TY - JOUR A1 - Perottoni, Hélio D. A1 - Limberg, Guilherme A1 - Amarante, João A. S. A1 - Rossi, Silvia A1 - Queiroz, Anna B. A. A1 - Santucci, Rafael M. A1 - Pérez-Villegas, Angeles A1 - Chiappini, Cristina T1 - The unmixed debris of Gaia-Sausage/Enceladus in the form of a pair of halo stellar overdensities JF - Astrophysical journal letters N2 - In the first billion years after its formation, the galaxy underwent several mergers with dwarf satellites of various masses. The debris of Gaia-Sausage/Enceladus (GSE), the galaxy responsible for the last significant merger of the Milky Way, dominates the inner halo and has been suggested to be the progenitor of both the Hercules-Aquila Cloud (HAC) and Virgo Overdensity (VOD). We combine SEGUE, APOGEE, Gaia, and StarHorse distances to characterize the chemodynamical properties and verify the link between HAC, VOD, and GSE. We find that the orbital eccentricity distributions of the stellar overdensities and GSE are comparable. We also find that they have similar, strongly peaked, metallicity distribution functions, reinforcing the hypothesis of common origin. Furthermore, we show that HAC and VOD are indistinguishable from the prototypical GSE population within all chemical-abundance spaces analyzed. All these evidences combined provide a clear demonstration that the GSE merger is the main progenitor of the stellar populations found within these halo overdensities. Y1 - 2022 U6 - https://doi.org/10.3847/2041-8213/ac88d6 SN - 2041-8205 SN - 2041-8213 VL - 936 IS - 1 PB - IOP Publishing CY - Bristol ER - TY - JOUR A1 - Pranav, Manasi A1 - Hultzsch, Thomas A1 - Musiienko, Artem A1 - Sun, Bowen A1 - Shukla, Atul A1 - Jaiser, Frank A1 - Shoaee, Safa A1 - Neher, Dieter T1 - Anticorrelated photoluminescence and free charge generation proves field-assisted exciton dissociation in low-offset PM6:Y5 organic solar cells JF - APL materials : high impact open access journal in functional materials science N2 - Understanding the origin of inefficient photocurrent generation in organic solar cells with low energy offset remains key to realizing high-performance donor-acceptor systems. Here, we probe the origin of field-dependent free-charge generation and photoluminescence in wnon-fullereneacceptor (NFA)-based organic solar cells using the polymer PM6 and the NFA Y5-a non-halogenated sibling to Y6, with a smaller energetic offset to PM6. By performing time-delayed collection field (TDCF) measurements on a variety of samples with different electron transport layers and active layer thickness, we show that the fill factor and photocurrent are limited by field-dependent free charge generation in the bulk of the blend. We also introduce a new method of TDCF called m-TDCF to prove the absence of artifacts from non-geminate recombination of photogenerated and dark charge carriers near the electrodes. We then correlate free charge generation with steady-state photoluminescence intensity and find perfect anticorrelation between these two properties. Through this, we conclude that photocurrent generation in this low-offset system is entirely controlled by the field-dependent dissociation of local excitons into charge-transfer states. (c) 2023 Author(s). Y1 - 2023 U6 - https://doi.org/10.1063/5.0151580 SN - 2166-532X VL - 11 IS - 6 PB - AIP Publishing CY - Melville ER - TY - JOUR A1 - Stojkoski, Viktor A1 - Jolakoski, Petar A1 - Pal, Arnab A1 - Sandev, Trifce A1 - Kocarev, Ljupco A1 - Metzler, Ralf T1 - Income inequality and mobility in geometric Brownian motion with stochastic resetting: theoretical results and empirical evidence of non-ergodicity JF - Philosophical transactions of the Royal Society A: Mathematical, physical and engineering sciences N2 - We explore the role of non-ergodicity in the relationship between income inequality, the extent of concentration in the income distribution, and income mobility, the feasibility of an individual to change their position in the income rankings. For this purpose, we use the properties of an established model for income growth that includes 'resetting' as a stabilizing force to ensure stationary dynamics. We find that the dynamics of inequality is regime-dependent: it may range from a strictly non-ergodic state where this phenomenon has an increasing trend, up to a stable regime where inequality is steady and the system efficiently mimics ergodicity. Mobility measures, conversely, are always stable over time, but