Dark Matter Is Not Made Up Of Primordial Black Holes
We find that compact objects in the mass range from 1.8×10^−4M⊙ to 6.3M⊙ cannot compose more than 1% of dark matter, and compact objects in the mass range from 1.3×10^−5M⊙ to 860M⊙ cannot make up more than 10% of dark matter. This conclusively rules out primordial black hole mergers as a dominant source of gravitational waves.
From: https://arxiv.org/abs/2403.02386 Confirmed from the same data at https://arxiv.org/abs/2403.02398
arXiv:2403.03227 [pdf, other] On GR dragging and effective galactic dark matter Federico Re, Marco Galoppo Comments: 28 pages, 4 figures Subjects: General Relativity and Quantum Cosmology (gr-qc)
In recent years, there has been an increase in the number of papers regarding general-relativistic explanations for the dark matter phenomena in disc galaxies. The main focus of this scientific discussion is whether a previously unexamined relativistic dragging vortex could support flat rotation curves, with various research groups taking different stances on its feasibility. In this paper, we discuss the different points of view by placing the various arguments within a general theoretical context. We explicitly state the conceptual assumptions, and indicate what we believe to be the correct interpretation for the physical quantities of interest. We show how the dragging conjecture fails under certain hypotheses, and discuss the flaws of the most common dragging models: the linearised gravitomagnetic description and the one of Balasin&Grumiller. On the other hand, we illustrate how to avoid failure scenarios for the conjecture, emphasizing the features for a physically reasonable disc galaxy dragging model. In particular, we stress that the non-linearities of the Einstein Equations must play an essential role in generating what we define as ``pseudo-solitonic" solutions -- the only non-trivial physically viable solutions for the class of models considered. Furthermore, the dragging vortex is proven to show important contributions to the gravitational lensing in these models, thus providing an ulterior measure of its relevance. Moreover, by qualitatively exploring these pseudo-solitonic solutions, we find that a dragging speed of just a few kilometers per second would be enough to explain a non-negligible fraction of the galactic dark matter. Finally, we propose and analyse the feasibility of three independent measurements which could be carried out to detect the presence of dragging vortices in disc galaxies.
arXiv:2403.03839 (astro-ph) [Submitted on 6 Mar 2024] How open is the asteroid-mass primordial black hole window? Matthew Gorton, Anne M. Green
Primordial black holes (PBHs) can make up all of the dark matter (DM) if their mass, m, is in the so-called 'asteroid-mass window', 1017g≲m≲1022g. Observational constraints on the abundance of PBHs are usually calculated assuming they all have the same mass, however this is unlikely to be a good approximation. PBHs formed from the collapse of large density perturbations during radiation domination are expected to have an extended mass function (MF), due to the effects of critical collapse. The PBH MF is often assumed to be lognormal, however it has recently been shown that other functions are a better fit to numerically calculated MFs. We recalculate both current and potential future constraints for these improved fitting functions. We find that for current constraints the asteroid-mass window narrows, but remains open (i.e. all of the DM can be in the form of PBHs) unless the PBH MF is wider than expected. Future evaporation and microlensing constraints may together exclude all of the DM being in PBHs, depending on the width of the PBH MF and also the shape of its low and high mass tails.
Comments: 15 pages, 4 figures Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph) Cite as: arXiv:2403.03839 [astro-ph.CO]
arXiv:2402.17823 (astro-ph) [Submitted on 27 Feb 2024] Breakdown of Hawking Evaporation opens new Mass Window for Primordial Black Holes as Dark Matter Candidate Valentin Thoss, Andreas Burkert, Kazunori Kohri
The energy injection through Hawking evaporation has been used to put strong constraints on primordial black holes as a dark matter candidate at masses below 1017g. However, Hawking's semiclassical approximation breaks down at latest after half-decay. Beyond this point, the evaporation could be significantly suppressed as was shown in recent work. In this study, we review existing cosmological and astrophysical bounds on primordial black holes taking this effect into account. We show that the constraints disappear completely for a reasonable range of parameters, which opens a new window below 1010g for light primordial black holes as a dark matter candidate.
Comments: 8 pages, 5 figures, submitted to MNRAS Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th) Cite as: arXiv:2402.17823 [astro-ph.CO]
There is an independent constraint on PBHs and any other kind of heavy dark matter from the fact that it wouldn't be wave-like while the phenomena observed is wave-like.
