High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Testing Source Dependence in Gravitational-Wave Tests of General Relativity with Mutual Information
Yi-Fan Wang
Phenomenological deviation parameters used in gravitational-wave tests of general relativity need not represent universal fundamental properties of the sources. Instead, a deviation parameter can be a derived quantity that depends on source properties. Apparent violations of general relativity arising from waveform systematics or data-quality issues can also depend on source properties. In addition to diagnosing individual events, it is helpful to identify systematic trends at the population level. We introduce a nonparametric framework that uses mutual information to test whether the deviations depend on source properties. We validate the framework using simulations with massive graviton waveforms. Assuming we do not have prior knowledge of the underlying theory, massive graviton effects can be captured by a parameterized post-Einstein coefficient that is expected to depend on the luminosity distance and source mass. The results show that the mass and distance dependencies become clear for graviton masses of $\geq 1\times10^{-22}\,\mathrm{eV}$ at detector sensitivities representative of the current fourth observing run, while the controlled general relativity simulations yield null results. We then analyze public real-data products for tests of general relativity from GWTC-4.0 and 4-OGC, including phenomenological parameterized tests, modified dispersion tests, and parity violation tests. The phenomenological deviation parameters have tentative correlations with effective
spin, and correlations of modified-dispersion or parity-violation parameters with source mass are visible. These results demonstrate that catalog-level dependence can identify patterns and thus be used to diagnose the origin of deviations in testing general relativity. The framework therefore complements single-event analyses and parameterized hierarchical population tests.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Anisotropic wind in tidal disruption events
Paola Martire, Elena Maria Rossi, Nicholas Chamberlain Stone et al. (+2 more)
Over the coming years, the number of tidal disruption events (TDEs) is expected to substantially increase with observations from the Vera Rubin Observatory (g and r band) and ULTRASAT (near UV) wide-field surveys. These future samples have great promise to characterize the bottom end of the massive black hole mass function, but existing detections of intermediate mass black hole TDEs are primarily in X-rays, leaving their optical/UV emission largely unexplored. We present a time- and angle-dependent analysis of the outflow produced by dissipation near pericentre in a three-dimensional end-to-end radiation-hydrodynamics simulation of a TDE by a $10^4 M_\odot$ black hole with realistic parameters, run with the code RICH. We find that outflow anisotropy produces viewing-angle-dependent observables. Towards the poles and the pericentre region, mass-loss rates are low and bolometric luminosities reach $\sim2$–$3$ times the Eddington luminosity. Towards the stream, the properties show a stronger dependence on latitude: the mass-loss rate increases and the bolometric luminosity decreases as the line of sight approaches the orbital plane. These denser regions favour H$\alpha$ and H$\beta$ emission. Despite these variations, all viewing directions show a common spectral
evolution, with an initial soft X-ray
flare followed (around $1.25t_{\rm fb}\approx3$~days) by the reprocessing of shock-powered emission into the UV and optical bands. Although the optical/UV luminosities we predict for this TDE are likely too dim for past surveys (e.g. ASAS-SN, ZTF), they are within the detection capabilities of LSST and ULTRASAT to horizons of $\sim 790$ and $\sim 340$ Mpc, respectively, for the brightest viewing directions.
Read the full abstract ▾
All authors Paola Martire, Elena Maria Rossi, Nicholas Chamberlain Stone, Elad Steinberg, Itamar Giron
Solar and Stellar Astrophysics
MHD Modelling of magnetic reconnection heating and jets in the solar corona
P. Pagano, C. Argiroffi, F. Reale et al. (+3 more)
Magnetic reconnection is seen as the lead mechanism to explain the persistent and bursty heating of the solar corona that keeps its thermal structure. Lately the observations and modelling of
magnetic reconnection outflows, i.e. nanojets, has empowered our capabilities to scrutinise this mechanisms, however more needs to be understood on the relation between the energetic and kinematic events. The aim of this paper is to study in details the properties of the heating events (nanoflare) and the kinematic counterparts (nanojets) in order to augment detection capabilities of
magnetic reconnection events. We use MHD simulations of the interaction of two
magnetic flux tubes where
magnetic reconnection occurs and such reconnection outflows are generated. We vary key parameters, such as the critical current and the size of the domain to study the heating and slingshot mechanisms. We find that the properties of the nanojets can give away much information on the
magnetic reconnection that generated it, while it is difficult to directly link the amount of heating and the jet speeds. We also find that such reconnection model can explain a wide range of heating events.
Magnetic reconnection still is invariably linked to both heating and outflows and our simulations show the complex interplay between these two byproducts of the
magnetic reconnection and how their properties can be studied in observations.
Read the full abstract ▾
All authors P. Pagano, C. Argiroffi, F. Reale, A. Petralia, G. Cozzo, P. Testa
High Energy Astrophysical Phenomena
The first MeerKAT S-band globular cluster pulsar survey
Rouhin Nag, Marta Burgay, Alessandro Ridolfi et al. (+19 more)
Globular clusters are efficient factories of recycled
pulsars, but searches toward high-dispersion-measure (DM) clusters can be strongly limited near 1 GHz by dispersive smearing and interstellar scattering. We present the first MeerKAT S-band (nu ~ 2.4 GHz)
pulsar survey of 14 globular clusters. High time- and frequency-resolution observations were searched using segmented acceleration and jerk techniques, followed by candidate folding and targeted folding with available timing ephemerides. We re-detected 39 known
pulsars and discovered four new millisecond
pulsars in Glimpse-C01: J1848-0129C, D, E, and F. Multi-epoch follow-up enabled preliminary Keplerian orbital fits for J1848-0129C and J1848-0129D. J1848-0129C is an eclipsing MSP in a ~5 d orbit, placing it among long-period eclipsing systems known as huntsman binaries, while J1848-0129D is in a ~3.4 d nearly circular orbit with a massive white-dwarf companion of about 1 solar mass. Two Glimpse-C01
pulsars show large DM offsets from the cluster average. Comparison with other Galactic globular clusters indicates that intracluster DM spreads tend to increase with foreground DM, implying that narrow DM search windows may be sub-optimal for high-DM clusters. From detections and non-detections, we infer a practical single-epoch MeerKAT S-band tied-array detectability scale of about 10-20 microJy. These results demonstrate the value of high-frequency searches for
pulsars in strongly dispersed and scattered cluster environments.
