Search

The quality of numerical computations can be measured through their forward error, for which finding good error bounds is challenging in general. For several algorithms and using stochastic rounding (SR), probabilistic analysis has been shown to be an effective alternative for obtaining tight error bounds. This analysis considers the distribution of errors and evaluates the algorithm's performance on average. Using martingales and the Azuma-Hoeffding inequality, it provides error bounds that are valid with a certain probability and in $\mathcal{O}(\sqrt{n}u)$ instead of deterministic worst-case bounds in $\mathcal{O}(nu)$, where $n$ is the number of operations and $u$ is the unit roundoff.In this paper, we present a general method that automatically constructs a martingale for any computation scheme with multi-linear errors based on additions, subtractions, and multiplications. We apply this generalization to algorithms previously studied with SR, such as pairwise summation and the Horner algorithm, and prove equivalent results. We also analyze a previously unstudied algorithm, Karatsuba polynomial multiplication, which illustrates that the method can handle reused intermediate computations.

We report the discovery of a super-Earth candidate orbiting the nearby mid M dwarf Gl\,725A using the radial velocity (RV) method. The planetary signal has been independently identified using high-precision RVs from the SOPHIE and SPIRou spectrographs, in the optical and near-infrared domains, respectively. We modelled the stellar activity signal jointly with the planet using two Gaussian Processes, one for each instrument to account for the chromaticity of the stellar activity and instrumental systematics, along with a Keplerian model. The signal is significantly detected with a RV semi-amplitude of $1.67\pm0.20$ m/s. The planet Gl 725A b is found to be in an orbit compatible with circular with a period of $11.2201\pm0.0051$ days. We analysed 27 sectors of TESS photometry on which no transit event was found. We determined a minimum mass of $M_{p}\sin{i}=2.78\pm0.35\,M_{\oplus}$ which places the planet in the super-Earth regime. Using Mass-Radius relationships we predict a planetary radius to be between 1.2 and $2.0\,R_{\oplus}$. The proximity of Gl 725A, of only 3.5 pc, makes this new exoplanet one of the closest to Earth and joins the group of S-type low-mass planets in short orbits ($P<15$ d) around close M dwarfs., Comment: 26 pages, 17 figures. Accepted in A&A

We report the results of a comprehensive study of the spectroscopic binary (SB2) system HD 34736 hosting two chemically peculiar (CP) late B-type stars. Using new and archival observational data, we characterise the system and its components, including their rotation and magnetic fields. Fitting of the radial velocities yields $P_\mathrm{orb}=83.\!^\mathrm{d}219(3)$ and $e=0.8103(3)$. The primary component is a CP He-wk star with $T_{\mathrm{eff}A}=13000\pm500$ K and $\upsilon_\mathrm{e}\sin i\;=75\pm3$ km/s, while the secondary exhibits variability of Mg and Si lines, and has $T_{\mathrm{eff}B}=11500\pm1000$ K and $\upsilon_\mathrm{e}\sin i=110$-180 km/s. TESS and KELT photometry reveal clear variability of the primary component with a rotational period $P_{\mathrm{rot}A}=1.\!^\mathrm{d}279\,988\,5(11)$, which is lengthening at a rate of $1.26(6)$ s/yr. For the secondary, $P_{\mathrm{rot}B}=0.\!^\mathrm{d}522\,693\,8(5)$, reducing at a rate of $-0.14(3)$ s/yr. The longitudinal component $\langle B_\mathrm{z}\rangle$ of the primary's strongly asymmetric global magnetic field varies from $-6$ to +5 kG. Weak spectropolarimetric evidence of a magnetic field is found for the secondary star. The observed X-ray and radio emission of HD 34736 may equally be linked to a suspected T Tau-like companion or magnetospheric emission from the principal components. Given the presence of a possible third magnetically active body, one can propose that the magnetic characteristics of the protostellar environment may be connected to the formation of such systems., Comment: This preprint has 28 pages, 23 figures, and includes the complete version of Table 1. Published in MNRAS

Jammed structures with finite shear modulus emerge from polycrystalline monodisperse and disordered bidisperse granular packings. To link these macroscopic mechanical properties with microstructural characteristics, we examine the vibrational behavior of two-dimensional polycrystalline monodisperse and disordered bidisperse systems using discrete element method simulations. The vibrational density of states (DOS) reflects structural disorder and soft modes, and we analyze this for both types of packings as they approach jamming and unjamming densities. Our results reveal that the low-frequency plateau in the DOS, observed in both polycrystalline and disordered packings, originates from nonaffine particle displacements, particularly those involving "rattlers", which are prominent near jamming and unjamming states. Although the jamming and unjamming process is irreversible, we find no evidence of expected history dependence in the DOS across any of the systems studied., Comment: 6 pages, 4 figures

We consider an outward degenerate drifted Brownian motion in the quarter plane with oblique reflections on the boundaries. In this article, we explicitly compute the Laplace transforms of the Green's functions associated with the process. These Laplace transforms are expressed as an infinite sum of products using the compensation method. We also derive the asymptotics of the Green's functions along all possible paths and determine the (minimal) Martin boundary. Finally, we provide explicit formulae for all the corresponding harmonic functions.

We present the results of Phase I of an ongoing review of Monte Carlo tools relevant for low-energy hadronic cross sections. This includes a detailed comparison of Monte Carlo codes for electron-positron scattering into a muon pair, pion pair, and electron pair, for scan and radiative-return experiments. After discussing the various approaches that are used and effects that are included, we show differential cross sections obtained with AfkQed, BabaYaga@NLO, KKMC, MCGPJ, McMule, Phokhara, and Sherpa, for scenarios that are inspired by experiments providing input for the dispersive evaluation of the hadronic vacuum polarisation., Comment: RadioMonteCarLow 2 Working Group report Phase I, 67 pages, 34 figures

Context: Transmission spectroscopy is a powerful tool for understanding exoplanet atmospheres. At optical wavelengths, it makes it possible to infer the composition and the presence of aerosols in the atmosphere. However, unocculted stellar activity can result in contamination of atmospheric transmission spectra by introducing spurious slopes and molecular signals. Aims: We aim to characterise the atmosphere of the transiting exoplanet WASP-69b, a hot Jupiter orbiting an active K star, and characterise the host star's activity levels. Methods: We obtained three nights of spectrophotometric data with the FORS2 instrument on the VLT, covering a wavelength range of 340-1100 nm. We performed retrievals on the full spectrum with combined stellar activity and planet atmosphere models. Results: We directly detect a facula in the form of a hot spot crossing event in one of the transits and indirectly detect unocculted faculae through an apparently decreasing radius towards the blue end of the transmission spectrum. We determine a facula temperature of $\Delta T=+644^{+427}_{-263}$ K for the former and a stellar coverage fraction of around 30% with a temperature of $\Delta T=+231\pm72$ K for the latter. The planetary atmosphere is best fit with a high-altitude cloud deck at 1.4 mbar that mutes atomic and molecular features. We find indications of water and ammonia with $log(H_2O)=-2.01^{+0.54}_{-0.86}$ and $log(NH_3)=-3.4^{+0.96}_{-5.20} respectively and place 3$\sigma$ upper limits on TiO ($10^{-7.65}$) and K ($10^{-7}$). Conclusions. The simultaneous multi-wavelength observations allow us to break the size-contrast degeneracy for facula-crossings, meaning we can obtain temperatures for both the directly and indirectly detected faculae, which are consistent with each other., Comment: Accepted in A\&A, 18 pages, 10 figures

In this work, we present conception and study of gallium nitride (GaN) nanostructures on a gallium arsenide (GaAs) substrate with (111)A orientation. The nanostructures were designed by GaN droplet epitaxy and studied in-situ by X-ray photoelectron spectroscopy and ex-situ by atomic force microscopy, scanning electron microscopy and transmission electron microscopy. These studies were coupled with kinetic Monte Carlo simulations to precisely understand the phenomena occurring during the nitridation and to find the optimum conditions for complete nitridation of gallium droplets. The HRTEM observation showed a cubic (zinc blende) crystal structure of the GaN nanodots for a nitridation at 300{\deg}C. Ramping the temperature from 100{\deg}C to 350{\deg}C during droplet nitridation enabled to obtain a very high density (>1011cm-2) of GaN nanodots with the zinc blende crystallinity.

