Earth and Planetary Astrophysics
A temperate sub-Neptune transiting the M4 Dwarf TOI-210 identified by NIRPS and TESS – Uncovering hidden M-dwarf planetary systems in the near-infrared
C. Cadieux, B. N. Skinner, F. Bouchy et al. (+63 more)
Super-Earths and sub-Neptunes dominate the
exoplanet population, yet their compositions, formation mechanisms, and capability of retaining atmospheres remain poorly understood. M-type
stars offer a unique opportunity to investigate these questions, thanks to their favorable
planet-to-
star radius and mass ratios and the diversity of planetary systems they host. We aim to characterise the planetary system of the M4 dwarf TOI-210, in which TESS during its primary mission identified one transiting
exoplanet candidate at $P= 9.01$ days. We combine multi-technique observations, including transits from 40 sectors of TESS and ground-based follow-up with LCOGT and ExTrA, and radial velocities (RV) from NIRPS obtained as part of its Guaranteed Time Observations program. These data were analysed using a
Bayesian framework to constrain stellar, planetary, and orbital parameters. We confirm TOI-210 b, a temperate sub-Neptune ($T_{\rm eq} = 368 \pm 9$ K) with a mass of 6.75 $\pm$ 1.25 M$_{\oplus}$ and a radius of 2.234 $\pm$ 0.074 R$_{\oplus}$. Its bulk density implies a volatile-rich composition, either as an extended H/He atmosphere with mass fraction of approximately 1% (gas dwarf), a substantial water reservoir comprising at least 29% of the mass (2$\sigma$ lower limit; water world), or a mixture of both. The NIRPS RVs show moderate evidence ($\Delta \ln Z = 5.9$) for at least one non-transiting
exoplanet interior to TOI-210 b. In a targeted search, we identify two Keplerian signals at 2.15 and 3.76 days, with minimum masses of 3.2 $\pm$ 0.8 M$_{\oplus}$ and 4.4 $\pm$ 1.0 M$_{\oplus}$, respectively, that provide a plausible explanation for the observed RV variations. If these signals are
planets, the absence of transits in the TESS photometry implies mutual inclinations with TOI-210 b above 2.3-3.5$^{\circ}$.
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All authors C. Cadieux, B. N. Skinner, F. Bouchy, E. D. Gillis, V. Bourrier, R. Doyon, L. Y. Messamah, B. L. Canto Martins, A. L'Heureux, Y. S. Messias, J. M. Almenara, A. K. Stefanov, X. Bonfils, K. A. Collins, H. M. Relles, C. Rodríguez, P.-A. Roy, A. Shporer, G. Srdoc, S. Taylor, C. Ziegler, R. Allart, K. Al Moulla, É. Artigau, F. Baron, S. C. C. Barros, F. Bélanger, B. Benneke, M. Bryan, T. Ciolak, R. Cloutier, N. J. Cook, N. B. Cowan, E. Cristo, L. Dang, J. R. De Medeiros, X. Delfosse, E. Delgado-Mena, X. Dumusque, D. Ehrenreich, D. O. Fontinele, T. Forveille, J. Gagné, M. J. Hobson, P. Lamontagne, I. C. Leão, R. de Lima Gomes, C. Lovis, L. Malo, C. Melo, L. Mignon, C. Mordasini, N. Nari, L. Parc, R. Rebolo, R. Rosener, J. Rowe, N. C. Santos, D. Ségransan, A. Srivastava, A. Suárez Mascareño, S. Udry, D. Valencia, G. Wade, J. P. Wardenier, D. Weisserman
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
GAIA meets LZ: a high velocity tail-tale sign for dark matter
Anirban Das, Subhabrata Majumdar, Manibrata Sen et al. (+1 more)
The interpretation of high-energy nuclear recoils in direct-detection experiments can depend sensitively on the high-velocity tail of the galactic dark matter (DM) distribution. The LUX-ZEPLIN (LZ) experiment has recently reported an event, LZ230616, with nuclear recoil energy 248 $\pm$ 23 (stat) $\pm$ 23 (sys) keV, while the Gaia mission has provided an unprecedented view of the kinematics and mass distribution of the Milky Way. We bring these two probes together to investigate the inelastic DM interpretation of LZ230616, using a velocity distribution inferred from Gaia-informed galactic model. Compared to the Standard
Halo Model, the resulting distribution has a lower escape speed and a significantly suppressed high-velocity tail, with a higher local density. We find that while the exothermic interpretation is largely insensitive to this change, the endothermic interpretation requires substantially larger scattering cross sections and smaller mass splittings. Furthermore, using simulation-based study of the gravitational effects of the Large Magellanic Cloud, we show that the high-velocity tail can extend the allowed endothermic parameter space towards lower DM masses and larger splittings. Our results demonstrate how combining direct searches for DM detection with precision measurements of galactic dynamics can qualitatively affect the particle-physics interpretation of high-energy nuclear recoils.
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All authors Anirban Das, Subhabrata Majumdar, Manibrata Sen, Amogh Srivastav
High Energy Astrophysical Phenomena
Fast radio burst - persistent radio source systems III. The relation between PRS luminosity and FRB rotation measure
D. Pelliciari, G. Bernardi, L. Bruno et al. (+5 more)
Fast
radio bursts (FRBs) are millisecond-duration
radio transients of extragalactic origin whose physical origin remains uncertain. A small fraction of FRBs are known to repeat, and some of them are associated with persistent
radio sources (PRSs), interpreted as synchrotron-emitting nebulae surrounding the FRB source. In the context of magnetar-based models, the rotation measure (RM) of an FRB is expected to correlate with the spectral luminosity of its associated PRS, providing a probe of the physical properties and
evolution of the nebula. We investigate the relation between FRB RM and PRS spectral luminosity, constrain the characteristic size of the PRS nebulae, and use the intrinsic scatter of the relation to investigate evolutionary scenarios for FRB–PRS systems. We analyse a sample of 50 FRB sources with known RM, including both PRS detections and spectral luminosity upper limits, using a
Bayesian MCMC framework that jointly accounts for detections and non-detections. We model the luminosity–RM relation as $L_\nu \propto \zeta_e \gamma_c^2 R^2 {\rm RM}^\beta$, constraining the characteristic nebular size $R$ and the RM scaling index $\beta$. For the full sample, we obtain $R = 0.016^{+0.115}_{-0.014}$ pc at $1\sigma$ confidence for a free $\beta$, while fixing the RM dependence to the canonical linear scaling, $\beta = 1$, gives $R = 0.008^{+0.058}_{-0.007}$ pc. The data mildly favour super linear RM scalings, although the inferred values of $\beta$ remain consistent with $\beta = 1$ within $2\sigma$. We find a substantial intrinsic scatter in the luminosity–RM relation, significantly larger than previous estimates based on confirmed PRSs alone. Interpreting this scatter within evolutionary models, our results favour scenarios involving efficient particle acceleration and/or rapid nebular expansion.
