Can't wait for LISA to get going. 10 Years!
I too have been following this BH3 business:
My understanding is most Supernovae leave a Black Hole after exploding. And there must have been a lot of them down history. IDK whether they attract dark matter to complicate things. You would think they do.
I am currently experimenting with astrophotography, despite some murky skies lately and a cold NE wind at night. Hoping to see this Corona Borealis Nova. I bought a Nikon D60 DSLR with an 18-55mm f3.5-f5.6 lens.
Camera shake is proving problematic but I am picking up faint stars, but it is possible to use a 30 second manual timer delay mode, a shortened tripod and a piece of Black Card as a very manual and clever shutter control to avoid trails.
https://www.space.com/astrophotography-for-beginners-guide
These settings can be set in the menus, so I am optimistic.
I also want to get hold of my nephew's 35mm and 50mm f1.8 lenses which seem more suitable. F1.8 is four times the light of f3.5, which is a magnitude or more, magnitude being a x2.5 factor to be combined with longer shutter speed.
The Higgs Boson continues to baffle me, but am making some progress:
https://theconversation.com/peter-h...ut-the-building-blocks-of-the-universe-227638
The key seems to be that the Higgs field, which is scalar and uniquely spin-0, breaks the expected symmetry as a Mexican Hat or Wine Bottle potential. Symmetries conserve properties like energy and momentum, but the Higgs Field bypasses some of the problems in the Goldstone theories.
Uniquely, Peter Higgs predicted the Boson which bears his name. Around a massive 125 GeV along with the heavy W and Z bosons of the weak force and the Top Quark.
The 1964 Higgs paper was beyond me, though the equations in it are no worse than in General Relativity. and the 1966 one only available on subscription. Yukawa potentials and the Goldstone Theorem are of course, highly technical things.
Onwards and upwards!
I too have been following this BH3 business:
My understanding is most Supernovae leave a Black Hole after exploding. And there must have been a lot of them down history. IDK whether they attract dark matter to complicate things. You would think they do.
I am currently experimenting with astrophotography, despite some murky skies lately and a cold NE wind at night. Hoping to see this Corona Borealis Nova. I bought a Nikon D60 DSLR with an 18-55mm f3.5-f5.6 lens.
Camera shake is proving problematic but I am picking up faint stars, but it is possible to use a 30 second manual timer delay mode, a shortened tripod and a piece of Black Card as a very manual and clever shutter control to avoid trails.
https://www.space.com/astrophotography-for-beginners-guide
These settings can be set in the menus, so I am optimistic.
I also want to get hold of my nephew's 35mm and 50mm f1.8 lenses which seem more suitable. F1.8 is four times the light of f3.5, which is a magnitude or more, magnitude being a x2.5 factor to be combined with longer shutter speed.
The Higgs Boson continues to baffle me, but am making some progress:
https://theconversation.com/peter-h...ut-the-building-blocks-of-the-universe-227638
The key seems to be that the Higgs field, which is scalar and uniquely spin-0, breaks the expected symmetry as a Mexican Hat or Wine Bottle potential. Symmetries conserve properties like energy and momentum, but the Higgs Field bypasses some of the problems in the Goldstone theories.
Uniquely, Peter Higgs predicted the Boson which bears his name. Around a massive 125 GeV along with the heavy W and Z bosons of the weak force and the Top Quark.
The 1964 Higgs paper was beyond me, though the equations in it are no worse than in General Relativity. and the 1966 one only available on subscription. Yukawa potentials and the Goldstone Theorem are of course, highly technical things.
Onwards and upwards!
The following article from CERN makes a good stab at explaining spontaneous symmetry breaking in an understandable fashion:
https://home.cern/science/physics/higgs-boson/what
The attached gif shows a particle in the Mexican hat shape of the Higgs field (left) and a pencil standing on its tip (right) both show spontaneous symmetry breaking – symmetry is present, but only for a moment.
And now the hard bit:
Attachments
The information I have gleaned about the super-dense objects produced by supernovae is as follows:
- Stars smaller than eight Suns produce a white dwarf, the eventual predicted fate of our Sun.
- Stars about 8 and 30 times the mass of the Sun produce a neutron star up to around 2.3 solar masses.
- Stars over 30 solar masses become stellar-mass black holes.
