The Lightest Neutron Star Ever? Or Something Else?

A new preprint argues that a newly observed object that looks lot like a neutron star, but is less massive than should have been possible theoretically, might be an exotic star.

But, since the observed mass, of 0.77 + 0.2 -0.17 solar masses, is still within two sigma of the theoretical minimum mass of a neutron star, which is 1.17 solar masses, I don't take the conclusion that it could be an exotic object (made up of color flavor locked quark matter), very seriously.

In other news, I have a dim opinion of any paper whose abstract begins:

The gauge singlet right-handed neutrinos are one of the essential fields in neutrino mass models that explain tiny masses of active neutrinos.

If you feel the need to create right handed neutrinos (with masses different from any of the three Standard Model active neutrinos) to explain anything, your model is probably wrong because you are too lazy to find a solution that doesn't need them, and there is no positive experimental evidence that they exist. This possibility has been a perennial source for a steady stream of dead end theoretical speculation for at least a decade or two. This paper is the work of dim bulbs in the physics community. Try harder until you come up with something better.

To be clear, I'm not saying that I'm a professional physicist coming up with something better myself. But you don't have to be a genius composer yourself to appreciate the difference between Mozart and a mediocre music theory student.

A Physics Blog Of Note (And Hiatus Note)

Manuel Urueña, physicist focused on theoretical gravitation, has an interesting physics blog entitled "Thoughts in theoretical physics" that you may want to check out. 

He has recent posts on the modified inertia formulation of MOND (particularly in light of Mach's principle), gravitomagnetism, gravitational shielding, and other physics conjectures. The blog focuses a bit more on personal conjecture and a bit less on physics "current events" than this one does, but there's nothing wrong with that.

I'm a bit out of pocket for time at the moment, so I haven't carefully analyzed any of his posts yet, but I may do so in the future. If they look good and the blog gets updated with any regularity (which if you look at my blog roll, you know that I define leniently), I may add it to my blog roll when I have the presence of mind to do that.

Also, while there is some chance that I'll post tomorrow or on Thanksgiving Day, I'll be taking a brief hiatus to take a 30th wedding anniversary trip and will be off the grid for that. But, unless my plane crashes, or I'm murdered, or eaten by wild animals, or World War III starts, or the blogger host goes out of business, I'll probably be back afterwards in due course.

Quantum Mechanics Without Feynman Diagrams

Nima Arkani-Hamed, a famous physicist, is making progress an efforts to do quantum physics calculations that are usually done with Feynman diagrams, which have a clear heuristic explanation (of assigning probabilities to all possible paths that a particle or particles can take from a starting position to an ending one), with a completely different kind of calculation, not involving infinite series that have to be approximated, that can get the same results in a subset of real world situations with less of a computational burden.

4gravitons sketches out his latest efforts in this quest.

MOND Was Right, ΛCDM Was Very Wrong, Re When Galaxies Formed

Stacy McGaugh takes a moment to emphasize that when it comes to the timing of galaxy formation, MOND was right and the ΛCDM model was profoundly wrong.

Our paper on massive galaxies at high redshift is out in the Astrophysical Journal today. This is a scientific analysis of the JWST data that has accumulated to date as it pertains to testing galaxy formation as hypothesized by LCDM and MOND. That massive galaxies are observed to form early (z > 10) corroborates the long standing prediction of MOND, going back to Sanders (1998):

Objects of galaxy mass are the first virialized objects to form (by z=10), and larger structure develops rapidly

The contemporaneous LCDM prediction from Mo, Mao, & White (1998) – a touchstone of galaxy formation theory with nearly 2,000 citations – was

present-day disc [galaxies] were assembled recently (at z<=1).

This is not what JWST sees, as morphologically mature spiral galaxies are present to at least z = 6 (Ferreira et al 2024). More generally, LCDM was predicted to take a long time to build up the stellar mass of large galaxies, with the median time to reach half the final stellar mass being about half a Hubble time (seven billion years, give or take). In contrast, JWST has now observed many galaxies that meet this benchmark in the first billion years. That was not expected to happen.

From here.

As an aside, I strongly favor naming the critical acceleration of MOND, usually notated a₀, Milgrom's Constant, after Mordehai Milgrom, who devised MOND in 1983.

A Technical But Potentially Important Conflict With The ΛCDM Model

The Cosmic Background Radiation measured by the Planck collaboration should be a lot hotter than what is observed around nearby spiral galaxies, compared to what is predicted in the ΛCDM model (a.k.a. the Standard Model of Cosmology) and is much more correlated with the ultra-large scale cosmic filament structure of the universe than the ΛCDM model predicts as well. This means a couple of things:

* The ΛCDM model has added one more problem to its dozens of existing conflicts with observational evidence. The only reasons that it is still used is that it is simple, and there is no consensus alternative.

