Instrumentation and Methods for Astrophysics
Towards the exploration of astrophysical datacubes through volumetric rendering within CARTA
Ixaka Labadie-García, Adrianna Pińska, Angus Comrie et al. (+5 more)
Data products from astrophysical observations may contain three or more dimensions: most commonly two spatial dimensions and a third spectral dimension, and possibly additional axes such as polarisation or time. Visualising three-dimensional image data is particularly useful for analysing the kinematics and
evolution of various objects; however, the large scale of data produced by next-generation observatories and the complexity of displaying 3D data on a 2D screen make visualisation challenging. In this article, we present a scalable and interactive 3D visualisation approach within the astronomy software CARTA. We implemented a prototype 3D rendering widget with ThreeJS and known techniques to improve efficiency (e.g. compression, downsampling) and found that large datacubes up to 128 GB can be visualised locally with a loading time of a few minutes. We analysed the performance in the frontend and in the backend, finding that the bottleneck of our implementation lies in the frontend. This is due to storing the data in a single array in the frontend, unlike in the backend, where it is accessed and sent in blocks. This study paves the way for making 3D visualisation of large datacubes available to the community by implementing a 3D rendering widget in a future release of CARTA.
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All authors Ixaka Labadie-García, Adrianna Pińska, Angus Comrie, Michaela van Zyl, Manuel Parra-Royón, Susana Sánchez-Expósito, Lourdes Verdes-Montenegro, Julián Garrido
Solar and Stellar Astrophysics
Bright Metal-Poor Star Survey - I. Tomo-e Gozen narrow-band photometric survey and medium-resolution spectroscopic follow-up
Hiroko Okada, Takumi Iwasaki, Nozomu Tominaga et al. (+21 more)
We present the Tomo-e Gozen Bright Metal-Poor
Star Survey (TeMPS), a wide-area narrow-band photometric survey for bright metal-poor
stars in the northern sky. The survey uses the Tomo-e Gozen camera on the 1.05 m Kiso Schmidt
telescope with four narrow-band filters centered on the \ion{Ca}{2} H and K lines, the CH $G$ band, H$\alpha$, and a reference wavelength region. We review the survey strategy, photometric processing, and calibration of
metallicity and carbon abundance estimates derived from narrow-band colors. We further present medium-resolution spectroscopic follow-up with Nayuta/MALLS to validate the photometric selection and identify new metal-poor
stars. The current data set covers $\gtrsim 22,000$d̃eg$^{2}$ in all four bands with a total integration time of $\sim 100$ hr. The median limiting magnitudes at S/N = 20 correspond to $G\sim12.5$. By combining narrow-band photometry with archival broad-band photometry and Gaia distances, we estimate $T\_{\rm eff}$, $\log (g)$,
metallicity, and carbon abundance. Calibration against literature abundances derived from high-resolution spectra shows typical scatters of $< 0.3$ dex in
metallicity and $< 0.4$ dex in carbon abundance. We estimate
metallicities for $\sim 1.7$ million
stars and identify $\sim 16,000$ very metal-poor candidates with [M/H]$_{\rm NB,fin}<-2$. We show that Nayuta/MALLS medium-resolution spectra provide
metallicities consistent with high-resolution measurements, with a scatter of $\sim 0.27$ dex. Among 32 photometrically selected candidates followed up with MALLS, 24 are confirmed to have [M/H]$_{\rm MALLS}< -2$, including one newly identified
star with [M/H]$_{\rm MALLS}\simeq -3.4$. These results demonstrate that Tomo-e Gozen narrow-band photometry and MALLS medium-resolution spectroscopic follow-up efficiently select bright metal-poor
stars for future high-resolution abundance studies. (abbreviated)
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All authors Hiroko Okada, Takumi Iwasaki, Nozomu Tominaga, Wako Aoki, Satoshi Honda, Kurumi Furutsuka, Tadafumi Matsuno, Tomoki Morokuma, Takuma Suda, Miho N. Ishigaki, Naoto Kobayashi, Hidenori Takahashi, Yuu Niino, Satoshi Takita, Sohei Kondo, Yuki Mori, Kenzo Kinugasa, Shigeyuki Sako, Tomio Kanzawa, Hikaru Iwashita, Kenji Mitsui, Takeo Fukuda, Keiko Kaneko, Mitsuhiro Fukushima
High Energy Astrophysical Phenomena
Testing Narrow-jet Gamma-Ray Bursts as Sources of Ultrahigh-Energy Cosmic Rays
Saikat Das, Soebur Razzaque, Justin D. Finke et al. (+1 more)
Gamma-ray bursts (GRBs) have long been considered candidate sources of ultrahigh-energy
cosmic rays (UHECRs) due to their large energy release and relativistic outflows. The detection of multi-TeV $\gamma$-rays from GRB~221009A and its rarity have renewed interest in this connection and motivate considering an additional narrow-jet long GRB population in the local Universe. We investigate whether such a local narrow-jet population can contribute to the observed diffuse UHECR energy spectrum. We also examine the associated cosmogenic
neutrino and cascade $\gamma$-ray emissions to assess the multimessenger viability of this scenario. We fit the observed UHECR spectrum and mass composition data using three source-
evolution models: a uniform comoving source emissivity, a standard-jet GRB population tracing the
star formation rate (SFR), and a standard + narrow-jet GRB population tracing SFR. We propagate a mixed-composition UHECR injection and calculate the cosmogenic
neutrino and cascade $\gamma$-ray fluxes. The standard + narrow jet model fits the observed UHECR spectrum and composition, with the highest-energy flux dominated by the narrow-jet population confined to $z\le z_{\max,*}\simeq0.36$. This low-
redshift dominance lowers the cosmogenic
neutrino flux compared to the standard-jet GRB population. For the narrow-jet GRB population, the fit implies a baryon loading factor $\xi_{\rm CR}^{\rm nj}\simeq10$. Such a locally enhanced long-GRB population can therefore explain the highest-energy UHECR flux without violating current multimessenger constraints. Future UHE searches can further probe this scenario through the associated cosmogenic fluxes.
