Showing papers by "Edwin A. Valentijn published in 2019"
TL;DR: The Kilo-Degree Survey (KiDS) dataset as mentioned in this paper is a large-scale optical wide-field imaging survey with the OmegaCAM camera at the VLT Survey Telescope, specifically designed for measuring weak gravitational lensing by galaxies and large scale structure.
Abstract: Context . The Kilo-Degree Survey (KiDS) is an ongoing optical wide-field imaging survey with the OmegaCAM camera at the VLT Survey Telescope, specifically designed for measuring weak gravitational lensing by galaxies and large-scale structure. When completed it will consist of 1350 square degrees imaged in four filters (ugri ).Aims . Here we present the fourth public data release which more than doubles the area of sky covered by data release 3. We also include aperture-matched Z Y J H K s photometry from our partner VIKING survey on the VISTA telescope in the photometry catalogue. We illustrate the data quality and describe the catalogue content.Methods . Two dedicated pipelines are used for the production of the optical data. The ASTRO-WISE information system is used for the production of co-added images in the four survey bands, while a separate reduction of the r -band images using the THELI pipeline is used to provide a source catalogue suitable for the core weak lensing science case. All data have been re-reduced for this data release using the latest versions of the pipelines. The VIKING photometry is obtained as forced photometry on the THELI sources, using a re-reduction of the VIKING data that starts from the VISTA pawprints. Modifications to the pipelines with respect to earlier releases are described in detail. The photometry is calibrated to the Gaia DR2 G band using stellar locus regression.Results . In this data release a total of 1006 square-degree survey tiles with stacked ugri images are made available, accompanied by weight maps, masks, and single-band source lists. We also provide a multi-band catalogue based on r -band detections, including homogenized photometry and photometric redshifts, for the whole dataset. Mean limiting magnitudes (5σ in a 2″ aperture) and the tile-to-tile rms scatter are 24.23 ± 0.12, 25.12 ± 0.14, 25.02 ± 0.13, 23.68 ± 0.27 in ugri , respectively, and the mean r -band seeing is 0.″70.
192 citations
TL;DR: The Kilo-Degree Survey (KiDS) dataset as discussed by the authors is a large scale optical wide-field imaging survey with the OmegaCAM camera at the VLT Survey Telescope, specifically designed for measuring weak gravitational lensing by galaxies and large scale structure.
Abstract: The Kilo-Degree Survey (KiDS) is an ongoing optical wide-field imaging survey with the OmegaCAM camera at the VLT Survey Telescope, specifically designed for measuring weak gravitational lensing by galaxies and large-scale structure. When completed it will consist of 1350 square degrees imaged in four filters (ugri). Here we present the fourth public data release which more than doubles the area of sky covered by data release 3. We also include aperture-matched ZYJHKs photometry from our partner VIKING survey on the VISTA telescope in the photometry catalogue. We illustrate the data quality and describe the catalogue content. Two dedicated pipelines are used for the production of the optical data. The Astro-WISE information system is used for the production of co-added images in the four survey bands, while a separate reduction of the r-band images using the theli pipeline is used to provide a source catalogue suitable for the core weak lensing science case. All data have been re-reduced for this data release using the latest versions of the pipelines. The VIKING photometry is obtained as forced photometry on the theli sources, using a re-reduction of the VIKING data that starts from the VISTA pawprints. Modifications to the pipelines with respect to earlier releases are described in detail. The photometry is calibrated to the Gaia DR2 G band using stellar locus regression. In this data release a total of 1006 square-degree survey tiles with stacked ugri images are made available, accompanied by weight maps, masks, and single-band source lists. We also provide a multi-band catalogue based on r-band detections, including homogenized photometry and photometric redshifts, for the whole dataset. Mean limiting magnitudes (5 sigma in a 2" aperture) are 24.23, 25.12, 25.02, 23.68 in ugri, respectively, and the mean r-band seeing is 0.70".