EK Draconis, a nearby young solar-type star (G1.5V, 50-120 Myr), is known as one of the best proxies for inferring the environmental conditions of the young Sun. The star frequently produces superflares and Paper I presented the first evidence of an associated gigantic prominence eruption observed as a blueshifted H$\alpha$ Balmer line emission. In this paper, we present the results of dynamical modeling of the stellar eruption and examine its relationship to the surface starspots and large-scale magnetic fields observed concurrently with the event. By performing a one-dimensional free-fall dynamical model and a one dimensional hydrodynamic simulation of the flow along the expanding magnetic loop, we found that the prominence eruption likely occurred near the stellar limb (12$^{+5}_{-5}$-16$^{+7}_{-7}$ degrees from the limb) and was ejected at an angle of 15$^{+6}_{-5}$-24$^{+6}_{-6}$ degrees relative to the line of sight, and the magnetic structures can expand into a coronal mass ejection (CME). The observed prominence displayed a terminal velocity of $\sim$0 km s$^{-1}$ prior to disappearance, complicating the interpretation of its dynamics in Paper I. The models in this paper suggest that prominence's H$\alpha$ intensity diminishes at around or before its expected maximum height, explaining the puzzling time evolution in observations. The TESS light curve modeling and (Zeeman) Doppler Imaging revealed large mid-latitude spots with polarity inversion lines and one polar spot with dominant single polarity, all near the stellar limb during the eruption. This suggests that mid-latitude spots could be the source of the pre-existing gigantic prominence we reported in Paper I. These results provide valuable insights into the dynamic processes that likely influenced the environments of early Earth, Mars, Venus, and young exoplanets., Comment: 25 pages, 14 figures, 5 tables. Accepted for publication in The Astrophysical Journal

The response of a graphene Hall-Effect sensor to the inhomogeneous magnetic field generated by a dipole located above it, is investigated numerically at room temperature as a function of the dipole position, its orientation and the conduction regime of the sensor, i.e., diffusive or ballistic. By means of dedicated models, we highlight that the correction factor {\alpha} frequently used to relate the Hall voltage to the magnetic field averaged over the sensor area can be greatly improved in the high proximity situation enabled by the use of graphene, particularly in the ballistic regime. In addition, it is demonstrated that by fine-tuning the dipole position in the sensor plane, the Hall response becomes highly selective with respect to the dipole orientation. These analyses show that diffusive graphene Hall sensors may be preferred for particle detection, while ballistic ones used as close as possible to a nanomagnet would be preferred for magnetometry. With the support of micromagnetic simulations, the principle of the magnetic hysteresis loop measurement of an isolated nanomagnet is quantitively demonstrated with large signal-to-noise ratio to probe incoherent magnetization reversal. Devices based on specially designed graphene Hall crosses operating in the ballistic regime promise to outperform state-of-the-art ballistic Hall sensors based on semiconductor quantum wells especially for nano-magnetometry.

Autonomous robots navigating in off-road terrain like forests open new opportunities for automation. While off-road navigation has been studied, existing work often relies on clearly delineated pathways. We present a method allowing for long-range planning, exploration and low-level control in unknown off-trail forest terrain, using vision and GPS only. We represent outdoor terrain with a topological map, which is a set of panoramic snapshots connected with edges containing traversability information. A novel traversability analysis method is demonstrated, predicting the existence of a safe path towards a target in an image. Navigating between nodes is done using goal-conditioned behavior cloning, leveraging the power of a pretrained vision transformer. An exploration planner is presented, efficiently covering an unknown off-road area with unknown traversability using a frontiers-based approach. The approach is successfully deployed to autonomously explore two 400 meters squared forest sites unseen during training, in difficult conditions for navigation.

Particle accelerators with superconducting magnets operating at cryogenic temperatures use a beam screen (BS) liner that extracts heat generated by the circulating bunched charge particle beam before it can reach the magnets. The BS surface, commonly made of high-conductivity copper, provides a low impedance for beam stability reasons, low secondary electron yield (SEY)to mitigate the electron-cloud (EC) effect, and low electron-stimulated desorption yield (ESD) to limit the dynamic pressure rise due to EC. Rare-earth barium copper oxide (REBCO) high-temperature superconductors (HTs) recently reached technical maturity, are produced as coated conductor tapes (REBCO-CCs), and will be considered for application in future colliders to decrease the BS impedance and enable operation at around 50 K, consequently relaxing the cryogenic requirements. Aside from HTS properties, industry-grade REBCO-CCs also need qualification for EC and dynamic vacuum compatibility under accelerator-like conditions. Hence, we report the SEY and ESD measured at cryogenic temperatures of 12 K under low-energy electron irradiation of 0 - 1.4 keV. We also verify the sample compositions and morphologies using XPS, SEM, and EDS methods. The energy and dose dependencies of ESD are comparable to those of technical-grade metals and one sample reached SEY$_{MAX}=$1.2 after electron conditioning.

Dense cold molecular cores/filaments are surrounded by an envelope of translucent gas. Some of the low-J emission lines of CO and HCO$^+$ isotopologues are more sensitive to the conditions either in the translucent environment or in the dense cold one. We propose a cloud model composed of three homogeneous slabs of gas along each line of sight (LoS), representing an envelope and a shielded inner layer. IRAM-30m data from the ORION-B large program toward the Horsehead nebula are used to demonstrate the method's capability. We use the non-LTE radiative transfer code RADEX to model the line profiles from the kinetic temperature $T_{kin}$, the volume density $n_{H_2}$, kinematics and chemical properties of the different layers. We then use a maximum likelihood estimator to simultaneously fit the lines of the CO and HCO$^+$ isotopologues. We constrain column density ratios to limit the variance on the estimates. This simple heterogeneous model provides good fits of the fitted lines over a large part of the cloud. The decomposition of the intensity into three layers allows to discuss the distribution of the estimated physical/chemical properties along the LoS. About 80$\%$ the CO integrated intensity comes from the envelope, while $\sim55\%$ of that of the (1-0) and (2-1) lines of C$^{18}$O comes from the inner layer. The $N(^{13}CO)/N(C^{18}O)$ in the envelope increases with decreasing $A_v$, and reaches $25$ in the pillar outskirts. The envelope $T_{kin}$ varies from 25 to 40 K, that of the inner layer drops to $\sim 15$ K in the western dense core. The inner layer $n_{H_2}$ is $\sim 3\times10^4\,\text{cm}^{-3}$ toward the filament and it increases by a factor $10$ toward dense cores. The proposed method correctly retrieves the physical/chemical properties of the Horsehead nebula and offers promising prospects for less supervised model fits of wider-field datasets.

