Future Observations Research Articles

Confirmation Bias in Sport Science: Understanding and Mitigating Its Impact.

Confirmation bias, a cognitive phenomenon deeply ingrained in human thinking, shapes our perception of reality. It leads individuals to favor information that aligns with their preexisting beliefs while dismissing or undervaluing the contrary evidence. In sport science, where precision and evidence-based practices are critical aspects to optimize performance, confirmation bias can decisively impact decision-making processes. In this context, practitioners rely on both objective and subjective data to be interpreted to enhance athletic performance. However, confirmation bias introduces a subtle yet powerful distortion, which is difficult to control and quantify. We usually believe that our observations can justify expectations or predictions about future observations, as well as broader generalizations beyond what we have directly observed-inductive inferences. Researchers and practitioners may therefore unknowingly seek out evidence that confirms their beliefs, inadvertently overlooking alternative viewpoints and interpretations. This paper explores the concept of confirmation bias in sport science, providing practical examples in the contexts of testing, training, and monitoring. By understanding how confirmation bias operates (ie,heuristic of decision making), we may develop strategies to mitigate its effects and promote more accurate and effective decision making in sport science (eg,performance).

Quantum control of ion-atom collisions beyond the ultracold regime.

Tunable scattering resonances are crucial for controlling atomic and molecular systems. However, their use has so far been limited to ultracold temperatures. These conditions remain hard to achieve for most hybrid trapped ion-atom systems-a prospective platform for quantum technologies and fundamental research. Here, we measure inelastic collision probabilities for Sr+ + Rb and use them to calibrate a comprehensive theoretical model of ion-atom collisions. Our theoretical results, compared with experimental observations, confirm that quantum interference effects persist to the multiple-partial-wave regime, leading to the pronounced state and mass dependence of the collision rates. Using our model, we go beyond interference and identify a rich spectrum of Feshbach resonances at moderate magnetic fields with the Rb atom in its lower (f = 1) hyperfine state, which persist at temperatures as high as 1 millikelvin. Future observation of these predicted resonances should allow precise control of the short-range dynamics in Sr+ + Rb collisions under unprecedentedly warm conditions.

Tidal Reconstruction of Neutron Star Mergers from Their Late Inspiral

Abstract We investigate the measurement correlation between the effective spin and the effective tidal deformability in gravitational-wave signals from binary neutron star mergers. To efficiently measure the effective tidal deformability parameter, we exploit the fact that the tidal effects in a binary system are prominent when the components are closer, during the late inspiral. Thus, we indicate a computationally efficient strategy of extracting the tidal information compressed within the seconds before the merger. We report our observations for GW170817 and explore the suitability of our approach for the upcoming observation scenarios of the current and future ground-based observatories. Fast and accurate measurements of the tidal deformability parameters can be used to inform astronomers when prioritizing the electromagnetic follow-up efforts for such sources.

Molecular inventory of the environment of a young eruptive star. Case study of the classical FU Orionis star V1057 Cyg

