The first post on this blog was made on May 22, 2011. In the first 14 years of this blog, which ended on May 21, 2025, I made 2805 posts, which is just slightly more than 200 posts per year.
Unlike its sister blog, Wash Park Prophet, the number of posts per year has been fairly consistent for this entire time period.
I have made minor updates to my two conjectures pages to reflect new developments and correct errors of spelling, grammar, and style, and to enhance clarity.
Editor’s summaryFrom our origins in Africa, humans have migrated and settled across the world. Perhaps none of these migrations has been the subject of as much debate as the expansion into and throughout the Americas. Gusareva et al. used 1537 whole-genome sequenced samples from 139 populations in South America and Northeast Eurasia to shed light on the population history of Native Americans. Collected as a part of the GenomeAsia 100K consortium, analysis of these data showed that there are four main ancestral lineages that contributed to modern South Americans. These lineages diverged from each other between 10,000 and 14,000 years ago, and this analysis reveals more details of the population history dynamics in these groups. —Corinne SimontiAbstractGenome sequencing of 1537 individuals from 139 ethnic groups reveals the genetic characteristics of understudied populations in North Asia and South America. Our analysis demonstrates that West Siberian ancestry, represented by the Kets and Nenets, contributed to the genetic ancestry of most Siberian populations. West Beringians, including the Koryaks, Inuit, and Luoravetlans, exhibit genetic adaptation to Arctic climate, including medically relevant variants.
In South America, early migrants split into four groups—Amazonians, Andeans, Chaco Amerindians, and Patagonians—~13,900 years ago. Their longest migration led to population decline, whereas settlement in South America’s diverse environments caused instant spatial isolation, reducing genetic and immunogenic diversity. These findings highlight how population history and environmental pressures shaped the genetic architecture of human populations across North Asia and South America.AbstractINTRODUCTIONDuring the late Pleistocene, humans expanded across Eurasia and eventually migrated to the Americas. Those who reached Patagonia, at the southern tip of South America, completed the longest migration out of Africa.RATIONALEThe extent of basal divergences, admixture, and degrees of isolation among Indigenous North Eurasian and Native South American populations remain debated, with most insights derived from genome-wide genotyping data. This study aims to deepen our understanding of the ancient dynamics that shaped contemporary populations in North Eurasia and the Americas. By using large-scale whole-genome sequencing of 1537 individuals from 139 ethnic groups in these regions, we examined population structures, elucidated prehistoric migrations, and explored the influence of past environmental factors on the diversification of human populations.RESULTSAdvances in large-scale genomic sequencing have considerably enhanced our understanding of the genetic ancestry of human populations across North Eurasia and South America. Our analysis reveals that all contemporary Siberians, as well as some Northeast Europeans and Central Asians, share ancestry with the West Siberian groups, represented by the Kets and Nenets. Their ancestors were widespread across Siberia 10,000 years ago (ya), but now these groups face population decline by 73.6% and are becoming a minority.The populations of west Beringia, including the Koryaks, Inuit, and Luoravetlans, are the most genetically distinct from other Siberians. These groups have adapted to Arctic conditions with genetic variations related to lipid metabolism, thermogenesis, sensory perception, and the regulation of reproductive and immune functions.
We were not able to identify a specific Siberian group as the direct ancestors of Native Americans owing to deep divergence and limited genetic continuity. However, west Beringian populations remain closely related to Native Americans. Koryaks and Inuit show 5 and 28% Native American ancestry, respectively, owing to gene flow between 700 and 5100 ya.We estimated the split time of Native South Americas into Amazonians, Andeans, Chaco Amerindians, and Patagonians to have occurred 13,900 to 10,000 ya. Migration and settlement across the continent led to population isolations due to geographic boundaries and a reduction in their genetic diversity, particularly affecting immune genes, such as the human leukocyte antigen (HLA) genes. Over the past 10,000 years, all four Native South American lineages have experienced population declines ranging from 38 to 80%. This dramatic decline, combined with the loss of traditional lifestyles, cultural practices, and languages, has pushed some Indigenous communities, such as the Kawésqar, to the brink of extinction.CONCLUSION
The migration to an uninhabited continent of South America through the narrow Isthmus of Panama resulted in a founder effect among Native South Americans, leading to reduced genetic diversity compared with that of Indigenous populations of North Eurasia. Over 13,900 years, geographic barriers within the continent further isolated Indigenous groups, subsequently reducing genetic diversity. These groups faced a profound challenge with the arrival of European colonists in the 1600s, who introduced new adversities that threatened their long-standing endurance.
