The Dark matter Nanosatellite Equipped with Skipper Sensors (DarkNESS) mission is a 6U CubeSat designed to search for X-ray lines from decaying dark matter using Skipper-CCDs. Thick, fully-depleted p-channel Skipper-CCDs provide low readout noise and high quantum efficiency for 1-10 keV X-rays, but their X-ray performance has not yet been demonstrated in the space environment. DarkNESS will operate in low-Earth orbit, where trapped protons induce displacement damage in the sensor that increases charge-transfer inefficiency and degrades the X-ray energy resolution. This work measures the X-ray line response of Skipper-CCDs before and after proton irradiation and quantifies the associated degradation. A sensor was exposed to 217 MeV protons at a fluence of 8.4 x 10^10 protons cm^-2, corresponding to a displacement-damage dose more than an order of magnitude above the three-year expectation for representative mid-inclination and Sun-synchronous low-Earth orbits. A 55Fe source was used to compare the energy resolution of the beam-exposed quadrant to adjacent unexposed quadrants and a non-irradiated reference sensor. These measurements provide a quantitative assessment of radiation-indu
The DarkNESS (Dark Matter Nano-satellite Equipped with Skipper Sensors) mission aims to deploy a skipper-CCD CubeSat Observatory to search for dark matter (DM) from Low Earth Orbit. This mission will employ novel skipper-CCDs to investigate O(keV) X-rays from decaying DM, as well as electron recoils from strongly-interacting sub-GeV DM. The DarkNESS mission will be the first space deployment of skipper-CCDs, and the DarkNESS team is developing a skipper-CCD instrument that is compatible with the CubeSat platform. DarkNESS has recently progressed from laboratory validation to a Critical Design Review (CDR) phase, with a launch opportunity anticipated in late 2025. The implementation of the DarkNESS skipper-CCD payload on the CubeSat platform will pave the way for future demonstrators of space-based imagers for X-ray and single-electron counting applications.
Autonomous aerial navigation in absolute darkness is crucial for post-disaster search and rescue operations, which often occur from disaster-zone power outages. Yet, due to resource constraints, tiny aerial robots, perfectly suited for these operations, are unable to navigate in the darkness to find survivors safely. In this paper, we present an autonomous aerial robot for navigation in the dark by combining an Infra-Red (IR) monocular camera with a large-aperture coded lens and structured light without external infrastructure like GPS or motion-capture. Our approach obtains depth-dependent defocus cues (each structured light point appears as a pattern that is depth dependent), which acts as a strong prior for our AsterNet deep depth estimation model. The model is trained in simulation by generating data using a simple optical model and transfers directly to the real world without any fine-tuning or retraining. AsterNet runs onboard the robot at 20 Hz on an NVIDIA Jetson Orin$^\text{TM}$ Nano. Furthermore, our network is robust to changes in the structured light pattern and relative placement of the pattern emitter and IR camera, leading to simplified and cost-effective constructio
Long-duration gamma-ray bursts (GRBs) are believed to occur in star-forming regions. The multiwavelength follow-up observations of the early afterglow of GRB 240825A provided insights into the evolution of the optical-to-X-ray spectral feature of the afterglow. We comprehensively investigate the evolution of X-ray spectral properties through time-resolved spectral analysis and calculate optical darkness ($β_\mathrm{OX}$) to reveal the physical properties of the afterglow. The X-ray-to-optical SEDs of afterglow in different time intervals are fitted to derive the extinction curves. The $β_\mathrm{OX}$ exhibits a trend of decreasing and then increasing, reaching its minimum value at $\sim1000\mathrm{\,s}$ post-trigger. However, at 11 hours post-trigger, $β_\mathrm{OX}$ does not meet the criteria for an optically dark burst. The extinction curves in different time intervals indicate that GRB 240825A occurred in a dust-obscured environment.
In experiments requiring extreme darkness, such as experiments probing the limits of human vision, assessment of the background photon flux is essential. However, direct measurement thereof with standard single photon detectors is challenged by dark counts and their fluctuations. Here we report an experiment and detailed statistical analysis of a direct measurement of darkness in a dedicated dark chamber suitable for human vision experiments, only using a standard single photon detector and a mechanical shutter. From a Bayesian analysis of $616$ h of data, we find substantial to decisive evidence for absolute darkness (depending on choice of prior distribution) based on the Savage-Dickey ratio, and a light level $<0.039$ cnt/s (posterior $0.95$-highest density interval).
