All About MOND And Dark Matter

MOND still works.

The baryonic Faber-Jackson relation (BFJR) links the baryonic mass of pressure-supported systems to their mean velocity dispersion. For elliptical galaxies, the BFJR is thought to be a projection of the fundamental plane (FP), which includes the stellar half-mass radius as a third variable. We study the BFJR and FP across eight orders of magnitude in baryonic mass, encompassing galaxy groups, ellipticals, dwarf ellipticals, and dwarf spheroidals. We compile and homogenize data for 1400 pressure-supported systems and measure their mean internal baryonic acceleration ⟨gbar⟩. 

We find that the properties of the BFJR and FP systematically depend on the internal acceleration of the sampled systems, with a transition around the acceleration scale a(0) ≃ 1.2 × 10^10 m*s^−2. For low-acceleration systems with ⟨gbar⟩ < 0.6 a(0) (dwarf galaxies and galaxy groups), the BFJR relation takes the form log(10)(M(bar)/M⊙) = (4.19 ± 0.10) log(10)(σ(los)/km*s^−1) + (2.55 +0.16 −0.16) with an orthogonal intrinsic scatter of 0.11±0.01 dex [ed. about ± 29% which is low for astronomy observations].

The FP expected from the Newtonian virial theorem is followed by high-acceleration systems (massive ellipticals with ⟨gbar⟩ ≳ 6a(0)), whereas low-acceleration systems deviate from the FP at both low masses (dwarf galaxies) and high masses (galaxy groups). 

Our results generally agree with the expectations of MOND: high-acceleration systems follow the Newtonian virial theorem in which a radial variable explicitly appears (the FP), while low-acceleration systems follow the MOND virial theorem in which the radial dependence disappears (the BFJR). On average, the MOND external field effect seems to play a secondary role in dwarf galaxies in galaxy groups and clusters.

Yong Tian, Federico Lelli, Marcel S. Pawlowski, Stacy McGaugh, Yi Duann, Kyu-Hyun Chae, Enrico Di Teodoro, Konstantin Haubner, Meng Hua Kuo, Chung-Ming Ko, "The Baryonic Faber-Jackson Relation and Fundamental Plane of Galaxy Groups, Elliptical Galaxies, and Dwarf Galaxies" arXiv:2605.26965 (May 26, 2026) (A&AL in press).

But there are dissenters, who conclude that MOND is disfavored, albeit, with a much smaller sample size, and based upon a "cored halo" model that there is not produced by any underlying dark matter physics model. 

Dwarf galaxies have long been recognised as important testing grounds for models of dark matter. For instance, it is here where the cusp-core problem is most apparent. 

In this work we select two dwarf galaxy samples: LITTLE THINGS and dwarf galaxies in SPARC. We use these to examine whether there are preferences for MOND or dark matter halos in these objects. Notably, our analysis employs the latest developments in Hamiltonian Monte Carlo sampling methodology and robust model comparison via ELPD differences. 

Our findings suggest a > 4σ preference for cored halo models over MOND. However, this relies on significant preferences from 7 out of 19 SPARC galaxies and 11 of 18 from LITTLE THINGS (few of which are overwhelming). It is notable that only a single galaxy prefers MOND over a cored halo. 

Thus, this evidence is suggestive, but does not conclusively decide against MOND. We also test for evidence of a MOND external field effect, and find weak evidence against its presence. 

Despite these statistical preferences, most SPARC galaxies remain compatible with a universal MOND scale. In LITTLE THINGS, a free MOND model is preferred to a universal value at ∼8σ, but this is of doubtful physical significance. 

For MOG, the story is different, here we find ≳8σ preferences for all halos (or MOND) against universal MOG models with significant exclusions in individual galaxies across both samples. Thus, a proposed universal rotation curve model derived from MOG is quite strongly disfavoured.

Geoff Beck, "For modified gravity, it's the LITTLE THINGS that matter" arXiv:2605.27217 (May 26, 2026).

And then, there is this attempt to explain dark matter phenomena:

We review recent results showing that, within the framework of quantum field theory in curved spacetime, the semiclassical energy-momentum tensor of the neutrino flavor vacuum fulfills the equation of state of dust and cold dark matter. By considering spherically symmetric spacetimes in the weak field approximation, the flavor vacuum is shown to contribute as a Yukawa correction to the Newtonian potential. We discuss how this modified potential provides a mechanism to account for the flat rotation curves of spiral galaxies. In this perspective, neutrino mixing is presented as a viable contributing factor to the dark matter content of the universe.

Antonio Capolupo, Salvatore Capozziello, Gabriele Pisacane, Aniello Quaranta, "Particle Physics in Curved Spacetime and Dark Matter" arXiv:2605.26134 (May 21, 2026).

Historical Genetics in Albania and Greece

While not entirely static, Albania has more continuity from the late Bronze Age to the present than the rest of the Balkans. 

Most of Europe exhibits significant continuity with the late Bronze Age at a general level, but most of Europe has also seen that mix tweaked more in the subsequent 3200 years and the shuffling has been particularly great in the Balkans which saw migratory waves from Romans, Slavs, Germanic tribes, Huns, Avars, and Ottomans in the post-Bronze Age era, leaving the Balkans in their currently ethnically fragmented state.

The history of the Albanian people has long been debated, as they first appear in historical records in the eleventh century CE and their language is not closely related to any surviving Indo-European branches. Here, to reconstruct their history, we analysed over 6,000 ancient West Eurasian genomes and 74 newly sequenced present-day ethnic Albanians. Using a range of population genetics methods, including an enhanced protocol to detect identity-by-descent segments between ancient and present-day individuals, we detect continuity of West Balkan Late Bronze and Iron Age ancestry in Early Medieval Albania, to a greater degree than in neighbouring Balkan regions. 