Genetic ancestry and nucleotide diversity.
Colors represent genetic ancestries estimated by whole-genome sequencing data of contemporary human populations. Countries having no data remained empty. Circle size indicates the average nucleotide diversity of each population.
The late Pleistocene saw the expansion of humans into the frigid lands of Eurasia. The earliest known presence of modern humans in northern Eurasia at latitudes greater than 50°N was around 45,000 years ago (ya) in West Siberia, and by 31,600 ya, humans had migrated far east toward Beringia, north of the Arctic Circle at 71° N. The earliest human remains identified in this region are two Yana Rhinoceros Horn Site individuals that, despite their extreme Northeast Siberian geographical location, show substantial genetic relatedness to early West Eurasian hunter-gatherers.
The Upper Palaeolithic people who initially populated Northeast Siberia were then replaced by arrivals from East Asia. The Kolyma1 remains, excavated near the Chukotka region and dated as being from 9800 ya, demonstrate greater affinity to East Asians and present-day west Beringian populations, such as Koryaks and Luoravetlans (also known as Chukchi), as well as to Native Americans. The linguistic and cultural diversity of present-day Indigenous Siberian populations is mirrored by the complex patterns of admixture, as shown by genome-wide genotype data analysis. This genetic structure in Siberians, comprising several ancestral components, is estimated to have emerged within the past 10,000 to ~3400 years. The Western Eurasian ancestry component presented in a majority of Indigenous Siberian populations is not the result of postcolonial Russian admixture but one of the ancient components dating back to 12,500 to 25,000 ya in different Siberian populations. Among the present-day populations of Northeast Eurasia, the Koryaks from the Kamchatka Peninsula and the Inuit from Chukotka show the closest genetic relatedness to Native North Americans.
The migration of humans to the Americas occurred when the Bering Land Bridge was still open, with the earliest human remains in North America found in the Clovis burial site in western Montana dating back to around 12,700 ya. However, recent evidence suggests human presence in North America from at least 23,000 ya. By the time the Ice-Free Corridor opened up and became suitable for travel around 13,300 ya, humans were already widely dispersed in North America, likely owing to Pacific coastal migration routes. The divergence between northern and southern Native American populations is estimated to have occurred between 17,500 and 14,600 ya south of the North American ice sheets, according to modern and ancient genomic analyses. The rapid dispersal of humans in South America is suggested by archaeological records, which date the earliest human presence in North Patagonia, the southernmost tip of the Americas, to 14,500 ya. However, the number of basal divergences, founding populations, admixture, and the degrees of isolation among Native South American populations remain a subject of debate, with most of the current understanding coming from analyses of genome-wide genotyping or ancient DNA data. Additionally, fine-scale population genetic studies based on high-coverage whole-genome sequencing datasets for contemporary populations of North Eurasia and South America have not been performed to date.
The population split time estimates also suggest that the divergence of the four Native South American lineages occurred over a short period, from 13,900 to 10,000 ya. All four lineages show a continuous population decline. However, the Andean highlanders managed to maintain their population size during the rise of maize horticulture around 5200 to 3700 ya. It has declined by 45.1% since then (Ne from 1771 to 972), whereas Chaco Amerindians have declined by 46.89% (Ne from 1448 to 769) since 10,000 ya. Amazonians and especially Patagonians have seen a dramatic decrease in population size over the past 10,000 years, with declines of 66.59% (Ne from 1368 to 457) and 79.68% (Ne from 1171 to 238), respectively.
To assess the impact of population decline on genetic diversity, we estimated genome-wide runs of homozygosity (ROHs) segments. In Native South Americans, the average number and length of ROHs segments estimated across all populations were 10.5 and 1.3 times higher than those in Africans (Yoruba) and 3.75 and 1.2 times higher than those in Northeast Europeans, respectively. The highest abundance of extended ROHs was observed in Amazonians, Patagonian Kawésqar, and Chaco Amerindians and was similar to that seen in isolated island populations, such as the Andamanese and Baining. This high homozygosity is likely the result of the founder effect due to long-distance migration and/or population isolation. The strong correlation between the average total number of ROHs and the average nucleotide diversity (Pearson correlation coefficient r = –0.78) supports the idea that the extended homozygosity is a result of population history.
