Astrophysics of Galaxies
Distribution of the magnetic field relative to the plane of the Galaxy in the region of the Sagittarius spiral arm
R.R. Andreasyan, H.R. Andreasyan, A. M. Mickaelian et al. (+2 more)
Faraday rotation data for 492
pulsars and more than 2,700 extragalactic
radio sources were used to study the
magnetic field, in detail, in the direction of
Galactic longitude $33^o$ <l< $63^o$, which partially covers the Sagittarius spiral arm region. It was proposed that the Sagittarius spiral arm lies north of the h=-300 pc plane, where h is the distance from the
Galactic plane. The (-) sign indicates that this plane is located in the southern hemisphere of the
Galaxy. The
magnetic field of the Sagittarius spiral arm is directed toward the Sun. This direction is close to the direction of the
magnetic field of the northern hemisphere
halo. The small absolute value of the rotation measures in the region south of the h=-300 pc plane is due solely to the contribution of the
magnetic field of the southern hemisphere
halo, which is directed opposite to the field of the northern hemisphere
halo and the direction of the field in the Sagittarius arm. In the interarm region between the local Orion arm and the Sagittarius arm, the
halo magnetic field extends to the
Galactic plane, where a reversal of the
magnetic fields of the
halos of the northern and southern hemispheres occurs.
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All authors R.R. Andreasyan, H.R. Andreasyan, A. M. Mickaelian, A.G. Suqiasyan, G.M. Paronyan
Strongly Correlated Electrons
Finite-temperature Lanczos for anisotropic spin systems using triple-hybrid high-performance computing
J. Schnack
Lanczos concepts are often realized on supercomputers. In view of modern architectures of high-performance computing triple-hybrid schemes employing MPI, CPU-openMP as well as GPU-openMP should be utilized. The present article sketches how such a scheme could be utilized in order to meet the demands of the finite-temperature Lanczos method for anisotropic
spin systems.
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Geophysics
Crustal and upper mantle model of the Middle East based on full-waveform inversion
R{\i}dvan Örsvuran, Ebru Bozdağ, Daniel Peter et al. (+7 more)
We present MEAD-M20, a new tomographic model of the Middle East and its surrounding regions, including Anatolia, Iran, and the Caucasus. The model is developed within a full-waveform inversion framework, based on 3D wavefield simulations and the adjoint method, after 20 iterations, utilizing an extensive
dataset from permanent and temporary stations available from EarthScope and regional networks. Starting from the global FWI model GLAD-M25 on a 60{\deg}x 60{\deg} regional mesh, we invert 210 regional earthquakes recorded by 1,215 stations to obtain the P- and S-wave model with transverse isotropy in the upper mantle. For the first 12 iterations, we combine multitaper traveltime measurements of 15-50 s body waves and 50-100 s body and surface waves on three components. We use a refined crustal mesh to better sample the crust after the 12th iteration and gradually decrease the minimum surface-wave period to 30 s. MEAD-M20 provides a self-consistent P- and S-wave model ready for seismic wave simulations, which is essential for accurate earthquake location, source parameter estimation, and seismic hazard assessment in the geologically and tectonically complex region. MEAD-M20 reveals several important geodynamical and tectonic features, including local mantle plumes beneath the Arabian Plate, Jordan, and the Levant, characterized by low-velocity anomalies and likely associated with volcanism in the Harrats, Jordan, and the Karacadag regions. In addition to the active subduction and rifting in the area, the model clearly identifies remnants of the Tethys Ocean beneath Eastern Anatolia, which become progressively shallower toward the Makran region in the south, consistent with the subduction history along the Bitlis-Zagros suture zone. We also observe lithospheric-scale low-velocity anomalies associated with the North and East Anatolian faults, extending to depths of approximately 200 km.
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All authors R{\i}dvan Örsvuran, Ebru Bozdağ, Daniel Peter, Daniel Peter, Andrea Chiang, Rengin Gök, Yahya M. Tarabulsi, Ahmed Hosny, Khalid Yousef, Abdullah Mousa
Soft Condensed Matter
Stress Drops Associated with Surface Crack Formation in Photo-aged Polypropylene during Three-Point Bending
Kazuya Haremaki, Yusuke Koide, Takashi Uneyama et al. (+2 more)
Using three-point bending, this study investigates surface-crack formation in photo-aged polypropylene (PP) that has a depth-dependent aging gradient. PP undergoes embrittlement under ultraviolet (UV) irradiation, and because the photo-oxidation proceeds inward from the irradiated surface, the embrittlement develops non-uniformly across the specimen thickness. PP specimens were mildly photo-aged by UV irradiation and had not yet developed visible surface cracks. Each specimen was bent in two configurations: with the UV-irradiated ("aged") surface on the tensile side, and with the opposite ("reverse") surface on the tensile side. When the aged surface was on the tensile side, the stress-strain curves exhibited several discrete stress drops, and in-situ side-view observation confirmed that the formation of each new surface crack coincided with a stress drop. In contrast, no clear stress drops were observed when the reverse surface was on the tensile side. These results show that the through-thickness gradient of embrittlement is directly reflected in the bending stress-strain response. Uniaxial tensile testing, the standard method for evaluating mechanical properties, formally assumes a nominally uniform deformation across the cross-section and therefore reflects the spatially averaged response. Three-point bending, by contrast, imposes the largest tensile strain at the specimen surface and thus selectively probes the embrittled surface layer, making it an effective method for detecting the surface embrittlement of photo-aged
polymers.
