跳舞的幽灵：活跃星系的弯曲喷流

2021年9月1日

Dancing Ghosts: Curved Jets from Active Galaxies
Image Credit: Jayanne English & Ray Norris, EMU-ASKAP, DES; Text: Jayanne English (U. Manitoba)

Explanation: Why would galaxies emit jets that look like ghosts? And furthermore, why do they appear to be dancing? The curled and fluffy jets from the supermassive black holes at the centers of two host galaxies (top center and lower left) are unlike anything seen before. They were found by astronomers using the Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope when creating maps tracing the evolution of galaxies. Images preceding this Evolutionary Map of the Universe survey only showed amorphous blobs. Eventually, comparisons of relative amounts of energy emitted revealed the glowing elongated structures were created by electrons streaming around magnetic field lines. Overlaying the radio data on an optical view of the sky (Dark Energy Survey) confirmed that the electron streams originated from the centers of active galaxies. Usually such Active Galactic Nuclei (AGN) produce straight jets. A leading hypothesis for the geometric origin of these unusually graceful shapes involves the flow of large-scale intergalactic winds.

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Tomorrow’s picture: Messier’s 51st

跳舞的幽灵：活跃星系的弯曲喷流
影像提供: Jayanne English & Ray Norris, EMU-ASKAP, DES; 文稿: Jayanne English (U. Manitoba)

说明: 为何星系射出的喷流形似幽灵？此外，为何它们看似在跳舞？源自影像中心这二个寄主星系的超大质量黑洞（顶缘及左下）、外观弯曲蓬松的喷流，是前所未见的景观。它们是天文学家使用澳洲探路者平方公里阵列（ASKAP），在制作星系演化示迹图时所发现的。在这幅巡天演化图之前所拍摄的影像，只见到2团无定形的斑块。后来比较它们辐射出的能量之高低，才意识到这些长形的结构，是来自沿着磁力线回旋流动的电子。叠合电波数据及暗能量巡天的可见光影像之后，证实这些电子流的源头是活跃星系的核心。只不过，活跃星系核（AGN）射出的通常是笔直的喷流。诠释这些奇特几何形状的最可信假说认为，这些喷流不寻常的弯曲形状，与泛流的大尺度星系际风有关。

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明日的图片: Messier’s 51st