The knee in the cosmic ray spectrum has long been hypothesized as a signature of the limit to which conventional cosmic accelerators could energize particles, marking a transition from one power-law regime to another. Yet, definitive evidence connecting this feature to specific astrophysical sources remained elusive—until now. Published in leading journals National Science Review and Science Bulletin, two comprehensive studies led by an international consortium of researchers have identified micro-quasars powered by black hole accretion systems as the prime candidates behind this cosmic phenomenon. These compact high-energy sources operate within the Milky Way and produce particle acceleration previously underestimated in galactic models.

Micro-quasars are formed when black holes in binary star systems siphon material from their companions, triggering relativistic jets capable of accelerating particles to ultra-high energies. Utilizing the unparalleled sensitivity and hybrid detection capabilities of LHAASO, scientists achieved the first systematic observation of ultra-high-energy gamma rays emanating from five notable micro-quasars: SS 433, V4641 Sgr, GRS 1915+105, MAXI J1820+070, and Cygnus X-1. These gamma emissions provide a direct window into the presence of PeV-energy protons and other cosmic particles energized by black hole jet systems.

Especially striking were the findings related to SS 433, where gamma radiation spatially coincides with a massive ambient atomic cloud. This overlap signifies that particles accelerated by the black hole are interacting with surrounding matter, thereby producing gamma rays via hadronic collisions. Intriguingly, the proton energies in SS 433 exceed 1 PeV, with an astounding power output on the order of 10^32 joules per second—energy comparable to the detonation of four trillion powerful hydrogen bombs every second. Similarly, V4641 Sgr exhibited gamma rays reaching 0.8 PeV, categorizing it as a super PeV particle accelerator with parent particles surpassing 10 PeV in energy.

These discoveries profoundly challenge the traditional paradigm that supernova remnants are the exclusive sources of galactic cosmic rays. While supernova remnants do contribute to cosmic ray acceleration, both observational data and theoretical models assert their incapacity to reach energies beyond the knee. The LHAASO observations reposition micro-quasars as vital agents capable of not only reaching but exceeding the knee threshold, thereby filling a critical gap in cosmic ray origin theories.

A major technical hurdle overcome by LHAASO was the precise measurement of the proton energy spectrum in the PeV region. Detecting cosmic ray protons at these extreme energies is inherently difficult due to their rarity and the interference introduced by the Earth’s atmosphere in ground-based observatories. Furthermore, satellite-based cosmic ray detectors possess limited collection areas, restricting their effectiveness at ultra-high energies. Through a novel multi-parameter measurement approach and rigorous statistical selection of a high-purity proton sample, LHAASO achieved precision rivaling satellite measurements, revealing a complex spectral structure characterized by an unanticipated high-energy component superimposed on existing power-law distributions.

Integrating LHAASO’s findings with those from space-borne experiments such as AMS-02 and DAMPE, scientists have recognized multiple, discrete acceleration sources within the Milky Way, each imprinting distinct spectral features on cosmic rays. This multiplex acceleration model elucidates the knee as the energy boundary of the most potent accelerators—in this case, black hole-driven micro-quasars—rather than a singular universal cutoff. This nuance significantly redefines the cosmic ray landscape and provides essential context for interpreting high-energy particle flux variations observed on Earth.

The enriched understanding emerging from these studies emphasizes that the cosmic ray proton flux in the PeV range is dominated by contributions from micro-quasars, with acceleration capabilities far surpassing those of supernova remnants. This hierarchical structuring implies that while supernova remnants provide the bulk of lower energy cosmic rays, micro-quasars furnish the extreme high-energy particles responsible for the knee, thereby offering a more comprehensive explanation compatible with observational spectra.

Together, the discoveries of micro-quasar gamma-ray emissions and the refined proton energy spectrum measurement combine into a compelling narrative that not only resolves the knee’s origin but also illuminates the role of black holes as astrophysical particle accelerators. This breakthrough provides a critical observational anchor for theoretical models that have long suggested relativistic jets as engines of extreme particle acceleration, cementing black hole systems as fundamental contributors to the high-energy cosmic environment.