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All authors Kazuya Haremaki, Yusuke Koide, Takashi Uneyama, Yuichi Masubuchi, Takato Ishida
Physics Education
Establishing a national masters̀ programme in high-energy physics: lessons from a Romanian case study
Roxana Zus, Călin Alexa, Paul Grăvilă et al. (+2 more)
The establishment of a joint coordinated national programme for graduate education represents a significant step in strengthening higher education systems and their
alignment with international research environments. This paper examines the creation of the Romanian National Masters̀ Programme in High-Energy Physics, the first initiative of its kind in the country. We outline the motivation for its development, based on the need to prepare students for active participation in large-scale international collaborations such as CERN, while also consolidating domestic expertise. The article describes the programmes̀ design, including its multi-institutional structure, curriculum, and integration of research training, as well as the policy and administrative processes that enabled its implementation. Initial outcomes highlight the programmes̀ contribution to student mobility, research engagement, and capacity building within the Romanian higher education system. Finally, we discuss lessons learned and future perspectives, situating the initiative within broader European efforts to modernise graduate education in the sciences.
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All authors Roxana Zus, Călin Alexa, Paul Grăvilă, Zsolt-Iosif Lázár, Daniel Radu
High Energy Astrophysical Phenomena
Progenitor and Explosion Mechanism of 3C 397 Indicated from XRISM High-resolution Spectroscopy of Fe-group Elements
Hiroshi Nakajima, Yuken Ohshiro, Shing-Chi Leung et al. (+8 more)
We present spatially resolved X-ray spectroscopy of the Type Ia
supernova remnant 3C 397, one of the most promising candidates to have originated from a white
dwarf with a mass close to the Chandrasekhar limit. The remnant was observed during the performance verification phase of the X-ray Imaging and Spectroscopy Mission (XRISM), with the field of view of the Resolve calorimeter array positioned on the eastern half of the remnant. We divide the Resolve field of view into southeastern and northeastern regions and extract spectra from each region for both Resolve and Xtend. The Resolve spectra are characterized by narrow K-shell emission lines from intermediate-mass elements (IMEs) such as Si, S, Ar, and Ca, and by broader K-shell emission lines from iron-group elements (IGEs) such as Cr, Mn, Fe, and Ni. K-shell emission lines from Ti and Cr are also detected, and are found to be locally enhanced in the southeastern region, as reported in previous observations. We model the Resolve and Xtend spectra simultaneously by a non-
equilibrium ionization (NEI)
plasma model with multiple temperatures and ionization states. The observed mass ratios of Ti/Fe and Cr/Fe in the southeastern region can only be explained by nucleosynthesis in a
neutron-rich environment produced by electron-capture reactions in the innermost layers of the exploding white
dwarf. By comparing the observed mass ratios with those predicted by nucleosynthesis models, we constrain the central density to be >= 4.0 x 10^9 g cm^{-3} for the deflagration-to-detonation transition model and >= 6.0 x 10^9 g cm^{-3} for the pure turbulent deflagration model. On the other hand, the observed Ni/Fe mass ratio is globally enhanced across the field of view, suggesting an additional neutronization mechanism beyond electron-capture reactions, such as a higher progenitor
metallicity.
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All authors Hiroshi Nakajima, Yuken Ohshiro, Shing-Chi Leung, Koji Mori, Yoshiaki Kanemaru, Yoshitomo Maeda, Hiroya Yamaguchi, Masayoshi Nobukawa, Kumiko Nobukawa, Manabu Ishida, Yuichiro Ezoe
Quantum Physics
Interaction-Endowed PT-Symmetry and its Effects on Decoherence, Einselection, and Non-Markovianity in a Central Spin Model
Leoj Phoebe M. Esquierdo, Lemuel John F. Sese and Rayda P. Gammag
We have introduced PT-
symmetry to a central
spin model by adding a PT-symmetric interaction with a tunable hermiticity parameter $\gamma$. Using the pseudo-Hermitian formalism, we applied a Dyson map to transform the non-Hermitian
Hamiltonian to its Hermitian representation. We have found that the decoherence slows down as $\gamma$ increases, eventually ceasing at $\gamma=1$. We define a pseudo-Hermitian observable that commutes with the metric operator to add as the self-
Hamiltonian. Einselection gradually forced the system to select the eigenstates of the self-
Hamiltonian as $\gamma\rightarrow1$. The steady-state purity of the central
spin states in the strong environment regime exhibits a paradoxical decrease as $\gamma$ increases. However, a turning point (minimum) corresponding to a maximum information dissipation to the
spin bath is found. Finally, the Breuer-Laine-Piilo (BLP) measure, which is used to quantify the non-Markovianity of a
quantum system, was evaluated for a finite time. The BLP measure in the strong environment regime exhibited similar turning point behavior, which means that the information backflow reaches a saturation point before declining. This decline signifies the point where PT-
symmetry starts shielding the central
spin from the environment.
