Black Hole or Neutron Star? Unknown 'Free-Floating' Compact Object in Milky Way Discovered Through Gravitational Microlensing

The University of California Berkeley carried out a study over a malicious cosmic object located lightyears away from our planet. Upon observations, the experts discovered that it was a 'free-floating' material that was first thought to be invisible.

The death of massive stellar bodies is theorized as the origin of the black holes. But despite being scattered across the Milky Way, only a few were identified due to some of them having invisible appearances.

Invisible, Dark Material in Milky Way

Black Hole or Neutron Star? Unknown ‘Free-Floating’ Compact Object in Milky Way Discovered Through Gravitational Microlensing
The first picture of a black hole was made using observations of the center of galaxy M87 taken by the Event Horizon Telescope. The image shows a bright ring formed as light bends in the intense gravity around a black hole 6.5 billion times the Sun’s mass. Event Horizon Telescope Collaboration / NASA

Today, scientists might have finally found a free-floating black hole or neutron star that was supposed to be invisible even for high-powered space telescopes. The material was charted with the help of light emissions from a distant star currently being distorted and consumed by the black hole's strong gravitational field.

Experts led the gravitational microlensing from UC Berkeley. According to their paper, the mass of the invisible object is approximately 1.6 to 4.4 times larger than our system's Sun. Previous studies have shown that a collapsing dead star should have at least 2.2 times the solar mass for a black hole to materialize. Because of this standard, the authors say that the material being a neutron star instead of a black hole is possible.

Scientists consider the mysterious object a stellar ghost, whether it is either a black hole or a neutron star. This is the first-ever observation of an actual dark stellar remnant discovered unpaired through gravitational microlensing.

According to the study's co-author Jessica Lu, Microlensing is an approach that could assist us in searching for lonely cosmic materials such as these compact objects and estimate their weight. The method allows us to see these dark objects that could not be perceived in another way, the expert continued.


Black Hole or Neutron Star?

Studies of compact objects hovering out on the galaxy are crucial to gaining more insights into the evolution of stars and the detailed phases of how they disappear. Determining these types of objects could also show us the features of unseen black holes, such as if they are primordial and scale to the ancients present during the Big Bang.

Lu and colleague Casey Lam, who also authored the study, carried out four other research on microlensing observations that involved neutron stars and white dwarfs. The series of studies conducted by the couple's team also revealed that at least 200 million black holes are dispersed throughout the Milky Way, further supporting previous estimates of the total population of black holes, Science Daily reports.

A separate team from the Space Telescope Science Institute (STScI) said that, according to their measurements, the compact object is near 7.1 solar masses. This suggests that the unseen matter, located at about 5,153 lightyears from us, might be a black hole all this time.

Further observations will be conducted in the future to present substantial information regarding this isolated mass gap. The studies will be published soon in The Astrophysical Journal Letters (1, 2).

Check out more news and information on Space in Science Times.

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