The body text of the discussion section notes that:
Our analysis of whole-genome datasets also allowed us to infer the split time between North Eurasians and Native Americans, which occurred between 26,800 and 19,300 ya. This finding is consistent with estimates based on the recently published paleontological discovery of human footprints in North America (south-central New Mexico) dating back to 23,000 and 21,000 ya, as well as with other genetic studies, despite differences in the cohorts that were investigated.
A previous study of ancient genomes suggests limited genetic continuity in Beringia, as the most recent Arctic colonization occurred 6000 ya. Therefore, it is likely that the first ancestors of the Native Americans in this region were replaced by the most recent wave of migration. We could not identify a specific Siberian group as direct Native American ancestors among the contemporary Indigenous populations in our dataset. However, we show that west Beringian populations, such as Inuit, Luoravetlans, and Koryaks, are genetically the closest to Native Americans. Moreover, we revealed the gene flow from Native Americans back to Inuit and Koryaks in Chukotka and the Kamchatka Peninsula between 700 to 5100 ya. Our analyses also demonstrated the shared ancestry between the west Beringian populations and contemporary Native North Americans, particularly the Chipewyan from Canada. This genetic relatedness is consistent with the PCA results. These findings are in line with previous reports that describe multiple waves of Northeast Asian gene flow into North Americans, including Neo-Inuit lineages.
By using our genome sequencing data from diverse Native South Americans, we have discovered that the simultaneous split of the four Native South American ancestral lineages occurred between 13,900 and 10,000 ya from a common ancestral population in Mesoamerica. This rapid radial dispersal and the establishment of sedentary settlements across South America are supported by previous genetic studies and the archaeological findings of early technologies (such as stone tools) that indicate regional cultural diversification in South America from at least 13,000 ya. This divergence occurred shortly after the split of the ancestral Native American lineages into northern and southern branches, which happened between 17,500 and 14,600 ya south of the North American ice sheets. By the time the Ice-Free Corridor was fully opened 14,300 to 13,300 ya during the abrupt warming, humans were already widely dispersed in North America.
Our study shows that the human migration across South America resulted in population splits with a loss of genetic diversity due to founder effects. Geographical and environmental boundaries caused population isolation and further enhanced the genetic homogenization, similar to islander populations. The demographic history has greatly influenced the Patagonian Kawésqar, whose ancestors migrated the farthest distance out of Africa. They have the smallest effective population size and one of the smallest genetic distances between community members. It has been reported that contemporary Native Patagonians (including the Kawésqar) show the highest genetic affinity to ancient Patagonian maritime individuals that lived 1000 ya, indicating genetic continuity in the region. Our study cannot provide evidence for the reported back migration from the Southern Cone along South America's Atlantic coast owing to a lack of data on east coastal Native South American populations.
Our study also suggests that close genetic relatedness in Indigenous populations, along with reduced heterozygosity in HLA genes, may impact antigen recognition ability to new unexposed pathogens. In combination with socioeconomic factors and limited access to medical care, this could pose a potential health risk. High–pathogen load regions, such as Southeast Asia, tend to have a higher diversity of promiscuous HLA-DRB1 alleles, which allows them to respond to a wider range of extracellular pathogens. However, emerging evidence that divergent allele advantage (a mechanism where the HLA genotypes present a broader set of epitopes) and increase in HLA alleles promiscuity level may counterplay the effect of loss of heterozygosity in HLA genes. Our work highlights a noteworthy implication for future research in population-based disease cohorts: Epitope-binding repertoire studies are essential for identifying the dynamic effects of limited HLA diversity on disease susceptibility.
Access to the vastness of the South American continent was constrained by the relatively small landmass of the Isthmus of Panama. Consequently, migrating groups could only inhabit the continent from a singular direction, limiting the genetic diversity of human individuals. This ultimately led to the emergence of the four ancestries described in our analysis. Although Indigenous groups managed to maintain their populations for over 13 millennia with minimal interaction with other groups, their endurance faced a critical challenge with the arrival of the initial colonists in the 1600s.
