the science that is possible with this sample to demonstrate its potential and best practices for its use.
Methods.
Theselection of objects within 100 pc from the full catalogue used selected training sets, machine-learning procedures, astrometric quantities, and solution quality indicators to determine a probability that the astrometric solution is reliable. The training set construction exploited the astrometric data, quality flags, and external photometry. For all candidates we calculated distance posterior probability densities using Bayesian procedures and mock catalogues to define priors. Any object with reliable astrometry and a non-zero probability of being within 100 pc is included in the catalogue.
Results.
We have produced a catalogue of 331 312 objects that we estimate contains at least 92% of stars of stellar type M9 within 100 pc of the Sun. We estimate that 9% of the stars in this catalogue probably lie outside 100 pc, but when the distance probability function is used, a correct treatment of this contamination is possible. We produced luminosity functions with a high signal-to-noise ratio for the main-sequence stars, giants, and white dwarfs. We examined in detail the Hyades cluster, the white dwarf population, and wide-binary systems and produced candidate lists for all three samples. We detected local manifestations of several streams, superclusters, and halo objects, in which we identified 12 members of
Gaia
Enceladus. We present the first direct parallaxes of five objects in multiple systems within 10 pc of the Sun.
Conclusions.
We provide the community with a large, well-characterised catalogue of objects in the solar neighbourhood. This is a primary benchmark for measuring and understanding fundamental parameters and descriptive functions in astronomy.
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Gaia Data Release 3 Arenou, F.; Faigler, S.; Kervella, P. ...
Astronomy and astrophysics (Berlin),
06/2023, Volume:
674
Journal Article, Web Resource
Peer reviewed
Open access
Context.
The
Gaia
DR3 catalogue contains, for the first time, about 800 000 solutions with either orbital elements or trend parameters for astrometric, spectroscopic, and eclipsing binaries, and ...combinations of these three.
Aims.
With this paper, we aim to illustrate the huge potential of this large non-single-star catalogue.
Methods.
Using the orbital solutions and models of the binaries, we have built a catalogue of tens of thousands of stellar masses or lower limits thereof, some with consistent flux ratios. Properties concerning the completeness of the binary catalogues are discussed, statistical features of the orbital elements are explained, and a comparison with other catalogues is performed.
Results.
Illustrative applications are proposed for binaries across the Hertzsprung-Russell Diagram (HRD). Binarity is studied in the giant branch and a search for genuine spectroscopic binaries among long-period variables is performed. The discovery of new EL CVn systems illustrates the potential of combining variability and binarity catalogues. Potential compact object companions are presented, mainly white dwarf companions or double degenerates, but one candidate neutron star is also found. Towards the bottom of the main sequence, the orbits of previously suspected binary ultracool dwarfs are determined and new candidate binaries are discovered. The long awaited contribution of
Gaia
to the analysis of the substellar regime shows the brown dwarf desert around solar-type stars using true rather than minimum masses, and provides new important constraints on the occurrence rates of substellar companions to M dwarfs. Several dozen new exoplanets are proposed, including two with validated orbital solutions and one super-Jupiter orbiting a white dwarf, all being candidates requiring confirmation. Besides binarity, higher order multiple systems are also found.
Conclusions.
By increasing the number of known binary orbits by more than one order of magnitude,
Gaia
DR3 will provide a rich reservoir of dynamical masses and an important contribution to the analysis of stellar multiplicity.
