Cosmology and Nongalactic Astrophysics
From Evidence to Evident: Decisive Cosmological Evidence for the Normal Neutrino Mass Hierarchy
Raul Jimenez, Carlos Peña Garay, Fergus Simpson et al. (+1 more)
Cosmological data have reached the precision needed to turn the
neutrino mass ordering from a weak
Bayesian preference into a decisive model-selection test. We compute the evidence for the Normal and Inverted Hierarchies by combining DESI DR2 clustering with NuFIT oscillation data. In baseline $\Lambda$CDM, DESI DR2 plus Planck CamSpec gives $\Sigma m_\nu<0.0642\,{\rm eV}$ at 95% confidence, close to the normal-ordering floor, $\Sigma m_\nu^{\rm NH}\simeq0.059\,{\rm eV}$, but well below the inverted-ordering minimum, $\Sigma m_\nu^{\rm IH}\simeq0.099\,{\rm eV}$. Thus the inverted hierarchy lies in the tail of the cosmological likelihood. The Bayes factor $K=P(D|{\rm NH})/P(D|{\rm IH})$ exceeds $460$ even for a conservative reference prior, and remains strong, $K>40$, in baseline-model extensions. We show that this result is robust to the choice between a reference prior and a physically motivated logarithmic hierarchical prior, marking the transition from prior-sensitive evidence to likelihood-dominated exclusion of the inverted hierarchy within standard cosmology.
Embedding these priors in the two-dimensional design space of measure (logarithmic versus linear in mass) and structure (hierarchical versus non-hierarchical), we find that all four prior constructions give decisive evidence under DESI DR2, with residual prior dependence governed mainly by the measure – a factor $\sim\!10$ in $K$ – rather than by the hierarchy assumption. At the prior-family level, the evidence favors the SJPV prior predictive over HS by a Bayes factor above $4,700$ across each matched-support variation tested. The favored normal ordering pushes the effective Majorana mass to the few-meV regime, with median $m_{\beta\beta}=3.28\,{\rm meV}$ and 95% credible interval $0.95<m_{\beta\beta}<11.55\,{\rm meV}$, below the inverted-ordering target for upcoming neutrinoless double-beta decay experiments.
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All authors Raul Jimenez, Carlos Peña Garay, Fergus Simpson, Licia Verde
Cosmology and Nongalactic Astrophysics
On the robustness of the angular homogeneity scale $\theta_H$: a comparative analysis of computational approaches
Pedro Fanha, António da Silva, José Fonseca et al. (+2 more)
The assumption of large-scale homogeneity is a cornerstone of modern cosmology and underlies the validity of the FLRW framework. Testing the scale at which the Universe transitions to homogeneity remains a key observational challenge, particularly with the increasing precision of
galaxy surveys. We aim to assess the robustness of the angular homogeneity scale, $\theta_H$, by systematically comparing different computational approaches used in its estimation and by quantifying the impact of methodological choices and physical clustering scales. We analyse mock
galaxy catalogues from the MICE Grand Challenge simulation. The angular fractal dimension $D_2(\theta_H)$ is computed using the Landy-Szalay
estimator and direct pair-counting methods. We implement different approaches, including symbolic regression, to model $D_2(\theta_H)$ and determine $\theta_H$. Uncertainties are estimated using resampling techniques and alternative parametric error propagation methods. We find that the estimation of $\theta_H$ is sensitive to methodological choices in the analysis, such as survey area,
redshift bin, numerical implementation and fitting strategy. While its
redshift evolution is robust, its absolute value is sensitive to both modelling choices and the presence of local clustering features. Our results highlight the importance of methodological systematics in homogeneity studies, showing that the determination of $\theta_H$ depends not only on the data, but also on the adopted analysis strategy. Flexible approaches such as symbolic regression provide a useful framework to model these effects, but also emphasize the need for careful modelling and survey design. This has important implications for future large-scale structure analyses aiming to test the Cosmological Principle with high precision.
