Globular Cluster Mass Scaling Relations And MaNGA DynPop Data

The MaNGA DynPop survey of nearby galaxies has just released four papers, two of which analyze a 10,000 galaxy data set, one of which looks at a 6,000 galaxy subset of that data. The last paper takes at deeper dive into the other data by combining it with other data set.

The quartet of papers were uploaded on April 23, 2023 and have been submitted to MNRAS. The papers are:

I. Quality-assessed stellar dynamical modelling from integral-field spectroscopy of 10K nearby galaxies: a catalogue of masses, mass-to-light ratios, density profiles and dark matter

This is the first paper in our series on the combined analysis of the Dynamics and stellar Population (DynPop) for the MaNGA survey in the final SDSS Data Release 17 (DR17). Here we present a catalogue of dynamically-determined quantities for over 10000 nearby galaxies based on integral-field stellar kinematics from the MaNGA survey. The dynamical properties are extracted using the axisymmetric Jeans Anisotropic Modelling (JAM) method, which was previously shown to be the most accurate for this kind of study. We assess systematic uncertainties using eight dynamical models with different assumptions. We use two orientations of the velocity ellipsoid: either cylindrically-aligned JAMcyl or spherically-aligned JAMsph. We also make four assumptions for the models' dark vs. luminous matter distributions: (1) mass-follows-light, (2) free NFW dark halo, (3) cosmologically-constrained NFW halo, (4) generalized NFW dark halo, i.e. with free inner slope. 

In this catalogue, we provide the quantities related to the mass distributions (e.g. the density slopes and enclosed mass within a sphere of a given radius for total mass, stellar mass, and dark matter mass components). We also provide the complete models which can be used to compute the full luminous and mass distribution of each galaxy. 

Additionally, we visually assess the qualities of the models to help with model selections. We estimate the observed scatter in the measured quantities which decreases as expected with improvements in quality. For the best data quality, we find a remarkable consistency of measured quantities between different models, highlighting the robustness of the results.

II. Global stellar population, gradients, and star-formation histories from integral-field spectroscopy of 10K galaxies: link with galaxy rotation, shape, and total-density gradients

We analyze the global stellar population, radial gradients and non-parametric star formation history of ∼10K galaxies from the MaNGA Survey final data release 17 (DR17), based on stellar population synthesis and full-spectrum fitting, and relate them with dynamical properties of galaxies. 

We confirm that stellar population correlates with stellar velocity dispersion σ(e) better than with stellar mass M∗, but also find that younger galaxies are more metal-poor at fixed σ(e). Stellar age, metallicity, and mass-to-light ratio M∗/L all decrease with galaxy rotation, while radial gradients become more negative (i.e., younger, more metal-poor, and lower M∗/L in the outskirts). The trend between metallicity gradients and rotation reverses for slow rotators, which stand out for their more negative metallicity gradients than faster-rotating galaxies. 

We highlight a population of massive disk galaxies on the green valley, on the (σ(e), Age) plane, that show steep negative age and metallicity gradients, consistent with their old central bulges surrounded by young star-forming disks and metal-poor gas accretion. Galaxies with high σ(e), steep total mass-density slope, low dark matter fraction, high M∗/L, and high metallicity have the highest star-formation rate at earlier times, and are currently quenched. 

We discover a population of low-mass star-forming galaxies with low rotation but physically distinct from the massive slow rotators. A catalogue of the population properties is provided publicly.

III. Accurate stellar dynamics vs. stellar population relations in 6000 early-type and spiral galaxies: fundamental plane, mass-to-light ratios, total density slopes, and dark matter fractions

We present dynamical scaling relations, combined with the stellar population properties, for a subsample of about 6000 nearby galaxies with the most reliable dynamical models extracted from the full MaNGA sample of 10K galaxies. We show that the inclination-corrected mass plane (MP) for both early-type galaxies (ETGs) and late-type galaxies (LTGs), which links dynamical mass, projected half-light radius R(e), and the second stellar velocity moment σ(e) within R(e), satisfies the virial theorem and is even tighter than the uncorrected one. 

We find a clear parabolic relation between lg(M/L)(<R(e)), the total mass-to-light ratio within a sphere of radius R(e), and lg σ(e), with the M/L increasing with σ(e) and for older stellar populations. However, the relation for ETGs is linear and the one for the youngest galaxies is constant. 

We confirm and improve the relation between average logarithmic total density slopes γT and σ(e): γT become steeper with increasing σ(e) until lg(σ(e)/kms^−1)≈2.2 and then remain constant around γT≈−2.2. The γT−σ(e) variation is larger for LTGs than ETGs. At fixed σ(e) the total density profiles steepen with galaxy age and for ETGs. 

We find generally low dark matter fractions, median fDM(<R(e))=8 per cent, within a sphere of radius R(e). However, we find that fDM(<R(e)) depends on σ(e) better than stellar mass: dark matter increases to a median fDM=33 percent for galaxies with σ(e)≲100kms^−1. The increased fDM(<R(e)) at low σe explains the parabolic lg(M/L)(<R(e))−lgσ(e) relation.

IV. Stacked total density profile of galaxy groups and clusters from combining dynamical models of integral-field stellar kinematics and galaxy-galaxy lensing

We present the measurement of total and stellar/dark matter decomposed mass density profile around a sample of galaxy groups and clusters with dynamical masses derived from integral-field stellar kinematics from the MaNGA survey in Paper~I and weak lensing derived from the DECaLS imaging survey. Combining the two data sets enables accurate measurement of the radial density distribution from several kpc to Mpc scales. 

Intriguingly, we find that the excess surface density derived from stellar kinematics in the inner region cannot be explained by simply adding an NFW dark matter halo extrapolated from lensing measurement at a larger scale to a stellar mass component derived from the NASA-Sloan Atlas (NSA) catalog. We find that a good fit to both data sets requires a stellar mass normalization about 3 times higher than that derived from the NSA catalog, which would require an unrealistically too-heavy initial mass function for stellar mass estimation. If we keep the stellar mass normalization to that of the NSA catalog but allow a varying inner dark matter density profile, we obtain an asymptotic slope of γgnfw= 1.82+0.15−0.25, γgnfw= 1.48+0.20−0.41 for the group bin and the cluster bin respectively, significantly steeper than the NFW case. We also compare the total mass inner density slopes with those from Illustris-TNG300 and find that the values from the simulation are lower than the observation by at least 3σ level.

This release has a very respectable sample size with some quite high quality data. But, digesting the analysis is non-trivial, particularly if you are looking for interpretations of it that are independent of already soundly disproven elements of the LambdaCDM model of cosmology.

Another interesting new paper (accepted for publication) looks at the scaling relations between globular cluster mass and apparent dark matter mass in galaxies:

The relation between the total mass contained in the globular clusters of a galaxy and the mass of its dark matter halo has been found observationally to be nearly linear over five decades of mass. However, the high-mass end of this relation is not well determined from previous data and shows large scatter. 

We analyze the globular cluster systems (GCSs) of a homogeneous sample of 11 brightest cluster galaxies (BCGs) through DOLPHOT photometry of their deep Hubble Space Telescope (HST) images in the F814W filter. We standardize the definition of MGCS, the total GCS mass, by using the GC total population within a limiting radius of 0.1R(virial), while the dark-matter halo mass M(h) is determined from the weak-lensing calibration of M(h) versus M(bary). 