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This is a corrigendum for Gaia Collaboration (2021). It corrects errors in Sects. 6.3.2 and 7.2 and Appendix A, which erroneously state that the correction to theG-band fluxes and magnitudes ...presented in Riello et al. (2021) (their Table 5) should be applied to sources in Gaia EDR3 with six-parameter astrometric solutions. In fact, the corrections should be applied to sources with twoparameter or six-parameter astrometric solutions. The corrected Astronomical Data Query Language (ADQL) query and Python source code from Appendix A are presented in the new version of Appendix A below. Following the discovery of the above error, a more detailed investigation was done for the sources with two-parameter (2-p) astrometric solutions. Out of the 344 million 2-p sources present in Gaia EDR3, about 20 million have an astrometric solution in which the actual source colour was used instead of a default colour. This means that for these 20 million 2-p sources the Gband correction should actually not be applied. These sources are mostly faint, with 96% at magnitudes G > 20, and for 75% of these 20 million sources the correction that is (wrongly) applied amounts to less than 4 milli-magnitudes. It was thus decided not to make a special effort to exclude these sources from the correction. Should a user of the Gaia EDR3 data wish to undo the wrong correction for one or more of these 20 million sources, the list of source IDs and applied corrections can be provided on request. Appendix A: G-band corrections for sources with two-parameter or six-parameter astrometric solutions Figure A.1 shows how to formulate an ADQL query, to be executed in the Gaia EDR3 archive, that contains an on-the-fly calculation of the corrected G-band fluxes or magnitudes. These queries are somewhat complex and create a performance overhead. Hence downloading the requisite Gaia EDR3 fields and calculating the corrections a posteriori may be more efficient. Example Python code to do this is included in Fig. A.2. The Python code is also available as a Jupyter notebook1. Appendix A: G-band corrections for sources with two-parameter or six-parameter astrometric solutions Figure A.1 shows how to formulate an ADQL query, to be executed in the Gaia EDR3 archive, that contains an on-the-fly calculation of the corrected G-band fluxes or magnitudes. These queries are somewhat complex and create a performance overhead. Hence downloading the requisite Gaia EDR3 fields and calculating the corrections a posteriori may be more efficient. Example Python code to do this is included in Fig. A.2. The Python code is also available as a Jupyter notebook.
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Gaia Data Release 3 de Laverny, P.; Spagna, A.; Vallenari, A. ...
Astronomy and astrophysics (Berlin),
06/2023, Volume:
674
Journal Article, Web Resource
Peer reviewed
Open access
Context.
The motion of stars has been used to reveal details of the complex history of the Milky Way, in constant interaction with its environment. Nevertheless, to reconstruct the Galactic history ...puzzle in its entirety, the chemo-physical characterisation of stars is essential. Previous
Gaia
data releases were supported by a smaller, heterogeneous, and spatially biased mixture of chemical data from ground-based observations.
Aims.
Gaia
Data Release 3 opens a new era of all-sky spectral analysis of stellar populations thanks to the nearly 5.6 million stars observed by the Radial Velocity Spectrometer (RVS) and parametrised by the GSP-Spec module. In this work, we aim to demonstrate the scientific quality of
Gaia
’s Milky Way chemical cartography through a chemo-dynamical analysis of disc and halo populations.
Methods.
Stellar atmospheric parameters and chemical abundances provided by
Gaia
DR3 spectroscopy are combined with DR3 radial velocities and EDR3 astrometry to analyse the relationships between chemistry and Milky Way structure, stellar kinematics, and orbital parameters.
Results.
The all-sky
Gaia
chemical cartography allows a powerful and precise chemo-dynamical view of the Milky Way with unprecedented spatial coverage and statistical robustness. First, it reveals the strong vertical symmetry of the Galaxy and the flared structure of the disc. Second, the observed kinematic disturbances of the disc – seen as phase space correlations – and kinematic or orbital substructures are associated with chemical patterns that favour stars with enhanced metallicities and lower
α
/Fe abundance ratios compared to the median values in the radial distributions. This is detected both for young objects that trace the spiral arms and older populations. Several
α
, iron-peak elements and at least one heavy element trace the thin and thick disc properties in the solar cylinder. Third, young disc stars show a recent chemical impoverishment in several elements. Fourth, the largest chemo-dynamical sample of open clusters analysed so far shows a steepening of the radial metallicity gradient with age, which is also observed in the young field population. Finally, the
Gaia
chemical data have the required coverage and precision to unveil galaxy accretion debris and heated disc stars on halo orbits through their
α
/Fe ratio, and to allow the study of the chemo-dynamical properties of globular clusters.
Conclusions.
Gaia
DR3 chemo-dynamical diagnostics open new horizons before the era of ground-based wide-field spectroscopic surveys. They unveil a complex Milky Way that is the outcome of an eventful evolution, shaping it to the present day.
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