Book: ''' Stephen Hawking. A life in science ''
''Together with Brandon Carter and Jim Bardeen, Hawking wrote a paper,
published in Communications in Mathematical Physics , pointing out . . .
the team commented, '' In fact the effective temperature of a black hole
is absolute zero . . . . No radiation could be emitted from the hole.''
/ page 156./
But later (!) , . . using concepts of entropy and Heisenberg uncertainty
principle and quantum fluctuations (!) Hawking changed his mind
and wrote that black holes can radiate.
/ Book: ''' Stephen Hawking. A life in science '' by Michael White and John Gribbin/
# So, in the beginning ( according to calculations) the ''black hole''
had absolute zero temperature (like the Cosmic Vacuum: T=0K) . . .
but . . . thanks to entropy, Heisenberg uncertainty principle and
quantum fluctuations the absolute zero temperature was changed.
Conclusion:
Cosmic Vacuum and black holes are one and the same system.
Black holes are parts of the infinite Cosmic Vacuum.

Black holes aka Cosmic Vacuum.
At the core of the Milky Way galaxy, contains a supermassive black hole
of about 4.3 million solar masses.
Supermassive black holes with a mass between 0.1 million and 10 billion M☉.
Some astronomers have begun labeling black holes of at least
10 billion M☉ as ultramassive black holes.
Even larger ones have been dubbed stupendously large black holes
(SLABs) with masses greater than 100 billion M☉.
# A black hole with the same mass as the Sun would have a temperature
of about 0.06 millionth of a kelvin. Actual black holes are even larger
(at least about three times as massive as the Sun) so their temperature
is less than 0.02 millionth of a kelvin.
# 1- In classical theory black holes are objects with temperature T=0K.
Cosmic vacuum has the same temperature.
This means that black holes are part of the Cosmic Vacuum.
2- In quantum theory, due to entropy, quantum fluctuations of "virtual particles",
Heisenberg's Uncertainty Principle, the Cosmic Vacuum (so-called black holes)
will constantly vibrate.
3- A black holes will radiate at any temperature above absolute zero,
but at very cold temperatures it is very difficult to detect.
Conscusion:
Black holes are parts of the infinite/eternal Cosmic Vacuum.
The black holes are actually camouflaged the Cosmic Vacuum.
====