Breakdown of Hawking Evaporation opens new Mass Window for Primordial Black Holes as Dark Matter Candidate Valentin Thoss, Andreas Burkert, Kazunori Kohri
and
arXiv:2403.03839 (astro-ph) [Submitted on 6 Mar 2024] How open is the asteroid-mass primordial black hole window? Matthew Gorton, Anne M. Green
you can evade those limits
also even Mcgaugh said MOND need dark matter for galaxies clusters
i didn't see Deur reference in arXiv:2403.03227
Conclusions The various criticisms raised in [49, 52, 53, 54, 50, 51] are valid for some dragging models in the literature, namely the gravitomagnetic case and BG. Nevertheless, a more refined model can avoid these flaws
btw you might like
arXiv:2402.19459 [pdf, other]Anomalous contribution to galactic rotation curves due to stochastic spacetimeJonathan Oppenheim, Andrea RussoSubjects
Hi Andrew, I need some help here. I'm reading Strassler's new book "Waves in an Impossible Sea". In chapter 6.4 he discusses the apparently well known fact that the total number of up and down quarks and anti quarks in a proton is not constant. Where as I was taught, back in the stone age, that a proton had two ups and a down. Which he lists as a constraint, that there are always three unpaired quarks (2u1d). Is this a rest energy thing where 2u1d is the lowest energy internal state, or are there always "many" quarks in the proton.
In addition what would a good place to start reading about this, or the correct search string to find papers?
The two ups and a down you heard about are called "valence quarks" and the others are called "sea quarks".
Strassler's web page discussion on the topic is actually very solid and understandable. See https://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-structure-of-matter/protons-and-neutrons/
The technical description of the sea quarks of a hadron like a proton or a neutron is called its "parton distribution function" (or PDF for short).https://en.wikipedia.org/wiki/Parton_(particle_physics) An 83 page scientific journal paper from the year 2000 is a good review article on the subject. https://www.osti.gov/servlets/purl/799541
In principle you can calculate a PDF from the equations and physical constants of the Standard Model of Particle Physics, but it is wickedly hard to do the calculations, so until maybe 4-5 years ago, these were compiled by just collecting data from gillions of collisions and fitting it to algebraic functions. See https://dispatchesfromturtleisland.blogspot.com/2020/05/progress-in-calculating-pdfs-from-first.html
Also, your statement that "the total number of up and down quarks and anti quarks in a proton is not constant" is true, but misleading, because it conceals one of the key relevant rules which is "conservation of baryon number", which holds that the total number of quarks minus the total number antiquarks in any system remains constant. https://en.wikipedia.org/wiki/Baryon_number
In all of history, there has never been an observed instance of conservation of baryon number being violated, although there is one process call the sphaleron interaction in the Standard Model of Particle Physics in which baryon number violation is theoretically possible at energies about 100 times as great as the Large Hadron Collider (the most powerful particle collider of all time). See generally, these posts at this blog: https://dispatchesfromturtleisland.blogspot.com/search?q=sphaleron
"Is this a rest energy thing where 2u1d is the lowest energy internal state, or are there always "many" quarks in the proton."
There are always many quarks in the proton, and the reason that they tell the "lies to children" version with 2u1d is that all of the observable properties of the proton can be derived from knowing there are the 2u and 1d valence quarks. All other quarks in the proton come in quark-antiquark pairs and wash out.
The best analogy to how we know about sea quarks that I've seen is the xkcd "fruit collider" comic that illustrates just how profoundly weird it is that there is so much more than the valence quarks in a proton or other hadron. See https://xkcd.com/1949/
A closely related concept is the Proton Spin Crisis. https://en.wikipedia.org/wiki/Proton_spin_crisis
The deal with this is that in every hadron, the total angular momentum (i.e. "spin") of the composite hadron as a whole is always a function of the sum of the spin of its valence quarks (which each can be plus or minus relative to each other). But, mysteriously, when you actually dig around inside a proton (or other hadron) looking for the sources of angular momentum in that composite particle that adds up to the sum of the spins of its valence quarks, this isn't where the angular momentum is actually located in the particles making up the proton. Some of its in the gluons, some of it is in the sea quarks, and far less than 100% of the total is in the valence quarks themselves. We really have no clue why this is so.
arXiv:2402.19459 [pdf, other]Anomalous contribution to galactic rotation curves due to stochastic spacetimeJonathan Oppenheim, Andrea RussoSubjects
Tuesday, March 12, 2024 Three Physics Mysteries Solved At Once: Postquantum Gravity For the first time in 4 decades, physicists have found a new approach to solving a problem which is almost a century old: How to combine quantum physics with gravity. I told you about this new approach, called “Postquantum Gravity” from Johnathan Oppenheim briefly before Christmas. He and his collaborators are now saying that their idea also explains dark matter and dark energy.