Modified Newtonian Dynamics (MOND) is an alternative to the dark matter hypothesis that attempts to explain the "missing gravity" problem in astrophysics and cosmology through a modification to objects' dynamics. Since its conception in 1983, MOND has had a chequered history. Some phenomena difficult to understand in standard cosmology MOND explains remarkably well, most notably galaxies' radial dynamics encapsulated in the Radial Acceleration Relation. But for others it falls flat -- mass discrepancies in clusters are not fully accounted for, the Solar System imposes a constraint on the shape of the MOND modification seemingly incompatible with that from galaxies, and non-radial motions are poorly predicted. An experiment that promised to be decisive -- the wide binary test -- has produced mainly confusion. This article summarises the good, the bad and the ugly of MOND's observational existence. I argue that despite its imperfections it does possess ongoing relevance: there may yet be crucial insight to be gleaned from it.
It has been claimed in a number of publications that neutrinos can exhibit chirality oscillations. In this note we discuss the notion of chirality and show that chiral neutrino oscillations in vacuum do not occur. We argue that the incorrect claims to the contrary resulted from a failure to clearly discriminate between quantum fields, states and wave functions. We also emphasize the role played in the erroneous claims on the possibility of chirality oscillations by the widely spread misconceptions about negative energies.
We present the current Standard Model (SM) prediction for the muon anomalous magnetic moment, aμ, updating the first White Paper (WP20) [1].
The pure QED and electroweak contributions have been further consolidated, while hadronic contributions continue to be responsible for the bulk of the uncertainty of the SM prediction. Significant progress has been achieved in the hadronic light-by-light scattering contribution using both the data-driven dispersive approach as well as lattice-QCD calculations, leading to a reduction of the uncertainty by almost a factor of two.
The most important development since WP20 is the change in the estimate of the leading-order hadronic-vacuum-polarization (LO HVP) contribution. A new measurement of the e+e−→π+π− cross section by CMD-3 has increased the tensions among data-driven dispersive evaluations of the LO HVP contribution to a level that makes it impossible to combine the results in a meaningful way. At the same time, the attainable precision of lattice-QCD calculations has increased substantially and allows for a consolidated lattice-QCD average of the LO HVP contribution with a precision of about 0.9%.
Adopting the latter in this update has resulted in a major upward shift of the total SM prediction, which now reads a(SM)(μ) = 116592033(62) × 10^−11 (530 ppb). When compared against the current experimental average based on the E821 experiment and runs 1-3 of E989 at Fermilab, one finds a(exp)(μ)−a(SM)(μ) = 26(66) × 10^−11, which implies that there is no tension between the SM and experiment at the current level of precision. The final precision of E989 is expected to be around 140 ppb, which is the target of future efforts by the Theory Initiative. The resolution of the tensions among data-driven dispersive evaluations of the LO HVP contribution will be a key element in this endeavor.
By comparing the uncertainties of Eq. (9.5) and Eq. (9.4) it is apparent that the precision of the SM prediction must be improved by at least a factor of two to match the precision of the current experimental average, which will soon be augmented by the imminent release of the result based on the final statistics of the E989 experiment at Fermilab. We expect progress on both data-driven and lattice methods applied to the hadronic contributions in the next few years. Resolving the tensions in the data-driven estimations of the HVP contribution is particularly important, and additional experimental results combined with further scrutiny of theory input such as from event generators should provide a path towards this goal. Further progress in the calculation of isospin-breaking corrections, from both data-driven and lattice-QCD methods, should enable a robust SM prediction from τ data as well. For lattice-QCD calculations of HVP continuing efforts by the world-wide lattice community are expected to yield further significant improvements in precision and, hopefully, even better consolidation thanks to a diversity of methods. The future focus will be, in particular, on more precise evaluations of isospin-breaking effects and the noisy contributions at long distances.
The role of aµ as a sensitive probe of the SM continues to evolve. We stress that, even though a consistent picture has emerged regarding lattice calculations of HVP, the case for a continued assessment of the situation remains very strong in view of the observed tensions among data-driven evaluations. New and existing data on e+e− hadronic cross sections from the main collaborations in the field, as well as new measurements of hadronic τ decays that will be performed at Belle II, will be crucial not only for resolving the situation but also for pushing the precision of the SM prediction for aµ to that of the direct measurement. This must be complemented by new experimental efforts with completely different systematics, such as the MUonE experiment, aimed at measuring the LO HVP contribution, as well as an independent direct measurement of aµ, which is the goal of the E34 experiment at J-PARC. The interplay of all these approaches, various experimental techniques and theoretical methods, may yield profound insights in the future, both regarding improved precision in the SM prediction and the potential role of physics beyond the SM. Finally, the subtleties in the evaluation of the SM prediction for aµ will also become relevant for the anomalous magnetic moment of the electron, once the experimental tensions in the determination of the fine-structure constant are resolved.