We performed time- and polarization-resolved extreme ultraviolet momentum microscopy on topological Dirac semimetal candidate 1T-ZrTe$_2$. Excited states band mapping uncovers the previously inaccessible linear dispersion of the Dirac cone above the Fermi level. We study the orbital texture of bands using linear dichroism in photoelectron angular distributions. These observations provide hints on the topological character of 1T-ZrTe$_2$. Time-, energy- and momentum-resolved nonequilibrium carrier dynamics reveal that intra- and inter-band scattering processes play a capital role in the relaxation mechanism, leading to multivalley electron-hole accumulation near the Fermi level. We also show that electrons' inverse lifetime has a linear dependence on their binding energy. Our time- and polarization-resolved XUV photoemission results shed light on the excited state electronic structure of 1T-ZrTe$_2$ and provide valuable insights into the relatively unexplored field of quantum-state-resolved ultrafast dynamics in 3D topological Dirac semimetals.

The task of content-type detection -- which entails identifying the data encoded in an arbitrary byte sequence -- is critical for operating systems, development, reverse engineering environments, and a variety of security applications. In this paper, we introduce Magika, a novel AI-powered content-type detection tool. Under the hood, Magika employs a deep learning model that can execute on a single CPU with just 1MB of memory to store the model's weights. We show that Magika achieves an average F1 score of 99% across over a hundred content types and a test set of more than 1M files, outperforming all existing content-type detection tools today. In order to foster adoption and improvements, we open source Magika under an Apache 2 license on GitHub and make our model and training pipeline publicly available. Our tool has already seen adoption by the Gmail email provider for attachment scanning, and it has been integrated with VirusTotal to aid with malware analysis. We note that this paper discusses the first iteration of Magika, and a more recent version already supports more than 200 content types. The interested reader can see the latest development on the Magika GitHub repository, available at https://github.com/google/magika.

The application of machine learning to medical ultrasound videos of the heart, i.e., echocardiography, has recently gained traction with the availability of large public datasets. Traditional supervised tasks, such as ejection fraction regression, are now making way for approaches focusing more on the latent structure of data distributions, as well as generative methods. We propose a model trained exclusively by knowledge distillation, either on real or synthetical data, involving retrieving masks suggested by a teacher model. We achieve state-of-the-art (SOTA) values on the task of identifying end-diastolic and end-systolic frames. By training the model only on synthetic data, it reaches segmentation capabilities close to the performance when trained on real data with a significantly reduced number of weights. A comparison with the 5 main existing methods shows that our method outperforms the others in most cases. We also present a new evaluation method that does not require human annotation and instead relies on a large auxiliary model. We show that this method produces scores consistent with those obtained from human annotations. Relying on the integrated knowledge from a vast amount of records, this method overcomes certain inherent limitations of human annotator labeling. Code: https://github.com/GregoirePetit/EchoDFKD

Hymenoscyphus fraxineus is an invasive forest fungal pathogen that induces severe dieback in European ash populations. The spread of the disease has been closely monitored in France by the forest health survey system. We have developed a mechanisticstatistical model that describes the spread of the disease. It takes into account climate (summer temperature and spring rainfall), pathogen population dynamics (foliar infection, Allee effect induced by limited sexual partner encounters) and host density. We fitted this model using available disease reports. We estimated the parameters of our model, first identifying the appropriate ranges for the parameters, which led to a model reduction, and then using an adaptive multiple importance sampling algorithm for fitting. The model reproduces well the propagation observed in France over the last 20 years. In particular, it predicts the absence of disease impact in the south-east of the country and its weak development in the Garonne valley in south-west France. Summer temperature is the factor with the highest overall effect on disease spread, and explains the limited impact in southern France. Among the different temperature indices tested, the number of summer days with temperatures above 28{\textdegree}C gave the best qualitative behavior and the best fit. In contrast, the Allee effect and the heterogeneity of spring precipitation did not strongly affect the overall expansion of H. fraxineus in France and could be neglected in the modeling process. The model can be used to infer the average annual dispersal of H. fraxineus in France.

This article introduces an innovative architecture designed to declaratively combine Large Language Models (LLMs) with shared histories, and triggers to identify the most appropriate LLM for a given task. Our approach is general and declarative, relying on the construction of finite automata coupled with an event management system. The developed tool is crafted to facilitate the efficient and complex integration of LLMs with minimal programming effort, especially, but not only, for integrating methods of positive psychology to AI. The flexibility of our technique is demonstrated through applied examples in automation, communication, and ethics., Comment: Submitted to IAAI-2025, Philadelphia, PA

PLATO (PLAnetary Transits and Oscillations of stars) is ESA's M3 mission designed to detect and characterise extrasolar planets and perform asteroseismic monitoring of a large number of stars. PLATO will detect small planets (down to <2 R_(Earth)) around bright stars (<11 mag), including terrestrial planets in the habitable zone of solar-like stars. With the complement of radial velocity observations from the ground, planets will be characterised for their radius, mass, and age with high accuracy (5 %, 10 %, 10 % for an Earth-Sun combination respectively). PLATO will provide us with a large-scale catalogue of well-characterised small planets up to intermediate orbital periods, relevant for a meaningful comparison to planet formation theories and to better understand planet evolution. It will make possible comparative exoplanetology to place our Solar System planets in a broader context. In parallel, PLATO will study (host) stars using asteroseismology, allowing us to determine the stellar properties with high accuracy, substantially enhancing our knowledge of stellar structure and evolution. The payload instrument consists of 26 cameras with 12cm aperture each. For at least four years, the mission will perform high-precision photometric measurements. Here we review the science objectives, present PLATO's target samples and fields, provide an overview of expected core science performance as well as a description of the instrument and the mission profile at the beginning of the serial production of the flight cameras. PLATO is scheduled for a launch date end 2026. This overview therefore provides a summary of the mission to the community in preparation of the upcoming operational phases.

Main-sequence Radio Pulse emitters (MRPs) are magnetic early-type stars that produce coherent radio emission observed in the form of periodic radio pulses. The emission mechanism behind is the Electron Cyclotron Maser Emission (ECME). Amongst all kinds of magnetospheric emission, ECME is unique due to its high directivity and intrinsically narrow bandwidth. The emission is also highly circularly polarized and the sign of polarization is opposite for the two magnetic hemispheres. This combination of properties makes ECME highly sensitive to the three-dimensional structures in the stellar magnetospheres. This is especially significant for late-B and A-type magnetic stars that do not emit other types of magnetospheric emission such as Halpha, the key probe used to trace magnetospheric densities. In this paper, we use ultra-wideband observation (0.4-2 GHz) of a late B-type MRP HD 133880 to demonstrate how we can extract information on plasma distribution from ECME. We achieve this by examining the differences in pulse arrival times ('lags') as a function of frequencies, and qualitatively comparing those with lags obtained by simulating ECME ray paths in hot stars' magnetospheres. This reveals that the stellar magnetosphere has a disk-like overdensity inclined to the magnetic equator with a centrally concentrated density that primarily affects the intermediate frequencies (400-800 MHz). This result, which is consistent with recent density model proposed for hotter centrifugally supported magnetospheres, lends support to the idea of a unifying model for magnetospheric operations in early-type stars, and also provides further motivation to fully characterize the ECME phenomenon in large-scale stellar magnetospheres., Comment: Accepted for publication in ApJ

