Unlocking the Universe: How Cosmic Infrared Radiation Mapping Will Reveal the Secrets of Galaxies from the Big Bang to Today

Cosmic infrared radiation gives us a picture of everything that has happened in the universe from a few hundred thousand years after the Big Bang until now. But dust in our own solar system scatters light at the same wavelengths and distorts the image.

Now the researchers will use historical data from several different telescopes to get a clear picture of what is dust and what is radiation from space outside our own galaxy.

– Our main goal is to create maps of the infrared galaxies in the entire universe, from the first galaxies to the present day, says researcher Duncan Watts at the Department of Astronomy Theoretical UiO.

With maps showing the cosmic background radiation, researchers will be able to find out when and where the galaxies were formed, and what the physical processes are behind them. But the research will also contribute to knowledge about our own local galaxy, the Milky Way, and our own solar system.

– To create these maps, we map the interplanetary dust cloud that surrounds our solar system. It includes understanding how asteroids, comets and other small objects contribute to this radiation, says Watts.

Radiation from the beginning of time

Infrared radiation, or infrared light, is electromagnetic radiation with wavelengths between 0.7 micrometers and 1 millimeter. While the stars we see in the sky are so hot that they emit visible, high-frequency white light, objects at lower temperatures emit infrared light , invisible.

Today, 13.7 billion years after the birth of the universe and The Big Bang, space is full of cold dust that emits such infrared light. This is dust from the creation of stars and galaxies from the beginning of time to the present day. Watts compares it to the dim light from the remains of a smoldering fire. Cosmologists call it CIB – cosmic infrared background light.

– If we look at the big picture, we can still see the light from the big bang. Immediately after the big bang, the universe was so tightly packed together that light could not escape, but after about 300,000 years the universe had expanded enough for light to escape, Watts explained.

Since then, this light has continued to spread through space. As time has passed, due to the constant expansion of the universe, the light has been stretched to ever longer wavelengths – it has become redder. The first light waves that escaped after the Big Bang have now become microwaves, with wavelengths of several centimeters.

The weak background radiation

So the infrared light that Watts is interested in comes from events some time after The Big Bang. From the time the first stars were created, and the first galaxies took shape.

– Most research on early galaxies has looked at one galaxy at a time. But if you use only one telescope, such as the Hubble telescope, there are often so many galaxies in the field of view that they lie on top of each other. They cannot be separated from each other, says Watts.

The Watts research group with which he works at the University of Oslo has now received a total of 1.5 million euros, almost NOK 18 million, from the EU Research Council project for Origins, to separate the different galaxies from each other . And not least, distinguish radiation from space and radiation from dust in our own galaxy.

– The biggest problem with measuring cosmic background radiation is that the radiation is very weak, at the same time we live inside our own solar system, inside the The Milky Way, which is also full of cold, clear dust, explains Watts.

Following galaxies through cosmic time

So the best way to distinguish the Milky Way and the dust in our own solar system from the rest of the universe is to use many different data sets from different telescopes and add them to each other in a common model, Watts believes. It will therefore use historical data from, among others, JAXA’s AKARI satellite, NASA’s IRAS satellite and the upcoming SPHEREx, which will be operational from next year.

– These databases cover several decades of space observations, and so far they have only been analyzed in isolation. Now let’s put the data together in a general framework. It’s never been done before, says Watts.

If the researchers succeed, they will be able to display three-dimensional maps of space for different periods. In this way, one can study the development of the world over time.

– One of the most interesting things for me is being able to see how the brightness of the galaxies changes over time. Scientists have done this before, with very sensitive instruments, but only looked at very small areas at a time. What we are going to do is map almost the entire sky, and then divide it into different periods. This is how we should be able to follow galaxies that form through cosmic time, says Watts.