Basically, the conclusion calls for scientists to get to the bottom of why the experiments that were used as a basis for the first White Paper prediction were wrong, and hopes against all reasonable expectations that the process of doing that will reveal new physics.
The paper's claim that the uncertainty in the Standard Model prediction can be cut dramatically "in the next few years" is pretty much wishful thinking.
This paper doesn't address in detail how completely this result ruled out new physics, but further papers by unaffiliated scientists will no doubt do just that not long after the new experimental results are released next week.
Asymptotically Weyl-invariant gravity (AWIG) is further developed within the Palatini formalism as a power-counting renormalizable alternative to general relativity (GR). An expression for the dimensionless exponent n(R) is derived based on dynamical dimensional reduction. We show that this version of AWIG naturally resolves several theoretical issues normally associated with the Palatini formalism.
A falsifiable prediction regarding the frequency of gravitational waves from binary black hole mergers is made. A preliminary analysis of gravitational wave GW150914 yields a maximum tension of 0.9 sigma with GR and marginally favours AWIG. A similar analysis of gravitational wave GW151226 yields a maximum tension of 2.7 sigma with GR and favours AWIG more significantly.
The first dedicated Z-boson mass measurement at the LHC with Z→μ+μ− decays is reported. The dataset uses proton-proton collisions at a centre-of-mass energy of 13 TeV, recorded in 2016 by the LHCb experiment, and corresponds to an integrated luminosity of 1.7 fb−1. A template fit to the μ+μ− mass distribution yields the following result for the Z-boson mass, m(Z) = 91184.2 ± 8.5 ± 3.8 MeV, where the first uncertainty is statistical and the second systematic. This result is consistent with previous measurements and predictions from global electroweak fits.
Stacy McGaugh's latest post at his Triton Station blog explains why Big Bang Nucleosynthesis (BBN) poses a challenge to the LambdaCDM Standard Model of Cosmology.
Basically, BBN favors a lower primordial baryon density as of the time of nucleosynthesis, while the cosmic microwave background (CMB) astronomy data when interpreted in light of the LambdaCDM model in a model-dependent way, favors a primordial baryon density as of the time of nucleosynthesis that is two times higher.
But, there are lots of technical issues that make the 4-5 sigma discrepancy less obviously an irreconcilable conflict than it might otherwise seem to be.
I'm skeptical of all of the theories described in the abstract below, but I lack the expertise to say with confidence that none of them are correct.
I am skeptical because, in short, I think that a more accurate description of gravity which gives rise to apparent dark matter and dark energy phenomena, and a mirror universe model in which an anti-matter universe very similar to our own flows backwards in time from the Big Bang, is likely to explain the observations that inflationary cosmology seeks to explain without requiring an exceedingly brief moment of cosmological inflation very shortly after the Big Bang.
There are peer reviewed published articles that make claims along these lines, but I haven't devoted the time necessary to gain a firm grasp of this literature.
We give a brief review of the basic principles of inflationary theory and discuss the present status of the simplest inflationary models that can describe Planck/BICEP/Keck observational data by choice of a single model parameter. In particular, we discuss the Starobinsky model, Higgs inflation, and α-attractors, including the recently developed α-attractor models with SL(2,ℤ) invariant potentials. We also describe inflationary models providing a good fit to the recent ACT data, as well as the polynomial chaotic inflation models with three parameters, which can account for any values of the three main CMB-related inflationary parameters A(s), n(s) and r.
We introduce Scale Factorized-Quantum Field Theory (SF-QFT), a framework that performs path-integral factorization of ultraviolet (UV) and infrared (IR) momentum modes at a physical scale Q∗ before perturbative expansion.
This approach yields a UV-finite effective action whose Wilson coefficients Ci(Q) and coupling aeff(Q) are fixed by matching to experiment. Because the two-loop β-function is universal in massless QCD, aeff(Q) evolves with a scheme-independent equation, with higher-order β-coefficients absorbed into the Ci.
Applying SF-QFT to the inclusive ratio Re+e− gives RSF−QFT(31.6GeV) = 1.04911 ± 0.00084, in excellent agreement with experiment (Rexp(31.6GeV) = 1.0527 ± 0.005) while requiring orders of magnitude fewer calculations than a conventional four-loop MS-bar approach.