Observations of ionic, atomic, or molecular lines are performed to improve our understanding of the interstellar medium (ISM). However, the potential of a line to constrain the physical conditions of the ISM is difficult to assess quantitatively, because of the complexity of the ISM physics. The situation is even more complex when trying to assess which combinations of lines are the most useful. Therefore, observation campaigns usually try to observe as many lines as possible for as much time as possible. We search for a quantitative statistical criterion to evaluate the constraining power of a (or combination of) tracer(s) with respect to physical conditions in order to improve our understanding of the statistical relationships between ISM tracers and physical conditions and helps observers to motivate their observation proposals. The best tracers are obtained by comparing the mutual information between a physical parameter and different sets of lines. We apply this method to simulations of radio molecular lines emitted by a photodissociation region similar to the Horsehead Nebula that would be observed at the IRAM 30m telescope. We search for the best lines to constrain the visual extinction $A_v^{tot}$ or the far UV illumination $G_0$. The most informative lines change with the physical regime (e.g., cloud extinction). Short integration time of the CO isotopologue $J=1-0$ lines already yields much information on the total column density most regimes. The best set of lines to constrain the visual extinction does not necessarily combine the most informative individual lines. Precise constraints on $G_0$ are more difficult to achieve with molecular lines. They require spectral lines emitted at the cloud surface (e.g., [CII] and [CI] lines). This approach allows one to better explore the knowledge provided by ISM codes, and to guide future observation campaigns.

The $\epsilon$ Lupi A (HD 136504) system stands out among magnetic massive binaries as the only short-period binary system in which both components have detectable magnetic fields. The proximity of the magnetospheres of the components leads to magnetospheric interactions, which are revealed as periodic pulses in the radio light curve of this system. In this work, we aim to investigate the magnetospheric interaction phenomenon in the X-ray domain. We observed this system with the XMM-Newton telescope, covering its orbital period. We observe variable X-ray emission with maximum flux near periastron, showing similarity with radio observations. The X-ray spectra show significantly elevated hard X-ray flux during periastron. We attribute the soft X-ray emission to individual magnetospheres, while the hard X-ray emission is explained by magnetospheric interaction, particularly due to magnetic reconnection. However, unlike in the radio, we do not find any significant short-term X-ray bursts. This exotic system can be an ideal target to study magnetospheric interactions in close binaries with organized magnetospheres., Comment: Accepted for publication in ApJ, 16 pages, 11 figures

The gas-phase abundance of carbon, x_C = C/H, and its depletion factors are essential parameters for understanding the gas and solid compositions that are ultimately incorporated into planets. The majority of protoplanetary disks are born in clusters and, as a result, are exposed to external FUV radiation. These FUV photons potentially affect the disk's evolution, chemical composition, and line excitation. We present the first detection of the [CI]609um fine-structure line of neutral carbon (CI), achieved with ALMA, toward one of these disks, d203-506, in the Orion Nebula Cluster. We also report the detection of CI forbidden and permitted lines (from electronically excited states up to 10 eV) observed with JWST in the IR. These lines trace the irradiated outer disk and photo-evaporative wind. Contrary to the common belief that these IR lines are C+ recombination lines, we find that they are dominated by FUV-pumping of CI followed by fluorescence cascades. They trace the transition from atomic to molecular gas, and their intensities scale with G0. The lack of outstanding IR OI fluorescent emission, however, implies a sharper attenuation of external FUV radiation with E > 12 eV (~Lyman-beta). This is related to a lower effective FUV dust absorption cross section compared to that of interstellar grains, implying a more prominent role for FUV shielding by the CI photoionization continuum. The [CI]609um intensity is proportional to N(CI) and can be used to infer x_C. We derive x_C ~ 1.4E-4. This implies that there is no major depletion of volatile carbon compared to x_C measured in the natal cloud, hinting at a young disk. We also show that external FUV radiation impacts the outer disk and wind by vertically shifting the water freeze-out depth, which results in less efficient grain growth and settling. This shift leads to nearly solar gas-phase C/O abundance ratios in these irradiated layers., Comment: Accepted for publication in A&A Letters. 14 pages including Appendices

This paper analyses spectropolarimetric observations of the classical T Tauri star (CTTS) GM Aurigae collected with SPIRou, the near-infrared spectropolarimeter at the Canada-France-Hawaii Telescope, as part of the SLS and SPICE Large Programs. We report for the first time results on the large-scale magnetic field at the surface of GM Aur using Zeeman Doppler imaging. Its large-scale magnetic field energy is almost entirely stored in an axisymmetric poloidal field, which places GM Aur close to other CTTSs with similar internal structures. A dipole of about 730 G dominates the large-scale field topology, while higher-order harmonics account for less than 30 per-cent of the total magnetic energy. Overall, we find that the main difference between our three reconstructed maps (corresponding to sequential epochs) comes from the evolving tilt of the magnetic dipole, likely generated by non-stationary dynamo processes operating in this largely convective star rotating with a period of about 6 d. Finally, we report a 5.5$\sigma$ detection of a signal in the activity-filtered radial velocity data of semi-amplitude 110 $\pm$ 20 m/s at a period of 8.745 $\pm$ 0.009 d. If attributed to a close-in planet in the inner accretion disc of GM Aur, it would imply that this planet candidate has a minimum mass of 1.10 $\pm$ 0.30 Mjup and orbits at a distance of 0.082 $\pm$ 0.002 au., Comment: Published in MNRAS. 24 pages, 15 figures

The $\gamma$-linear projected barcode was recently introduced as an alternative to the well-known fibered barcode for multiparameter persistence, in which restrictions of the modules to lines are replaced by pushforwards of the modules along linear forms in the polar of some fixed cone $\gamma$. So far, the computation of the $\gamma$-linear projected barcode has only been studied in the functional setting, in which persistence modules come from the persistent cohomology of $\mathbb{R}^n$-valued functions. Here we develop a method that works in the algebraic setting directly, for any multiparameter persistence module over $\mathbb{R}^n$ that is given via a finite free resolution. Our approach is similar to that of RIVET: first, it pre-processes the resolution to build an arrangement in the dual of $\mathbb{R}^n$ and a barcode template in each face of the arrangement; second, given any query linear form $u$ in the polar of $\gamma$, it locates $u$ within the arrangement to produce the corresponding barcode efficiently. While our theoretical complexity bounds are similar to the ones of RIVET, our arrangement turns out to be simpler thanks to the linear structure of the space of linear forms. Our theoretical analysis combines sheaf-theoretic and module-theoretic techniques, showing that multiparameter persistence modules can be converted into a special type of complexes of sheaves on vector spaces called conic-complexes, whose derived pushforwards by linear forms have predictable barcodes., Comment: 34 pages, 3 figures

Given a digraph, an ordering of its vertices defines a backedge graph, namely the undirected graph whose edges correspond to the arcs pointing backwards with respect to the order. The degreewidth of a digraph is the minimum over all ordering of the maximum degree of the backedge graph. We answer an open question by Keeney and Lokshtanov [WG 2024], proving that it is \NP-hard to determine whether an oriented graph has degreewidth at most $1$, which settles the last open case for oriented graphs. We complement this result with a general discussion on parameters defined using backedge graphs and their relations to classical parameters.