II ) sources, in contrast to wide-band coverages at optical and near-infrared wavelengths We carried out the first dedicated wide-band millimeter line survey toward the low-mass young eruptive star and classical FUor V1057 Cyg, which has the highest observed peak accretion rate among FUors. This source is known to have a molecular outflow, and it is associated with dense material. This makes it a good candidate for a search for molecular species. We performed a wide-band spectral line survey of V1057 Cyg with the IRAM 30 m telescope from ∼72 to ∼263,GHz (with a spatial resolution between ∼36arcsec and ∼10arcsec), complemented by on-the-fly maps of selected molecules. We also recorded additional spectra around 219, 227, 291, and 344,GHz (with a spatial resolution between ∼30arcsec and ∼19arcsec) with the APEX 12 m telescope. We conducted simple radiative transfer and population diagram analyses to derive the column densities and excitation temperatures. We constructed integrated-intensity maps of the emission from several molecular species, including those that reveal outflows. These maps and a ^12CO (3--2) position-velocity diagram provide insight into the past outburst activity of the source. We identified mainly simple C-, N-, O-, and S-bearing molecules, deuterated species, molecular ions, and complex organic molecules. Several molecular species (HCN, HC_3N, and HNC) trace large-scale (∼2arcmin) structures in the environment of V1057 Cyg with indications of small-scale fragmentation that remains unresolved by the single-dish data. The position-velocity diagram of ^12CO shows concentrated knots, which may indicate past episodic outburst activity. We calculated the dynamical timescale of the outflow and found it to be on the order of a few ten thousand years (between 15,000 and 22,000,years), similar to other eruptive stars. This suggests that the outflow cannot result from the ongoing outburst alone, since the source has been in the current outburst for less than a century. The population diagrams for species such as CH_3OH, H_2CO, and HC_3N indicate rotational temperatures that range from 8,K to 15,K and column densities that range from 1.4times10^12,cm^-2 to 2.8times10^13,cm^-2. 0/I ) FUors, e.g., V883 Ori. The results of our line survey show that V1057 Cyg is a good candidate for future interferometric observations aimed at resolving emission extents to constrain molecular freeze-out and to search for emission lines of water and additional complex organic molecules. Our observations highlight the potential of millimeter line surveys to characterize the chemistry of eruptive stars and their environments, including more evolved sources, and to complement optical and near-infrared studies in this way to improve current statistics of the molecular inventories of these objects.

Stellar X-Ray Variability and Planetary Evolution in the DS Tucanae System

Abstract We present an analysis of four Chandra observations of the 45 Myr old DS Tuc binary system. We observed X-ray variability of both stars on timescales from hours to months, including two strong X-ray flares from star A. The implied flaring rates are in agreement with past observations made with XMM-Newton, though these rates remain imprecise due to the relatively short total observation time. We find a clear, monotonic decline in the quiescent level of the star by a factor of 1.8 across 8 months, suggesting stellar variability that might be due to an activity cycle. If proven through future observations, DS Tuc A would be the youngest star for which a coronal activity cycle has been confirmed. The variation in our flux measurements across the four visits is also consistent with the scatter in empirical stellar X-ray relationships with Rossby number. In simulations of the possible evolution of the currently super-Neptune-sized planet DS Tuc A b, we find a range of scenarios for the planet once it reaches a typical field age of 5 Gyr, from Neptune size down to a completely stripped super-Earth. Improved constraints on the planet's mass in the future would significantly narrow these possibilities. We advocate for further Chandra observations to better constrain the variability of this important system.

Revisiting Near-infrared Features of Kilonovae: The Importance of Gadolinium

Abstract The observation of the kilonova AT2017gfo and investigations of its light curves and spectra confirmed that neutron star mergers are sites of r-process nucleosynthesis. However, the identification of elements responsible for the spectral features is still challenging, particularly at the near-infrared wavelengths. In this study, we systematically searched for all possible near-infrared transitions of heavy elements using experimentally calibrated energy levels. Our analysis reveals that most candidate elements with strong absorption lines are lanthanides (Z = 57–71) and actinides (Z = 89–103). This is due to their complex structures leading to many low-lying energy levels, which results in strong transitions in the near-infrared range. N. Domoto et al. (2022) have shown that La iii and Ce iii can explain the absorption features at λ ∼ 12000–15000 Å. While our results confirm that these two elements show strong infrared features, we additionally identify Gd iii as the next most promising species. Due to its unique atomic structure involving the half-filled 4f and the outer 5d orbitals, Gd iii has one of the lowest-lying energy levels, between which relatively strong transitions occur. We also find absorption lines caused by Gd iii in the near-infrared spectrum of a chemically peculiar star HR 465, which supports their emergence in kilonova spectra. By performing radiative transfer simulations, we confirm that Gd iii lines affect the feature at ∼12000 Å previously attributed to La iii. Future space-based time-series observations of kilonova spectra will allow the identification of Gd iii lines.