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Soft Condensed Matter
Lipid-Mediated Control of Thermally Induced Shape Transformations in Liquid Crystal Droplets
Mengwei Li and Lisa Tran
Lipids and
liquid crystals provide a useful platform for addressing how molecular-scale organization is translated into mesoscale shape transformation. Variations in hydrocarbon-chain packing can modify interfacial order, anchoring conditions, and elastic stresses, potentially coupling molecular organization to droplet morphology. Here, we investigate the temperature-dependent structural
evolution of monoolein-doped 4-octyl-4'-cyanobiphenyl (8CB) droplets dispersed in aqueous phospholipid solutions. Using polarized optical microscopy, we show that the internal monoolein concentration and the external lipid environment jointly regulate phase transitions, thin filamentation, and larger deformations during heating. The droplets undergo coupled smectic-nematic-isotropic transitions, with extended thin filaments observed exclusively in the smectic regime. At the smectic-to-nematic transition, we observe an abrupt and discontinuous onset of droplet shape deformation, revealing a shape-change transition coupled to the bulk mesophase transition. To our knowledge, this is the first report of a discontinuous droplet-shape-change transition coincident with a smectic-to-nematic phase transition. Varying the internal and external lipid contents redirects the reconfiguration pathway between filament-dominated smectic responses and more amorphous nematic shape changes. Interfacial tension measurements further show that stronger reductions in
liquid-
crystal-aqueous interfacial tension do not necessarily produce filamentation or deformation. Instead, the observed morphodynamics arise from the coupling between bulk elasticity, mesophase structure, and lipid-mediated interfacial organization. These findings establish lipid composition and hydrocarbon-chain architecture as key parameters governing thermally induced shape transformations in
liquid crystal droplets.
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Quantum Gases
Dimensional crossover in ultradilute Bose-Bose liquid mixtures
Leandra Vranješ Markić, Ivan Poparić, Krešimir Dželalija et al. (+2 more)
We study ultradilute $^{39}$K Bose-Bose bulk mixtures and droplets in an external harmonic potential that confines them in one spatial direction towards the two-dimensional (2D) limit. Equations of state for several confinements are obtained with
quantum Monte Carlo (QMC) at $T=0$, using interaction potentials that include information on the $s$-wave scattering length $a$ and the effective range $r_{\rm eff}$. Performing the calculations using two different interaction potential models we have determined the range of confinements for which equations of state are universal in terms of $a$ and $r_{\rm eff}$. Based on the QMC equation of state, we develop a 2D QMC density functional for each confinement strength and use it together with the local density approximation to determine properties of the self-bound drops. For moderate squeezing, energies and droplet profiles obtained using the 2D QMC functional agree well with those obtained using 3D functionals, while offering a substantial reduction in computational cost, and a consistent approach in crossover to 2D. Noticeably, our results approach 2D mean-field (MF) + Lee-Huang-Yang (LHY) predictions only for the most strongly confined systems for which universality in terms of $a$ and $r_{\rm eff}$ is observed. This implies a very narrow range of confinements for which 2D LHY functionals are applicable, which affects the study of
vortices using 2D functionals.
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All authors Leandra Vranješ Markić, Ivan Poparić, Krešimir Dželalija, Petar Stipanović, Jordi Boronat
Solar and Stellar Astrophysics
V407 Vul: a triple star system with an AM CVn detectable by gravitational wave observatories
James Munday, Antonio C. Rodriguez, Nicole Reindl et al. (+23 more)
The AM CVn class includes mass transferring, ultra-compact double white
dwarf binaries with orbital periods on the timescale of minutes. A long-standing puzzle is that none of the roughly fifty ultra-compact, "verification binaries" which are easily detectable in the millihertz gravitational wave regime reside in a triple
star configuration. Much evidence has hinted at V407 Vul being an inspiraling, double white
dwarf AM CVn with an orbital period of 569s. Yet, a decisive confirmation has proved challenging since a main sequence
star dominates its visible spectrum. We present a clear confirmation of the triple
star nature of the source by detecting a significant astrometric wobble of the photocentre on the 569s orbital period of the binary. The AM CVn and the main sequence components are gravitationally bound with a spatial separation of roughly 0.03-0.04”, equating to an orbital separation of approximately 120AU. A total of 23 years of orbital timing constrained the orbital decay of the AM CVn as being precise to the 1% level, critical in understanding if this class of binary survives through a period minimum or coalesce. New Hubble Space
Telescope ultra-violet imaging and spectroscopic data allowed the isolated detection of the AM CVn at shorter wavelengths, revealing an approximately 58000 K accretor white
dwarf, while placing a firm distance constraint of 3510+140-110 pc. At this distance, we predict that the
Laser Interferometer Space
Antenna (LISA) will detect V407 Vul with a 28.4+-9.2 signal-to-noise ratio in a 4yr mission time, making it the first verification binary with an outer tertiary, or "verification triple", detectable for millihertz gravitational wave observatories.
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All authors James Munday, Antonio C. Rodriguez, Nicole Reindl, Nina Mackensen, Tin Long Sunny Wong, S.P. Littlefair, Ingrid Pelisoli, Alex Brown, N. Castro Segura, Joheen Chakraborty, Harry Dawson, V. S. Dhillon, Matti Dorsch, Martin Dyer, James A. Garbutt, Stephan Geier, Matthew Green, Dan Jarvis, Mark R. Kennedy, Paul Kerry, James McCormac, Steven G. Parsons, Jan van Roestel, Dave Sahman, P.-E. Tremblay, Amalie Yates
Plasma Physics
HIR: A collisional-radiative model for hydrogen ionization in plasma with anisotropic fast ions
Sergey Polosatkin
The paper presents the HIR (Hydrogen Ionization Rates) software package developed for calculating the level populations of atomic hydrogen and the dynamics of its ionization in hot
plasma, including the case of fast ions with an anisotropic distribution function. The code is based on a steady-state collisional-radiative model that includes electron and ion impact excitation, de-excitation, ionization, charge exchange, and spontaneous radiative transitions. It is demonstrated that stepwise ionization via excited states contributes up to 20% to the total ionization rate and requires including levels up to the principal
quantum number N=8. For the GDML and GOL-NB mirror trap facilities, the effects of stepwise ionization on the mean free path of fast atoms are analyzed. It is shown that collisions with different
plasma species are non-additive due to stepwise ionization, leading to a reduction in the mean free path by up to 7% at 40 keV. The anisotropy of the fast ion distribution is found to have a negligible effect (less than 1%) on the ionization dynamics in the GDML
plasma. The ionization cost of hydrogen atoms in the GOL-NB
plasma is calculated, demonstrating a strong dependence on
plasma density due to competition between collisional and radiative de-excitation. The HIR package is openly available on GitHub.