* The inferences made from the CMB background may be subject to a pervasive source of highly significant systemic error that is not yet well understood. This could impact all sorts of cosmology "facts" based upon these systemically incorrectly measured parameters. These errors could also be a source of some key tensions in current cosmology measurements.

* The problem with trying to explain this with a physical mechanism related to dark matter is that dark matter effects are already deeply integrated into the ΛCDM model. 

We confirm at the 5.7σ level previous studies reporting Cosmic Microwave Background (CMB) temperatures being significantly lower around nearby spiral galaxies than expected in the ΛCDM model. The significance reported in our earlier work was disputed by Addison 2024, who reported lower signficances when including pixels at distances far beyond the galactic halos while disregarding pixels close to the galaxies where the main signal is seen. Here we limit the study to pixels well within the galactic halos, focus on galaxies in dense cosmic filaments and improve on signal-to-noise compared to previous studies. 

The average CMB temperature in discs around these galaxies is always much lower in Planck data than in any of the 10.000 Planck-like CMB simulations. Even when correcting for the look-elsewhere-effect, the detection is still at the 3−4σ level. We further show that the largest scales (ℓ<16) of the Planck CMB fluctuations are more correlated with the distribution of nearby galaxies than 99.99% of simulated CMB maps. 

We argue that the existence of a new CMB foreground cannot be ignored and a physical interaction mechanism, possibly involving dark matter, as well as linked to intergalactic magnetic fields, should be sought.

Frode K. Hansen, et al., "A 5.7σ detection confirming the existence of a possibly dark matter related CMB foreground in nearby cosmic filaments" arXiv:2411.15307 (November 22, 2024).

More Nazca Lines Found

So says the New York Times, and don't bring aliens into it. It took a century to find the previous 430 of them. There could be as many as 500 more yet to be rediscovered.

Hundreds More Nazca Lines Emerge in Peru’s Desert

With drones and A.I., researchers managed to double the number of mysterious geoglyphs in a matter of months.

Some 303 previously uncharted geoglyphs made by the Nazca, a pre-Inca civilization in present-day Peru dating from 200 B.C. to 700 A.D., were identified with the help of machine learning. . . . 

The Nazca people carved the designs into the earth by scraping back the pebbled, rust-colored surface to expose the yellow-gray subsoil. Little is known about the shadowy culture, which left no written record. Aside from the etchings, pretty much all that exists of the civilization are pieces of pottery and an ingenious, still functioning irrigation network.

The ancient geoglyphs have attracted theories that range from the religious (they were homages to powerful mountain and fertility gods) to the environmental (they were astronomical guides to predict infrequent rains in the nearby Andes) to the fantastical (they were landing strips and parking lots for alien spacecraft).

Dr. Sakai said that geoglyphs were drawn near pilgrimage routes to temples, which implies that they functioned as sacred spaces for community rituals, and could be considered planned, public architecture. The newly discovered geoglyphs are mainly located along a network of trails that wound through the pampa. They were most likely made by individuals and small groups to share information about rites and animal husbandry.

How Are Cosmology Based Neutrino Mass Estimates Calculated?

How are cosmology based neutrino mass estimates calculated? What conditions must hold for them to be accurate? 

A new pre-print explains:

The cosmological upper bound on the total neutrino mass is the dominant limit on this fundamental parameter. Recent observations-soon to be improved-have strongly tightened it, approaching the lower limit set by oscillation data. Understanding its physical origin, robustness, and model-independence becomes pressing. 

Here, we explicitly separate for the first time the two distinct cosmological neutrino-mass effects: the impact on background evolution, related to the energy in neutrino masses; and the "kinematic" impact on perturbations, related to neutrino free-streaming. We scrutinize how they affect CMB anisotropies, introducing two effective masses enclosing background (∑mBackg.ν) and perturbations (∑mPert.ν) effects. We analyze CMB data, finding that the neutrino-mass bound is mostly a background measurement, i.e., how the neutrino energy density evolves with time. The bound on the "kinematic" variable ∑mPert.ν is largely relaxed, ∑mPert.ν<0.8eV. 

This work thus adds clarity to the physical origin of the cosmological neutrino-mass bound, which is mostly a measurement of the neutrino equation of state, providing also hints to evade such a bound.

Toni Bertólez-Martínez, Ivan Esteban, Rasmi Hajjar, Olga Mena, Jordi Salvado, "Origin of cosmological neutrino mass bounds: background versus perturbations" arXiv:2411.14524 (November 21, 2024).