LHAASO’s multidetector, hybrid array methodology, which simultaneously observes cosmic ray sources through ultra-high-energy gamma rays and performs localized cosmic ray particle measurements near Earth, represents a revolutionary approach. This dual capacity allows unprecedented cross-validation of acceleration processes and spectral signatures, linking distant astrophysical phenomena with terrestrial detection data. For the first time, observational evidence directly associates the knee structure with a distinct category of astrophysical accelerator—black hole jet systems—sharpening our ability to map cosmic origins.

Conceived, designed, and operated by Chinese scientists, LHAASO embodies cutting-edge technology in high-energy particle astrophysics. Its sensitivity to both gamma-ray astronomy and cosmic ray measurement has enabled a suite of globally impactful discoveries over recent years, pushing the frontiers of knowledge regarding extreme physical processes in the universe. With these latest contributions, LHAASO cements its position at the forefront of cosmic ray research, enabling deeper exploration into the mechanisms shaping the high-energy cosmos.

Moreover, the implications of this research extend beyond cosmic ray physics, touching fundamental questions about black hole accretion, jet formation, and particle acceleration mechanisms under extreme gravitational and magnetic fields. As micro-quasars now emerge as key astro-particle laboratories, further observations will refine particle acceleration models and potentially unravel connections between cosmic rays and other high-energy astrophysical phenomena such as neutrinos and gravitational waves.

This paradigm-shifting work underscores the power of international collaboration and state-of-the-art observatories in resolving astrophysical puzzles once considered intractable. As cosmic ray research progresses, the integration of multi-messenger astronomy and next-generation instrumentation will undoubtedly build upon the foundation established by LHAASO’s groundbreaking findings, ushering a new era of discovery in high-energy astrophysics.

Subject of Research: Cosmic ray origins and high-energy particle acceleration by micro-quasars

Article Title: [Not explicitly provided in the content]

News Publication Date: 16-Nov-2025

Web References: http://dx.doi.org/10.1016/j.scib.2025.10.048

Image Credits: LHAASO Collaboration

Keywords

Cosmic rays; Micro-quasars; Black hole accretion; Ultra-high-energy gamma rays; Particle acceleration; PeV cosmic rays; LHAASO observatory; Astroparticle physics; Galactic cosmic ray sources

Dark matter has remained one of the most confounding enigmas in modern astrophysics and cosmology. Though its gravitational effects are observed on galactic and cosmological scales, dark matter itself has never been directly detected in controlled laboratory experiments. This scarcity of direct evidence drives scientists to seek alternative probes. The study led by graduate student Mehrdad Phoroutan-Mehr delves into the interaction between dark matter and gas giant exoplanets, particularly those comparable in mass and size to Jupiter.

The researchers theorize that over extended time frames, dark matter particles could be gravitationally captured by these massive gaseous planets. Through a process involving energy loss and gravitational settling, these particles would accumulate within the planetary cores. The key insight of the study arises under the assumption that dark matter particles are superheavy and non-annihilating—meaning they do not destroy each other upon contact, a departure from conventional models where dark matter particles annihilate when colliding.

Phoroutan-Mehr explains that if such superheavy dark matter particles exist and congregate densely in the core of an exoplanet, their mass could reach a critical threshold, prompting gravitational collapse into a microscopic black hole. Remarkably, this nascent black hole could consume the host planet from within, effectively converting the entire planet into a black hole of planetary mass. This phenomenon, while hypothesized, challenges existing paradigms dictating that black holes must be formed with masses far exceeding that of planets, typically through stellar collapse or primordial origins in the early universe.

The implications of this mechanism are profound. If gas giant exoplanets in regions of our galaxy enriched with dark matter—such as the galactic center—could harbor or evolve into small black holes, astronomers might observe detectable signatures indicative of this process. Of particular interest is the timescale over which black hole formation could occur, which the study argues might be within observable durations, especially for exoplanets with varying sizes, temperatures, and internal densities.