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All authors Saikat Das, Soebur Razzaque, Justin D. Finke, Siyao Xu
High Energy Astrophysical Phenomena · Cross-listed from nucl-th
Scale Invariance and Compact Star Matter
Hyun Kyu Lee and Won-Gi Paeng
We present discussions on the possibility of emerging hidden scale
symmetry, as a pseudo-conformal phase in super dense baryonic matter, using the velocity of sound as a criterion for a scale
symmetry window in hadronic dense matter. In the density dependent mean field approach à la Brown-Rho scaling, it has been observed that the interplay between vector
mesons and $ \chi$, one of the strongly correlated effects between
hadrons, is nontrivial such that the trace of the energy momentum tensor becomes density-independent in the super dense regime and the sound velocity approaches the conformal sound velocity for the pseudo-conformal phase. It is suggested that in the pseudo conformal phase the rearrangement terms induced by density dependent couplings do not spoil the hidden scale
symmetry in the compact
star matter. We elaborate further on the astrophysically observable quantities of the compact
stars and the implications for the parity doubling and the
quark-
hadron transitions.
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Instrumentation and Methods for Astrophysics
Optimal transport regularized dynamic radio interferometric reconstruction
Andy Nilipour, Kotaro Moriyama, Shiro Ikeda et al. (+2 more)
We propose a new technique for dynamic
video reconstruction of
radio interferometric data using the optimal transport (OT) distance as a regularizer within the regularized maximum likelihood (RML) framework. Compared to other commonly used regularization terms in RML and related prior-based approaches, the OT distance more naturally captures information including physical motion and promotes coherent dynamics. This property makes the OT regularization particularly suitable for dynamic imaging of astrophysical phenomena on minute timescales. We perform a series of tests on simulated very long baseline interferometric (VLBI) observations of Sagittarius A$^\ast$ (SgrA*), the supermassive black hole at the Galactic Center, with the Event Horizon
Telescope (EHT), using both
geometric and general relativistic magnetohydrodynamic models. We demonstrate that adding an OT regularization term yields significant improvements in dynamic reconstructions compared to those without it, as quantified by better recovery of orbital motion and higher dynamic cross-correlation metrics. Continued developments in OT theory across various fields, proposed extensions to the EHT network, and broad applicability to other VLBI networks make it so that OT regularization for dynamic
radio interferometric reconstructions will continue to be utilized and improved in the future.
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All authors Andy Nilipour, Kotaro Moriyama, Shiro Ikeda, Kazunori Akiyama, Mareki Honma
Solar and Stellar Astrophysics
NGTS clusters survey - VI: Stellar rotation in seven young open clusters within the PLATO LOPS2 field
Alexander Hughes, Edward Gillen, Matthew Battley et al. (+18 more)
We present NGTS measurements of rotation period distributions for FGKM
stars in seven young open clusters spanning ~40–700 Myr within PLATO's first long-stare LOPS2 field. We measure 1063 rotation periods, of which 479 are newly analysed as part of cluster specific rotation studies, whilst 63 are unique periods not reported in the recent TESS All-Sky Rotation Survey. Of the 1063 rotation periods, 285 are identified as likely binary or higher order multiple systems using colour-magnitude diagrams and Gaia astrometry. These are the first comprehensive rotation period distributions for Trumpler 10, NGC 2451B and Alessi 3, while extending existing distributions for NGC 2451A, NGC 2516, Collinder 135 and IC 2391, to create a fuller picture on the rotation state of young
stars in PLATO's LOPS2 field. We find that main-sequence solar-mass
stars in the ~40 Myr old NGC 2451B cluster, form a slow sequence that can be distinguished from their counterparts at ~70–80 Myr, thereby significantly reducing the age at which young stellar groups can be relatively aged via their rotation sequences. We also observe stalled
spin down from the age of NGC 2451A to at least that of NGC 2516 (~70–150 Myr) at masses $\gtrsim1$ $M_{\odot}$, supporting previous predictions that angular momentum redistribution and removal should result in a wave of stalled
spin down that propagates as a function of both mass and age. Finally, we provide a new age estimate for Alessi 3 of 687$\pm$106 Myr using differential gyrochronology age dating.
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All authors Alexander Hughes, Edward Gillen, Matthew Battley, Deepak Chahal, Beatrice Caccherano, David Anderson, Ioannis Apergis, Daniel Bayliss, Matthew Burleigh, Jorge Fernández Fernández, Michael Goad, George Harvey, James S. Jenkins, Alicia Kendall, James McCormac, Jose Moyano, Gavin Ramsay, Suman Saha, Jose Vines, Richard G. West, Peter J. Wheatley
Earth and Planetary Astrophysics
Narrow-Shell Stochasticity in Source-Sink Models of the Low Earth Orbit Environment
Jaewon Choi, Souvik Dhara and Harsha Honnappa
Deterministic source-sink models are widely used to assess the long-term
evolution, capacity, and sustainability of the low Earth orbit (LEO) environment. These models propagate shell-averaged populations through ordinary differential equations (ODEs), relying on individual collision, disposal, and decay events to average out within sufficiently large altitude shells. As constellation traffic is increasingly organized into kilometer- and sub-kilometer-scale shells, this averaging assumption becomes strained. We formulate the multi-shell, multi-species LEO environment as a Markov jump process and, from this formulation, recover the conventional source-sink ODE as a large-volume limit and derive a
stochastic differential equation (SDE) approximation whose fluctuations scale as V^{-1/2} in the per-shell volume V. The
diffusion approximation is validated against an exact discrete-event simulation of the underlying jump process. Sweeping V at fixed spatial density over the 450-800 km band, we find that the two descriptions agree at shell volumes comparable to those used in established source-sink models but diverge as shells narrow. At the finest shell volume considered, the mean debris population reaches roughly 4.5 times the ODE prediction, with several realizations undergoing runaway growth absent from the ODE trajectory. This departure is driven by nonlinear collision terms, through which population variance and covariance raise expected collision rates, generating further debris and reinforcing the collision-debris feedback. Narrow-shell stochasticity thus both widens the outcome distribution and shifts the expected trajectory. Because the
stochastic model shares its parameterization with the deterministic one, it provides a scale-consistent extension of existing source-sink models for evaluating shell configuration, collision risk, and long-term LEO sustainability.