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All authors D. Pelliciari, G. Bernardi, L. Bruno, M. Pilia, P. Esposito, L. Beduzzi, A. Geminardi, O. Smirnov
High Energy Astrophysical Phenomena
Fast radio burst - persistent radio source systems II. A faint PRS associated with the nearby FRB 20181030A?
D. Pelliciari, G. Bernardi, B. Margalit et al. (+10 more)
Persistent
radio sources (PRSs) are the continuum counterparts of fast
radio bursts (FRBs), the latter being extragalactic transients of millisecond duration and Jy-level flux density. An FRB-PRS system is thought to be a flaring magnetar surrounded by an highly magnetized, baryon-loaded nebula. We aim to constrain the size of 20181030A-S1, a new PRS candidate, potentially associated with the repeating FRB 20181030A. The latter is localized with $\sim 1'$ uncertainties in the outskirts of NGC 3252, which is a spiral
galaxy at a luminosity distance of $20$ Mpc. We report very long baseline interferometric (VLBI) observations using the European VLBI Network at $1.7$ GHz of this PRS candidate at an angular resolution of $20$ milliarcseconds. Our observations reveal the presence of an unresolved
radio source (20181030A-S1) at the position of the PRS candidate, confirming its compactness at milli-arcsecond angular scales. A fit to the position of the point-source yields a peak flux density of $280 \pm 30$ $\mu$Jy and a transverse physical size constrained to be $R < 0.5$ pc at $68\%$ confidence level (CL). This flux density converts to a spectral luminosity of $(9 \pm 1) \times 10^{25}$ erg s$^{-1}$ Hz$^{-1}$, $\sim 3$ orders of magnitude lower than confirmed PRSs, making 20181030A-S1 the closest and faintest PRS candidate known. Its low luminosity and modest rotation measure are consistent with the $L_\nu-$rotation measure (RM) relation followed by confirmed FRB–PRS systems, supporting a common physical origin in magnetar-powered nebulae. We show how a magnetized wind nebula powered by an initially weak ($B_\star \simeq 10^{15}$ G) and young ($t_{\rm age} \simeq 15 - 150$ yrs) magnetar can account for both the observed spectral luminosity and RM of the system. Other possible origin scenarios for 20181030A-S1, in the case in which it is unrelated to the FRB source, are also discussed.
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All authors D. Pelliciari, G. Bernardi, B. Margalit, B. D. Metzger, C. Nanci, L. Bruno, M. Pilia, L. Beduzzi, C. Spingola, C. Stanghellini, P. Esposito, A. Geminardi, M. Giroletti
High Energy Astrophysical Phenomena
Fast radio burst - persistent radio source systems I. A 1.2 GHz search and catalog definition
D. Pelliciari, L. Bruno, G. Bernardi et al. (+5 more)
We present new $1.26$ GHz observations of 24 fast
radio bursts (FRBs; 9 repeaters and 11 one-offs), conducted with the upgraded Giant Meter Wave
Radio Telescope (uGMRT) at arc-second angular scale resolution, and combined them with literature data to construct an extended sample of 75 sources with either persistent luminosity measurements or upper limits. Our catalog is complete down to a $10^{29}$ erg s$^{-1}$ Hz$^{-1}$ luminosity threshold, which corresponds to the value of the first-discovered PRS, associated with FRB 20121102. We detect compact
radio emission in six FRB fields, two of which are previously known PRSs and four are new candidates. The four new candidates are associated with three new repeating FRBs and one apparently one-off source. We computed the PRS occurrence using the whole catalog of 75 FRBs and found that PRSs more luminous than $10^{29}$ erg s$^{-1}$ Hz$^{-1}$ are rare. Unless otherwise stated, all uncertainties and upper limits are reported at the $95\%$ confidence level (CL). If we only consider confirmed PRSs, we find an occurrence of $f_{\rm all} = 0.06^{+0.09}_{-0.03}$, while including PRS candidates as well yields $f_{\rm all} = 0.14^{+0.22}_{-0.08}$. We also compute the PRS occurrence in the two classes of FRBs: repeating and non-repeating. In the conservative case, i.e., when none of the new PRS candidates are considered to be associated with their FRBs, we find no preferred association between the PRSs and FRB class, with an occurrence of $f_{\rm r} = 0.14^{+0.20}_{-0.09}$ for the sample of repeating FRBs and $f_{\rm nr} \leq 0.12$ for the sample of one-off sources. In the inclusive case, i.e., when all the new candidates are considered confirmed PRSs, we find $f_{\rm r} = 0.27^{+0.21}_{-0.14}$ and $f_{\rm nr} = 0.03^{+0.14}_{-0.02}$, with marginal ($90\%$ CL) evidence that PRSs are preferably associated with repeating FRBs.
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All authors D. Pelliciari, L. Bruno, G. Bernardi, M. Pilia, P. Esposito, L. Beduzzi, A. Geminardi, O. Smirnov
High Energy Astrophysical Phenomena
Empirical determination of the Galactic neutron star–black hole merger rate using StarTrack models
Terrence Pierre Jacques, D. R. Lorimer, Nihan Pol et al. (+2 more)
The discovery of a
pulsar in a binary system with a black hole would provide a unique laboratory for testing general relativity in the strong-field regime and offer vital constraints on massive
star evolution. We assess prospects for the detectability of such systems by utilizing the
radio pulsar population and survey models within the modeling package PsrPopPy and, as a proof of principle, two evolutionary models with different treatments of common-envelope phases from the stellar population synthesis code StarTrack. For these two models, assuming the
radio pulsar beaming model proposed by Tauris and Manchester and accounting for the effects of orbital motion on
pulsar detectability, we calculate upper limits on the number of
neutron star–black hole systems in the
Galaxy and the corresponding merger rate given the lack of any
radio-detected
pulsar–black hole binary systems in current
radio surveys. For the most constraining model, we find a Galactic merger rate $< 4.3~\text{Myr}^{-1}$ (at 95% confidence). These results are extrapolated to the expected horizon distance for the fifth LIGO observing run, leading to LIGO detection rate estimates that are consistent with the latest values reported by the LIGO-Virgo-KAGRA collaboration. Our results indicate that the increased sensitivity of FAST, MeerKAT, and DSA offers the best prospects yet for uncovering this elusive population.