suggest that economies become less mobile in non-ergodic regimes. By fitting the model to empirical data for the income share of the top earners in the USA, we provide evidence that the income dynamics in this country is consistently in a regime in which non-ergodicity characterizes inequality and immobility. Our results can serve as a simple rationale for the observed real-world income dynamics and as such aid in addressing non-ergodicity in various empirical settings across the globe.This article is part of the theme issue 'Kinetic exchange models of societies and economies'. KW - income inequality KW - income mobility KW - geometric Brownian motion KW - non-ergodicity KW - stochastic resetting Y1 - 2022 U6 - https://doi.org/10.1098/rsta.2021.0157 SN - 1364-503X SN - 1471-2962 VL - 380 IS - 2224 PB - Royal Society CY - London ER - TY - JOUR A1 - Mayer, Dennis A1 - Lever, Fabiano A1 - Picconi, David A1 - Metje, Jan A1 - Ališauskas, Skirmantas A1 - Calegari, Francesca A1 - Düsterer, Stefan A1 - Ehlert, Christopher A1 - Feifel, Raimund A1 - Niebuhr, Mario A1 - Manschwetus, Bastian A1 - Kuhlmann, Marion A1 - Mazza, Tommaso A1 - Robinson, Matthew Scott A1 - Squibb, Richard J. A1 - Trabattoni, Andrea A1 - Wallner, Måns A1 - Saalfrank, Peter A1 - Wolf, Thomas J. A. A1 - Gühr, Markus T1 - Following excited-state chemical shifts in molecular ultrafast x-ray photoelectron spectroscopy JF - Nature communications N2 - Imaging the charge flow in photoexcited molecules would provide key information on photophysical and photochemical processes. Here the authors demonstrate tracking in real time after photoexcitation the change in charge density at a specific site of 2-thiouracil using time-resolved X-ray photoelectron spectroscopy. The conversion of photon energy into other energetic forms in molecules is accompanied by charge moving on ultrafast timescales. We directly observe the charge motion at a specific site in an electronically excited molecule using time-resolved x-ray photoelectron spectroscopy (TR-XPS). We extend the concept of static chemical shift from conventional XPS by the excited-state chemical shift (ESCS), which is connected to the charge in the framework of a potential model. This allows us to invert TR-XPS spectra to the dynamic charge at a specific atom. We demonstrate the power of TR-XPS by using sulphur 2p-core-electron-emission probing to study the UV-excited dynamics of 2-thiouracil. The method allows us to discover that a major part of the population relaxes to the molecular ground state within 220-250 fs. In addition, a 250-fs oscillation, visible in the kinetic energy of the TR-XPS, reveals a coherent exchange of population among electronic states. Y1 - 2022 U6 - https://doi.org/10.1038/s41467-021-27908-y SN - 2041-1723 N1 - Publisher correction: https://doi.org/10.1038/s41467-022-28584-2 VL - 13 IS - 1 PB - Nature Research CY - Berlin ER - TY - JOUR A1 - Liu, Ji-Cai A1 - Ignatova, Nina A1 - Kimberg, Victor A1 - Krasnov, Pavel A1 - Föhlisch, Alexander A1 - Simon, Marc A1 - Gel'mukhanov, Faris T1 - Time-resolved study of recoil-induced rotation by X-ray pump - X-ray probe spectroscopy JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - Modern stationary X-ray spectroscopy is unable to resolve rotational structure. In the present paper, we propose to use time-resolved two color X-ray pump-probe spectroscopy with picosecond resolution for real-time monitoring of the rotational dynamics induced by the recoil effect. The proposed technique consists of two steps. The first short pump X-ray pulse ionizes the valence electron, which transfers angular momentum to the molecule. The second time-delayed short probe X-ray pulse resonantly excites a 1s electron to the created valence hole. Due to the recoil-induced angular momentum the molecule rotates and changes the orientation of transition dipole moment of core-excitation with respect to the transition dipole moment of the valence ionization, which results in a temporal modulation of the probe X-ray absorption as a function of the delay time between the pulses. We developed an accurate theory of the X-ray pump-probe spectroscopy of the recoil-induced rotation and study how the energy of the photoelectron and thermal dephasing affect the structure of the time-dependent X-ray absorption using the CO molecule as a case-study. We also discuss the feasibility of experimental observation of our theoretical findings, opening new