この「円盤風」の2次元マップから、銀河形成の手がかりが見えてくるかもしれません。 The 2D map of this “disk wind” may reveal clues to galaxy formation.
2023-04-10 マサチューセッツ工科大学(MIT)
今回、降着円盤の揺れを利用して、降着円盤の風の2次元マップを初めて作成し、その垂直方向の形や構造、速度が明らかになりました。この結果は、超巨大ブラックホールが銀河全体をどのように形作っているかを知る手がかりになるかもしれません。
＜関連情報＞
- https://news.mit.edu/2023/scientists-map-gusty-winds-neutron-star-system-0410
- https://www.nature.com/articles/s41550-023-01929-7
X線連星における垂直風構造が、歳差降着円盤によって明らかにされる Vertical wind structure in an X-ray binary revealed by a precessing accretion disk
P. Kosec,E. Kara,A. C. Fabian,F. Fürst,C. Pinto,I. Psaradaki,C. S. Reynolds,D. Rogantini,D. J. Walton,R. Ballhausen,C. Canizares,S. Dyda,R. Staubert & J. Wilms
Nature Astronomy Published:10 April 2023
DOI:https://doi.org/10.1038/s41550-023-01929-7
Abstract
The accretion of matter onto black holes and neutron stars often leads to the launching of outflows that can greatly affect the environments surrounding the compact object. An important means of studying these winds is through X-ray absorption line spectroscopy, which allows us to probe their properties along a single sightline, but usually provides little information about the global three-dimensional wind structure, which is vital for understanding the launching mechanism and total wind energy budget. Here, we study Hercules X-1, a nearly edge-on X-ray binary with a warped accretion disk precessing with a period of about 35 d. This disk precession results in changing sightlines towards the neutron star, through the ionized outflow. We perform time-resolved X-ray spectroscopy over the precession phase and detect a strong decrease in the wind column density by three orders of magnitude as our sightline progressively samples the wind at greater heights above the accretion disk. The wind becomes clumpier as it rises upwards and expands away from the neutron star. Modelling the warped disk shape, we create a two-dimensional map of wind properties. This measurement of the vertical structure of an accretion disk wind allows direct comparisons with three-dimensional global simulations to reveal the outflow launching mechanism.