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All authors Terrence Pierre Jacques, D. R. Lorimer, Nihan Pol, M. A. McLaughlin, K. Belczynski
Earth and Planetary Astrophysics
Correcting stellar contamination in transmission spectroscopy with contemporaneous monitoring: Application to GJ 1214 b
Ò. Porqueras-León, M. Perger, J. C. Morales et al. (+19 more)
Transmission spectroscopy has emerged as an essential tool for characterising the atmospheres of transiting
exoplanets. However, stellar surface inhomogeneities contaminate transmission spectra, posing a major challenge to high-precision observations such as those from the James Webb Space
Telescope (JWST). We develop and apply methods to correct for stellar contamination, improving the accuracy of
exoplanet atmospheric characterisation. We obtained coordinated multi-band photometry and high-resolution spectroscopy around JWST observations of GJ 1214 b and applied two frameworks: (i) a StarSim inversion, which infers stellar activity parameters from the monitoring data and propagates them to corrections; and (ii) UnSPOTTER, in which neural networks trained on StarSim simulations learn the mapping from monitoring data to corrections. Both frameworks agree within uncertainties and indicate that the JWST observations of GJ 1214 occurred at a favourable rotation phase with low stellar contamination. For UnSPOTTER, the inferred corrections can be constrained at approximately 15 ppm across the JWST wavelength range, implying post-correction residuals of the same order. If the same system were observed near activity maximum, the predicted contamination would be strongly chromatic and affect atmospheric
retrievals, highlighting the importance of coordinated monitoring and robust activity correction techniques. The two approaches are complementary but serve different roles. The inversion yields physically interpretable parameters and surface maps, whereas UnSPOTTER marginalises over surface-configuration degeneracies and provides tighter predictive corrections within its validated simulation domain. Our pipeline can be generalised to other active
stars: with multi-band and multi-technique monitoring around JWST visits, it can provide activity forecasts for scheduling and activity corrections.
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All authors Ò. Porqueras-León, M. Perger, J. C. Morales, I. Ribas, J. Blanco-Pozo, H. Tabernero, E. Herrero, E. Pallé, H. Parviainen, F. Murgas, C. Rodríguez-López, P. H. Hauschildt, A. Schweitzer, N.-E. Nèmec, D. Baroch, N. R. C. Gomes, G. Anglada-Escudé, J. Aceituno, N. Narita, A. Fukui, M. Mori, Y. Smolyarova
High Energy Astrophysical Phenomena
SN 2025qe: A case study of diversity in low-luminosity thermonuclear explosions
Hrishav Das, Anirban Dutta, Devendra K. Sahu et al. (+3 more)
We present optical photometric and spectroscopic observations of SN 2025qe, a Type Iax
supernova in IC 0529, monitored from $-10$ to $+150$ rest-frame days relative to $g'$-band maximum using the GROWTH-India and the Himalayan Chandra
Telescopes. SN 2025qe reaches a peak $g'$-band absolute magnitude of $M_{g'} \approx -16.16 \pm 0.15$ mag, placing it in the sparsely sampled luminosity gap between the brightest and faintest members of the SNe Iax class. The multiband light curves show pronounced wavelength-dependent broadening at late times, with the redder bands remaining brighter than in other SNe Iax. Semi-analytical (Arnett) modeling of the pseudobolometric light curve yields a synthesized $^{56}$Ni mass of $0.02\,M_\odot$, an ejecta mass of $0.45\,M_\odot$, and a kinetic energy of $7.0\times 10^{49}$ erg. Three-dimensional pure-deflagration models of Chandrasekhar-mass carbon-oxygen white dwarfs reproduce the peak luminosity and $^{56}$Ni yield but underpredict the slow, red post-maximum decline; models including energy input from a bound remnant better match the late-time
evolution, especially in the red bands. We model early-time spectra using TARDIS with a modified deflagration model and identify late-time spectral features using syn++. We qualitatively try to explain the persistent red-band flux with a two-component ejecta structure comprising a dense inner region, possibly including a bound remnant, and a density-enhanced outer shell that sustains redder emission. Together, the photometric and spectroscopic properties of SN 2025qe highlight the diversity of ejecta structure and
evolution among SNe Iax with similar peak luminosities, emphasizing the need for detailed observations and modeling of their ejecta.
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All authors Hrishav Das, Anirban Dutta, Devendra K. Sahu, G.C. Anupama, Prathamesh S. Kadam, Vishwajeet Swain
Cosmology and Nongalactic Astrophysics
Tide-and-Seek: Anisotropic scale-dependent bias in the Lyman-alpha forest and designer samples
Yong Sheng Yap, William R. Coulton and Vid Iršič
Searches for primordial non-Gaussianity are powerful ways of learning new information about the early Universe. Observing primordial signals in the late Universe is challenging as, in general, it is difficult to disentangle the small, primordial signatures from the complex physics that describes the distribution of
galaxies and large-scale
cosmic structures. We demonstrate that scale-dependent bias from primordial non-Gaussianity with non-trivial directional dependence in the squeezed limit (also known as anisotropic primordial non-Gaussianity) can arise in a much larger class of tracers than previously considered. This is a smoking gun signature of primordial Universe physics that cannot be mimicked by late-Universe processes. We demonstrate this explicitly with simulations of the Lyman-$\alpha$ forest and
halos selected through their projected shape. The former is a standard cosmological probe and standard analyses could be simply extended to constrain this. The latter provides an interesting new approach: design samples with strong selection effects to provide new sensitivity to primordial physics. As a demonstration of these concepts, we apply this method to BOSS DR12 data, finding no evidence of anisotropic non-Gaussianity.
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High Energy Astrophysical Phenomena
JWST unveils a dust-obscured supernova associated with a gamma-ray burst
B. Schneider, A. J. Levan, N. Sarin et al. (+22 more)
Recent observations have challenged the duration-based classification of gamma-ray bursts (GRBs), making the detection of an associated
supernova (SN) or kilonova crucial for conclusively identifying their progenitors. We investigate the origin of GRB 240825A at $z=0.659$, whose
prompt emission gave conflicting indications of a merger or collapsar origin and for which no SN was detected in deep ground-based observations. We analyze JWST/NIRSpec observations obtained 66.5 days (40.1 days in the rest frame) after the burst. We identify a SN signal using a pixel-by-pixel decomposition of the 2D spectrum and isolate it by jointly modeling the host and transient emission. We constrain the line of sight extinction from the afterglow spectral energy distribution and characterize the host through broadband photometry and nebular emission lines. Despite a dusty line of sight ($A_V=1.37\pm0.08$ mag), with tentative evidence of a 2175 Å bump, and a bright host
galaxy ($M_B=-20.5$ AB mag), we identify a point-like source at the GRB position with broad spectral features similar to those of SN 1998bw. The SN contributes $\sim$10-15% of the NIRSpec flux and would contribute only $\sim$1% of the total flux in a ground-based optical image at the same epoch. Its extinction-corrected luminosity is comparable to SN 1998bw, although it remains sensitive to the host subtraction and template assumptions. The host is an extended, dusty,
star-forming
galaxy with $\log(M_\star/M_\odot)=10.12\pm0.05$, SFR $=5.88\pm1.60\,{\rm M_\odot\,yr^{-1}}$, and a super-solar
metallicity of $12+\log({\rm O/H})=8.87\pm0.04$, above the
metallicity typically observed for collapsar GRB hosts. The detection of a dust-obscured SN firmly establishes the massive-
star origin of GRB 240825A and shows that JWST can uncover SNe in dusty, chemically enriched environments that were previously largely inaccessible.