Reflection-driven turbulence in the super-Alfvénic solar wind

In magnetized, stratified environments such as the Sun's corona and solar wind, Alfvénic fluctuations ‘reflect’ from background gradients, enabling nonlinear interactions that allow their energy to dissipate into heat. This process, termed ‘reflection-driven turbulence’, likely plays a key role in coronal heating and solar-wind acceleration, explaining a range of detailed observational correlations and constraints. Building on previous works focused on the inner heliosphere, here we study the basic physics of reflection-driven turbulence using reduced magnetohydrodynamics in an expanding box – the simplest model that can capture local turbulent plasma dynamics in the super-Alfvénic solar wind. Although idealized, our high-resolution simulations and simple theory reveal a rich phenomenology that is consistent with a diverse range of observations. Outwards-propagating fluctuations, which initially have high imbalance (high cross-helicity), decay nonlinearly to heat the plasma, becoming more balanced and magnetically dominated. Despite the high imbalance, the turbulence is strong because Elsässer collisions are suppressed by reflection, leading to ‘anomalous coherence’ between the two Elsässer fields. This coherence, together with linear effects, causes the growth of ‘anastrophy’ (squared magnetic potential) as the turbulence decays, forcing the energy to rush to larger scales and forming a ‘ $1/f$ -range’ energy spectrum in the process. Eventually, expansion overcomes the nonlinear and Alfvénic physics, forming isolated, magnetically dominated ‘Alfvén vortices’ with minimal nonlinear dissipation. These results can plausibly explain the observed radial and wind-speed dependence of turbulence imbalance (cross-helicity), residual energy, fluctuation amplitudes, plasma heating and fluctuation spectra, as well as making a variety of testable predictions for future observations.

A Dichotomy in the 1–24 GHz Parsec-scale Radio Spectra of Radio-quiet Quasars

Abstract We present the parsec-scale radio spectra of a representative sample of 13 Palomar–Green radio-quiet quasars, based on our new Very Long Baseline Array (VLBA) observations at 8.4 and 23.6 GHz and our earlier VLBA studies at 1.5 and 5.0 GHz. The radio core emission generally exhibits a flat spectrum at 1.5–5.0 GHz, which indicates a compact optically thick synchrotron source on a scale smaller than the broad-line region (BLR) radius R BLR ∼ 0.01–0.1 pc. The 8.4–23.6 GHz spectral slope remains flat in four objects indicating the inner radius of the radio source R in < 0.1R BLR, and becomes steep in four other objects indicating R in ∼ 0.5 R BLR. The flat 8.4–23.6 GHz slope sources may be associated with a continuous ejection starting at the accretion disk corona. The steep 8.4–23.6 GHz slope sources may be produced by an interaction of an active-galactic-nucleus-driven wind with the BLR gas or a low-power jet extending to the BLR scale. Seven of these eight objects, which have a flat or steep 8.4–23.6 GHz slope, reside at the Eddington ratios L/L Edd < 0.3, and four of the remaining five objects, where the 8.4–23.6 GHz fluxes are too faint to significantly constrain the slope, reside at L/L Edd > 0.3. The 8.4–23.6 GHz radio emission in the high-L/L Edd objects may be weak due to more extended emission from a radiation-pressure-driven wind. Future submillimeter observations can further constrain the inward radial extent of the radio emission down to the coronal scale.

The Magnetically Induced Radial Velocity Variation of Gliese 341 and an Upper Limit to the Mass of Its Transiting Earth-sized Planet

Abstract The Transiting Exoplanet Survey Satellite (TESS) mission identified a potential 0.88R ⊕ planet with a period of 7.577 days, orbiting the nearby M1V star GJ 341 (TOI 741.01). This system has already been observed by the James Webb Space Telescope (JWST) to search for presence of an atmosphere on this planet. Here, we present an in-depth analysis of the GJ 341 system using all available public data. We provide improved parameters for the host star, an updated value of the planet radius, and support the planetary nature of the object (now GJ 341 b). We use 57 HARPS radial velocities to model the magnetic cycle and activity of the host star, and constrain the mass of GJ 341 b to upper limits of 4.0 M ⊕ (3σ) and 2.9 M ⊕ (1σ). We also rule out the presence of additional companions with M sin i > 15.1 M ⊕, and P < 1750 days, and the presence of contaminating background objects during the TESS and JWST observations. These results provide key information to aid the interpretation of the recent JWST atmospheric observations and other future observations of this planet.