FYI, there haven't been many posts or long comments at this blog for a while because I was in Las Vegas for four days to support a team of six runners in their half marathon and then got COVID on the way home and was very sick for about a week and a half (and I am still not 100%).
Dark Matter Is Not Made Up Of Primordial Black Holes
any comment on
arXiv:2403.03839 (astro-ph) [Submitted on 6 Mar 2024] How open is the asteroid-mass primordial black hole window? Matthew Gorton, Anne M. Green
Primordial black holes (PBHs) can make up all of the dark matter (DM) if their mass, m, is in the so-called 'asteroid-mass window', 1017g≲m≲1022g.
arXiv:2402.17823 (astro-ph) [Submitted on 27 Feb 2024] Breakdown of Hawking Evaporation opens new Mass Window for Primordial Black Holes as Dark Matter Candidate Valentin Thoss, Andreas Burkert, Kazunori Kohri
The energy injection through Hawking evaporation has been used to put strong constraints on primordial black holes as a dark matter candidate at masses below 1017g. However, Hawking's semiclassical approximation breaks down at latest after half-decay. Beyond this point, the evaporation could be significantly suppressed as was shown in recent work. In this study, we review existing cosmological and astrophysical bounds on primordial black holes taking this effect into account. We show that the constraints disappear completely for a reasonable range of parameters, which opens a new window below 1010g for light primordial black holes as a dark matter candidate.
Best wishes Andrew, hope you recover quickly. I was hit by two months of lethargy after my own covisd illness about a year ago. Take it easy for a while.
"Primordial black holes (PBHs) can make up all of the dark matter (DM) if their mass, m, is in the so-called 'asteroid-mass window', 1017g≲m≲1022g."
Solar system orbits of various kinds of planets and asteroids rule out the asteroid window.
"The energy injection through Hawking evaporation has been used to put strong constraints on primordial black holes as a dark matter candidate at masses below 1017g. However, Hawking's semiclassical approximation breaks down at latest after half-decay. Beyond this point, the evaporation could be significantly suppressed as was shown in recent work. In this study, we review existing cosmological and astrophysical bounds on primordial black holes taking this effect into account. We show that the constraints disappear completely for a reasonable range of parameters, which opens a new window below 1010g for light primordial black holes as a dark matter candidate."
Hawking radiation is a quick and easy way to eliminate light PBH matter as a DM candidate. So, there hasn't been a lot written on other constraints on it. But, for example, any DM candidate really needs to be 10 keV or less so that its behavior can be "wave-like" as observations require.
"Hawking radiation is a quick and easy way to eliminate light PBH matter as a DM candidate. So, there hasn't been a lot written on other constraints on it.
the paper is written on other constraints on it
from the abstract
arXiv:2402.17823 (astro-ph) [Submitted on 27 Feb 2024] Breakdown of Hawking Evaporation opens new Mass Window for Primordial Black Holes as Dark Matter Candidate Valentin Thoss, Andreas Burkert, Kazunori Kohri "However, Hawking's semiclassical approximation breaks down at latest after half-decay. Beyond this point, the evaporation could be significantly suppressed as was shown in recent work. "
"But, for example, any DM candidate really needs to be 10 keV or less so that its behavior can be "wave-like" as observations require."
Hum... That Hawking Evaporation paper (and the papers they reference) are based on the assumption that information can not be destroyed. If you assume that information can be permanently lost in a BH then that constraint goes away. Obviously that would blow a lot of modern physics out of the ballpark, but as has been observed by many theorists, nature is not constrained to be simple and to match our simple theories.
