Charles A. Bowesman, Sergei N. Yurchenko, Ahmed F. Al-Refaie
et al.
The TIRAMISU code, a new program for computing on-the-fly non-LTE molecular spectra and opacities for solving self-consistent radiative transfer problems in exoplanet atmospheres, is presented. The ultra-hot Jupiter KELT-20 b is used as a case study to identify the wavelength regions at which non-LTE effects may be detectable. It is shown that upper atmospheric OH in vibrational non-LTE should be observable primarily via hot bands in the mid-infrared and enhanced photodissociation in the visible. Varying the abundance of OH in non-LTE demonstrates a nonlinear relationship between the abundance and the strength of non-LTE effects. Using recent calculations of the photodissociation probabilities of OH, it is shown that non-LTE effects can increase the total photodissociation rate by 2 orders of magnitude in the upper atmosphere, which is likely to have a significant impact on atmospheric and chemical modelling. Increases and reductions in the molecular opacities under non-LTE conditions may lead to the mischaracterization of molecular abundances in retrievals that only consider opacities computed under LTE. Collisional data requirements to support future non-LTE modeling for a variety of exoplanet atmospheres and across a wide range of wavelengths are discussed.
We report on follow-up observations with XMM-Newton, the FORS2 instrument at the ESO-VLT, and FAST, aiming to characterise the nature of five thermally emitting isolated neutron star (INS) candidates recently discovered from searches in the footprint of the Spectrum Roentgen Gamma (SRG)/eROSITA All-sky Survey. We find that the X-ray spectra are predominantly thermal and can be described by low-absorbed blackbody models with effective temperatures ranging from 50 to 210 eV. In two sources, the spectra also show narrow absorption features at 300–400 eV. Additional non-thermal emission components are not detected in any of the five candidates. The soft X-ray emission, the absence of optical counterparts in four sources, and the consequent large X-ray-to-optical flux ratios > 3000 − 5400 confirm their INS nature. For the remaining source, eRASSU J144516.0–374428, the available data do not allow a confident exclusion of an active galactic nucleus nature. However, if the source is Galactic, the small inferred X-ray emitting region is reminiscent of a heated pulsar polar cap, possibly pointing to a binary pulsar nature. X-ray timing searches do not detect significant modulations in all candidates, implying pulsed fraction upper limits of 13–19% (0.001–13.5 Hz). The absence of pulsations in the FAST observations targeting eRASSU J081952.1–131930 and eRASSU J084046.2–115222 excludes periodic magnetospheric emission at 1–1.5 GHz with an 8σ significance down to 4.08 μJy and 2.72 μJy, respectively. The long-term X-ray emission of all sources does not imply significant variability. Additional observations are warranted to establish exact neutron star types. At the same time, the confirmation of the predominantly thermal neutron star nature in four additional sources highlights the power of SRG/eROSITA to complement the Galactic INS population.
Kaan Çökerim, Henryk Dobslaw, Kyriakos Balidakis
et al.
Abstract Daily displacement time series from Global Navigation Satellite Systems (GNSS) are frequently used to study deformations of the Earth’s surface due to a wide range of different geophysical processes. The recorded deformations result from tectonic activity or non-tectonic processes like volcanism, groundwater fluctuations and atmospheric loading. In addition, local disturbances of the antenna (e.g., snow cover, thermoelastic effects of the monumentation) and artifacts from GNSS processing (e.g., draconitic signals) are sometimes prominently included in coordinate time series. We use a Temporal Convolution Network (TCN) to predict non-tectonic vertical GNSS displacements on a global scale from physics-based non-tidal loading products. We train our model on a global dataset with more than 11,000 GNSS stations from the Nevada Geodetic Laboratory, active from January 2002 until June 2024, and evaluate the performance against independent estimations. Across the hold-out dataset, our TCN derives non-tidal loading GNSS signatures that when compared to the non-tectonic GNSS signal results in a global average reduction in RMSE of 4.7 % with respect to the numerical non-tidal loading models. This approach presents an initial step towards a data-driven complement to physics-based numerical loading models, improving the isolation of non-tectonic signals in GNSS time series and validation of numerical non-tidal loading models. Graphical Abstract
Ultralight bosonic dark matter in its most general form can be detected through its decay or annihilation to a quasimonochromatic radio line. Assuming only that this line is consistent with the most general properties of the expected phase space of our Milky Way halo, we have developed and carried out a novel model-independent search for dark matter in the L and S bands. More specifically, the search selects for a line that exhibits a Doppler shift with position according to the solar motion through a static halo and similarly varies in intensity with position with respect to the Galactic center. Over the combined L - and S -band range 1020–2700 MHz, radiative annihilation of dark matter is excluded above 〈 σv 〉 ≈ 10 ^−30 cm ^3 s ^−1 , and for decay above λ ≈ 10 ^−32 s ^−1 .