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Earth and Planetary Astrophysics
Catastrophic tidal disruption of heterogeneous rubble piles: a tale of two regimes
John Wimarsson, Eric Frizzell, Martin Jutzi et al. (+1 more)
The way a rubble-pile body deforms or disrupts under the influence of tidal forces can be directly tied to its internal strength and configuration. Computational modelling of such tidal disruption events provides an indispensable numerical laboratory for constraining the origin and
evolution of small bodies in the Solar System. A majority of previous investigations into tidal disruption of rubble piles have mainly considered progenitors consisting of same-sized, spherical elements. Our study attempts to fill the existing gap in studies analysing the effect of aggregate heterogeneity on tidal disruption outcomes by varying element shape and size frequency distribution. Such heterogeneities have been shown to strongly influence rubble pile dynamics for impacts and rotational failure. We performed numerical simulations of parabolic and
hyperbolic tidal encounters between six unique rubble-pile progenitors and the Earth using the N-body code GRAINS. The resulting mass distributions of generated fragments and tidal chain morphologies for the different progenitors were further tied to the internal strength of rubble piles. Two regimes of tidal disruption are identified. In the first regime, closest to the
planet, the dynamic
evolution is dominated by tidal forces. Here, particle shape, size distribution and resolution appear to have little importance for the resulting distribution of fragment masses. In the second, shear-controlled regime, the internal structure of the progenitor begins to strongly influence the resulting tidal chain morphology and properties of the surviving fragments. Heterogeneity originating from the shape and size frequency distribution of elements in rubble pile models has a substantial effect on the outcomes of tidal disruption events. These parameters must be carefully taken into account when future studies attempt to tie results from numerical models to observations.
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All authors John Wimarsson, Eric Frizzell, Martin Jutzi, Fabio Ferrari
High Energy Astrophysical Phenomena
Source models of ultrahigh-energy cosmic rays
Bing Theodore Zhang
We investigate potential sources of ultrahigh-energy
cosmic rays (UHECRs) and their acceleration mechanisms, focusing on astrophysical phenomena associated with massive stellar deaths and supermassive black holes. These phenomena include gamma-ray bursts (GRBs), engine-driven
supernovae/hypernovae, magnetars, newly born
pulsars, binary
neutron star mergers (BNS), tidal disruption events (TDEs), and active galactic
nuclei (AGN). While high-luminosity GRBs (HL GRBs) are constrained as UHECR sources by high-energy
neutrino observations, low-luminosity GRBs (LL GRBs) and engine-driven
supernovae remain promising candidates, with intermediate-mass
nuclei as the dominant components. Compact binary mergers and $r$-process nucleosynthesis in
neutron-rich environments may also contribute to ultraheavy UHECRs. The composition of UHECRs from TDEs depends on the properties of the disrupted
stars. AGN, particularly
radio galaxies, remain promising sources, with acceleration occurring in their large-scale jets and lobes. Shear acceleration mechanisms have been proposed as a viable alternative for accelerating UHECRs, involving the re-acceleration of low-energy
cosmic rays and being compatible with the observed spectrum and composition. Future multi-messenger observations, especially from upcoming observatories, are expected to provide critical data to refine our understanding of UHECR origins, test existing models, and explore new acceleration mechanisms.
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Astrophysics of Galaxies
HURACAN: A comparison of stellar and interstellar proper motions inside L1688
M. Piecka, J. Alves, A. Rottensteiner et al. (+3 more)
The assumption that molecular clouds are kinematically coupled to the young stellar populations forming within them is observationally still poorly constrained. With the transverse component $v_{\textrm{t}}$ of the interstellar medium (ISM) motion being largely unknown, the three-dimensional kinematic state of even the closest clouds remains incomplete. We provide the first direct measurement of the transverse motion of the ISM inside the Ophiuchus cloud L1688 and compare it with the kinematics of the surrounding young stellar populations. The measurement was obtained using intensity-based image registration applied to archival data, allowing us to generate a proper motion field of the studied regions and determine the cloud's bulk motion, $(\mu_{\alpha^*},\mu_\delta)^{\mathrm{ISM}}_{\mathrm{median}}=(-3.0, -24.1)$ mas yr$^{-1}$. This motion differs from the kinematics of the youngest population in Upper Scorpius by $3\pm1$ km s$^{-1}$, highlighting the possibility of a bias when using
stars as a proxy for the ISM motion near
star-forming regions. By comparing the cloud's motion with that of the youngest stellar population in the region and the B-
star Oph S1 located within the cloud, we find that stellar feedback must have dynamically shaped the motion of the ISM over the last few million years. Furthermore, by studying a shell-like ISM structure appearing in L1688, we find evidence suggesting that this object is likely neither a typical Herbig-Haro object nor a
supernova remnant, with its origin remaining a mystery. Our results demonstrate that archival and future high-resolution near-infrared observations can and will continue to enable measurements of ISM transverse motions in nearby clouds, opening a new window for studying ISM dynamics that is not accessible when using radial velocities alone.
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All authors M. Piecka, J. Alves, A. Rottensteiner, S. Hutschenreuter, S. Meingast, L. Posch
Astrophysics of Galaxies
The solitary star cluster of the Andromeda XXV dwarf spheroidal
Chiara Crociati, Annette M. N. Ferguson, Gracie McGill et al. (+6 more)
We present Hubble Space
Telescope Advanced Camera for Surveys observations of Gep I, a globular cluster (GC) candidate in the low-mass ($M_{\star}\sim 6.5 \times 10^5\,M_{\odot}$) M31 dwarf spheroidal (dSph) satellite Andromeda XXV (And XXV). We confirm the nature of this object and provide the first detailed characterisation of its resolved stellar populations using a colour-magnitude diagram (CMD) that reaches 2 magnitudes below the horizontal branch. We compare Gep I's
metallicity and distance with those of the surrounding And XXV stellar population, and find them to be strikingly similar, consistent with a physical association between the GC and the dSph. Gep I is very extended ($R_h=24^{+5}_{-4}$ pc) and faint ($M_V = -4.5 \pm 0.2$ mag), similar to the
star clusters residing in other low-mass dwarf
galaxies. It is characterised by a very low
metallicity ($\rm [Fe/H] = -2.4^{+0.3}_{-0.4}\,$dex) and a red horizontal branch morphology, a combination also seen in suspected accreted GCs in the M31
halo and in the Local Group dwarf irregular
galaxy NGC 6822. While Gep I is most likely a genuine
star cluster, the current data do not exclude the tantalising possibility that it consists of And XXV
stars temporarily captured by a dark subhalo orbiting within the dSph's potential well.
