
New type of black holes – Non interacting low-mass black hole - QueensGambit
https://science.sciencemag.org/content/366/6465/637
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hinkley
I still think one of the most terrifying tropes in sci fi is not alien
invasion but destruction by black hole. It's impersonal, and once it starts
it's inevitable, because of physics.

I really hope we never learn of the existence of black holes in the kiloton
range. If you think intelligences can annihilate themselves with nukes... how
about sucking your planet away from the inside out?

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ISL
The cross-section for capturing on the Sun is _much_ larger. The Sun is there,
and it is old. There are many Suns, and they are old. I'm unaware of the
observed sudden disappearance of a known star.

Ergo, the number of planet-destroying black holes running around is likely to
be small.

The much bigger risk is having Earth's orbit disrupted slightly by a passing
solar-mass scale black hole. We wouldn't get much warning that such a thing
was coming, but it could alter our orbit enough to get us into thermal
trouble.

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hinkley
So that'll depend on why the black holes arrive.

This article is about a binary system, which I would argue meets your
criteria.

If the black hole were manufactured, and/or being used as a weapon, there's no
reason it should hit the sun, and every reason it would hit a planet.

Now I think some of the other responses illustrated why this is not a problem
_if our current model of black holes is valid_. The "what if" in one of those
books I mentioned is "what if there was more exotic physics that allowed small
black holes to be stable?"

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QueensGambit
The low-mass black hole is thought to be 3.3 times the mass of our sun.
Previously, the smallest black hole discovered was 3.8 times the mass of our
sun. I guess this opens up a new breed of stars that are somewhere between
massive neutron star and low-mass black hole.

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keithwhor
A completely non-radiating mass — that’s smaller than any black hole we’ve
seen — in a binary orbit with a radiating star.

Doesn’t this fit the general criteria of a Dyson Sphere or Swarm?

Not to be all tin foil hat, just neat to think about.

~~~
pas
Dyson spheres/swarms do radiate heat (infrared).

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haolez
Why? Couldn’t it absorb almost all energy that “touches” it? Making it
impossible for us to detect the tiny amount of heat generated? Genuine
question.

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PeterisP
Energy can't disappear or be consumed - if energy doesn't get released out
then it gets absorbed i.e. accumulates; if it accumulates then the Dyson
sphere heats up a lot, if it heats up then it glows with blackbody radiation.

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haolez
Can we detect tiny amounts of blackbody radiation? Not that such a sphere
would release tiny amounts, but I'm curious about this as well.

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evanb
We can detect the CMB which, using the Stefan-Boltzmann law [s-b] and a CMB
temperature of 2.725 K, is about 3.12e-6 Watts/square meter. But, the CMB is
pervasive. The blackbody sphere you're asking about is very far away, and the
amount of power you'd receive scales like the inverse square of the distance
from the sphere to us here. So forget it, the CMB's blackbody energy flux
on/near Earth is ENORMOUS compared to the star's.

[s-b]
[https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law](https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law)

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NikolaeVarius
Reading the article, it seems that non-interacting is referring to the fact
that the black hole is hard to detect as there is no other star or gas source
to cause it to generate X-Rays as matter falls into it.

I find the name interesting since, mini black holes are one hypothesis
concerning Dark Matter, and also Weakly Interacting Massive Particles. Google
also doesn't seem like Non-interacting black holes are common nomenclature.
How do these names get created?

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pas
Someone writes a paper using the terminology, others refer to it, and it
sticks.

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willis936
Considering "weakly interacting" is already a very stuck name. By most
accounts these are typical black holes, which do not interact weakly, let
alone not at all. I don't think this name will stick.

~~~
greglindahl
"quiescent" is already in wide use referring to black holes, and "quiescent"
appears in the 2nd paragraph of this paper. Some stellar binary systems are
called "interacting".

~~~
fhars
And according to the full title of the paper, it is not the black hole that is
noninteracting, it is the binary system.

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sohkamyung
While the title of the paper says a low-mass black hole, the abstract does say
it could also be a high mass neutron star:

> Constraints on the giant’s mass and radius imply that the unseen companion
> is 3.3+2.8−0.7 solar masses, indicating that it is a noninteracting low-mass
> black hole or an unexpectedly massive neutron star.

Presumably, further observations will help determine what it is.

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noname6
This is happening in binary systems. The black hole is not emitting any
detectable X-rays from objects falling into it. There are none falling into it
then. It is non interacting.

But we know it is non interacting because it Doppler shifts a nearby object in
the binary systems these scientists are observing.

Being a binary system, unless the objects are at beyond perfect equilibrium
with respect to their accelerations, the objects will eventually collide (in a
true binary system). In other words, the Doppler shifting object must be
actually falling, however slowly, into the black hole.

My question is this: Can we assume that the object is heating up and emiting
additional x rays