Abstract The DAMA/LIBRA experiment has reported an annual modulation signal in NaI(Tl) detectors, which has been interpreted as a possible indication of dark matter interactions. However, this claim remains controversial, as several experiments have tested the modulation signal using NaI(Tl) detectors. Among them, the COSINE-100 experiment, specifically designed to test DAMA/LIBRA’s claim, observed no significant signal, revealing a more than 3σ discrepancy with DAMA/LIBRA’s results. Here we present COSINE-100U, an upgraded version of the experiment, which aims to expand the search for dark matter interactions by improving light collection efficiency and reducing background noise. The detector, consisting of eight NaI(Tl) crystals with a total mass of 99.1 kg, has been relocated to Yemilab, a new underground facility in Korea, and features direct PMT-coupling technology to enhance sensitivity. These upgrades significantly improve the experiment’s ability to probe low-mass dark matter candidates, contributing to the ongoing global effort to clarify the nature of dark matter.
Chaitanya Chawak, Francisco Villaescusa-Navarro, Nicolás Echeverri-Rojas
et al.
Recent works have discovered a relatively tight correlation between Ω _m and the properties of individual simulated galaxies. Because of this, it has been shown that constraints on Ω _m can be placed using the properties of individual galaxies while accounting for uncertainties in astrophysical processes such as feedback from supernovae and active galactic nuclei. In this work, we quantify whether using the properties of multiple galaxies simultaneously can tighten those constraints. For this, we train neural networks to perform likelihood-free inference on the value of two cosmological parameters (Ω _m and σ _8 ) and four astrophysical parameters using the properties of several galaxies from thousands of hydrodynamic simulations of the CAMELS project. We find that using properties of more than one galaxy increases the precision of the Ω _m inference. Furthermore, using multiple galaxies enables the inference of other parameters that were poorly constrained with one single galaxy. We show that the same subset of galaxy properties are responsible for the constraints on Ω _m from one and multiple galaxies. Finally, we quantify the robustness of the model and find that without identifying the model range of validity, the model does not perform well when tested on galaxies from other galaxy formation models.
Giulia Migliori, R. Margutti, B. D. Metzger
et al.
We present the first deep X-ray observations of luminous fast blue optical transient (LFBOT) AT 2018cow at ∼3.7 yr since discovery, together with the reanalysis of the observation at δ t ∼ 220 days. X-ray emission is significantly detected at a location consistent with AT 2018cow. The very soft X-ray spectrum and sustained luminosity are distinct from the spectral and temporal behavior of the LFBOT in the first ∼100 days and would possibly signal the emergence of a new emission component, although a robust association with AT 2018cow can only be claimed at δ t ∼ 220 days, while at δ t ∼ 1350 days contamination of the host galaxy cannot be excluded. We interpret these findings in the context of the late-time panchromatic emission from AT 2018cow, which includes the detection of persistent, slowly fading UV emission with ν L _ν ≈ 10 ^39 erg s ^−1 . Similar to previous works (and in analogy with arguments for ultraluminous X-ray sources), these late-time observations are consistent with thin disks around intermediate-mass black holes (with M _• ≈ 10 ^3 –10 ^4 M _☉ ) accreting at sub-Eddington rates. However, differently from previous studies, we find that smaller-mass black holes with M _• ≈ 10–100 M _☉ accreting at ≳the Eddington rate cannot be ruled out and provide a natural explanation for the inferred compact size ( R _out ≈ 40 R _☉ ) of the accretion disk years after the optical flare. Most importantly, irrespective of the accretor mass, our study lends support to the hypothesis that LFBOTs are accretion-powered phenomena and that, specifically, LFBOTs constitute electromagnetic manifestations of super-Eddington accreting systems that evolve to ≲Eddington over a ≈100-day timescale.