Gamma-ray bursts categorically produce broadband afterglow emission, but in some cases, emission in the optical band is dimmer than expected based on the contemporaneously observed X-ray flux. This phenomenon, aptly dubbed "optical darkness", has been studied extensively in long GRBs (associated with the explosive deaths of massive stars), with possible explanations ranging from host environment extinction to high redshift to possibly unique emission mechanisms. However, investigations into optical darkness in short GRBs (associated with the mergers of compact object binaries) have thus far been limited. This work implements a procedure for determining the darkness of GRBs based on spectral indices calculated using temporally-matched Swift-XRT data and optical follow-up observations; presents a complete and up-to-date catalog of known short GRBs that exhibit optical darkness; and outlines some of the possible explanations for optically dark short GRBs. In the process of this analysis, we developed versatile and scalable data processing code that facilitates reproducibility and reuse of our pipeline. These analysis tools and resulting complete sample of dark short GRBs enable a syst
Existing nighttime unmanned aerial vehicle (UAV) trackers follow an "Enhance-then-Track" architecture - first using a light enhancer to brighten the nighttime video, then employing a daytime tracker to locate the object. This separate enhancement and tracking fails to build an end-to-end trainable vision system. To address this, we propose a novel architecture called Darkness Clue-Prompted Tracking (DCPT) that achieves robust UAV tracking at night by efficiently learning to generate darkness clue prompts. Without a separate enhancer, DCPT directly encodes anti-dark capabilities into prompts using a darkness clue prompter (DCP). Specifically, DCP iteratively learns emphasizing and undermining projections for darkness clues. It then injects these learned visual prompts into a daytime tracker with fixed parameters across transformer layers. Moreover, a gated feature aggregation mechanism enables adaptive fusion between prompts and between prompts and the base model. Extensive experiments show state-of-the-art performance for DCPT on multiple dark scenario benchmarks. The unified end-to-end learning of enhancement and tracking in DCPT enables a more trainable system. The darkness clue
Topology, which originated as a mathematical discipline, nowadays advances the understanding of many branches of science and technology from elementary particle physics and cosmology to condensed matter physics. In optics, the topology of light and darkness facilitates new degrees of freedom for sculpting optical beams beyond conventionally used amplitude, phase, and polarization. This fundamentally new, spatial dimension opens new opportunities for several optical applications, ranging from optical manipulation, trapping, data processing, optical sensing and metrology, enhanced imaging, and microscopy, to classical and quantum communications. While topological stability of mathematical knots implying robustness to perturbations suggests their potential as information carriers, the behavior of optical knots in perturbative environments such as atmospheric turbulence is largely unexplored. Here, we experimentally and theoretically investigate the effects of atmospheric turbulence of optical knot stability and demonstrate that the number of crossing (the topological invariant) is preserved in the weak-turbulence regime, but may not be conserved in the stronger turbulence conditions.
Dark matter is theorised to form massive haloes, which could be further condensed into so-called spikes when a black hole grows at the centre of such a halo. The existence of these spikes is instrumental for several dark matter detection schemes such as indirect detection and imprints on gravitational wave inspirals, but all previous work on their formation has been (semi-)analytical. We present fully numerically simulated cold dark matter spikes using the SWIFT code. Based on these results, we propose a simple empirical density profile - dependent on only a single mass-ratio parameter between the black hole and total mass - for dark matter spikes grown in Hernquist profiles. We find that the radius of the spike scales differently compared to theoretical predictions, and show a depletion of the outer halo that is significant for high mass-ratio systems. We critically assess approximations of the spike as used in the field, show that our profile significantly deviates, and contextualise the potential influence for future dark matter detections by simulating binary black hole inspirals embedded in our profile.