When these 11 BCGs are added to the previously studied homogeneous catalogue of Virgo member galaxies, a total value for η=M(GCS)/M(h_ is found to be (3.0±1.8internal)×10^−5, slightly higher than previous estimates but with much reduced uncertainty. Perhaps more importantly, the results suggest that the relation continues to have a near-linear shape at the highest galaxy masses, strongly reinforcing the conclusion that accreted GCs make a major contribution to the GC populations at high galaxy mass.

Another Gravitational Theory Of Dark Matter Phenomena

Another basically gravitational explanation of dark matter and dark energy. It doesn't fully grapple with the theoretical difficulties associated with massive gravity theories in the literature, but it suffices as yet another proof of concept that it can be done.

We argue that the effect of cold dark matter in the cosmological setup can be explained by the coupling between the baryonic matter particles in terms of the long-range force having a graviton mass m(g) via the Yukawa gravitational potential. Such a quantum-corrected Yukawa-like gravitational potential is characterized by the coupling parameter α, the wavelength parameter λ, which is related to the graviton mass via mg=ℏ/(λc), that determines the range of the force and, finally, a Planck length quantity l(0) that makes the potential regular at the centre. The corrected Friedmann equations are obtained using Verlinde's entropic force interpretation of gravity based on the holographic scenario and the equipartition law of energy. The parameter α modifies Newton's constant as G(eff)→G(1+α). 

We argue that dark matter is an apparent effect as no dark matter particle exists in this picture. Furthermore, the dark energy is also related to graviton mass and α; in particular, we point out that the cosmological constant can be viewed as a self-interaction effect between gravitons. 

We further show that there exists a precise correspondence with Verlinde's emergent gravity theory, and due to the long-range force, the theory can be viewed as a non-local gravity theory. To this end, we performed the phase space analyses and estimated λ≃10^3[Mpc] and α∈(0.0385,0.0450), respectively. 

Finally, from these values, for the graviton mass, we get m(g)≃10^−68 kg, and cosmological constant Λ≃10^−52 m^−2. Further, we argue how this theory reproduces the MOND phenomenology on galactic scales via the acceleration of Milgrom a(0)≃10^−10 m/s^2

Kimet Jusufi, Genly Leon, Alfredo D. Millano, "Dark Universe Phenomenology from Yukawa Potential?" arXiv:2304.11492 (April 22, 2023).

Signs That You Are Not A Trustworthy Phenomenologist

Any paper that takes the new CDF W-Boson mass anomaly seriously should not be taken seriously as a physics phenomenologist. 

For example, it pretty much totally discredits the author of this paper in my view.

Comb Jellies Have Weird Nervous System

No other animal has a nervous system like a comb jelly, which suggests that they are in a very basal position in the animal kingdom's evolution.

Shimmering, gelatinous comb jellies wouldn’t appear to have much to hide. But their mostly see-through bodies cloak a nervous system unlike that of any other known animal, researchers report in the April 21 Science.

In the nervous systems of everything from anemones to aardvarks, electrical impulses pass between nerve cells, allowing for signals to move from one cell to the next. But the ctenophores’ cobweb of neurons, called a nerve net, is missing these distinct connection spots, or synapses. Instead, the nerve net is fused together, with long, stringy neurons sharing a cell membrane, a new 3-D map of its structure shows.

From Science News citing P. Burkhardt et al., "Syncytial nerve net in a ctenophore adds insights on the evolution of nervous systems" 380 Science 293 (April 21, 2023). doi: 10.1126/science.ade5645 

and 

A. Sebé-Pedrós et al., "Early metazoan cell type diversity and the evolution of multicellular gene regulation" Nature Ecology & Evolution (June 25, 2018) (published online) doi: 10.1038/s41559-018-0575-6

Dark Matter Phenomena Is More Wave-Like Than Particle-Like

Overview

A new paper uses a novel approach to show that dark matter phenomena is more wave-like than particle-like. It is important because it generically rules out huge swaths of the dark matter parameter space with a single set of observations.

The authors argue that this favors axion-like particle dark matter over WIMP-like dark matter without considering gravitational based sources of dark matter phenomena or other dark  matter candidates of intermediate masses. But gravitational based sources of dark matter would also be more wave-like than particle-like. 

Since the paper doesn't consider middle ground between 10^-22 eV mass axion-like dark matter particles which it models, and WIMPs of more than 10 GeV, it doesn't map out the parameter space bounds that its Einstein Ring lensing observations themselves impose, instead merely comparing two hypotheses.

My analysis below supposes a cutoff of 10 keV common associated with warm dark matter theories, because warm dark matter particle theories claim to start to overcome observational failures to cold dark matter particle theories precisely because it is at that mass scale that wave-like behavior starts to emerge.

Dark Matter Candidates More Massive Than 10 keV Are Ruled Out

This result generically disfavors dark matter candidates more massive than warm dark matter (in the single digit keV mass range), which is the most massive dark matter candidate to exhibit significant wave-like behavior. It also tilts the balance towards even lighter masses than warm dark matter, while disfavoring cold dark matter candidates in the WIMP mass range of about 1 GeV to 1000 GeV, let alone even more massive dark matter candidates that aren't effectively screened with direct dark matter detection experiments or primordial black holes. 

As the introduction to the paper notes, WIMPs (defined in the paper as having at least a 10 GeV particle mass), were already in trouble as a hypothesis:

The lightest among the stable WIMPs has long been heralded as the most likely candidate for CDM. Laboratory searches, however, have failed to detect WIMPs through direct-detection or in collider experiments. Cosmological simulations employing massive bodies to stand in for WIMPs have been highly successful at predicting the large scale structure of the universe, but face enduring problems on galactic or sub-galactic scales (< 10 kpc), the best documented of which are the “missing satellite” (along with the related “too big to fail”) and “cusp versus core” problems.

This result even largely rules out already non-viable dark matter candidates like the hypothetical X17 boson which at 17 MeV would be far too massive to have significantly wave-like behavior, in addition to being far too short lived.

Thermal Freeze Out Candidates Other Than Warm Dark Matter Are Ruled Out

Dark matter particle candidates lighter than warm dark matter (i.e. basically below 1 keV or so), since they can't be thermal freeze out dark matter particle candidates, need to be in some sort of dynamic equilibrium in which particles with very slight kinetic energy per particle are created and destroyed at the same rate. This is necessary to reflect the apparently roughly constant amount of dark matter in the universe suggested by the approximate fit of the LambdaCDM model to the astronomy data.

Since dark matter particle candidates in a thermal freeze out scenario get too "hot" (i.e. have too fast of a mean velocity) to be consistent with the amount of galaxy scale structure in the universe, any thermal freeze out dark matter candidate other than warm dark matter is essentially ruled out. 

Colder thermal freeze out dark matter candidates are ruled out because they are insufficiently wave-like.

There are other tensions with observation for warm dark matter candidates as well, many of which are shared with cold dark matter candidates, even though warm dark matter particle candidates can overcome some challenges including this one.

New Higher Energy Colliders Won't Find Dark Matter Candidates

Another important consequence of this paper is that higher energy particle colliders, which could potentially reveal beyond the Standard Model particles more massive than hundreds of GeVs, almost certainly won't reveal any new viable dark matter candidates, even if new particles are discovered in these colliders. 

Existing particle colliders are plenty powerful enough to comb the dark matter particle mass range that this study leaves in the running from zero rest mass to about 10 keV. 

The issue in this light particle mass range is escaping noise in experiments from the neutrino background to be able to see a hypothetical dark matter particle signal, not insufficient particle accelerator energy. 

Prospects For Further Research

Presumably, however, a deeper and more generalized analysis of the same data could discern whether some of the higher end of the mass range below 10 keV is also ruled out by the Einstein Ring observations.