Read the full abstract ▾
All authors Rouhin Nag, Marta Burgay, Alessandro Ridolfi, Federico Abbate, Andrea Possenti, Paulo C. C. Freire, Scott M. Ransom, Miquel Colom i Bernadich, Michael Kramer, Benjamin W. Stappers, Ewan D. Barr, Rene P. Breton, Vivek Venkatraman Krishnan, Prajwal V. Padmanabh, Weiwei Chen, David J. Champion, Maciej Serylak, Alessandro Corongiu, Mario Cadelano, Vishnu Balakrishnan, Arunima Dutta, Dhanraj Risbud
High Energy Astrophysical Phenomena
Extended gamma-ray emission in the vicinity of the Westerlund 1 massive star cluster and Kes 41 supernova remnant seen by the Fermi Large Area Telescope
L. Tibaldo, R. Bernet, L. Härer et al. (+5 more)
There is growing evidence for
cosmic-ray acceleration in massive stellar clusters. Furthermore, extended gamma-ray emission suggests that particle transport in the vicinity of their sources is influenced by physical processes markedly different from large-scale
diffusion in the Milky Way. We characterize extended gamma-ray emission in the direction of the Westerlund 1 stellar cluster and Kes 41
supernova remnant using > 16 years of data from the Fermi Large Area
Telescope (LAT) at energies > 0.8 GeV. We test whether clusters of gamma-ray sources not associated to multiwavelength counterparts are better described by extended emission components. We report the detection of three new extended emission components with soft spectra towards regions of high gas column density in the Galactic plane. One extended component associated with the natal cloud of Kes 41 is statistically preferred over the point source previously reported towards the
supernova remnant shell. The other two extended components overlap with neutral gas within ~100 pc from the edge of the Westerlund 1 superbubble. The extended emission may be explained either by mismodeled gas in the interstellar background model or by the local injection of particles. Under the latter hypothesis, explaining the component associated with Kes 41 requires converting $\lesssim 5\%$ of the
supernova remnant energy into accelerated particles, while accounting for the two components near Westerlund 1 requires converting $10^{-4}$ of the cluster wind mechanical power into gamma rays. Nevertheless, our results strengthen the evidence for gamma-ray emission structures arising at intermediate spatial scales between isolated objects and the large-scale diffuse emission from the interstellar medium. This could explain a part of the soft unassociated Galactic sources detected by the Fermi LAT. (Abridged)
Read the full abstract ▾
All authors L. Tibaldo, R. Bernet, L. Härer, M. Lemoine-Goumard, L. Mohrmann, G. Peron, B. Reville, T. Vieu
Instrumentation and Methods for Astrophysics · Cross-listed from gr-qc
A Differentiable Parametric Model of Binary-Black-Hole Initial Data: I. Conformally flat Bowen-York punctures
Frederik De Ceuster and Tjonnie G.-F. Li
Constraint-satisfying initial data for binary black holes require the repeated solution of a nonlinear elliptic boundary-value problem throughout the physical parameter space. We present a para\-metric, differentiable initial-data model that combines sparse-grid spectral interpolation with Newton refinement over a family of binary configurations. Interpolation is used only to provide warm starts for the underlying elliptic solver, rather than to replace it. A small number of Newton iterations refines each interpolated solution to a discrete, row-equilibrated constraint residual $\|R\|_\infty\le10^{-10}$, independent of the interpolation error, so that every returned initial-data set satisfies the discretized constraint to that tolerance. Our JAX implementation provides analytic derivatives with respect to the physical parameters, enabling gradient-based parameter targeting, optimization, and sensitivity analysis. We demonstrate the method for quasi-circular binary-black-hole initial data using conformally flat Bowen–York punctures by constructing four-dimensional aligned-
spin and eight-dimensional general-
spin models. The resulting initial data are validated against TwoPunctures, and the method is applied to certified targeting of the physical Arnowitt–Deser–Misner mass and angular momentum and to effective-potential eccentricity reduction using a dedicated separation–tangential-momentum model.
Read the full abstract ▾
Solar and Stellar Astrophysics
Untangling EIT Waves: What a Measured Speed Actually Traces
Olena Podladchikova
Nearly three decades after the first SOHO/EIT observations, reported EUV-wave speeds still range from a few tens to more than 1000 km/s. This Perspective asks what those numbers actually trace. A measured image speed depends on passband and line-of-sight weighting, cadence, difference imaging, the selected crest or leading edge, propagation sector, fitted interval, and projection geometry. Same-event comparisons quantify this observation-operator effect. In events common to the Nitta and Muhr analyses, early or fastest-sector measurements were typically higher; five of six directly shared events differed by about 30%. For 19 May 2007, the 171 Angstrom peak speed was 475 +/- 47 km/s, compared with 238 +/- 20 km/s in 304 Angstrom, while the 171 Angstrom cadence was four times faster than the 195 Angstrom cadence. A sampling audit of the 1 April 2017 SWAP event shows that a repeated speed near 834 km/s is almost exactly one 91.6-Mm radial ring per 110-s image interval. In a reconstructed 3 April sector, AIA 171 Angstrom gives about 405 km/s, compared with the published SWAP mean of 484 km/s; an independently selected AIA 193 Angstrom ridge gives about 250 km/s under strongly shortened exposures. Such differences are not automatic evidence for different MHD modes. A same-event energy pilot separates compact-source heating, dimming/ejecta, and one weak-compression front segment. The current data do not justify a universal power law, but define a falsifiable question: is the fraction of released energy carried by the front scale invariant from compact quiet-Sun events to global waves and shocks? Establishing this dependence would show which eruption scales can contribute materially to coronal heating.
Read the full abstract ▾
Astrophysics of Galaxies
The internal kinematics and chemistry of 20 Milky Way strings
C. Boeche, A. Vallenari, J. Alonso-Santiago et al. (+8 more)
Context: the recent discovery of filamentary stellar structures in the Milky Way disk raises the question of their formation in the context of the
Galaxy evolution. Aims: in this work, we aim to kinematically and chemically characterize several filamentary stellar structures by looking for clues about their origin and formation mechanism. Methods: recent works using machine-learning techniques and $Gaia$ data have identified many previously unknown Galactic strings. We cross-matched such data with the kinematics derived from the most recent Gaia DR3 catalog as well as chemical data provided by the Galactic Archaeology with HERMES (GALAH) survey. Results: we found that most strings contain one or more open clusters and are kinematically hotter than open clusters (with internal velocity dispersions in the 1–7 km/s range) but cooler than field
stars. 18 objects appear chemically homogeneous ($\sigma_{[Fe/H]}$ <= 0.1 dex), while two strings have a broad [Fe/H] distribution similar to the field
stars but exhibit a different mean
metallicity, which may identify them as migrating stellar structures. For seven objects the GALAH observations focus on the embedded open clusters; therefore, the chemical abundances are not representative of the whole structure. An object shows clues of chemical gradients along its extension in Galactic longitude. Conclusions: these objects may be evaporating or disrupted open clusters in which the chemical homogeneity is preserved in an unbound and expanding cloud of
stars or co-moving
stars belonging to a former and now disrupting
star formation hub. In a few cases they appear to be moving groups with no chemical homogeneity, likely formed by the dynamical action of the Galactic bar or spiral arms. More data are needed to confirm such hypotheses.