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All authors Chiara Crociati, Annette M. N. Ferguson, Gracie McGill, Raffaele Pascale, Anna Genina, Pete B. Kuzma, Dougal Mackey, Alan W. McConnachie, Rokas Žemaitis
Earth and Planetary Astrophysics
Three-dimensional SPH simulations of the Caloris basin-forming impact: basin scaling, the gravity anomaly, and antipodal effects
Thomas Meier, Christian Reinhardt, Martin Jutzi et al. (+1 more)
The Caloris basin is the largest well-preserved impact structure on Mercury, yet its formation conditions, the origin of its positive
gravity anomaly, and its relation to the antipodal terrain remain poorly constrained. We present global, three-dimensional smoothed particle hydrodynamics simulations of the Caloris basin-forming impact with the pkdgrav3 code, including material strength. We survey 225 combinations of impactor radius, velocity, angle, and target thermal profile, complemented by simulations of up to two billion particles, which resolve the adopted 40 km crust by ten particle layers. At all resolutions, basin sizes are measured directly from the crust particles. The measured basin diameters follow a single power law in impactor radius, velocity, and angle, systematically steeper than idealized point-source crater scaling. The observed Caloris diameter is reproduced by a broad family of impactors favoring oblique incidence; sensitivity to resolution and crust thickness shifts this family toward smaller or slower impactors. All impactor material remaining in the basin region is vaporized, so our crust-like impactors leave no buried remnant. Instead, the impact thins the mantle and raises a local dome on Mercury's core. The dome's isolated
gravity signal is positive and centered on the basin, supporting the mantle-uplift origin proposed for the observed mascon. At the antipode, single seismic pulses cannot loft surface material when strength is included, yet accumulated strain exceeds the elastic limit. A kilometer-scale equivalent thickness of impact-derived material then converges on this weakened surface. Ejecta convergence contributed at least as much as seismic shaking to forming the terrain.
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All authors Thomas Meier, Christian Reinhardt, Martin Jutzi, Joachim Stadel
High Energy Astrophysical Phenomena
Anisotropy-driven constraints on the transition from Galactic to extragalactic cosmic-ray sources
Teresa Bister, Foteini Oikonomou and Damiano F. G. Fiorillo
The spatial distribution of the
cosmic-ray (CR) flux above $8\,\mathrm{EeV}$ exhibits a significant dipole in agreement with expectations from extragalactic sources following the large-scale structure. At the ankle, the direction changes suddenly and is compatible with the Galactic center for energies $\lesssim4\,\mathrm{EeV}$. We leverage the direction and strength of the dipole anisotropy as diagnostics of the possible sources of the intermediate-mass
nuclei below the ankle that cannot be associated with the continuation of the Peters cycle of lower-energy Galactic CRs. Using 3D-simulations of CR propagation in up-to-date Galactic
magnetic field models, we show that the dipole anisotropy of both continuous and transient individual Galactic sources and source distributions exceeds the measurements by $>3\sigma$. An extragalactic origin of the intermediate
nuclei below the ankle instead agrees with all data, where the observed change in dipole direction is guided by the fading heavy Galactic component dominant at the second knee.
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Solar and Stellar Astrophysics
Not so typical doubly eclipsing systems
Petr Zasche
Classical doubly eclipsing systems are
stars for which two distinct eclipsing periods that apparently come from one point source are detected. Through thorough analysis, the physical parameters of the component
stars of these systems can be revealed, and sometimes even the mutual motion of the two doubles around a common barycentre can be constrained. This is most typically done via study of the eclipse-timing variations for both pairs, whose behaviour should be opposite in manner to each other, as the two doubles revolve around a common barycentre. In this study, we present rather unusual systems for which such an easy approach does not work. The period changes are clearly detectable, but only for one pair. These unusual systems are V736 And (periods 0.3596 days and 0.3069 days); ASAS J074939-3037.0 (0.4417 d, 0.2648 d); OGLE BLG-ECL-123507 (1.0170 d, 2.9488 d); ASASSN-V J180818.54-684329.4 (0.3392 d, 3.3234 d); and CRTS J191726.4-543540 (0.3129 d, 2.8178 d). Several hypotheses are presented regarding the possible origins of such behaviour. However, a final decisive explanation is still yet to be determined.
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Cosmology and Nongalactic Astrophysics
Bumpy inflation from explosive particle production
Kaloian D. Lozanov, Xavier Pritchard and Misao Sasaki
We present a first-principles derivation of an effective inflaton potential with a bumpy feature. We consider the coupling of a spectator field \chi to the inflaton \phi such that \chi is massive enough for almost all values of \phi, but becomes massless when the inflaton crossed the value \phi_\star. This gives rise to a burst of \chi-particle production at \phi=\phi_\star. By taking the backreaction of the particle production, we obtain a bumpy feature in the effective potential. We discover that for certain choices of the interaction constants and field scale relevant for particle production, the backreaction-induced bumpy effective potential can lead to a sizable enhancement in the
curvature perturbation. In particular, the enhancement can be large enough to generate observationally relevant amounts of primordial black holes and
stochastic gravitational wave backgrounds.
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Earth and Planetary Astrophysics
The true masses of radial-velocity exoplanets constrained by stability
Xander Byrne and Amy Bonsor
Exoplanets discovered with the radial velocity method suffer from a mass-inclination degeneracy: only the minimum mass $M_{\rm min} = M \sin i$ is measured. An
exoplanet with an Earth-sized minimum mass could actually therefore be a sub-Neptune, or even a gas giant. However, for compact multi-
planet systems, the inclination angle cannot be too low, as this would imply masses so large that the system would be dynamically unstable on time-scales shorter than the age of the system. We present CINEMAS, a
Bayesian framework to constrain the inclinations - and hence true masses - of radial-velocity
exoplanets in flat multi-
planet systems, by accounting for dynamical stability. Applying this framework to five compact exoplanetary systems, we cut upper limits on the true masses of their
planets by as much as 45%. As two examples, the masses of the four Barnard's
Star planets are constrained to all be below $0.6~M_{\oplus}$ to at least 95% confidence; and the three gas giants orbiting HD 184010 are found to be intermediate in mass between Saturn and Jupiter. With only ~1% of planetary systems being inclined enough to transit, methods of studying non-transiting systems are vital for constraining the properties of nearby
exoplanets.
