arXiv: Instrumentation and Methods for Astrophysics, 2019
The current status of and motivation for the 4MOST Survey Strategy, as developed by the Consortiu... more The current status of and motivation for the 4MOST Survey Strategy, as developed by the Consortium science team, are presented here. Key elements of the strategy are described, such as sky coverage, number of visits and total exposure times in different parts of the sky, and how to deal with different observing conditions. The task of organising the strategy is not simple, with many different surveys that have vastly different target brightnesses and densities, sample completeness levels, and signal-to-noise requirements. We introduce here a number of concepts that we will use to ensure all surveys are optimised. Astronomers who are planning to submit a Participating Survey proposal are strongly encouraged to read this article and any relevant 4MOST Survey articles in this issue of The Messenger such that they can optimally complement and benefit from the planned surveys of the 4MOST Consortium.
We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide... more We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs ($R = \lambda/\Delta\lambda \sim 6500$), and 812 fibres transferring light to the high-resolution spectrograph ($R \sim 20\,000$). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Survey...
Monthly Notices of the Royal Astronomical Society, 2021
SPIDERS is the spectroscopic follow-up effort of the Sloan Digital Sky Survey IV (SDSS-IV) projec... more SPIDERS is the spectroscopic follow-up effort of the Sloan Digital Sky Survey IV (SDSS-IV) project for the identification of X-ray selected galaxy clusters. We present our catalogue of 2740 visually inspected galaxy clusters as part of the SDSS Data Release 16 (DR16). Here we detail the target selection, our methods for validation of the candidate clusters, performance of the survey, the construction of the final sample, and a full description of what is found in the catalogue. Of the sample, the median number of members per cluster is approximately 10, with 818 having 15 or greater. We find that we are capable of validating over 99 per cent of clusters when five redshifts are obtained below z < 0.3 and when nine redshifts are obtained above z > 0.3. We discuss the improvements in this catalogue’s identification of cluster using 33 340 redshifts, with Δzphot/Δzspec ∼ 100, over other photometric and spectroscopic surveys, as well as presenting an update to previous (σ–LX) and (...
We provide the source list for the first 5.5 surveyed square degrees of the XMM-LSS, with a total... more We provide the source list for the first 5.5 surveyed square degrees of the XMM-LSS, with a total of 3385 point-like or extended sources above a detection likelihood of 15 in either 0.5-2 or 2-10keV bands. The table at CDS contains the main parameters, while further parameters and data products (X-ray images and optical thumbnails) are available in the Milan
We describe the properties of X-ray point-like sources detected over 4.2 sq. degs. of the largest... more We describe the properties of X-ray point-like sources detected over 4.2 sq. degs. of the largest contiguous survey with XMM-Newton to date (the XMM-LSS survey) to fluxes of F2-10 keV 8x10-15 erg/s/cm2 and F0.5-2 keV 2x10-15 erg/s/cm2 respectively. For 1200 sources in the soft band, we find a two-point angular correlation function (ACF) signal similar to previous work, but no correlation for 400 sources in the hard band. A sample of 200 faint sources with hard X-ray spectra does show a 2-3 sigma positive signal with a power-law normalization theta0>40 arcsec. We discuss implications, including the fact that a large correlation length for obscured AGN is inconsistent with simple AGN Unification based on orientation only.
We present a sample of 29 galaxy clusters from the XMM-LSS survey over an area of some 5 deg2 out... more We present a sample of 29 galaxy clusters from the XMM-LSS survey over an area of some 5 deg2 out to a redshift of z = 1.05. The sample clusters, which represent about half of the X-ray clusters identified in the region, follow well defined X-ray selection criteria and are all spectroscopically confirmed. For all clusters, we provide X-ray luminosities and temperatures
We present the XMM-LSS cluster catalogue corresponding to t he CFHTLS D1 area. The list contains ... more We present the XMM-LSS cluster catalogue corresponding to t he CFHTLS D1 area. The list contains 13 spectroscopically confirmed, X-ray select d galaxy clusters over 0.8 deg 2 to a redshift of unity and so constitutes the highest density sam ple of clusters to date. Cluster Xray bolometric luminosities range from 0.03 to 5 × 1044 erg s−1. In this study, we describe our catalogue construction procedure: from the detection of Xray cluster candidates to the compilation of a spectroscopically confirmed cluster sample with an explicit selection function. The procedure further provides basic X-ray products such as clu ster temperature, flux and luminosity. We detected slightly more clusters with a (0.5-2.0 k eV) X-ray fluxes of> 2×10−14 erg s−1 cm−2 than we expected based on expectations from deep ROSAT surve y . W also present the Luminosity-Temperature relation for our 9 brightest ob jects possessing a reliable temperature determination. The slope is in good agreement with the l ocal ...
