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Sep 10 - The Theory of "MASS GAP" between NEUTRON STARS and BLACK HOLES just got rewritten


 
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 2 weeks ago '04        #1
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Exs  567 heat pts567
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Sep 10 - The Theory of "MASS GAP" between NEUTRON STARS and BLACK HOLES just got rewritten
 

 
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Whenever a star is born in the Universe, its eventual fate is almost completely determined from the moment nuclear fusion ignites in its core. Dependent only on a few factors — mass, the presence of elements heavier than helium, and whether it's part of a multi-star system — we can calculate with dramatic accuracy what the eventual fate of a star born with specific properties will be.

For most stars, including all the stars similar to our Sun, the eventual fate will be a white dwarf: an extremely dense collection of atoms more massive than dozens (or even hundreds) of Jupiters, but only the size of planet Earth. For more massive stars, though, a more catastrophic fate awaits: a supernova, which could either give rise to a neutron star or black hole remnant. There may or may not be a mass gap between the heaviest neutron stars and the lightest black holes formed by supernova, and humanity's never been in a better position to find out.

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The more massive a star is, the more material it has that's potentially usable as fuel for nuclear fusion. You might be inclined to think that with more fuel to burn, the more massive stars would live longer, but the exact opposite turns out to be true.

The way you form stars is via the collapse of a molecular cloud of gas. When you have more massive amounts of matter that go into forming your star, the collapse of that cloud traps greater amounts of heat inside, leading to greater core temperatures over a greater volume of space inside that star. Although achieving a temperature of 4,000,000 K (or so) inside a star's interior is enough to ignite nuclear fusion, greater temperatures lead to significantly faster rates of fusion, which equate to more luminous but shorter-lived stars.

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At the extreme high-mass end of the spectrum, stars can achieve temperatures of many tens or even hundreds of millions of Kelvin. When the abundance of hydrogen in the inner core drops below a critical threshold, the rate of fusion in the core begins to decrease, which means the outward pressure generated in the star's core also begins to drop. Since that was the primary force that counteracts all the gravitation working to collapse the star, running low on fuel implies that the star's core will begin to contract.

Whenever you have a large amount of matter that contracts rapidly (i.e., adiabatically), the temperature of that system will increase. For massive-enough stars, the contraction of the core will heat it sufficiently that it can start fusing additional elements. Beyond hydrogen fusion, helium can fuse into carbon. For stars more massive than about 8 times our Sun's mass, they'll go beyond that and fuse carbon, oxygen, neon, silicon, etc., until the inner core consists of elements like iron, nickel and cobalt: nuclei that can be fused no further.

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Starting in 2010, scientists who studied these binary systems that contained either neutron stars or black holes noticed something peculiar: while black holes as low as about 7 or 8 solar masses were observed, and neutron stars as massive as approximately 2 solar masses were seen, there was nothing discovered in between. In other words, between low-mass neutron stars and higher-mass black holes, there appeared to be a mass range, perhaps between 2-2.5 and 5-8 solar masses, where neither black holes nor neutron stars appeared to live.

Sure, there's always the possibility that we've made an incorrect a*sumption about the physics and astrophysics involved, but even those studies that consider it still cannot explain why there's such a steep drop-off in the number of sources seen below about 5 solar masses.

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it's possible that there's a good astrophysical reason for it. Not every star that's massive enough to go supernova will do so, as there are other possible fates awaiting such stars. They include:


gas-stripping from orbiting companions, leaving a degenerate core,

pair instability supernovae, where internal energies rise high enough that electron-positron pairs are spontaneously produced, resulting in the destruction of the entire massive star,

mergers with a companion, creating intermediate-mass objects that are relatively rare, or

direct collapse, as massive-enough stars could experience a cataclysm where the entire star collapses down to a black hole; such a phenomenon was observed for the first time directly just a few years ago.



It may be the case that supernova explosions that create neutron stars are fundamentally different from the ones that create black holes. If so, there may only be a small number of objects of greater mass than common neutron stars but of lower mass than common black holes. It's possible the only "mass gap" objects result entirely from the mergers of two neutron stars.

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So, is the mass gap real? Or are there plenty of neutron stars and/or black holes in this mass range that appears to be so sparsely populated today?

One possibility that would reveal the answer is to examine the presence of free-floating masses in the galaxy in a source-independent way. That can be accomplished by applying the science of gravitational microlensing: where a mass passes between our line-of-sight and a distant light source, causing a transient brightening-and-dimming of the background source in a fashion that's dependent only on the mass of the intervening mass.

The most recent microlensing studies take advantage of data from the ESA's Gaia mission, and find no evidence at all for this purported mass gap. Instead, they have uncovered a number of interesting microlensing candidates with exactly the masses you'd need to fill in this so-called gap.

