F(R) Gravity To Explain Dark Matter Phenomena

One of the most well studied variants of conventional general relativity is f(R) gravity. As the introduction to the paper below explains:

f(R) gravity is a straightforward extension of General Relativity (GR) where, instead of the Hilbert-Einstein action, linear in the Ricci scalar R, one considers a power-law f(R) = f(0n)R^n in the gravity Lagrangian. In the weak field limit, a gravitational potential is of the form:

This paper argues that this modification to general relativity can recover the baryonic Tully-Fisher relation which is also produced by MOND in the context of galaxy dynamics, but in the naturally relativistic and mathematically consistent framework of f(R) gravity (it is not the first paper to do so). The money chart is this one:

The conclusion of the paper explains that:

In this paper we use f(R) theories of gravity, particularly power-law Rn gravity, and demonstrate that the missing matter problem in galaxies can be addressed by power-law Rn gravity. Using this approach, it is possible to explain the Fundamental Plane of elliptical galaxies and the baryonic Tully-Fisher relation of spiral galaxies without the DM hypothesis. Also, we can claim that the effective radius is led by gravity and the whole galactic dynamics can be addressed by f(R) theories. Also, f(R) gravity can give a theoretical foundation for rotation curve of galaxies. We have to stress that obtained value for parameter β from galactic rotation curves or BTF differs from parameter β obtained using observational data at planetary or star orbit scales. The reason for this result is that gravity is not a scale-invariant interaction and then it differs at galactic scales with respect to local scales. 

Also, we investigated some forms of TFR in the light of f(R) gravities. These investigations are leading to the following conclusions: 

- f(R) gravity can give a theoretical foundation for the empirical BTFR, 

- MOND is a particular case of f(R) gravity in the weak field limit, 

- ΛCDM is not in satisfactory agreement with observations, 

- FP [i.e. the Fundamental Plane of elliptical galaxies] can be recovered by Rn gravity.

The paper and its abstract are as follows:

Here we use the samples of spiral and elliptical galaxies, in order to investigate theoretically some of their properties and to test the empirical relations, in the light of modified gravities. We show that the baryonic Tully-Fisher relation can be described in the light of f(R) gravity, without introducing the dark matter. Also, it is possible to explain the features of fundamental plane of elliptical galaxies without the dark matter hypothesis.

V. Borka Jovanović, D. Borka, P. Jovanović, "The baryonic Tully-Fisher relation and Fundamental Plane in the light of f(R) gravity" (April 15, 2025) arXiv:2504.11135 (Accepted for publication in Contrib. Astron. Obs. Skalnate Pleso https://doi.org/10.31577/caosp.2025.55.2.24).

Proteins In Hominin Fossil In Taiwan Are Denisovan

While the jaw bone still isn't enough to develop much of an image of what Denisovans looked like, this is definitely a major, although not unexpected, development. Denisovan admixture in modern humans had already strongly suggested a broad range for them in Asia, even though this is the first definitively identified Denisovan bone sample from comparatively warm regions in southern Asia.

A fossilized jawbone found off the coast of Taiwan more than 20 years ago belonged to a group of ancient humans, called the Denisovans, first identified in a Siberian cave.

The finding, published today in Science1, is the result of time-consuming work to extract ancient proteins from the fossil. It also expands the known geographical range of the group, from colder, high-altitude regions to warmer climates.

“I’m very excited to see this,” says Janet Kelso, a computational biologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

The lower jawbone, with four teeth intact, is called Penghu 1 and was dredged up by fishing crews from the Penghu channel, 25 kilometres off the west coast of Taiwan. Penghu 1 was donated to Taiwan’s National Museum of Natural Science in Taichung after researchers recognized its significance as coming from an ancient human relative2. But the identity of that unknown relative remained a mystery, until now.

Ancient proteins

Researchers spent more than two years carefully refining techniques for extracting ancient proteins from animal bones taken from the channel. They then used acid to isolate protein fragments from the surface of a Penghu 1 molar tooth and enzymes to extract them from the jawbone.

The team identified several degraded fragments, two of which bore specific amino-acid sequence variations matching those seen in the genetic sequences of a Denisovan finger bone3 found in the Denisova Cave in southern Siberia in 2008. The researchers could also tell that the jawbone came from a male Denisovan.

It’s the second location that molecular evidence from ancient proteins has definitively linked fossil remains to the Denisovans. The first was in a cave in Xiahe, Tibet where proteins from a jawbone4 and then a rib bone were determined to be from Denisovans.