The first generation of ELT instruments includes an optical-infrared high-resolution spectrograph, indicated as ELT-HIRES and recently christened ANDES (ArmazoNes high Dispersion Echelle Spectrograph). ANDES consists of three fibre-fed spectrographs ([U]BV, RIZ, YJH) providing a spectral resolution of $\sim$100,000 with a minimum simultaneous wavelength coverage of 0.4-1.8 $\mu$m with the goal of extending it to 0.35-2.4 $\mu$m with the addition of a U arm to the BV spectrograph and a separate K band spectrograph. It operates both in seeing- and diffraction-limited conditions and the fibre feeding allows several, interchangeable observing modes including a single conjugated adaptive optics module and a small diffraction-limited integral field unit in the NIR. Modularity and fibre-feeding allow ANDES to be placed partly on the ELT Nasmyth platform and partly in the Coud\'e room. ANDES has a wide range of groundbreaking science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Among the top science cases, there are the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars, tests on the stability of Nature's fundamental couplings, and the direct detection of the cosmic acceleration. The ANDES project is carried forward by a large international consortium, composed of 35 Institutes from 13 countries, forming a team of almost 300 scientists and engineers which include the majority of the scientific and technical expertise in the field that can be found in ESO member states., Comment: SPIE astronomical telescope and instrumentation 2024, in press

Observing exoplanets through transmission spectroscopy supplies detailed information on their atmospheric composition, physics, and chemistry. Prior to JWST, these observations were limited to a narrow wavelength range across the near-ultraviolet to near-infrared, alongside broadband photometry at longer wavelengths. To understand more complex properties of exoplanet atmospheres, improved wavelength coverage and resolution are necessary to robustly quantify the influence of a broader range of absorbing molecular species. Here we present a combined analysis of JWST transmission spectroscopy across four different instrumental modes spanning 0.5-5.2 micron using Early Release Science observations of the Saturn-mass exoplanet WASP-39b. Our uniform analysis constrains the orbital and stellar parameters within sub-percent precision, including matching the precision obtained by the most precise asteroseismology measurements of stellar density to-date, and further confirms the presence of Na, K, H$_2$O, CO, CO$_2$, and SO$_2$ atmospheric absorbers. Through this process, we also improve the agreement between the transmission spectra of all modes, except for the NIRSpec PRISM, which is affected by partial saturation of the detector. This work provides strong evidence that uniform light curve analysis is an important aspect to ensuring reliability when comparing the high-precision transmission spectra provided by JWST., Comment: 34 pages, 11 figures, 3 tables. Nat Astron (2024)

We present new near-ultraviolet (NUV, $\lambda$ = 2479 $-$ 3306 $\r{A}$) transmission spectroscopy of KELT-9b, the hottest known exoplanet, obtained with the Colorado Ultraviolet Transit Experiment ($CUTE$) CubeSat. Two transits were observed on September 28th and September 29th 2022, referred to as Visits 1 and 2 respectively. Using a combined transit and systematics model for each visit, the best-fit broadband NUV light curves are R$_{\text{p}}$/R$_{\star}$ $=$ 0.136$_{0.0146}^{0.0125}$ for Visit 1 and R$_{\text{p}}$/R$_{\star}$ $=$ 0.111$_{0.0190}^{0.0162}$ for Visit 2, appearing an average of 1.54$\times$ larger in the NUV than at optical wavelengths. While the systematics between the two visits vary considerably, the two broadband NUV light curves are consistent with each other. A transmission spectrum with 25 $\r{A}$ bins suggests a general trend of excess absorption in the NUV, consistent with expectations for ultra-hot Jupiters. Although we see an extended atmosphere in the NUV, the reduced data lack the sensitivity to probe individual spectral lines.

The nature of the close-in rocky planet 55 Cnc e is puzzling despite having been observed extensively. Its optical and infrared occultation depths show temporal variability, in addition to a phase curve variability observed in the optical. We wish to explore the possibility that the variability originates from the planet being in a 3:2 spin-orbit resonance, thus showing different sides during occultations. We proposed and were awarded Cycle 1 time at the James Webb Space Telescope (JWST) to test this hypothesis. JWST/NIRCam observed five occultations (secondary eclipses), of which four were observed within a week, of the planet simultaneously at 2.1 and 4.5 {\mu}m. While the former gives band-integrated photometry, the latter provides a spectrum between 3.9-5.0 {\mu}m. We find that the occultation depths in both bandpasses are highly variable and change between a non-detection (-5 +/- 6 ppm and 7 +/- 9 ppm) to 96 +/- 8 ppm and 119 (+34) (-19) ppm at 2.1 {\mu}m and 4.5 {\mu}m, respectively. Interestingly, the variations in both bandpasses are not correlated and do not support the 3:2 spin-orbit resonance explanation. The measured brightness temperature at 4.5 {\mu}m varies between 873-2256 K and is lower than the expected dayside temperature of bare rock with no heat re-distribution (2500 K) which is indicative of an atmosphere. Our atmospheric retrieval analysis of occultation depth spectra at 4.5 {\mu}m finds that different visits statistically favour various atmospheric scenarios including a thin outgassed CO/CO2 atmosphere and a silicate rock vapour atmosphere. Some visits even support a flat line model. The observed variability could be explained by stochastic outgassing of CO/CO2, which is also hinted by retrievals. Alternatively, the variability, observed at both 2.1 and 4.5 {\mu}m, could be the result of a circumstellar patchy dust torus generated by volcanism on the planet., Comment: 32 pages, 10 + 15 figures, 3+2 tables, accepted for publication in A&A

Traditional single-fibre spectroscopy provides a single galaxy spectrum, forming the basis for crucial parameter estimation. However, its accuracy can be compromised by various sources of contamination, such as the prominent \Ha~emission line originating from both Star-Forming (SF) regions and non-Star-Forming regions (NonSF), including Active Galactic Nuclei (AGN). The potential to dissect a spectrum into its SF and NonSF constituents holds the promise of significantly enhancing precision in parameter estimates. In contrast, Integral Field Unit (IFU) surveys present a solution to minimize contamination. These surveys examine spatially localized regions within galaxies, reducing the impact of mixed sources. Although an IFU survey's resulting spectrum covers a smaller region of a galaxy than single-fibre spectroscopy, it can still encompass a blend of heterogeneous sources. Our study introduces an innovative model informed by insights from the MaNGA IFU survey. This model enables the decomposition of galaxy spectra, including those from the Sloan Digital Sky Survey (SDSS), into SF and NonSF components. Applying our model to these survey datasets produces two distinct spectra, one for SF and another for NonSF components, while conserving flux across wavelength bins. When these decomposed spectra are visualized on a BPT diagram, interesting patterns emerge. There is a significant shift in the placement of the NonSF decomposed spectra, as well as the emergence of two distinct clusters in the LINER and Seyfert regions. This shift highlights the key role of SF `contamination' in influencing the positioning of NonSF spectra within the BPT diagram., Comment: 20 pages, 15 figures. Accepted for publication in APJ

Floating-point accuracy is an important concern when developing numerical simulations or other compute-intensive codes. Tracking the introduction of numerical regression is often delayed until it provokes unexpected bug for the end-user. In this paper, we introduce Verificarlo CI, a continuous integration workflow for the numerical optimization and debugging of a code over the course of its development. We demonstrate applicability of Verificarlo CI on two test-case applications.