Read the full abstract ▾
All authors C. Boeche, A. Vallenari, J. Alonso-Santiago, A. Bragaglia, R. Carrera, E. Dalessandro, E. Carretta, E. Franciosini, A. Frasca, S. Lucatello, G. Andreuzzi
Instrumentation and Methods for Astrophysics · Cross-listed from physics.ins-det
Post-fabrication trimming of a 1024-pixel, single-photon counting, Microwave Kinetic Inductance Detector array with a pixel pitch of 150 micron
Wilbert Ras-Vinke, Hessel Schulte, David J. Thoen et al. (+5 more)
Microwave Kinetic Inductance Detectors are superconducting resonators capable of single-
photon counting with energy resolving capability at visible and near-infrared wavelengths. Their zero read noise, extremely low dark counts, and compatibility with frequency-division multiplexing make them well suited for large imaging arrays. The detector yield of these arrays is often limited by the fabrication-induced frequency scatter leading to resonator collisions. We find that the tight packing of the pixels can add significant frequency scatter as well. We developed a post-fabrication correction method that is suitable for tightly packed arrays with a pixel pitch of $150\ \mathrm{\mu m}$. We demonstrate this method on a 1024-pixel array multiplexed on a single octave of readout bandwidth and show a reduction in frequency scatter from $1.1\times 10^{-2}$ to $3.5\times 10^{-4}$ and an increase in yield from $76\%$ to $94\%$.
Read the full abstract ▾
All authors Wilbert Ras-Vinke, Hessel Schulte, David J. Thoen, Kevin Kouwenhoven, Steven A.H. de Rooij, Tonny A.H.M. Coppens, Jochem J.A. Baselmans, Pieter J. de Visser
Cosmology and Nongalactic Astrophysics
Observational constraints on a damped harmonic oscillator model of dark energy
Saddam Hussain, Muhammad Ahmad, Ming Zhang et al. (+2 more)
We constrain a damped harmonic oscillator (DHO) dark-energy equation of state using the full
cosmic microwave background (CMB) likelihoods in combination with DESI BAO and three distinct Type Ia
supernova compilations: Pantheon+, DES-Dovekie, and Union3. The equation of state obeys a second-order damped oscillator equation in number of $e$-folds, so that its frequency $f$, damping rate $b$, and
equilibrium value $w_{\rm m}$ fully specify the late-time dynamics. The model exhibits oscillatory behavior only at low
redshifts, around the
equilibrium value $w=-1$, with distinct characteristics for the different
supernova compilations: an underdamped solution for DES-Dovekie and Union3, and an overdamped solution for Pantheon+. At higher
redshifts, the model closely mimics $\Lambda$CDM and deviates significantly only at $z<0.6$, with the magnitude of the deviation depending on the
supernova compilation. We further identify a region of the $(f,b)$ parameter space, corresponding to rapid variation of the equation of state at low
redshift, in which the perturbation equations become numerically stiff and cannot be integrated with a canonical dark-energy sound speed i.e., $c_s^2 =1$. We show that reducing the rest-frame sound speed removes this obstruction while leaving the observables unchanged at the $10^{-3}$ level, and therefore treat it as a numerical prescription rather than a physical modification of the model. The model yields $H_0 = 67.53^{+1.22}_{-1.18}$ km/s/Mpc for Pantheon+, $H_0 = 69.08^{+1.23}_{-1.16}$ km/s/Mpc for DES-Dovekie, and $H_0 = 70.67^{+1.89}_{-1.87}$ km/s/Mpc for Union3. The present-day equation-of-state parameter is constrained to $w_0 = -0.521^{+0.891}_{-0.414}$, $-3.01^{+1.14}_{-1.21}$, and $-3.16^{+1.11}_{-1.16}$ for Pantheon+, DES-Dovekie, and Union3, respectively.
Read the full abstract ▾
All authors Saddam Hussain, Muhammad Ahmad, Ming Zhang, Ayodeji Ibitoye, Lang Cui
Cosmology and Nongalactic Astrophysics
Safe Phantom Divide Crossing from Unscreened Non-Minimal Coupling to Gravity
Joel Argudo-Panes, Alex González-Fuentes and Adrià Gómez-Valent
Recent hints of dynamical dark energy, including a possible crossing of the phantom divide, have motivated the search for viable theoretical explanations. Scalar fields non-minimally coupled to
gravity with a coupling of the form $F(\varphi)=1+\alpha\varphi^2$ have emerged as promising candidates, providing an improved fit to the data compared to $\Lambda$CDM and even the $w_0w_a$CDM parametrization. However, in the absence of a screening mechanism, the regions of parameter space examined exhaustively so far (with $\alpha<0$) violate stringent local constraints on the strength and time variation of
gravity and enhance the matter growth rate at low
redshifts, thereby compromising the viability of these solutions. In this work, we investigate a largely unexplored region of parameter space (with $\alpha>0$) that realizes the crossing while remaining consistent with local constraints. This setup, which is subject to some fine-tuning, respects the BBN constraints and leads only to deviations of the effective gravitational coupling from Newton's constant below $0.3%$ in the past. We review the background and linear perturbation dynamics of the model, deriving analytical results that provide physical insight into its behavior, and update the constraints on the model using the latest cosmological data, including the DES-Dovekie
supernova sample. We perform for the first time a full-fledged Monte Carlo analysis with $\alpha>0$, studying the impact of the variation of $G$ on the
supernovae absolute luminosity, and compare the results with those obtained for $\alpha<0$, using in both cases a linear potential. In the context of the model with non-minimal coupling and $\alpha<0$, the standard model is excluded at the $2.50\sigma$ CL, whereas for $\alpha>0$, the exclusion significance decreases to $\sim 2\sigma$ CL, indicating a moderate preference for these models over $\Lambda$CDM. [abridged]
Read the full abstract ▾
High Energy Astrophysical Phenomena
Hadronic origin of gamma rays and neutrinos from blazars: Multi-messenger implications and observational constraints
Rodrigo Sasse and Rita de Cássia dos Anjos
We investigate whether cosmogenic gamma rays and
neutrinos from ultra-high-energy
cosmic rays (UHECRs) produced in hadronically active blazars can significantly contribute to the observed spectral energy distribution (SED), and examine the potential of the Cherenkov
Telescope Array Observatory (CTAO) to detect and discriminate this component. For four nearest
neutrino bright blazars modeled by Rodrigues (2024), specifically AP Librae, TXS 1700+685, PKS 2326$-$502, and PKS 2345$-$16, we constrain the UHECR luminosity by requiring that the total emission does not overshoot available multi-wavelength data, assuming acceleration in the optically thin large scale jet, propagate UHECRs through realistic Galactic and extragalactic
magnetic fields, and forecast CTAO performance. We find that cosmogenic gamma rays contribute up to about 7.5% of the total gamma-ray emission at the highest energies ($10^{20}$ eV), and thus remain subdominant in the SED. In contrast, the associated
neutrino emission, at approximately $10^{44}$ to $10^{46}$ erg s$^{-1}$, offers a robust propagation signature of hadronic acceleration. Our simulations of 50 hour CTAO exposures show that the observatory can accurately reconstruct the intrinsic gamma ray spectrum, enabling strong constraints on the hadronic origin and propagation of UHECRs. These results demonstrate the power of combining CTAO gamma-ray measurements with
neutrino observations to probe blazar hadronic processes.