Mass dimension one fermionic fields are prime candidates to describe dark matter, due to their intrinsic neutral nature, as they are constructed as eigenstates of the charge conjugation operator with dual helicity. To formulate the meaning of the darkness, the fermion-photon coupling is scrutinized with a Pauli-like interaction, and the path integral is then formulated from the phase space constraint structure. Ward-Takahashi-like identities and Schwinger-Dyson equations, together with renormalizability, are employed to investigate a phenomenological mechanism to avoid external light signals. Accordingly, the non-polarized pair annihilation and Compton-like processes are shown to vanish at the limit of small scattering angles even if considering 1-loop radiative corrections, reinforcing the dark matter interpretation. However, dark matter interactions with nucleons are still possible. Motivated by recent nucleon-recoil experiments to detect dark matter, we furnish a consistent theoretical setup to describe interaction with the photon compatible with the prevalence of darkness.
This report summarises the talks and discussions that took place over the course of the MITP Youngst@rs Colours in Darkness workshop 2023. All talks can be found at https://indico.mitp.uni-mainz.de/event/377/.
We theoretically and experimentally demonstrate the focusing of macroscopic 3D darkness surrounded by all light in free space. The object staying in the darkness is similar to staying in an empty light capsule because light just bypasses it by resorting to destructive interference. Its functionality of controlling the direction of energy flux of light macroscopically is fascinating, similar in some sense to the transformation-based cloaking effect. Binary-optical system exhibiting anti-resolution (AR) is designed and fabricated, by which electromagnetic energy flux avoids and bends smoothly around a nearly perfect darkness region. AR remains an unexplored topic hitherto, in contrast to the super-resolution for realizing high spatial resolution. This novel scheme replies on smearing out the PSF and thus poses less stringent limitations upon the object's size and position since the created dark (zero-field) area reach 8 orders of magnitude larger than the square of wavelength in size. It functions very well at arbitrarily polarized beams in three dimensions, which is also frequency-scalable in the whole electromagnetic spectrum.
Let $Θ$ be the Wigner time reversal operator for spin half and let $φ$ be a Weyl spinor. Then, for a left-transforming $φ$, the construct $ζ_λΘφ^\ast$ yields a right-transforming spinor. If instead, $φ$ is a right-transforming spinor, then the construct $ζ_ρΘφ^\ast$ results in a left-transforming spinor ($ζ_{λ,ρ}$ are phase factors). This allows us to introduce two sets of four-component spinors. Setting $ζ_λ$ and $ζ_ρ$ to $\pm i$ render all eight spinors as eigenspinor of the charge conjugation operator~$\mathcal{C}$ (called ELKO). This allows us to introduce two quantum fields. A calculation of the vacuum expectation value of the time-ordered product of the fields and their adjoints reveals the mass dimension of the fields to be one. Both fields are local in the canonical sense of quantum field theory. Interestingly, one of the fields is fermionic and the other bosonic. The mass dimension of the introduced fermionic fields and the matter fields of the Standard Model carry an intrinsic mismatch. As such, they provide natural darkness for the new fields with respect to the Standard Model doublets. The statistics and locality are controlled by a set of phases. These are explicitly g
We present DARKNESS (the DARK-speckle Near-infrared Energy-resolving Superconducting Spectrophotometer), the first of several planned integral field spectrographs to use optical/near-infrared Microwave Kinetic Inductance Detectors (MKIDs) for high-contrast imaging. The photon counting and simultaneous low-resolution spectroscopy provided by MKIDs will enable real-time speckle control techniques and post-processing speckle suppression at framerates capable of resolving the atmospheric speckles that currently limit high-contrast imaging from the ground. DARKNESS is now operational behind the PALM-3000 extreme adaptive optics system and the Stellar Double Coronagraph at Palomar Observatory. Here we describe the motivation, design, and characterization of the instrument, early on-sky results, and future prospects.
Assuming the validity of the general relativistic description of gravitation on astrophysical and cosmological length scales, we analytically infer that the Friedmann-Robertson-Walker cosmology with Einsteinian cosmological constant, and a vanishing spatial curvature constant, unambiguously requires significant amount of dark matter. This requirement is consistent with other indications for dark matter. The same spacetime symmetries that underlie the freely falling frames of Einsteinian gravity also provide symmetries, which for the spin one half representation space, furnish a novel construct that carries extremely limited interactions with respect to the terrestrial detectors made of the standard model material. Both the `luminous' and `dark' matter turn out to be residents of the same representation space but they derive their respective `luminosity' and `darkness' from either belonging to the sector with (CPT)^2 = + 1, or to the sector with (CPT)^2 = - 1.
