Constraining accretion and relativistic jet physics with multi-wavelength observations of accreting compact objects

白矮星、中子星和黑洞是宇宙中最极端的物体。在这些密集的物体中，类似太阳的质量可以集中在地球大小（白矮星），城市大小（中子星）或无限小点（黑洞）的物体中。尽管这些致密天体具有奇异的性质，但它们也是宇宙中各种尺度、吸积盘和准直喷流反复出现的过程的家园。吸积盘是围绕中心物体的结构，在那里物质流向中心物体。在某些情况下，物质可能会以射流的形式流出，可能垂直于圆盘。这种过程的结合在各种各样的天体上都可以看到：行星形成的圆盘聚集在年轻的恒星上，并可以产生喷流；围绕白矮星、中子星和恒星质量黑洞运行的恒星的外层物质吸积到致密的物体上，并形成接近光速的物质射流（相对论性射流）；星系中心的物质可以吸积到超大质量黑洞上，也会产生相对论性喷流。尽管吸积物理和喷流形成具有普遍的性质，但仍有许多悬而未决的问题。相对论性喷流也非常重要，因为它们会对周围环境产生重大影响。天文学家目前认为，超大质量黑洞的相对论性喷流可能在星系形成过程中发挥了重要作用。

White dwarfs, neutron stars, and black holes are some of the most extreme objects in the Universe. In these dense objects, a mass similar to that of the Sun can be concentrated in objects the size of the Earth (white dwarfs), the size of a city (neutron stars), or an infinitesimal point (black holes). Despite their exotic nature, these compact objects are also home to processes that appears repeatedly in the Universe over a variety of scales, accretion discs and collimated outflows of jets. Accretion discs are structures around central objects where material flows onto the central object. In some cases, material may manage to flow out, presumably perpendicular to the disc, in jets. This combination of processes is seen across a wide variety of astronomical objects: the discs from which planets form accrete onto young stars and can produce jets; material from the outer envelopes of stars orbiting around white dwarfs, neutron stars, and stellar-mass black holes accrete onto the compact objects and jets of material flowing near the speed of light (relativistic jets) can form; and material at the center of galaxies can accrete onto supermassive black holes, also producing relativistic jets. Despite the universal nature of accretion physics and jet formation, there are many open questions. Relativistic jets are also extremely important as they can significantly impact their environment. Astronomers currently believe that the relativistic jets from supermassive black holes may play an important role in how galaxies form.