The team now wants to perform an optical spectroscopy to better understand the seven candidates.
There is always a question about life forms other than humans out there in the Universe. Recently, an international team of researchers, based in Sweden, India, the US and the UK, devised a way to search for unimaginably complex extraterrestrial megastructures, known as Dyson spheres, according to a report by Science Alert.
A Dyson sphere is a hypothetical engineering project that only highly advanced civilisations can build. These Dyson spheres would allow a civilisation to harness all of a star's energy. To find Dyson spheres, or rather their technosignatures, the ''Project Hephaistos'' was created. The team of scientists published their results in the Monthly Notices of the Royal Academy of Sciences.
The team believes that they've identified seven such spheres lurking in the cosmos after filtering through millions of potential space objects. Scientists believe that only civilisations capable of such a project are those who measure Level II on the Kardashev scale. However, these candidates need further analysis to determine their nature.
The prospect of such a construction was first proposed by physicist and astronomer Freeman J. Dyson back in 1960. He envisioned them as a solar-system-sized shell consisting of a ''swarm of objects'' that could travel on independent orbits around a star, such as our sun.
As per Indy.com, the idea behind this is that the aliens commandeering this multi-faceted sphere would use it to harness the energy of the star to fulfil the energy needs of its technologically sophisticated people.
How did scientists find the seven potential Dyson spheres?
The team first analysed data gathered by the European Space Agency's Gaia map of stars, as well as the 2MASS infrared astronomical survey and NASA's WISE infrared astronomy space telescope.
"This structure would emit waste heat in the form of mid-infrared radiation that, in addition to the level of completion of the structure, would depend on its effective temperature. A specialized pipeline has been developed to identify potential Dyson sphere candidates focusing on detecting sources that display anomalous infrared excesses that cannot be attributed to any known natural source of such radiation," Matias Suazo, of Sweden's Uppsala University explained.
However, the issue here is that plenty of other natural objects emit excess infrared radiation, including nebulae and background galaxies, as per Universe Today. So, scientists developed a special pipeline to detect anomalies that display anomalous infrared excesses.
''[This] pipeline has been developed to identify potential Dyson sphere candidates focusing on detecting sources that display anomalous infrared excesses that cannot be attributed to any known natural source of such radiation," the researchers said.
They narrowed it down to 368 sources. 328 were rejected as blends. Of these, 29 were rejected as irregulars, and four were rejected as nebulars. Only seven potential candidates were left out of about 5 million initial objects.
"All sources are clear mid-infrared emitters with no clear contaminators or signatures that indicate an obvious mid-infrared origin," they added.
The team now wants to perform an optical spectroscopy to better understand the seven candidates.