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OSCARS: Taking science research to the next level
Open Science Clusters’ Action for Research and Society (OSCARS) is a EU-funded project that will bring your research data to new audiences and target new use-cases. The FAIR (Findable, Accessible, Interoperable and Reusable) principles allow research data to be used in new and novel ways, with increased citations acknowledging the original researchers and facilities. OSCARS builds on the EOSC (European Open-Science Cloud) science cluster’s outcomes to support open science, by enhancing communication between the science clusters, creating thematic competence centres, improving the outcomes of the science clusters software and services, connecting this activity with other EOSC funded activities, and providing direct funding for open science projects.
Journal Article
The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XXIII. Proper-motion Catalogs and Internal Kinematics
A number of studies based on the data collected by the Hubble Space Telescope (HST) GO-13297 program “HST Legacy Survey of Galactic Globular Clusters: Shedding UV Light on Their Populations and Formation” have investigated the photometric properties of a large sample of Galactic globular clusters and revolutionized our understanding of their stellar populations. In this paper, we expand upon previous studies by focusing our attention on the stellar clusters’ internal kinematics. We computed proper motions for stars in 56 globular clusters and one open cluster by combining the GO-13297 images with archival HST data. The astrophotometric catalogs released with this paper represent the most complete and homogeneous collection of proper motions of stars in the cores of stellar clusters to date, and expand the information provided by the current (and future) Gaia data releases to much fainter stars and into the crowded central regions. We also census the general kinematic properties of stellar clusters by computing the velocity dispersion and anisotropy radial profiles of their bright members. We study the dependence on concentration and relaxation time, and derive dynamical distances. Finally, we present an in-depth kinematic analysis of the globular cluster NGC 5904.
Journal Article
Diffuse Radio Emission from Galaxy Clusters
In a growing number of galaxy clusters diffuse extended radio sources have been found. These sources are not directly associated with individual cluster galaxies. The radio emission reveal the presence of cosmic rays and magnetic fields in the intracluster medium (ICM). We classify diffuse cluster radio sources into radio halos, cluster radio shocks (relics), and revived AGN fossil plasma sources. Radio halo sources can be further divided into giant halos, mini-halos, and possible “intermediate” sources. Halos are generally positioned at cluster center and their brightness approximately follows the distribution of the thermal ICM. Cluster radio shocks (relics) are polarized sources mostly found in the cluster’s periphery. They trace merger induced shock waves. Revived fossil plasma sources are characterized by their radio steep-spectra and often irregular morphologies. In this review we give an overview of the properties of diffuse cluster radio sources, with an emphasis on recent observational results. We discuss the resulting implications for the underlying physical acceleration processes that operate in the ICM, the role of relativistic fossil plasma, and the properties of ICM shocks and magnetic fields. We also compile an updated list of diffuse cluster radio sources which will be available on-line (
http://galaxyclusters.com
). We end this review with a discussion on the detection of diffuse radio emission from the cosmic web.
Journal Article
Spectroscopic Confirmation of a Protocluster at z = 3.37 with a High Fraction of Quiescent Galaxies
We report the discovery of MAGAZ3NE J095924+022537, a spectroscopically confirmed protocluster at z=3.3665−0.0012+0.0009 around a spectroscopically confirmed UVJ-quiescent ultramassive galaxy (UMG; M⋆=2.34−0.34+0.23×1011M⊙ ) in the COSMOS UltraVISTA field. We present a total of 38 protocluster members (14 spectroscopic and 24 photometric), including the UMG. Notably, and in marked contrast to protoclusters previously reported at this epoch that have been found to contain predominantly star-forming members, we measure an elevated fraction of quiescent galaxies relative to the coeval field ( 73.3−16.9+26.7% versus 11.6−4.9+7.1% for galaxies with stellar mass M ⋆ ≥ 1011 M ⊙). This high quenched fraction provides a striking and important counterexample to the seeming ubiquitousness of star-forming galaxies in protoclusters at z > 2 and suggests, rather, that protoclusters exist in a diversity of evolutionary states in the early universe. We discuss the possibility that we might be observing either “early mass quenching” or nonclassical “environmental quenching.” We also present the discovery of MAGAZ3NE J100028+023349, a second spectroscopically confirmed protocluster, at a very similar redshift of z=3.3801−0.0281+0.0213 . We present a total of 20 protocluster members, 12 of which are photometric and eight spectroscopic including a poststarburst UMG ( M⋆=2.95−0.20+0.21×1011M⊙ ). Protoclusters MAGAZ3NE J0959 and MAGAZ3NE J1000 are separated by 18′ on the sky (35 comoving Mpc), in good agreement with predictions from simulations for the size of “Coma”-type cluster progenitors at this epoch. It is highly likely that the two UMGs are the progenitors of Brightest Cluster Galaxies seen in massive virialized clusters at lower redshift.
Journal Article
PHANGS-HST Catalogs for ∼100,000 Star Clusters and Compact Associations in 38 Galaxies. II. Physical Properties from Decision-tree-based Spectral Energy Distribution Fitting of NUV-U-B-V-I Photometry with Categorical Priors Set by Hα Emission, Cluster Morphology, and Other Auxiliary Information
This paper is the second in a series presenting the catalogs and properties of the largest sample to date of ∼100,000 star clusters and compact associations, in 38 spiral galaxies observed by the PHANGS-HST Treasury survey. Here, we present spectral energy distribution (SED) fitting techniques used to compute the age, mass, and reddening for each object. Our decision-tree-based strategy incorporates categorical priors on model age, reddening, and metallicity determined from additional observed parameters: localized Hα emission, source morphology, and demographic-specific locations in the UBVI color–color diagram. This approach is implemented to mitigate model degeneracies, particularly between young dusty clusters and old clusters with minimal dust, which can have identical optical colors. Results based on Hα narrowband imaging from the ground and from Hubble Space Telescope are intercompared, and contrasted with previous SED-fitting efforts. The fraction of the population that is subject to such priors is ∼14%, and of this subset, ∼63% of old globular clusters (GCs) have ages that change by a factor of 10 or more relative to unconstrained fits with single metallicity (Z⊙) simple stellar population models. The demographics of the population are examined through age–mass and age–reddening diagrams (for individual galaxies as well as aggregated over the sample), and the GC mass function. We demonstrate relationships between cluster age–mass diagrams and properties of parent galaxies (galaxy morphology and location relative to the galaxy main sequence). We outline continuing efforts to improve the inference of physical properties, including the incorporation of JWST infrared photometry and updated synthesis models.
Journal Article