The cosmos is a mysterious place. They have discovered that black holes can bring dead stars back to life and create a “zombie” for a fleeting moment.
Close encounters with medium-sized black holes can reanimate dead stars, if only temporarily. This is suggested by a new study that has already been accepted for publication in The Astrophysical Journal.
A team of astronomers conducted computer simulations to determine what happens when a burned-out stellar corpse known as a white dwarf passes near an intermediate-mass black hole, which is home to between 1,000 and 10,000 times the mass of the Sun.
The researchers determined that the powerful gravity of the black hole can stretch and distort the previously inert entrails of the white dwarf so dramatically that nuclear fusion processes can be reactivated for seconds , converting helium, carbon and oxygen into heavier elements. like iron.
Such “tidal disruption events” can also generate gravitational waves, the waves in spacetime predicted by Albert Einstein a century ago and directly detected in 2015 by the Laser Interferometer Gravitational Wave Observatory (LIGO).
LIGO may not be able to capture these unique gravitational waves, the authors comment, but future instruments, such as the European Space Agency’s Laser Interferometry Space Antenna (LISA), which is scheduled for launch in 2034 , could.
And with huge amounts of extremely disturbed, that is, torn material, white dwarfs can be sucked into their ‘killer’ black holes, unleashing powerful bursts of radiation that current telescopes are capable of detecting.
Study black holes
The new results suggest a possible way to get better control of medium-sized black holes, which have proven surprisingly difficult to study. Astronomers have found many small (stellar-mass) black holes, and supermassive black holes containing millions or billions of solar masses are known to lurk at the heart of most, if not all, galaxies. But its middle cousins have remained elusive to date.
“ It is important to know how many intermediate black holes there are, as this will help answer the question where supermassive black holes come from, ” says Chris Fragile, co-author of the work. “Finding intermediate-mass black holes through tidal disruption events would be a tremendous advance.”
However, supermassive black holes are not great disruptors; monsters are likely to swallow a white dwarf before appreciably disturbing it, the researchers wrote.
No zombie stars have been observed , which is not surprising considering the extremely specific series of events required for it to happen, as well as the brief nature of the phenomenon.
The new study is not only of academic interest, as it describes a scenario in which our own Sun could end up enduring into the distant future. Every star that begins its life with approximately 8 solar masses or less will end up as a super dense white dwarf. That destiny is the one that awaits our Sun in 5,000 million years or so; After it depletes its hydrogen fuel reserve, it will swell into a red giant and then collapse into a white dwarf.
Reference: Relativistic Tidal Disruption and Nuclear Ignition of White Dwarf Stars by Intermediate Mass Black Holes. Peter Anninos, P. Chris Fragile, Samuel S. Olivier, Robert Hoffman, Bhupendra Mishra, Karen Camarda. Pre-print: arXiv: 1808.05664v1 [astro-ph.HE]