Returning to the Gaia space telescope observations:
It should be stressed that Gaia has discovered a new class of black holes found in wide binary systems where the black hole and its companion star are far apart. These black holes emit no radiation and have been detected purely by their gravitational effects on their companion stars.
Previously, all the black holes astronomers knew of were discovered by emission of X-rays produced by material falling in. These emissions are from closer star-black hole pairs, called X-ray binaries.
The upshot is that we must adapt our theories about the evolution of binary star systems.
It should be stressed that Gaia has discovered a new class of black holes found in wide binary systems where the black hole and its companion star are far apart. These black holes emit no radiation and have been detected purely by their gravitational effects on their companion stars.
Previously, all the black holes astronomers knew of were discovered by emission of X-rays produced by material falling in. These emissions are from closer star-black hole pairs, called X-ray binaries.
The upshot is that we must adapt our theories about the evolution of binary star systems.
@Bonsai
Re post #3,945: "Stellar-mass black holes have masses ranging from about 3 times the mass of the Sun to about 50 times the mass of the Sun".
Yes, and this is completely in accord with the new Gaia discoveries.
However, I'm interested in how those with 3 times the mass of the Sun are formed in the first place.
Re post #3,945: "Stellar-mass black holes have masses ranging from about 3 times the mass of the Sun to about 50 times the mass of the Sun".
Yes, and this is completely in accord with the new Gaia discoveries.
However, I'm interested in how those with 3 times the mass of the Sun are formed in the first place.
In stars above 8 solar masses, as hydrogen in the core runs out helium fusion starts. Then as the helium runs out carbon fusion starts
This continues until the core is mainly iron when fusion reactions stop. The iron core will then collapse under gravity into a neutron star or a black hole.
So, I'm still interested in how black holes 3 times the mass of the Sun are formed in the first place.
If a star is less than about 8 solar masses carbon fusion will not be initiated and it ends up as a white dwarf.
In 2020, LIGO observed a 2.6 solar-mass black hole candidate. Where does it come from?
Solar-mass black holes are not expected from conventional stellar evolution astrophysics.
Could they originate from primordial black holes?
One theory is that if a neutron star captures a primordial black hole which devours it, a solar-mass black hole is left behind.
https://phys.org/news/2021-03-solar-mass-black-holes-dark.html
If a star is less than about 8 solar masses carbon fusion will not be initiated and it ends up as a white dwarf.
In 2020, LIGO observed a 2.6 solar-mass black hole candidate. Where does it come from?
Solar-mass black holes are not expected from conventional stellar evolution astrophysics.
Could they originate from primordial black holes?
One theory is that if a neutron star captures a primordial black hole which devours it, a solar-mass black hole is left behind.
https://phys.org/news/2021-03-solar-mass-black-holes-dark.html
Last edited:
Indeed!
Gaia's discoveries are making astrophysicists rethink the evolution of binary star systems, and we know little about primordial black holes.
Primordial black holes are thought to have formed when the density of the universe exceeded nuclear levels within the first microsecond of the big bang.
Chunks of early matter were crushed together so tightly that they condensed into singularities.
I think there is a lot of work to be done on the first 1^-6 seconds after the BB. The Higgs field AFAIK emerged at ~10^-12 seconds (so did gravity exist before that or was it of a different form?). But, given the inflationary expansion of the universe (from Guth et al), could primordial BH's even have had an opportunity to form? The general explanations as to why the universe did not simply collapse back in on itself in a massive BH catastrophe are (a) the BB was not taking place in an already established universe - it was the universe being actually created and (b) mass did not emerge early enough as a strong enough force to counteract Guth's inflation - in other words, the inflationary pressure was so great, it overcame any gravitational attraction. I can think of a 3rd one and that it the universe's density at that stage as still very uniform.
Last edited:
I do not understand why BH forming should involve any link to stellar nucleosynthesis conditions. Surely a BH forms only because the initial density is high enough? My understanding is there are stellar mass BH at the very low end of what's possible, and then once you get to higher Sun mass stars, the observed BH population ties up with the theory. The issue is there is a dip in observed BH populations in the 3-5 or 6 Sun mass stars that is not explainable.
Guth hypothesised that a rapid period of cosmic inflation occurred prior to the Big Bang and the creation of the Universe as we know it.
He postulates that an exponential expansion of the energy inherent in 'empty' space set up the conditions for the hot Big Bang.
