Ubiquitous cold and massive filaments in cool core clusters
Ubiquitous cold and massive filaments in cool core clusters
复制标题
DOI：
10.1051/0004-6361/201935350
复制
发表时间：
2019-02
影响因子：
6.5
通讯作者：
V. Olivares;P. Salom'e;F. Combes;S. Hamer;P. Guillard;M. Lehnert;F. Polles;R. Beckmann;Y. Dubois;M. Donahue;A. Edge;A. Fabian;B. McNamara;T. Rose;H. Russell;G. Tremblay;A. Vantyghem;R. Canning;G. Ferland;B. Godard;M. Hogan;S. Peirani;G. Forêts
中科院分区：
文献类型：
--
作者：
V. Olivares;P. Salom'e;F. Combes;S. Hamer;P. Guillard;M. Lehnert;F. Polles;R. Beckmann;Y. Dubois;M. Donahue;A. Edge;A. Fabian;B. McNamara;T. Rose;H. Russell;G. Tremblay;A. Vantyghem;R. Canning;G. Ferland;B. Godard;M. Hogan;S. Peirani;G. Forêts
围绕最亮星系团星系(BCG)的多相丝状结构可能是活动星系核反馈的关键步骤。我们观测了半人马座、Abell S1101和RXJ1539.5三个冷星系团核心中的分子气体，并收集了其他12个星系团的ALMA(阿塔卡马大毫米/亚毫米阵列)和MUSE(多单元光谱探测器)数据。这些观测显示出成团的、巨大的和长的(3−25kpc)分子细丝，优先位于由活动星系核膨胀的射电气泡周围。有两个物体显示了核分子盘。光学星云肯定是在追踪冷分子细丝的温暖包层。令人惊讶的是，对于大多数天体，Hα/CO通量比的径向分布大致是恒定的，这表明(I)可能存在1.2至6倍的冷气，(Ii)局部过程肯定是激发的原因。S−1的投影速度在100千米到400千米之间，运动学上有扰动，有时还会有连贯的梯度。这很可能是由于几根尚未分解的细丝混合在一起形成的。速度场可能被气泡、射流或合并引起的晃动引起的湍流搅动。速度和分散度都很低，低于逃逸速度。冷云最终应该会回落，并为AGN提供燃料。我们将细丝的径向范围RFIL与X射线气体可能变得热不稳定的区域进行比较。灯丝总是在低熵和短冷却时间区域内，tCool/tff<；20(13个源中的9个)。在RFIL，TCool/Tff的范围为8−23，可能是由于(I)更复杂的引力势影响自由落体时间Tff(晃动、合并等)。(Ii)ICM中存在不均匀或抬升的气体，影响冷却时间。对于某些源，rFIL位于冷却时间与涡旋周转时间之比tCool/teddy近似为1的位置。
Multi-phase filamentary structures around brightest cluster galaxies (BCG) are likely a key step of AGN-feedback. We observed molecular gas in three cool cluster cores, namely Centaurus, Abell S1101, and RXJ1539.5, and gathered ALMA (Atacama Large Millimeter/submillimeter Array) and MUSE (Multi Unit Spectroscopic Explorer) data for 12 other clusters. Those observations show clumpy, massive, and long (3−25 kpc) molecular filaments, preferentially located around the radio bubbles inflated by the AGN. Two objects show nuclear molecular disks. The optical nebula is certainly tracing the warm envelopes of cold molecular filaments. Surprisingly, the radial profile of the Hα/CO flux ratio is roughly constant for most of the objects, suggesting that (i) between 1.2 and 6 times more cold gas could be present and (ii) local processes must be responsible for the excitation. Projected velocities are between 100 and 400 km s−1, with disturbed kinematics and sometimes coherent gradients. This is likely due to the mixing in projection of several thin (and as yet) unresolved filaments. The velocity fields may be stirred by turbulence induced by bubbles, jets, or merger-induced sloshing. Velocity and dispersions are low, below the escape velocity. Cold clouds should eventually fall back and fuel the AGN. We compare the radial extent of the filaments, rfil, with the region where the X-ray gas can become thermally unstable. The filaments are always inside the low-entropy and short-cooling-time region, where tcool/tff < 20 (9 of 13 sources). The range of tcool/tff of 8−23 at rfil, is likely due to (i) a more complex gravitational potential affecting the free-fall time tff (sloshing, mergers, etc.) and (ii) the presence of inhomogeneities or uplifted gas in the ICM, affecting the cooling time tcool. For some of the sources, rfil lies where the ratio of the cooling time to the eddy-turnover time, tcool/teddy, is approximately unity.