Read the full abstract ▾
Instrumentation and Methods for Astrophysics · Cross-listed from quant-ph
Multiparameter quantum bounds for entanglement-assisted aperture synthesis
Kalaga Madhav, Pieter Kok and Nic Scott
Entanglement-assisted optical interferometry promises diffraction-limited imaging over baselines where light cannot be physically combined, but existing theory treats only a single visibility on one two-station baseline. This work formulates the multiparameter estimation problem for an M-station array imaging an extended scene. A reduction lemma shows that the multimode
quantum Fisher information (QFI) equals the mean
photon number times the QFI of a single delocalized
photon, collapsing the problem to a finite-dimensional one. The local
photon-number superselection rule (SSR) erases all phase information from the bare state, while shared
entanglement restores a fraction f(r)=r/(1+r) of the QFI on a baseline supplied with r pairs – a factor shown to be achievable, since the reduced two-mode state of any pair is exactly the two-station weak-thermal state. The QFI
matrix and its mean Uhlmann
curvature reveal numerically that a point source is measurement-compatible, whereas for every extended-source model examined it is incompatible, the Holevo bound exceeding the symmetric-logarithmic-derivative (SLD) bound by up to ~74%. An explicit collective receiver – a global mode-sorting (
quantum Fourier transform) measurement – then attains a weighted variance within ~7% of the SLD bound and roughly an order of magnitude below an explicit pairwise receiver, and a noisy-resource advantage threshold gives the break-even baseline (~20 km for near-term parameters) beyond which repeater-distributed
entanglement beats direct transmission. Finally, the optimal allocation of a finite
entanglement budget is a convex program with a closed-form proportional (square-root-law) solution favoring low-visibility baselines. These results recast
quantum aperture synthesis as collective multiparameter estimation and give concrete design targets, illustrated on the CHARA array.
Read the full abstract ▾
Instrumentation and Methods for Astrophysics
Enabling New Discoveries with Machine Learning
Michelle Lochner
The next generation of
telescopes such as the Square Kilometre Array and the Vera C. Rubin Observatory will produce enormous quantities of data, too large for traditional analysis techniques. Machine learning has proven invaluable in handling massive data volumes and automating tasks traditionally done by human scientists. The question is, can machine learning also automate scientific discovery? Recent advances in the field have made this feasible but only when combined with expert human input through active learning. Astronomaly is a publicly available framework for active anomaly detection in astronomy. It learns to make recommendations of interesting sources to a user, allowing scientists to quickly uncover rare and new classes of objects in large
datasets. In this paper, we review some of the discoveries made using Astronomaly, discuss the latest deep learning-based approaches and explore the critical role of the cyber-human interface in unveiling
cosmic mysteries hidden in massive astronomical
datasets.
Read the full abstract ▾
Astrophysics of Galaxies
The JWST Emission Line Survey (JELS): Multi-wavelength properties of Paschen line-emitters at Cosmic Noon
Malte Brinch, Edo Ibar, Luis Ossa-Fuentes et al. (+14 more)
Context: Narrowband JWST/NIRCam selection isolates
star-forming
galaxies in well-defined
redshift slices, while ALMA and archival far-IR/submm data reveal obscured growth. We combine these to measure Paschen-line SFRs, infer nebular extinction from EAZY Av, and probe FIR-to-submm emission via weighted-median stacking, to constrain
galaxy growth at
cosmic noon. Aims: We characterize stellar, nebular, and FIR properties of Paschen-selected
galaxies in COSMOS, in two ensembles at z~1.50 (Pa-alpha) and z~2.65 (Pa-beta), quantifying short- vs long-timescale SF and dust attenuation, and constraining obscured SFR and gas masses. Methods: We select robust narrowband-excess samples from the JELS F466N/F470N mosaic (Pa-alpha: 77, Pa-beta: 31 sources), remove AGN via X-ray/
radio matching, and assemble multiwavelength photometry (JWST, HST, Spitzer, Herschel, SCUBA-2, AzTEC, ALMA). Photo-z/stellar properties come from EAZY/STARDUST; line SFRs use recent Paschen calibrations, with nebular extinction from EAZY Av. Results: EAZY fits show stellar masses log(Mstar/Msun)~7.4-10.3 and modest SFRs (0.1-27 Msun/yr). Line SFRs are 0.1-22.0 and 0.7-47.9 Msun/yr for Pa-alpha/beta. Most sources show short-term bursts (line SFRs exceed SED SFRs), weakly decreasing with mass. Nebular attenuation correlates with mass and SFR. Stacking gives no >3sigma detections beyond MIRI. The weighted-median SED gives SFR_UV,med = 0.48+-0.11 and 3.92+-0.47 Msun/yr for Pa-alpha/beta. ALMA Band 4 gives the tightest constraints: median 3-sigma limits SFR_IR<53 (Pa-alpha) and <44 Msun/yr (Pa-beta); gas mass <10^11.2 (Pa-alpha) and <10^10.6 Msun (Pa-beta). Conclusions: Paschen-selected samples show widespread short-timescale
star formation, but FIR/sub-mm data give only upper limits on obscured SFR/ISM mass. Deeper spectroscopy and ALMA continuum data are needed to constrain obscured SF and gas reservoirs.