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High Energy Astrophysical Phenomena
A Bayesian Framework for Constraining Magnetar Magnetic Fields from Repeating FRB Statistics
Can-Min Deng and Hao-Hao Chen
Fast
radio bursts (FRBs) are widely considered to be associated with magnetars, motivated by the detection of an FRB-like
radio burst from the Galactic magnetar SGR~1935+2154. However, constraining the
magnetic field strength of extragalactic FRB sources remains challenging. In this work, we develop a
Bayesian framework that models FRB time–energy sequences as a marked point process, combining burst waiting-time statistics with energy distributions to quantify the
magnetic field strengths required to sustain the observed bursting activity under the magnetar powered scenario. Applying this method to a sample of repeating FRBs, we derive constraints on their
magnetic fields by incorporating an empirical prior on the
radio emission efficiency calibrated from the Galactic event. Under a conservative assumption for the activity duty cycle, most sources require
magnetic energy reservoirs consistent with magnetar strength fields, with characteristic field strengths of order $10^{13}$–$10^{15}$ G, although the constraints remain sensitive to the poorly known efficiency and duty-cycle parameters. FRB~20200120E provides an interesting case with a substantially lower field requirement, highlighting the importance of source environment and evolutionary history in interpreting FRB activity. Our framework provides a statistical approach for connecting transient burst properties with
magnetic energy reservoirs, with potential applications to FRBs and other magnetically powered transients.
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High Energy Astrophysical Phenomena
Energy-dependent slow collective flavor conversion of supernova neutrinos
Heng-Hao Chen, Ian Padilla-Gay, Meng-Ru Wu et al. (+2 more)
We study collective slow flavor conversion (SFC) of
supernova neutrinos with multi-energy, multi-angle simulations for three representative
neutrino spectra in the early
accretion, late
accretion, and cooling phases, in which multiple crossings between the initial electron- and heavy-lepton-flavor spectra are present. By numerically solving the
neutrino quantum kinetic equations in a local periodic box, we find that SFC triggered predominantly by the spatially inhomogeneous instabilities drives the system toward a spatially coarse-grained, quasi-stationary state, whose flavor conversion probability depends strongly on energy, angle, and the
neutrino mass ordering. While we find that not all of the initial spectral crossings are completely erased in the final state, a simple, box-like analytical prescription inspired by studies of fast flavor conversions, which eliminates the spectral crossings, can reasonably approximate the post-SFC spectra. Using the initial and post-SFC spectra, we also evaluate the changes of the corresponding $\nu_e$ and $\bar\nu_e$ heating rates as well as the absorption
equilibrium electron fraction ($Y_e$). Within the considered scenarios, we find that the heating rates are generally enhanced by up to $\sim 80\%$ due to the net conversion of $\nu_x$ to $\nu_e$ (and $\bar\nu_x$ to $\bar\nu_e$) above their crossing energy, provided that the energy spectra above the crossing energy differ substantially. For the absorption
equilibrium $Y_e$, spectra changes due to SFC increase it by $\sim 0.03$ due to the relatively more enhanced $\nu_e$ absorption rate than $\bar\nu_e$, which potentially drives
supernova materials to be more
proton-rich. These results highlight the importance of energy-dependent treatments of SFC for
supernova neutrinos.
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All authors Heng-Hao Chen, Ian Padilla-Gay, Meng-Ru Wu, Sajad Abbar, Zewei Xiong
Earth and Planetary Astrophysics
Alkali lines at extreme densities and their impact on giant planet interior structure
Louis Siebenaler, Nicole F. Allard, Esther van Dijk et al. (+1 more)
Alkali lines, in particular the sodium Na $D$ (5891$\AA$, 5897$\AA$) and potassium K $D$ (7667$\AA$, 7701$\AA$) resonance doublets, are dominant opacity sources in giant
planets over a wide range of temperatures ($\gtrsim$1000K). Their strong pressure-broadened wings significantly influence the thermal structure of giant
planets, especially at high pressures. Most detailed line-profile calculations have so far been limited to perturber densities up to $10^{21}$cm$^{-3}$. However, conditions in the deep atmospheres and interiors of giant
planets can reach significantly higher densities, making the temperature gradients increasingly uncertain. We determined how physically consistent collisional broadening of the Na $D$ and K $D$ lines at extreme densities affects opacity calculations and consequently the inferred interior structure of giant
planets. We computed detailed Na $D$ and K $D$ line profiles using unified line theory, extending to molecular hydrogen perturber densities of $n_{\rm H_2} = 5 \times 10^{22}$cm$^{-3}$, which translates to pressures up to $\sim$ 20kbar. The revised cross sections were incorporated into Rosseland mean opacity tables, which were then used to evaluate their effect on planetary thermal structures. At densities $n_{\rm H_2} > 10^{21}$cm$^{-3}$, the line profiles predicted by unified line theory exhibit significantly stronger wings than commonly used Voigt profiles, as well as density-dependent line shifts, which substantially increases Rosseland mean opacities. Consequently, the radiative-convective boundary of warm and hot giant
planets can shift to lower pressures, producing warmer interior adiabats and increasing inferred core masses. We further find that Jupiter is unlikely to host a stable radiative layer at the present time or throughout most of its
evolution, as the required Na and K abundances for this are well below observational constraints.
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All authors Louis Siebenaler, Nicole F. Allard, Esther van Dijk, Yamila Miguel
Cosmology and Nongalactic Astrophysics
Derivative hierarchy as the origin of kernel-dependent trends in Gaussian process reconstructions of the hubble parameter
Afaq Maqsood
We perform a model independent reconstruction of the
cosmic expansion history using Gaussian Process regression, investigating how the smoothness properties of covariance kernels influence the inferred Hubble parameter. Using 32
cosmic chronometer measurements, we reconstruct $H(z)$ with the Matérn $3/2$, $5/2$, $7/2$, $9/2$, and Squared Exponential kernels, which form a well-defined hierarchy of differentiability. Across this hierarchy, we observe a systematic and monotonic trend in which increasing kernel smoothness is associated with progressively lower reconstructed values of the present-day Hubble constant $H_0$, accompanied by reduced statistical uncertainties. Rather than indicating a statistical preference for a specific kernel, this behaviour reflects the sensitivity of non-parametric reconstructions to the assumed smoothness prior encoded in the covariance function. The same ordering is reflected in descriptive goodness-of-fit statistics and remains stable when incorporating recent DESI DR2 BAO measurements and performing jackknife resampling tests, demonstrating robustness against individual data points and
dataset variations. Additional analysis of derivative reconstructions shows that differences in kernel differentiability propagate into the local slope of the expansion history, providing a consistent interpretation of the observed ordering in $H_0$. Our results highlight that kernel smoothness plays an important role in Gaussian Process reconstructions and should be carefully accounted for when interpreting non-parametric cosmological inferences.