Abstract In this work, we investigate six helicity amplitudes of the four-body $$B_{(s)} \rightarrow (\pi \pi )(K\bar{K})$$ B ( s ) → ( π π ) ( K K ¯ ) decays via an angular analysis in the perturbative QCD (PQCD) approach. The $$\pi \pi $$ π π invariant mass spectrum is dominated by the vector resonance $$\rho (770)$$ ρ ( 770 ) together with scalar resonance $$f_0(980)$$ f 0 ( 980 ) , while the vector resonance $$\phi (1020)$$ ϕ ( 1020 ) and scalar resonance $$f_0(980)$$ f 0 ( 980 ) are expected to contribute in the $$K\bar{K}$$ K K ¯ invariant mass range. We extract the two-body branching ratios $$\mathcal{B}(B_{(s)}\rightarrow \rho \phi )$$ B ( B ( s ) → ρ ϕ ) from the corresponding four-body decays $$B_{(s)}\rightarrow \rho \phi \rightarrow (\pi \pi )(K \bar{K})$$ B ( s ) → ρ ϕ → ( π π ) ( K K ¯ ) based on the narrow width approximation. The predicted $$\mathcal{B}(B^0_{s}\rightarrow \rho \phi )$$ B ( B s 0 → ρ ϕ ) agrees well with the current experimental data within errors. The longitudinal polarization fractions of the $$B_{(s)}\rightarrow \rho \phi $$ B ( s ) → ρ ϕ decays are found to be as large as $$90\%$$ 90 % , basically consistent with the previous two-body predictions within uncertainties. In addition to the direct CP asymmetries, the triple-product asymmetries (TPAs) originating from the interference among various helicity amplitudes are also presented for the first time. Since the $$B_s^0\rightarrow \rho ^0\phi \rightarrow (\pi ^+\pi ^-)(K^+K^-)$$ B s 0 → ρ 0 ϕ → ( π + π - ) ( K + K - ) decay is induced by both tree and penguin operators, the values of the $$\mathcal{A}^\textrm{CP}_\textrm{dir}$$ A dir CP and $$\mathcal{A}^{1}_{\text {T-true}}$$ A T-true 1 are calculated to be $$(21.8^{+2.7}_{-3.3})\%$$ ( 21 . 8 - 3.3 + 2.7 ) % and $$(-10.23^{+1.73}_{-1.56})\%$$ ( - 10 . 23 - 1.56 + 1.73 ) % respectively. While for pure penguin decays $$B^0\rightarrow \rho ^0\phi \rightarrow (\pi ^+\pi ^-)(K^+K^-)$$ B 0 → ρ 0 ϕ → ( π + π - ) ( K + K - ) and $$B^+\rightarrow \rho ^+\phi \rightarrow (\pi ^+\pi ^0)(K^+K^-)$$ B + → ρ + ϕ → ( π + π 0 ) ( K + K - ) , both the direct CP asymmetries and “true” TPAs are naturally expected to be zero in the standard model (SM) due to the absence of the weak phase difference. The “fake” TPAs requiring no weak phase difference are usually none zero for all considered decay channels. The sizable “fake” $$\mathcal{A}^{1}_{\text {T-fake}}=(-20.92^{+6.26}_{-2.80})\%$$ A T-fake 1 = ( - 20 . 92 - 2.80 + 6.26 ) % of the $$B^0\rightarrow \rho ^0\phi \rightarrow (\pi ^+\pi ^-)(K^+K^-)$$ B 0 → ρ 0 ϕ → ( π + π - ) ( K + K - ) decay is predicted in the PQCD approach, which provides valuable information on the final-state interactions. The above predictions can be tested by the future LHCb and Belle-II experiments.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
Samidha Shetty, Gordon Brittan, Prasanta S. Bandyopadhyay
Empirical Bayes-based Methods (<i>EBM</i>) is an increasingly popular form of Objective Bayesianism (<i>OB</i>). It is identified in particular with the statistician Bradley Efron. The main aims of this paper are, first, to describe and illustrate its main features and, second, to locate its role by comparing it with two other statistical paradigms, Subjective Bayesianism (<i>SB</i>) and Evidentialism<i>. EBM</i>’s main formal features are illustrated in some detail by schematic examples. The comparison between what Efron calls