Read the full abstract ▾
All authors Malte Brinch, Edo Ibar, Luis Ossa-Fuentes, Corey Pirie, Philip Best, R. K. Cochrane, Kenneth Duncan, James Dunlop, Sophia Flury, Catherine Hale, Jorryt Matthee, Derek McLeod, Joshua Selfridge, David Sobral, Harry Stephenson, J. P. Stott, A.M. Swinbank
High Energy Astrophysical Phenomena
Search for refractive substructure in active galactic nuclei using ground-based VLBI observations
Tatiana A. Koryukova, Alexander V. Plavin, Alexander B. Pushkarev et al. (+1 more)
We present the results of the first systematic search for refractive scattering substructure in active galactic
nuclei (AGN) using ground-based very long baseline interferometry (VLBI) data. We selected 1074 AGNs showing a steep frequency dependence of their angular sizes and compared the observed long-baseline visibility amplitudes with the predictions of the refractive substructure model for scatter-broadened images. Nine sources showed consistency with the expected level of refractive noise, including the
quasar TXS 2005+403 (J2007+4029), which confirms previously reported results for this source. Remarkably, the majority of these AGNs are located in the Cygnus region – one of the key “hotspots” of strong Galactic scattering. For five selected AGNs, we identified at least two epochs with sufficiently high data quality showing long-baseline detections, suggesting the presence of scattering substructure. We showed that refractive scattering substructure in AGN is a rare effect, requiring high sensitivity, sufficient source brightness, and lines of sight with particularly strong
turbulence in the interstellar medium. Nevertheless, AGNs can serve as powerful probes of the turbulent interstellar medium. We discuss strategies for improving the sensitivity of VLBI observations and identify the most promising sources for reliable detection and investigation of refractive substructure in future observations.
Read the full abstract ▾
All authors Tatiana A. Koryukova, Alexander V. Plavin, Alexander B. Pushkarev, Yuri Y. Kovalev
Earth and Planetary Astrophysics
Physics-Informed Multi-Task Surrogate Model for the Martian Nightside Thermosphere
Sergey Nikiforov
Modeling the Martian nightside thermosphere remains challenging due to sparse in situ sampling and strong coupling among transport,
magnetic, and seasonal processes. Purely data-driven models can produce non-physical artifacts, such as density inversions, in poorly sampled altitude regimes. We present a multi-task physics-informed neural network that simultaneously predicts the base-10 logarithmic densities of four neutral species (O, CO$_2$, N$_2$, and Ar) using more than a decade of MAVEN/NGIMS observations (MY 32-38, 2014-2025). A shared backbone learns a common representation of the nightside thermospheric state and branches into species-specific output heads. A weak monotonicity prior is incorporated via automatic differentiation by penalizing positive vertical gradients in logarithmic density. Experiments using an orbit-disjoint train/validation/test split show that physics-informed regularization substantially reduces non-physical inversions while preserving predictive skill and slightly improving it in the best-performing configuration, as measured by RMSE, MAE, and $R^2$. The resulting model provides a computationally efficient surrogate for nightside thermospheric reconstruction with improved vertical consistency.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Orthogonal polarization modes of nonbirefringent origin in a geometric radio pulsar signal model
J. Dyks, L. Saha and A. Frankowski
Motion of
plasma in
pulsar magnetospheres essentially follows bent
magnetic field lines which may result in radiation beams sweeping past the observer's sightline. We show that under certain conditions such a passing beamlet can produce two orthogonal polarization modes (OPMs) solely from averaging of radiative contributions, without involving birefringence. This requires that radiation from different stages of the passage is contributed incoherently, hence that the timescale for the coherence is much shorter than the typical sampling time. The model produces two OPMs of comparable amount, with a wide range of (single-pulse) polarized fractions, which is consistent with general observed
pulsar properties. Under the specific conditions required (essentially incoherent summation of signal at appropriate time scale) the averaging effects alone can thus lead to the appearance of two orthogonal polarization tracks with OPM jumps.
Read the full abstract ▾
Instrumentation and Methods for Astrophysics
Modelling Fourier filtering wavefront sensors for PSD-based methods: the AOPERA tool
Romain Fétick, Vincent Chambouleyron, Lisa-Marie Mazzolo et al. (+6 more)
Compensation of the atmospheric
turbulence thanks to adaptive optics (AO) has now become commonly used for VLT or ELT class
telescopes in order to retrieve a resolution close to their diffraction limit. Following the increasing trend of AO system, there is also a stronger necessity for simulations in order to understand and predict their performance facing different observing conditions, that are the
evolution of the atmospheric
turbulence or the diversity of AO guide source. The so-called PSD based methods are well adapted to the demand thanks to their simplicity and speed. Moreover, they provide a comprehensive breakdown error budget and impact on focal plane, that is of high interest especially in the case of extreme adaptive optics. Their drawback is the challenge to describe non-linear wavefront sensors (WFS) such as the pyramid WFS or the Zernike WFS. There is a necessity to develop fast yet accurate methods to describe the behaviour of AO systems including sensitive WFS. We thus develop a method to compute the AO system response (electromagnetic phase power spectral density, and point spread function) including the non-linear behaviour of the wavefront sensor within PSD-based numerical tools. Mathematical formalism to describe the FF-WFS sensitivity combined to non-linearity management greatly improve the accuracy of description of AO systems through numerical simulations. After a mathematical description of the method, its numerical implementation is compared with end-to-end simulations using the OOPAO tool. Indeed end-to-end simulations are reproducing the response of AO systems with high fidelity, especially regarding WFS sensitivity and non-linearity. Similarity of results for the fitting error, temporal error and noise error proves the validity of our method in managing
Fourier filtering WFS sensitivity and non-linearity.