Conservation of information is one way to get there, but Hawking radiation is a concept that doesn't inherently rely on conservation of information. The basic concept behind Hawking radiation is that the pair production and destruction associated with sea quarks in hadrons happens on either side of an event horizon of a black hole with a predictable and calculable frequency, with half of the produced pair within it and half of the produced pair escaping the black hole. This can be derived from conservation of mass-energy and CPT and lepton number and baryon number which are very well demonstrated in other contexts, without an information conservation condition that is more speculative.
arXiv:2403.03227 [pdf, other]
ReplyDeleteOn GR dragging and effective galactic dark matter
Federico Re, Marco Galoppo
Comments: 28 pages, 4 figures
Subjects: General Relativity and Quantum Cosmology (gr-qc)
In recent years, there has been an increase in the number of papers regarding general-relativistic explanations for the dark matter phenomena in disc galaxies. The main focus of this scientific discussion is whether a previously unexamined relativistic dragging vortex could support flat rotation curves, with various research groups taking different stances on its feasibility. In this paper, we discuss the different points of view by placing the various arguments within a general theoretical context. We explicitly state the conceptual assumptions, and indicate what we believe to be the correct interpretation for the physical quantities of interest. We show how the dragging conjecture fails under certain hypotheses, and discuss the flaws of the most common dragging models: the linearised gravitomagnetic description and the one of Balasin&Grumiller. On the other hand, we illustrate how to avoid failure scenarios for the conjecture, emphasizing the features for a physically reasonable disc galaxy dragging model. In particular, we stress that the non-linearities of the Einstein Equations must play an essential role in generating what we define as ``pseudo-solitonic" solutions -- the only non-trivial physically viable solutions for the class of models considered. Furthermore, the dragging vortex is proven to show important contributions to the gravitational lensing in these models, thus providing an ulterior measure of its relevance. Moreover, by qualitatively exploring these pseudo-solitonic solutions, we find that a dragging speed of just a few kilometers per second would be enough to explain a non-negligible fraction of the galactic dark matter. Finally, we propose and analyse the feasibility of three independent measurements which could be carried out to detect the presence of dragging vortices in disc galaxies.
@neo
ReplyDeleteNice paper. Doesn't consider non-perturbative effects however.
arXiv:2403.03839 (astro-ph)
ReplyDelete[Submitted on 6 Mar 2024]
How open is the asteroid-mass primordial black hole window?
Matthew Gorton, Anne M. Green
Primordial black holes (PBHs) can make up all of the dark matter (DM) if their mass, m, is in the so-called 'asteroid-mass window', 1017g≲m≲1022g. Observational constraints on the abundance of PBHs are usually calculated assuming they all have the same mass, however this is unlikely to be a good approximation. PBHs formed from the collapse of large density perturbations during radiation domination are expected to have an extended mass function (MF), due to the effects of critical collapse. The PBH MF is often assumed to be lognormal, however it has recently been shown that other functions are a better fit to numerically calculated MFs. We recalculate both current and potential future constraints for these improved fitting functions. We find that for current constraints the asteroid-mass window narrows, but remains open (i.e. all of the DM can be in the form of PBHs) unless the PBH MF is wider than expected. Future evaporation and microlensing constraints may together exclude all of the DM being in PBHs, depending on the width of the PBH MF and also the shape of its low and high mass tails.
Comments: 15 pages, 4 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
Cite as: arXiv:2403.03839 [astro-ph.CO]
arXiv:2402.17823 (astro-ph)
ReplyDelete[Submitted on 27 Feb 2024]
Breakdown of Hawking Evaporation opens new Mass Window for Primordial Black Holes as Dark Matter Candidate
Valentin Thoss, Andreas Burkert, Kazunori Kohri
The energy injection through Hawking evaporation has been used to put strong constraints on primordial black holes as a dark matter candidate at masses below 1017g. However, Hawking's semiclassical approximation breaks down at latest after half-decay. Beyond this point, the evaporation could be significantly suppressed as was shown in recent work. In this study, we review existing cosmological and astrophysical bounds on primordial black holes taking this effect into account. We show that the constraints disappear completely for a reasonable range of parameters, which opens a new window below 1010g for light primordial black holes as a dark matter candidate.
Comments: 8 pages, 5 figures, submitted to MNRAS
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
Cite as: arXiv:2402.17823 [astro-ph.CO]
There are solar system constrains on asteroid sized PBHs.
ReplyDeleteThere is an independent constraint on PBHs and any other kind of heavy dark matter from the fact that it wouldn't be wave-like while the phenomena observed is wave-like.
ReplyDeleteif you combine
ReplyDeleteBreakdown of Hawking Evaporation opens new Mass Window for Primordial Black Holes as Dark Matter Candidate
Valentin Thoss, Andreas Burkert, Kazunori Kohri
and
arXiv:2403.03839 (astro-ph)
[Submitted on 6 Mar 2024]
How open is the asteroid-mass primordial black hole window?