We find universal algebraic recursion relations that generate all higher-order contributions without additional Feynman diagrams, yielding scheme-invariant predictions with remarkable convergence. SF-QFT provides a rigorous proof for the existence of a positive mass gap in Yang-Mills theory, resolving one of the Millennium Prize Problems by demonstrating how non-perturbative effects emerge naturally from the path-integral factorization.
For QED, the same formalism integrates out high-energy modes above Q∗, producing scheme-independent predictions for the electron anomalous magnetic moment with unprecedented precision (a(theory)(e) = 0.001 159 652 183 56(76)).
SF-QFT heralds a paradigm shift in quantum field theory, replacing the pursuit of ever-higher loop orders with a unified framework that handles both perturbative and non-perturbative physics while maintaining manifest gauge invariance and eliminating renormalization ambiguities.
As of 2016, the coefficients of the QED formula for the anomalous magnetic moment of the electron are known analytically up to and have been calculated up to order :The QED prediction agrees with the experimentally measured value to more than 10 significant figures, making the magnetic moment of the electron one of the most accurately verified predictions in the history of physics. (See Precision tests of QED for details.)
The current experimental value and uncertainty is:
My previous post was number 2800 at this blog, which is one week short of 14 years old today, so I'm averaging just slightly over 200 posts a year, which is not quite 4 posts a week.
The question, which I'm musing over and want to post now so I don't let it slip my mind, because it's interesting (even though I'm not yet ready to answer it) is:
What would be the most shocking and revolutionary scientific discovery you can think of that is possible, but currently seems unlikely to you?
To be clear, I mean scientific discoveries and not technological break throughs with existing scientific knowledge or highly foreseeable and expected new scientific discoveries. So, for example, vast improvements in quantum computing, or discovering a cure for some major kind of cancer, don't count.
Also, the answer to this question has a subjective element.
For example, the majority view among astrophysicists is that some form of dark matter particle which is beyond the Standard Model exists, so discovering one wouldn't be all that surprising to them. But this would be much more surprising to me, as I believe that dark matter phenomena are much more likely to have a cause rooted in some sort of gravitational effect.
Perhaps the most shocking discovery, to me, in the last few years, has been the discovery of human footprints in New Mexico dated to 22,000 years ago (well inland, close in time to but prior to the Last Glacial Maximum that was a barrier to settlement further south, and 8,000 years earlier that the southern migration of the primary human population of the Americas). These Progenitors, however, failed to thrive and left very few definitive traces of their presence.
Feel free to add you own answers to this question in the comments.
Overview: An Improvement But Worse Than MOND
Another day, another dark matter particle model.
This time, a spin-0 massive scalar boson and a spin-1 massive vector boson. Unsurprisingly with the additional degree of freedom that two bosonic dark matter particles can provide relative to single dark matter particle models, it can fit the data a little better than most one parameter dark matter particle models.
The authors "fix the vector boson mass µV = 9 × 10^−26 eV across all galaxies[.]" They allow "the scalar boson mass to vary in the range µS ∈ [10^−10, 10^−16] eV." [Ed. I have converted the MeV units used in the paper for the scalar boson mass to eV units for ease of comparison.]
The vector boson mass is (as is typical of ultralight bosonic dark matter models) of the same order of magnitude as the mass-energy of a typical graviton (for which there is also an obvious theoretical basis for gravitons to vary in mass-energy), suggesting a convergence towards the predictions of a gravitationally based explanation for dark matter phenomena with properties similar to a massless tensor (spin-2) graviton.
The second scalar bosonic dark matter particle found in dark matter sub-halos, however, has less of a clear analog for that mass scale, although the behavior of a scalar boson and a tensor boson have a lot of similarities. The authors of the paper note that:"The origin of this second DM source is unknown, which somehow points to a limitation of the model."
The model doesn't explain why the mass of the scalar bosonic dark matter candidate varies in average mass by a factor of a million from one galaxy to another, despite the fact that all of the bosonic dark matter of both types is assumed to be in its ground state in every galaxy, which is necessary for it to produce the assumed halos shapes.
To be charitable, however, the number of sub-halos times the mass of each sub-halo could be addressed by varying the number of sub-halos rather than the mass of the dark matter particles in each sub-halo.