We theoretically analyze and experimentally measure the extrinsic angular momentum contribution of topologically structured darkness found within fractional vortex beams, and show that this structured darkness can be explained by evanescent waves at phase discontinuities in the generating optic. We also demonstrate the first direct measurement of the intrinsic orbital angular momentum of light with both intrinsic and extrinsic angular momentum, and explain why the total orbital angular momenta of fractional vortices do not match the winding number of their generating phases.
Small aerial robots are particularly well-suited for search and rescue in confined and hazardous environments due to their agility, low cost, and ability to traverse through cluttered spaces that are inaccessible to larger platforms. However, enabling autonomous navigation in complete darkness remains a significant challenge, because small aerial robots cannot easily accommodate perception systems that demand substantial payload, power, or computation. In this work, we present a lightweight perception approach that combines a monocular event camera, a coded aperture lens, and an infrared dot projector to enable navigation in such conditions. The projected pattern, when imaged through the coded aperture, produces depth dependent blur signatures that implicitly encode scene geometry. We train a convolutional neural network to decode these signatures into dense depth maps using only synthetic data generated from a simple planar wall setup. Despite this minimal training regime, the model generalizes zero-shot to complex real-world scenes. Our system operates in real time at 20 Hz on a NVIDIA Jetson Orin Nano, demonstrating suitability for resource-constrained platforms. We further anal
Black materials play a critical role in applications such as image registration, camera calibration, stray light suppression, and visual design. Although many such materials appear similarly dark under diffuse illumination, their reflectance behavior can differ substantially as a function of viewing and lighting geometry. Ultra-black materials achieve exceptional light attenuation but are often constrained by cost and mechanical fragility, motivating the evaluation of more robust and accessible alternatives. In this study, we employ a gonimetric measurement system to capture the isotropic bidirectional reflectance distribution function of a range of black materials, including the ultra-black reference Vantablack, commercially available alternatives such as Musou Black and black velvet, and standard matte black coatings. We analyze their reflectance characteristics in terms of diffuse and specular scattering, as well as total integrated scatter, to quantify angular-dependent reflection. In addition, we compare their perceptual appearance using physically based rendering driven by the measured BRDFs and a psychophysical evaluation of perceived darkness. Together, these analyses provi
In robot vision, thermal cameras hold great potential for recognizing humans even in complete darkness. However, their application to multi-person tracking (MPT) has been limited due to data scarcity and the inherent difficulty of distinguishing individuals. In this study, we propose a cooperative MPT system that utilizes co-located RGB and thermal cameras, where pseudo-annotations (bounding boxes and person IDs) are used to train both RGB and thermal trackers. Evaluation experiments demonstrate that the thermal tracker performs robustly in both bright and dark environments. Moreover, the results suggest that a tracker-switching strategy -- guided by a binary brightness classifier -- is more effective for information integration than a tracker-fusion approach. As an application example, we present an image change pattern recognition (ICPR) method, the ``human-as-landmark,'' which combines two key properties: the thermal recognizability of humans in dark environments and the rich landmark characteristics -- appearance, geometry, and semantics -- of static objects (occluders). Whereas conventional SLAM focuses on mapping static landmarks in well-lit environments, the present study ta
The Cosmic Dark Ages mark a pivotal era of the universe's evolution, transitioning from a neutral, opaque medium to the emergence of the first stars and galaxies that initiated cosmic reionization. This study examines the thermodynamics of the intergalactic medium (IGM), molecular hydrogen cooling, and gravitational collapse that led to structure formation. Key emission lines, such as Lyman-alpha (Ly$α$) and [C II] 158 $μm$, are analyzed as tracers of star formation, metallicity, and IGM conditions. Simulations highlight Ly$α$ scattering profiles and [C II] emission as critical diagnostics of early galaxy evolution. The findings provide a theoretical framework to interpret high-redshift observations, advancing our understanding of the universe's transition from darkness to illumination.