Constraining cold accretion on to supermassive black holes: molecular gas in the cores of eight brightest cluster galaxies revealed by joint CO and CN absorption
Constraining cold accretion on to supermassive black holes: molecular gas in the cores of eight brightest cluster galaxies revealed by joint CO and CN absorption
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DOI：
10.1093/mnras/stz2138
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发表时间：
2019-07
影响因子：
4.8
通讯作者：
T. Rose;A. Edge;F. Combes;M. Gaspari;S. Hamer;N. Nesvadba;A. Peck;C. Sarazin;G. Tremblay;S. Baum;M. Bremer;B. McNamara;C. O’Dea;J. Oonk;H. Russell;P. Salom'e;M. Donahue;A. Fabian;G. Ferland;R. Mittal;A. Vantyghem
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文献类型：
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作者：
T. Rose;A. Edge;F. Combes;M. Gaspari;S. Hamer;N. Nesvadba;A. Peck;C. Sarazin;G. Tremblay;S. Baum;M. Bremer;B. McNamara;C. O’Dea;J. Oonk;H. Russell;P. Salom'e;M. Donahue;A. Fabian;G. Ferland;R. Mittal;A. Vantyghem
为了推进我们对宇宙中最大质量黑洞的燃料和反馈过程的理解，我们需要显着增加我们对存在于其周围环境中的分子气体的知识。然而，由于直接观察它的困难，人们对这种气体的行为知之甚少。我们报告的调查18个最明亮的星系团星系躺在冷的核心，从其中我们检测到分子气体的核心区域的8个通过一氧化碳（CO），氰化物（CN）和一氧化硅（SiO）的吸收线。这些吸收线是由冷分子气体云产生的，这些气体云沿着视线指向星系中心明亮的连续光源。因此，它们可以用来确定分子气体的许多性质，这些性质可能会继续为超大质量黑洞吸积和AGN反馈机制提供燃料。探测到的吸收区相对于星系的系统速度的速度范围为-45 ~283 km s-1，并且偏向于向宿主超大质量黑洞运动。我们发现CN N = 0 − 1的吸收线通常比CO J = 0 − 1的吸收线强10倍。这是由于CN分子具有较高的电偶极矩，从而增强了其吸收强度。在分子数密度方面，CO仍然是更普遍的分子，CO/CN的比例为10/10，与邻近星系相似。CO，CN，和H i观测这些系统的比较表明，这些吸收线的许多不同的组合被检测到。
To advance our understanding of the fuelling and feedback processes which power the Universe’s most massive black holes, we require a significant increase in our knowledge of the molecular gas which exists in their immediate surroundings. However, the behaviour of this gas is poorly understood due to the difficulties associated with observing it directly. We report on a survey of 18 brightest cluster galaxies lying in cool cores, from which we detect molecular gas in the core regions of eight via carbon monoxide (CO), cyanide (CN) and silicon monoxide (SiO) absorption lines. These absorption lines are produced by cold molecular gas clouds which lie along the line of sight to the bright continuum sources at the galaxy centres. As such, they can be used to determine many properties of the molecular gas which may go on to fuel supermassive black hole accretion and AGN feedback mechanisms. The absorption regions detected have velocities ranging from −45 to 283 km s−1 relative to the systemic velocity of the galaxy, and have a bias for motion towards the host supermassive black hole. We find that the CN N = 0 − 1 absorption lines are typically 10 times stronger than those of CO J = 0 − 1. This is due to the higher electric dipole moment of the CN molecule, which enhances its absorption strength. In terms of molecular number density CO remains the more prevalent molecule with a ratio of CO/CN ∼10, similar to that of nearby galaxies. Comparison of CO, CN, and H i observations for these systems shows many different combinations of these absorption lines being detected.