Primordial black holes could not have formed during Guth's inflation when matter, antimatter, and radiation did not yet exist.
But yet it does! Stars of over 30 solar masses which go supernova become stellar-mass black holes.
NASA gives useful information on "The Life and Death of a Star" here: https://heasarc.gsfc.nasa.gov/docs/objects/snrs/snrstext.html
Surely, but how is that high enough density achieved other than in the gravitational collapse of the core of a massive star?
I'd be interested to know more about these observations of black hole populations. Do you have a link?
I found the chart below. Note that MASS GAP is accompanied by a question mark.
LIGO best detects the gravitational waves from massive black hole mergers.
The "EM Black Holes" are the ones detected by the emission of electromagnetic radiation, e.g., X-ray binaries.
The chart, from 2020, is explained here: https://skyandtelescope.org/astronomy-news/big-black-holes-dominate-new-gravitational-wave-catalog/
Quote from link:
Note that the recent Gaia observations are not included on the chart. Obviously we need to build up the data base to see the full picture.
Last edited:
Nice Galu. I had read about this a year or two back so could but recall where I'd seen it - I just realised, that is the graphic I saw. I think I picked it up in Flipboard.
re the collapse into a BH - AFAIK, stellar mass BH start at about 3x the Sun's mass and go up from there. So the question is, is that correct or not?
I picked this up from the web (see last paragraph):-
The discovery of TON 618 have created a new black hole species (already fingerprinted by M87 or even IC1101 cores): the ultramassive black holes with masses greater than 1010M⊙1010𝑀⊙. As said in the previous answer, in classical settings, there is no upper limit of the mass of black holes (I am not so sure if you get a theory beyond General Relativity even in classical settings).
Maybe, one day we will learn that quantum gravity says something about that. Interestingly, any supermassive, stellar, intermediate and ultramassive black hole has a mass much much greater than Planck mass, about a microgram. The issue is that we think quantum gravity applies only to VERY MASSIVE TINY (very dense) objects, not to very massive only. Indeed, any person has a mass much greater than Planck mass, but it is not "concentrated". When you have concentrated mass in very tiny regions, we have no idea of how to handle quantum fluctuations and amplitudes excepting with superstring theory. Another related question, is if you can have black holes of any DENSITY. Again, as said, you need to consider quantum processes like Hawking radiation, ... However, there is a subtle point, called the transplanckian problem. In principle, as the black holes evaporates it gets smaller and smaller, such as at certain size the wavelength would be lesser than the Planck length. We have to expect for a definitive theory of quantum gravity before to answer the ultimate fate of black holes and thus, the destiny of both: black holes and the whole universe (even the spacetime could be metastable and provisional/transitional state).
How large can a black hole formed from the collapse of a massive star grow in 1 Gyr? Suppose the black hole can grow as fast as it can. Suppose, by the moment, it satisfies the Eddington limit. Then, an exponential law follows up:
M˙=kM=M/τ𝑀˙=𝑘𝑀=𝑀/𝜏
where k=4⋅10−16s−1𝑘=4⋅10−16𝑠−1 for a ten solar masses inicial mass function accordingtly to the Eddington limit. Then, as
M=M0exp(kt)𝑀=𝑀0exp(𝑘𝑡)
Plugin into this formula M0=10M⊙𝑀0=10𝑀⊙ and the value of k, you get that the maximum mass it yields is in the range of ultramassive BH, i.e., Mf∼1010M⊙𝑀𝑓∼1010𝑀⊙ for a timescale about 1 Gyr (be aware, the numbers are tricky). Of course, transEddington limit is tricky, but there are some reasons to believe black holes bigger than 1010M⊙1010𝑀⊙ are unstable and eject material. Of course, in the absence of any other argument, the above argument does NOT provide an upper limit in principle. Only other considerations relativo to quasars and jets seem to apply. But the issue is a hot topic of debate in astrophysics. By the other hand, the minimal (or tiniest) black hole mass is also a mystery. In macroscale, we have NOT found black holes tinier than 3-5 solar masses (stellar black holes). However, primordial black holes or microblack holes could made some bits of the dark matter hidden in clusters and other parts of the galaxies. Again, the only hint are inflationary ideas, astronomical measures and experimental bounds (recently, it has been analyzed the probability of dark matter being totally black holes, but some evidence seems to say that that is not the case: black holes can not be all the dark matter).
re the collapse into a BH - AFAIK, stellar mass BH start at about 3x the Sun's mass and go up from there. So the question is, is that correct or not?