Pinning down an exact age for the Penghu fossil is challenging because scientists do not have samples of the sediment it was buried in.

“One can only say it’s older than 50,000” years, says Rainer Grün, a geochronologist at the Australian National University in Canberra, who dated the fossil in 2015 and subsequently reanalysed the data5.

The Xiahe 1 mandible is at least 160,000 years old, and material from the Denisova cave indicates that Denisovans lived in Siberia between 200,000 and 50,000 years ago. At that time, sea levels were lower and the Chinese mainland was connected to Taiwan.

From here. 

The paper and its abstract are as follows:

Editor’s summary

Denisovans are a Pleistocene hominin lineage first identified genomically and known from only a few fossils. Although genomic studies suggest that they were widespread throughout Asia, fossils of this group have thus far only been identified from regions with cold climates, Siberia and Tibet. 

Tsutaya et al. used ancient proteomic analysis on a previously unidentified hominin mandible from Taiwan and identified it as having belonged to a male Denisovan. This identification confirms previous genomic predictions of the group’s widespread occurrence, including in warmer climates. The robust nature of this mandible is similar to that seen in a Denisovan one from Tibet, suggesting that this is a consistent trait for the lineage. —Sacha Vignieri

Abstract

Denisovans are an extinct hominin group defined by ancient genomes of Middle to Late Pleistocene fossils from southern Siberia. Although genomic evidence suggests their widespread distribution throughout eastern Asia and possibly Oceania, so far only a few fossils from the Altai and Tibet are confidently identified molecularly as Denisovan. 

We identified a hominin mandible (Penghu 1) from Taiwan (10,000 to 70,000 years ago or 130,000 to 190,000 years ago) as belonging to a male Denisovan by applying ancient protein analysis. We retrieved 4241 amino acid residues and identified two Denisovan-specific variants. The increased fossil sample of Denisovans demonstrates their wider distribution, including warm and humid regions, as well as their shared distinct robust dentognathic traits that markedly contrast with their sister group, Neanderthals.

Takumi Tsutaya, et al., "A male Denisovan mandible from Pleistocene Taiwan" 388 (6743) Science 176-180 (April 11, 2025). Hat tip to Neo in the comments.

Latest Analysis Disfavors MOND Between Wide Binaries

A new paper concludes that MOND effects are not present between wide binary stars (although not conclusively), and attributes the appearance that this is not the case the triple star systems that are mistaken for binary star systems. 

This disfavors simple toy-model MOND, but favors approaches like that of Deur and of Moffat's MOG theory, which predict MOND-like effects in galaxies but do no not predict MOND-like effects in wide binary star systems.

We provide an updated test for modifications of gravity from a sample of wide-binary stars from GAIA DR3, and their sky-projected relative velocities. 

Here we extend on our earlier 2023 study, using several updated selection cuts aimed at reducing contamination from triple systems with an undetected third star. We also use improved mass estimates from FLAMES, and we add refinements to previous modelling of the triple and other populations and the model-fitting. We fit histograms of observed vs Newtonian velocity differences to a flexible mixture of binary + triple populations with realistic eccentricity distributions, plus unbound flyby and random-chance populations. 

We find as before that Newtonian models provide a significantly better fit than MOND, though improved understanding of the triple population is necessary to make this fully decisive.

Charalambos Pittordis, Will Sutherland, Paul Shepherd, "Wide Binaries from GAIA DR3: testing GR vs MOND with realistic triple modelling" arXiv:2504.07569 (April 10, 2025).

How Small Can A Planet Be?

I support recognizing the proposed new class of "Satellite Planets."

The International Astronomical Union definitions for Planet and Dwarf Planet both require that a body has sufficient mass to overcome rigid body forces and self gravitate into a nearly round shape. However, quantitative standards for determining when a body is sufficiently round have been lacking. 

Previously published triaxial ellipsoid solutions for asteroids, satellites, and Dwarf Planets in the radius range 135 to 800 km are examined to identify a minimum mass above which the entire population, regardless of composition, is round. From this data, the minimum mass to meet the roundness criterion is 5.0 x 10E20 kg.  

The triaxial shape data suggests three radius ranges: (1) bodies with a radius less than 160 km are non-spheroidal, (2) bodies with a radius in the range 160 to 450 km are transitional in shape or nearly round, (3) bodies with a radius greater than 450 km are spheroidal. Bodies orbiting the Sun with a mass greater than 5.0 x 10E20 kg are Planets or Dwarf Planets. 