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All authors B. Schneider, A. J. Levan, N. Sarin, N. A. Rakotondrainibe, B. P. Gompertz, V. Buat, J. T. Palmerio, D. B. Malesani, A. de Ugarte Postigo, A. Martin-Carrillo, A. Rossi, V. D'Elia, M. De Pasquale, D. Hartmann, P. Jakobsson, E. Le Floc'h, P. O'Brien, E. Pian, G. Pugliese, A. Raidani, R. Salvaterra, J. Sollerman, N. R. Tanvir, S. D. Vergani, D. Watson
Earth and Planetary Astrophysics
K-dwarf starspot hunters: how to directly characterize spot and faculae properties with UV-IR panchromatic transit spectra
Joanna K. Barstow, Caitlyn Cullen, Yvonne Unruh et al. (+7 more)
Transmission spectroscopy of
exoplanets provides an important window into their atmospheric composition, structure and dynamics, especially in the JWST era. As the quality of the observational data and therefore the precision of our constraints improves, we become increasingly sensitive to sources of systematic bias in our models and observations. One significant example of this is the Transit Light Source Effect, in which heterogeneous features in the stellar photosphere - spots and faculae - imprint additional spectral signatures onto
exoplanet transmission spectra. The effects of this stellar contamination must be accounted for or removed in order to accurately recover the
planet's atmospheric properties. Including parameterized models of spots and faculae within spectral
retrieval analysis is increasingly adopted as a solution to this problem, but is limited by the accuracy of models of stellar spectra. In this paper, we outline an observational strategy combining simultaneous data from JWST and the Hubble Space
Telescope that would enable us to further constrain these models. We perform synthetic
retrievals to demonstrate how we could constrain starspot and faculae parameters; we test the impact of using different model spectra in the
retrieval; and we consider the impact of variable stellar activity on coadding transits to achieve the desired signal-to-noise. We find that ultraviolet and optical wavelengths are key for breaking degeneracies between stellar contamination and planetary parameters.
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All authors Joanna K. Barstow, Caitlyn Cullen, Yvonne Unruh, Hannah Wakeford, Eva-Maria Ahrer, Lili Alderson, Charlotte Fairman, Ulrich Kolb, Nikole Lewis, Cinta Vidante
Instrumentation and Methods for Astrophysics
Accelerating massive ensembles of ordinary differential equations
Lawrence Berry, Will Handley, Oliver Hahn et al. (+1 more)
Solving large ensembles of small, independent ordinary differential equations (ODEs) is a common task in computational science and engineering, arising for example in
Bayesian parameter estimation, Monte Carlo uncertainty quantification, and the integration of uncoupled physical systems such as the linearised Einstein-Boltzmann equations of cosmology. Modern graphics processing units (GPUs) with thousands of cores are well suited to such parallel workloads, but realising this potential requires careful
attention to GPU-specific architectural constraints. We present modax, a Python library of GPU-accelerated ODE solvers specifically optimised for solving large ensembles of low-dimensional, independent problems. Our solvers are compatible with the JAX ecosystem but are written in a low-level, thread-based programming paradigm better suited to ensembles of highly divergent trajectories than their pure-JAX counterparts.
Benchmarks on the Lorenz, Robertson and van der Pol
lattice systems compare modax against diffrax, DiffEqGPU$.$jl and torchdiffeq across ensemble size, dimensionality, and trajectory divergence. Our explicit Tsit5 solver achieves 30x speed-up over diffrax on Lorenz systems, and our implicit Rodas5P solver achieves over 700x speed-up on Robertson systems, demonstrating the superiority of linearly implicit Rosenbrock-Wanner methods on GPUs. Our implicit solver scales well to higher dimensions thanks to the use of sparsity-exploiting techniques and data structures. We conclude by applying modax to three examples from the field of cosmology -
Bayesian parameter estimation from primordial abundances, Monte Carlo uncertainty quantification of the global 21cm signal, and the computation of uncoupled
Fourier modes in the primordial power spectrum - and demonstrate significant efficiency improvements in our ability to model physical phenomena described by low-dimensional (<200D) ODEs.
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All authors Lawrence Berry, Will Handley, Oliver Hahn, Nils Schöneberg
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
The LZ event with a two-state dark matter halo
Vinicius Oliveira
The LUX-ZEPLIN (LZ) experiment has reported a single nuclear-recoil candidate at $E_R \simeq 248$keV. LZ interprets it in terms of inelastic dark matter that scatters endothermically from its ground state, $\chi_1 N \to \chi_2 N$. In pseudo-Dirac models the excited state $\chi_2$ can survive to the present day, and exothermic scattering, $\chi_2 N \to \chi_1 N$, is then also open. The published LZ intervals do not describe this case. We rebuild the LZ statistical inference and validate it against the published intervals. We then apply it to a
halo that contains a fraction $f$ of $\chi_2$. For $f \gtrsim 10^{-5}$–$10^{-2}$, depending on the mass splitting, the exothermic contribution dominates. For $f=1/2$ the cross section required by the candidate drops by factors of $80$ to $1.6\times10^4$ for $\delta = 250$–$350$~keV, and the kinematic cutoff of the endothermic signal disappears. A
benchmark that explains the event with $\chi_1$ alone lies a factor of $30$ above the upper limit when half of the
halo is $\chi_2$.
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Earth and Planetary Astrophysics
JWST NIRSpec G395H Transmission Spectra of Two Similar Sub-Neptunes in the TOI-125 System
Yiwei Chai, Néstor Espinoza, Chloe Fisher et al. (+10 more)
The James Webb Space
Telescope (JWST) has enabled the first in-depth characterisations of sub-Neptune atmospheres, revealing a diversity of chemical compositions and cloud properties that challenge current models. Multi-
planet systems provide an opportunity to compare planetary atmospheres while controlling for formation conditions within the same protoplanetary disk. We present JWST NIRSpec G395H 3-5 um observations of two similarly-sized sub-Neptunes orbiting a sun-like
star within the TOI-125 system: TOI-125 b ($P=4.65$ d, $R_p=2.7~R_\oplus$, $M_p=10~M_\oplus$, $T_\mathrm{eq}=1100$ K) and TOI-125 c ($P=9.15$ d, $R_p=2.85~R_\oplus$, $M_p=6.8~M_\oplus$, $T_\mathrm{eq}=825$ K), comprising of one full transit of TOI-125 b but only 70% of TOI-125 c's transit due to larger than predicted TTVs. We obtain precise R~100 transmission spectra for both
planets, with median errorbars of 50 ppm for TOI-125 b and 85 ppm for TOI-125 c. Atmospheric
retrievals are compatible with a ~150x solar
metallicity atmosphere or clouds above ~3 mbar for TOI-125 b, and a ~100x solar
metallicity atmosphere or clouds above ~10 mbar for TOI-125 c. Our results may support recent evidence for metal enrichment in sub-Neptunes, while also further complicating the proposed trend in atmospheric feature size with
planet temperature. However, shorter wavelength follow-up observations of both
planets are needed to establish whether their spectra are truly muted or feature-rich, with implications for the nature of sub-Neptunes around sun-like
stars.