121 citations
TL;DR: In this paper, the authors used a Bayesian mixture model approach to measure NGC for 175 LSB (23 ≤ [mag arcsec-2] ≤ 28) galaxies in the Fornax cluster using the FDS data; this is the largest sample of low mass galaxies so-far analysed for this kind of study.
Abstract: The halo masses Mhalo of low surface brightness (LSB) galaxies are critical measurements for understanding their formation processes. One promising method to estimate a galaxy's Mhalo is to exploit the empirical scaling relation between Mhalo and the number of associated globular clusters (NGC). We use a Bayesian mixture model approach to measure NGC for 175 LSB (23 ≤ [mag arcsec-2] ≤ 28) galaxies in the Fornax cluster using the Fornax Deep Survey (FDS) data; this is the largest sample of low mass galaxies so-far analysed for this kind of study. The proximity of the Fornax cluster means that we can measure galaxies with much smaller physical sizes (0.3 ≤ re, r [kpc] ≤ 9.5) compared to previous studies of the GC systems of LSB galaxies, probing stellar masses down to M* ˜ 105M⊙. The sample also includes 12 ultra-diffuse galaxies (UDGs), with projected r-band half-light radii greater than 1.5 kpc. Our results are consistent with an extrapolation of the M* - Mhalo relation predicted from abundance matching. In particular, our UDG measurements are consistent with dwarf sized halos, having typical masses between 1010 and 1011M⊙. Overall, our UDG sample is statistically indistinguishable from smaller LSB galaxies in the same magnitude range. We do not find any candidates likely to be as rich as some of those found in the Coma cluster. We suggest that environment might play a role in producing GC-rich LSB galaxies.
63 citations
University of Groningen1, University of Oulu2, Astronomical Observatory of Capodimonte3, European Southern Observatory4, Heidelberg University5, University of Naples Federico II6, INAF7, University of Turku8, Smithsonian Astrophysical Observatory9, University of Vienna10, Spanish National Research Council11, University of La Laguna12
TL;DR: In this article, the authors used the Fornax Deep Survey Dwarf galaxy Catalog (FDSDC) to study how the number density of galaxies, galaxy colors and structure change as a function of the cluster-centric distance, used as a proxy for the galactic environment and infall time.
Abstract: Context . Dwarf galaxies are the most common type of galaxies in galaxy clusters. Due to their low mass, they are more vulnerable to environmental effects than massive galaxies, and are thus optimal for studying the effects of the environment on galaxy evolution. By comparing the properties of dwarf galaxies with different masses, morphological types, and cluster-centric distances we can obtain information about the physical processes in clusters that play a role in the evolution of these objects and shape their properties. The Fornax Deep Survey Dwarf galaxy Catalog (FDSDC) includes 564 dwarf galaxies in the Fornax cluster and the in-falling Fornax A subgroup. This sample allows us to perform a robust statistical analysis of the structural and stellar population differences in the range of galactic environments within the Fornax cluster.Aims . By comparing our results with works concerning other clusters and the theoretical knowledge of the environmental processes taking place in galaxy clusters, we aim to understand the main mechanisms transforming galaxies in the Fornax cluster.Methods . We have exploited the FDSDC to study how the number density of galaxies, galaxy colors and structure change as a function of the cluster-centric distance, used as a proxy for the galactic environment and in-fall time. We also used deprojection methods to transform the observed shape and density distributions of the galaxies into the intrinsic physical values. These measurements are then compared with predictions of simple theoretical models of the effects of harassment and ram pressure stripping on galaxy structure. We used stellar population models to estimate the stellar masses, metallicities and ages of the dwarf galaxies. We compared the properties of the dwarf galaxies in Fornax with those in the other galaxy clusters with different masses.Results . We present the standard scaling relations for dwarf galaxies, which are the size-luminosity, Sersic n -magnitude and color-magnitude relations. New in this paper is that we find a different behavior for the bright dwarfs (−18.5 mag r ′ r ′ > −16 mag): While considering galaxies in the same magnitude-bins, we find that, while for fainter dwarfs the g ′−r ′ color is redder for lower surface brightness objects (as expected from fading stellar populations), for brighter dwarfs the color is redder for the higher surface brightness and higher Sersic n objects. The trend of the bright dwarfs might be explained by those galaxies being affected by harassment and by slower quenching of star formation in their inner parts. As the fraction of early-type dwarfs with respect to late-types increases toward the central parts of the cluster, the color-surface brightness trends are also manifested in the cluster-centric trends, confirming that it is indeed the environment that changes the galaxies. We also estimate the strength of the ram-pressure stripping, tidal disruption, and harassment in the Fornax cluster, and find that our observations are consistent with the theoretically expected ranges of galaxy properties where each of those mechanisms dominate. We furthermore find that the luminosity function, color–magnitude relation, and axis-ratio distribution of the dwarfs in the center of the Fornax cluster are similar to those in the center of the Virgo cluster. This indicates that in spite of the fact that the Virgo is six times more massive, their central dwarf galaxy populations appear similar in the relations studied by us.