Arguments are presented for including the 16 spheroidal moons of the Solar System as a third dynamical class that can be identified as Satellite Planets. Definitions are proposed that expand upon the taxonomy started in 2006 with the International Astronomomical Union Planet and Dwarf Planet classes.

David G. Russell, "The Minimum Mass of Planets, Dwarf Planets, and Planetary-scale Satellites" arXiv:2504.07161 (April 9, 2025).

A Hypothetical Narrative Of Afro-Asiatic Origins

The Afro-Asiatic language family's origins are a hard nut to crack. This is a plausible proposal from Robert Bench.

KATRIN Neutrino Mass Result Published

Not really new, but the KATRIN experiment's upper bound on the lightest neutrino mass has fallen from 0.8 eV to 0.45 eV, as the collaboration previously noted in conference papers and preprints recounted in a June 20, 2024 post at this blog, and has now published in the scientific journal Science, according to the New York Times. 

Ultimately, the experiment should be able to reduce the upper bound on the absolute value of the lightest neutrino mass to 0.2 eV. The true value, based upon other indications like neutrino oscillation data and cosmology based measurements is probably closer to 0.001 eV. 

How Precise Are Astronomy And High Energy Physics?

* It is worth recalling that even the best telescopes often aren't very precise.

For example, the state of the art precision with which we can measure the distance from Earth to the reasonably close M87 galaxy is about ± 2-3%.

* By comparison, in high energy physics, scientists have recently detected a rare form of decay predicted by the Standard Model of Particle Physics at that frequency, from a three valence quark particle with two valence up quarks and one valence strange quark that is about 27% more massive than a proton, known as a sigma plus baryon, which accounts for just one in 100 million decays of this kind of particle, which is a tiny effect (although admittedly, the precision of that measurement is just ± 16%). 

The most recent theoretical predictions for the branching fraction B(Σ+ → pµ+µ−) lie within the range [1.2, 7.8] × 10^−8. The experimentally measured value is [0.81, 1.25] × 10^−8 derived from 237 ± 16 observed decays of sigma plus baryons to a proton, a muon, and an anti-muon.

This is the smallest baryon decay branching fraction ever definitively observed, and implicitly rules out all manner of even very slight deviations from the Standard Model of Particle Physics at the ten parts per billion level in the processes that are involved in this decay.

This branching fraction measurement took a data set of about 24 billion sigma plus baryon decays, which themselves are created in only a small fraction of the many trillions of Large Hadron Collider (LHC) particle collision events that scientists at CERN have observed to date.

* As another example, another recent paper makes a first principles calculation using lattice QCD of the absolute frequency of a certain kind of particle decay (without reference to the frequency of other possible decays of that particle), using standard world averages for the physical constants involved, and compares this prediction to two experimental measurements of the frequency of that particle decay and their average value, producing the following results:

The predicted value has been calculated to a ± 6.4% precision. The experimental measurements and their average have a ± 2.4% to 6.4% precision. 

The uncertainties in the world average measured values of the two key physical constants used in making the prediction are about 0.6% and 2% respectively, which put a floor on how precise the calculation of the predicted value in the Standard Model of Particle Physics could be. The balance of the ± 6.4% uncertainty in the predicted frequency flows from the method used to approximately calculate the true value of predicted quantity using the equations of the Standard Model of Particle Physics with lattice QCD, because these calculations can't be done exactly with current mathematical methods.

The difference between the predicted frequency and each of the two experimentally measured frequency (as well as their average value) are within one standard deviation of each other, as are the experimentally measured frequencies with each other. This is, of course, what scientific theories and experiments are suppose to do.

* In contrast, calculations made using only the electromagnetic part of the Standard Model of Particle Physics (quantum electrodynamics or QED for short) and the weak force, without implicating quantum chromodynamics (QCD), which is the physics of the strong force, and without implicating neutrino oscillations, are many orders of magnitude more precise.

* While it is not precisely on topic in this post, another article today looks at the subtle differences between a single bound state of more than three valence quarks into a composite particle known as a hadron, and a "hadron molecule" that is made up of two composite particles with two or three valence quarks each, bound to each other in a manner analogous to the way that protons and neutrons in an atomic nucleus are bound to each other, at a theoretical level.

* Finally, a new paper examines a way of approximating QCD calculations for hadrons by assigning a rest mass of 450 MeV/c^2 to gluons (which is about half the mass of a proton), rather than following the Standard Model assumption that gluons are massless, and gets some promising results. 

