Evolution of the Blue Luminosity-to-Baryon Mass Ratio of Clusters of Galaxies

[摘要] Wederivetheratioofthetotalblueluminositytothetotalbaryonmass,LB/Mb,formassive(MgasattheAbellradiusis≥1×1013h−2.5M⊙)clustersofgalaxiesuptoz≃1fromtheliterature.Twenty-twoclustersinoursampleareatzgt;0.1.Assumingthattherelativemixofhotgasandgalaxiesinclustersdoesnotchangeduringclusterevolution,weuseLB/Mbtoprobethestar-formationhistoryofthegalaxypopulationasawholeinclusters.WefindthatLB/MbofclustersincreaseswithredshiftfromLB/Mb=0.024(LB/M)⊙atz=0to≃0.06(LB/M)⊙atz=1,indicatingafactorof2–3brightening(weassumeH0=70kms−1Mpc−1).ThisamountofbrighteningisalmostidenticaltothebrighteningoftheM/LBratioofearly-typegalaxiesinclustersat0.02≤z≤0.83reportedbyvanDokkumetal.(1998,AAA70.160.065).WecomparetheobservedbrighteningofLB/Mbwithluminosityevolutionmodelsforthegalaxypopulationasawhole,changingthee-foldingtimeofstarformation,Ï„,by0.1≤τ≤5Gyrandtheformationredshift,zF,by2≤zFlt;∞.WefindthatÏ„=0.1Gyrfor‘singleburst’modelswithzF≥3andÏ„=5Gyrfor‘disk’modelswitharbitraryzFareconsistentwiththeobservedbrightening,whilemodelswithÏ„=1–2Gyrtendtopredictbrighteningthatistoosteep.Wealsoderivetheratiooftheblueluminositydensitytothebaryondensityforfieldgalaxies,adoptingΩbh2=0.02,andfindthattheblueluminosityperunitbaryonissimilarinclustersandinfieldsuptoz≃1withintheobservationaluncertainties.

[学科分类] 天文学(综合)

[关键词] "galaxies: clusters: general";"galaxies: evolution";"galaxies: photometry"