their underlying “philosophies” is by way of a distinction made between confirmation and evidence. Although this distinction is sometimes made in the statistical literature, it is relatively rare and never to the same point as here. That is, the distinction is invariably spelled out intra- and not inter-paradigmatically solely in terms of one or the other accounts. The distinction made in this paper between confirmation and evidence is illustrated by two well-known statistical paradoxes: the base-rate fallacy and Popper’s paradox of ideal evidence. The general conclusion reached is that each of the paradigms has a basic role to play and all are required by an adequate account of statistical inference from a technically informed and fine-grained philosophical perspective.
Vassilis Amiridis, Stelios Kazadzis, Antonis Gkikas
et al.
The Mediterranean, and particularly its Eastern basin, is a crossroad of air masses advected from Europe, Asia and Africa. Anthropogenic emissions from its megacities meet over the Eastern Mediterranean, with natural emissions from the Saharan and Middle East deserts, smoke from frequent forest fires, background marine and pollen particles emitted from ocean and vegetation, respectively. This mixture of natural aerosols and gaseous precursors (Short-Lived Climate Forcers—SLCFs in IPCC has short atmospheric residence times but strongly affects radiation and cloud formation, contributing the largest uncertainty to estimates and interpretations of the changing cloud and precipitation patterns across the basin. The SLCFs’ global forcing is comparable in magnitude to that of the long-lived greenhouse gases; however, the local forcing by SLCFs can far exceed those of the long-lived gases, according to the Intergovernmental Panel on Climate Change (IPCC). Monitoring the spatiotemporal distribution of SLCFs using remote sensing techniques is important for understanding their properties along with aging processes and impacts on radiation, clouds, weather and climate. This article reviews the current state of scientific know-how on the properties and trends of SLCFs in the Eastern Mediterranean along with their regional interactions and impacts, depicted by ground- and space-based remote sensing techniques.
In order to explore the effect of entropy layer on swept shock/turbulent boundary layer interaction, numerical simulation was applied to study a fin/blunt plate physical model. The results show that the thickness of the entropy layer upstream of the swept shock wave increases with the increase of the passivation radius at the leading edge of the plate, and the thickness of the boundary layer also increases with the increase of the thickness of the entropy layer. The introduction of the entropy layer does not change the quasi-conical similarity of swept shock/turbulent boundary layer interaction, nor does it change the position of VCO. It only changes the angle of upstream influence line and separation line. As the thickness of the entropy layer increases, the scales of the conical main vortex and the corner vortex formed by the swept shock/turbulent boundary layer interaction increase. The upstream entropy layer increases the total pressure loss in the downstream swept shock/turbulent boundary layer interaction region, but the relative total pressure loss caused by swept shock/turbulent boundary layer interaction is not affected by the upstream entropy layer.
