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.
Orienting Eddington
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.
Calling the Question
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.
A Question of Quasars
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.
Missing Ingredient
There’s been a bit of press regarding “missing light” in the universe. It all starts with a recent paper in the Astrophysical Journal Letters. Most of the popular articles spin things as missing light because that was the spin of the press release, but the actual work is more subtle, and more interesting.
Mini Me
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.
Seeing Red
Ever since Henrietta Leavitt discovered the period-luminosity relation for Cepheid variable stars, and Edwin Hubble used her work to demonstrate the relation between the redshifts of galaxies and their distances, we’ve had a pretty good idea that the universe was expanding. Since then we’ve gathered much more evidence on the connection between redshift and cosmic expansion, including redshift observations of distant supernovae that show the universe is undergoing cosmic inflation due to dark energy. While cosmic expansion is now well established, there have been some interesting mysteries along the way. One of these involves some seemingly strange behavior of quasars.
Turn, Turn, Turn
Quasars are supermassive black holes that are very far away. This means the study of quasars allow us to understand the earliest examples of active black holes, but it also means they can be difficult to observe. But for one quasar, its location behind a closer galaxy allows us to better determine its properties. In particular we now know it rotates very quickly.
Unlimited
In 1916, Eddington demonstrated that there was a limit to how bright a stable star could be, known as the Eddington limit. Now a new paper shows that black holes can generate more energy than that limit would imply.