Optimal life-cycle adaptation of coastal infrastructure under climate change

Climate change-related risk mitigation is typically addressed using cost-benefit analysis that evaluates mitigation strategies against a wide range of simulated scenarios and identifies a static policy to be implemented, without considering future observations. Due to the substantial uncertainties inherent in climate projections, this identified policy will likely be sub-optimal with respect to the actual climate trajectory that evolves in time. In this work, we thus formulate climate risk management as a dynamic decision-making problem based on Markov Decision Processes (MDPs) and Partially Observable MDPs (POMDPs), taking real-time data into account for evaluating the evolving conditions and related model uncertainties, in order to select the best possible life-cycle actions in time, with global optimality guarantees for the formulated optimization problem. The framework is developed for coastal adaptation applications, considering a wide variety of possible action types, including various forms of nature-based infrastructure. Related environmental impacts of carbon emissions and uptake are also incorporated, and social cost of carbon implications are discussed, together with several future directions and supported features.

Feedback-induced nonlinear spin dynamics in an inhomogeneous magnetic field

Nonlinear spin dynamics is essential for predicting complex behaviors of spin systems and has a wide range of applications in physics. Although spin systems have been extensively studied, many intricate behaviors such as self-organizing or chaotic oscillations still need to be better understood with a thorough analysis of nonlinear dynamics. Here we investigate the coupled dynamics of a collection of spins with multiple Larmor frequencies for modeling an inhomogeneous magnetic field and reveal that the nonlinearity induced by a feedback scheme leads to much richer stable dynamic phases, including quasi-periodic orbits and chaos besides the usual limit cycles. We further discuss the robustness of these dynamical phases against experimental noises and the feasibility of realization in various spin systems. Our findings contribute to future observation of nonlinear dynamical phases and prospective applications in spin masers, time crystals and quasi-crystals, and precision measurement.

Estimation of Over-parameterized Models from an Auto-Modeling Perspective

From a model-building perspective, we propose a paradigm shift for fitting over-parameterized models. Philosophically, the mindset is to fit models to future observations rather than to the observed sample. Technically, given an imputation method to generate future observations, we fit over-parameterized models to these future observations by optimizing an approximation of the desired expected loss function based on its sample counterpart and an adaptive duality function. The required imputation method is also developed using the same estimation technique with an adaptive m-out-of-n bootstrap approach. We illustrate its applications with the many-normal-means problem, n < p linear regression, and neural network-based image classification of MNIST digits. The numerical results demonstrate its superior performance across these diverse applications. While primarily expository, the paper conducts an in-depth investigation into the theoretical aspects of the topic. It concludes with remarks on some open problems.

Possible contributions of two nearby blazars to the NGC 4151 neutrino hotspot

The origin of the high-energy astrophysical neutrinos discovered by IceCube remains unclear, with both blazars and Seyfert galaxies emerging as potential sources. Recently, the IceCube Collaboration reported a $ ∼ σ$ neutrino signal from the direction of the nearby Seyfert galaxy NGC 4151. However, two gamma-ray-loud BL Lac objects, 4FGL 1210.3+3928 and 4FGL J1211.6+3901, lie close to NGC 4151, at angular distances of 0.08^∘ and 0.43^∘, respectively. We investigated the potential contribution of these two blazars to the observed neutrino signal from the direction of NGC 4151 and assessed their detectability with future neutrino observatories. We modeled the multiwavelength spectral energy distributions (SEDs) of both blazars using a self-consistent numerical radiation code, AM^3. We calculated their neutrino spectra and compared them to the measured NGC 4151 neutrino spectrum and future neutrino detector sensitivities. The SED of 4FGL 1210.3+3928 revealed a feature that cannot be explained with a purely leptonic model, suggesting the presence of protons in the jet. Our model predicts neutrino emission peaking above ∼10^17 eV with fluxes of $ ∼ erg cm^ s^ $ for this source. The SED of 4FGL J1211.6+3901 can be explained with both leptonic and leptohadronic models. The contribution of these two blazars to the ∼10 TeV neutrino signal observed from the direction of NGC 4151 can only be minor. Still, future radio-based neutrino telescopes such as IceCube-Gen2's radio array and GRAND may be able to detect high-energy neutrinos from these two potential neutrino sources.