In particular, if the Einstein Ring observations ruled out dark matter particle masses of 10 eV or more, all of the viable parameter space for sterile neutrino dark matter and warm dark matter hypotheses discussed below could be ruled out. An analysis along these lines would be a very valuable scientific contribution in service of the cause of narrowing the observationally permitted dark matter parameter space, that could extend the results of this paper with essentially the same data. This result, if established, would also completely rule out the thermal dark matter parameter space.

If this mass range was excluded, it would effectively push the parameter space for dark matter particles to below the meV order of magnitude mass range inhabited by Standard Model neutrinos. And, since we know that dark matter cannot be "hot" (i.e. have high mean particle velocity) based upon the scale of galactic structure, these particles would not only have to have a low rest mass, but would also have to have, unlike most observed neutrinos, exceeding low amounts of kinetic energy per particle (i.e. many orders of magnitude lower in mass-energy than the rest mass of the particle itself).

Standard Model Dark Matter Candidates Are Ruled Out

Hadronic Dark Matter Is Ruled Out

But high energy physics experiments have pretty well scoured nature for subatomic particles with masses of less than hundred of GeVs. The lightest hadron, the pion, is about 139 MeV (far to massive to be wave-like in addition to being too short lived). Particles with strong force color charge (i.e. quarks and gluons) are always confined in hadrons at temperatures below those that were last present in nature shortly after the Big Bang. Even the lightest quark, at about 2.5 MeV, is too massive to pass this test. While gluons theoretically have zero rest mass, their confinement into hadrons at the temperatures that have been present for the last 99.999999999999% of the universe or more, including all astronomy observations supporting the dark matter hypothesis also rule out free gluons. Also, of course, no hadrons but protons and bound neutrons are stable.

The motivation to look for ultra-heavy stable hadrons in some "island of stability" contrary to all existing indications that any heavier hadrons than those seen to date would be extremely unstable, is also undermined by the fact that any newly discovered heavy hadrons would be too massive to have predominantly wave-like behavior.

Non-Neutrino Standard Model Dark Matter Candidates Are Ruled Out

The W boson, Z boson and Higgs boson are all, of course, far too short lived and far too massive to fit the bill.

Charged leptons are obviously not dark matter candidates. Even electrons at 511 keV, in addition to being ruled out for being charged particles, are also perhaps fifty times too massive to be wave-like in the sense of this new paper's astronomy observations. The heavier muons (about 105 MeV) and tau leptons (about 1776 MeV) are also charged, are an even more poor fit due to their greater mass, and also aren't stable.

The only Standard Model particle less massive than a neutrino is the photon. A photon is stable and has zero rest mass, but we know cannot be dark matter because it is not, of course, "dark" and the aggregate amount of radiation in the universe (i.e. energy tied up in photons) is far too small to account for observed dark matter phenomena. 

Standard Model Neutrino Dark Matter Is Ruled Out

We know that dark matter is not due to Standard Model neutrinos (because it would be too "hot" and because there aren't enough neutrinos in the universe to fit the model). Also, robust cosmology estimates establish that there are only the three Standard Model  neutrino species with masses of 10 eV or less mass. 

Sterile Neutrino Dark Matter Has A Narrow Window And Is Disfavored

The experimental neutrino physics data and the observations of dark matter phenomena dynamics tends to disfavor "sterile" neutrinos, although there could be a window for sterile neutrino dark matter with particle masses greater than 10 eV and less than about 10 keV, considering this paper alone, and oscillations with ordinary neutrinos could provide a low energy dynamic process to maintain a constant aggregate mass of sterile neutrinos in the universe since a thermal freeze out mechanism wouldn't work in that mass range. There is, however, basically no credible and replicated experimental evidence for sterile neutrinos in this mass range.

If the sterile neutrino mass were below about 10 eV, this would show up in cosmology parameter estimations as addition effective numbers of neutrino species, which are robustly limited by astronomy observations to exactly three (plus an adjustment that leaves N(eff) as a non-integer value). So, light sterile neutrino species are ruled out.

But, if the sterile neutrino mass were more than 10 keV, the non-wave-like nature of the particle would rule it out based upon the Einstein Ring data.

Conjectures About Gravitons And Axions

The paper basically lumps all dark matter particle candidates with masses of much less than 1 eV into the axion-like particle category with preference for a particle mass of about 10^-22 eV. 

The introduction sums up evidence about the possible mass of axion-like particle dark matter:

While cosmological simulations involving both ϱDM and ψDM predict the same large-scale structure for the universe, ψDM naturally gives rise to characteristics observed among galaxies that pose as problems for ϱDM. 

For instance, ϱDM halos are predicted to increase dramatically in abundance toward lower masses until the Jeans limit at roughly 10^3 M, thus giving rise to the missing satellite problem. By contrast, ψDM halos are predicted to be increasingly suppressed below masses of ∼ 10^10(mψ/10^−22 eV)^−4/3 M until a cutoff at ∼ 10^7 (mψ/10^−22 eV)^−3/2 M. 

The suppression of relatively low-mass ψDM halos in the early universe provide an explanation for the apparent turnover in the abundance of galaxies toward lower luminosities at high redshifts (large cosmological distances). For mφ ∼ 10^−22 eV, λdB ranges from ∼100 pc in massive galaxies (Mh ∼ 10^11–10^12 M) to ∼1 kpc in dwarf galaxies (Mh ∼ 10^9 M), thus imposing a sizeable ψDM solitonic core in, especially, low-mass galaxies. 

The presence of solitonic cores explains why dwarf galaxies do not exhibit a cusp, a problem that can be circumvented in ϱDM only for relatively massive galaxies by appealing to feedback from star formation. 

In addition, the recently reported transition in stellar density at a radius of ∼1 kpc in local dwarf galaxies provides direct evidence for a solitonic core in these galaxies. 

Finally, a ψDM halo featuring a solitonic core can reproduce the flat stellar velocity dispersion of the ultra-diffuse galaxy DF44 that extends to about 3 kpc.

There is one almost Standard Model hypothetical particle that has strongly wave-like behavior which isn't ruled out, which is the zero rest mass graviton. 

The combined mass-energy of a graviton has been estimated, and is strikingly similar to the sweet spot for an axion-like particle dark matter mass.

The graviton's Compton wavelength is at least 1.6×10^16 m, or about 1.6 light-years, corresponding to a graviton mass of no more than 7.7×10^−23 eV/c^2.

One could say, in a quantum gravity based gravitational explanation for dark matter phenomena that dark matter (and dark energy) are basically just due to gravitons because gravity is just due to gravitons. 

Perhaps there are non-perturbative quantum gravity effects that Einstein's field equations don't capture, or the conventional GR scholarship has overlooked that could reproduce this result.

My intuition is that axion-like particle dark matter theories (which is not well motivated because the original axion motivated by a desire to explain the lack of CP-violation in the strong force has many other good explanations and doesn't really even require an explanation), to the extent that they can fit the data, do so because they have per particle mass-energy in the same ballpark as hypothetical gravitons. 

The Paper

The paper and its abstract are as follows:

Unveiling the true nature of dark matter, which manifests itself only through gravity, is one of the principal quests in physics. Leading candidates for dark matter are weakly interacting massive particles or ultralight bosons (axions), at opposite extremes in mass scales, that have been postulated by competing theories to solve deficiencies in the Standard Model of particle physics. Whereas dark matter weakly interacting massive particles behave like discrete particles (ϱDM), quantum interference between dark matter axions is manifested as waves (ψDM). 