Read the full abstract ▾
All authors Romain Fétick, Vincent Chambouleyron, Lisa-Marie Mazzolo, Christophe Vérinaud, Arnaud Striffling, Cédric Héritier-Salama, Benoit Neichel, Jean-Francois Sauvage, Thierry Fusco
High Energy Astrophysical Phenomena
Evidence of a Low-Energy Cutoff in the Injected Spectrum of a Pulsar Wind Nebula
Zhihong Shi, C.-Y. Ng, Niccol`o Bucciantini et al. (+5 more)
Bow-shock
pulsar wind nebulae (PWNe) are synchrotron sources formed when the outflow of supersonic
pulsars is confined by the surrounding interstellar medium. These sources are dominated by freshly injected particles, thus providing a unique laboratory for studying particle acceleration in relativistic outflows. The Mouse is a prototypical bow-shock PWN and is bright in the
radio and X-ray bands, enabling detailed multi-wavelength spectral modeling. With data from 17
telescopes, the Mouse is detected from 118 MHz to 353 GHz, covering over 3 decades in frequency, and in X-rays from 0.5 to 30 keV. A clear spectral break is identified at 3.7 GHz. The
radio spectrum exhibits a rising trend at low frequency, peaks at the break, and then declines. We find a change in spectral index $\Delta\alpha=0.65\pm0.05$ across the break. We attribute this to an intrinsic cutoff or steepening in the injected particle distribution. This could indicate the characteristic energy of leptons leaving the
pulsar magnetosphere, or energy dissipation after the particles cross the termination shock.
Read the full abstract ▾
All authors Zhihong Shi, C.-Y. Ng, Niccol`o Bucciantini, B. M. Gaensler, Zhen Yan, David J. Wilner, Douglas C.-J. Bock, Hua-bai Li
Earth and Planetary Astrophysics
Magnetically Driven Obliquity in Circumplanetary Disks and Twisted Bipolar-jet Formation
Raúl O. Chametla, Martin E. Pessah, F. Javier Sánchez-Salcedo et al. (+4 more)
Circumplanetary disks (CPDs) regulate gas
accretion onto forming giant
planets and provide the environment in which their satellites may form. We use high-resolution, global three-dimensional simulations to investigate the early formation, orientation, and outflows of a CPD around a Jupiter-mass
planet embedded in a turbulent magnetized protoplanetary disk. Within a locally isothermal, ideal-MHD framework, we evolve disks threaded by net vertical
magnetic fields, corresponding to initial
plasma parameters $875\leq\beta\leq3500$, until magnetorotational-instability-driven
turbulence is established before inserting the
planet. We also perform a hydrodynamic control simulation. In the most strongly magnetized model, with $\beta=875$, the CPD forms already highly inclined and reaches a maximum tilt of approximately $87^\circ$. By contrast, the hydrodynamic CPD and the MHD models with $\beta\gtrsim1000$ remain nearly coplanar. A control simulation in which the
planet is inserted before global MRI
turbulence develops also remains coplanar, despite producing local
turbulence and bipolar outflows. The large tilt is therefore associated with the pre-existing global turbulent state and its evolved velocity and toroidal
magnetic-field structure, although our current diagnostics do not distinguish between a direct
magnetic torque and the
accretion of misaligned angular momentum. All MHD models launch bipolar outflows; in the highly tilted case, these develop a curved, helical morphology that persists until the end of our short-term simulations. These results identify pre-existing global magnetized
turbulence as a viable route to generating strongly inclined CPDs and twisted planetary outflows.
Read the full abstract ▾
All authors Raúl O. Chametla, Martin E. Pessah, F. Javier Sánchez-Salcedo, David Vokrouhlický, Mauricio Reyes-Ruiz, Ondrej Chrenko, Alessandro Morbidelli
Earth and Planetary Astrophysics
Can the Long-Term Impact of Stellar M-Dwarf Flares Alter the Spectral Features of a Giant Gaseous Exoplanet?
Amy Louca, Shang-Min Tsai and Yamila Miguel
In this work, we model the long-term impact of recurrent stellar
flares on the atmospheres of metal-rich gaseous
exoplanets. Using synthetic
flare spectra from a fiducial
flare model integrated with a photochemical kinetics code, we track the changes in atmospheric composition with time. We further analyze the spectral variability by feeding these abundance profiles into a radiative transfer code at various time steps. Our simulations showed variability and persistent changes in key atmospheric species, such as CH4, CO2, and SO2, when compared to their quiescent state. Extreme
flare events cause rapid depletion of molecules in the upper atmosphere and a temporary disappearance of spectral features, especially the SO2 feature at 7-8 microns, which shifted by about 75 ppm. Many species did not fully return to their quiescent state after
flares, resulting in lasting changes in abundance, especially for SO2 and CO2, key species when inferring the atmospheric metallicty. We also explored the cumulative effects of recurrent
flares, showing that species like H2O and CH4 followed a decreasing abundance trend, with half-lives of around 28 to 31 years. These results indicate that
flare activity plays a significant role in shaping both the short- and long-term atmospheric composition and spectral features of giant gaseous
exoplanets orbiting M-dwarf
stars, underscoring the need to account for stellar activity when characterising such atmospheres. Our findings also highlight that the atmosphere of the modelled
planet is not static, suggesting that a probabilistic approach to atmospheric abundances may be more appropriate than static
retrievals, particularly for gaseous
planets orbiting active
stars.
Read the full abstract ▾
Astrophysics of Galaxies
Milky Way Structure from Double White Dwarf Gravitational-Wave Sources
Shao-Dong Zhao, Xue-Hao Zhang, Qun-Ying Xie et al. (+2 more)
The millihertz gravitational-wave sky will be dominated by $\sim10^{8}$ double white dwarfs while $\sim10^{4}$ be resolvable in the Milky Way, whose three-dimensional spatial distribution traces the
Galaxy's structural parameters. We present Galena, a hierarchical
Bayesian pipeline that recovers these parameters from a double white dwarf catalogue through an inhomogeneous Poisson-process likelihood. Each source's $3\times3$ Galactic position covariance is computed from the waveform Fisher information
matrix and propagated analytically through a $3\times5$ Jacobian; the resulting measurement-error convolution is factored into a pre-computed sparse weight
matrix, rendering the nested-sampling inference tractable. Applied to GBSIEVER-reported LISA Data Challenge sources ($N=2151$ after quality cuts), Galena recovers the disk scale length $R_d=2175^{+51}_{-52}$~pc and scale height $z_d=282^{+7}_{-7}$~pc, consistent with a canonical thin disk, together with the bulge fraction $A=0.187^{+0.011}_{-0.012}$ and bulge scale radius $R_b=773^{+26}_{-25}$~pc; the bulge fraction, now recovered much closer to the literature value of $0.25$ than in our earlier exact-position fit, is measured at $\sim6\%$ statistical precision. An independent particle-swarm optimisation of the same likelihood reproduces these values to within a fraction of a percent, supporting the attribution of the improvement to the Fisher-
matrix error propagation rather than to the sampler. The search-stage astrophysical prior improves per-source distance estimates but leaves the hierarchical inference essentially unchanged.