This is, however, simply a calculation trick. We know this because pions, which are composed of light quarks bound by gluons, have a mass of less than 450 MeV.

LambdaCDM Fails Again

LambdaCDM fails again

LambdaCDM again fails to reproduce what we observe. The latest paper below provides yet another independent case of that, based upon large scale clustering in certain kinds of dwarf galaxies, to add to the dozens of independent conflicts between LambdaCDM already identified. See, e.g., this January 25, 2021 post and this March 2, 2023 post.

The galaxy correlation function serves as a fundamental tool for studying cosmology, galaxy formation, and the nature of dark matter. It is well established that more massive, redder and more compact galaxies tend to have stronger clustering in space. These results can be understood in terms of galaxy formation in Cold Dark Matter (CDM) halos of different mass and assembly history. 

Here, we report an unexpectedly strong large-scale clustering for isolated, diffuse and blue dwarf galaxies, comparable to that seen for massive galaxy groups but much stronger than that expected from their halo mass. Our analysis indicates that the strong clustering aligns with the halo assembly bias seen in simulations with the standard ΛCDM cosmology only if more diffuse dwarfs formed in low-mass halos of older ages. This pattern is not reproduced by existing models of galaxy evolution in a ΛCDM framework, and our finding provides new clues for the search of more viable models. 

Our results can be explained well by assuming self-interacting dark matter, suggesting that such a scenario should be considered seriously.

Ziwen Zhang, et al., "Unexpected clustering pattern in dwarf galaxies challenges formation models" arXiv:2504.03305 (April 7, 2025) (Accepted for publication in Nature).

SIDM models don't solve the problem

This paper suggests that self-interacting dark matter could solve this particular problem, although the cross-section of interaction parameter preferred by this paper of 3.0 cm^2/g has already been ruled out in multiple prior studies, which constrain that cross-section of interaction to be 0.2 cm^2/g or less. 

Numerous prior papers, likewise demonstrate that SIDM has multiple serious problems of its own. See, e.g., posts on March 19, 2025 (cross-section of interaction must be under 0.2), July 25, 2023 (outliers, be they large cores or cuspy systems, are not readily accounted for), December 1, 2022 (strong correlation between visible matter and dark matter phenomena is a problem), February 2, 2022 (cross-section needs to be 0.5-1.0), August 11, 2020 (strong correlation between visible matter and dark matter phenomena is a problem), February 20, 2020 (SIDM shares the impossible early galaxies problem with LambdaCDM), November 23, 2018 (SIDM's multiple parameters fail Occam's Razor), October 23, 2017 (strong correlation between visible matter and dark matter phenomena is a problem), July 5, 2017 (strong correlation between visible matter and dark matter phenomena is a problem), December 6, 2016 (lack of DM annihilation signals rules out most SIDM models), and December 20, 2015 (cross-section should exceed 2.0 of the differences from LambdaCDM are too small). 

The literature on SIDM is obviously larger than what I discuss in these eleven posts (some of which identify the same problems or reference the same source papers). But I haven't posted too much about SIDM theories (there are 221 arXiv preprints that use the term, one of which appeared just today), in part, because they aren't very promising. Some of them, however, like a January 11, 2024 paper, and a July 12, 2023 paper place strict additional observationally derived constraints on the allowed parameter space of SIDM theories.

In general, the observational astronomy data places mutually inconsistent constraints on the cross-section of interaction in SIDM theories, can't explain the tight correlation of dark matter phenomena with visible matter distributions, can't explain outlier galaxies, doesn't produce expected dark matter annihilations, and shares the impossible early galaxies problem with cold dark matter theories.

Almost all dark matter particle theories are ruled out

In short, ΛCDM doesn't work, and SIDM doesn't work either. 

As previous posts at this blog have demonstrated based upon other papers, warm dark matter doesn't work. Primordial black holes don't work. MACHOs don't work. WIMPS don't work. And, strong force bound dark matter particles don't work.

Axion-like bosonic dark matter particles (ALP theories) with extremely small masses (comparable to the mass-energy of gravitons) aren't entirely ruled out yet, but are quite tightly constrained themselves. But this is pretty much the only remaining class of dark matter particle theories that aren't excluded.

Some gravity based explanations don't work

There are also some gravity based approaches that don't work. Ordinary gravitomagnetic effects don't get the job done, for example. And, we know that simple toy-model MOND itself is not an accurate description of reality either, even though it works and is predictive over a domain of applicability that covers almost all non-relativistic systems of galaxy size or smaller (although the wide-binary star case remains an open question and there may be problems with it far from the main plane of spiral galaxies).