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All authors Yiwei Chai, Néstor Espinoza, Chloe Fisher, Erik Meier Valdes, Matthew Hooton, Brett Morris, Natalie H. Allen, Adam J. Burgasser, Brice-Olivier Demory, Amélie Gressier, Kevin Heng, Mercedes López-Morales, Meng Tian
Astrophysics of Galaxies
The abundance and emission of PAHs from the local to early Universe
Massimiliano Parente, Desika Narayanan, Paul Torrey et al. (+8 more)
We present the first large-volume cosmological simulation of
galaxy evolution with a model for the abundance and luminous emission of Polycyclic Aromatic Hydrocarbons (PAHs) across a wide range of
cosmic time ($0 < z \lesssim 6$). The simulation is built on a semi-analytic model (SAM) that includes a treatment of dust size distribution, with PAHs being identified with the smallest carbonaceous grains ($< 15$ A) residing in the diffuse ISM of
galaxies. PAH emission is computed by post-processing the simulation output with the radiative transfer code GRASIL. In our model, where
stars only inject large grains, the PAH abundance emerges from the growth and shattering of dust grains in the ISM, naturally reproducing the observed correlation between the PAH mass fraction ($q_{\rm PAH}$) and both
metallicity and specific
star formation rate (sSFR). We derive a relation to infer $q_{\rm PAH}$ from $L_{\rm PAH}$, $L_{\rm IR}$, and sSFR, with a relatively small scatter (a factor of $\approx 1.3$). Simulated PAH emission correlates well with key
galaxy properties such as SFR and molecular gas content, and reproduces observational constraints. Taken together, these results support the viability of a top-down formation scenario for PAHs. We extend our model predictions to higher
redshifts, which can be exploited for future missions such as PRIMA. This work is a significant step toward leveraging PAH observations as a tool for studying
galaxy evolution.
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All authors Massimiliano Parente, Desika Narayanan, Paul Torrey, Gian Luigi Granato, Brandon S. Hensley, Jed McKinney, Alexandra Pope, Gergö Popping, Irene Shivaei, Laura Silva, J.D.T. Smith
Astrophysics of Galaxies
Precise C-N-O Abundances of Individual Galaxies in the First Billion Years from Ultra-Deep, Rest-UV-to-Optical JWST Spectroscopy
Raunaq Singh Rai, Guido Roberts-Borsani, Ryan Sanders et al. (+8 more)
We present ultra-deep JWST/NIRSpec $R\sim1000$ spectroscopy of nine
star-forming
galaxies at $z=6.0-8.3$ in the GOODS-N field, drawn from the Origins of Metal Enrichment in
Galaxies at
cosmic dAwn (OMEGA) survey. Paired with ancillary ultra-deep G140M observations, the G395M integrations from OMEGA yield continuous rest-frame UV-to-optical coverage and the full suite of diagnostics needed for precise characterisations and measures of the chemical abundances of these systems. Crucially, the auroral [O\,{\scriptsize III}]\,$\lambda$4363 line is detected in every
galaxy, enabling the determination of electron temperatures and direct oxygen abundances of $12+\log(\mathrm{O/H})=7.14-8.18$, independent of strong-line calibrations that dominate systematics at these
redshifts. We couple direct oxygen abundances with measurements of rest-frame UV emission-line strengths and ratios to infer the physical properties of our sample. Most importantly, we trace the relationship between oxygen abundance and both C/O and N/O abundance ratios with high fidelity, demonstrating robustly that $z=6.0-8.3$
galaxies follow the local trend in C/O vs. O/H, and that inferences regarding N/O are sensitive to the choice of rest-frame UV (\niv] or \niii]) or optical ([\nii]) tracers. This pilot study demonstrates the power of combining ultra-deep JWST/NIRSpec $R\sim1000$ rest-frame UV and optical spectroscopy, which now requires statistical samples to uncover the nebular properties of the full population of $z\geq 6$
star-forming
galaxies.
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All authors Raunaq Singh Rai, Guido Roberts-Borsani, Ryan Sanders, Alice E. Shapley, Leonardo Clarke, Pascal A. Oesch, Daniel Schaerer, Rui Marques-Chaves, Romain A. Meyer, Emma Giovinazzo, Shreya Karthikeyan
Instrumentation and Methods for Astrophysics
Refactoring the SIXTE simulator: Towards a more modular code base
Christian Kirsch, Maximilian Lorenz, Lea Dauner et al. (+7 more)
The SIXTE (SImulation of X-ray
TElescopes) software is a general end-to-end simulation toolkit for X-ray observations, covering the full observation process from source
photon generation to detector readout and the production of high-level output files. It is the official simulator for existing and future X-ray missions, such as eROSITA, NewAthena, THESEUS and AXIS. Originally being designed as a simulator for eROSITA, the addition of new instrument and
telescope types over several years has made the original code base increasingly difficult to maintain. As such, we have refactored the code, changing
languages from C to C++ and switching to a more modular software design to facilitate the implementation of new models. This proceeding highlights some of the design choices used during the refactoring as well as its effects on maintenance and new feature development one year after release of the refactored code base.
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All authors Christian Kirsch, Maximilian Lorenz, Lea Dauner, Esin G. Gülbahar, Karan Pal, Neo Reinmann, Jakob Stierhof, Philipp Thalhammer, Thomas Dauser, Jörn Wilms
Astrophysics of Galaxies
Diverse Metallicities in Protoclusters at $z \sim 3.4$ detected by Deep Learning
Yoshihiro Takeda, Nobunari Kashikawa, Kei Ito et al. (+12 more)
We present spectroscopic follow-up observations with Subaru/MOIRCS of four protocluster candidate regions identified by the deep-learning model PCFNet. In three candidate regions, we confirm four protoclusters at $z =$ 3.316, 3.403, 3.408 and 3.425, exhibiting
galaxy density peaks over five times the uniform distribution. The detection rate of confirmed members aligns with PCFNet's predictions, underscoring its effectiveness. Analysis of spectral energy distributions (SEDs), incorporating up to ten photometric bands $(uu^*grizyJHK)$, reveals that protocluster members lie on the
star-formation main sequence. The masses of the most massive
halos in the protoclusters are estimated from the most massive stellar mass of the member
galaxies, yielding $\log M_\mathrm{halo}/M_\odot=12.4$-$12.8$, which are consistent with those at this
redshift predicted by cosmological simulations and are comparable to those of the progenitors of typical local clusters ($M_\mathrm{halo}^{z=0}\sim10^{14}M_\odot$). Using the Voronoi Tessellation Monte Carlo technique based on the probability of protocluster membership from PCFNet, we find that our protoclusters exhibit a significantly higher SFRD than the
cosmic SFRD at $z\sim3.4$. Based on the [Oiii]/H$\beta$ emission line ratio, two protoclusters show marginally ($1.4$-$2\sigma$) higher average
metallicities than the field, while the other protoclusters are statistically consistent with the field. These diverse
metallicities highlight the environmental impact within protoclusters detected by PCFNet, likely reflecting the complex opposing interplay between metal-rich gas recycling and metal-poor gas inflow, which may depend on the surrounding environment of each protocluster. This work demonstrates PCFNet's capability to unveil diverse samples of high-
redshift protoclusters, paving the way for a more comprehensive understanding of their role in
galaxy evolution.