Here, we show that gravitational lensing leaves signatures in multiply lensed images of background galaxies that reveal whether the foreground lensing galaxy inhabits a ϱDM or ψDM halo. Whereas ϱDM lens models leave well documented anomalies between the predicted and observed brightnesses and positions of multiply lensed images, ψDM lens models correctly predict the level of anomalies remaining with ϱDM lens models. 

More challengingly, when subjected to a battery of tests for reproducing the quadruply lensed triplet images in the system HS 0810+2554, ψDM is able to reproduce all aspects of this system whereas ϱDM often fails. The ability of ψDM to resolve lensing anomalies even in demanding cases such as HS 0810+2554, together with its success in reproducing other astrophysical observations, tilt the balance toward new physics invoking axions.

Alfred Amruth, "Einstein rings modulated by wavelike dark matter from anomalies in gravitationally lensed images" Nature Astronomy (April 20, 2023) https://doi.org/10.1038/s41550-023-01943-9 (Open access copy available at arxiv). 

A Notable Gravity Modification Theory

This paper has some great ideas about gravitational field self-interaction in a modest modification of General Relativity. The author has published two prior papers exploring the same theory.

Modified General Relativity (MGR) is the natural extension of General Relativity (GR). MGR explicitly uses the smooth regular line element vector field (X, - X), which exists in all Lorentzian spacetimes, to construct a connection-independent symmetric tensor that represents the energy-momentum of the gravitational field. 

It solves the problem of the non-localization of gravitational energy-momentum in GR, preserves the ontology of the Einstein equation, and maintains the equivalence principle. The line element field provides MGR with the extra freedom required to describe dark energy and dark matter. An extended Schwarzschild solution for the matter-free Einstein equation of MGR is developed, from which the Tully-Fisher relation is derived, and the gravitational energy density is calculated. 

The mass of the invisible matter halo of galaxy NGC 3198 calculated with MGR is identical to the result obtained from GR using a dark matter profile. Although dark matter in MGR is described geometrically, it has an equivalent representation as a particle with the property of a vector boson or a pair of fermions; the geometry of spacetime and the quantum nature of matter are linked together by the unit line element covectors that belong to both the Lorentzian metric and the spin-1 Klein-Gordon wave equation. 

The three classic tests of GR provide a comparison of the theories in the solar system and several parts of the cosmos. MGR provides the flexibility to describe inflation after the Big Bang and galactic anisotropies.

Gary Nash, "Modified General Relativity and dark matter" arXiv:2304.09671 (April 19, 2023) (International Journal of Modern Physics D related publication here).

More Wide Binary Data

A paper looking at new data sees a MOND effect in wide binary stars. The discussion engages with possible sources of noise or bias in the results that have been proposed in connection with earlier wide binary data, and finds those hypotheses to be implausible at best.

The Gaia eDR3 catalogue has recently been used to construct samples of nearby wide binaries to study the internal kinematics of these objects using relative velocities of the two component stars, ΔV, total binary masses, mB, and separations, s. For s≳0.035 pc, these binaries probe the low acceleration a<a(0) regime over which the gravitational anomalies usually attributed to dark matter are observed in the flat rotation curves of spiral galaxies, where a(0)≈1.2×10^10 is the acceleration scale of MOND. 

Such experiments test the degree of generality of these anomalies, by exploring the same acceleration regime using independent astronomical systems of vastly smaller mass and size. A signal above Newtonian expectations has been observed when a<a(0), alternatively interpreted as evidence of a modification in the relevant fundamental physics, or as being due to kinematic contaminants affecting the experiment; the presence of undetected stellar components, unbound encounters and spurious projection effects. 

Here I take advantage of the enhanced DR3 Gaia catalogue to perform a more rigorous and detailed study of the internal kinematics of wide binaries than what has previously been possible. Having internally determined accurate Gaia stellar masses and estimates of binary probabilities for each star using spectroscopic information, together with a larger sample of radial velocities, allows for a significant improvement in the analysis of wide binaries and careful exclusion of possible kinematic contaminants. Resulting ΔV vs. s and ΔV vs. mB scalings accurately tracing Newtonian expectations for the high acceleration regime, but consistent with the distance and mass velocity scalings observed in spiral galaxies in the low acceleration one, are obtained.

X. Hernandez, "Internal kinematics of GAIA DR3 wide binaries: anomalous behaviour in the low acceleration regime" arXiv:2304.07322 (April 14, 2023).

 

It Was Simple Before It Got Complicated

 

These guys, combined, left us with a pretty simple explanation of what the stuff in the Universe is made out of that remains perfectly adequate for a great many purposes, when combined with Newtonian gravity and mechanic's and Maxwell's equations of electromagnetism.

Almost immediately afterwards, however, we discovered quantum mechanics, neutrinos, quarks, gluons, weak force bosons, muons, tau leptons, the Higgs boson, photons, the strong force, the weak force, Special Relativity, and General Relativity, dark matter phenomena, and dark energy phenomena which made everything complicated again. 

The timing doesn't line up perfectly:

The discovery of the neutron and its properties was central to the extraordinary developments in atomic physics in the first half of the 20th century. Early in the century, Ernest Rutherford developed a crude model of the atom, based on the gold foil experiment of Hans Geiger and Ernest Marsden. In this model, atoms had their mass and positive electric charge concentrated in a very small nucleus. By 1920, isotopes of chemical elements had been discovered, the atomic masses had been determined to be (approximately) integer multiples of the mass of the hydrogen atom, and the atomic number had been identified as the charge on the nucleus. Throughout the 1920s, the nucleus was viewed as composed of combinations of protons and electrons, the two elementary particles known at the time, but that model presented several experimental and theoretical contradictions.

The essential nature of the atomic nucleus was established with the discovery of the neutron by James Chadwick in 1932 and the determination that it was a new elementary particle, distinct from the proton.

The uncharged neutron was immediately exploited as a new means to probe nuclear structure, leading to such discoveries as the creation of new radioactive elements by neutron irradiation (1934) and the fission of uranium atoms by neutrons (1938). The discovery of fission led to the creation of both nuclear power and nuclear weapons by the end of World War II. Both the proton and the neutron were presumed to be elementary particles until the 1960s, when they were determined to be composite particles built from quarks.

Newtonian mechanics and gravity (and calculus) all date to the late 1600s. 

Maxwell's equations for electromagnetism were published by 1862. Radioactivity, that would later be explained by the strong force and the weak force, had been discovered in the late 1800s.

Special Relativity (1905) (which is implicitly a part of Maxwell's equations), General Relativity (1915), and rudimentary quantum mechanics (reasonably well developed by the mid-1920s) were already in place before the neutron was discovered. 

Muons were discovered in 1936 although their place in the overall picture wasn't well understood at the time. 

Neutrinos were proposed in 1930, supported by evidence from beta decay in 1934, indirectly observed with physical evidence in 1938, and were first directly observed in 1956. 

The tau lepton was suspected in 1960 but wasn't confirmed until experiments done from 1974-1977.

Analysis Of Weak Field GR Effects In Galaxies (And MOND Still Works)

The conclusion that gravitomagnetic GR effects don't explain dark matter phenomena has been well established by multiple independent papers including Ciotti (2022). I'll look into what this paper has to say in depth once my taxes, which need to be filed or extended with payment made, are taken care of by the April 18, 2023 deadline.

It has been suggested that the observed flat rotation curves of disk galaxies can be a peculiar effect of General Relativity (GR) rather than evidence for the presence of dark matter (DM) halos in Newtonian gravity. 

In Ciotti (2022) the problem has been quantitatively addressed by using the well known weak-field, low-velocity gravitomagnetic limit of GR, for realistic exponential baryonic (stellar) disks. As expected, the resulting GR and Newtonian rotation curves are indistinguishable, with GR corrections at all radii of the order of v2/c2≈10^−6. 

