鄰近宇宙中哈伯序列星系性質與周邊環境密度相關性之系統性研究

Abstract

我們對幾個關鍵銀河特性（如大小、顏色、D4000、恆星形成率）在環境中的相關性進行了系統性研究，這些研究分別針對橢圓星系、透鏡星系、早期和晚期盤狀星系。我們使用來自史隆數位巡天（SDSS）的低紅移體積限制星系樣本，發現這些相關性雖然隨著哈勃序列系統地變化，但通常相對較弱。我們進一步使用由宇宙學流體力學模擬 IllustrisTNG 生成的星系樣本來檢查這些相關性，發現總體上有很好的吻合，尤其是對於中央星系。我們的結果表明，無論哪些機制負責塑造星系的形態，它們必須在高紅移時期就已經發生，以至於到紅移接近0時，環境相關性幾乎已經被沖淡。

We have conducted a systematic study of the dependencies on environments of several key galactic properties (such as size, color, 4000 Angstrom break strength, star formation rate) for elliptical, lenticular, early and late-type disk galaxies separately, using a low redshift volume-limited galaxy sample constructed from the Sloan Digital Sky Survey (SDSS), finding that the dependencies, albeit varying systematically with the Hubble sequence, are typically rather weak. We have further examined such dependencies using galaxies produced by the cosmological hydrodynamical simulation IllustrisTNG, finding generally good agreements, especially for central galaxies. Our results suggest that, whatever mechanisms that are responsible for shaping the morphology of galaxies must have taken place at high-$z$ such that by z~0, environmental dependencies are nearly washed out.