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Optics
The Information Rate of Fiber-Wireless Communication Systems Based on Photonic Generation of RF Signals
Long Huang and Jianping Yao
High-capacity fiber-wireless communication systems operating at high frequencies increasingly rely on photonic generation of
radio-frequency (RF) signals. In these systems, optical signals are transmitted over optical fibers and detected by photodetectors, where RF signals are generated at frequencies equal to the difference between the optical carrier frequencies. A major performance-limiting impairment is the phase noise of the generated RF signals, which originates from the phase noise of the optical sources. In this paper, we develop comprehensive probabilistic models for the two principal configurations of fiber-wireless communication systems employing photonic RF generation. Based on these models, we propose an efficient numerical framework for calculating the information rate (IR). Numerical simulations are performed to validate the efficiency of the proposed
algorithm and the results provide design guidelines for high-performance fiber-wireless systems.
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Earth and Planetary Astrophysics
The Influence of Dust Composition on Accretion Outbursts
Nicolas Kaufmann, Anna B.T. Penzlin, Alfie Robinson et al. (+3 more)
Context: Episodic
accretion outbursts have been shown to occur in protoplanetary discs due to thermal instability at the inner edge of the dead zone. These outbursts periodically heat up the dead zone, significantly altering the composition/chemistry and
accretion onto the
star. Aims: We investigate how these
accretion outbursts affect the inner disc composition and how different
dust compositions and properties affect the outbursts' dynamics. Methods: We run vertically integrated axis-symmetric
dust and gas
evolution models using the TriPoD method, including
dust opacity dependent heating and cooling, a dead zone model, and compositional tracking of
dust, including the evaporation and condensation of volatiles. Results: When considering
dust to be made up of a condensation sequence of silicates and volatiles, the outburst evaporates most of the
dust within 0.5 au. The fast re-condensation and subsequent viscous
evolution reset the disc between bursts. Additionally, we find that the burst cycle period and maximal
accretion rate directly correlate with the
dust sublimation temperature.
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All authors Nicolas Kaufmann, Anna B.T. Penzlin, Alfie Robinson, Alexandros Ziampras, Tilman Birnstiel, Richard Booth
High Energy Astrophysical Phenomena
Timing and Spectral Analysis of the 2024 Outburst of 2S 1553$-$542 with NuSTAR and NICER
Haifan Zhu, Wei Wang, Wen Yang et al. (+4 more)
We report a timing and spectral study of the 2024 outburst of the Be/X-ray binary
pulsar 2S~1553$-$542 using NuSTAR and NICER observations. From the NuSTAR light curve we measure a pulse period of $9.285022\pm0.000001$~s. The energy-resolved pulse profiles are dominated by a single peak and show a wing-like structure most clearly in the $12$–$22$~keV band. The pulsed fraction remains above 60% and increases with energy. The phase-averaged NuSTAR spectrum is described by an absorbed blackbody plus cutoff power-law continuum, together with an iron emission line and a cyclotron absorption feature. Using the cyclabs model, we obtain a cyclotron energy of $E_{\rm cyc}\simeq24.1$~keV, corresponding to a
magnetic field strength of $B\sim3\times10^{12}$~G. Phase-resolved spectroscopy shows that the continuum and cyclotron-line parameters vary with pulse phase, and that the line becomes poorly constrained around the pulse-wing phase. We also searched the short NICER GTIs for transient mHz variability using wavelet analysis and a CEEMDAN-based
Hilbert–Huang transform. Localized excesses near $\sim10$~mHz and $\sim20$~mHz are found, but the short exposures, COI effects, red-noise fluctuations, and the lack of a well-constrained
Fourier peak limit their significance. We therefore treat them as candidate mHz variability rather than firm mHz QPO detections.
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All authors Haifan Zhu, Wei Wang, Wen Yang, Mariano Mendez, Chenxu Gao, Ziyi Xu, Pengfu Tian
Quantum Physics
Collective states of multi-level emitters: The role of multi-level interferences
Nathan E. Rahat and Christiane P. Koch
We explore how collective states of light and matter differ when the multi-level nature of the
quantum emitters is fully taken into account. For closely spaced emitters, interferences between near-resonant transitions completely change the character of the collective states compared to two-level approximations. In particular, we find a lower bound on the emitter separation for superradiance to occur which does not exist for two-level emitters. By contrast, for larger separations between the emitters, the collective states resemble those obtained within the widely used two-level approximation of the emitters. Both regimes may be realized by molecules trapped in optical
lattices. We therefore propose molecular candidates and describe experimental signatures of emerging multi-level interference.