Here we list some astrophysical problems that must be faced if the existence of DM halos is attributed to a misinterpretation of weak field effects of GR.

Luca Ciotti, "Rotation curves of galaxies in GR" arXiv:2304.06151 (April 12, 2023) (Proceedings of EAS2022, Symposium S3, to be published on Memorie della SAIt).

Another study, meanwhile, has found that the MOND constant threshold for "globular cluster systems is valid for early-type galaxies of all masses and . . . also applies to the red and blue sub-populations of global clusters separately", thus further extending the domain of applicability of this gravitationally based approach to dark matter phenomena.

Meanwhile, a recent attempt to fit mostly Milky Way kinematics to dark matter particle properties concludes that a neutral fermionic dark matter candidate should have a fermion mass in the ∼ 50–350 keV range, which is on the heavy side compared to previous warm dark matter theories.

Serious Problems For Fuzzy Dark Matter

Fuzzy dark matter (an axion-like particle dark matter theory) is seriously at odds with data from dwarf irregular galaxies that appear to be "dark matter dominated".

We investigate phenomenologically the viability of fuzzy dark matter (FDM). We do this by confronting the predictions of the model, in particular the formation of a solitonic core at the centre of dark matter haloes, with a homogeneous and robust sample of high-resolution rotation curves from the ``LITTLE THINGS in 3D'' catalog. This comprises a collection of isolated, dark matter dominated dwarf-irregular galaxies that provides an optimal benchmark for cosmological studies. We use a statistical framework based on Markov-Chain Monte Carlo techniques that allows us to extract relevant parameters such as the axion mass, the mass of the solitonic core, the mass of the dark matter halo and its concentration parameter with a rather loose set of priors except for the implementation of a core-halo relation that is predicted by simulations. 

The results of the fits are used to perform various diagnostics on the predictions of the model. FDM provides an excellent fit to the rotation curves of the ``LITTLE THINGS in 3D'' catalog, with axion masses determined from different galaxies clustering around m(a) ≈ 2×10^−23 eV. 

However we find two major problems in our analysis. 

First, the data follow scaling relations of the properties of the core which are not consistent with the predictions of the soliton. This problem is particularly acute in the core radius - mass relation with a tension that, at face value, has a significance ≳5σ. 

The second problem is related to the strong suppression of the linear power spectrum that is predicted by FDM for the axion mass preferred by the data. This can be constrained very conservatively by the galaxy counts in our sample, which leads to a tension exceeding again 5σ. 

We estimate the effects of baryons in our analysis and discuss whether they could alleviate the tensions of the model with observations.

Andrés Bañares-Hernández, Andrés Castillo, Jorge Martin Camalich, Giuliano Iorio, "Fuzzy dark matter confronts rotation curves of nearby dwarf irregular galaxies" arXiv:2304.05793 (April 12, 2023).

Is The Extent Of Afro-Asiatic Related To The Holocene Green Sahara?

Razib Khan has identified a fascinating new paper on African historical genetics. He notes:

- Lots of suspicion about this before. Basically, a West Eurasian-related population (admixed) was extant in the Sahara for the first half of the Holocene.

– I don’t think they’ve totally figured out Afro-Asiatic, and these results make me more open to the idea that Afro-Asiatic came from the Sahara, not less

The paper is using new modern whole genomes, together with a medium sized database of modern and ancient DNA. 

A Green Saharan era ethnogenesis for the Fulani, frames this group of nomadic pastoralists with a Moroccan origin entering North Africa from the East contemporaneously with the migration of the proto-Chadic nomadic pastoralists.

The ancestors of the Chadic people make it to Lake Chad's endorheic basin via the Yellow Nile before it was became a mere wadi by crossing the water basin divide from the source of the Yellow Nile to the Lake Chad basin around 5700 BCE (a date that can be fixed fairly precisely with archaeological dating of the appearance of human settlements on the former shores of the now greatly diminished Lake Chad).

The historical roots of the Chadic people push back the origins of Afro-Asiatic to a date no more recent than the entry of herding into North Africa, but Afro-Asiatic languages could be older than that.

Of course, one challenging aspect of this narrative for the Fulani is how the livestock that they herded could make it away from Iberia to Morocco via the Strait of Gibraltar in this early time frame (which, perhaps not coincidentally, coincides with the emergence of Bell Beaker related cultures on both sides of the strait). But given the short distance that needs to be traversed (with only line of sight navigation required), and the existence of some sort of transcontinental contacts in this region, it isn't too incredible.

Connecting the linguistics of Northeast Africa to Green Sahara era populations is challenging, however, because of subsequent language replacement in the region, leaving only substrate traces of the early Holocene linguistic makeup of the region.

The Berber languages probably date to a mostly population replacing (at least for men) expansion in an era when the Sahara was no longer green again, suggestively close in time to the appearance of the domesticate camel in North Africa. As I noted in a previous post at this blog:

The TMRCA of the Berber Y-DNA E . . . is about 3700 BCE. This would imply a male dominated migration, likely bringing the current Berber languages as well, just before the dawn of the historic era in Egypt and well after the likely ethnogenesis of the Chadic people ca. 5700 BCE whose Y-DNA TMCRA for R1b-V88 also corresponds well with the archaeologically calibrated date of origin of these peoples. This appears to be a sweet spot where Y-DNA mutation rate estimates appear to be pretty accurate.

The close similarities of the Berber language family dialects also supports the relatively recent 3700 BCE date, which would be Neolithic, rather than Mesolithic in this region. This is also about the time that the Green Sahara era that began ca. 8000 BCE ended in the region which from then on had roughly the same climate as it does today. The arid climate shift called the 5.9 kyr event peaked around 3900 BCE, and could easily have left to previous population ill adapted to survive in the new conditions, relative to the Berber migrants into the region.

The Berber expansion, which was not confined to Mediterranean coastal areas, was followed by  Phoenician influence from trading posts of this Levantine maritime civilization, followed by African Latin along the North African coast arising from Roman conquest, which in turn was followed by Arabic as the Islamic empire expanded in the 7th to 8th centuries of the common era.

Substrate influences in Western Berber languages, for example, tend to suggest that unlike most modern Afro-Asiatic languages, this substrate language was probably an ergative language. 

This is a feature shared with Sumerian, the Vasconic languages (of which Basque is the sole surviving representative), and the pre-Indo-European, pre-Afro-Asiatic, pre-Turkish languages of the highlands of West Asia. But, it is a language feature does not have its origins in the Indo-European, Afro-Asiatic, Turkish, Nilo-Saharan, Niger-Congo, or Dravidian languages, even though it is found as an apparent substrate influence in a few isolated examples of Afro-Asiatic languages.

We also know, however, that there is no trace of Caucasian/Iranian hunter-gatherer or farmer ancestry in Fulani DNA. So any genetic connection (either from Africa to Europe or from Europe to Africa) between the known European languages and the pre-Berber languages of North Africa, it is probably a link involving the Vasconic languages rather than Sumerian and/or West Asian languages.

The paper and its abstract (along with a key image from the paper) are as follows: 

Background

The Sahelian Fulani are the largest nomadic pastoral ethnic group. Their origins are still largely unknown and their Eurasian genetic component is usually explained by recent admixture events with northern African groups. However, it has also been proposed that Fulani may be the descendants of ancient groups settled in the Sahara during its last Green phase (12000-5000 BP), as also suggested by Y chromosome results.

