- Milky Way consists of very high amount of carbonaceous dust, and now similar type of cosmic dust has been observed in galaxies 11 billion light-years away from Earth.
- This comes from a recently detected ultraviolet carbonaceous dust in a gamma-ray burst, GRB180325A.
Galaxies are gravitationally bound systems comprised of numerous individual parts such as stars, stellar remnants, dark matter, interstellar gas, and dust. Even though cosmic dust grains are negligible in mass in the Universe, they play significant roles on a lot of astrophysical, astrochemical and astronomical aspects.
Cosmic dust grains are heat and coolant source in the interstellar and intergalactic medium, and an emission source in infrared wavelengths. They can both scatter and absorb light. Dust particles are also crucial for planetary science because they play a major role in planets’ formation. Therefore, more insights on cosmic dust could help us better understand our own existence on Earth.
Now, an international team of researchers has discovered the same type of cosmic dust that is known to exist in the Milky Way in a far distant galaxy that is nearly 11 billion light-years away from Earth. This type of event is rare, and the study provides more insight on what it takes for this specific type of cosmic dust to be formed.
How Did They Analyze Dust 11 Billion Years Away?
The size of most interstellar dust particles ranges between a few molecules to 0.1 micrometers. They are mostly small grains of carbon, aluminum, iron, silicon and other heavier elements.
Compared to other galaxies, the Milky Way consists of very high amount of carbonaceous dust. And, the main source of the stardust (matter left by stars) in our galaxy and the Magellanic Clouds is thought to be AGB (asymptotic giant branch) stars.
Similar type of cosmic dust has been observed in a few, far-away galaxies. Scientists have been able to analyze these galaxies using signals from gamma-ray bursts. These bursts are thought to be coming from supernova or hypernova rotating at extremely fast speed, massive star collapsing to form a neutron star, black hole, or quark star.
Gamma-ray bursts are the brightest electromagnetic events that last from 10 milliseconds to a few hours. A long-lasting ‘afterglow’ is emitted at higher wavelengths after a short flash of gamma rays.
By investigating these rays, scientists can learn what the galaxies are comprised of: they can measure the elemental materials and dust properties.
In this study, scientists have analyzed the recently detected ultraviolet carbonaceous dust in a gamma-ray burst, which has been assigned a name GRB180325A.
The Neil Gehrel’s Swift Observatory (a NASA space telescope) detected GRB180325A on 28th March 2018. When such an event is detected, astronomers try to observe it as rapidly as possible to capture the crucial data, which further enables them to investigate its source.
Researchers at the Niels Bohr Institute did the same. Their observations revealed an explosion of a star with a red shift of 2.25, meaning the signal has travelled nearly 11 billion light-years. The reading also confirmed the presence of carbonaceous dust in the source galaxy.
Then, they observed these bursts on the European Southern Observatory’s Very Large Telescope using X-shooter spectrograph, in Chile. Overall, 4 afterglow spectra were captured: all with an apparent detection of the carbonaceous dust.
This is not the first time astronomers have observed carbonaceous dust in gamma-ray bursts. These types of dust have previously been detected in 4 other gamma-ray bursts, the last of which was observed in 2007.
Similar observations in the future will enable us to learn more about far-away galaxies and perform a more systematic research on differences and similarities in dust composition throughout the ages of the Universe.