Context. The eROSITA X-ray telescope onboard the Spectrum-Roentgen-Gamma (SRG) observatory combin... more Context. The eROSITA X-ray telescope onboard the Spectrum-Roentgen-Gamma (SRG) observatory combines a large field of view and a large collecting area in the energy range between ∼0.2 and ∼8.0 keV with the capability to perform uniform scanning observations of large sky areas. Aims. SRG/eROSITA performed scanning observations of the ∼140 square degrees eROSITA Final Equatorial Depth Survey field (the eFEDS field) as part of its performance verification phase ahead of the planned four years of all-sky scanning operations. The observing time of eFEDS was chosen to slightly exceed the depth expected in an equatorial field after the completion of the all-sky survey. While verifying the capability of eROSITA to perform large area uniform surveys and serving as a test and training dataset to establish calibration and data analysis procedures, the eFEDS survey also constitutes the largest contiguous soft X-ray survey at this depth to date, supporting a range of early eROSITA survey science ...
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the primary instrument on t... more eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the primary instrument on the Spectrum-Roentgen-Gamma (SRG) mission, which was successfully launched on July 13, 2019, from the Baikonour cosmodrome. After the commissioning of the instrument and a subsequent calibration and performance verification phase, eROSITA started a survey of the entire sky on December 13, 2019. By the end of 2023, eight complete scans of the celestial sphere will have been performed, each lasting six months. At the end of this program, the eROSITA all-sky survey in the soft X-ray band (0.2–2.3 keV) will be about 25 times more sensitive than the ROSAT All-Sky Survey, while in the hard band (2.3–8 keV) it will provide the first ever true imaging survey of the sky. The eROSITA design driving science is the detection of large samples of galaxy clusters up to redshiftsz> 1 in order to study the large-scale structure of the universe and test cosmological models including Dark Energy. In addi...
Context. The second Gaia data release (Gaia DR2) provides precise five-parameter astrometric data... more Context. The second Gaia data release (Gaia DR2) provides precise five-parameter astrometric data (positions, proper motions, and parallaxes) for an unprecedented number of sources (more than 1.3 billion, mostly stars). This new wealth of data will enable the undertaking of statistical analysis of many astrophysical problems that were previously infeasible for lack of reliable astrometry, and in particular because of the lack of parallaxes. However, the use of this wealth of astrometric data comes with a specific challenge: how can the astrophysical parameters of interest be properly inferred from these data? Aims. The main focus of this paper, but not the only focus, is the issue of the estimation of distances from parallaxes, possibly combined with other information. We start with a critical review of the methods traditionally used to obtain distances from parallaxes and their shortcomings. Then we provide guidelines on how to use parallaxes more efficiently to estimate distances ...
arXiv: Instrumentation and Methods for Astrophysics, 2019
The current status of and motivation for the 4MOST Survey Strategy, as developed by the Consortiu... more The current status of and motivation for the 4MOST Survey Strategy, as developed by the Consortium science team, are presented here. Key elements of the strategy are described, such as sky coverage, number of visits and total exposure times in different parts of the sky, and how to deal with different observing conditions. The task of organising the strategy is not simple, with many different surveys that have vastly different target brightnesses and densities, sample completeness levels, and signal-to-noise requirements. We introduce here a number of concepts that we will use to ensure all surveys are optimised. Astronomers who are planning to submit a Participating Survey proposal are strongly encouraged to read this article and any relevant 4MOST Survey articles in this issue of The Messenger such that they can optimally complement and benefit from the planned surveys of the 4MOST Consortium.
We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide... more We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs ($R = \lambda/\Delta\lambda \sim 6500$), and 812 fibres transferring light to the high-resolution spectrograph ($R \sim 20\,000$). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Survey...
Monthly Notices of the Royal Astronomical Society, 2021
SPIDERS is the spectroscopic follow-up effort of the Sloan Digital Sky Survey IV (SDSS-IV) projec... more SPIDERS is the spectroscopic follow-up effort of the Sloan Digital Sky Survey IV (SDSS-IV) project for the identification of X-ray selected galaxy clusters. We present our catalogue of 2740 visually inspected galaxy clusters as part of the SDSS Data Release 16 (DR16). Here we detail the target selection, our methods for validation of the candidate clusters, performance of the survey, the construction of the final sample, and a full description of what is found in the catalogue. Of the sample, the median number of members per cluster is approximately 10, with 818 having 15 or greater. We find that we are capable of validating over 99 per cent of clusters when five redshifts are obtained below z < 0.3 and when nine redshifts are obtained above z > 0.3. We discuss the improvements in this catalogue’s identification of cluster using 33 340 redshifts, with Δzphot/Δzspec ∼ 100, over other photometric and spectroscopic surveys, as well as presenting an update to previous (σ–LX) and (...