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High Energy Astrophysical Phenomena
Fast optical spectroscopic observations of PSR J1023+0038 over one orbital period
M. M. Messa, M. C. Baglio, P. D'Avanzo et al. (+8 more)
Transitional millisecond
pulsars (tMSPs) are
neutron-
star binaries that switch between rotation-powered and
accretion-powered states, providing a key link between low-mass X-ray binaries and millisecond
radio pulsars. In their sub-luminous disc state, these systems exhibit complex variability whose origin is still debated. We present high-time-resolution optical spectroscopic observations of the tMSP PSR J1023+0038 obtained during its sub-luminous disc state. Our
dataset covers for the first time a full orbital cycle at minute-timescale cadence. We detect significant variability in the main properties of the optical emission lines, including the equivalent width (EW) and full width at half maximum (FWHM), on timescales of minutes. A comparison between the temporal
evolution of these quantities reveals indications of correlated behaviour, with some FWHM minima coinciding with decreases in the EW. This may point to episodes of matter ejection from the inner regions of the
accretion disc, possibly associated with switches to low modes. The Doppler
tomography of the H$\alpha$ and H$\beta$ emission lines suggests the presence of asymmetric emission structures, consistent with a scenario in which part of the accreting material is expelled from the system. In addition, the optical continuum shows variability consistent with a possible orbital modulation associated with the irradiated companion
star, although its characterisation is limited by the observing conditions. Our results provide new constraints on the short-timescale behaviour of tMSPs in the sub-luminous disc state and support scenarios in which
accretion and
outflow processes coexist. Further multiwavelength observations, particularly including simultaneous X-ray coverage, will be crucial to establish a direct link between the observed optical variability and the high/low mode switches.
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All authors M. M. Messa, M. C. Baglio, P. D'Avanzo, G. Illiano, F. Coti Zelati, K. Alabarta, D. de Martino, Y. D. Hu, A. Miraval Zanon, A. Reguitti, S. Campana
Earth and Planetary Astrophysics
Cloud and ammonia vertical profiles in the equatorial atmosphere of Jupiter determined from visible to near-IR observations made by VLT/MUSE, Cassini/VIMS, IRTF/SpeX and Juno/JIRAM
Patrick G. J. Irwin, Asier Anguiano-Arteaga, Michelle Colantoni et al. (+8 more)
We present a combined cloud/ammonia model for Jupiter's equatorial atmosphere from 0.1 to 10 bar, consistent with observations made at a range of observation geometries from 0.35 to 5.15 $\mu$m by VLT/MUSE, Cassini/VIMS, IRTF/SpeX and Juno/JIRAM. Our cloud model has three components: 1) an optically-thick lower cloud (radius $r$$\sim$$10$ $\mu$m) at 1-2 bar; 2) an optically-thin upper cloud ($r$$\sim$$10$ $\mu$m) at $\sim$0.55 bar; and 3) a layer of blue-absorbing chromophore particles ($r$$\sim$$0.2$ $\mu$m) situated within the main lower cloud. The ammonia profile is intimately linked with the cloud profile with the lower cloud coinciding with an initial drop in ammonia abundance and the upper cloud coinciding with the ammonia condensation level. The large lower cloud particles are highly scattering at visible wavelengths, allowing sunlight to scatter through the clouds and be Rayleigh-scattered from the deep atmosphere. At 5 $\mu$m, the lower cloud particles are found to be more absorbing, with the belt/zone differences mostly accounted for by changes in the single-scattering albedo of these particles and secondarily by changes in the cloud opacity. The spectral properties of these lower cloud particles are possibly consistent with a component of water ice. The upper cloud particles need a distinct absorption band near 3 $\mu$m, possibly consistent with a component of ammonia ice. We note that we do not need a separate upper-level photochemical haze in our model. Instead, we find that the features seen at methane-absorbing wavelengths are caused by variations in the opacity and vertical extent of the upper cloud layer.
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All authors Patrick G. J. Irwin, Asier Anguiano-Arteaga, Michelle Colantoni, Joseph Penn, Santiago Pérez-Hoyos, Davide Grassi, Alessandro Mura, Charlotte L. B. Alexander, Leigh N. Fletcher, Simon C. A. Toogood, Michael T. Roman
Cosmology and Nongalactic Astrophysics
No preference for generalized emergent dark energy from current cosmological data
Vipin Kumar Sharma, Himanshu Chaudhary, Salvatore Capozziello et al. (+2 more)
In this work, we revisit the generalized emergent dark energy model by confronting it with DESI DR2
baryon acoustic oscillation measurements, in combination with joint CMB data from ACT, SPT, and Planck, as well as Type Ia
supernova samples including Pantheon$^+$, DES-Dovekie, and Union3. We find that the GEDE model remains compatible with the $\Lambda$CDM paradigm, with no statistically significant preference for deviations when all
datasets are combined. In particular, the key model parameter $\Delta$ is consistent with the $\Lambda$CDM value $\Delta = 0$ within $2\sigma$ once SNe Ia data are included. Despite this overall agreement, the GEDE model does not exhibit the phantom crossing suggested by DESI DR2. Instead, the
evolution of the dark energy equation of state $w(z)$ indicates that the model behaves either as a full phantom ($w < -1$) or quintessence ($w > -1$), depending on the
dataset combination, without a clear transition across $w = -1$. When Pantheon$^+$ data are included, the model converges closely to $\Lambda$CDM with $w \simeq -1$. The GEDE model does not alleviate the existing cosmological tensions. The inferred values of $H_0$ remain in the range $67.9$-$69.8\ \mathrm{km,s^{-1},Mpc^{-1}}$, while the sound horizon $r_d$ and clustering parameter $S_8$ remain consistent with $\Lambda$CDM, failing to resolve the $H_0$ and $S_8$ tensions. Finally, both Gaussian significance levels ($<2\sigma$) and
Bayesian evidence ($\ln B_{i,j} < 1$) indicate no statistically significant preference for GEDE over $\Lambda$CDM. We conclude that, although DESI DR2 hints at dynamical dark energy, the GEDE model remains observationally indistinguishable from $\Lambda$CDM and does not support the Quintom-B-type behavior suggested by DESI DR2.
