Tiny, compact galaxies are masters of camouflage within the distant universe – looking for the secrets behind the little red dots

Astronomers explore the distant universe with the James Webb Space TelescopeNASA's strongest telescope, have discovered a category of galaxies that challenges even probably the most expert creatures to mimic – just like the Imitating an octopus. This creature can impersonate other sea creatures to avoid predators. You should be a flatfish? No problem. A sea serpent? Easy.

When astronomers analyzed the primary Webb images of the distant parts of the universe, they found a never-before-seen group of galaxies. These galaxies – several hundred of them, called Small red dots – are very red and compact and only visible during about 1 billion years of cosmic history. Like the mimic octopus, the small red dots puzzle astronomers because they appear like different astrophysical objects. They are either very massive galaxies or those of medium size, each of which incorporates a supermassive black hole at its core.

One thing is definite, nonetheless. The typical little red dot is small, with a radius of only 2% of them the Milky Way Galaxy. Some are even smaller.

As an astrophysicist As a scientist studying distant galaxies and black holes, I’m interested by understanding the character of those small galaxies. What powers their light and what are they really?

The copycat competition

Astronomers analyze the sunshine our telescopes receive from distant galaxies to find out their physical properties, resembling the variety of stars they contain. We can use the properties of their light to review the little red dots and discover in the event that they are made up of many stars or if there’s a black hole inside them.

The light that reaches our telescopes has a wavelength from long radio waves to high-energy gamma raysAstronomers break down the sunshine into different frequencies and visualize them in a diagram. a so-called spectrum.

Sometimes the spectrum incorporates Emission linesthese are frequency ranges where more intense light emission occurs. In this case, we are able to use the form of the spectrum to predict whether the galaxy hosts a supermassive black hole and estimate its mass.

Likewise, studying the X-ray emission of a galaxy can provide information in regards to the existence of a supermassive black hole.

The ultimate masters of camouflage, the tiny red dots appear as different astrophysical objects depending on whether astronomers are studying them using X-rays, emission lines, or something else.

The information astronomers have gathered up to now from the spectra and emission lines of the small red dots has led to 2 divergent models explaining their nature. These objects are either extremely dense galaxies with billions of stars or a supermassive black hole.

The two hypotheses

In the stars-only hypothesis, the small red dots contain an enormous variety of stars – as much as 100 billion starsThat’s in regards to the same variety of stars as within the Milky Way – a much larger galaxy.

Imagine yourself standing alone in an enormous, empty room. This vast, quiet room represents the region of the universe near our solar system, where the celebs are sparsely scattered. Now imagine the identical room, but full of your entire population of China.

This crowded space is what could be the core of the densest little red dots. These astrophysical objects may very well be the densest stellar environments throughout the universe. Astronomers usually are not even sure whether such star systems can physically exist.

Then there’s the black hole hypothesis. The majority of the small red dots show clear signs of presence from a supermassive black hole at its center. Astronomers can tell whether a black hole is present within the galaxy by taking a look at the big emission lines within the galaxy's spectra. These lines are attributable to the gas swirling across the black hole at high speed.

In fact, astronomers estimate These black holes are too massivein comparison with the dimensions of their compact host galaxies.

Black holes typically have a mass of about 0.1% of the stellar mass of their host galaxies. But a few of these small red dots a black hole of just about the identical mass than their entire galaxy. Astronomers call these black holes supermassive because their existence contradicts the standard ratio normally observed in galaxies.

However, there’s one other catch. Unlike atypical black holes, the atoms presumably present within the small red dots are don’t show Signs of X-ray emission. Even within the deepestHigh-energy images during which astronomers could easily observe these black holes lack any trace of them.

Few solutions and plenty of hopes

So are these astrophysical curiosities massive galaxies with far too many stars? Or do they harbor supermassive black holes at their centers which are too massive and don’t emit enough X-rays? What a mystery.

With further observations and theoretical models, astronomers are step by step coming up with some possible solutions. Perhaps the small red dots are only stars, but these stars are so dense and compact that they imitate The Emission lines that typically from a black hole.

Or perhaps supermassive – even supermassive – black holes lurk on the core of those little red dots. If that is the case, two models can explain the shortage of X-ray emissions.

First, large amounts of gas may very well be floating across the black hole, which block a part of the high-energy radiation ejected from the middle of the black hole. Secondly, the black hole could suck in gas much faster than usual. This process would create a unique spectrum with fewer X-rays than astronomers normally see.

The proven fact that black holes are too big or too massive might not be an issue for our understanding of the universe, but reasonably one of the best clue to how the first black holes within the universe. In fact, the primary black holes that formed were very massive – about 100,000 times the mass of the sun – Theoretical models suggest that their ratio of the mass of the black hole to the mass of the host galaxy could remain high for a very long time after its creation.

So how can astronomers discover the true nature of those tiny points of sunshine that shone initially of time? As within the case of our master of camouflage – the octopus – the key lies in observing their behavior.

With the Webb telescope and more powerful X-ray telescopes Further observations eventually reveal a feature that astronomers can only assign to one in all the 2 scenarios.

For example, if astronomers could clearly detect X-rays, radio waves or infrared light from the vicinity of the possible black hole, they might know that the black hole hypothesis is correct.

Just as our sea friend can pretend to be a starfish, in some unspecified time in the future he’ll move his tentacles and reveal his true nature.