Radio images of the sky have seen hundreds of ‘baby’ and horrible black holes seen in distant galleries, with gallery light kicking around in unexpected ways.
Galaxies are large cosmic bodies, tens of thousands of light-years in size, made up of gas, dust, and stars (like our sun).
Given their size, you would expect the amount of light emitted from galleries to change slowly and steadily, over long periods of time beyond a person’s life.
But our research, published in the Monthly notices from the Royal Astronomical Society, discovered an amazing population of galaxies whose light changes much faster, in just a few years.
What is a radio galaxy?
Astronomers believe that most galaxies have a supermassive black hole in the center. Some of these are ‘active’, which means they emit a lot of radiation.
Their powerful gravitational fields pull in material from their surroundings and tear it apart in an orbiting donut of hot plasma called a ‘collection disk’.
This disc moves around the black hole at almost the speed of light. Magnetic fields accelerate energized particles from the disk in long thin currents or ‘jets’ on the black hole rotating axes. As they get further from the black hole, these jets grow into large clouds in the shape of mushrooms or ‘lobes’.
It is this whole structure that makes up a radio galaxy, so-called because it emits a lot of radio frequency radiation. It can be hundreds, thousands or even millions of light years over it so it can take aeons to show any amazing changes.
Astronomers have long questioned why some radio galleries host large lobes, while others remain small and limited. There are two theories. One is that the jets are held back by dense material around the black hole, often called frustrated lobes.
However, the details of this phenomenon are not yet known. It is not yet clear whether the lobes are temporarily confined to a slightly dense environment – or if they are slowly pushing through a larger but less dense environment.
The second theory for explaining smaller lobes is that the jets are young and have not yet expanded to great distances.
Hercules Awesome black hole releases huge energy jets into radio lobes. (NASA / ESA / NRAO)
Old ones are red, baby blue
Radio galaxies old and young can be identified using modern day radio astronomy: looking at their ‘radio color’.
We looked at data from the GaLactic and Extragalactic All Sky MWA (GLEAM) study, which sees the skies at 20 different radio frequencies, giving astronauts an unequal ‘radio color’ view of the sky.
From the data, baby radio galaxies appear blue, which means they are brighter at higher radio frequencies. At the same time the dying radio galleries appear red and are brighter in the lowest radio frequencies.
We identified 554 baby radio galaxies. When we look at similar data taken a year later, we were surprised to see that 123 of these were kicking around in their clarity, seemingly blinking. This left us puzzled.
Something more than one light-year-old in magnitude cannot change so much in brightness over less than a year without violating the laws of physics. So either our galleries were much smaller than expected, or something else was happening.
Fortunately, we had the data we needed to find out.
Previous research on the variability of radio galaxies has used either a small number of galaxies, archived data collected from multiple telescopes, or was performed using just one frequency.
For our research, we studied more than 21,000 galaxies over one year over radio frequencies. This makes it the first study of ‘celestial variability’, allowing us to see how galaxies change brightness at different frequencies.
Some of our kicking baby radio galleries have changed over the years we suspect they are kids kicks at all. Chances are that those tight radio galleries of angsty teens are fast becoming adults much faster than we expected.
While most of our variable galaxies increased or decreased in brightness by nearly the same amount across all radio colors, some did not. Also, 51 galaxies changed in both resolutions and color, which may be an idea of what is causing the variability.
Artist’s impression of SKA-middle (left) and SKA-lower (right) telescopes. (SKAO / ICRAR / SARAO)
Three opportunities for what’s happening
1) Connecting galaxies
As light from stars travels through the Earth’s atmosphere, it is inverted. This creates the twinkling effect of the stars we see in the night sky, known as ‘scintillation’. The light from the radio galleries in this study went through our Milky Way galaxy to reach our telescopes on Earth.
Thus, the gas and dust inside our galaxy could be separated in the same way, resulting in a twinkling effect.
2) Looking down on the barrel
In our three-dimensional Universe, black holes sometimes burn high-energy particles directly to us on Earth. These radio galleries are called ‘blazars’.
Instead of seeing long thin jets and large mushroom-shaped lobes, we see blazars as a tiny dot. They can make a big difference in short timeframes, as any small dash from the horrible black hole itself is directed directly at us.
3) Black hole
When the supermassive black hole in the middle awakens some extra grains they form a lump traveling slowly on the jets. As the clump moves out, we can find it first in the ‘radio blue’ and then later in the ‘radio red’.
So maybe we find large black hole lumps traveling slowly through space.
Where now?
This is the first time we have demonstrated the ability of high-variability analysis technology across multiple radio colors. The results show that we lack an understanding of the radio space and that radio galleries are perhaps more vibrant than we expected.
As the next generation of telescopes comes online, most notably the Square Kilometer Array (SKA), astronauts will build a dynamic picture of the skies over several years.
In the meantime, it’s worth watching these weird radio galleries and keeping a close eye on the kicking babies as well. 
Kathryn Ross, PhD Student, Curtin University and Natasha Hurley-Walker, Radio Astronomer, Curtin University.
This article is republished from The Conversation under a Creative Commons license. Read the original article.