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All authors Yoshihiro Takeda, Nobunari Kashikawa, Kei Ito, Jun Toshikawa, Mariko Kubo, Rieko Momose, Yongming Liang, Takehiro Yoshioka, Junya Arita, Hiroki Hoshi, Shunta Shimizu, Hisakazu Uchiyama, Satoshi Kikuta, Ryo Emori, Kentaro Koretomo
Instrumentation and Methods for Astrophysics
Source–Line Associations in JWST/NIRSpec Dense-Shutter Spectroscopy
Zihao Wu, Daniel J. Eisenstein, Francesco D'Eugenio et al. (+9 more)
We demonstrate the feasibility of source–line association in JWST/NIRSpec dense-shutter spectroscopy, with $\sim$2000 sources observed simultaneously per pointing regardless of spectral overlap. While JWST wide-field slitless spectroscopy (WFSS) can disentangle overlapping spectra using two grisms with perpendicular dispersion directions, NIRSpec can achieve this using gratings with different dispersions. Compared with WFSS, NIRSpec dense-shutter spectroscopy offers substantially higher sensitivity and broader wavelength coverage. We develop a
Bayesian framework that combines cross-dispersion offsets, wavelength consistency, and changes in relative line positions between gratings to jointly determine source associations and
redshifts. We test the method using mock observations based on the observed source distribution and emission-line fluxes from the JWST Advanced Deep Extragalactic Survey (JADES), accounting for the NIRSpec optical model, MSA operability, measurement noise, false-positive detections, and bad pixels. Although the spectral traces overlap extensively, fewer than 0.5% of the simulated emission lines are blended with another line on the detectors in NIRSpec grating spectroscopy. Applying our method to these simulations, we obtain
redshifts, at an accuracy of 98%, for the $\sim$1800 sources that have detectable emission lines, of which $\sim$1500 are classified as confident and are 99.9% accurate. We further investigate how the association accuracy depends on the number of grating configurations. By combining high multiplexing, high sensitivity, and broad wavelength coverage, NIRSpec dense-shutter spectroscopy enables efficient, highly complete spectroscopic surveys for the high-
redshift Universe.
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All authors Zihao Wu, Daniel J. Eisenstein, Francesco D'Eugenio, Erica Nelson, Benjamin D. Johnson, Andrew J. Bunker, Zhiyuan Ji, Pierluigi Rinaldi, Brant Robertson, Sandro Tacchella, Christopher N. A. Willmer, Joris Witstok
Solar and Stellar Astrophysics
V405 Draconis: A Deep Contact Binary with a Tertiary Companion and a Quadruple System Candidate
Maksym Yu. Pyatnytskyy and Ivan L. Andronov
We continued our analysis of the O-C diagram of the EW-type eclipsing binary V405 Dra using recently available data. We refined the orbital parameters of the third body responsible for the short-period oscillations in the O-C curve, obtaining $P_3=513.12(20)$ d, $a_{12}\sin i_3=0.3862(15)$ AU, and $e_3=0.1690(48)$. Assuming a total mass of $1.56$ $M_\odot$ for the eclipsing binary, the minimum mass of the third body is estimated to be about $0.5$ $M_\odot$. We also investigated the complex long-term O-C trend and found that it may be partially explained by the light-time effect caused by a possible fourth body, with a characteristic period of about 23.5 yr and a minimum mass of about $0.9$ $M_\odot$. However, the fourth-body model cannot fully reproduce the observed long-term variation, particularly the earliest data, and the nature of part of the long-term trend remains unexplained.
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Astrophysics of Galaxies
Extreme MgII Emission in Recently-Quenched Galaxies: A New Sample of Intermediate-Redshift Post-Starburst Quasars from the DESI Early Data Release
Margaret E. Verrico, Aayan Verma, K. Decker French et al. (+8 more)
Post-starburst
galaxies are
galaxies which have recently and rapidly shut off
star formation. AGN activity is often invoked to explain this rapid quenching, but most post-starburst selection methods select against optical AGN, motivating searches for "post-starburst
quasars." We present DESI observations of ten post-starburst
quasars with significant MgII emission ($L_{\text{MgII}} \geq 3 \times 10^{41}$ erg/s). This is the first sample of post-starburst
quasars to be selected from a post-starburst
galaxy parent sample rather than a
quasar catalog.
Quasars make up $4.6^{+1.6}_{-1.2}\%$ of the post-starburst parent sample at $0.49 \leq z \leq 1.39$. Using multiwavelength AGN diagnostics, we find that $26^{+3.0}_{-2.8}\%$ of post-starbursts in the parent sample host AGN. We find that post-starburst selection methods are biased against AGN with $\text{L}_{\text{Bol}}\gtrsim10^{45} \textrm{erg s}^{-1}$, potentially removing the
quasars responsible for driving outflows that aid in quenching. Finally, we find that 9/10 post-starburst
quasars in our sample have no detected broad H$\beta$, similar to so-called "MgII emitters" that may be the remnants of fading
quasars; if confirmed, these objects suggest a link between post-starburst
galaxies and variable AGN. Our new sample of post-starburst
quasars provides a link between previously reported local and high
redshift post-starburst
quasars during the epoch when
star formation throughout the universe was declining.
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All authors Margaret E. Verrico, Aayan Verma, K. Decker French, David J. Setton, Omar Almaini, Jenny E. Greene, Stephanie LaMassa, Yuanze Luo, Pallavi Patil, Kate Rowlands, Dharlenny Soto
Astrophysics of Galaxies
ViCTORIA project: A pilot study of the M49 region in the Virgo cluster in polarisation
A. Spasic, A. Benati, M. Brüggen et al. (+7 more)
Large-scale
magnetic fields permeate the Intracluster Medium (ICM) of
galaxy clusters. Understanding these fields gives an insight into the origin of
cosmic magnetic fields and the interaction of cluster
galaxies with the ICM. Using MeerKAT observations of the Virgo cluster as part of the ViCTORIA project, we probe
magnetic fields via Rotation Measure (RM) synthesis. The aim of this work is to characterise the
magnetic fields in and around the infalling group M49 in the Virgo cluster. We will probe the interaction of M49 with its surrounding medium through its imprint on the polarised emission and Faraday rotation. We use L-band MeerKAT data in full polarisation calibrated with the ViCTORIA MeerKAT Survey (ViMS) pipeline, which is designed for the calibration, imaging, mosaicking and RM Synthesis of the fields in the Virgo cluster, to achieve high-fidelity reconstruction of, both, total intensity and polarised emission. We analyse the background sources of the cluster for potential local changes in the
magnetic field, by calculating the RM distribution. In the final polarised image, consisting of four pointings of 45 min, we reach a noise level of $23.3 \mu \textrm{Jy/beam}$. We detect 101 background sources in the $\sim 2.5\, \textrm{deg}^2$ region around M49, corresponding to a source density of 40 sources/$ \textrm{deg}^2$. Across the $112\, \textrm{deg}^2$ observations of the Virgo cluster, this implies a total number of 4000 polarised sources. In M49 we find structured, diffuse polarised emission extending in the direction of the total intensity
radio tails. A higher polarisation fraction across the upper edge of the source indicates the effect of
magnetic field draping. Around M49 we find a larger RM scatter (at $3.8\sigma$) in the wake of M49 compared to the region in front of it. This can inform the modelling of the
turbulence created by galactic motions.