This work explores how to fine-tune large language models using prompt engineering techniques with contextual information for generating an accurate text description of the full story, ready to be forwarded to off-the-shelve speech synthesis tools. We propose to use existing computer vision and optical character recognition techniques to build a grounded context from the comic strip image content, such as panels, characters, text, reading order and the association of bubbles and characters. Then we infer character identification and generate comic book script with context-aware panel description including character's appearance, posture, mood, dialogues etc. We believe that such enriched content description can be easily used to produce audiobook and eBook with various voices for characters, captions and playing sound effects., Comment: Accepted to MANPU 2024 (Athens, Greece, August 30, 2024)

In the context of low-viscosity protoplanetary discs (PPDs), the formation scenarios of the Solar System should be revisited. In particular, the Jupiter-Saturn pair has been shown to lock in the 2:1 mean motion resonance while migrating generally inwards, making the Grand Tack scenario impossible. We explore what resonant chains of multiple giant planets can form in a low-viscosity disc, and whether these configurations can evolve into forming the Solar System in the post gas disc phase. We used hydrodynamical simulations to study the migration of the giant planets in a disc with viscosity $\alpha=10^{-4}$. After a transition phase to a gas-less configuration, we studied the stability of the obtained resonant chains through their interactions with a disc of leftover planetesimals by performing N-body simulations using rebound. The gaps open by giant planets are wider and deeper for lower viscosity, reducing the damping effect of the disc and thus weakening resonant chains. Exploring numerous configurations, we found five stable resonant chains of four or five planets. In a thin PPD, the four giant planets revert their migration and migrate outwards. After disc dispersal, under the influence of a belt of planetesimals, some resonant chains undergo an instability phase while others migrate smoothly over a billion years. For three of our resonant chains, about 1% of the final configurations pass the four criteria to fit the Solar System. The most successful runs are obtained for systems formed in a cold PPD with a massive planetesimal disc. This work provides a fully consistent study of the dynamical history of the Solar System's giant planets, from the protoplanetary disc phase up to the giant planet instability. Although building resonant configurations is difficult in low-viscosity discs, we find it possible to reproduce the Solar System from a cold, low-viscosity protoplanetary disc., Comment: 13 Pages, 13 Figures, Accepted for publications in A&A

CryptoGPT: a 7B model competing with GPT-4 in a specific task -- The Impact of Automatic Annotation and Strategic Fine-Tuning via QLoRAIn this article, we present a method aimed at refining a dedicated LLM of reasonable quality with limited resources in an industrial setting via CryptoGPT. It is an LLM designed for financial news analysis for the cryptocurrency market in real-time. This project was launched in an industrial context. This model allows not only for the classification of financial information but also for providing comprehensive analysis. We refined different LLMs of the same size such as Mistral-7B and LLama-7B using semi-automatic annotation and compared them with various LLMs such as GPT-3.5 and GPT-4. Our goal is to find a balance among several needs: 1. Protecting data (by avoiding their transfer to external servers), 2. Limiting annotation cost and time, 3. Controlling the model's size (to manage deployment costs), and 4. Maintaining better analysis quality., Comment: Journ{\'e}e Nationale sur la Fouille de Textes, Pascal CUXAC; Adrien GUILLE; C{\'e}dric LOPEZ, Jun 2024, Lyon (Universit{\'e} Lumi{\`e}re Lyon 2), France

The ever-increasing demand for efficient data storage and processing has fueled the search for novel memory devices. Spintronics offers an alternative fast and efficient solution using spin-to-charge interconversion. In this work, we demonstrate a remarkable thirty-four-fold increase in spin-to-charge current conversion when incorporating a 2D epitaxial graphene monolayer between iron and platinum layers by exploring spin-pumping on-chip devices. Furthermore, we find that the spin conversion is also anisotropic. We attribute this enhancement and anisotropy to the asymmetric Rashba contributions driven by an unbalanced spin accumulation at the differently hybridized top and bottom graphene interfaces, as highlighted by ad-hoc first-principles theory. The improvement in spin-to-charge conversion as well as its anisotropy reveals the importance of interfaces in hybrid 2D-thin film systems opening up new possibilities for engineering spin conversion in 2D materials, leading to potential advances in memory, logic applications, or unconventional computing., Comment: 33 pages with double-spaced paragraphs. 23 pages without references. 4 figures and one extended figure. Supplementary information, not shown, contains 21 pages and 23 supplementary figures

The accurate characterisation of the stellar magnetism of planetary host stars has been gaining momentum, especially in the context of transmission spectroscopy investigations of exoplanets. Indeed, the magnetic field regulates the amount of energetic radiation and stellar wind impinging on planets, as well as the presence of inhomogeneities on the stellar surface that hinder the precise extraction of the planetary atmospheric absorption signal. We initiated a spectropolarimetric campaign to unveil the magnetic field properties of known exoplanet hosting stars included in the current list of potential Ariel targets. In this work, we focus on HD 63433, a young solar-like star hosting two sub-Neptunes and an Earth-sized planet. These exoplanets orbit within 0.15 au from the host star and have likely experienced different atmospheric evolutionary paths. We analysed optical spectropolarimetric data collected with ESPaDOnS, HARPSpol, and Neo-Narval to compute the magnetic activity indices (log R'_HK , H$\alpha$, and Ca ii infrared triplet), measure the longitudinal magnetic field, and reconstruct the large-scale magnetic topology via Zeeman-Doppler imaging (ZDI). The magnetic field map was then employed to simulate the space environment in which the exoplanets orbit. The reconstructed stellar magnetic field has an average strength of 24 G and it features a complex topology with a dominant toroidal component, in agreement with other stars of a similar spectral type and age. Our simulations of the stellar environment locate 10% of the innermost planetary orbit inside the Alfv\'en surface and, thus, brief magnetic connections between the planet and the star can occur. The outer planets are outside the Alfv\'en surface and a bow shock between the stellar wind and the planetary magnetosphere could potentially form., Comment: 13 pages, 11 figures and 4 tables. Accepted in Astronomy and Astrophysics

Creating defects in graphene by hydrogenation, either to achieve hydrogen chemisorption or partial etching, is a way to open an electronic band gap in graphene. Understanding the range of stability conditions of partially etched or hydrogenated graphene is crucial for application, as processing conditions (e.g. temperature) and quality control (characterization) conditions may result in modifying the material through partial or full dehydrogenation, and subsequent alteration of its electronic properties. This work reports a study of various dehydrogenation conditions of hydrogenated or hydrogen-etched monolayer graphene (1LG), either free-standing or supported by an interferential (SiO2/Si) substrate, using incremental annealing under nitrogen atmosphere up to 400 {\textdegree}C. Materials were investigated by Raman spectroscopy. Indeed, it has been known since 2012 that the intensity ratio of two Raman bands activated by double resonance, D over D' (ID/ID') can be used to identify the type of defects in defective graphene. It is shown that hydrogenated 1LG, characterized by a large ID/ID' ratio (~9-15), is stable provided annealing remains below 300 {\textdegree}C. On the other hand, defective 1LG resulting from hydrogen etching remains stable up to 400 {\textdegree}C, whether the 1LG is hydrogenated on one side or both sides, while a modification in the type and proportions of defects is likely. Experimental conditions for the safe use of Raman spectroscopy, otherwise able to induce specimen overheating because of the laser energy and power, are also determined and discussed.

