Optical emission lines in the most massive galaxies: Morphology, kinematics, and ionisation properties
Optical emission lines in the most massive galaxies: Morphology, kinematics, and ionisation properties
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DOI：
10.1051/0004-6361/202039443
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发表时间：
2020-12
影响因子：
6.5
通讯作者：
I. Pagotto;D. Krajnović;M. den Brok;E. Emsellem;J. Brinchmann;P. Weilbacher;W. Kollatschny;M. Steinmetz
中科院分区：
文献类型：
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作者：
I. Pagotto;D. Krajnović;M. den Brok;E. Emsellem;J. Brinchmann;P. Weilbacher;W. Kollatschny;M. Steinmetz
为了更好地表征星系恒星质量范围的上端，MUSE最大质量星系（M3G）调查的目标是在z ~ 0.046最密集的已知星系团中发现的最大质量星系（M > 1012 M⊙）。该样本由25个早期型星系组成：14个最亮的星系团（bcg），其中3个位于Shapley超级星系团（SSC）最密集的区域，以及11个位于SSC的大质量卫星。在本工作中，我们利用MUSE数据推导了气体的空间分布和运动学，并讨论了其在光学波长范围内的电离机制和起源。我们使用一个广泛的单恒星人口模型库来拟合光谱的连续体，并使用多达三个高斯函数来模拟发射线。在M3G样本中，在5个bgs中检测到电离气体，其中1个位于SSC密度最大的区域，另外6个位于SSC的大质量卫星。在这些天体中，[O I]和[N I]在3个bgs和1颗卫星中被探测到。这种气体几乎集中在所有物体的中心，除了两个显示出细丝的bcg和两个大量发射的卫星。此外，三颗BCGs的发射谱线分布存在红移和/或蓝移成分。通过分析巴尔默线比值，发现尘埃的存在，平均E（B−V）为0.2-0.3。发射线诊断图主要显示低电离核发射线区域线比，几乎没有恒星形成的污染。在M3G样品中，80%的快速旋转器和35%的慢速旋转器中检测到气体。对于60%的卫星和25%的bgs来说，恒星和气体的旋转方向是相互一致的。偏差的存在表明，三颗BCGs和两颗卫星的气体来自外部。另一方面，其中一些系统的特征是三轴和长轴状的恒星旋转，即使在不对准的情况下，这也可以支持气体的内部起源。
In order to better characterise the upper end of the galaxy stellar mass range, the MUSE Most Massive Galaxies (M3G) Survey targeted the most massive galaxies (M > 1012 M⊙) found in the densest known clusters of galaxies at z ∼ 0.046. The sample is composed of 25 early-type galaxies: 14 brightest cluster galaxies (BCGs), of which 3 are in the densest region of the Shapley super cluster (SSC), and 11 massive satellites in the SSC. In the present work we use MUSE data to derive the spatial distribution and kinematics of the gas and discuss its ionisation mechanism and origin in the optical wavelength range. We fit the continuum of the spectra using an extensive library of single stellar population models and model the emission lines employing up to three Gaussian functions. In the M3G sample, ionised gas was detected in five BCGs, of which one is in the densest region of the SSC, and six massive satellites in the SSC. Among these objects, [O I] and [N I] were detected in three BCGs and one satellite. The gas is centrally concentrated in almost all objects, except for two BCGs that show filaments and two massive satellites with extended emission. Moreover, the emission line profiles of three BCGs present redshifted and/or blueshifted components. The presence of dust was revealed by analysing Balmer line ratios, obtaining a mean E(B − V) of 0.2–0.3. The emission-line diagnostic diagrams show predominately low-ionisation nuclear emission-line regions line ratios with little contamination from star formation. In the M3G sample, the gas was detected in 80% of fast rotators and 35% of slow rotators. The orientations of stellar and gaseous rotations are aligned with respect to each other for 60% of satellites and 25% of BCGs. The presence of misalignments points to an external origin of the gas for three BCGs and two satellites. On the other hand, some of these systems are characterised by triaxial and prolate-like stellar rotation, which could support an internal origin of the gas even in the case of misalignments.