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All authors Vipin Kumar Sharma, Himanshu Chaudhary, Salvatore Capozziello, Dhruba Jyoti Gogoi, G. Mustafa
Fluid Dynamics
Foundations of a solved-volatility stochastic turbulence closure: Itô–Hencky kinematics, source-consistent momentum and finite-correlation realisation
Hsieh-Chen Tsai
Most
stochastic closures prescribe a covariance tensor, a noise basis or an eddy-viscosity field. This paper develops a different framework in which the displacement-
volatility field is solved together with the resolved velocity. The starting point is a one-channel Itô configuration map. A local
matrix-logarithm expansion gives distinct material and spatial Hencky increments, their quadratic-variation drifts and the exact pathwise volume constraint. Under constant density, one Brownian channel, pathwise isochoricity and no independent martingale in the resolved Eulerian drift, the material pull-back momentum equation is shown to be the on-shell form of the full
stochastic Reynolds transport balance when the momentum-source covariation is retained. The resulting velocity–
volatility–pressure system has an index-one differential–algebraic structure. Virtual power fixes the mechanical type of the stress impulse and separates work from quadratic covariation. A finite-correlation precursor then gives a Green–Kubo realisation of the solved displacement covariance. State dependence adds a Lyapunov noise-induced drift, while dynamic boundaries add reaction work and active/passive covariance compatibility conditions. The analysis also gives four limits: a non-zero Brownian transport limit cannot retain finite ordinary unresolved kinetic energy; total energy alone does not fix
entropy production; wall tangency limits covariance rank rather than the number of
stochastic modes; and a homogeneous decoupled Helmholtz–Stokes equation has only the trivial periodic solution. The result is a theory-complete, testable closure architecture. Developed turbulent statistics, logarithmic wall scaling and computational-fluid-dynamics validation are deliberately left to the expanded fluid-mechanics study.
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History and Philosophy of Physics
The Development of Detectors of High Energy Neutrinos and Cosmic Rays between 1980 and 2000
A A Watson
The construction of the DUMAND, Lake Baikal and IceCube detectors of high-energy
neutrinos are discussed, with some emphasis on the difficulties encountered. The decade from 1990 marked the period in which the Auger Observatory was conceived and the Collaboration evolved. Again, the difficulties that were overcome to create the Observatory are described. For both IceCube and the Auger Observatory, claims made in the 1980s for the observation of PeV gamma-rays from Cygnus X-3, played a not-insignificant role in their advance.
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Soft Condensed Matter
From real polymers to random graphs: percolation thresholds in associative polymer solutions
Xinxiang Chen, Lennart Hebestreit and Friederike Schmid
Sol-gel transitions are ubiquitous in soft matter and biological systems, yet their thresholds are often poorly captured by classical Flory-Stockmayer theory because spatial organization and loop formation are neglected. Here, we combine molecular dynamics simulations with random graph and random
geometric graph models to determine the respective roles of
topology and geometry in reversible associative
polymer solutions. We show that a coordinate-free random graph recovers the mean-field Flory-Stockmayer limit, whereas a random
geometric graph quantitatively reproduces the shifted percolation thresholds observed in molecular dynamics simulations when the detection radius is chosen according to the
polymer conformational size. This
geometric mapping remains quantitatively valid for linear chains with regularly spaced binding sites over a broad range of chain stiffness. At the microscopic level, we identify primary loops formed already in the pre-gel regime as the dominant source of the deviation from mean-field predictions. Near the gel point, the cluster-size statistics obtained from simulations and random
geometric graphs are consistent with the universality class of three-dimensional percolation. These results establish random
geometric graphs as a minimal predictive framework for describing topological transitions in reversible associative
polymer solutions and show that gelation and network formation can be inferred directly from single-chain conformational information.
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Optics
Geometry resolved atomic oxygen risk assessment for very low earth orbit spacecraft
Gun Hi Won, Hyun Jung Kim, SongYi Park et al. (+3 more)
Atomic oxygen (AO) is a major durability concern for spacecraft in very low Earth orbit (VLEO), yet orbit-averaged fluence does not resolve exposure on individual surfaces and internal components. This study develops a geometry-resolved AO assessment by coupling NRLMSISE-00, HWM07, and SYSTEMA ATOMOX. One-year simulations were performed for a 350 km circular Sun-synchronous orbit at LTAN 06:00 and 12:00 using a baseline spacecraft, a wedge-modified body, and two synthetic aperture radar
antenna sub-arrays. The LTAN 12:00 orbit produced 8-10% higher orbit-averaged AO flux than LTAN 06:00. For the baseline geometry, the ram-facing surface accumulated 6.9-7.5 x 10^21 atoms/cm^2, whereas side and zenith/nadir surfaces received only 3-5% of the ram fluence. Material-specific erosion yields changed the component-level risk ranking: the CFRP zenith panel was predicted to erode by 15.1-16.2 um/year despite receiving much lower fluence than the ram-facing multilayer insulation. The wedge generated approximately one order of magnitude spatial variation through local shielding. Housing openings also allowed AO to reach internal printed
circuit boards, with maximum annual fluences of 9.5 x 10^16 and 4.0 x 10^19 atoms/cm^2 in the H- and V-polarized
antenna models, respectively. HWM07 winds produced 10-20% side-panel asymmetry, which decreased below 1% when winds were disabled. Comparison with MISSE-8 reproduced the measured zenith-to-ram ratio of approximately 4% but underpredicted wake exposure, identifying a limitation of ballistic ray tracing. These results demonstrate that VLEO AO durability requires coupled consideration of orbit, atmospheric winds, geometry, and material response.