We present a comprehensive analysis of a very long-period (124.93669 days) eclipsing binary KIC 9028474, which is composed of F9V+G1V components on a highly eccentric ( e = 0.82029) orbit. Masses and radii of the primary and the secondary components are M _1 = 1.18 ± 0.04 M _⊙ , M _2 = 1.04 ± 0.03 M _⊙ , R _1 = 1.52 ± 0.02 R _⊙ , and R _2 = 1.11 ± 0.01 R _⊙ , respectively. Eclipse time variations show the presence of apsidal motion, which in turn shows the existence of a third body in a relatively close orbit. Simultaneous analysis of infrared spectra and space photometry reveals that the primary component is about to leave the main sequence, indicating an age of 5.2 ± 0.8 Gyr for the system. Theoretical evaluation of the observed eccentricity indicates that the components of KIC 9028474 will end their whole life much before the orbital circularization is achieved. Given the limited resolution of the spectra, we can only place an upper limit on the rotational velocities of each star, thus a theoretical evaluation of the synchronization of the components.
Abstract We calculate the rate of double parton scattering (DPS) in proton-proton collisions in the framework of the recently proposed hot spot model of the nucleon structure. The resulting rate, especially for the case of three hot spots, is compared with the current experimental data on DPS at the LHC.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
Using the nucleon coalescence model based on kinetic freeze-out nucleons from the 3D MUSIC+UrQMD and the 2D VISHNU hybrid model with a crossover equation of state, we study the multiplicity dependence of deuteron (d) and triton (t) production from central to peripheral Au+Au collisions at sNN= 7.7, 14.5, 19.6, 27, 39, 62.4 and 200 GeV and Pb+Pb at sNN=2.76 TeV, respectively. It is found that the ratio NtNp/Nd2 of the proton yield Np, deuteron yield Nd and triton yield Nt exhibits a scaling behavior in its multiplicity dependence, i.e., decreasing monotonically with increasing charged-particle multiplicity. A similar multiplicity scaling of this ratio is also found in the nucleon coalescence calculation based on kinetic freeze-out nucleons from a multiphase transport (AMPT) model. The scaling behavior of NtNp/Nd2 can be naturally explained by the interplay between the sizes of light nuclei and the nucleon emission source. We further argue that the multiplicity scaling of NtNp/Nd2 can be used to validate the production mechanism of light nuclei, and the collision energy dependence of this yield ratio can further serve as a baseline in the search for the QCD critical point in relativistic heavy-ion collisions.
Fiona Bairstow, Sven Gastauer, Sven Gastauer
et al.
Antarctic krill are subject to precautionary catch limits, based on biomass estimates, to ensure human activities do not adversely impact their important ecological role. Accurate target strength models of individual krill underpin biomass estimates. These models are scaled using measured and estimated distributions of length and orientation. However, while the length distribution of a krill swarm is accessible from net samples, there is currently limited consensus on the method for estimating krill orientation distribution. This leads to a limiting factor in biomass calculations. In this work, we consider geometric shape as a variable in target strength calculations and describe a practical method for generating a catalog of krill shapes. A catalog of shapes produces a more variable target strength response than an equivalent population of a scaled generic shape. Furthermore, using a shape catalog has the greatest impact on backscattering cross-section (linearized target strength) where the dominant scattering mechanism is mie scattering, irrespective of orientation distribution weighting. We suggest that shape distributions should be used in addition to length and orientation distributions to improve the accuracy of krill biomass estimates.
Science, General. Including nature conservation, geographical distribution
The ALICE collaboration, S. Acharya, D. Adamová
et al.
Abstract Inclusive J/ψ yields and average transverse momenta in p-Pb collisions at a center-of-mass energy per nucleon pair s NN $$ \sqrt{s_{\mathrm{NN}}} $$ = 8.16 TeV are measured as a function of the charged-particle pseudorapidity density with ALICE. The J/ψ mesons are reconstructed at forward (2.03 < y cms < 3.53) and backward (−4.46 < y cms < −2.96) center-of-mass rapidity in their dimuon decay channel while the charged-particle pseudorapidity density is measured around midrapidity. The J/ψ yields at forward and backward rapidity normalized to their respective average values increase with the normalized charged-particle pseudorapidity density, the former showing a weaker increase than the latter. The normalized average transverse momenta at forward and backward rapidity manifest a steady increase from low to high charged-particle pseudorapidity density with a saturation beyond the average value.
Nuclear and particle physics. Atomic energy. Radioactivity