But gravity based approaches (and there are far more of them out there than most people realize), at least, address one of the big problems that is generic in any dark matter particle theory, which is that dark matter phenomena are very tightly correlated with the distribution of ordinary matter in a gravitationally bound system.

Any gravity based approach which reproduced MOND effects over the entire range of single galaxies, moreover, is a good share of the way to being right. A good model, however, must, at least, also do better at being consistent with galaxy cluster phenomena. 

Conclusion: Lots of leading explanations are ruled out

In conclusion, the already established observational constraints, taken together, dramatically reduces the universe of explanations for dark matter phenomena that work, and in particular, eliminates many of the most heavily researched and mainstream explanations for it.

Sabine On Naturalness

No, Matt, this is no crisis

This is a comment on a recent video by Matt O'Dowd.

I find it extremely distressing that we are still discussing this even though it's abundantly clear that naturalness arguments have historically worked extremely badly. It's a pseudo-scientific method that physicists need to stop using.

Sabine Hossenfelder reiterates the correct observation that the physics community has wasted vast efforts on the utterly bullshit concept of "naturalness." 

A New Koide's Rule Extension Paper

A. C. Kleppe has uploaded a preprint entitled  "Quark mass matrices inspired by a numerical relation" that explores how Koide's rule for charged lepton masses can be extended to quarks. This conference paper presentation is Kleppe's first paper on arXiv and it isn't clear that the author has a university affiliation.

The abstract, after stating Koide's 1981 charged lepton mass rule (which still holds to high precision as the inputs have become more accurate over the last 44 years) states that:

Inspired by this relation, we introduce tentative mass matrices, using numerical values, and find matrices that display an underlying democratic texture.

I have discussed other attempts to make this extension and my own thoughts on it, in several previous posts at this blog. The paper does not, however, meaningfully engage with (or even mention) most of the prior literature in this area.

The statement in the paper that:

It should be noted that for the square roots of the running charged lepton masses at MZ around 91 GeV, the results no longer give the exact Koide formula.

is particularly concerning when it comes to understanding, because Koide's rule is a rule about the pole masses of particles and not about the running mass of those particles at a consistent energy scale. And, Koide's rule is, in fact, exquisitely confirmed when applied to pole masses.  

This distinction matters because the proper definition of mass to use for light quarks when extending Koide's rule is not self-evident.

The conclusion, which I have screenshotted rather than cut and paste from to preserve the integrity of the notation, states:

McGaugh On MOND Cosmology

Stacy McGaugh explores cosmology in MOND in a recent post at his blog. 

MOND struggles to fit to an expansion history of the universe, since it is just a toy model and not a full fledged relativistic theory, although it gets some things just right even without dark matter. The question of MOND cosmologies is a work in progress.

Today's Notable arXiv Papers

Astrophysicists were playful this year. HEP physicists weren't feeling the love. 

Since their domestication at the dawn of civilization, cats have been known for their uncanny ability to seemingly defy gravity. We conjecture that this innate ability of cats is real: uniquely in the animal kingdom, felis catus, possibly along with a few closely related species, are indeed capable of manipulating their passive gravitational mass. We explore this idea in the context of both general relativity and quantum physics. We reach the intriguing conclusion that a close study of the behavior of cats in a gravitational field might shed light not only on the mechanism of neutrino mass mixing but perhaps even on the most fundamental question in theoretical physics: a satisfactory unification of the theory of gravitation and quantum field theory.

Viktor T. Toth, "Feline gravity manipulation" arXiv:2503.22919 (April 1, 2025).

In the big data era of Astrophysics, the improvement of visualization techniques can greatly enhance the ability to identify and interpret key features in complex datasets. This aspect of data analysis will become even more relevant in the near future, with the expected growth of data volumes. With our studies, we aim to drive progress in this field and inspire further research. We present the second release of pastamarkers, a Python-based matplotlib package that we initially presented last year. In this new release we focus on big data visualization and update the content of our first release. We find that analyzing complex problems and mining large data sets becomes significantly more intuitive and engaging when using the familiar and appetizing colors of pasta sauces instead of traditional colormaps

PASTA Collaboration, "pastamarkers 2: pasta sauce colormaps for your flavorful results" arXiv:2503.23126 (April 1, 2025).

