What is dark matter and has it been detected?

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1. 1

   Dark matter (Wikipedia)

   WikipediaPublished Oct 3, 2026Checked Oct 4, 2026

   “In astronomy and cosmology, dark matter is an invisible and hypothetical form of matter that does not interact with electromagnetic radiation, including light. Dark matter is implied by gravitational effects that cannot be explained by general relativity unless more matter is present than can be observed. Such effects occur in the context of formation and evolution of galaxies, gravitational lensing, the observable universe's current structure, mass position in galactic collisions, the motion of galaxies within galaxy clusters, and cosmic microwave background anisotropies. Dark matter is thought to serve as gravitational scaffolding for cosmic structures. After the Big Bang, dark matter clumped into blobs along narrow filaments with superclusters of galaxies forming a cosmic web at scales on which entire galaxies appear like tiny particles. In the standard Lambda-CDM model of cosmology, the mass–energy content of the universe is 5% ordinary matter, 26.8% dark matter, and 68.2% a form of energy known as dark energy. Thus, dark matter constitutes 85% of the total mass, while dark energy and dark matter constitute 95% of the total mass–energy content.”

2. 2

   Probing dark matter interactions with a RES-NOVA prototype cryogenic detector.

   The European physical journal. C, Particles and fields (RES–NOVA)Published Sep 28, 2026Checked Oct 4, 2026

   “We report on the operation of a 13 g PbWO 4 crystal, grown from archaeological Pb and operated as a cryogenic calorimeter in an underground environment. Read out with a Ge thermistor, the detector achieves a low energy threshold and, for the first time, enables the derivation of a dark matter exclusion limit using PbWO 4 as target material, for both spin-dependent interactions on neutrons and spin-independent interactions. Although limited in mass and not representative of the final RES-NOVA detector design, this prototype demonstrates effective control of mechanical vibrations and low-energy noise in a cryogenic system, which is a key requirement for rare-event searches. The experiment therefore provides a proof of principle for the RES-NOVA detection concept, validating the use of archaeological Pb-based PbWO 4 crystals, low-background operation, and robust data-analysis procedures. These results establish a solid technological and methodological foundation for future RES-NOVA detectors employing larger target masses and advanced thermal readout technologies.”

3. 3

   First Galaxy Ultraviolet Luminosity Function Limits on Dark Matter-Proton Scattering.

   Physical review letters (Lazare et al.)Published Jul 1, 2026Checked Oct 4, 2026

   “oss section σ=σ_{0}(v/c)^{n} for n=0, 2 and 4, corresponding, e.g., to velocity-independent contact interactions from heavy mediators, velocity-dependent pseudoscalar-mediated scattering, and higher-order dipole interactions, respectively, using high-redshift (z∼4-10) ultraviolet galaxy luminosity functions (UVLFs) observed by the Hubble Space Telescope (HST). We employ an adjusted implementation of gallumi combined with the modified Boltzmann solver class dmeff that accounts for interacting DM, and incorporate UVLF data from both blank and lensed HST fields, alongside Planck CMB data and the Pantheon supernova catalog in a Bayesian analysis framework to set constraints on σ_{0}. Our results show that including lensed UVLF data, which probe fainter galaxies than the blank HST fields and thus smaller scales, leads to a substantial improvement in the constraints on σ_{0} for n>0, surpassing existing bounds from Milky Way (MW) satellite abundance and CMB anisotropies. For m_{χ}=1 MeV, for example, we set the upper bounds at 1.1×10^{-25} cm^{2} for n=2 and 2.1×10^{-22} cm^{2} for n=4. For n=0, our bound is within an order of magnitude of those from the Lyman-α forest and MW satellites.”

4. 4

   Everyone wants something better than ΛCDM.

   Proceedings of the National Academy of Sciences of the United States of America (Turner)Published Feb 13, 2026Checked Oct 4, 2026

   “The current cosmological paradigm, ΛCDM, is characterized by its expansive description of the history of the Universe, its deep connections to particle physics and the large quantities of data that support it. Nonetheless, ΛCDM's critics argue that it has been falsified or must be discarded for various reasons. Critics and boosters alike do agree on one thing: It is not the final cosmological theory and they are anxious to see it replaced by something better! I review the status of ΛCDM, provide my views on what "better" might look like, and discuss the role that the "Hubble tension" might play in moving beyond ΛCDM.”

5. 5

   Exploring exotic spin-dependent interactions beyond the standard model: theoretical foundations and experimental investigations.

   Reports on progress in physics. Physical Society (Great Britain) (Wu & Yan)Published Jul 24, 2026Checked Oct 4, 2026

   “Given their light mass and weak coupling, ALPs are also possible candidates for cold dark matter. Introducing these new interactions mediated by novel particles not only tackles several challenges in modern physics but also raises a crucial question: Are there undiscovered interactions beyond the standard model (SM)? Many of the interactions predicted by these theories are spin-dependent, which is the primary focus of this review. In this review, we first outline the theoretical foundations for investigating exotic spin-dependent interactions, highlighting their importance in various models beyond the SM. We examine the potential roles of new lightweight particles in mediating these interactions, which may enhance our understanding of dark matter. Relevant formulas derived from theoretical models are included to support experimental investigations. Following this theoretical framework, we conduct a detailed review of recent experimental efforts to detect these exotic interactions. A systematic review of current constraints on these interactions is presented, along with an assessment of various detection approaches.”