{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.galaxy-group-or-cluster","code":"thing-q14515149","url":"https://ver.cy/models/thing/q14515149/","name":"galaxy group or cluster","alternateNames":[],"kind":"thing","status":"published","version":"0.2.0-wave.1","language":"en","classifiers":{"family":"Thing Registry","category":"Physical world and living systems","entryKind":"thing","plane":"PHY","domain":["PHY.SPC"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"A gravitationally bound system of galaxies, from small groups of a few to about 50 galaxies, such as the Local Group, to rich clusters with hundreds to thousands of galaxies, such as the Virgo and Coma clusters, embedded in dark matter and hot intracluster gas.","purpose":"Let an agent describe galaxy groups and clusters by name, membership, mass, observations and cosmological use, with sourced data.","scope":{"in":[],"out":[],"boundaries":[]},"distinguishingFeatures":["Gravitationally bound","Dominated by dark matter","Hot intracluster gas","Used as cosmological probes"],"structure":{"bundles":[{"id":"system","name":"System","description":"Which group or cluster.","layers":[{"id":"identity","name":"Identity","description":"Name.","findings":[{"id":"identity-finding","name":"Identity","description":"Identity.","questions":[{"text":"Which group or cluster is meant, and how far away is it?","kind":"provenance"},{"text":"Which catalogue lists it?","kind":"provenance"}]}]},{"id":"members","name":"Members","description":"Galaxies.","findings":[{"id":"members-finding","name":"Members","description":"Members.","questions":[{"text":"How many galaxies does it contain?","kind":"measurement"},{"text":"Which are the brightest members?","kind":"provenance"}]}]}]},{"id":"mass","name":"Mass","description":"Dark matter.","layers":[{"id":"estimate","name":"Estimate","description":"Methods.","findings":[{"id":"estimate-finding","name":"Estimate","description":"Mass estimate.","questions":[{"text":"What is its estimated mass, and by which method?","kind":"measurement"},{"text":"How uncertain is it?","kind":"boundary"}]}]},{"id":"lensing","name":"Lensing","description":"Gravitational lensing.","findings":[{"id":"lensing-finding","name":"Lensing","description":"Lensing.","questions":[{"text":"Does the cluster act as a gravitational lens?","kind":"provenance"},{"text":"What does lensing reveal?","kind":"provenance"}]}]}]},{"id":"gas","name":"Gas","description":"Intracluster medium.","layers":[{"id":"xray","name":"X-ray","description":"Observations.","findings":[{"id":"xray-finding","name":"X-ray","description":"X-ray observations.","questions":[{"text":"What do X-ray observations show about the hot gas?","kind":"provenance"},{"text":"Which telescopes observed it?","kind":"provenance"}]}]},{"id":"mergers","name":"Mergers","description":"Collisions.","findings":[{"id":"mergers-finding","name":"Mergers","description":"Cluster mergers.","questions":[{"text":"Is the cluster merging with another?","kind":"provenance"},{"text":"What evidence shows it?","kind":"provenance"}]}]}]},{"id":"cosmology","name":"Cosmology","description":"Large-scale structure.","layers":[{"id":"probes","name":"Probes","description":"Cluster counts.","findings":[{"id":"probes-finding","name":"Probes","description":"Cosmological probes.","questions":[{"text":"How are cluster counts used to test cosmological models?","kind":"definition"},{"text":"Which surveys provide them?","kind":"provenance"}]}]},{"id":"local","name":"Local Group","description":"Our group.","findings":[{"id":"local-finding","name":"Local Group","description":"Local Group.","questions":[{"text":"Which galaxies belong to the Local Group?","kind":"provenance"},{"text":"What is the future of the Milky Way and Andromeda, according to studies?","kind":"provenance"}]}]}]}]},"agentConduct":{"may":["Report catalogued galaxy groups and clusters with their members, distances and sources.","Present mass and distance estimates with their uncertainties and methods."],"mustNot":["Confuse groups, clusters and superclusters.","Present a mass or distance estimate without its uncertainty.","Merge or split catalogue entries without recording the reason."],"requiresHuman":["Publishing a revised membership or mass estimate as authoritative."]},"ethics":{"considerations":["Clusters underpin estimates of dark matter and cosmology, so errors propagate widely."],"affectedParties":["Astronomers and cosmologists","Students and the interested public"]},"owners":{"steward":"Nobody owns them; astronomical catalogues and the scientific community keep the records.","roles":[],"masterSystems":["Astronomical object databases and cluster catalogues"]},"relations":[{"target":"Q15053549","type":"parent","note":"registry parent class"},{"target":"Q21157127","type":"parent","note":"registry parent class"},{"target":"gravitationally bound system","type":"related","note":"category"},{"target":"galaxy","type":"contains","note":"members"},{"target":"supercluster","type":"related","note":"larger structure"},{"target":"gravitational lensing","type":"related","note":"effect"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.galaxy-group-or-cluster","Wikidata: Q14515149 (https://www.wikidata.org/wiki/Q14515149)","Abell catalogue: Abell numbers cluster catalogue"]},"properties":{"applicability":"required","items":["Total gravitating mass:  solar masses - Mass is inferred from galaxy motions, gravitational lensing or hot gas observations within a stated boundary.","Physical radius:  megaparsecs - Radius is estimated from observations using a specified membership boundary or density threshold.","Galaxy velocity dispersion:  kilometres per second - Velocity dispersion is estimated from the spread of member galaxy line of sight velocities after accounting for measurement uncertainties.","Hot gas temperature:  kelvins - Gas temperature is inferred by fitting thermal emission models to X-ray spectra where detectable hot gas is present."]},"recognition":{"applicability":"required","items":["Many galaxies close together on the sky","X-ray emitting intracluster medium","Superclusters are larger, looser structures","Concentrations of galaxies in telescope images; X-ray glow from hot gas."]},"capabilities":{"applicability":"required","items":["identify groups and clusters and their members","explain dark matter and intracluster gas evidence","describe gravitational lensing by clusters","find survey catalogues"]},"hazards":{"applicability":"required","items":["Confusing groups, clusters and superclusters","Presenting mass estimates without uncertainty"]},"interfaces":{"applicability":"required","items":["Naming of celestial objects, International Astronomical Union."]},"context":{"applicability":"required","items":["Understanding large-scale structure, dark matter and cosmology.","galaxy groups such as the Local Group","rich galaxy clusters","fossil groups","merging clusters"]}},"sources":[{"title":"Wikidata item Q14515149: galaxy group or cluster","url":"https://www.wikidata.org/wiki/Q14515149","note":"identity and sense of the item"},{"title":"Wikipedia: Galaxy groups and clusters","url":"https://en.wikipedia.org/wiki/Galaxy_groups_and_clusters","note":"general description of the item"}],"openQuestions":["Should groups and clusters be separate entries?","How should catalogues be linked?","How should mass estimates be sourced?"],"resources":{"spec":"/models/things/publications/thing-q14515149/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q14515149/spec.json"],"providers":["Claude"],"researchStatus":"unreviewed","generatedAt":"2026-09-11T11:39:17Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"filled","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-07T10:10:26+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass"},"score":1.0}}