Read the full abstract ▾
All authors Shao-Dong Zhao, Xue-Hao Zhang, Qun-Ying Xie, Yu-Xiao Liu, Soumya D. Mohanty
Cosmology and Nongalactic Astrophysics
Learning cosmic web environments with diffusion models
Mehdi Noor, Tony Bonnaire, Nabila Aghanim et al. (+1 more)
The
cosmic web, consisting of an intricate network of voids, walls, filaments, and nodes, encodes key information about structure formation and the cosmological parameters that govern it. In the era of high-precision cosmology, large ensembles of numerical simulations are required to analyse next-generation
galaxy surveys, motivating the use of generative models to circumvent their high computational cost. While they have shown promise in emulating high-fidelity
cosmic web simulations, their ability to capture distinct
cosmic web environments remains largely unexplored. For this study, we trained a
diffusion model on the Quijote N-body simulation suite to investigate the semantic information learnt by its self-
attention maps. Using statistical
estimators such as the Dice coefficient and cross-power spectra, we quantified the correspondence between
attention maps and
cosmic web environments defined by the T-Web classifier. We find that
attention maps of varying spatial resolutions across different layers capture overdense and underdense structures in distinct ways, exhibiting strong positive correlations and anti-correlations with both the overall matter distribution and individual
cosmic web environments. Moreover, the
diffusion model predominantly encodes cosmological information at intermediate-to-large spatial scales, indicating that
attention maps primarily capture globally coherent structures. Our results show that, beyond accurately reproducing two-point statistics,
diffusion models learn a multi-scale representation of the
cosmic web through self-
attention, including non-Gaussian information.
Read the full abstract ▾
All authors Mehdi Noor, Tony Bonnaire, Nabila Aghanim, Aurélien Decelle
Solar and Stellar Astrophysics
Long-slit spectroscopy of the bipolar planetary nebula ESO\,428$-$05
Alexei Kniazev
The results of detailed long-slit spectroscopy of the bipolar planetary nebula \ESO\ are presented. The observations were obtained with the facility spectrograph RSS of the SALT
telescope. The total measured extent of the nebula reaches $\approx$55$^{\prime\prime}$, and the kinematics along the slit directly confirms its bipolar structure. The inclination of the nebula to the line of sight is estimated as $i\approx 45^{\circ}$, and the kinematic ages of two morphological structures are measured: the expanding ring and the polar outflow in the direction perpendicular to the ring. The age of the former is $\approx$1.5$\times$10$^4$~yr and that of the latter is $\approx$(3–4)$\times$10$^4$~yr, i.e. the polar outflow is 2–3 times older than the central ring. The ratio of these ages does not depend on the adopted distance. The weighted mean heliocentric velocity of \ESO\ is V$_{\rm hel}$=74.7$\pm$1.6~\kms. Chemical abundances are obtained for 19 regions along the major axis of the nebula, over an extent of 40$^{\prime\prime}$, i.e. for different morphological parts of \ESO. The abundances were derived with the T$_{\rm e}$–method, where the electron temperature was calculated directly using the measured faint auroral lines [\ion{O}{iii}]~$\lambda$4363~Å\ and [\ion{N}{ii}]~$\lambda$5755~Å. The abundances of O, N, Ne, S, Ar, Cl and He were determined. Despite a significant stratification, the measured abundances along the slit can be considered nearly constant.
Read the full abstract ▾
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Prospects of electromagnetic follow-up of neutron star-black hole mergers in the LIGO-India era
Yogita Kumari, Kanchan Soni and Sanjit Mitra
Neutron star-black hole (NSBH) mergers are promising multimessenger sources, but only a subset is expected to produce detectable electromagnetic (EM) counterparts, depending on the binary mass ratio, black hole (BH)
spin, and
neutron star (NS) equation of state (EoS). We investigate the prospects for detecting kilonova counterparts to NSBH mergers in the LIGO-India era using the Vera C. Rubin Observatory (Rubin). We simulate GW230529-motivated NSBH populations with two effective tidal deformability ranges, estimate gravitational-wave detections for the LHV (LIGO-Livingston, LIGO-Hanford, Virgo) and LHVA (LHV with LIGO-India at Aundha) detector networks, and model the detectability of the associated kilonova emission with Rubin. We find that adding LIGO-India approximately doubles the number of EM follow-ups, primarily by increasing the duty cycle and reducing the median sky-localization area, and notably increases the number of such detections at large distances. For fixed-exposure strategies, the EM detection rate saturates at exposure times of a few hundred seconds, reflecting the trade-off between depth and sky coverage. We therefore introduce an event-specific exposure-time optimization strategy based on the expected counterpart brightness and sky-localization area. With this strategy, the expected NSBH GW+EM detection rate per year is 4.19(-3.58,+9.66) for the optimistic and 0.79(-0.68,+1.83) for the conservative population with the LHVA network, compared to 1.46(-1.25,+3.37) and 0.27(-0.23,+0.62), respectively, for LHV. The required Rubin follow-up time remains within the expected Target-of-Opportunity allocation. These results show that in the next decade, a few such NSBH follow-ups may take place, with a fraction of them in the
redshift range of about 0.1-0.2, which will not only be useful for measuring the Hubble constant but can also help us in probing the Hubble parameter.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Time-Correlated Profile Variability in the MeerKAT Pulsar Timing Array
Bhavnesh Bhat, Michael J. Keith, E. Carli et al. (+2 more)
Long-term pulse-profile variability has emerged as a potentially important source of uncertainty for high-precision
pulsar timing, as changes in the integrated pulse shape can bias pulse times of arrival and affect the sensitivity of
pulsar timing arrays to nanohertz gravitational waves. We present a systematic search for long-term pulse-profile variability in the six-year MeerKAT
Pulsar Timing Array data, analysing observations of 84 millisecond
pulsars using a two-dimensional Gaussian-process framework to identify coherent temporal and phase-dependent profile
evolution. We detect pulse-profile variability in 18
pulsars. Using the frequency dependence of the observed profile
evolution together with scattering simulations, we classify six
pulsars as exhibiting chromatic variability consistent with interstellar scattering, while the remaining twelve display predominantly frequency-independent behaviour suggestive of intrinsic changes in the
pulsar emission process. Correcting for the S/N-dependent detection bias, we infer that intrinsic profile variability is substantially more common than implied by the detected sample, with at least 40 per cent of millisecond
pulsars exhibiting intrinsic profile variability at the 95 per cent credible level. Motivated by the association between pulse-profile variability and
spin-down-rate ($\dot{\nu}$) switching in canonical
pulsars, we search for corresponding $\dot{\nu}$ variations but find no statistically significant detections. Simulations indicate that the expected variations remain below the sensitivity of current
datasets, although unresolved changes may contribute to weak achromatic timing noise. These results suggest that long-term pulse-profile variability may be common among millisecond
pulsars and should be explicitly modelled in future high-precision
pulsar-timing experiments.
