How do we determine the size of a quasar billions of light years away? We observe the rate at which they vary in brightness.
A cluster of four quasars with a million light years of each other has been found, and we aren’t quite sure how such a cluster could have formed.
Eight galaxies have been found with emission nebula much brighter than the central quasar, and might be due to binary black holes from a galactic merger.
Radio astronomy is so precise that by observing quasars we can measure not only changes in Earth’s rotation, but also tectonic drift between radio telescopes.
There’s been press recently that astronomers have discovered a “spooky” or “mysterious” alignment of quasars across the universe. While such claims make great headlines, the new results aren’t spooky at all, nor are they that mysterious. They are somewhat interesting, so it’s worth discussing.
Quasars are among the most energetic things in the universe, and are intense sources of radio waves and visible light. Because of their great distance, they appeared almost point-like to early observers. Thus they were given the name quasi-stellar radio sources, or quasars for short. For several decades the source of their great power was a mystery, but we know know that they are powered by active supermassive black holes in the centers of galaxies. As we’ve observed more quasars, we’ve found that they can vary significantly in brightness, redshift, and line spectra.
A couple days ago I wrote about a rather large cluster of quasars, and how it seemed to be larger than we’d expect for the universe as we know it. The post gathered the attention of an anonymous commenter, who pointed out an opposing view regarding this research. The rebuttal to the cluster research was published in MNRAS, and makes a rather simple claim: not all patterns are real. In other words, if you look deep enough for a pattern in your data, you are bound to find one, even if it is really just noise.
Quasars are intense sources of radio energy that appear as almost starlike points. For this reason, when they were first discovered in 1939 they came to be known as quasi-stellar radio sources, or quasars for short. Early on it was not entirely clear what these objects were. They were incredibly energetic, and they also tended to have very large redshifts, which implied that they were very far away. It was also noticed that quasars weren’t randomly scattered across the sky, but instead tended to clump together in groups.
Because microquasars are physically similar to regular quasars, with a compact massive core, accretion disk and jets, the dynamics of the two are likewise similar. But since the microquasar is stellar mass rather than a million solar masses, the timescale of a microquasar is much smaller. This means we can watch a system change over days rather than centuries.
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