ALMA Images of the Host Cloud of the Intermediate-mass Black Hole Candidate CO-0.40-0.22∗: No Evidence for Cloud-Black Hole Interaction, but Evidence for a Cloud-Cloud Collision

研究成果: Article査読

13 被引用数 (Scopus)

抄録

This paper reports a reanalysis of archival ALMA data of the high velocity(-width) compact cloud CO-0.40-0.22, which has recently been hypothesized to host an intermediate-mass black hole (IMBH). If beam-smearing effects, difference in beam sizes among frequency bands, and Doppler shift due to the motion of the Earth are considered accurately, none of the features reported as evidence for an IMBH in previous studies are confirmed in the reanalyzed ALMA images. Instead, through analysis of the position-velocity structure of the HCN J = 3-2 data cube, we have found kinematics typical of a cloud-cloud collision (CCC), namely, two distinct velocity components bridged by broad emission features with elevated temperatures and/or densities. One velocity component has a straight filamentary shape with approximately constant centroid velocities along its length but with a steep, V-shaped velocity gradient across its width. This contradicts the IMBH scenario but is consistent with a collision between two dissimilar-sized clouds. From a non-LTE analysis of the multitransition methanol lines, the volume density of the post-shock gas has been measured to be 106 cm-3, indicating that the CCC shock can compress gas in a short timescale to densities typical of star-forming regions. Evidence for star formation has not been found, possibly because the cloud is in an early phase of CCC-triggered star formation or because the collision is nonproductive.

本文言語English
論文番号86
ジャーナルAstrophysical Journal
859
2
DOI
出版ステータスPublished - 2018 6月 1

ASJC Scopus subject areas

  • 天文学と天体物理学
  • 宇宙惑星科学

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