perspectives in studies of molecular rotational dynamics. Y1 - 2022 U6 - https://doi.org/10.1039/d1cp05000a SN - 1463-9076 SN - 1463-9084 VL - 24 IS - 11 SP - 6627 EP - 6638 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Abiuso, Paolo A1 - Holubec, Viktor A1 - Anders, Janet A1 - Ye, Zhuolin A1 - Cerisola, Federico A1 - Perarnau-Llobet, Marti T1 - Thermodynamics and optimal protocols of multidimensional quadratic Brownian systems JF - Journal of physics communications N2 - We characterize finite-time thermodynamic processes of multidimensional quadratic overdamped systems. Analytic expressions are provided for heat, work, and dissipation for any evolution of the system covariance matrix. The Bures-Wasserstein metric between covariance matrices naturally emerges as the local quantifier of dissipation. General principles of how to apply these geometric tools to identify optimal protocols are discussed. Focusing on the relevant slow-driving limit, we show how these results can be used to analyze cases in which the experimental control over the system is partial. KW - stochastic thermodynamics KW - thermodynamic control KW - thermodynamic length KW - overdamped brownian systems Y1 - 2022 U6 - https://doi.org/10.1088/2399-6528/ac72f8 SN - 2399-6528 VL - 6 IS - 6 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Voroshnin, Vladimir A1 - Tarasov, Artem V. A1 - Bokai, Kirill A. A1 - Chikina, Alla A1 - Senkovskiy, Boris V. A1 - Ehlen, Niels A1 - Usachov, Dmitry Yu. A1 - Gruneis, Alexander A1 - Krivenkov, Maxim A1 - Sanchez-Barriga, Jaime A1 - Fedorov, Alexander T1 - Direct spectroscopic evidence of magnetic proximity effect in MoS2 monolayer on graphene/Co JF - ACS nano N2 - A magnetic field modifies optical properties and provides valley splitting in a molybdenum disulfide (MoS2) monolayer. Here we demonstrate a scalable approach to the epitaxial synthesis of MoS2 monolayer on a magnetic graphene/Co system. Using spin- and angle-resolved photoemission spectroscopy we observe a magnetic proximity effect that causes a 20 meV spin-splitting at the (Gamma) over bar point and canting of spins at the (K) over bar point in the valence band toward the in-plane direction of cobalt magnetization. Our density functional theory calculations reveal that the in-plane spin component at (K) over bar is localized on Co atoms in the valence band, while in the conduction band it is localized on the MoS2 layer. The calculations also predict a 16 meV spin-splitting at the (Gamma) over bar point and 8 meV (K) over bar-(K) over bar' valley asymmetry for an out-of-plane magnetization. These findings suggest control over optical transitions in MoS2 via Co magnetization. Our estimations show that the magnetic proximity effect is equivalent to the action of the magnetic field as large as 100 T. KW - magnetic proximity effect KW - MoS2 KW - monolayer KW - graphene KW - spin-resolved KW - ARPES Y1 - 2022 U6 - https://doi.org/10.1021/acsnano.1c10391 SN - 1936-0851 SN - 1936-086X VL - 16 IS - 5 SP - 7448 EP - 7456 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Miller, Amy E. A1 - Cioni, Maria-Rosa L. A1 - de Grijs, Richard A1 - Sun, Ning-Chen A1 - Bell, Cameron P. M. A1 - Choudhury, Samyaday A1 - Ivanov, Valentin D. A1 - Marconi, Marcella A1 - Oliveira, Joana M. A1 - Petr-Gotzens, Monika A1 - Ripepi, Vincenzo A1 - van Loon, Jacco Th. T1 - The VMC survey - XLVII. Turbulence-controlled hierarchical star formation in the large magellanic cloud JF - Monthly notices of the Royal Astronomical Society N2 - We perform a statistical clustering analysis of upper main-sequence stars in the Large Magellanic Cloud (LMC) using data from the Visible and Infrared Survey Telescope for Astronomy survey of the Magellanic Clouds. We map over 2500 young stellar structures at 15 significance levels across similar to 120 square degrees centred on the LMC. The structures have sizes ranging from a few parsecs to over 1 kpc. We find that the young structures follow power-law size and mass distributions. From the perimeter-area relation, we derive a perimeter-area dimension of 1.44 +/- 0.20. From the mass-size relation and the size distribution, we derive two-dimensional fractal dimensions of 1.50 +/- 0.10 and 1.61 +/- 0.20, respectively. We find that the surface density distribution is well represented by a lognormal distribution. We apply the Larson relation to estimate the velocity dispersions and crossing times of these structures. Our