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All authors A. Spasic, A. Benati, M. Brüggen, H. W. Edler, F. De Gasperin, V. Gustafsson, P. Serra, A. Bonafede, A. Boselli, H. McCall
Cosmology and Nongalactic Astrophysics
LISA bright sirens as a tiebreaker among cosmologies in tension
M. F. A. Medeiros, F. C. Carvalho and L. L. Sales
Gravitational waves from massive black hole binaries detected by LISA will deliver luminosity distances without any astrophysical calibration, offering a probe of the expansion history independent of the
cosmic distance ladder. Rather than asking how tightly LISA will constrain a single fiducial cosmology, we ask which of several mutually discrepant present-day cosmologies a future LISA
dataset would render most self-consistent. We build mock catalogues of LISA bright sirens under three fiducial cosmologies drawn from
datasets that participate in the current $H_0$ discrepancy (Planck 2018, Union3 and Pantheon+SH0ES), with a self-consistent error budget from instrumental noise, weak
lensing and host peculiar velocities. We compare the posterior from the simulated LISA data alone with that of a real-data combination of Type Ia
supernovae, DESI baryon acoustic oscillations,
cosmic chronometers and the compressed Planck 2018 CMB, and quantify their internal tension in the $(H_0,\Omega_m)$ plane, crossing each fiducial with three SN Ia compilations. The fiducial drives the tension, from $2.08\sigma$ to well beyond $5\sigma$, while the
supernova compilation changes it by at most $1.2\sigma$. The discriminating power is strongly asymmetric: a Pantheon+SH0ES universe is inconsistent with every background we test, at a significance far in excess of $5\sigma$ and still at $3$-$5\sigma$ for the $10$-$20$ events expected from recent population models, whereas the Planck 2018 and Union3 fiducials, which differ by only $0.24$ km/s/Mpc in $H_0$, cannot be separated by any catalogue size. LISA bright sirens are therefore a sharp arbiter of the Cepheid-calibrated scenario and, on this error budget, silent between the other two.
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Astrophysics of Galaxies
The 2MIG isolated AGNs – 4. Linking hot-dust reverberation to spectroscopically predicted BLR scales in IC~5287 and Mrk~845
I.O. Izviekova, I.B. Vavilova, O.V. Kompaniiets et al. (+2 more)
We investigate the relation between directly measured hot-dust reverberation scales and spectroscopically predicted broad-line region (BLR) scales in the isolated Seyfert
galaxies IC~5287 and Mrk~845 (MCG+09-25-022), combining ZTF optical light curves, WISE/NEOWISE monitoring, and archival SDSS spectroscopy. Both
nuclei show BWB optical variability, RWB MIR behaviour, and delayed MIR responses consistent with circumnuclear dust reprocessing. For IC~5287, interpolated cross-correlation function analysis with flux-randomisation/random-subset-selection uncertainties yields a rest-frame W1 delay of $106_{-39}^{+24}$~d, corresponding to $0.089_{-0.033}^{+0.020}$~pc. The median W2 response occurs at a longer delay, but the lag distributions overlap substantially. The SDSS decomposition reveals strong host dilution and BLR reddening, $E(B-V)_{\rm BLR}=0.612_{-0.066}^{+0.067}$~mag. Applying the same colour excess to the AGN continuum as an illustrative scenario increases the predicted H$\beta$ BLR lag from approximately 4.8 to 11.7~d and reduces the dust-to-predicted-BLR radius ratios from approximately 20–25 to 8–10. For Mrk~845, transfer-function modelling gives a rest-frame W1 delay of $157_{-8}^{+19}$~d, corresponding to $0.132_{-0.007}^{+0.016}$~pc. Its W2 response occurs at a longer delay, with $P(\tau_{\rm W2}>\tau_{\rm W1})=0.963$, supporting wavelength-dependent hot-dust structure. The SDSS spectrum shows more moderate BLR reddening, $E(B-V)_{\rm BLR}=0.197_{-0.039}^{+0.046}$~mag. The comparatively large dust-to-predicted-BLR radius ratios in both
galaxies therefore primarily reflect the spectroscopically predicted BLR scales. These results emphasise the need to distinguish directly measured dust reverberation radii from BLR radii inferred from single-epoch spectroscopy when interpreting the BLR–dust hierarchy.
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All authors I.O. Izviekova, I.B. Vavilova, O.V. Kompaniiets, O. Zamora, R. Clavero
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
A Cuscuton Representation of the Loop Quantum Cosmology Bounce
Niayesh Afshordi and Kristina Giesel
Loop
Quantum Cosmology (LQC) replaces the big bang singularity of the homogeneous universe by a bounce, usually described by the modified Friedmann equation $H^2=\rho(1-\rho/\rho_c)/(3M_p^2)$. We show that this background dynamics follows from a local cuscuton effective theory, whose scalar equation is a constraint rather than a wave equation. One way to establish this is to write the cuscuton in terms of an angular coordinate $\theta$, identified with the LQC polymerization angle $2\lambda b$. Its constraint gives $H\propto\sin\theta$, while the Einstein constraint gives $\rho=\rho_c\sin^2(\theta/2)$, exactly reproducing the LQC bounce. To our knowledge, this is the first closed-form, local, generally covariant realization of the exact standard flat-FLRW LQC background dynamics for minimally coupled matter satisfying null energy condition, without introducing additional local dynamical degrees of freedom. A branchwise Legendre transformation establishes a canonical equivalence between the clock-gauge-fixed homogeneous mimetic system in the case of vanishing mimetic dust energy density and the cuscuton systems. It selects the constant-tension cuscuton coordinate $\Theta=\sin\theta-\theta$, while $\theta$ retains its interpretation as the LQC polymerization angle. This equivalence does not establish agreement of the inhomogeneous theories or their perturbations. The angular action also admits an explicit branched $f(K)$ representation, where $K$ is the mean extrinsic
curvature of spatial hypersurfaces. The construction is therefore an effective covariant representation of the LQC holonomy correction, not a derivation from full loop
quantum gravity.
