2025/8/15xkong@1第六章

河外星系研究歷史星系分類

星系測量特殊星系星系團

星系演化/~xkong/introast2025/8/15xkong@2星系的形成和演化Howthendidthosedifferentgalaxiescomeintobeing?Doweunderstandgalaxyformationaswellasstarformation?Theanswerisno!

2025/8/15xkong@3星系的形成和演化Why?galaxiesaremuchmorecomplexthanstarstheyarehardertoobserve(z~6.93)theobservationsarehardertointerpret.whereasstarsalmostnevercollidewithoneanother,galaxiesmaysuffermanycollisionsandmergersduringtheirlives,makingitmuchhardertodeciphertheirpasts.

2025/8/15xkong@4Howdidgalaxiesform?2025/8/15xkong@5Ourbestmodelsforgalaxyformationassume:MatteroriginallyfilledallofspacealmostuniformlyGravityofdenserregionspulledinsurroundingmatter2025/8/15xkong@6Denserregionscontracted,formingprotogalacticcloudsHandHegasesinthesecloudsformedthefirststars2025/8/15xkong@7SupernovaexplosionsfromfirststarskeptmuchofthegasfromformingstarsLeftovergassettledintospinningdiskConservationofangularmomentum2025/8/15xkong@8Butwhydosomegalaxiesenduplookingsodifferent?M87NGC44142025/8/15xkong@9

HowdidtheHubblesequenceofgalaxymorphologiesform?

Howdogalaxiesinteractwiththeirenvironment?

WhataretheglobalhistoriesofSF,metalenrichment,andgasconsumption?

Whatistherelationshipbetweenactivegalacticnucleiandtheirhostgalaxies?z=1000z=0Formationofgalaxies?2025/8/15xkong@10HowdidtheHubblesequenceofgalaxymorphologiesform?2025/8/15xkong@112025/8/15xkong@12Howdogalaxiesinteractwiththeirenvironment?10^5galaxieswithredshift10^7In20082025/8/15xkong@13兩種模型2025/8/15xkong@14自下而上（bottom-up）模型較小的(~106M⊙)、不規(guī)則星系首先形成

星系合并形成較大的(~109-1011M⊙)星系在引力的作用下聚集成星系團和超星系團，產(chǎn)生星系團間的巨洞

2025/8/15xkong@15觀測證據(jù):Hubble空間望遠鏡的深場觀測發(fā)現(xiàn)位于2000Mpc距離之外存在大量的不規(guī)則的小星系（超過同類星系在近距離星系中的比例）。2025/8/15xkong@16原始氣體的坍縮首先產(chǎn)生巨大的(~1014M⊙)、薄餅狀的云塊(超星系團)。

云塊分裂成星系團和星系。

由上而下

模型（top-down）2025/8/15xkong@172025/8/15xkong@182025/8/15xkong@19Deepobservationsshowusverydistantgalaxiesastheyweremuchearlierintime(Oldlightfromyounggalaxies)2025/8/15xkong@202025/8/15xkong@21Kongetal.2006,20072025/8/15xkong@222025/8/15xkong@232025/8/15xkong@24BzK-15504VLT-SINFONI自適應(yīng)光學BzK-15504isagaint