Marijana Smailagić, Jason Xavier Prochaska, Joseph Burchett, Guangtun Zhu
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引用次数: 0
Abstract
Abstract We study ultraviolet H i and metal-line transitions in the circumgalactic medium (CGM) of 15 massive, quenched luminous red galaxies (LRGs) at redshift z ∼ 0.5 and with impact parameters up to 400 kpc. We selected eight LRG–CGM systems to study general properties of the CGM around LRGs, while the other seven are already known to contain cool CGM gas from Mg ii optical studies (Mg ii -LRGs). In the general LRG population, we detect H i in four of eight LRGs, in all cases with N H I < 10 16.7 cm −2 . In contrast, all Mg ii -LRGs show H i ; for four LRGs, the H i column density is N H I ≳ 10 18 cm −2 . The CGM of LRGs also shows low and intermediate ionized lines (such as C iii , C ii , Si iii , and Si ii ) and highly ionized lines of O vi (we detect O vi around five of seven Mg ii -LRGs and one of eight in the random sample). Next, we combine our sample with literature LRGs and ≲ L * galaxies, and we find that while for ≲ L * galaxies CGM H i Ly α absorption is stronger as galaxies are more massive, the cool CGM traced by H i Ly α is suppressed above stellar masses of M * ∼ 10 11.5 M ☉ . While most LRG–CGM systems show weak or nondetectable O vi (equivalent width < 0.2 Å), a few LRG–CGM systems show strong O vi 1031, which in most cases likely originates from groups containing both an LRG and a blue star-forming neighboring galaxy.
摘要研究了15个大质量、淬灭红星系(LRGs)在红移z ~ 0.5、冲击参数高达400kpc的环星系介质(CGM)中的紫外H和金属谱线跃迁。我们选择了8个LRG-CGM系统来研究LRGs周围CGM的一般性质,而其他7个已经从Mg ii光学研究中已知含有冷CGM气体(Mg ii -LRGs)。在一般LRG人群中,我们在8个LRG中检测到4个i,在所有的nh i <病例中;10 16.7 cm−2。相反,所有Mg ii -LRGs均显示H i;对于4个LRGs, H i柱密度为N H i > 10 18 cm−2。LRGs的CGM也显示出低和中等电离谱线(如C iii、C ii、Si iii和Si ii)和O vi的高电离谱线(我们在7个Mg ii -LRGs中检测到5个O vi,在随机样本中检测到8个O vi)。接下来,我们将我们的样本与文献LRGs和> L *星系结合起来,我们发现对于> L *星系,随着星系质量的增加,CGM H i Ly α的吸收更强,而H i Ly α追踪到的冷CGM在恒星质量M * ~ 10 11.5 M☉以上被抑制。虽然大多数LRG-CGM系统显示弱或不可检测的O vi(等效宽度<0.2 Å),一些LRG - cgm系统显示出强烈的O vi 1031,在大多数情况下,它可能来自包含LRG和蓝色恒星形成邻近星系的星系群。
期刊介绍:
The Astrophysical Journal is the foremost research journal in the world devoted to recent developments, discoveries, and theories in astronomy and astrophysics.