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All authors Pedro Fanha, António da Silva, José Fonseca, José Pedro Mimoso, Ziad Sakr
Solar and Stellar Astrophysics
A Candidate Low-mass Disk-eclipsing Binary in the ~316 Myr Open Cluster UPK 13
Jiamao Lin, Yongkang Sun and Chengyuan Li
UPK~13-c2 is a candidate member of the $\sim$316~Myr open cluster UPK~13 and was previously classified as a white
dwarf + main-sequence (WD$+$MS) binary with 99.44% confidence. We present multi-band photometric evidence that it is instead more plausibly a late-K/early-M binary with a misaligned circumbinary disk. The photometry reveals a flat-bottomed eclipse at $P=36.71$~days with an approximately achromatic $\sim$40% flux decrement from the optical through $W1$, a reduced $W2$ depth, and a prominent mid-infrared excess at $W3/W4$. Two independent diagnostics strongly disfavor the WD$+$MS interpretation. First, the flat eclipse floor and 2.5-day ingress require complete occultation of an extended
stellar component; a white
dwarf would cross the disk edge in $\lesssim$2~hr and cannot naturally reproduce the observed multi-day trapezoid. Second, the difference spectrum is well fit by a single $\sim$4000~K thermal spectral energy distribution, favoring a late-K/early-M
dwarf over a white
dwarf as the occulted source. A decoupled SED decomposition yields a template-based late-K/early-M binary estimate of M1V+K9V with $M_{\rm tot}\approx1.4\,M_\odot$ and an overall systematic uncertainty of about 20%. Under a sharp-edge eclipse model, forward modeling of the light curve favors an eccentric, spatially localized occulting structure. The light-curve morphology places UPK~13-c2 in the same
geometric class as KH~15D and Bernhard-2. If cluster membership is confirmed, UPK~13-c2 may be the oldest known main-sequence disk-eclipsing binary.
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High Energy Astrophysical Phenomena
The flash-ionised SN Ibn 2025kzr: H-free CSM formed during a precursor outburst 55 days prior to explosion
S. de Wet, G. Leloudas, D. A. H. Buckley et al. (+33 more)
Type Ibn
supernovae (SNe) are a class of interacting SNe characterised by narrow helium lines in their spectra. We present an extensive observational
dataset of the Type Ibn SN 2025kzr at 51 Mpc, including the discovery of a precursor outburst with a peak brightness of M_r~-13.6 mag beginning ~55 days before explosion. Our photometry indicates the SN was discovered within the first day of explosion, showing fast-rising, ultraviolet-bright emission peaking at M_r=-19.26+/-0.09 mag and a peak blackbody temperature of T~29000 K, consistent with shock breakout within a region of dense and confined circumstellar material (CSM). Our high-cadence spectroscopic
dataset spanning 1.9-58.5 days post-explosion shows flash-ionised emission features during the first 10 days. In our SALT spectrum at 3.8 days we observe a pronounced blueshift of the He II lines by 460 km/s compared to the He I lines at zero velocity, while a Pickering-decrement analysis reveals a CSM that is fully hydrogen-free. The timing of the disappearance of the flash features combined with the CSM velocity of 1500 km/s imply a mass-loss event ~66 days before explosion, in close agreement with the timing of the precursor observed 55 days before explosion and strongly suggestive of a physical link. We derive a CSM mass of 0.03-1.7 M_sun and a corresponding high mass-loss rate >~10^{-1} M_sun/yr. The precursor timescale and energetics suggest an extreme mass-loss event that might be explained by wave-driven mass loss during the late stages of
nuclear burning, in particular the oxygen-burning phase. Overall, we favour a single massive Wolf-Rayet progenitor with M_ZAMS~30-40 M_sun to explain SN 2025kzr, although a binary origin cannot be excluded.
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All authors S. de Wet, G. Leloudas, D. A. H. Buckley, N. Erasmus, P. J. Groot, E. A. Zimmerman, P. Chen, Y. Tampo, M. Pursiainen, T. Killestein, F. Stoppa, G. K. Jaisawal, A. Gal-Yam, K. Maeda, J. Anderson, T.-W. Chen, M. Gromadzki, C. P. Gutiérrez, E. Kankare, T. E. Müller-Bravo, T. Pessi, S. Smartt, J. Sollerman, L. Tartaglia, D. R. Young, M. R. Alarcon, K. W. Smith, H. F. Stevance, T. de Boer, K. Chambers, C.-C. Lin, T. B. Lowe, P. Minguez, M. Nicholl, G. S. H. Paek, R. J. Wainscoat
Instrumentation and Methods for Astrophysics
WST Multi-Object Spectrograph Fiber Positioners:Development of a 32,000-Unit Precision Robotic System
Sébastien Pernecker, Maxime Rombach, Malak Galal et al. (+13 more)
The Wide-field Spectroscopic
Telescope Multi-Object Spectrograph requires an unprecedented fiber positioning system comprising 30'000 low-resolution and 2'000 high-resolution positioners across a 3.1 deg squared field of view. Each robotic positioner must achieve 5um RMS positioning accuracy in a densely packed focal plane, representing a more than sixfold scale increase over current instruments like 4MOST and DESI. To mitigate risks associated with industrial-scale production of 32'000 precision mechanisms, WST is pursuing a multi-concept development strategy. Four distinct positioner architectures are being prototyped and tested by an international collaboration (EPFL, AIP, UKATC, AAO) using 6.2 mm pitch triangular modules of 63 units each or a new inline modular concept. Performance metrics including positioning accuracy, repeatability, reconfiguration speed, collision avoidance, and manufacturability are being systematically evaluated. Down-selection to one or two concepts is planned for 2026-2027 during the HORIZON Europe-funded conceptual study phase. Current prototype testing demonstrates feasibility of meeting specifications, supporting WST's path toward first light in the early 2040s as ESO's next major spectroscopic facility.
