Active galaxies give off bright radiation from their cores, where gas heats up as it is compressed into a swirling accretion disk encircling the black hole.
The file is typically in a compressed format—specifically, the file grows and shrinks with the contents of the VMI and is not defined by the capacity of the VM's hard disk.
这个文件通常采用压缩格式 — 尤其是，该文件并不是根据 VM 的硬盘容量确定的，它的大小随着 VMI 的内容变化。