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Earth and Planetary Astrophysics
Study on the Venusian Atmospheric Thermal Structure: A Comparative Analysis between VEX/Akatsuki and Venus-GRAM/VCD
Soumyaneal Banerjee, R. K. Choudhary, Keshav R. Tripathi et al. (+5 more)
We investigate the thermal structure of the Venusian middle atmosphere between 45 and 80 km using
radio occultation (RO) measurements from Venus Express and Akatsuki spanning 2006-2024. Retrieved temperature profiles are compared with climatological predictions from the Venus-GRAM and the Venus
Climate Database (VCD). Systematic deviations exceeding 10 K are observed between the RO temperatures and model climatologies, particularly at high latitudes in both hemispheres. The long-term
dataset further reveals a possible decadal-scale temporal variability in temperatures across the low-to-mid latitude regions. This variability becomes less coherent at higher altitudes. A combination of post-stratification and bootstrap analysis on the temperature anomalies indicates that the observed temporal variability at low-to-mid and polar latitudes is not readily explained by the latitudinal sampling bias quantified using the adopted analysis, while the trends at mid-to-high latitudes are affected by sparse and uneven RO sounding. Sensitivity tests using modified cloud albedo inputs in VCD simulations show that adjusting cloud radiative forcing partially reconciles the discrepancies, especially at the lower altitudes, below 60 km. However, above the cloud top, at the lower latitudes, the divergence from the observations increases significantly, thereby failing to provide a general reconciliation between VCD and RO. These results highlight the need for updated empirical climatologies incorporating recent RO measurements and for improved physical parameterizations in Venus general circulation models to better capture the global variability in the
planet's middle atmosphere.
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All authors Soumyaneal Banerjee, R. K. Choudhary, Keshav R. Tripathi, K. M. Ambili, J. Oschlisniok, Silvia Tellmann, T. Imamura, H. Ando
Solar and Stellar Astrophysics
Classical Cepheids in the JWST and Roman Era: A New Theoretical Framework and its Metallicity Dependence
Giulia De Somma, Marcella Marconi, Vincenzo Ripepi et al. (+7 more)
Classical Cepheids are fundamental distance indicators that anchor the
cosmic distance ladder through their Period-Luminosity, Period-Luminosity-Color, and Period-Wesenheit relations, while also providing valuable constraints on young stellar populations. Recent advances in space-based near-infrared observations highlight the need for theoretical calibrations of Classical Cepheid observables in modern photometric systems optimized for precision distance-scale applications. This work provides a homogeneous theoretical framework for Classical Cepheids in the JWST/NIRCam and Roman/WFI systems and explores their use as standard candles in the near-infrared. We exploit an extensive grid of nonlinear convective pulsation models spanning a broad range of masses, effective temperatures, periods,
metallicities, convective efficiencies, and mass-luminosity relations. We derive mean magnitudes, colors, pulsation amplitudes, amplitude ratios, and new theoretical Period-Luminosity-Color, Period-Wesenheit, and metal-dependent Period-Wesenheit relations. The theoretical Wesenheit relations are compared with recent JWST observations of Classical Cepheids in six SN Ia host
galaxies from the SH0ES collaboration. We find excellent agreement between predictions and observations, with the largest systematic effects arising from the adopted mass-luminosity relation. Theoretical distance moduli are fully consistent with empirical JWST determinations when a mildly overluminous mass-luminosity relation is adopted instead of the canonical one. These results provide a self-consistent pulsation-based calibration for JWST and Roman observations and a theoretical framework for future precision studies of the local distance scale.
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All authors Giulia De Somma, Marcella Marconi, Vincenzo Ripepi, Roberto Molinaro, Ilaria Musella, Silvio Leccia, Teresa Sicignano, Erasmo Trentin, Mami Deka, Laura Salmeri
Solar and Stellar Astrophysics
Carbon in J0815+4729: Casting a shadow of doubt on the interpretation of CH absorption in the most primitive stars
Junbo Zhang, Carlos Allende Prieto, Yeisson Osorio et al. (+7 more)
Aims. We revisit the carbon abundance in the primitive iron-poor
star J0815+4729 ([Fe/H] = -5.49). J0815+4729 is so carbon-enhanced and oxygen-rich that, in addition to CH and C2 molecular lines, weaker neutral atomic transitions are measurable in its spectrum, providing a unique opportunity to explore the line formation of C I and O I transitions in such an extremely iron-deficient
star. Methods. Based on high-resolution spectroscopy and newly constructed atomic models for carbon and oxygen, we present the first investigation to derive carbon and oxygen abundances of this hyper iron-poor
star from neutral atomic transitions under non-local thermodynamic
equilibrium (NLTE) conditions. Results. The carbon abundance derived from C I lines is A(C)NLTE = 8.08+-0.07, consistent with that inferred from C2 lines (A(C)LTE =7.96 +- 0.08), but around 0.6 dex higher than the value from CH lines (A(C)LTE = 7.47 +- 0.17). Since CH lines are the most commonly-used carbon abundance indicator for extremely metal-poor
stars, this result casts doubt on the quantitative interpretation of CH absorption in the most primitive
stars. We confirm that J0815+4729 is one of the most carbon-enhanced
stars with [Fe/H] <= -4.5 known to date. We have also determined A(O)NLTE as 7.25 +- 0.11, with NLTE corrections of around -0.11 dex. The carbon-to-oxygen ratio of the
star is [C/O] = 1.06 +- 0.1.
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All authors Junbo Zhang, Carlos Allende Prieto, Yeisson Osorio, Jonay I. González Hernández, David S. Aguado, Ivan Hubeny, Shuai Liu, Jianrong Shi, Rafael Rebolo, Gang Zhao
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
$\mu$DM: a new mechanism for the baryon-dark matter coincidence
Wen Yin
For a relativistically decoupled thermal relic, the dark-matter energy-to-
entropy ratio scales as $\rho_{\rm DM}/s\sim 10^{-3}m_{\rm DM}$. This is the familiar hot-dark-matter abundance relation. Immediately after weak-sphaleron freeze-out, the baryon asymmetry can be parametrized as $\rho_{\rm baryon}/s\sim 10^{-4}|\mu_B|$. Here $\mu_B$ is the baryon-number chemical potential. We propose a new class of models, called chemical-potential-matched dark matter ($\mu$DM), in which $|\mu_B|\sim m_{\rm DM}$, thereby providing a new route to the baryon-dark matter coincidence. As a concrete example of $\mu$DM, we consider an Affleck-Dine field whose excitations constitute dark matter. We also briefly discuss spontaneous electroweak baryogenesis associated with
axion-like-particle walls. In the absence of
entropy dilution, this coincidence mechanism generically points to dark matter in the eV-keV mass range. Its momentum distribution can nevertheless be cold if thermal production is dominated by Bose-enhanced stimulated emission. Alternatively,
entropy dilution after both the dark-matter and baryon yields are fixed allows masses up to the MeV scale.