We find that present-day Albanians predominantly descend from this remnant palaeo-Balkan group, which by at least 800–900 CE already exhibited a genetic profile suggesting that they are ancestral to many modern Albanians. In addition, we observe geographically structured admixture with Medieval East European-related groups, averaging 10–20% across present-day Albanians. Our findings provide insight into the demographic processes shaping Albanian ancestry and help locate the origin area of the Albanian language.

Davranoglou, LR., Lauka, A., Aristodemou, A. et al. "Ancient DNA evidence for the history of the Albanians." Nat Hum Behav (May 4, 2026) (pay per view). https://doi.org/10.1038/s41562-026-02462-z

Most of Greece has a gradient of Slavic ancestry dating to the middle ages that is largest in the north and smallest in the south. The Deep Maniots (a.k.a. Inner Mani) in southern mainland Greece are an exception to the rule on the paternal side. According to this Wikipedia link:

In the early modern period, Maniots gained a reputation as fierce and proudly independent warriors, who engaged in piracy and blood feuds. They lived mainly in fortified villages and "tower houses" built as defenses against "Frankish" (see Frankokratia) and Ottoman invaders.

The Maniots claim to be descendants of the ancient Spartans and heirs to their militaristic culture. Modern observers noted Maniots' self-identification as warriors ready to "preserve their liberty" with arms. Genetic studies have identified the Maniots of Inner Mani as a population isolate within mainland Greece, showing substantial parental genetic continuity from antiquity and limited influence from medieval population movements. 

. . .

In Outer Mani, family names end in -eas, while surnames of Inner Mani end in -akis, -akos, or—less frequently—-oggonas.

The Maniot dialect in Greece rejected sound chances found in other modern Greek dialects.

[It] shared with Tsakonian and with dialects spoken around Athens until the 19th century—is the divergent treatment of historical /y/ (written <υ>). Although this sound merged to /i/ everywhere else, these dialects have /u/ instead (e.g. [ˈksulo] versus standard [ˈksilo] 'wood'). These varieties are thought to be relic areas of a previously larger areal dialect group that used to share these features, and was later divided by the penetration of Arvanitika in much of its area, in the late Middle Ages. Other features of the Maniot dialect include the palatalization of velar consonants, i.e. the realization of /k, ɡ, x, ɣ/ as ([tɕ, dʑ] or [ɕ, ʑ] before /i, e, j/. This feature is shared with many southern dialects of Greek; especially Cretan.

The Mani can, in some respects, be seen as comparable to Appalachian populations in the U.S., which share its culture of honor, its tendency to be organized in clans, its reduced admixture with outside groups, and a conservative dialect of its language (the Appalachian dialect of English is the closest living dialect of England to the Elizabethan dialect spoken in Shakespeare's era).

Notably, the founder effects seen are contemporaneous with the influx of Slavic migration into Greece (and Slavic expansion more generally), and may have been associated with a conscious resistance to and rejection of Slavic migration in the several centuries after the fall of the Western Roman Empire. Per Wikipedia:

A 2017 study found they are genetically different from other groups in the Peloponnese region. Maniot individuals share a significant amount of their genome with each other, indicating a high degree of relatedness. They are also genetically isolated from other Greek populations, though they show some overlap with people from Sicily and southern Italy. This is attributed to the Maniots having the lowest levels of Slavic genetic ancestry in the Peloponnese. Maniots from East Mani have very little Slavic ancestry (0.7–1.6%), while those from West and Lower Mani have higher, but still relatively low, amounts (4.9–10.9%). The rest of the Peloponnesian population has a higher percentage of Slavic ancestry (4.8–14.4%). 

This genetic isolation suggests that the Maniots may be descended from the ancient Dorians.

The paper and its abstract are as follows: 

The Deep Maniots, an isolated population at the southernmost tip of mainland Greece, have drawn scholarly interest for their unique dialect, culture, and patrilineal clan structure. Geographically shielded by the Mani Peninsula, they are thought to have been minimally affected by 6th-century CE migrations that transformed Balkan demography. 

To investigate their genetic origins, we analysed Y-DNA and mtDNA from 102 Deep Maniots using next-generation sequencing. Paternally, Deep Maniots exhibit an exceptional prevalence (~80%) of West Asian haplogroup J-M172 (J2a), with subclade J-L930 accounting for ~50% of lineages. 

We identify Bronze Age Greek ancestry in Y-haplogroups nearly absent elsewhere, highlighting their longstanding genetic isolation. The absence of northeast European-related paternal lineages, common in other mainland Greeks, suggests preservation of southern Greece’s pre-Medieval genetic landscape. 

Y-haplogroup phylogeny reveals strong founder effects dated to ~380–670 CE, while the emergence of clan-based social structure is estimated around 1350 CE, centuries earlier than previously thought. 

In contrast, maternal lineages display greater heterogeneity, primarily originating from ancient Balkan, Levantine, and West Eurasian sources. These results align with historical and anthropological accounts, showcasing Deep Maniots as a genetic snapshot of pre-Medieval southern Greece, offering new perspectives on population continuity and mobility in the Late Antique eastern Mediterranean.

Davranoglou, LR., Kofinakos, A.P., Mariolis, A.D. et al. "Uniparental analysis of Deep Maniot Greeks reveals genetic continuity from the pre-Medieval era." 9 Commun Biol 157 (2026) (open access). https://doi.org/10.1038/s42003-026-09597-9