Results

We produced 23 high-coverage (30 X) whole genomes from Fulani individuals from 8 Sahelian countries, plus 17 samples from other African groups and 3 Europeans as controls, for a total of 43 new whole genome sequences. These data have been compared with 814 published modern whole genomes and analyzed together with relevant published ancient individuals (for a total of > 1800 samples). These analyses showed that the non-sub-Saharan genetic ancestry component of Fulani cannot be only explained by recent admixture events, but it could be shaped at least in part by older events by events more ancient than previously reported, possibly tracing its origin to the last Green Sahara.

Conclusions

According to our results, Fulani may be the descendants of Saharan cattle herders settled in that area during the last Green Sahara. The exact ancestry composition of such ghost Saharan population(s) cannot be completely unveiled from modern genomes only, but the joint analysis with the available African ancient samples suggested a similarity between ancient Saharans and Late Neolithic Moroccans.

Eugenia D’Atanasio, et al., "Echoes from the last Green Sahara: whole genome analysis of Fulani, a key population to unveil the genetic evolutionary history of Africa" (April 6, 2023) https://www.biorxiv.org/content/10.1101/2023.04.06.535569

The introductory part of the body text notes that:

Among the people living in the Sahel, the Fulani, speaking a language belonging to the Niger-Congo linguistic family, represent an interesting case. They are the largest pastoral ethnic group in the world, with an estimated population of 20-40 million people settled in a broad area covering 18 African countries, from the Atlantic coast to the lake Chad basin and further east to the Blue Nile region in Sudan. Fulani are historically nomadic pastoralists, although most of them have now adopted a sedentary lifestyle based on farming. Nowadays, most Fulani live in western Africa, where the first evidence of their presence traces back to the XI century, when they settled on the Fouta Djallon highlands in central Guinea. Later, they moved eastward along the Niger river and they arrived at the lake Chad region in the XV century. Despite their recent history being relatively known, their origins are still a matter of debate. Over time, it has been proposed that their ancestors could be ancient Egyptians, Nubians, Persians, Jews, Arabs, Ethiopians or western Africans; however, the most widely accepted theories trace the Fulani origins back to ancient northern Africans or near eastern populations. 

In this context, it has also been proposed that the Fulani may be the descendants of ancient Saharan populations. Indeed, the Sahara has not always been as harsh as today: between 12,000 and 5,000 before present (BP), it was a lush and fertile environment occupied by savannah, forests and a wide hydrogeographic network of rivers and lakes. This phase, generally known as “Green Sahara”, was just the last of several alternating arid and humid phases that have characterized the geological history of this region. 

This region was inhabited by different human groups with peculiar material cultures during the last Green Sahara period, as suggested by several paleoanthropological and archeological findings, including several Saharan rock paintings as the rock art in the Tassili-n-Ajjer plateau in the Algerian Sahara, dated to 8,000 BP. Interestingly, this painting represents cattle and pastoralism rituals very similar to the ceremonies still practiced by present-day Fulani, suggesting a possible link between these people and the ancient inhabitants of the Sahara.

The ancient Saharan hypothesis about the Fulani origins seems also to be supported by some analyses of the human Y chromosome: Fulani show a high proportion of a Y lineage, i.e. E1b-M2/Z15939, dating back to the last Green Sahara. This lineage is observed at lower frequencies also in western and northern Africa, while it is absent in other sub-Saharan regions, pointing to a Green Saharan origin in the Fulani ancestors. However, other genetic data seem to give contrasting results. Considering the other human uniparental system, i.e. the mitochondrial DNA (mtDNA), Fulani harbor a non negligible proportion of Eurasian U5b and H1cb haplotypes, possibly arrived from a northern African source. As for the autosomal DNA, genome-wide studies have shown that Fulani people display both a western African component and a northern African/Eurasian one, but the estimates of such components differ across different studies and sub-groups. 

In this context, the most striking result has been obtained from the lactase locus: Fulani show a high proportion of the lactase persistence allele T-13910, that is typical of the European populations. This finding has been explained suggesting that the European lactase persistence haplotype was first introduced in northern Africa and then in the Fulani population by recent admixture with a northern African population about 2000 years ago. 

Similarly, the presence of European ancestry components on the autosomal or uniparental portions of the Fulani genome is usually explained by recent admixture between a Western or Central African source and an “Eurasian” source dating back to the last two millennia.

Despite the general agreement about the presence of a “non-western-African” component in the Fulani genome, the origin and the extent of such a component is still a matter of debate. In the last decades, the increasing number of published individuals analyzed by whole genome sequencing (WGS) has allowed to shed light on different dynamics of the populations included in such studies. However, the number of whole genomes from the African continent is disproportionately low compared to the sequences from other continents, with only few African individuals included in the main genome variation projects, despite the importance of Africa for the past and recent human history. Recently, some projects have focused on the African whole genome variability, partially filling this gap; however, only few whole genomes from Fulani individuals have been published and analyzed so far. The results from these researches confirmed the presence of a “non-western-African” component, that has been suggested to be acquired in recent times, possibly from an eastern Afro-Asiatic source; however, the contrast with data from other portions of the genome still remains and the questions about the origin and past history of Fulani people are still open.  . . . 

Later, in the discussion section, the paper lays out a Green Sahara narrative:

By comparing the Fulani genetic diversity with those of the large number of ancient individuals currently available through an admixture analysis (K=6), we observed that their non-sub-Saharan ancestry is characterized by a component observed in extremely high proportions (virtually 100%) also in ancient Morroccans older than 8000 BP, and an azure Levantine component. We could also see a non-negligible fraction of the WHG red component, as in the Late Neolithic Moroccan individuals, possibly arrived from Iberia to the Maghreb. On the other hand, Fulani lacked the Iran Neolithic/CHG blue component, which was observed instead in modern northern Africans, Middle Easterners and Europeans. 

This pattern of ancestry components can be hardly explained solely by recent admixture between western African and northern African groups. Indeed, in this case, we would have expected to observe also the Iran Neolithic/CHG blue component in the Fulani, since this component is present in all the modern northern African, European and Middle Eastern samples. 

So, the admixture event(s) that forged the non-sub-Saharan ancestry in Fulani should have occurred before the arrival of this component in the areas to the north of the Sahara. It is challenging to obtain exact time estimates for such events, considering that they were probably followed by later admixture events involving the same or very similar source populations. However, considering the results of the admixture analysis (K=6), we can try to define broad time windows. Indeed, considering the presence of the azure (Levantine) and red (WHG) components in Fulani, in addition to the orange (Iberomaurusian) one, and the absence of the blue (Iran Neolithic/CHG) component, we can postulate that their non-sub-Saharan component dates back to about 8000-7000 years ago from a source population similar (except for the blue component) to the Late Neolithic Moroccans (dated about 5000 BCE, considering their radiocarbon time estimates). In addition, the qpAdm analysis also points to a period corresponding to 7000 BP considering the radiocarbon time estimates of the two ancient sources that successfully modelled both FulaniA and FulaniB. Intriguingly, this time window corresponds to the period of the last Green Sahara. . . . 