results indicate that the fractal nature of the young stellar structures has been inherited from the gas clouds from which they form and that this architecture is generated by supersonic turbulence. Our results also suggest that star formation in the LMC is scale-free from 10 to 700 pc. KW - methods: statistical KW - stars: early-type KW - stars: formation KW - galaxies: individual: Magellanic Clouds KW - galaxies: stellar content KW - galaxies: structure Y1 - 2022 U6 - https://doi.org/10.1093/mnras/stac508 SN - 0035-8711 SN - 1365-2966 VL - 512 IS - 1 SP - 1196 EP - 1213 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Griggio, Massimo A1 - Bedin, Luigi R. A1 - Raddi, Roberto A1 - Reindl, Nicole A1 - Tomasella, Lina A1 - Scalco, M. A1 - Salaris, M. A1 - Cassisi, S. A1 - Ochner, P. A1 - Ciroi, S. A1 - Rosati, P. A1 - Nardiello, Domenico A1 - Anderson, J. A1 - Libralato, Mattia A1 - Bellini, A. A1 - Vallenari, A. A1 - Spina, L. A1 - Pedani, M. T1 - Astro-photometric study of M37 with Gaia and wide-field ugi-imaging JF - Monthly notices of the Royal Astronomical Society N2 - We present an astrometric and photometric wide-field study of the Galactic open star cluster M37 (NGC 2099). The studied field was observed with ground-based images covering a region of about four square degrees in the Sloan-like filters ugi. We exploited the Gaia catalogue to calibrate the geometric distortion of the large field mosaics, developing software routines that can be also applied to other wide-field instruments. The data are used to identify the hottest white dwarf (WD) member candidates of M37. Thanks to the Gaia EDR3 exquisite astrometry we identified seven such WD candidates, one of which, besides being a high-probability astrometric member, is the putative central star of a planetary nebula. To our knowledge, this is a unique object in an open cluster, and we have obtained follow-up low-resolution spectra that are used for a qualitative characterization of this young WD. Finally, we publicly release a three-colour atlas and a catalogue of the sources in the field of view, which represents a complement of existing material. KW - catalogues KW - white dwarfs KW - open clusters and associations: individual: KW - M37 (NGC2099) Y1 - 2022 U6 - https://doi.org/10.1093/mnras/stac1920 SN - 0035-8711 SN - 1365-2966 VL - 515 IS - 2 SP - 1841 EP - 1853 PB - Oxford University Press CY - Oxford ER - TY - JOUR A1 - Pelisoli, Ingrid A1 - Dorsch, Matti A1 - Heber, Ulrich A1 - Gänsicke, Boris A1 - Geier, Stephan A1 - Kupfer, Thomas A1 - Nemeth, Peter A1 - Scaringi, Simone A1 - Schaffenroth, Veronika T1 - Discovery and analysis of three magnetic hot subdwarf stars BT - evidence for merger-induced magnetic fields JF - Monthly notices of the Royal Astronomical Society N2 - Magnetic fields can play an important role in stellar evolution. Among white dwarfs, the most common stellar remnant, the fraction of magnetic systems is more than 20 per cent. The origin of magnetic fields in white dwarfs, which show strengths ranging from 40 kG to hundreds of MG, is still a topic of debate. In contrast, only one magnetic hot subdwarf star has been identified out of thousands of known systems. Hot subdwarfs are formed from binary interaction, a process often associated with the generation of magnetic fields, and will evolve to become white dwarfs, which makes the lack of detected magnetic hot subdwarfs a puzzling phenomenon. Here we report the discovery of three new magnetic hot subdwarfs with field strengths in the range 300-500 kG. Like the only previously known system, they are all helium-rich O-type stars (He-sdOs). We analysed multiple archival spectra of the three systems and derived their stellar properties. We find that they all lack radial velocity variability, suggesting formation via a merger channel. However, we derive higher than typical hydrogen abundances for their spectral type, which are in disagreement with current model predictions. Our findings suggest a lower limit to the magnetic fraction of hot subdwarfs of 0.147(+0.143)(-0.047) per cent, and provide evidence for merger-induced magnetic fields which could explain white dwarfs with field strengths of 50-150 MG, assuming magnetic flux conservation. KW - stars: magnetic field KW - subdwarfs Y1 - 2022 U6 - https://doi.org/10.1093/mnras/stac1069 SN - 0035-8711 SN - 1365-2966 VL - 515 IS - 2 SP - 2496 EP - 2510 PB - Oxford University Press CY - Oxford ER -