Any permutation-invariant function of data points r⃗ i can be written in the form ρ(∑iϕ(r⃗ i)) for suitable functions ρ and ϕ. This form - known in the machine-learning literature as Deep Sets - also generates a map-reduce algorithm. The area of a triangle is a permutation-invariant function of the locations r⃗ i of the three corners 1≤i≤3. We find the polynomial formula for the area of a triangle that is explicitly in Deep Sets form. This project was motivated by questions about the fundamental computational complexity of n-point statistics in cosmology; that said, no insights of any kind were gained from these results.

Connor Hainje, David W. Hogg, "A formula for the area of a triangle: Useless, but explicitly in Deep Sets form" arXiv:2503.22786 (April 1, 2025).

Johannes Kepler's attempt to explain the arrangement of the six innermost planets of the Solar System using his Platonic Solid Model-which postulates that planetary orbits are nested within the five Platonic solids-was ultimately unsuccessful. However, while his model failed to describe our own planetary system, Kepler was remarkably prescient in hypothesizing the existence of exoplanetary systems that might conform to this geometric framework. In this study, we analyze all known multiple exoplanet systems containing three to six planets and identify those that best match the Keplerian Platonic model. Using a semi-major-axis (SMA) ratio metric defined as the sum of squared differences between observed and theoretical semi-major-axis ratios, we find that the most well-matched three-, four-, five-, and six-planet exoplanetary systems exhibit significantly lower discrepancy values (4.38×10−6,1.05×10−2,8.21×10−2, and 2.43×10−1, respectively) compared to the inner six planets of the Solar System at 12.68. These results demonstrate that Kepler's Platonic Model is applicable to certain exoplanetary systems, suggesting that while the Solar System does not adhere to this idealized structure, other planetary systems may be governed by underlying geometric and mathematical principles akin to Kepler's vision. This study highlights the special nature of these exoplanetary systems and their potential alignment with the Platonic five-element framework.

Ji Wang, "Kepler's Platonic Model and Its Application to Exoplanetary Systems" arXiv:2503.22793 (April 1, 2025).

This paper explores an unexpected yet compelling parallel between the evolution of the universe, as described by cosmological eras, and the artistic evolution of Taylor Swift, delineated by her distinct album eras. By mapping key characteristics and transitions in the universe's history to corresponding themes and milestones in Swift's career, I offer a novel perspective on both. I culminate with predictions for Swift's future work and dare to ask a question of cosmic importance: Could Taylor Swift's thirteenth album hold the secret to the universe's ultimate destiny?

Jane C. Bright, "The Eras Tour: Mapping the Eras of Taylor Swift to the Cosmological Eras of the Universe" arXiv:2503.22795 (April 1, 2025).

Understanding our place in the universe is an eternal quest. Through the analysis of the 3D structures of 66 nearby open clusters using Gaia DR3 data, we discovered an intriguing pattern: most clusters show their elongation directions pointing at the Sun, suggesting that the Solar System might just be the universe's favorite spot, a cosmic feng shui hotspot! This surprising result hints at a subtle blend of geometry and geomancy.

Lu Li, Zhengyi Shao, "On the structure of open clusters: geometric vs geomantic" arXiv:2503.22800 (April 1, 2025).

We present a novel and somewhat whimsical approach to pulsar hotspot modeling by drawing inspiration from the iconic one-eyed monster, Mike Wazowski, from Monsters, Inc. Utilizing X-ray high-quality timing data from NICER, we apply a Bayesian inference framework to model the X-ray pulse profile of PSR J0437--4715. Our analysis employs a Wazowski Configuration (WC) in which the conventional hotspot parametrization is replaced with a predefined image template, whose redness and size are adjusted to mimic temperature variations. The results reveal a configuration where two hotspots--one brighter and smaller in the north represents the energetic ``University time Wazowski", and one larger yet cooler in the south represents the ``Monster, Inc. time Wazowski"--combine to produce the observed X-ray pulse profile. These findings not only demonstrate the sensitivity of pulse profile modeling to hotspot morphology but also open up the intriguing possibility that the X-ray emission of some pulsars may be interpreted as a cosmic homage to our favorite animated character.

Chun Huang, "The Cosmic One-Eyed Smile: Revealing the Hidden Face of Mike Wazowski" arXiv:2503.22914 (April 1, 2025) (Submitting to Monster University Journal).