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Astrophysics of Galaxies
SERENADE III: Insight into the Origin of the High Dust Temperature and High [O III]/[C II] Ratio at $z\gtrsim6$
Ikki Mitsuhashi, Yuichi Harikane, Hiddo S. B. Algera et al. (+10 more)
We present an analysis of ALMA high-frequency observations of nine bright Lyman-break
galaxies at $5.8<z_{\rm spec}<8.3$. Our sample consists of five
galaxies at $z\sim6$ newly observed in Band-9 and/or 10, allowing us to better constrain the dust temperature ($T_{\rm dust}$) in a statistical sample of $z\gtrsim6$
galaxies. Our measurements of the dust temperature at $z\sim6-9$ suggest most of the
star-forming
galaxies show $T_{\rm dust}\sim40\,{\rm K}$ on average, whereas three
galaxies show significantly higher $T_{\rm dust}$ ($\gtrsim60\,{\rm K}$). We find a potential negative correlation between $T_{\rm dust}$ and gas-phase
metallicity with $T_{\rm dust}\propto Z^{-0.50\pm0.19}$, implying decreased dust shielding and efficient dust heating in low-
metallicity environments. Given the systematic offset of $T_{\rm dust}$ between $z\sim0$ and $z\sim6-9$ at fixed
metallicity, we find $T_{\rm dust}$ is well described by sSFR as well as $Z$ with $\log T_{\rm dust}=-0.25^{+0.03}_{-0.04}\times(\log Z-0.57\times\log {\rm sSFR})+4.88^{+0.47}_{-0.43}$ across $z\sim0$ to $z\sim6-9$. Simultaneously with the dust continuum, these observations cover the [OI]63$\mu$m emission line for five
galaxies, which traces dense neutral gas. We find a lower [CII]/[OI] ratio in $z\gtrsim6$
galaxies than in local samples, suggesting that [CII] becomes fainter due to collisional de-excitation at high gas density. Combining the [OI], [OIII], and [CII] lines and cloudy modeling, our results imply $\log U_{\rm ion}\sim-2$ and $\log n_{\rm H}\,[{\rm cm}^{-3}]\sim2.5$ in $z\gtrsim6$
galaxies, which is $\sim3-10\times$ higher $U_{\rm ion}$ and $\sim2-3\times$ higher $n_{\rm H}$ than the local samples. The combination of these enhanced $U_{\rm ion}$ and $n_{\rm H}$ naturally explains the high [OIII]/[CII] ratio at $z\gtrsim6$.
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All authors Ikki Mitsuhashi, Yuichi Harikane, Hiddo S. B. Algera, Tom J. L. C. Bakx, Andrea Ferrara, Akio K. Inoue, Masatoshi Imanishi, Kotaro Kohno, Yoshiaki Ono, Yuma Sugahara, Hideki Umehata, Livia Vallini, Jorge A. Zavala
High Energy Astrophysical Phenomena
ANRe-M1: a GPU-accelerated numerical relativity code with multi-energy M1 neutrino transport
Takami Kuroda and Masaru Shibata
We present ANRe-M1 (Accelerated Numerical Relativity code with multi-energy M1
neutrino transport), a performance-portable, GPU-accelerated code for multidimensional core-collapse
supernova simulations in full general relativity. ANRe-M1 builds on our original CPU-based Fortran framework and is implemented in C++ using Kokkos. It retains the underlying general-relativistic
neutrino-radiation-hydrodynamics
algorithms while redesigning the data layout, parallel decomposition, and
memory-access patterns for accelerator-resident execution. The spacetime sector employs the BSSN–Z4c formulation and is coupled to relativistic hydrodynamics and energy-dependent M1
neutrino transport. We validate the implementation through a suite of hydrodynamic, radiation-transport, and dynamical-spacetime tests, together with comparisons to results from an earlier code-comparison study. We further demonstrate its applicability with a representative three-dimensional stellar-collapse computation including multi-energy
neutrino transport. For the
benchmark and computing systems considered here, ANRe-M1 runs approximately an order of magnitude faster on a cluster of AMD MI300A accelerated processing units than the Fortran version on a CPU cluster. When the allocation is increased from 2 to 128 MI300A APUs, the aggregate throughput rises by a factor of 39.7, corresponding to a weak-scaling efficiency of 62 per cent relative to the two-APU case. These results establish ANRe-M1 as an efficient and portable framework for long-term, multidimensional
supernova simulations on current and forthcoming accelerator-based supercomputers.
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Cosmology and Nongalactic Astrophysics
ELUCID-DESI II. Revealing dark matter mass, tidal, and velocity (MTV) fields using galaxy group phase information
Qingyang Li, Xiaohu Yang, Wensheng Hong et al. (+24 more)
We introduce a novel method for reconstructing the
cosmic mass, tidal, and velocity (MTV) fields over the
redshift range $0 < z < 0.6$ using the phase information of
galaxy groups. This approach replaces the explicit theoretical bias correction typically needed to relate
galaxy groups to the underlying dark matter density field with a simulation-calibrated statistical mapping, reducing a major source of systematic uncertainty and making the method directly applicable to spectroscopic
redshift surveys such as the DESI Bright
Galaxy Survey (BGS). We evaluate the performance of our MTV reconstruction pipeline with mock
redshift surveys that include a comprehensive set of observational selection effects. The
galaxy groups used as tracers are identified with an extended
halo-based group finder applied to the DESI mock
galaxy catalogue with an apparent magnitude limit of $m_z < 19.65$, yielding a
galaxy number comparable to that of the DESI BGS faint sample ($m_r < 20.175$). Our tests show that the reconstructed velocities are accurate and unbiased, with a residual dispersion of $\sim 120\ \mathrm{km\,s^{-1}}$ across the
redshift bins. The recovered velocity field allows us to shift
galaxy groups to their real-space positions, thereby correcting for the Kaiser effect. By iteratively applying this Kaiser correction to the
galaxy groups, we further reconstruct the tidal field and the mass-density distribution. The reconstruction is stable with respect to the grid resolution. Overall, our results demonstrate that this group-based phase-space reconstruction provides a robust pathway to recovering the dark matter MTV fields, with strong prospects for application to DESI BGS data.