Detecting massive objects like neutron stars and black holes with gravitational waves is a monumental accomplishment, but one that's limited by the sensitivity of your detector. When they exist in binary systems and spiral into one another, however, they emit gravitational radiation: a signal that a sensitive-enough detector can uncover. For a gravitational wave detector like LIGO, there are four things to consider:

The more massive your two inspiraling masses are, the greater the amplitude of your signal.
The closer in space the two masses are to one another, the greater the amplitude of the arriving signal.
The closer in space the merging masses are to you, the greater the amplitude of the arriving signal.
And the lower in mass these two masses are, the greater the amount of time they spend in the frequency range detectable by LIGO.
In other words, there's a trade off: more massive objects are detectable a greater distance away (over a larger spatial volume), but less massive objects spend more time in the frequency range LIGO is sensitive to.

On August 14, 2019, LIGO announced a candidate event that appeared to fall squarely within this "forbidden" mass range. While follow-up analysis likely indicates that this is a neutron star merging with a black hole rather than an object located in the "mass gap" regime, it's an enormous achievement to realize that LIGO, at long last, now possesses the capability of filling in the gap once and for all.

All in all, LIGO is on its way to picking up these lower-mass objects: the ones that fall in the "mass gap" range. We do not know where the most massive neutron star is, nor where the least massive black hole is. We do not know if merging binary neutron stars always produce black holes when they merge (something we think occurred for the one kilonova observed in 2017), and we do not know if such mergers are the only way that the Universe populates the mass gap region. But with more data from the current run of LIGO and Virgo — and future runs where the sensitivity is even further enhanced — astrophysicists might either confirm or destroy the notion of a mass gap entirely.

visit this link https://www.forbes.com/si .. /#3c020a07342a


Last edited by Exs; 09-10-2019 at 03:52 PM..
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 2 weeks ago '15        #2
PineappleOG  53 heat pts53
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Space isn’t real
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 2 weeks ago '04        #3
Exs  567 heat pts567 OP
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 PineappleOG said
Space isn’t real
willing to entertain the thought. Is space just a figment of the human imagination that has become a reality through millenia of wonder and detailed fruition of the imagination?
+2   

 2 weeks ago '18        #4
BXLeaks  5 heat pts5
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 PineappleOG said
Space isn’t real
Money aint real
Time aint real
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 2 weeks ago '18        #5
BIG FONT  22 heat pts22
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Yeah mane space aint real we live in a dome mane if you go too far you'll hit your head mane but thats ok cause when we die our spirit will float somewhere mane

 2 weeks ago '15        #6
PineappleOG  53 heat pts53
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 BXLeaks said
Money aint real
Time aint real
Nothing is real

 2 weeks ago '17        #7
Lazy  4 heat pts4
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BX sounding more and more like 8chan
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 2 weeks ago '18        #8
BXLeaks  5 heat pts5
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 PineappleOG said
Nothing is real
I'm real and more importantly.. I'm made up of a similar composite to what you say isn't real. In fact my chemical makeup and what I rely on for nutrition and strengths is on par with what's created when two planets collide.
+2   

 2 weeks ago '04        #9
Exs  567 heat pts567 OP
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 BXLeaks said
I'm real and more importantly.. I'm made up of a similar composite to what you say isn't real. In fact my chemical makeup and what I rely on for nutrition and strengths is on par with what's created when two planets collide.
That sir,

is the principle or law of Correspondence and there's a reason you feel that way.

because it's true

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 2 weeks ago '18        #10
BXLeaks  5 heat pts5
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 Exs said
That sir,

is the principle or law of Correspondence and there's a reason you feel that way.

because it's true




Movie gets sh*t on but I think it's underrated

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 2 weeks ago '18        #11
BIG FONT  22 heat pts22
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 BXLeaks said
I'm real and more importantly.. I'm made up of a similar composite to what you say isn't real. In fact my chemical makeup and what I rely on for nutrition and strengths is on par with what's created when two planets collide.
Take an helluva large fridge to hold 2 planets worth of food mane but if you had one you'd be straight for a long long time mane for real

 2 weeks ago '15        #12
PineappleOG  53 heat pts53
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 BXLeaks said
I'm real and more importantly.. I'm made up of a similar composite to what you say isn't real. In fact my chemical makeup and what I rely on for nutrition and strengths is on par with what's created when two planets collide.
You’re made up of space?

 2 weeks ago '18        #13
BXLeaks  5 heat pts5
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 PineappleOG said
You’re made up of space?
Earth

Which happens to be the planet we co-inhabit shared many similarities with our human form. It also happens to be part of space. A resident of space so to speak. Folks forget that

Our brains and bodies have very similar water-mass ratios for starters
but motr to the point of this particular thread... here's a direct neutron star/human similarity discovered a few years ago on a cellular level


 1 week ago '04        #14
Exs  567 heat pts567 OP
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 BXLeaks said
Earth

Which happens to be the planet we co-inhabit shared many similarities with our human form. It also happens to be part of space. A resident of space so to speak. Folks forget that

Our brains and bodies have very similar water-mass ratios for starters
but motr to the point of this particular thread... here's a direct neutron star/human similarity discovered a few years ago on a cellular level




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