Magnetic reconnection and energy extraction from a Konoplya–Zhidenko rotating non-Kerr black hole

Recently, magnetic reconnection has attracted considerable attention as a novel energy extraction mechanism, relying on the rapid reconnection of magnetic field lines within the ergosphere. We have investigated the properties of the energy extraction via magnetic reconnection in a Konoplya–Zhidenko rotating non-Kerr black hole spacetime with an extra deformation parameter. Our results show that the positive deformation parameter expands the possible region of energy extraction and improves the maximum power, maximum efficiency, and the maximum ratio of energy extraction between magnetic reconnection and the Blandford–Znajek process. This means that in the Konoplya–Zhidenko rotating non-Kerr black hole spacetime one can extract more energy via magnetic reconnection than in the Kerr black hole case. These effects of the deformation parameter may provide valuable clues for future astronomical observations of black holes and verification of gravity theories.

Predictions of Dust Continuum Emission from a Potential Circumplanetary Disk: A Case Study of the Planet Candidate AB Aurigae b

Abstract Gas-accreting planets embedded in protoplanetary disks are expected to show dust thermal emission from their circumplanetary disks (CPDs). However, a recently reported gas-accreting planet candidate, AB Aurigae b, has not been detected in (sub)millimeter continuum observations. We calculate the evolution of dust in the potential CPD of AB Aurigae b and predict its thermal emission at 1.3 mm wavelength as a case study, where the obtained features may also be applied to other gas-accreting planets. We find that the expected flux density from the CPD is lower than the 3σ level of the previous continuum observation by the Atacama Large Millimeter/submillimeter Array with broad ranges of parameters, consistent with a nondetection. However, the expected planet mass and gas accretion rate are higher if the reduction of the observed near-infrared continuum and Hα line emission due to the extinction by small grains is considered, resulting in higher flux density of the dust emission from the CPD at (sub)millimeter wavelengths. We find that the corrected predictions of the dust emission are stronger than the 3σ level of the previous observation with the typical dust-to-gas mass ratio of the inflow to the CPD. This result suggests that the dust supply to the vicinity of AB Aurigae b is small if the planet candidate is not the scattered light of the star but is a planet and has a CPD. Future continuum observations at shorter wavelengths are required to obtain more robust clues to the question of whether the candidate is a planet or not.

Bidirectional f-Divergence-Based Deep Generative Method for Imputing Missing Values in Time-Series Data.

Imputing missing values in high-dimensional time-series data remains a significant challenge in statistics and machine learning. Although various methods have been proposed in recent years, many struggle with limitations and reduced accuracy, particularly when the missing rate is high. In this work, we present a novel f-divergence-based bidirectional generative adversarial imputation network, tf-BiGAIN, designed to address these challenges in time-series data imputation. Unlike traditional imputation methods, tf-BiGAIN employs a generative model to synthesize missing values without relying on distributional assumptions. The imputation process is achieved by training two neural networks, implemented using bidirectional modified gated recurrent units, with f-divergence serving as the objective function to guide optimization. Compared to existing deep learning-based methods, tf-BiGAIN introduces two key innovations. First, the use of f-divergence provides a flexible and adaptable framework for optimizing the model across diverse imputation tasks, enhancing its versatility. Second, the use of bidirectional gated recurrent units allows the model to leverage both forward and backward temporal information. This bidirectional approach enables the model to effectively capture dependencies from both past and future observations, enhancing its imputation accuracy and robustness. We applied tf-BiGAIN to analyze two real-world time-series datasets, demonstrating its superior performance in imputing missing values and outperforming existing methods in terms of accuracy and robustness.

Deciphering Hypertriton and Antihypertriton Spins from Their Global Polarizations in Heavy-Ion Collisions.