Matthew Gorton, Anne M. Green
you can evade those limits
also even Mcgaugh said MOND need dark matter for galaxies clusters
i didn't see Deur reference in arXiv:2403.03227
Conclusions
The various criticisms raised in [49, 52, 53, 54, 50, 51] are valid for some dragging models in the literature,
namely the gravitomagnetic case and BG. Nevertheless, a more refined model can avoid these flaws
btw you might like
arXiv:2402.19459 [pdf, other]Anomalous contribution to galactic rotation curves due to stochastic spacetimeJonathan Oppenheim, Andrea RussoSubjects
Hi Andrew,
ReplyDeleteI need some help here. I'm reading Strassler's new book "Waves in an Impossible Sea". In chapter 6.4 he discusses the apparently well known fact that the total number of up and down quarks and anti quarks in a proton is not constant. Where as I was taught, back in the stone age, that a proton had two ups and a down. Which he lists as a constraint, that there are always three unpaired quarks (2u1d). Is this a rest energy thing where 2u1d is the lowest energy internal state, or are there always "many" quarks in the proton.
In addition what would a good place to start reading about this, or the correct search string to find papers?
Cheers,
Guy
The two ups and a down you heard about are called "valence quarks" and the others are called "sea quarks".
ReplyDeleteStrassler's web page discussion on the topic is actually very solid and understandable. See https://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-structure-of-matter/protons-and-neutrons/
The technical description of the sea quarks of a hadron like a proton or a neutron is called its "parton distribution function" (or PDF for short).https://en.wikipedia.org/wiki/Parton_(particle_physics) An 83 page scientific journal paper from the year 2000 is a good review article on the subject. https://www.osti.gov/servlets/purl/799541
In principle you can calculate a PDF from the equations and physical constants of the Standard Model of Particle Physics, but it is wickedly hard to do the calculations, so until maybe 4-5 years ago, these were compiled by just collecting data from gillions of collisions and fitting it to algebraic functions. See https://dispatchesfromturtleisland.blogspot.com/2020/05/progress-in-calculating-pdfs-from-first.html
Also, your statement that "the total number of up and down quarks and anti quarks in a proton is not constant" is true, but misleading, because it conceals one of the key relevant rules which is "conservation of baryon number", which holds that the total number of quarks minus the total number antiquarks in any system remains constant. https://en.wikipedia.org/wiki/Baryon_number
In all of history, there has never been an observed instance of conservation of baryon number being violated, although there is one process call the sphaleron interaction in the Standard Model of Particle Physics in which baryon number violation is theoretically possible at energies about 100 times as great as the Large Hadron Collider (the most powerful particle collider of all time). See generally, these posts at this blog: https://dispatchesfromturtleisland.blogspot.com/search?q=sphaleron
"Is this a rest energy thing where 2u1d is the lowest energy internal state, or are there always "many" quarks in the proton."
ReplyDeleteThere are always many quarks in the proton, and the reason that they tell the "lies to children" version with 2u1d is that all of the observable properties of the proton can be derived from knowing there are the 2u and 1d valence quarks. All other quarks in the proton come in quark-antiquark pairs and wash out.
The best analogy to how we know about sea quarks that I've seen is the xkcd "fruit collider" comic that illustrates just how profoundly weird it is that there is so much more than the valence quarks in a proton or other hadron. See https://xkcd.com/1949/
A closely related concept is the Proton Spin Crisis. https://en.wikipedia.org/wiki/Proton_spin_crisis
The deal with this is that in every hadron, the total angular momentum (i.e. "spin") of the composite hadron as a whole is always a function of the sum of the spin of its valence quarks (which each can be plus or minus relative to each other). But, mysteriously, when you actually dig around inside a proton (or other hadron) looking for the sources of angular momentum in that composite particle that adds up to the sum of the spins of its valence quarks, this isn't where the angular momentum is actually located in the particles making up the proton. Some of its in the gluons, some of it is in the sea quarks, and far less than 100% of the total is in the valence quarks themselves. We really have no clue why this is so.
ReplyDeletesabine
http://backreaction.blogspot.com/
reviews
arXiv:2402.19459 [pdf, other]Anomalous contribution to galactic rotation curves due to stochastic spacetimeJonathan Oppenheim, Andrea RussoSubjects
Tuesday, March 12, 2024
Three Physics Mysteries Solved At Once: Postquantum Gravity
For the first time in 4 decades, physicists have found a new approach to solving a problem which is almost a century old: How to combine quantum physics with gravity. I told you about this new approach, called “Postquantum Gravity” from Johnathan Oppenheim briefly before Christmas. He and his collaborators are now saying that their idea also explains dark matter and dark energy.
another GR MOND besides Deur
@neo
ReplyDeleteThanks for the heads up.