Read the full abstract ▾
All authors Bhavnesh Bhat, Michael J. Keith, E. Carli, R. M. Shannon, Benjamin W. Stappers
Astrophysics of Galaxies
The magnetic field in M16: new results from the JCMT BISTRO survey
R.M.R. Tulloh, D. Ward-Thompson, J. Karoly et al. (+2 more)
We present a study of the
magnetic field (B-field) in the Eagle Nebula (M16) using data from the James Clerk Maxwell
Telescope (JCMT) B-fields In
STar-forming Region Observations (BISTRO) survey. We extend our previous study of the well-known `Pillars of Creation' region of the nebula to study two other structures in the region, the `Spire' and the bright-rimmed cloud (BRC) known as `SFO30'. These structures show similar B-field morphologies to the Pillars. We calculate B-field strengths using the Davis-Chandrasekhar-Fermi (DCF) method and thereby estimate the
magnetic potential energy in each of these regions for comparison with the local gravitational, turbulent and thermal energies, as well as the pressure energy of the shocks from nearby O-type
stars. We find approximate equipartition between the energies supporting the regions and those tending towards collapse, with the B-field support playing a significant role. This agrees with our earlier hypothesis that B-fields help support pillar-like structures in molecular clouds and make them longer-lived than they would otherwise have been.
Read the full abstract ▾
All authors R.M.R. Tulloh, D. Ward-Thompson, J. Karoly, J.M. Kirk, K. Pattle
Astrophysics of Galaxies
The Dense Gas Structures Around MMS 2/OMC-3 Traced by C$^{18}$O Emission
Yuhua Liu, Satoko Takahashi and Masahiro N. Machida
We report the Atacama Large Millimeter/submillimeter Array observations of 1.3 mm continuum, C$^{18}$O ($J=2$$-$$1$), and N$_{2}$D$^{+}$ ($J=3$$-$$2$) toward the millimeter multi-system MMS 2 in the Orion Molecular Cloud-3 region, at an angular resolution of 1.59" ($\sim$620 au). MMS 2 is in the flat-spectrum phase, with its protostars in the late stage of the main
accretion phase. We detect the centrally condensed structures traced by C$^{18}$O emission associated with the 1.3 mm continuum sources MMS 2-North and MMS 2-South, which are spatially resolved and unresolved, respectively. The estimated diameter and mass of the centrally condensed structure associated with MMS 2-North are 1.64" ($\sim$640 au) and 3.0$\times$10$^{-4}$M$_{\odot}$, respectively. We also detect an extended structure traced by C$^{18}$O emission associated the circumbinary envelope at scale of 5.70" ($\sim$2240 au) with an estimated gas mass of 1.4$\times$10$^{-2}$$M_{\odot}$. In addition, we detect a filamentary structure traced by N$_2$D$^+$ emission to the south of MMS 2, which is spatially offset from the C$^{18}$O emission. This offset may be attributed to the influence of the warm surrounding environment.
Read the full abstract ▾
Earth and Planetary Astrophysics
JWST-SUPER I: New insights into irradiated warm Neptunes atmospheres from MIRI observations of HD 106315 c
A. Dyrek, R. Waters, S.-M. Tsai et al. (+17 more)
Sulphur-bearing molecules have recently emerged as powerful tracers of atmospheric photochemistry in
exoplanets observed with JWST. In several warm giant
planets, SO$_2$ has been detected as a product of UV-driven chemical processing, suggesting a close connection between stellar irradiation, atmospheric
metallicity, and sulphur chemistry. Whether these trends extend to Neptune-mass
planets orbiting hotter
stars remains largely unexplored. We investigate the atmospheric composition of the warm Neptune HD 106315 c, a Neptune-mass
planet orbiting an F-type host
star and subjected to a strong ultraviolet (UV) irradiation environment. Here, we report the low-resolution transmission spectrum between 5 and 12 $\mu$m of HD 106315 c obtained with the MIRI Low-Resolution Spectrometer on-board JWST. Our work also includes re-analysis of archival data from HST WFC3 G141 mode of HD 106315 c, as well as contemporaneous XMM and Swift monitoring of the
star in the UV and X-ray wavelength ranges. Together with the archival HST WFC3 data, we detect H$_2$O and find tentative evidence for NH$_3$, retrieving abundances of $\log_{10}$(H$_2$O)$=-1.40^{+0.40}_{-0.74}$ and $\log_{10}$(NH$_3$)$=-2.47^{+0.57}_{-0.89}$, together with an isothermal terminator temperature of $747^{+150}_{-155}$ K. We place stringent upper limits on CH$_4$, SO$_2$, and CS$_2$, finding no robust evidence for any sulphur-bearing species despite the intense irradiation received by the
planet. The inferred water abundance implies a strongly metal-enriched atmosphere. Elevated intrinsic temperatures can reconcile the non-detections of CH$_4$ and CS$_2$ through carbon–sulphur coupling, while the absence of SO$_2$ points toward a reduced atmospheric sulphur inventory or a near-solar to mildly enhanced C/O ratio, and places HD 106315 c near the transition between sulphur-rich and sulphur-poor chemical regimes.
Read the full abstract ▾
All authors A. Dyrek, R. Waters, S.-M. Tsai, M. Holmberg, B. Edwards, J. Pye, M. Güdel, N. Crouzet, R. van Gompel, J. Polman, F. Ardevol Martinez, D. Barrado, W. De Gruijter, Th. Henning, S. Kendrew, N. Khorshid, Y. Miguel, M. Min, M. Morales-Calderon, M. Topinka