This paradigm also introduces a novel methodology for dark matter detection. Traditionally, astrophysical probes focus on stars—like our Sun—or compact objects such as neutron stars and white dwarfs, each offering distinct environments where dark matter interactions manifest in measurable ways. For instance, prior work explored how dark matter could induce heating effects in neutron stars. However, exoplanets have received less attention due primarily to limited observational data until recent years.

Exoplanet surveys have expanded dramatically with missions like Kepler and TESS, yielding a treasure trove of data on thousands of planetary bodies across diverse stellar systems. Future missions promise even more precise characterization of exoplanet properties. Leveraging this expanding dataset, scientists may begin to identify anomalies or indirect hints pointing toward dark matter’s influence by closely examining planetary atmospheres, thermal emissions, or even gravitational effects attributed to a hidden black hole core.

Phoroutan-Mehr also highlights that the absence of detected planet-sized black holes in known exoplanetary systems provides valuable constraints on dark matter models, ruling out some variants while refining parameters for others. Specifically, if exoplanets have not collapsed into black holes over billions of years, this may disfavor certain superheavy non-annihilating dark matter scenarios, tightening the theoretical landscape.

In addition to black hole formation, the study discusses other potential effects of dark matter on planetary bodies. Superheavy dark matter particles, as they traverse an exoplanet, could deposit energy, subtly heating the planet or inducing high-energy radiation emissions. While current detection technologies lack the sensitivity to observe such faint signals directly, next-generation space telescopes and observatories may achieve the necessary precision to detect these signatures, adding another tool in the quest to uncover dark matter’s nature.

Furthermore, the prospect of planet-size black holes stands as a tantalizing target for observational astrophysics. Until now, black holes detected have exhibited masses ranging from those of stars to millions or billions of times that of the Sun. Finding a black hole comparable in mass to Jupiter would defy conventional astrophysical formation theories and provide compelling evidence for exotic dark matter accumulations—offering a breakthrough in both particle physics and cosmology.

The research underscores a crucial shift in dark matter investigations from terrestrial labs and large astrophysical objects to distant, smaller planetary bodies, expanding the parameter space and observational strategies scientists can employ. This multidisciplinary approach interweaves planetary science, astrophysics, and particle physics, demonstrating the exciting intersections driving new discoveries.

Looking ahead, the team advocates for intensified exoplanet observations focusing on regions enriched with dark matter density, supplemented by refined theoretical modeling to predict observable phenomena indicative of dark matter capture and collapse. Should evidence emerge confirming the presence of black holes formed inside exoplanets or detect anomalous heating related to dark matter, these findings would profoundly influence our understanding of the cosmos and the fundamental building blocks of matter.

In conclusion, this innovative study opens a promising frontier in dark matter research, positioning exoplanets as natural detectors for one of physics’ greatest mysteries. As data grows richer and observational capabilities improve, these distant planetary systems might reveal secrets that have eluded scientists for decades, transforming speculative theory into empirical science and reshaping humanity’s cosmic perspective.

Subject of Research: Not applicable

Article Title: Probing superheavy dark matter with exoplanets

News Publication Date: 20-Aug-2025

Web References:
https://journals.aps.org/prd/abstract/10.1103/qkwt-kd9

References:
Phoroutan-Mehr, M., & Fetherolf, T. “Probing Superheavy Dark Matter With Exoplanets,” Physical Review D, DOI: 10.1103/qkwt-kd9

Image Credits: Mehrdad Phoroutan-Mehr

Keywords

dark matter, exoplanets, superheavy dark matter, black hole formation, planetary black holes, astrophysics, cosmology, dark matter detection, non-annihilating dark matter, UC Riverside, particle astrophysics

Black holes have long captivated the minds of scientists and the public alike. These regions of spacetime are characterized by gravitational forces so intense that nothing, not even light, can escape their grasp. According to general relativity, when a star collapses under its own gravity to form a black hole, it creates a singularity—a point of infinite density where the laws of physics as we know them cease to operate. For decades, this understanding of black holes has remained largely unquestioned, framing them as endpoints rather than gateways within the cosmos.