The new generation of observatories and instruments (VLT/ERIS, JWST, ELT) motivate the development of robust methods to detect and characterise faint and close-in exoplanets. Molecular mapping and cross-correlation for spectroscopy use molecular templates to isolate a planet's spectrum from its host star. However, reliance on signal-to-noise ratio (S/N) metrics can lead to missed discoveries, due to strong assumptions of Gaussian independent and identically distributed noise. We introduce machine learning for cross-correlation spectroscopy (MLCCS); the method aims to leverage weak assumptions on exoplanet characterisation, such as the presence of specific molecules in atmospheres, to improve detection sensitivity for exoplanets. MLCCS methods, including a perceptron and unidimensional convolutional neural networks, operate in the cross-correlated spectral dimension, in which patterns from molecules can be identified. We test on mock datasets of synthetic planets inserted into real noise from SINFONI at K-band. The results from MLCCS show outstanding improvements. The outcome on a grid of faint synthetic gas giants shows that for a false discovery rate up to 5%, a perceptron can detect about 26 times the amount of planets compared to an S/N metric. This factor increases up to 77 times with convolutional neural networks, with a statistical sensitivity shift from 0.7% to 55.5%. In addition, MLCCS methods show a drastic improvement in detection confidence and conspicuity on imaging spectroscopy. Once trained, MLCCS methods offer sensitive and rapid detection of exoplanets and their molecular species in the spectral dimension. They handle systematic noise and challenging seeing conditions, can adapt to many spectroscopic instruments and modes, and are versatile regarding atmospheric characteristics, which can enable identification of various planets in archival and future data., Comment: 27 pages, 24 figures. Submitted for publication in A&A January 2, 2024. After first iteration with the referee, resubmitted May 17, 2024

In this study, we investigate the spin-charge current conversion characteristics of chemically disordered ferromagnetic single FePt thin films by spin-pumping ferromagnetic resonance experiments performed on both a resonance cavity and on patterned devices. We clearly observe a self-induced signal in a single FePt layer. The sign of a single FePt spin pumping voltage signal is consistent with a typical bilayer with a positive spin Hall angle layer such as that of Pt on top of a ferromagnet (FM), substrate//FM/Pt. Structural analysis shows a strong composition gradient due to natural oxidation at both FePt interfaces, with the Si substrate and with the air. The FePt-thickness dependence of the self-induced charge current produced allowed us to obtain $\lambda _ \text{FePt}=(1.5\pm 0.1)$ nm and self-induced $\theta_ \text{self-FePt}=0.047 \pm 0.003$, with efficiency for reciprocal effects applications $\theta _ \text{self-FePt} \times \lambda _ \text{FePt} = 0.071$ nm which is comparable to that of Pt, $\theta _ \text{SH-Pt} \times \lambda _ \text{Pt} = 0.2$ nm. Moreover, by studying bilayer systems such as Si//FePt/Pt and Si//Pt//FePt we independently could extract the individual contributions of the external inverse spin Hall effect of Pt and the self-induced inverse spin Hall effect of FePt. Notably, this method gives consistent values of charge currents produced due to only self-induced inverse spin Hall effect in FePt layers. These results advance our understanding of spin-to-charge interconversion mechanisms in composite thin films and pave the way for the development of next-generation spintronics devices based on self-torque., Comment: 13 pages, 7 figures

Understanding the causal impact of medical interventions is essential in healthcare research, especially through randomized controlled trials (RCTs). Despite their prominence, challenges arise due to discrepancies between treatment allocation and actual intake, influenced by various factors like patient non-adherence or procedural errors. This paper focuses on the Complier Average Causal Effect (CACE), crucial for evaluating treatment efficacy among compliant patients. Existing methodologies often rely on assumptions such as exclusion restriction and monotonicity, which can be problematic in practice. We propose a novel approach, leveraging supervised learning architectures, to estimate CACE without depending on these assumptions. Our method involves a two-step process: first estimating compliance probabilities for patients, then using these probabilities to estimate two nuisance components relevant to CACE calculation. Building upon the principal ignorability assumption, we introduce four root-n consistent, asymptotically normal, CACE estimators, and prove that the underlying mixtures of experts' nuisance components are identifiable. Our causal framework allows our estimation procedures to enjoy reduced mean squared errors when exclusion restriction or monotonicity assumptions hold. Through simulations and application to a breastfeeding promotion RCT, we demonstrate the method's performance and applicability.

We use the magnetic field components measured by Zeeman Doppler imaging (ZDI) to calculate the stellar surface force and torque due to magnetic stresses for the fast rotators $\sigma$ Ori E, 36 Lyn and CU Vir, and the slow rotator $\tau$ Sco. If we assume the stars have spherical photospheres, the estimated torques give spin down time scales no larger than $7 \times 10^5$ yr. For $\sigma$ Ori E, the predicted spin down time scale, $\simeq 6000$ yr, is much less than the observationally measured time scale of $\simeq 10^6$ yr. However, for CU Vir, we find that the spin down time scale from its ZDI map is $7 \times 10^5$ yr in good agreement with its average rate of spin down from 1960 to 2010. With the exception of $\tau$ Sco, the net force due to magnetic stresses at the stellar surface are large compared to the surface-integrated pressure. We discuss possible reasons for the large values of the forces (and torques), and suggest that the likely explanation is that rotation and the magnetic stresses create significant departures from spherical symmetry., Comment: To appear in MNRAS

One of the main problems in astrochemistry is determining the amount of sulfur in volatiles and refractories in the interstellar medium. The detection of the main sulfur reservoirs (icy H$_2$S and atomic gas) has been challenging, and estimates are based on the reliability of models to account for the abundances of species containing less than 1% of the total sulfur. The high sensitivity of the James Webb Space Telescope provides an unprecedented opportunity to estimate the sulfur abundance through the observation of the [S I] 25.249 $\mu$m line. We used the [S III] 18.7 $\mu$m, [S IV] 10.5 $\mu$m, and [S l] 25.249 $\mu$m lines to estimate the amount of sulfur in the ionized and molecular gas along the Orion Bar. For the theoretical part, we used an upgraded version of the Meudon photodissociation region (PDR) code to model the observations. New inelastic collision rates of neutral atomic sulfur with ortho- and para- molecular hydrogen were calculated to predict the line intensities. The [S III] 18.7 $\mu$m and [S IV] 10.5 $\mu$m lines are detected over the imaged region with a shallow increase (by a factor of 4) toward the HII region. We estimate a moderate sulfur depletion, by a factor of $\sim$2, in the ionized gas. The corrugated interface between the molecular and atomic phases gives rise to several edge-on dissociation fronts we refer to as DF1, DF2, and DF3. The [S l] 25.249 $\mu$m line is only detected toward DF2 and DF3, the dissociation fronts located farthest from the HII region. The detailed modeling of DF3 using the Meudon PDR code shows that the emission of the [S l] 25.249 $\mu$m line is coming from warm ($>$ 40 K) molecular gas located at A$_{\rm V}$ $\sim$ 1$-$5 mag from the ionization front. Moreover, the intensity of the [S l] 25.249 $\mu$m line is only accounted for if we assume the presence of undepleted sulfur., Comment: 16 pages, 6 figures. Accepted for publication in Astronomy and Astrophysics

Strong-field ionization by counter-rotating two-color laser fields produces quantum interference between photoelectrons emitted on the leading and trailing edges of the laser field oscillations. We show that in chiral molecules, this interference is asymmetric along the light propagation direction and strongly enhances the sensitivity of the attoclock scheme to molecular chirality. Calculations in a toy-model molecule with a short-range chiral potential show that this enhanced sensitivity already emerges at the exit of the tunnel. We investigate the possible sources of chiral sensitivity in the tunneling process, and find that the interference between electron vortices plays a crucial role in the chiral response.