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Astrophysics of Galaxies
Probing Spatial Variations in IGM Transmission: Higher Ly$\alpha$ Visibility in an H$\alpha$-Selected Galaxy Overdensity at $z\simeq6.2$
Shunta Shimizu, Nobunari Kashikawa, Junya Arita et al. (+13 more)
The visibility of Ly$\alpha$ emission during the epoch of reionization depends on both
galaxy properties and the transmission of Ly$\alpha$
photons through the intergalactic medium (IGM). Using JWST/NIRCam F470N imaging, we identify a prominent projected overdensity of H$\alpha$ emitters (HAEs) at $z\simeq6.2$ in CEERS field. We use Subaru/HSC NB872 imaging to measure their Ly$\alpha$ fluxes and compare the Ly$\alpha$ visibility of
galaxies within $2'$ of the density center with that of
galaxies outside this region. The Ly$\alpha$-emitter (LAE) fraction is $0.41^{+0.15}_{-0.14}$ in the inner region and $0.27^{+0.19}_{-0.15}$ in the outer region. Stacking the H$\alpha$ and Ly$\alpha$ images gives median Ly$\alpha$ escape fractions of $0.100^{+0.091}_{-0.053}$ and $0.063^{+0.130}_{-0.063}$ in the inner and outer regions, respectively. Both measures indicate higher Ly$\alpha$ visibility in the inner region, although only at modest significance. HAEs closer to the density center are systematically more massive and have redder UV slopes, which instead favor lower Ly$\alpha$ escape. The environmental difference in Ly$\alpha$ visibility is therefore difficult to explain solely by variations in underlying
galaxy population. Our results are consistent with reduced Ly$\alpha$ attenuation through a more highly ionized IGM in the overdense region, as expected if large H\,ii bubbles preferentially form around such
galaxy overdensities. The wide-field LAE distribution provides complementary support for this scenario, as the HAE-defined density center coincides with the strongest LAE overdensity across the $1.4\,{\rm deg}^2$ HSC field. These findings highlight the importance of spatial variations in IGM attenuation in shaping Ly$\alpha$ visibility near the end of reionization.
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All authors Shunta Shimizu, Nobunari Kashikawa, Junya Arita, Ryo Emori, Kohei Inayoshi, Akio K. Inoue, Kei Ito, Satoshi Kikuta, Kentaro Koretomo, Mariko Kubo, Yongming Liang, Rieko Momose, Kentaro Nagamine, Masafusa Onoue, Rhythm Shimakawa, Hisakazu Uchiyama
Instrumentation and Methods for Astrophysics
Stellar interferometry with a K-band integrated optics beam combiner instrument at the CHARA Array - I. First on-sky fringes for CHARIOT
Aline N. Dinkelaker, Kévin Barjot, Nic Scott et al. (+8 more)
We present the instrument description and the first on-sky observations for the new CHara ARray Integrated Optics Testbench (CHARIOT) at the CHARA Array. CHARIOT is a 2-
telescope proof-of-concept instrument that utilises a fibre-connectorised beam combiner fabricated by ultrafast
laser-inscription in Infrasil quartz glass, which presents low-OH contamination and high transparency over the whole K-band. With its fibre-connected architecture, CHARIOT is designed as a plug-and-play testbed instrument to test and validate fibred astrophotonic components on-sky. At this point, CHARIOT is able to measure raw fringe squared visibilities with a sub-1% precision for
stars with K-mag<2. Under poor to moderate seeing conditions, the current limiting magnitude for fringe detection is K-mag = 5.212 (HD210824). These results demonstrate that CHARIOT's performance is already comparable to the former JouFLU instrument. With additional improvements, the limiting magnitude could be extended and the precision for fainter
stars improved. The successful on-sky demonstration paves the way for a new high precision K-band beam combiner instrument at the CHARA array.
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All authors Aline N. Dinkelaker, Kévin Barjot, Nic Scott, Aurélien Benoît, Narsireddy Anugu, Alyssa V. Mayer, Jacopo Siliprandi, Robert R. Thomson, Kalaga Madhav, Gail Schaefer, Lucas Labadie
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
Parameter degeneracy and information loss in inverse flavor mapping for high-energy astrophysical neutrinos
Zi-Qiang Chen, Zhi-zhong Xing and Ye-Ling Zhou
Given a high-energy astrophysical
neutrino flux, its source flavor ratios $\eta = \{\eta^{}_e, \eta^{}_\mu, \eta^{}_\tau\}$ are correlated with the ones $f = \{f^{}_e, f^{}_\mu, f^{}_\tau\}$ measured at a
neutrino telescope via $f = P \eta$, where the elements of $P$ consist of four lepton flavor mixing parameters. But realistic inverse flavor mapping $\eta = P^{-1} f$ encounters unavoidable parameter degeneracy and information loss, especially in or near the $\det P = 0$ limit allowed by current
neutrino oscillation data. In this work we explore the parameter correlation condition for $\det P = 0$ including the $\mu$-$\tau$ reflection
symmetry case, formulate the corresponding constraints on $f^{}_e$ and $f^{}_\mu$ versus $\eta^{}_e$ and $\eta^{}_\mu$, and illustrate to what extent the source flavor distribution can be mapped by using the recent IceCube all-sky
neutrino flux data ranging from 5 TeV to 10 PeV under the assumption that the relevant sources have a common flavor composition.
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Solar and Stellar Astrophysics
A First Global Full-Vector Coronal Magnetic Field Inference Using MLSO CoMP and UCoMP Observations
Alin Razvan Paraschiv, Zihao Yang, Daniela Adriana Lacatus et al. (+1 more)
Building on recent advances in coronal spectropolarimetry, seismology, and
magnetic-field inferences of Z. Yang et al. (2024) and A. R. Paraschiv (2026), we present the first application of the CLEDB IQUD inversion methodology to Mauna Loa Solar Observatory CoMP and UCoMP observations. Using spectropolarimetric IQU measurements together with coronal seismology derived
magnetic field BPOS constraints, we recover vector
magnetic field solutions across the off-limb solar corona accessible to the observations, demonstrating the feasibility of routine large-scale coronal vector magnetometry without the need for Stokes V observations.
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All authors Alin Razvan Paraschiv, Zihao Yang, Daniela Adriana Lacatus, Momchil Molnar
Earth and Planetary Astrophysics · Cross-listed from physics.space-ph
Spectral Properties of Solar Wind Charge Exchange from Earth's Magnetospheric Boundaries: MHD and Test Particle Simulations
A. Ramachandran, R. T. Desai, H. L. Norman et al. (+6 more)
The Solar Wind Charge Exchange (SWCX) mechanism, where X-rays can be generated through interactions between heavy, highly charged solar wind ions and neutral atoms, offers an opportunity to observe the large-scale transfers of energy and momentum through the Sun-Earth system. In this study, we simulate SWCX signatures from Earth's outer boundaries using Gorgon global magnetohydrodynamic (MHD) simulations combined with kinetic particle-based simulations which we call the X-ray Imaging of the Magnetosphere (XIM) framework. The XIM-predicted emissivities agree with the predictions of the MHD model, producing enhanced emissions from the magnetosheath and cusp regions, but several differences are apparent. Compared with MHD, XIM shows enhanced structuring in the magnetosheath and notable enhanced emissions along the magnetopause associated with betatron acceleration. The results also evidence species-specific spatial variations, which are shown to vary compared to anticipated relative abundances in the solar wind and ion-specific properties. These simulations provide new insights into the underlying dynamics of SWCX at the Earth's outer boundaries, which can be used to understand what might be observed using X-ray observatories in space, such as the recently launched SMILE mission.
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All authors A. Ramachandran, R. T. Desai, H. L. Norman, Y. Tong, D. Bewicke, S. Nitti, J. A. Carter, J. P. Eastwood, J. P. Chittenden