I picked this up from the web (see last paragraph):-
The discovery of TON 618 have created a new black hole species (already fingerprinted by M87 or even IC1101 cores): the ultramassive black holes with masses greater than 1010M⊙1010𝑀⊙. As said in the previous answer, in classical settings, there is no upper limit of the mass of black holes (I am not so sure if you get a theory beyond General Relativity even in classical settings).
Maybe, one day we will learn that quantum gravity says something about that. Interestingly, any supermassive, stellar, intermediate and ultramassive black hole has a mass much much greater than Planck mass, about a microgram. The issue is that we think quantum gravity applies only to VERY MASSIVE TINY (very dense) objects, not to very massive only. Indeed, any person has a mass much greater than Planck mass, but it is not "concentrated". When you have concentrated mass in very tiny regions, we have no idea of how to handle quantum fluctuations and amplitudes excepting with superstring theory. Another related question, is if you can have black holes of any DENSITY. Again, as said, you need to consider quantum processes like Hawking radiation, ... However, there is a subtle point, called the transplanckian problem. In principle, as the black holes evaporates it gets smaller and smaller, such as at certain size the wavelength would be lesser than the Planck length. We have to expect for a definitive theory of quantum gravity before to answer the ultimate fate of black holes and thus, the destiny of both: black holes and the whole universe (even the spacetime could be metastable and provisional/transitional state).
How large can a black hole formed from the collapse of a massive star grow in 1 Gyr? Suppose the black hole can grow as fast as it can. Suppose, by the moment, it satisfies the Eddington limit. Then, an exponential law follows up:
M˙=kM=M/τ𝑀˙=𝑘𝑀=𝑀/𝜏
where k=4⋅10−16s−1𝑘=4⋅10−16𝑠−1 for a ten solar masses inicial mass function accordingtly to the Eddington limit. Then, as
M=M0exp(kt)𝑀=𝑀0exp(𝑘𝑡)
Plugin into this formula M0=10M⊙𝑀0=10𝑀⊙ and the value of k, you get that the maximum mass it yields is in the range of ultramassive BH, i.e., Mf∼1010M⊙𝑀𝑓∼1010𝑀⊙ for a timescale about 1 Gyr (be aware, the numbers are tricky). Of course, transEddington limit is tricky, but there are some reasons to believe black holes bigger than 1010M⊙1010𝑀⊙ are unstable and eject material. Of course, in the absence of any other argument, the above argument does NOT provide an upper limit in principle. Only other considerations relativo to quasars and jets seem to apply. But the issue is a hot topic of debate in astrophysics. By the other hand, the minimal (or tiniest) black hole mass is also a mystery. In macroscale, we have NOT found black holes tinier than 3-5 solar masses (stellar black holes). However, primordial black holes or microblack holes could made some bits of the dark matter hidden in clusters and other parts of the galaxies. Again, the only hint are inflationary ideas, astronomical measures and experimental bounds (recently, it has been analyzed the probability of dark matter being totally black holes, but some evidence seems to say that that is not the case: black holes can not be all the dark matter).
Last edited:
Yes - so what is happening here is the core density goes up as stellar nucleosynthesis progresses through to the heavier elements, so I assume at 3x the Sun's mass, the density is enough to cause core collapse into a neutron star or BH. I cannot envisage a situation though where a star's elemental make-up is so different that it becomes a neutron star at the end of its life rather than a BH. So, the mass gap thing is indeed an interesting one.
On a separate note, I listened to a Brian Keating podcast a few days ago and the discussion was partly about time. The guest made an interesting point regarding gravitational waves. At the minute, LIGO measures 'strain' which is effective length change over ~4km distance using a laser source and some mirrors along with some stunning technology. The strain values are IIRC around 10^-22 so about 4 x 10^-17 metres. The guest on the podcast said there was another way to measure gravitational waves and that was with atomic clocks where the gravitational wave would change the rate at which time passed. So I suspect the idea is you put a number of clocks together, sync them up and then send them to their destinations a few million kms apart and then you monitor the time from each one. If a gravitational wave passes over the clocks, the times will change and you can post-process the data and capture the gravitational waves.