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All authors Gun Hi Won, Hyun Jung Kim, SongYi Park, ChangWon Seo, Eunji Lee, SeongSik Yoon
High Energy Physics (Phenomenology)
Pseudoscalar Yukawa Coupling Induced Helical Asymmetry in Fermionic Preheating
Ke FU, Li-Shuang Liu, Yu-Feng Wang et al. (+2 more)
In this study, we investigate the fermionic helical asymmetry during preheating by introducing a model in which the Dirac field $\psi$ couples to the scalar inflaton $\phi$ directly through the pseudoscalar Yukawa mechanism described by the term $- g\frac{\phi}{f} m_\psi \bar{\psi}\mathrm{i}\gamma^5 \psi$. Following inflation, as the inflaton oscillates around the minimum of its potential, the effective frequency of Dirac field changes non-adiabatically, resulting in particle production. These oscillations also indicate that the pseudo-mass $m_5 = g \phi m_\psi/f$ changes the sign, leading to the production of helical-asymmetric
fermions. We employ the WKB method to analytically calculate the transition relations of the Bogoliubov coefficients, which is valid for an arbitrary number of productions and demonstrates a significant difference compared to the case without asymmetry. In the expanding universe, the presence of pseudo-mass $m_5$ alters the Gaussian distributions for each helical state, since the combined effects of Pauli blocking and parametric resonance produce coherent enhancement and coherent suppression in certain frequency ranges. This departure arises from the imaginary component of the first-order adiabatic complex phase, denoted as $\Theta^{(r)}_{1}$. The real part of $\Theta^{(r)}_{1}$ significantly enhances the number density of each helical state after eight oscillations of the inflaton since the coherent superposition. These conclusions have also been validated by the numerical results.
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All authors Ke FU, Li-Shuang Liu, Yu-Feng Wang, Xin-Yu Gu, Xi-Bin Li
Atomic Physics
Experiments with interacting ultracold polar molecules
Philip D. Gregory, Jonathan M. Mortlock, Daniel K. Ruttley et al. (+1 more)
Ultracold polar molecules have emerged as an exciting platform for experiments in
quantum science, with many proposed applications seeking to leverage the existence of long-range dipolar interactions and the rich internal structure of long-lived states. However, the complexity of molecules also presents many experimental challenges. In this chapter, we review the experimental advances over the past two decades that have brought ultracold molecules under full
quantum control. We focus on three key topics: control of ultracold molecular collisions, engineering dipolar interactions and nascent
quantum simulations in optical
lattices.
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All authors Philip D. Gregory, Jonathan M. Mortlock, Daniel K. Ruttley, Simon L. Cornish
Astrophysics of Galaxies
Chemistry of Dark Molecular Clouds
Yuri Aikawa, Izaskun Jimenez-Serra and Paola Caselli
Recent molecular line surveys, particularly toward the starless core TMC-1 CP, have greatly expanded the inventory of interstellar molecules, revealing numerous isomers and even aromatic species. Their diverse formation pathways—from ion-molecule reactions to the possible fragmentation of carbonaceous grains—remain under debate, linking chemistry to the life cycle of the interstellar medium. Simple tracers such as carbon chains and deuterated ions are used to probe the physical conditions and evolutionary state of nearby filaments and cores, as well as in massive infrared dark clouds. Ice chemistry has also entered a new era with JWST: spatial distributions of ices indicate a connection between catastrophic freeze-out, established in the prestellar core L1544, and formation of complex organic molecules. Overall, TMC-1 CP and L1544 are not outliers but representative laboratories of molecular cloud physics and chemistry. Extending these findings across diverse environments, from the Central Molecular Zone to low-
metallicity galaxies, is essential for a unified picture of how interstellar chemistry regulates the path from clouds to
stars and
planets.
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General Relativity and Quantum Cosmology
Gravitational wave constraints on corrections to Bekenstein-Hawking Area Formula in classical F(R) gravity and quantum GR : implications for theory parameters
Parthasarathi Majumdar
This contribution considers constraints from analyses of gravitational wave data from binary black hole coalescence, on possible corrections to the Bekenstein-Hawking Area Formula for black hole
entropy. Most recent analyses of gravitational wave data from the LVK Consortium appear to confirm the Hawking Area
Theorem for black holes at a $5 \sigma$ accuracy, for the `loudest' signal (SNR of the order of $80$) of binary black hole merger inherent in the recent observation GW250114. Amalgamating this result with Bekenstein's ideas of black hole
entropy and the generalized second law of thermodynamics, we constrain leading inverse area corrections for large horizon area spherical black hole solutions of classical $F(R)$
gravity, using the Wald
entropy function formalism. The implementation of the observational constraints entails the notion of `absolute consistency' which we introduce and contrast with `relative consistency'. This absolute consistency criterion is shown to relate some of the parameters of $F(R)$
gravity. Next we consider leading
quantum general relativistic corrections to the Area formula, arising both from the non-perturbative matter-free Loop
Quantum Gravity and matter-dependent, perturbative
Entanglement entropy approaches. Combining the leading logarithmic corrections in horizon area (for large areas) from both approaches, and imposing absolute consistency with the observational validation of the Area
Theorem, is shown to lead to significant restrictions on the
spin and number of species of Beyond Standard Model spectrum of elementary particles, some of which are often assumed to be Dark Matter candidates.