45 citations
TL;DR: In this article, the authors compared the slope and intrinsic scatter of color-magnitude relations (CMRs) of three nearby clusters, Fornax, Virgo, and Coma, to understand the stellar population content of early-typedwarf galaxies.
Abstract: Aims: To understand the stellar population content of early-typedwarf galaxies (dEs) and their environmental dependence, we compare theslopes and intrinsic scatter of color-magnitude relations (CMRs) forthree nearby clusters, Fornax, Virgo, and Coma. Additionally, we presentand compare internal color profiles of these galaxies to identifycentral blue regions with younger stars. Methods: We use theimaging of the HST/ACS Fornax cluster in the magnitude range of -18.7≤ Mg' ≤ -16.0 to derive magnitudes, colors, and colorprofiles, which we compare with literature measurements from the HST/ACSVirgo and Coma Cluster Survey. We take advantage of HST accuracy toinvestigate and parameterize the (g'-z') color profiles of these dEs. Results: Based on analysis of the color profiles, we report on alarge number of dEs with young stellar populations at their center inall three clusters. While for Virgo and Coma the number of blue-coreddEs is found to be 85%±2% and 53%±3%, respectively, forFornax, we find that all galaxies have a blue core. We show that bluercores reside in fainter dEs, similar to the trend seen in nucleated dEs.We find no correlation between the luminosity of the galaxy and the sizeof its blue core. Moreover, a comparison of the CMRs of the threeclusters shows that the scatter in the CMR of Virgo is considerablylarger than in the Fornax and Coma clusters. Presenting adaptivesmoothing we show that the galaxies on the blue side of the CMR oftenshow evidence for dust extinction, which strengthens the interpretationthat the bluer colors are due to young stellar populations. We also findthat outliers on the red side of the CMR are more compact than what isexpected for their luminosity. We find several of these red outliers inVirgo, often close to more massive galaxies. No red outlying compactearly-types are found in Fornax and Coma in this magnitude range whilewe find three in the Virgo cluster. We show that the CMR of the Fornaxand Virgo clusters are slightly bluer than that of Coma. We suggest thatthe large number of outliers and larger scatter found for Virgo CMR area result of the alternative assembly history of this cluster.The tables of the measured profiles are only available at the CDS viaanonymous ftp to http://cdsarc.u-strasbg.fr(ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/625/A94.
24 citations
University of Oulu1, University of Groningen2, Astronomical Observatory of Capodimonte3, European Southern Observatory4, Heidelberg University5, University of Naples Federico II6, INAF7, University of Turku8, Smithsonian Astrophysical Observatory9, University of Vienna10, University of La Laguna11, Spanish National Research Council12
TL;DR: The Fornax Deep Survey Dwarf galaxy catalog (FDSDC) as discussed by the authors includes 564 dwarf galaxies in the FDSDC and the in-falling Fornas A subgroup, and the standard scaling relations for the dwarfs and analyze trends as a function of cluster-centric radius.