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All authors Qingyang Li, Xiaohu Yang, Wensheng Hong, Feng Shi, Youcai Zhang, Jiaqi Wang, Junde Li, Yiyang Guo, Yingxiao Song, Huiyuan Wang, Yan-Chuan Cai, Yizhou Gu, Chengze Liu, Jiaxin Han, Zhongxu Zhai, Yu Yu, Yipeng Jing, Houjun Mo, Yuyu Wang, Hao-Ran Yu, Yingjie Peng, Weiguang Cui, Qi Guo, Liang Gao, Xi Kang, Weipeng Lin, Jie Wang
High Energy Astrophysical Phenomena
Optical Discovery of New and Candidate Galactic Supernova Remnants Plus Optical Imaging of the Monogem Supernova Remnant
Robert A. Fesen, Marcel Drechsler, Bray Falls et al. (+16 more)
We report the discovery of new and candidate Galactic
supernova remnants made through over 2000 hours of H$\alpha$ and [O III] imaging using amateur class instrumentation. These nebulae range from 0.5 to over 8 degrees in size. Five of these, namely G27.8-17.1, G115.6+9.2, G190.5+25.3, G195.9+2.2 and G239.9+7.0 exhibit low-dispersion optical spectra indicating shock emission by the presence of strong [S II] $\lambda\lambda$6716,6731 and [O I] $\lambda$6300 line emissions relative to H$\alpha$, or exhibit a nonradiative shock generated Balmer dominated spectrum. Their filamentary emission morphology also supports the presence of interstellar shock fronts. Three other optical nebulae, G191.3+11.1, G205.7-1.7, and G305.4-0.7 appear likely to be remnants and are proposed as new SNR candidates. We also present [O III] and H$\alpha$ images of optical filaments associated with the 25 degree diameter Monogem Ring SNR which reveal extensive emission-line filaments around most of the remnant's X-ray boundaries. Deep images of the X-ray suspected remnant G190.4+12.5 and the large and [O III] emission dominated SNR G206.6+6.1 seen toward or near the Monogem SNR are also included. Key findings of this work include: 1) optical surveys can sometimes detect SNRs better than
radio and X-ray SNR searches, 2) Balmer nonradiative shocks appear not uncommon in high Galactic latitude SNRs, and 3) faint Ø3 emission dominated SNRs may have been missed in prior H$\alpha$ emission only surveys.
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All authors Robert A. Fesen, Marcel Drechsler, Bray Falls, Tim Schaeffer, Justin Anderson, Deepanshu Arora, Werner Becker, Carl Bjork, Steeve Body, Laurent Huet, Tarun Kottary, Mathew Ludgate, Nicolas Martino, Manuel Peitsch, Wolfgang Reich, Jose Rodrigues, Yann Sainty, Patrick Sparkman, Sean Walker
High Energy Astrophysical Phenomena
Spectro-Polarimetric Properties of CHIME FRB Sources
Dengke Zhou, Yi Feng, Jiaying Xu et al. (+2 more)
Fast
radio bursts (FRBs) are enigmatic millisecond-duration
radio transients whose polarization properties offer crucial insights into their origins and environments. In particular, low-frequency depolarization—quantified by the parameter \(\sigma_{\mathrm{RM}}\)—probes the complex magneto-ionic medium surrounding the progenitor, and has been observed across a population of repeating FRBs. We present a systematic spectro-polarimetric analysis of repeating and non-repeating FRBs using observations from the Canadian Hydrogen Intensity Mapping Experiment (CHIME). For 28 repeating FRBs, we measure \(\sigma_{\mathrm{RM}}\), expanding the known sample from 14 to 36 sources (an increase by a factor of 2.6). The kernel density estimate (KDE) of the repeating population peaks at \(1.3\ \mathrm{rad\,m^{-2}}\), with approximately 70% of the sources showing \(\sigma_{\mathrm{RM}} \gtrsim 1\ \mathrm{rad\,m^{-2}}\), implying that most reside in complex magneto-ionic environments. For 70 non-repeating FRBs, we investigate four spectro-polarimetric models; no source exhibits significant depolarization with \(\sigma_{\mathrm{RM}} \gtrsim 5\ \mathrm{rad\,m^{-2}}\). Roughly half of the non-repeaters are consistent with a constant linear polarization fraction across frequency. We caution, however, that these results may be affected by the limited frequency coverage of CHIME. Future ultra-wideband polarimetry, spanning widely separated frequencies, will overcome current observational biases, enable precise \(\sigma_{\mathrm{RM}}\) measurements, and substantially deepen our understanding of FRB environments.
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All authors Dengke Zhou, Yi Feng, Jiaying Xu, Chenyuan Xu, Jianhua Fang
Solar and Stellar Astrophysics
Bifrost spectral inversions: Fast non-LTE solar chromospheric diagnostics from 3D simulations
Elias R. Udnæs, Tiago M. D. Pereira, Ignasi J. Soler Poquet et al. (+1 more)
Modern solar observatories produce vast amounts of detailed spectral data. To infer atmospheric parameters from these data, in particular for the solar chromosphere, requires immense computational resources. This problem is becoming more acute as spatial resolution improves, and faster methods are much needed to make sense of the data. Archive-based inversions provide a cost-effective way to infer atmospheric parameters from solar spectra; they involve building databases of synthetic spectra and atmospheric models. We extended this idea to a k-nearest neighbour inversion with non-LTE chromospheric spectra from a 3D radiative-magnetohydrodynamic simulation. Our database consists of 150 million Ca II 8542 Å line profiles from a magnetically quiet simulation. We validated our method on a different simulation and then applied the database inversion to high-cadence observations taken with the Swedish 1-m Solar
Telescope. We find excellent agreement between the observed and fitted spectra for almost the entire field of view. We recovered the chromospheric temperature and line-of-sight velocity and calculated the uncertainty in their inversions. The gas temperature has small uncertainties over a broad range of optical depths, and we recover a physically consistent solution, even beyond the line sensitivity region. Compared with the traditional inversion method, our approach is four orders of magnitude faster. Limitations and future improvements of the method are discussed.
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All authors Elias R. Udnæs, Tiago M. D. Pereira, Ignasi J. Soler Poquet, Luc Rouppe van der Voort