Understanding the properties of hypernuclei is crucial for constraining the nature of hyperon-nucleon (Y-N) interactions, which plays a key role in determining the inner structure of compact stars. The lightest hypernuclei and antihypernuclei are the hypertriton (_{Λ}^{3}H), which consists of a pair of nucleons and a Λ hyperon, and its antinucleus (_{Λ[over ¯]}^{3}H[over ¯]). Significant knowledge has recently been acquired regarding the mass, lifetime, and binding energy of _{Λ}^{3}H. However, its exact spin, whether 1/2 or 3/2, remains undetermined in both experimental and theoretical studies. Here, we present a novel method of using the hypertriton global polarization in heavy-ion collisions to decipher not only its total spin but also its internal spin structure. This method is based on the finding that its three different spin structures exhibit distinct beam energy dependence of its global polarization when it is produced in these collisions from the coalescence of proton, neutron and Λ. Future observations of the hypertriton and antihypertriton global polarizations thus provide the opportunity to unveil the spin structures of hypertriton and antihypertriton and their production mechanisms in heavy-ion collisions.

Measuring the angular momentum of a neutron using Earth's rotation

A coupling between Earth's rotation and orbital angular momentum (OAM), known as the Sagnac effect, is observed in entangled neutrons produced using a spin-echo interferometer. After correction for instrument systematics the measured coupling is within 5% of theory, with an uncertainty of 7.2%. The OAM in our setup is transverse to the propagation direction and scales linearly with neutron wavelength (4–12.75 Å), so the Sagnac coupling can be varied without mechanically rotating the device, which avoids systematic errors present in previous experiments. The detected transverse OAM of our beam corresponds to 4098±295ℏÅ−1,105 times lower than in the previous neutron experiments. This demonstrates the feasibility of using the Sagnac effect to definitively measure neutron OAM and paves the way towards a future observation of the quantum Sagnac effect. Published by the American Physical Society 2025

Prospects for Observing High-redshift Radio-loud Quasars in the SKA Era: Paving the Way for 21 cm Forest Observations

Abstract The 21 cm forest is a sensitive probe for the early heating process and small-scale structures during the epoch of reionization (EOR), to be realized with the upcoming Square Kilometre Array (SKA). Its detection relies on the availability of radio-bright background sources, among which the radio-loud quasars are very promising, but their abundance during the EOR is still poorly constrained due to limited observations. In this work, we use a physics-driven model to forecast future radio-loud quasar observations. We fit the parameters of the model using observational data of high-redshift quasars. Assuming Eddington accretion, the model yields an average lifetime of t q ~ 105.5 yr for quasars at z ~ 6, consistent with recent results obtained from quasar proximity zone observation. We show that if the radio-loud fraction of quasars evolves with redshift, it will significantly reduce the abundance of observable radio-loud quasars in the SKA era, making 21 cm forest studies challenging. With a constant radio-loud fraction, our model suggests that a 1 yr sky survey conducted with SKA-LOW has the capability to detect approximately 20 radio-loud quasars at z ~ 9, with sufficient sensitivity to resolve individual 21 cm forest lines.

Rotational rate coefficients computation of MgS(X1Σ+) in collision with He(1S)

ABSTRACT Given its abundance in the interstellar medium recently justified by astronomical observations, the chemistry and reactivity of the metal-bearing molecule MgS require special attention. The availability of up-to-date collision data between this MgS molecule and the most abundant perturbing species H$_2$ and He in the interstellar medium is an essential resource to derive reliable values of its molecular abundance from astronomical observations. This work aims to provide improved scattering parameters for the MgS molecular system in collision with He. A new 2D potential energy surface (2D-PES) is derived by adopting the state-of-the-art level of theory of the explicitly correlated coupled cluster with single, double, and perturbative triple excitations (RCCSD(T)-F12) method in conjunction with the aug-cc-pVTZ basis sets. This PES was used to calculate inelastic cross-sections within the framework of the close-coupling (CC) theory for total energies $\le 500$ cm$^{-1}$ and J$\le 21$. Using the Maxwell–Boltzmann distribution of kinetic energies, these cross-sections were integrated to generate the collisional (de)-excitation rate coefficients for temperatures below 100 K. We expect that the new rate coefficients will help us to analyse present and future observations of this key molecule for the interstellar chemistry.