If you hadn’t read the headline, you would have mistaken this image as that of stars.
This is actually a detailed map of 25,000 black holes that are possibly eating planets and stars at this very moment.
“This is the result of many years of work on incredibly difficult data,” University of Hamburg astronomer, Francesco de Gasperin explained. “We had to invent new methods to convert the radio signals into images of the sky.”
How did astronomers create this map?
Using low radio frequencies and a Europe-sized radio telescope the Low Frequency Array (LOFAR) astronomers were able to map out these black holes.
The LOFAR is an interferometric network with 20,000 radio antennas across 52 areas in Europe.
Now, black holes are extremely hard to detect, especially when they don’t give off detectable radiation.
However, they’re identified when materials such as dust and gas are circling it. The intensity of the accreting process generates radiation that can be detected from Earth.
This map is now considered special by many astronomers and scientists because it showcases black holes that can be detected in ultra-low radio wavelengths.
The LOFAR.
IMAGE: LOFAR/LOL Survey.
To date, LOFAR is the only radio telescope that’s capable of detecting and taking high-resolution images of black holes that emit frequencies below 100 megahertz.
With four percent of the Northern sky covered, LOFAR intends to map out the entire area in ultra-low light frequencies through the LOFAR LBA Sky Survey (LoLSS).
However, it’s not going to be an easy task. Since the LOFAR is based on Earth and attempts to detect ultra-low frequency radio waves, the planet’s ionosphere poses a huge challenge.
Due to this, detecting black holes emitting frequencies below 5 megahertz is not a walk in the park.
Adding to the complexity of the challenge are the atmospheric conditions which can vary from time to time.
Algorithms.
Thankfully, astronomers have supercomputers which they use to run algorithms to correct ionospheric interference every four seconds.
“After many years of software development, it is so wonderful to see that this has now really worked out,” Leiden Observatory astronomer, Huub Röttgering reveals.
The process of correcting for the ionosphere has been extremely beneficial to scientists as well since they now not only are able to collect information about the black holes but use the LoLSS data generated to understand the ionosphere better.
Astronomers are hoping to discover objects below 50 megahertz through this process.
“The final release of the survey will facilitate advances across a range of astronomical research areas,” the astronomers wrote in their paper.
“(This) will allow for the study of more than 1 million low-frequency radio spectra, providing unique insights on physical models for galaxies, active nuclei, galaxy clusters, and other fields of research. This experiment represents a unique attempt to explore the ultra-low frequency sky at a high angular resolution and depth.”
Look out for the results of the study in Astronomy & Astrophysics when it’s published soon.
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Cover image sourced from LOFAR/LOL Survey.
It took scientists years to create this map.