However, the new research led by Dr. Steffen Gielen and co-author Lucía Menéndez-Pidal challenges this foundational view by suggesting that the singularity doesn’t signify an end, but rather a transition point that could lead to something entirely new—a white hole. Unlike their dark counterparts, white holes are theorized to create matter and energy, effectively "spitting" them back into the universe. If validated, this notion would not only extend our conception of black holes but could also have significant implications for our understanding of cosmic evolution.

The research hinges on the fundamental tenets of quantum mechanics, particularly the behavior of particles at the atomic level and below. The unfolding theories suggest that our understanding of time must also evolve in parallel with these insights. Traditional views often depict time as linear and absolute, but Gielen’s work posits that time could be a dynamic entity shaped by the very dark energy thought to be responsible for the universe’s acceleration. To think of time in this way could reshape how we comprehend events at cosmological scales and enable us to construct a model in which time itself may emerge from complex energy interactions.

In the peer-reviewed paper titled "Black Hole Singularity Resolution in Unimodular Gravity from Unitarity," published in Physical Review Letters, the researchers utilize a theoretical framework that employs a simplified planar black hole model. This model departs from the conventional spherical black hole structure, featuring a flat, two-dimensional boundary that facilitates the analysis of gravitational and energy interactions more flexibly. Their findings suggest that similar dynamics could also be at play within the classic spherical black hole paradigm, marking a significant shift in how we perceive these space-time anomalies.

The implications of a white hole could be staggering. If the theoretical model holds true, it might allow for a resolute connection between what we perceive as a singularity and a new phase of existence beyond it. Imagine a hypothetical observer traveling through the black hole, emerging from a white hole where the traditional understanding of time and space breaks down entirely. In this other dimension, time could be liberated from its conventional constraints, offering new insights into how the universe functions on a fundamental level.

Current theories surrounding dark energy suggest that it constitutes approximately 68 percent of the universe, a mysterious force that accelerates the expansion of the cosmos. Gielen proposes that time itself can be measured against this dark energy, thereby reframing our understanding of time as a relative phenomenon deeply interconnected with the dynamic state of the universe. This groundbreaking perspective could pave the way for a unified theory of physics, merging gravity and quantum mechanics into a cohesive framework that explains not just black holes but also the entire fabric of the universe.

As exciting as these implications are, they also invite skepticism and further exploration. While the concept of white holes and the relationship between dark energy and time are largely theoretical at this stage, they invite intriguing discussions among physicists and cosmologists. Gielen’s work can serve as a launching point for additional studies aimed at verifying these ideas through observational data or advanced simulation models.

Ultimately, the University of Sheffield’s findings could lead to a reconciliation of longstanding paradoxes in physics, including the infamous information paradox associated with black holes. This enigma questions what happens to information when it falls into a black hole. If the theoretical models presented by the researchers hold up, it might be possible not only to resolve this paradox but also to provide a deeper insight into the fundamental processes driving our universe’s evolution.

Continued research and dialogue will undoubtedly enrich this area of inquiry, generating excitement about future discoveries that could redefine our very existence within the cosmos. As scientists expand their toolkit with new technologies and theoretical approaches, the mysteries of black holes, time, and dark energy promise to remain an enduring frontier in the quest for knowledge and understanding of the universe and our place within it.

In conclusion, the implications of this university study are monumental, urging both physicists and the wider scientific community to reassess their understanding of fundamental cosmic phenomena. It underscores an exhilarating frontier in scientific inquiry that not only seeks to answer pressing questions about our universe but also challenges us to rethink what we thought we knew about the nature of reality itself.

Subject of Research: Theoretical aspects of black holes and the relationship between time and dark energy.
Article Title: Black Hole Singularity Resolution in Unimodular Gravity from Unitarity.
News Publication Date: 12-Mar-2025.
Web References: Physical Review Letters
References: Not applicable.
Image Credits: Credit: University of Sheffield.
Keywords: Black holes, white holes, dark energy, time, quantum mechanics, singularity.