Abstract: The Fornax Deep Survey Dwarf galaxy Catalog (FDSDC) includes 564 dwarf galaxies in the Fornax cluster and the in-falling Fornax A subgroup. We use the FDSDC galaxies for statistical analysis of the structural and stellar population differences in the range of galactic environments within the Fornax cluster. We present the standard scaling relations for the dwarfs and analyze trends as a function of cluster-centric radius. We find a different behavior for the bright dwarfs (-18.5 mag -16 mag): While considering galaxies in the same magnitude-bins, we find that, while for fainter dwarfs the g'-r' color is redder for lower surface brightness objects (as expected from fading stellar populations), for brighter dwarfs the color is redder for the higher surface brightness and higher Sersic n objects. The trend of the bright dwarfs might be explained by those galaxies being affected by harassment and by slower quenching of star formation in their inner parts. As the fraction of early-type dwarfs with respect to late-types increases toward the central parts of the cluster, the color-surface brightness trends are also manifested in the cluster-centric trends, confirming that it is indeed the environment that changes the galaxies. We also estimate the strengths of the ram-pressure stripping, tidal disruption, and harassment in the Fornax cluster, and find that our observations are consistent with the theoretically expected ranges of galaxy properties where each of those mechanisms dominate. We furthermore find that the luminosity function, color-magnitude relation, and axis-ratio distribution of the dwarfs in the center of the Fornax cluster are similar to those in the center of the Virgo cluster.
23 citations
TL;DR: In this paper, the authors compared the slopes and intrinsic scatter of color-magnitude relations (CMRs) for three nearby clusters, Fornax, Virgo and Coma, to identify central blue regions with younger stars.
Abstract: To understand the stellar population content of dwarf early-type galaxies (dEs) and its environmental dependence, we compare the slopes and intrinsic scatter of color-magnitude relations (CMRs) for three nearby clusters, Fornax, Virgo and Coma. Additionally we present and compare internal color profiles of these galaxies to identify central blue regions with younger stars.
We use the imaging of the HST/ACS Fornax cluster in the magnitude range of -18.7 <= M_g' <= -16.0, to derive magnitudes, colors and color profiles, which we compare with literature measurements.
Based on analysis of the color profiles, we report a large number of dEs with young stellar populations in their center in all three clusters. While for Virgo and Coma the number of blue-cored dEs is found to be 85 +/- 2% and 53 +/- 3% respectively, for Fornax, we find that all galaxies have a blue core. We show that bluer cores reside in fainter dEs, similar to the trend seen in nucleated dEs. We find no correlation between the luminosity of the galaxy and the size of its blue core. Moreover, a comparison of the CMRs of the three clusters shows that the scatter in Virgo's CMR is considerably larger than in the Fornax and Coma clusters. Presenting adaptive smoothing we show that the galaxies on the blue side of the CMR often show evidence for dust extinction, which strengthens the interpretation that the bluer colors are due to young stellar populations. We also find that outliers on the red side of the CMR are more compact than expected for their luminosity. We find several of these red outliers in Virgo, often close to more massive galaxies. No red outlying compact early-types are found in Fornax and Coma in this magnitude range while we find three in the Virgo cluster. We suggest that the large number of outliers and larger scatter found for the Virgo cluster CMR is a result of Virgo's different assembly history.
18 citations
01 Oct 2019
TL;DR: The Euclid Archive System (EAS) as discussed by the authors is a data-centric scientific information system, which is in the core of the Euclid Science Ground System (SGS).
Abstract: We review the architectural design and implementation of the Euclid Archive System (EAS) which is in the core of the Euclid Science Ground System (SGS) and represents a new generation of data-centric scientific information systems. It will handle up to one hundred PBs of mission data in a heterogeneous storage environment and will allow intensive access both to the data and metadata produced during the mission. This paper makes a particular emphasis on the access to science-ready products and interfaces which will be provided for the end-user.