We provide the source list for the first 5.5 surveyed square degrees of the XMM-LSS, with a total... more We provide the source list for the first 5.5 surveyed square degrees of the XMM-LSS, with a total of 3385 point-like or extended sources above a detection likelihood of 15 in either 0.5-2 or 2-10keV bands. The table at CDS contains the main parameters, while further parameters and data products (X-ray images and optical thumbnails) are available in the Milan
We describe the properties of X-ray point-like sources detected over 4.2 sq. degs. of the largest... more We describe the properties of X-ray point-like sources detected over 4.2 sq. degs. of the largest contiguous survey with XMM-Newton to date (the XMM-LSS survey) to fluxes of F2-10 keV 8x10-15 erg/s/cm2 and F0.5-2 keV 2x10-15 erg/s/cm2 respectively. For 1200 sources in the soft band, we find a two-point angular correlation function (ACF) signal similar to previous work, but no correlation for 400 sources in the hard band. A sample of 200 faint sources with hard X-ray spectra does show a 2-3 sigma positive signal with a power-law normalization theta0>40 arcsec. We discuss implications, including the fact that a large correlation length for obscured AGN is inconsistent with simple AGN Unification based on orientation only.
We present a sample of 29 galaxy clusters from the XMM-LSS survey over an area of some 5 deg2 out... more We present a sample of 29 galaxy clusters from the XMM-LSS survey over an area of some 5 deg2 out to a redshift of z = 1.05. The sample clusters, which represent about half of the X-ray clusters identified in the region, follow well defined X-ray selection criteria and are all spectroscopically confirmed. For all clusters, we provide X-ray luminosities and temperatures
We present the XMM-LSS cluster catalogue corresponding to t he CFHTLS D1 area. The list contains ... more We present the XMM-LSS cluster catalogue corresponding to t he CFHTLS D1 area. The list contains 13 spectroscopically confirmed, X-ray select d galaxy clusters over 0.8 deg 2 to a redshift of unity and so constitutes the highest density sam ple of clusters to date. Cluster Xray bolometric luminosities range from 0.03 to 5 × 1044 erg s−1. In this study, we describe our catalogue construction procedure: from the detection of Xray cluster candidates to the compilation of a spectroscopically confirmed cluster sample with an explicit selection function. The procedure further provides basic X-ray products such as clu ster temperature, flux and luminosity. We detected slightly more clusters with a (0.5-2.0 k eV) X-ray fluxes of> 2×10−14 erg s−1 cm−2 than we expected based on expectations from deep ROSAT surve y . W also present the Luminosity-Temperature relation for our 9 brightest ob jects possessing a reliable temperature determination. The slope is in good agreement with the l ocal ...
Context. The eROSITA X-ray telescope onboard the Spectrum-Roentgen-Gamma (SRG) observatory combin... more Context. The eROSITA X-ray telescope onboard the Spectrum-Roentgen-Gamma (SRG) observatory combines a large field of view and a large collecting area in the energy range between ∼0.2 and ∼8.0 keV with the capability to perform uniform scanning observations of large sky areas. Aims. SRG/eROSITA performed scanning observations of the ∼140 square degrees eROSITA Final Equatorial Depth Survey field (the eFEDS field) as part of its performance verification phase ahead of the planned four years of all-sky scanning operations. The observing time of eFEDS was chosen to slightly exceed the depth expected in an equatorial field after the completion of the all-sky survey. While verifying the capability of eROSITA to perform large area uniform surveys and serving as a test and training dataset to establish calibration and data analysis procedures, the eFEDS survey also constitutes the largest contiguous soft X-ray survey at this depth to date, supporting a range of early eROSITA survey science ...
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the primary instrument on t... more eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the primary instrument on the Spectrum-Roentgen-Gamma (SRG) mission, which was successfully launched on July 13, 2019, from the Baikonour cosmodrome. After the commissioning of the instrument and a subsequent calibration and performance verification phase, eROSITA started a survey of the entire sky on December 13, 2019. By the end of 2023, eight complete scans of the celestial sphere will have been performed, each lasting six months. At the end of this program, the eROSITA all-sky survey in the soft X-ray band (0.2–2.3 keV) will be about 25 times more sensitive than the ROSAT All-Sky Survey, while in the hard band (2.3–8 keV) it will provide the first ever true imaging survey of the sky. The eROSITA design driving science is the detection of large samples of galaxy clusters up to redshiftsz> 1 in order to study the large-scale structure of the universe and test cosmological models including Dark Energy. In addi...
Context. The second Gaia data release (Gaia DR2) provides precise five-parameter astrometric data... more Context. The second Gaia data release (Gaia DR2) provides precise five-parameter astrometric data (positions, proper motions, and parallaxes) for an unprecedented number of sources (more than 1.3 billion, mostly stars). This new wealth of data will enable the undertaking of statistical analysis of many astrophysical problems that were previously infeasible for lack of reliable astrometry, and in particular because of the lack of parallaxes. However, the use of this wealth of astrometric data comes with a specific challenge: how can the astrophysical parameters of interest be properly inferred from these data? Aims. The main focus of this paper, but not the only focus, is the issue of the estimation of distances from parallaxes, possibly combined with other information. We start with a critical review of the methods traditionally used to obtain distances from parallaxes and their shortcomings. Then we provide guidelines on how to use parallaxes more efficiently to estimate distances ...
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