‘Those aren’t stars, they’re black holes’ -This map shows 25,000 supermassive black holes in the night sky

‘Those aren’t stars, they’re black holes’ -This map shows 25,000 supermassive black holes in the night sky
(Image credit: LOFAR/LOL Survey)

Key Takeaways:

  1. Astronomers have unveiled a groundbreaking map of the night sky, showcasing 25,000 supermassive black holes, marking a significant leap in cosmic cartography.
  2. Despite their invisibility, black holes are visualized through the effects of their gravitational pull on surrounding matter, offering insights into their presence and behavior.
  3. Relativistic jets, produced by black holes’ intense magnetic fields, emit detectable radio waves, aiding astronomers in their study and mapping endeavors.
  4. Years of meticulous work and innovative techniques were required to convert radio signals into celestial images, demonstrating the dedication of the astronomical community to unraveling cosmic mysteries.
  5. Advanced supercomputer algorithms play a pivotal role in correcting observational distortions caused by Earth’s ionosphere, showcasing the indispensable role of technology in modern astrophysics.

An extraordinary revelation has emerged from an international team of astronomers: a detailed chart of the night sky devoid of stars, instead showcasing 25,000 supermassive black holes.

You might be puzzled. How can we visualize something as elusive as black holes, which do not emit light? Contrary to popular belief, while black holes themselves remain invisible, their gravitational forces can tear apart nearby stars or celestial objects, forming a flattened disk known as an accretion disk.

The material within this disk whirls around the black hole’s event horizon at velocities approaching the speed of light. Occasionally, this material is expelled outward by the black hole’s intense magnetic field, generating particle jets at its magnetic poles.

These jets, termed relativistic jets, emit significant amounts of radio waves. Utilizing a network of 52 radio telescopes situated across Europe, known as the Low Frequency Array (LOFAR), astronomers have mapped these radio emissions in the northern skies.

Each white dot on the map is a supermassive black hole in a distant galaxy.  (Image credit: LOFAR/LOL Survey)

Lead researcher Francesco de Gasperin, previously affiliated with Leiden University and now at Universität Hamburg, Germany, remarked, “This achievement is the culmination of years of painstaking work with exceptionally challenging data. We had to devise novel techniques to translate the radio signals into celestial images.”

The remarkable map delineates low-frequency radio signals emanating from 25,000 supermassive black holes residing at the cores of distant galaxies. Remarkably, this mapping covers merely 4% of the northern hemisphere’s night sky. However, the researchers aspire to compile a comprehensive sky atlas featuring supermassive black holes observable from the northern hemisphere.

This map constitutes a segment of a forthcoming publication slated for Astronomy & Astrophysics.

Insight: Computational algorithms illuminate cosmic mysteries A significant challenge in observing radio waves emitted by supermassive black holes lies in their often low frequencies. Earth’s ionosphere poses a further obstacle, reflecting radio signals below 3MHz and distorting those up to 30MHz.

To overcome this hindrance, researchers devised a sophisticated supercomputer algorithm. This algorithm continuously corrected for ionospheric distortion at four-second intervals throughout 256 hours of observation.

Reflecting on this accomplishment, study co-author Huub Röttgering, Scientific Director of the Leiden Observatory, expressed, “After years of dedicated software development, witnessing the fruition of our efforts is immensely gratifying.”

This achievement follows in the footsteps of previous triumphs, notably in 2019 when Katie Bouman formulated an algorithm crucial to assembling data from the Event Horizon Telescope, yielding the groundbreaking image of a black hole’s event horizon.

Throughout the annals of astronomy, computational algorithms have played a pivotal role. As computing capabilities advance, so too does our capacity to unveil the mysteries of the universe.

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