But this would create a different problem. The size of each dark matter sub-halo in the model is basically a function of the mass of the scalar bosonic dark matter candidate (related to its reduced Compton wave length), but not all dark matter sub-halos that are inferred from rotation dynamics and gravitational lensing are the same size.
With three parameters: a fixed vector dark matter particle mass, a scalar dark matter particle mass which can be fit to the data on a galaxy by galaxy basis, and a factor to scale the total amount of dark matter to the total galaxy mass on a case by case basis, with a basically fixed and well-motivated formula for the halo and sub-halo shapes, this model it does almost as well at fitting a galactic rotation curve as a much simpler single fixed parameter MOND model with no parameters that vary from galaxy to galaxy, as shown in the figures below from the paper, although eyeballing it (I've seen the MOND fits to the rotation curves of many similar galaxies many times), it doesn't look like quite as tight a fit.
This model can't predict the total mass of the galaxy from the luminous matter distribution in the way that MOND does, without also resorting to the Tully-Fischer relationship to which MOND is equivalent. And, this model doesn't provide any theoretical explanation for the systemic variation in the mass-luminosity ratio from one galaxy to the next that MOND does.
Given the additional two degrees of freedom in this two type bosonic dark matter model, it's Chi-square fit should have a Chi-square fit two better than a MOND fit, which would be very tight indeed, instead of being sightly worse.
This model also, at least point, has been tested in a much narrower domain of applicability than MOND. It has basically only been tested in selected spiral galaxies in the SPARC sample, while MOND has been fit to essentially all galaxies of all shapes from smallest to largest. MOND doesn't work quite right in galaxy clusters, but this model hasn't been tested in galaxy clusters, so it provides nothing to compare to there. And, while simple extensions of MOND have been fit neatly to the cosmic microwave radiation background (CMB), and there are single particle type dark matter models that have been fit to the CMB, I have not yet seen a two particle type dark matter fit to the CMB and I'm not even really sure who that would work when one of the dark matter particle types has a mass that varies by a factor of a million from one galaxy to the next.
This is an improvement over models that took fifteen or so free parameters to fit galactic rotation curves as well as MOND, that I blogged about quite a few years ago, which still wasn't really any more predictive than this model. But, it is also definitely a work in progress that has multiple problems to solve before it is an attractive dark matter particle model that fits all of the data well.
Observations of galaxy and galaxy cluster rotation curves reveal a striking deviation from classical expectations. Instead of exhibiting a Keplerian decline, the measured velocities remain unexpectedly flat, extending far beyond the visible boundaries of galaxies. This persistent flatness, commonly known as the Rotation Curves (RC) problem, constitutes a critical argument in favor of non-baryonic dark matter (DM). Various theories have been proposed to explain these anomalies. Some authors have suggested modifications to Newtonian gravity, while others advocate for the existence of invisible, non-interacting DM. The early observations of the Coma cluster together with more precise measurements of galaxy RC during the 1970s reinforced the DM hypothesis. Freeman’s model of spherical halos introduced the concept of a linearly increasing mass function, and subsequent studies have mapped DM halos exceeding quantitatively the observable galactic regions.The possibility that galactic halos could be composed of bosonic DM has also been investigated in several works. In particular, models incorporating an ultralight axion-like particle have attracted much attention, as they naturally give rise to DM halos modeled as Newtonian Bose-Einstein Condensates. The Scalar Field Dark Matter model, which is consistent with the ΛCDM paradigm, predicts large-scale phenomena that align with linear-order perturbations. By employing ground state solutions of the Schrödinger-Poisson (SP) system—the only stable configuration where all bosonic particles reside in the lowest energy state—these models successfully reproduce the observed RC. Stability analyses further confirm that while the ground state is robust against gravitational perturbations, excited state configurations remain inherently unstable.Models in which a bosonic field minimally coupled to gravity acts as a source of DM are directly linked with bosonic stars. These can be primarily classified into scalar boson stars (BS) and Proca stars (PS), which are localized, regular, horizonless solutions modeled by massive, free or self-interacting, complex scalar and vector fields bound by gravity, respectively. Recent advances have expanded this framework to include ProcaHiggs stars (PHS), where complex vectors interact with real scalars to yield richer dynamics. Moreover, investigations into multi-field configurations have led to the development of multi-state boson stars and ℓ-bosonic stars, thereby broadening the spectrum of viable models.