Cookies are enjoyed best when they are both crispy and soft. I investigate in which proportion the cookies are crispy and soft, and disentangle whether it makes them biscuits, cakes, or none of the above. I baked cookies for colleagues at KTH, Stockholm, and University of Geneva, Switzerland, adopting my mum's mum's mum's etc. recipe. I created a dedicated survey for my colleagues with three well-selected questions to answer while eating one cookie. The weighted-average mean of the crispiness and softness, weighted by the respective enjoyment of the cookie, over the whole population amount to 7.0 +/- 1.1 and 5.3 +/- 1.4, respectively. The enjoyment of the cookies amounts to 9.1 +/- 2.3. People like (my) cookies, and cookies are neither cakes, nor biscuits, they are just... cookies!

Sophie Rosu, "All about Cookies: The perfect compromise between softness and crispiness" arXiv:2503.23114 (April 1, 2025).

Catsteroseismology, or asterocatsmology, is an unexplored area of observational and theoretical research that proposes to use purr-mode oscillations to study the much-beloved but poorly-understood species Felis catus. In this work, we conduct a survey to measure fundamental purrameters of cats and relate them to their purr-modes. Relations between these fundamental cat purrameters, which include physical (eg. size, cuddliness) and personality (eg. aggression, intelligence) traits, and purr-modes can help probe their inner lives and emotions. We find that while purr characteristics tentatively trend with several physical and personality traits, more data is required to better constrain these relationships and infer the direct predictive power of personality on purr-modes, or vice versa.

Rae Holcomb, Christopher Lam, "Catsteroseismology: Survey-based Analysis of Purr-mode Oscillations Suggests Inner Lives of Cats are Unknowable" arXiv:2503.23560 (April 1, 2025).

We report the detection of whisky in the atmosphere of the extrasolar super-Earth planet GJ 1132b from transmission spectroscopic data. It is seen both in atmospheric absorption as well as in chromospheric emission, the latter probably due to the intense heating of the co-rotating planet's day-side surface. This detection cannot be explained using natural sources of alcohol, implying that there must be a technically advanced civilisation -- possibly originating from the neighboring habitable planet GJ 1132c -- that is engaged in massive distilling operations accompanied by high levels of industrial pollution. The reason for the necessarily vast scale of production is either to produce rocket fuel for an interplanetary economy or, more likely, for an unusually high level of personal consumption. The latter hypothesis suggests a novel explanation for the Fermi Paradox (the lack of indirect or direct contact with extraterrestrials): a technically versed civilisation would be incapable of achieving the higher technical levels necessary for the development of a detectable radio signature -- much less interstellar travel -- at the suggested rates of consumption.

Frederic V. Hessman, Andrew Collier Cameron, Keith Horne, "Detection of an extraterrestrial technical civilisation on the extrasolar planet GJ 1132b" arXiv:2503.23788 (April 1, 2025).

High angular resolution holds the key to extending our knowledge in several domains of astronomical research. In addition to the development of new instruments, advancements in post-processing algorithms can enhance the performances attainable in an observation, turning archival observations into a treasure. We developed a machine-learning tool, named zoom-in, that is able to improve the angular resolution of an astronomical image by a factor of ∼100 by optimally recombining short-cadence sequences of images. After training our model on real-life photographs, we tested our method on archival images of the Moon taken through ESO instruments. We were able to achieve a remarkable spatial resolution of ∼1 m of the lunar surface. While analyzing one of the fields from the sample, we discovered structures of clear anthropic origin inside the Aristarchus crater. The features appear to be consistent with ancient ruins of cities and castles. A thorough analysis of the relevant literature allowed us to conclude that this valley corresponds to the one described in Ludovico Ariosto's "Orlando Furioso": a place where all the items lost by humans gather and pile up. Analyses of the surface brightness from our images, indicating an abnormally high albedo of ∼0.25, further corroborate this idea suggesting a conspicuous presence of glass. We infer the presence of >1 billion flasks of human wits on the lunar surface, whose origin we investigate in detail. We urge for a dedicated mission, astolfo, to be carried out by Artemis astronauts in order to recover human wits and bring them back to the Earth.

Vito Squicciarini, Irina Mirova, Francis D. Anderson, Zhiyuan He, Wahman al-Khwarizmi, "Orlando's flask: detection of a lost-and-found valley on the Moon" arXiv:2503.24242 (April 1, 2025) (Submitted for publication on 1st April 2025 to the prestigious journal Acta Prima Aprilia).