These Saharan people may have actually been the ancestors of present-day Sahelian people, including Fulani. This is also supported by our admixture analysis, showing that also the Neolithic pastoralists from Kenya and the modern central Sahelian groups showed the orange and azure components at non-negligible proportions. Moreover, the absence of the blue component in the modern Nilo-Saharan groups from both central and eastern Sahel further confirms this hypothesis, since it has been proposed that the Nilo-Saharan languages were much more widespread in the Green Sahara region during the last humid phase, to be replaced by Afro-Asiatic languages only in more recent times (about 1500 years ago). In this context, it is also worth noting that a recent whole genome study further confirmed the presence of a shared ancestry between Fulani and Afro-Asiatic speakers from Eastern Africa. Interestingly, it has also been proposed that the Green Sahara area (more precisely the lake Chad basin, occupied by the Megalake Chad at the time) was also the homeland of the Niger-Congo (i.e. the language currently spoken by Fulani) about 7000 years ago, intriguingly corresponding to the possible time estimate of the Fulani non-sub-Saharan components. This language then spread westwards (and eastwards to a lesser extent) replacing the pre-existing languages.

The exact genetic ancestry composition of the “ghost” Saharan populations cannot be assessed without ancient individuals from that area at that time; however, on the basis of the ancient data currently available, we can propose that they were genetically similar to the Late Neolithic Moroccans here analyzed, although this group already shows the Iranian Neolithic/CHG component that was probably more diluted further south, while the yellow western African component was possibly present at higher proportions.

With the end of the Green Sahara and the subsequent gradual desertification of that region, the Saharan groups moved westwards, eastwards, southwards or northwards, as also suggested by the Y chromosome data. This phenomenon was not abrupt and was slightly longer in the central Sahel rather than in the east depending on the local hydrogeological conditions; according to the archaeological evidence, the changing climate conditions led to changes in the socio-economic organization of the different groups. In particular, it has been suggested that cattle pastoralism became the predominant form of subsistence at that time since it was a more reliable source of food, leading to the establishment of a pan-Saharan cattle cult, as testified by rock paintings and rituals that spread westwards with the pastoral groups in search of new pastures. This scenario may also reconcile the apparent contrasting evidence from different genetic systems linking Fulani with sub-Saharan, northern African, European or eastern African groups; indeed, if we assume the past presence of Green Saharan populations with extensive contacts, it is not surprising that these groups could share genetic affinities. With the Sahara desertification and the following different population dynamics, the genetic differentiation between the different groups may have led to the loss or maintenance of different genetic variants because of genetic drift and/or selection.

All this bulk of data seems to point to a Green Sahara origin of the Fulani with regard to their non-sub-Saharan component. Their ancestors were possibly Saharan cattle herders that moved westwards in response to the changing climate and then mixed with local people. Later, the peculiar Fulani lifestyle, historically characterized by nomadism and endogamy, and their population size dramatic decrease could have prevented the dilution of this ancient “Green Saharan” ancestry component that can be still identified.

Finally, both Fulani clusters show the same ancestry components, pointing to a common ancestry of the two groups, although at different proportions, suggesting different population dynamics.

Niger-Congo language speakers in the Lake Chad region around the time of the Green Sahara seem implausible. Language shift to a Niger-Congo language at a later time resulting in genetic shifts for the "Fulani B" subpopulation of the Fulani who have more West African admixture than the "Fulani A" subgroup considered, seems more likely. But the fact that both the sub-Saharan African, North African and European components of Fulani ancestry all seem to be mostly western leaning, despite some similarities with Nilo-Saharan peoples genetically (which could have happened more centrally during a Green Sahara era), does seem significant.

I discussed possible Berber linguistic origins in a 2015 blog post:

The timing and geography of the Berber expansion would be a natural fit for an Egyptian or Chadic origin to the Berber people and language. Yet, there are problems with either hypothesis.

The Berber language has much more lexical similarity to the Semitic, Chadic, and Cushitic languages than it does to ancient Egyptian (i.e. Coptic) (the Omotic languages are even less similar and do not share pastoralism related words with Afro-Asiatic languages, although they do share honey related words).

But, there is virtually no overlap between Berber Y-DNA and Chadic Y-DNA, despite the fact that the Berber ethnogenesis appears to involve a language shift driven by mass male population replacement. Y-DNA E that is dominant in the Berbers is a minor component of Semitic populations today and involves many Y-DNA clades not found in modern Berbers. And, the range of the Semitic peoples as of 3700 BCE (prior to Ethio-Semitic and Arab expansions), were remote from Berber territory relative to the Egyptians or Chadic peoples.

Several scenarios could make sense of this situation.

1. Languages in the Berber language family were widely spoken in NW Africa much earlier, perhaps from the Mesolithic era or earlier even, but when the 5.9 kyr climate event hit, one patriarchial tribe with key cultural innovations or religious fervor of some kind swept the region displacing all Berber language family dialects but their own and replacing a huge share of the male population of other Berber communities.

The Berber language family's link to other Afro-Asiatic languages may pre-date the Neolithic revolution during which Egyptian deviated lexically from other Afro-Asiatic languages due to Mesopotamian influences, but which it was strong enough to limit to word borrowing because its riverine hunter-gatherer-fisherman economy was not totally swept away by the first farmers of the Fertile Crescent as was the case in Europe, a thousand years later. The trouble with this is that Afro-Asiatic languages have a great deal of pastoral vocabulary in common suggesting post-Neolithic origins.

Also, the ergative noun case system of Berber languages, similar to Basque, Sumerian, Elamite, and Caucasian languages, and unlike all other Afro-Asiatic languages, suggests that Berber had an ergative substrate influence that was not Afro-Asiatic (as discussed below, this varies among Berber dialects in a way suggestive of possible substrate influences in NW Africa). Berber is the only ergative language in Africa (possibly also subject to caveats discussed below of a few Cushitic and Omotic languages). The only Indo-European language that is ergative, Kurdish, has a known ergative non-Indo-European substrate. . . .

Also, unlike tonality, which shows strong areal effects, ergativity appears to me to be a good index of a language's deeper relationships to other languages, which makes sense given how common phonetic changes in languages over time are generally, while fundamental grammatical changes appear to be less common.

The ergative noun case system is also inconsistent with a Nilo-Saharan or Niger-Congo linguistic substrate, despite the fact that both languages were probably present in much more of the Sahara than they are today during the Green Sahara period that preceded Berber expansion.

Thus, this scenario 1 is probably wrong. Likewise, while there may be considerable mtDNA continuity in NW Africa for 10,000 years, the Berber language and ethnicity are probably only half that old.

2. Egyptian may have been much more similar to other Afro-Asiatic languages prior to the consolidation of the Egyptian state around 3500 BCE under King Scorpion II and his immediate successor, who appears to have been very strongly influenced by Mesopotamian culture.

The Coptic language, aided by the second earliest use of writing, may have reflected a highly atypical dialect of Coptic used in his court with lots of outside influences that became a national standard as a result of his unification of the Egyptian kingdom, while the Afro-Asiatic dialects spoken in Egypt during the early Neolithic prior to his reign may have mostly been much more similar to early Semitic and Berber languages. Similar dialect standardizations around the dialect spoken in a capitol city, or by a monarch in a strong state are historically known to have occurred in England and many other nation-states.

Berber and Semitic may both descend from pre-Coptic Egyptian languages of these more typical dialects that faded away in connection with the process of state formation in a strong unified Egyptian state. NW Africa, prior to Berber expansion, perhaps starting with the Iberomaurusian archaeological culture, might have been much more strongly Iberian influenced as mtDNA data points suggest, and could have involved a European derived ergative language that arrived in the Mesolithic or early Neolithic era.

But, this ergative Iberoaurusian language was quite probably not a Vasconic one since it was probably not associated with subsequent Copper Age Bell Beaker peoples who expanded out of Iberia starting around 2900 BCE and who were the likely source of Y-DNA R1b in Western Europe. The Berbers would have arrived 500 to 1000 years earlier than the earliest signs of Bell Beaker people in North Africa, so there would have been no Bell Beaker substrate for the Berber languages of Bell Beaker influenced North Africa to absorb at the time.