Ed. Proca theories were initially devised as massive photon theories. They don't actually describe the behavior of photons well, but does provide the propagators for massive spin-1 bosons, which include the W and Z bosons of the Standard Model.
The vector boson dark matter candidate is essentially a sterile Z boson (i.e. one that unlike the Z boson doesn't interact via the weak force) that is 35 orders of magnitude less massive than a Z boson. The scalar bosonic dark matter candidate is a massive spin-0 boson, much like a sterile Higgs boson (i.e. one that doesn't interact via any non-gravitational force), but 21 to 27 orders of magnitude less massive than the Standard Model Higgs boson. The vector dark matter candidate is about 9 to 15 orders of magnitude less massive than the scalar dark matter candidate.
The primary dark matter halo component has to be less massive than the subhalo dark matter component, because the size of the Bose-Einstein condensate boson star distribution of a less massive bosonic dark matter candidate is large enough to extend across the entire galaxy, while the size of the Bose-Einstein condensate boson start distribution of a more massive bosonic dark matter candidate is only large enough to extend across a dark matter subhalo which is much smaller than a galaxy.
The theoretical feasibility of bosonic stars has been extensively examined, particularly regarding their formation mechanisms, stability conditions, and dynamical behavior. While initially conceptually conceived as static and spherically symmetric objects, modern studies now routinely explore rotating configurations that manifest as axisymmetric, spinning solutions in both scalar and vector forms. Their versatility in emulating a range of astrophysical objects—including neutron stars, black holes, and intermediate-mass bodies—renders them a powerful tool in astrophysical modeling, allowing to explore the effect of purely gravitational entities.This paper explores the modeling of galactic DM halos using bosonic fields, extending the study initiated in [68] and addressing two open issues identified in that work. First, the previous analysis changed the properties of the vector field for each galaxy instead of treating it as a single DM candidate; and second, it introduced an additional dark component without a clear physical justification. As in [68] we employ bosonic vector fields coupled to gravity to represent the primary galactic halo, thus enhancing RC fits when combined with ordinary matter contributions.
A significant modification in the present work, which addresses the first open issue, is that we now fix the vector boson mass to a specific scale relevant to the problem, allowing only for the field frequency to vary, thereby identifying constraints on this parameter. Regarding the second issue, in [68] the extra component was introduced through an ad-hoc mathematical adjustment, lacking physical motivation and coherence across the configurations.
Here, we provide a physically meaningful explanation by employing a subhalo model consisting of a scalar bosonic field coupled to gravity to represent intermediate galactic structures. An illustration of our model is depicted in Fig. 1.
It consists of the following components: the luminous matter contribution, represented by a yellow ellipsoid (the galaxy); a quasispherical main halo formed by rotating vector bosonic matter extending beyond the galaxy, shown in dark grey; and a set of spherical subhalos modeled as scalar boson star-like structures, depicted in light grey. As we show in this paper, this model significantly improves the RC fits presented in [68], in addition to provide a physically justified framework for them.The structure of the paper is as follows: In Section II we introduce the theoretical framework for the bosonic fields we employ in our model, along with key clarifications regarding the rescalings and physical units used. Section III details how the individual contributions to the RC are obtained from both luminous and DM systems. In particular, this section discusses the model for DM subhalos under the assumption that they could be formed by a distribution of boson stars. Next, in Section IV we compare our model predictions with observational data, using the same sample of galaxies employed in [68]. This section also provides a quantitative assessment of our new model against the fits reported in [68]. A discussion of this study is presented in Section V along with our conclusions. Additional information on the equations of motion for the scalar and vector bosonic models is provided in Appendix A.
Are these models converging on the massless spin-2 graviton, with varying energies, as a dark matter particle that is really just a gravitational explanation for dark matter phenomena?
One wonders what a model with a single massive tensor dark matter particle with continuous range of masses from about 10^-26 eV to 10^-10 eV with masses distributed in something like a power law (or just an empirical estimate of the frequency of gravitational waves at each frequency which might have a lumpy and gappy distribution) fitted to the distribution of gravitational wave strengths observed by gravitational wave detectors would look like. This wide variation of graviton mass-energies is natural and expected in a graviton as dark matter candidate model.
A galaxy length wave-length would be something on the order of 10^-24 Hertz (which is basically undetectable with current gravitational wave detectors), while some rare phenomena could generate gravitational waves with much shorter wave lengths as indicated in the chart shown below from Wikipedia:
