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Verifying the fully kinematic nature of the cosmic microwave background (CMB) dipole is of fundamental importance in cosmology. In the standard cosmological model with the Friedman-Lemaitre-Robertson-Walker (FLRW) metric from the inflationary expansion the CMB dipole should be entirely kinematic. Any non-kinematic CMB dipole component would thus reflect the preinflationary structure of spacetime probing the extent of the FLRW applicability. Cosmic backgrounds from galaxies after the matter-radiation decoupling, should have kinematic dipole component identical in velocity with the CMB kinematic dipole. Comparing the two can lead to isolating the CMB non-kinematic dipole. It was recently proposed that such measurement can be done using the near-IR cosmic infrared background (CIB) measured with the currently operating Euclid telescope, and later with Roman. The proposed method reconstructs the resolved CIB, the Integrated Galaxy Light (IGL), from Euclid's Wide Survey and probes its dipole, with a kinematic component amplified over that of the CMB by the Compton-Getting effect. The amplification coupled with the extensive galaxy samples forming the IGL would determine the CIB dipole with an overwhelming signal/noise, isolating its direction to sub-degree accuracy. We develop details of the method for Euclid's Wide Survey in 4 bands spanning 0.6 to 2 mic. We isolate the systematic and other uncertainties and present methodologies to minimize them, after confining the sample to the magnitude range with negligible IGL/CIB dipole from galaxy clustering. These include the required star-galaxy separation, accounting for the extinction correction dipole using the method newly developed here achieving total separation, accounting for the Earth's orbital motion and other systematic effects. (Abridged)
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A large-scale and diverse benchmark, BIG-bench, was introduced to rigorously evaluate the capabilities and limitations of large language models across 204 tasks. The evaluation revealed that even state-of-the-art models currently achieve aggregate scores below 20 (on a 0-100 normalized scale), indicating significantly lower performance compared to human experts.
Utilizing the Atacama Cosmology Telescope's Data Release 6, researchers rigorously tested the standard "Lambda Cold Dark Matter" (ΛCDM) cosmological model and constrained numerous extensions to it, finding continued consistency with ΛCDM and setting the tightest limits to date on many fundamental physics parameters, while observing no statistical preference for models designed to alleviate cosmological tensions like the Hubble or S₈ discrepancies.
Despite the first detection of fast radio bursts (FRBs) being as recent as 2007, they have already been proven to be a fantastic tool as a unique cosmological probe. In this chapter, after a brief introduction to FRBs and how they are currently detected, we describe various cosmological questions and how FRB research has both aided previous studies and can continue to do so. Topics include placing constraints on cosmological parameters to understanding the distribution of baryons throughout the Universe. We conclude with some notes on the challenges to be overcome and how to best enable ongoing and future FRB-based studies of cosmology.
We investigate Krylov complexity in open quantum systems using Lindblad master equations for bosonic bath models, with particular emphasis on the Caldeira--Leggett model. Krylov complexity is computed from the moments of the two-point function within the standard master equation framework. For the damped harmonic oscillator, the results reveal clear dissipative features in Krylov complexity. In the Caldeira--Leggett model, in the high-temperature limit, we find that Krylov complexity saturates in the full system and reproduces the expected dissipative behavior when the decoherence term is suppressed in the master equation. Conversely, when the dissipative term is suppressed, the contribution from decoherence exhibits the familiar oscillatory dynamics of the coherent system, along with additional novel features. However, Krylov complexity appears insensitive to the onset of decoherence, as no clear distinctive signature is observed. We attribute this to the fact that Krylov complexity is defined in the Krylov basis, which does not coincide with the conventional basis typically used to study decoherence.
Researchers demonstrated that Large Language Models can classify astronomical transient images with high accuracy (averaging 93% across diverse datasets) while simultaneously generating human-readable explanations and self-assessing classification uncertainty. This approach overcomes the "black box" limitation of traditional convolutional neural networks in automated astronomical data analysis.
We present Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) maps of the Cosmic Microwave Background temperature and polarization anisotropy at arcminute resolution over three frequency bands centered on 98, 150 and 220 GHz. The maps are based on data collected with the AdvancedACT camera over the period 2017--2022 and cover 19,000 square degrees with a median combined depth of 10 uK arcmin. We describe the instrument, mapmaking and map properties and illustrate them with a number of figures and tables. The ACT DR6 maps and derived products are available on LAMBDA at this https URL We also provide an interactive web atlas at this https URL and HiPS data sets in Aladin (e.g. this https URL).
We report the discovery of 164 compact (radius < 1 arcmin) radio rings using MeerKAT 1.3 GHz data from the SARAO MeerKAT Galactic Plane Survey (l=2-60deg, 252-358deg, |b|<1.5deg) and the Galactic Centre mosaic, from a search aimed at identifying previously uncatalogued radio sources. Within this sample, approximately 19 per cent of the rings contain a central point radio source. A multiwavelength analysis reveals a striking diversity: about 40 per cent of the rings enclose an isolated infrared point source, 50 per cent exhibit an extended counterpart in the mid- or far-infrared, and several are only detected in the radio band. We found that 17 per cent of the rings in the sample are positionally coincident (within 5 arcsec) with known entries in SIMBAD, including unclassified infrared sources, spiral galaxies, young stellar objects and long-period variable candidates. Based on these matches and exploiting ancillary multiwavelength data and catalogues, we explore several formation scenarios for the rings, such as HII regions, planetary nebulae, mass-loss relics from evolved massive stars, supernova remnants, nova shells, galaxies, galaxy cluster lenses and odd radio circles. Tentative classifications are proposed for nearly 60 per cent of the sample. These results highlight the potential of MeerKAT to uncover previously undetected compact radio structures and, particularly, recover missing Galactic radio-emitting objects.
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We describe updated scientific goals for the wide-field, millimeter-wave survey that will be produced by the Simons Observatory (SO). Significant upgrades to the 6-meter SO Large Aperture Telescope (LAT) are expected to be complete by 2028, and will include a doubled mapping speed with 30,000 new detectors and an automated data reduction pipeline. In addition, a new photovoltaic array will supply most of the observatory's power. The LAT survey will cover about 60% of the sky at a regular observing cadence, with five times the angular resolution and ten times the map depth of Planck. The science goals are to: (1) determine the physical conditions in the early universe and constrain the existence of new light particles; (2) measure the integrated distribution of mass, electron pressure, and electron momentum in the late-time universe, and, in combination with optical surveys, determine the neutrino mass and the effects of dark energy via tomographic measurements of the growth of structure at z &lt; 3; (3) measure the distribution of electron density and pressure around galaxy groups and clusters, and calibrate the effects of energy input from galaxy formation on the surrounding environment; (4) produce a sample of more than 30,000 galaxy clusters, and more than 100,000 extragalactic millimeter sources, including regularly sampled AGN light-curves, to study these sources and their emission physics; (5) measure the polarized emission from magnetically aligned dust grains in our Galaxy, to study the properties of dust and the role of magnetic fields in star formation; (6) constrain asteroid regoliths, search for Trans-Neptunian Objects, and either detect or eliminate large portions of the phase space in the search for Planet 9; and (7) provide a powerful new window into the transient universe on time scales of minutes to years, concurrent with observations from Rubin of overlapping sky.
Gliomas are the most common type of primary brain tumors. Although gliomas are relatively rare, they are among the deadliest types of cancer, with a survival rate of less than 2 years after diagnosis. Gliomas are challenging to diagnose, hard to treat and inherently resistant to conventional therapy. Years of extensive research to improve diagnosis and treatment of gliomas have decreased mortality rates across the Global North, while chances of survival among individuals in low- and middle-income countries (LMICs) remain unchanged and are significantly worse in Sub-Saharan Africa (SSA) populations. Long-term survival with glioma is associated with the identification of appropriate pathological features on brain MRI and confirmation by histopathology. Since 2012, the Brain Tumor Segmentation (BraTS) Challenge have evaluated state-of-the-art machine learning methods to detect, characterize, and classify gliomas. However, it is unclear if the state-of-the-art methods can be widely implemented in SSA given the extensive use of lower-quality MRI technology, which produces poor image contrast and resolution and more importantly, the propensity for late presentation of disease at advanced stages as well as the unique characteristics of gliomas in SSA (i.e., suspected higher rates of gliomatosis cerebri). Thus, the BraTS-Africa Challenge provides a unique opportunity to include brain MRI glioma cases from SSA in global efforts through the BraTS Challenge to develop and evaluate computer-aided-diagnostic (CAD) methods for the detection and characterization of glioma in resource-limited settings, where the potential for CAD tools to transform healthcare are more likely.
CNRS logoCNRSCalifornia Institute of Technology logoCalifornia Institute of TechnologyUniversity of OsloUniversity of Waterloo logoUniversity of WaterlooUniversity College London logoUniversity College LondonUniversity of Bristol logoUniversity of BristolUniversity of EdinburghNASA Goddard Space Flight Center logoNASA Goddard Space Flight CenterLancaster UniversityUniversidad Autónoma de MadridUniversité Paris-Saclay logoUniversité Paris-SaclayHelsinki Institute of PhysicsUniversity of HelsinkiPerimeter Institute for Theoretical Physics logoPerimeter Institute for Theoretical PhysicsUniversité de GenèveLeiden University logoLeiden UniversityCEA logoCEAUniversity of PortsmouthUniversitat de BarcelonaAlma Mater Studiorum - Università di BolognaLudwig-Maximilians-Universität MünchenUniversidad Complutense de MadridKTH Royal Institute of Technology logoKTH Royal Institute of TechnologyUniversity of SussexObservatoire de ParisTechnical University of DenmarkUniversità di TriesteDurham University logoDurham UniversityUniversity of Groningen logoUniversity of GroningenInstituto de Astrofísica e Ciências do EspaçoJet Propulsion LaboratorySwinburne University of TechnologyUniversity of Cape TownÉcole Polytechnique Fédérale de LausanneRuhr-Universität BochumSISSACNESINFN, Sezione di TorinoUniversidad Andrés BelloUniversity of Hawai’iNiels Bohr Institute, University of CopenhagenLaboratoire d’Astrophysique de MarseilleInstituto de Astrofísica de Andalucía, IAA-CSICINAF – Osservatorio Astronomico di RomaInstituto de Astrofísica de Canarias (IAC)Institut d'Astrophysique de ParisUniversidad de SalamancaInstitut de Física d’Altes Energies (IFAE)Institut d’Estudis Espacials de Catalunya (IEEC)INFN - Sezione di PadovaLeibniz-Institut für Astrophysik Potsdam (AIP)INAF-IASF MilanoInstitute of Space ScienceInstitut d’Astrophysique SpatialeEuropean Space Agency (ESA)INFN-Sezione di BolognaINFN Sezione di RomaINFN NapoliUniversidad Politécnica de CartagenaInstitut de Ciències de l’Espai (ICE, CSIC)Argelander-Institut für Astronomie, Universität BonnInstituto Nacional de Técnica Aeroespacial (INTA)AIMASI - Agenzia Spaziale ItalianaInstitut de Ciències del Cosmos (ICCUB)NOVA UniversityESACDanish Space Research InstituteHEPHYSpace Science Data Center (SSDC)INFN-Sezione di Roma TreAfrican Institute for Mathematical Sciences - South AfricaInstituto de Física de Cantabria (IFCA, CSIC-UC)Universit degli Studi di FerraraUniversit de ParisUniversit de ToulouseUniversit Claude Bernard Lyon 1INAF Osservatorio Astronomico di CapodimonteMax Planck Institut fr AstronomieAix-Marseille Universit",Max Planck-Institute for Extraterrestrial PhysicsUniversit de LyonSapienza Universit di RomaUniversit di PadovaUniversit degli Studi di MilanoINAF Osservatorio Astronomico di PadovaUniversit degli Studi di TorinoUniversit degli Studi di Napoli Federico IIINAF Osservatorio di Astrofisica e Scienza dello Spazio di BolognaIFPU Institute for fundamental physics of the UniverseINFN Sezione di TriesteINAF ` Osservatorio Astronomico di TriesteINAF Osservatorio Astronomico di BreraUniversity of Milano Bicocca
The Euclid Collaboration's CLOE.6 paper quantifies the impact of various systematic uncertainties on cosmological parameter inference for the upcoming Euclid mission, utilizing the CLOE likelihood code. The study demonstrates that intrinsic alignments and spectroscopic purity are critical systematics, with potential biases up to 6.54 on cosmological parameters, providing essential guidance for optimizing analysis pipelines.
Radio synchrotron emission originates from both massive star formation and black hole accretion, two processes that drive galaxy evolution. Efficient classification of sources dominated by either process is therefore essential for fully exploiting deep, wide-field extragalactic radio continuum surveys. In this study, we implement, optimize, and compare five widely used supervised machine-learning (ML) algorithms to classify radio sources detected in the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE)-COSMOS survey as star-forming galaxies (SFGs) and active galactic nuclei (AGN). Training and test sets are constructed from conventionally classified MIGHTEE-COSMOS sources, and 18 physical parameters of the MIGHTEE-detected sources are evaluated as input features. As anticipated, our feature analyses rank the five parameters used in conventional classification as the most effective: the infrared-radio correlation parameter (qIRq_\mathrm{IR}), the optical compactness morphology parameter (class_\_star), stellar mass, and two combined mid-infrared colors. By optimizing the ML models with these selected features and testing classifiers across various feature combinations, we find that model performance generally improves as additional features are incorporated. Overall, all five algorithms yield an F1F1-score (the harmonic mean of precision and recall) >90%>90\% even when trained on only 20%20\% of the dataset. Among them, the distance-based kk-nearest neighbors classifier demonstrates the highest accuracy and stability, establishing it as a robust and effective method for classifying SFGs and AGN in upcoming large radio continuum surveys.
We apply the exponential operator method to derive the propagator for a fermion immersed within a rigidly rotating environment with cylindrical geometry. Given that the rotation axis provides a preferred direction, Lorentz symmetry is lost and the general solution is not translationally invariant in the radial coordinate. However, under the approximation that the fermion is completely dragged by the vortical motion, valid for large angular velocities, translation invariance is recovered. The propagator can then be written in momentum space. The result is suited to be used applying ordinary Feynman rules for perturbative calculations in momentum space.
Being able to harness the power of large datasets for developing cooperative multi-agent controllers promises to unlock enormous value for real-world applications. Many important industrial systems are multi-agent in nature and are difficult to model using bespoke simulators. However, in industry, distributed processes can often be recorded during operation, and large quantities of demonstrative data stored. Offline multi-agent reinforcement learning (MARL) provides a promising paradigm for building effective decentralised controllers from such datasets. However, offline MARL is still in its infancy and therefore lacks standardised benchmark datasets and baselines typically found in more mature subfields of reinforcement learning (RL). These deficiencies make it difficult for the community to sensibly measure progress. In this work, we aim to fill this gap by releasing off-the-grid MARL (OG-MARL): a growing repository of high-quality datasets with baselines for cooperative offline MARL research. Our datasets provide settings that are characteristic of real-world systems, including complex environment dynamics, heterogeneous agents, non-stationarity, many agents, partial observability, suboptimality, sparse rewards and demonstrated coordination. For each setting, we provide a range of different dataset types (e.g. Good, Medium, Poor, and Replay) and profile the composition of experiences for each dataset. We hope that OG-MARL will serve the community as a reliable source of datasets and help drive progress, while also providing an accessible entry point for researchers new to the field.
14 Oct 2008
We present rotation curves of 19 galaxies from THINGS, The HI Nearby Galaxy Survey. The high spatial and velocity resolution of THINGS make these the highest quality HI rotation curves available to date for a large sample of nearby galaxies, spanning a wide range of HI masses and luminosities. The high quality of the data allows us to derive the geometrical and dynamical parameters using HI data alone. We do not find any declining rotation curves unambiguously associated with a cut-off in the mass distribution out to the last measured point. The rotation curves are combined with 3.6 um data from SINGS (Spitzer Infrared Nearby Galaxies Survey) to construct mass models. Our best-fit, dynamical disk masses, derived from the rotation curves, are in good agreement with photometric disk masses derived from the 3.6 um images in combination with stellar population synthesis arguments and two different assumptions for the stellar Initial Mass Function (IMF). We test the Cold Dark Matter-motivated cusp model, and the observationally motivated central density core model and find that (independent of IMF) for massive, disk-dominated galaxies, all halo models fit apparently equally well; for low-mass galaxies, however, a core-dominated halo is clearly preferred over a cuspy halo. The empirically derived densities of the dark matter halos of the late-type galaxies in our sample are half of what is predicted by CDM simulations, again independent of the assumed IMF.
Knowledge Representation and Reasoning is a central, longstanding, and active area of Artificial Intelligence. Over the years it has evolved significantly; more recently it has been challenged and complemented by research in areas such as machine learning and reasoning under uncertainty. In July 2022 a Dagstuhl Perspectives workshop was held on Knowledge Representation and Reasoning. The goal of the workshop was to describe the state of the art in the field, including its relation with other areas, its shortcomings and strengths, together with recommendations for future progress. We developed this manifesto based on the presentations, panels, working groups, and discussions that took place at the Dagstuhl Workshop. It is a declaration of our views on Knowledge Representation: its origins, goals, milestones, and current foci; its relation to other disciplines, especially to Artificial Intelligence; and on its challenges, along with key priorities for the next decade.
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The intrinsic width and scattering distributions of fast radio bursts (FRBs) inform on their emission mechanism and local environment, and act as a source of detection bias and, hence, an obfuscating factor when performing FRB population and cosmological studies. Here, we utilise a sample of 29 FRBs with measured high-time-resolution properties and known redshift, which were detected using the Australian Square Kilometre Array Pathfinder (ASKAP) by the Commensal Real-time ASKAP Fast Transients Survey (CRAFT), to model these distributions. Using this sample, we estimate the completeness bias of intrinsic width and scattering measurements, and fit the underlying, de-biased distributions in the host rest-frame. We find no evidence for a down-turn towards high values of the intrinsic distributions of either parameter in the 0.01-40 ms range probed by the data. Rather, the intrinsic scattering distribution at 1 GHz is consistent with a log-uniform distribution above 0.04 ms, while the intrinsic width distribution rises as a Gaussian in log-space in the 0.03-0.3 ms range, and is then log-uniform above that. This is inconsistent with previous works, which assumed that these parameters have lognormal distributions. This confirms that FRB observations are currently strongly width- and scattering-limited, and we encourage FRB searches to be extended to higher values of time-width. It also implies a bias in FRB host galaxy studies, although the form of that bias is uncertain. Finally, we find that our updated width and scattering model - when implemented in the zDM code - produces 10% more FRBs at redshift z=1z=1 than at z=0z=0 when compared to alternative width/scattering models, highlighting that these factors are important to understand when performing FRB population modelling.
We develop computational tools necessary to extend the application of Krylov complexity beyond the simple Hamiltonian systems considered thus far in the literature. As a first step toward this broader goal, we show how the Lanczos algorithm that iteratively generates the Krylov basis can be augmented to treat coherent states associated with the Jacobi group, the semi-direct product of the 3-dimensional real Heisenberg-Weyl group H1H_{1}, and the symplectic group, Sp(2,R)SU(1,1)Sp(2,\mathbb{R})\simeq SU(1,1). Such coherent states are physically realized as squeezed states in, for example, quantum optics. With the Krylov basis for both the SU(1,1)SU(1,1) and Heisenberg-Weyl groups being well understood, their semi-direct product is also partially analytically tractable. We exploit this to benchmark a scheme to numerically compute the Lanczos coefficients which, in principle, generalizes to the more general Jacobi group $H_{n}\rtimes Sp(2n,\mathbb{R})$.
A key challenge in offline multi-agent reinforcement learning (MARL) is achieving effective many-agent multi-step coordination in complex environments. In this work, we propose Oryx, a novel algorithm for offline cooperative MARL to directly address this challenge. Oryx adapts the recently proposed retention-based architecture Sable and combines it with a sequential form of implicit constraint Q-learning (ICQ), to develop a novel offline autoregressive policy update scheme. This allows Oryx to solve complex coordination challenges while maintaining temporal coherence over long trajectories. We evaluate Oryx across a diverse set of benchmarks from prior works -- SMAC, RWARE, and Multi-Agent MuJoCo -- covering tasks of both discrete and continuous control, varying in scale and difficulty. Oryx achieves state-of-the-art performance on more than 80% of the 65 tested datasets, outperforming prior offline MARL methods and demonstrating robust generalisation across domains with many agents and long horizons. Finally, we introduce new datasets to push the limits of many-agent coordination in offline MARL, and demonstrate Oryx's superior ability to scale effectively in such settings.
Routing Problems are central to many real-world applications, yet remain challenging due to their (NP-)hard nature. Amongst existing approaches, heuristics often offer the best trade-off between quality and scalability, making them suitable for industrial use. While Reinforcement Learning (RL) offers a flexible framework for designing heuristics, its adoption over handcrafted heuristics remains incomplete. Existing learned methods still lack the ability to adapt to specific instances and fully leverage the available computational budget. Current best methods either rely on a collection of pre-trained policies, or on RL fine-tuning; hence failing to fully utilize newly available information within the constraints of the budget. In response, we present MEMENTO, an approach that leverages memory to improve the search of neural solvers at inference. MEMENTO leverages online data collected across repeated attempts to dynamically adjust the action distribution based on the outcome of previous decisions. We validate its effectiveness on the Traveling Salesman and Capacitated Vehicle Routing problems, demonstrating its superiority over tree-search and policy-gradient fine-tuning; and showing that it can be zero-shot combined with diversity-based solvers. We successfully train all RL auto-regressive solvers on large instances, and verify MEMENTO's scalability and data-efficiency: pushing the state-of-the-art on 11 out of 12 evaluated tasks.
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