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Mesoscale and Nanoscale Physics
Tip-Tuned Renormalization-Group Spectroscopy Unmasks a False-positive Topological Superconducting Vortex
Zhenhua Zhu, Qun Zhu, Yong-Wei Wang et al. (+6 more)
Clean, nonsplit
vortex zero-bias peaks (ZBPs) can be misinterpreted as Majorana zero modes (MZMs), making static scanning tunneling microscopy intrinsically ambiguous. Here we use the STM tip coupling to drive a local boundary-renormalization-group (boundary RG) flow, turning dynamical Coulomb blockade into a falsification test for Majorana-like ZBPs. Experimentally, in a $\mathrm{SrSn}_3$ thin film, normal-state spectra establish an Ohmic dissipative environment, and a common boundary-RG/thermodynamic-Bethe-ansatz analysis of the superconducting-gap and
vortex-center spectra yields consistent dissipation strengths within the $r < 1/2$ Majorana-filter regime. Lowering the tip nevertheless drives a clean, non-split
vortex-center ZBP into a zero-bias dip, opposite to the protected flow of an isolated MZM, unmasking the peak as a Majorana false positive produced by a conventional
vortex-core state. The same flow selectively suppresses the strongly tip-coupled channel, resolving the two-gap superconductivity. Dissipative STM thus tests dynamical protection rather than spectral appearance.
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All authors Zhenhua Zhu, Qun Zhu, Yong-Wei Wang, Gu Zhang, Jihai Zhang, Xu-Cun Ma, Qi-Kun Xue, Can-Li Song, Dong E. Liu
Solar and Stellar Astrophysics
Decay Length of Slow Magnetoacoustic Waves in the Solar Corona using SDO/AIA and SolO/EUI
R. L. Meadowcroft, N. Narang, D. Berghmans et al. (+2 more)
Slow magnetoacoustic waves have been observed in the
solar corona for decades; yet, existing theories do not fully explain the wide range of observed decay lengths, and measurements from different instruments frequently disagree. We present two events with simultaneous SDO/AIA and
Solar Orbiter/EUI-HRIEUV observations of slow waves in sunspot-anchored coronal fan feathers. In Event 1, the LoS are separated by 16.2 degrees, while in Event 2, they are almost parallel. Using time-distance analysis, we identify waves with periods in the 3-minute band and quantify wave decay using the exponential folding length. When LoS are non-parallel, the ratio of decay lengths measured by the two instruments, $\lambda_\mathrm{ratio} = \lambda_{\mathrm{AIA}} / \lambda_{\mathrm{EUI}}$ varies widely, with both $\lambda_\mathrm{ratio} > 1$ and $\lambda_\mathrm{ratio} < 1$ observed. However, when the LoS are almost parallel, the decay lengths agree with one another, and $\lambda_\mathrm{ratio} \approx 1$. These results show that the angle between the LoS and the wave propagation direction is key to determining the apparent decay of slow waves, a factor that has not yet been systematically accounted for. Since statistical studies of decay lengths constrain coronal energy-loss mechanisms, observational effects beyond simple projection must be corrected to reliably infer the underlying physical dissipation processes.
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All authors R. L. Meadowcroft, N. Narang, D. Berghmans, M. Dominique, V. M. Nakariakov
Quantum Gases
From weakly to strongly-interacting driven-dissipative bosons in one dimension
Martina Zündel, Loïc Herviou, Léonie Canet et al. (+1 more)
We consider a one-dimensional driven-dissipative Bose-Hubbard model subjected to incoherent pump and one- and two-body losses, and analyze it by studying its two-point space-time correlations. By employing a combination of numerical methods, such as
stochastic semi-classical simulations and tensor network methods, as well as perturbation theory within the Keldysh formalism, we characterize the system at varying filling and interaction strength. We present results for two complementary regimes: i) at large filling and weak interactions, where we show that Kardar-Parisi-Zhang scaling is visible in the linewidth of the spectral function and ii) at weak filling and strong interactions, where we analyze what remains of the mean field transition and identify a change of nature of the excitations. Our study covers two important regions of the phase diagram of such a system.
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All authors Martina Zündel, Loïc Herviou, Léonie Canet, Anna Minguzzi
Soft Condensed Matter
Ultra-broadband and time-resolved depolarized dynamic light scattering for probing molecular dynamics in supercooled liquids and glasses
Till Böhmer, Rolf Zeißler, Robin Schwäch et al. (+3 more)
Dynamic light scattering (DLS) is a versatile technique for probing microscopic dynamics in soft condensed matter. However, applying DLS to supercooled molecular
liquids and glasses demands exceptional experimental performance due to weak depolarized scattering, slow relaxation near the glass transition, and the need for quantitative comparison with complementary spectroscopic techniques. In this tutorial we discuss, how a depolarized dynamic light scattering (DDLS) setup can be tailored to meet these challenges. By combining conventional fiber-optical
photon correlation spectroscopy, and multispeckle
photon correlation imaging with high-frequency DDLS, such a setup allows to capture rotational dynamics across more than 20 orders of magnitude in time. We detail the experimental design required for high signal-to-noise ratios and long-term optical stability, alongside the treatment of coherence and partial heterodyning effects. As we demonstrate, after proper treatment the different detection schemes yield the same electric-field autocorrelation function, enabling the construction of continuous, ultra-broadband DDLS
datasets. Furthermore, multispeckle detection enables time-resolved correlation measurements without temporal averaging, extending DDLS to non-
equilibrium systems such as aging molecular glasses. This methodology establishes a unified experimental framework for quantitative investigations of
equilibrium and non-
equilibrium molecular reorientation dynamics over an exceptionally broad time range.
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All authors Till Böhmer, Rolf Zeißler, Robin Schwäch, Jan P. Gabriel, Florian Pabst, Thomas Blochowicz