Mid-infrared emission features probe the properties of ionized gas, and hot or warm molecular gas. The Orion Bar is a frequently studied photodissociation region (PDR) containing large amounts of gas under these conditions, and was observed with the MIRI IFU aboard JWST as part of the "PDRs4All" program. The resulting IR spectroscopic images of high angular resolution (0.2") reveal a rich observational inventory of mid-IR emission lines, and spatially resolve the substructure of the PDR, with a mosaic cutting perpendicularly across the ionization front and three dissociation fronts. We extracted five spectra that represent the ionized, atomic, and molecular gas layers, and measured the most prominent gas emission lines. An initial analysis summarizes the physical conditions of the gas and the potential of these data. We identified around 100 lines, report an additional 18 lines that remain unidentified, and measured the line intensities and central wavelengths. The H I recombination lines originating from the ionized gas layer bordering the PDR, have intensity ratios that are well matched by emissivity coefficients from H recombination theory, but deviate up to 10% due contamination by He I lines. We report the observed emission lines of various ionization stages of Ne, P, S, Cl, Ar, Fe, and Ni, and show how certain line ratios vary between the five regions. We observe the pure-rotational H$_2$ lines in the vibrational ground state from 0-0 S(1) to 0-0 S(8), and in the first vibrationally excited state from 1-1 S(5) to 1-1 S(9). We derive H$_2$ excitation diagrams, and approximate the excitation with one thermal (~700 K) component representative of an average gas temperature, and one non-thermal component (~2700 K) probing the effect of UV pumping. We compare these results to an existing model for the Orion Bar PDR and highlight the differences with the observations., Comment: 26 pages, 12 figures, 3 tables. Submitted to A&A, under review (1st revision)

Robust radiative transfer techniques are requisite for efficiently extracting the physical and chemical information from molecular rotational lines.We study several hypotheses that enable robust estimations of the column densities and physical conditions when fitting one or two transitions per molecular species. We study the extent to which simplifying assumptions aimed at reducing the complexity of the problem introduce estimation biases and how to detect them.We focus on the CO and HCO+ isotopologues and analyze maps of a 50 square arcminutes field. We used the RADEX escape probability model to solve the statistical equilibrium equations and compute the emerging line profiles, assuming that all species coexist. Depending on the considered set of species, we also fixed the abundance ratio between some species and explored different values. We proposed a maximum likelihood estimator to infer the physical conditions and considered the effect of both the thermal noise and calibration uncertainty. We analyzed any potential biases induced by model misspecifications by comparing the results on the actual data for several sets of species and confirmed with Monte Carlo simulations. The variance of the estimations and the efficiency of the estimator were studied based on the Cram{\'e}r-Rao lower bound.Column densities can be estimated with 30% accuracy, while the best estimations of the volume density are found to be within a factor of two. Under the chosen model framework, the peak 12CO(1--0) is useful for constraining the kinetic temperature. The thermal pressure is better and more robustly estimated than the volume density and kinetic temperature separately. Analyzing CO and HCO+ isotopologues and fitting the full line profile are recommended practices with respect to detecting possible biases.Combining a non-local thermodynamic equilibrium model with a rigorous analysis of the accuracy allows us to obtain an efficient estimator and identify where the model is misspecified. We note that other combinations of molecular lines could be studied in the future., Comment: Astronomy and Astrophysics - A\&A, In press

Measuring the abundances of C- and O-bearing species in exoplanet atmospheres enables us to constrain the C/O ratio, that contains indications about the planet formation history. With a wavelength coverage going from 0.95 to 2.5 microns, the high-resolution (R$\sim$70 000) spectropolarimeter SPIRou can detect spectral lines of major bearers of C and O in exoplanets. Here we present our study of SPIRou transmission spectra of WASP-76 b acquired for the ATMOSPHERIX program. We applied the publicly available data analysis pipeline developed within the ATMOSPHERIX consortium, analysing the data using 1-D models created with the petitRADTRANS code, with and without a grey cloud deck. We report the detection of H$_2$O and CO at a Doppler shift of around -6 km.s$^{-1}$, consistent with previous observations of the planet. Finding a deep cloud deck to be favoured, we measured in mass mixing ratio (MMR) log(H$_2$O)$_{MMR}$ = -4.52 $\pm$ 0.77 and log(CO)$_{MMR}$ = -3.09 $\pm$ 1.05 consistent with a sub-solar metallicity to more than 1$\sigma$. We report 3$\sigma$ upper limits for the abundances of C$_2$H$_2$, HCN and OH. We estimated a C/O ratio of 0.94 $\pm$ 0.39 ($\sim$ 1.7 $\pm$ 0.7 x solar, with errors indicated corresponding to the 2$\sigma$ values) for the limbs of WASP-76 b at the pressures probed by SPIRou. We used 1-D ATMO forward models to verify the validity of our estimation. Comparing them to our abundance estimations of H$_2$O and CO, as well as our upper limits for C$_2$H$_2$, HCN and OH, we found that our results were consistent with a C/O ratio between 1 and 2 x solar, and hence with our C/O estimation. Finally, we found indications of asymmetry for both H$_2$O and CO when investigating the dynamics of their signatures, pointing to a complex scenario involving possibly both a temperature difference between limbs and clouds being behind the asymmetry this planet is best known for., Comment: 20 pages, 19 figures, accepted for publication in A&A

A well-known result due to Caro (1979) and Wei (1981) states that every graph $G$ has an independent set of size at least $\sum_{v\in V(G)} \frac{1}{d(v) + 1}$, where $d(v)$ denotes the degree of vertex $v$. Alon, Kahn, and Seymour (1987) showed the following generalization: For every $k\geq 0$, every graph $G$ has a $k$-degenerate induced subgraph with at least $\sum_{v \in V(G)}\min\{1, \frac {k+1}{d(v)+1}\}$ vertices. In particular, for $k=1$, every graph $G$ with no isolated vertices has an induced forest with at least $\sum_{v\in V(G)} \frac{2}{d(v) + 1}$ vertices. Akbari, Amanihamedani, Mousavi, Nikpey, and Sheybani (2019) conjectured that, if $G$ has minimum degree at least $2$, then one can even find an induced linear forest of that order in $G$, that is, a forest where each component is a path. In this paper, we prove this conjecture and show a number of related results. In particular, if there is no restriction on the minimum degree of $G$, we show that there are infinitely many ``best possible'' functions $f$ such that $\sum_{v\in V(G)} f(d(v))$ is a lower bound on the maximum order of a linear forest in $G$, and we give a full characterization of all such functions $f$.

The poorly studied variable star V390 Sco, previously classified as a Mira pulsator, was detected in a brightening event by the ESA Gaia satellite in September 2023. This work presents an analysis of available archival multifrequency photometric data of this target, along with our spectroscopic observations. Our findings lead to the conclusion that V390 Sco is a new symbiotic star identified by Gaia, currently undergoing a classical symbiotic outburst. Additionally, we uncovered three prior outbursts of this system through archival photometry. The outbursts recur approximately every 2330 - 2400 days, and we hypothesize the periastron passage in an eccentric orbit may trigger them, similarly to the case of BX Mon, DD Mic, or MWC 560. A detailed investigation into the nature of the donor star suggested that V390 Sco is an S-type symbiotic star, likely hosting a less evolved, semiregularly pulsating giant donor, but not a Mira variable., Comment: 9 pages, 9 figures, 1 table; accepted in Astronomische Nachrichten