The cosmological principle posits that the universe does not exhibit any specific preference for position or direction. However, it remains unclear whether the universe has a distinct preference for parity: whether certain properties are more likely to be classified as even or odd. In this study, we analyze the largest available galaxy group catalogs to explore this hypothesis: specifically, whether the number of galaxies within a galaxy group or cluster is more likely to be odd or even. Our findings convincingly indicate that the universe indeed favors odd numbers, with results achieving a significance level well above the 4.1−σ threshold.

Shiyin Shen, Nan Li, "The Universe is Odd" arXiv:2503.22839 (April 1, 2025) (This manuscript is deliberately announced on an odd-numbered date).

For generations, people have complained that things used to be better in the past. In this paper, we investigate this change by specifically looking at creativity in astronomy. To do this, we explore if older constellations reflected a greater sense of creativity on the part of those designing them than more modern constellations do. We find that things really have become simplistic and less original over time.

Michael B. Lund, "Astronomers Getting Less Creative Over Time Is Why This Title Isn't Better" arXiv:2503.23614 (April 1, 2025) (submitted to Acta Prima Aprilia).

We all love the ecstasy that comes with submitting papers to journals or arXiv. Some have described it as yeeting their back-breaking products of labor into the void, wishing they could never deal with them ever again. The very act of yeeting papers onto arXiv contributes to the expansion of the arXiverse; however, we have yet to quantify our contribution to the cause. In this work, I investigate the expansion of the arXiverse using the arXiv astro-ph submission data from 1992 to date. I coin the term "the arXiverse constant", a0, to quantify the rate of expansion of the arXiverse. I find that astro-ph as a whole has a positive a0, but this does not always hold true for the six subcategories of astro-ph. I then investigate the temporal changes in a0 for the astro-ph subcategories and astro-ph as a whole, from which I infer the fate of the arXiverse.

Joanne Tan, "Written in the Stars: How your (pens and) papers decide the fate of the arXiverse" arXiv:2503.23957 (April 1, 2025) (Published in the 2024 issue of Acta Prima Aprila. An arXiv resubmission after a year).

I report the discovery of jacquetium (0Jq), the first naturally occurring element found since more than 80 years.

Emmanuel Jacquet, "Jacquetium, a new, naturally-occurring chemical element" arXiv:2503.24030 (April 1, 2025) (Submitted to the Journal of Improbable Science, 2025 yearly (April 1) issue).

The field of astronomy evolves rapidly, and it is essential to keep up with these changes in order to effectively communicate with the broader community. However, communication itself also changes as new words, phrases, and slang terms enter the common vernacular. This is especially true for the current youngest generations, who are capable of efficiently communicating via the Internet. In order to maintain effective communication, we explore the possibility of expanding the language used in scientific communication to include recently coined slang. This attempt at outreach, while potentially very difficult, could provide a means to expand the field and capture the attention of early-career scientists, improving retention within the field. However, our results indicate that, while possible, this method of communication is, like, probably not really worth it, no cap.

Anne E Blackwell, David L Moutard, Jake A Miller, "The Rizzeta Stone: Adopting Gen-α Colloquial Language to Improve Scientific Paper Rizz and Aura from a Skibidi Perspective" arXiv:2504.00073 (April 1, 2025).

The spherical cow approximation is widely used in the literature, but is rarely justified. Here, I propose several schemes for extending the spherical cow approximation to a full multipole expansion, in which the spherical cow is simply the first term. This allows for the computation of bovine potentials and interactions beyond spherical symmetry, and also provides a scheme for defining the geometry of the cow itself at higher multipole moments. This is especially important for the treatment of physical processes that are suppressed by spherical symmetry, such as the spindown of a rotating cow due to the emission of gravitational waves. I demonstrate the computation of multipole coefficients for a benchmark cow, and illustrate the applicability of the multipolar cow to several important problems.

Benjamin V. Lehmann, "Higher multipoles of the cow" arXiv:2504.00506 (April 1, 2025) (No cows were harmed).

We present the first--ever example of a macroscopic system in a quantum superposition. The system in question is a Siamese cat known as Lola; however, on a time scale of about 12 hours it oscillates into a different state that we refer to as "Mola". In the "Lola" state, the system is sweet and friendly and allows to cuddle itself, but in the "Mola" state, it is malevolent and witchy. When the probability of the system being in the "Mola" state is high, decoherence is strongly discouraged!

Harman Deep Kaur, Mariagrazia Trapanese, Kirill Zatrimaylov, "Macroscopic "Lola/Mola" Cat State" arXiv:2503.23433 (April 1, 2025).