@all
FYI, there haven't been many posts or long comments at this blog for a while because I was in Las Vegas for four days to support a team of six runners in their half marathon and then got COVID on the way home and was very sick for about a week and a half (and I am still not 100%).
Hi Andrew, Thanx for information and all the references!
ReplyDeleteDark Matter Is Not Made Up Of Primordial Black Holes
ReplyDeleteany comment on
arXiv:2403.03839 (astro-ph)
[Submitted on 6 Mar 2024]
How open is the asteroid-mass primordial black hole window?
Matthew Gorton, Anne M. Green
Primordial black holes (PBHs) can make up all of the dark matter (DM) if their mass, m, is in the so-called 'asteroid-mass window', 1017g≲m≲1022g.
arXiv:2402.17823 (astro-ph)
[Submitted on 27 Feb 2024]
Breakdown of Hawking Evaporation opens new Mass Window for Primordial Black Holes as Dark Matter Candidate
Valentin Thoss, Andreas Burkert, Kazunori Kohri
The energy injection through Hawking evaporation has been used to put strong constraints on primordial black holes as a dark matter candidate at masses below 1017g. However, Hawking's semiclassical approximation breaks down at latest after half-decay. Beyond this point, the evaporation could be significantly suppressed as was shown in recent work. In this study, we review existing cosmological and astrophysical bounds on primordial black holes taking this effect into account. We show that the constraints disappear completely for a reasonable range of parameters, which opens a new window below 1010g for light primordial black holes as a dark matter candidate.
Best wishes Andrew, hope you recover quickly. I was hit by two months of lethargy after my own covisd illness about a year ago. Take it easy for a while.
ReplyDelete@neo
ReplyDelete"Primordial black holes (PBHs) can make up all of the dark matter (DM) if their mass, m, is in the so-called 'asteroid-mass window', 1017g≲m≲1022g."
Solar system orbits of various kinds of planets and asteroids rule out the asteroid window.
"The energy injection through Hawking evaporation has been used to put strong constraints on primordial black holes as a dark matter candidate at masses below 1017g. However, Hawking's semiclassical approximation breaks down at latest after half-decay. Beyond this point, the evaporation could be significantly suppressed as was shown in recent work. In this study, we review existing cosmological and astrophysical bounds on primordial black holes taking this effect into account. We show that the constraints disappear completely for a reasonable range of parameters, which opens a new window below 1010g for light primordial black holes as a dark matter candidate."
Hawking radiation is a quick and easy way to eliminate light PBH matter as a DM candidate. So, there hasn't been a lot written on other constraints on it. But, for example, any DM candidate really needs to be 10 keV or less so that its behavior can be "wave-like" as observations require.
ReplyDelete@ andrew
"Hawking radiation is a quick and easy way to eliminate light PBH matter as a DM candidate. So, there hasn't been a lot written on other constraints on it.
the paper is written on other constraints on it
from the abstract
arXiv:2402.17823 (astro-ph)
[Submitted on 27 Feb 2024]
Breakdown of Hawking Evaporation opens new Mass Window for Primordial Black Holes as Dark Matter Candidate
Valentin Thoss, Andreas Burkert, Kazunori Kohri
"However, Hawking's semiclassical approximation breaks down at latest after half-decay. Beyond this point, the evaporation could be significantly suppressed as was shown in recent work. "
"But, for example, any DM candidate really needs to be 10 keV or less so that its behavior can be "wave-like" as observations require."
that papers assume Newtonian gravity
Hum... That Hawking Evaporation paper (and the papers they reference) are based on the assumption that information can not be destroyed. If you assume that information can be permanently lost in a BH then that constraint goes away. Obviously that would blow a lot of modern physics out of the ballpark, but as has been observed by many theorists, nature is not constrained to be simple and to match our simple theories.
ReplyDelete@Guy
ReplyDeleteConservation of information is one way to get there, but Hawking radiation is a concept that doesn't inherently rely on conservation of information. The basic concept behind Hawking radiation is that the pair production and destruction associated with sea quarks in hadrons happens on either side of an event horizon of a black hole with a predictable and calculable frequency, with half of the produced pair within it and half of the produced pair escaping the black hole. This can be derived from conservation of mass-energy and CPT and lepton number and baryon number which are very well demonstrated in other contexts, without an information conservation condition that is more speculative.