The source of the Iberomaurusian is a subject of debate. A 2013 study reached the following conclusions (translated from the French original at Bernard's blog), which also suggest older dates for this culture than Wikipedia's sources assign to it:

Its lithic industry is characterized by lamellar microliths and marks a profound change from the Middle Paleolithic in the Maghreb. However, very little is known about its origin. 

Several theories have been proposed. The term itself connects Northwest Africa with Iberia. But since this proposal, archaeologists have rejected a possible link between the industry and iberomaurusienne southern Europe. Another theory proposed that the culture was iberomaurusienne after the Dabéenne culture Cyrenaica (Libya). However the dates of the iberomauruisenne Culture in Libya are newer than those in the Maghreb. More recently it has been proposed that the iberomaurusienne culture was connected to a broader phenomenon of lamellar stone industry in North Africa and the Middle East 20,000 to 23,000 years. However, this theory does not explain the greater antiquity of the iberomaurusienne Culture in North Africa and the differences between them and the stone industry in Egypt. 

Part of the problem is related to the scarcity of accurate dating. The oldest radiocarbon dates obtained for iberomaurusienne culture were obtained Taforalt: 21,900 and 21,100 years. A Tamar Hat, 7 dates were obtained between 20,600 and 16,100 years. Cyrenaica, both dating gave a value of 16,070 and 18,620 years. 

On the other hand some doubt on relations in the iberomaurusienne culture and the oldest cultures in the region. The Culture iberomaurusienne always covers the Aterian culture. However there is a debate about whether there is a temporal continuity between the two cultures, or if there is a blank period of occupation between. In Cyrenaica, iberomaurusienne culture seems to follow the Dabéenne Culture immediately. . . .

All these 54 dates provided the largest consistent set available for this period in the Maghreb. The iberomaurusienne culture and lasted about 9000 years between 21,420 and 12,698 years. In addition there is a large gap between the end of the non-Levallois industry and the beginning of the iberomaurusienne industry, about 1900 years. This non Levallois industry is different from atérienne industry that uses Levallois techniques. . . . another area of ​​the cave Taforalt included below iberomaurusienne layer and the non-Levallois layer, a layer atérienne. A date 37,570 years was obtained for this industry atérienne matching the latest timing for atérienne culture Taforalt. This dating is dating obtained Wadi Noun, south of Morocco, which gives a value of 30,900 years and the dating obtained Mugharet el Aliya, in northern Morocco, with a value of 39,000 years. Thus, Taforalt the atérienne industry is followed by a non Levallois culture, followed by the iberomaurusienne culture.

The authors then tried to connect these dating with climatic events. The recent phase of Iberomaurusian (gray sedimentary layers) is the first interstage Greenland, which is a relatively wet period. It is also interesting to see that the transition between the old and middle stages of the match Iberomaurusian to Heinrich event 1 (HE1) [Ed. a sudden global temperature decline ca. 14,000-16,800 years BP.]. Finally the end of the non-Levallois industry seems to match the 2 Heinrich event (HE2) [Ed. a sudden global temperature decline ca. 22,000-24,000 years BP.]. 

This study showed that there is no cultural continuity between iberomaurusienne industry and the one before. Thus, in the northwest of Africa the transition from the Middle Paleolithic and Upper Paleolithic corresponds to the arrival of a lamellar industry around 22,000 years driven by population growth sub-clades of mitochondrial haplogroup U6. The question is whether this event is related to the arrival of a new population in North Africa following the disappearance of the cultures of the Middle Paleolithic or not, and if it is linked to climate change.

But, this archaeological uncertainty has to be tempered by the ancient DNA evidence showing significant levels of European-like mtDNA in the region which this culture was found ca. 10,000 years ago, and the lack of strong influxes of European mtDNA or autosomal DNA in the time period from 5000 years ago onwards. The subsequent Capsian culture is the only other alternative culture in which this mtDNA could have entered the NW African gene pool. So, the odds of an Iberian connection are greatly enhanced despite the indeterminate nature of the archaeological evidence.

Thinly populated NW Africa may have had less of a capacity to hold onto its pre-existing hunter-gatherer culture in the face of Neolithic migrants than the relatively densely populated and sedentary Egyptians did as a result of the abundance of the Nile's biosphere.

Berber Y-DNA is a better match to some subset of the Egyptian mix than to the Chadic peoples, or the Semitic peoples. But, it is worth observing that the Egyptian mtDNA mix . . . is very different from that of any Berber populations. For example, there is almost no mtDNA H in Egypt, while it is common in some Berber populations. Of course, so long as one accepts that Berber expansion was male dominated, that data point isn't necessarily very informative when it comes to Berber origins.

3. The Cushitic peoples may have extended farther into the Sahara during its green period prior to the 5.9 kyr event, into areas that are now exclusively Berber or Chadic or Nilo-Saharan. Berber could have extended from a patriarchal clan at the fringe of the Cushitic range around this time. The Iberoaurusian substrate speculations of scenario 2 could apply to this scenario as well.

But, this scenario does not require such a radical remaking of the Coptic language in such short order. On the other hand, new absolute Egyptian chronologies favor unified state formation closer to 3100 BCE, rather than 3500 BCE, and puts the Neolithic to Copper Age transition around 3700 BCE in Egypt, providing more breathing room for this transition to happen while suggesting a Berber expansion technology.

Berber Y-DNA could fit as a subset of the Cushitic Y-DNA mix quite easily - the Berber clade of Y-DNA E likely had its origins in Cushitic territory.

Contrary to the ergative substrate hypothesis advanced above, it appears that there are at least a few Cushitic and Omotic langauges that are not nominative-accusative (the main alternative to ergative), although most languages in both families are nominative-accusative as are all Semitic languages. Thus, an ergative Cushitic language as a source for Berber is not necessarily impossible scenario (an Omotic language source can be ruled out linguistically from lack of lexical similarity).

But, the case for an ergative substrate influence is supported by the geographical diversity of this kind of case marking within the Berber languages. It is fully present in Morocco and Northern Algeria where the Iberomaurusian substrate was present, is only partially present in the deep Saharan Tuareg adjacent to the substrate area (perhaps due to substrate languages in the deep desert derived from the Capsian culture which was in turn derived from Iberomaurusian, but thrived in the deeper desert), and is absent in dialects in Egypt and Libya where there is no such substrate influence (although archaic words indicate that it might once have been present there). The absence of ergative case markings in Berber languages closest to the Cushitic linguistic range, and its presence most strongly in those places most distant from the Cushitic linguistic range, disfavors the hypothesis that proto-Berber was ergative prior to encountering substrate influences.

The case for the existence of a significant non-Cushitic substrate that is a source of a larger share of Berber mtDNA is also supported by the quite modest amounts of mtDNA L clades among some Berbers despite the fact that they are common place in Cushitic populations. In Morocco, for example, African mtDNA is much more common in Moroccan Arabs than in Moroccan Berbers among whom it is almost absent. Also, the immense regional variation in Berber mtDNA disfavors the hypothesis that Berber expansion was gender balanced and instead favors the hypothesis that Berbers during their expansion largely assimilated local women into their society who had deeper local geographic roots.

The scenario in 2 involving Coptic deviation from other Afro-Asiatic languages could still apply, but it could happen much more gradually (perhaps substantially in the early Neolithic as well) if the pressure of being an origin for Berber ca. 3900-3700 BCE were removed.

On balance, scenario 3 is probably more likely than scenario 2, although I can't easily rule out either scenario.

Other interesting discussions of Berber origins are found in a blog post here.