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All authors Sébastien Pernecker, Maxime Rombach, Malak Galal, Jonathan Wei, Oliver Pineda Suárez, David Lee, Steve Watson, Younes Chahid, Chris Waring, Anmol Goyal, Joseph W. Barrow, Will Saunders, Jon Lawrence, Aaron Omadutt, Roelof S. de Jong, Jean-Paul Kneib
Solar and Stellar Astrophysics
The Quiet-Sun DEM Under Kappa: Diagnostic Degeneracy and the Failure of the Conductive Closure
Victor Edmonds
For a
plasma whose electrons carry a $\kappa \approx 2.5$ suprathermal tail, the Spitzer-Harm conductive closure does not exist: the conductive flux is the tail-carried third velocity moment, and the local conductivity integral diverges across the entire $\kappa \in [2,3]$ range – the finite value the closed-form $\kappa$-conductivity returns at $\kappa = 2.5$ is an analytic continuation of a divergent integral, not a physical conductivity. Edmonds (2026a) places the quiet
solar corona (QS) in this regime. Taking that as premise, two failures follow for any
plasma in the class: the standard EUV-DEM diagnostic cannot resolve such a
plasma, and the conductive term of the standard QS energy budget has no valid form. The diagnostic failure is shown end-to-end. A single-T $\kappa = 2.5$ probe, a multi-T $\kappa = 2.5$ source, and a multi-T Maxwellian source, all run through the regularized DEM inversion of Hannah & Kontar (2012), recover $\log T$ widths inside the FWHM distribution the same pipeline returns from 80 real quiet-Sun AIA patches; the pipeline cannot distinguish them. Two structural features also emerge: a Fe XI charge-state crossover and an EUV continuum reversal. The ionization-gated diagnostic structurally returns the tail-weighted effective temperature $T_{\mathrm{eff}}$, while Spitzer-Harm takes the bulk-core $T_{\mathrm{core}} = (\kappa - 3/2)/\kappa \cdot T_{\mathrm{eff}}$ as input. The mismatch invites a temperature substitution yielding a budget reduction – mechanically correct and physically empty, because the coefficient it corrects has no convergent form: it is the
Fourier-law closure itself that fails, not its temperature input. Two QS pillars for impulsive heating – DEM-width multi-thermality and the conductive-budget gap – lose their structural assumptions, and the budget question shifts to non-local kinetic transport outside any fluid closure.
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Earth and Planetary Astrophysics
TransitNet: A Compact Attention-Augmented Deep Learning Framework for Low-SNR Transit Blind Searches
Xingchen Yan, Jian Ge, Qingtian Liu et al. (+3 more)
Motivated by the observational incompleteness of intermediate-to-long-period Earth-size
planets, we present TransitNet, a compact
attention-augmented deep-learning framework for low-SNR transit blind searches. To enable realistic method development and objective threshold calibration under blind-search conditions, we develop a unified
dataset construction, benchmarking, and threshold-selection framework. On recovery
benchmarks constructed from unseen Kepler targets, TransitNet attains 95.2 percent accuracy in the challenging SNR range of 6 to 8 and outperforms both TLS and BLS, achieving ROC-AUC and PR-AP values of 0.974 and 0.982, respectively. In an injected Earth-size and sub-Earth-size transit recovery experiment, TransitNet achieves a recovery rate of 93.0 percent, substantially exceeding those of TLS (63.1 percent) and BLS (60.0 percent). In addition to detection, TransitNet provides
attention-based estimates of transit windows and midpoints. On an independent evaluation set, 97.4 percent of injected transits are fully covered by the estimated transit window. Applied to real Kepler observations, the model successfully recovers all 34 selected confirmed Kepler
planets, with a mean absolute transit midpoint error of 1.24 hours. The model combines a compact footprint of about 1.5 MB with high inference efficiency, yielding speed-ups of about 12 to 25 times relative to CPU-TLS and about 4 to 5 times relative to CPU-BLS. These results demonstrate that TransitNet provides an accurate, scalable, and computationally efficient framework for low-SNR transit blind searches in the tested regime and motivate its extension to longer-period Earth-size
planet searches.
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All authors Xingchen Yan, Jian Ge, Qingtian Liu, Kevin Willis, Quanquan Hu, Jiapeng Zhu
Instrumentation and Methods for Astrophysics
Advancing Control Electronics for Next-Generation Astronomical Fiber Robotic Positioners
Sebastien Pernecker, Jonathan Wei, Maxime Rombach et al. (+3 more)
Next-generation spectroscopic surveys require compact, high-density fiber robotic positioner systems achieving 5um precision, placing strict constraints on the size and the power budget of the control electronics. We present a compact control electronics architecture that drives 21 theta phi SCARA positioners (42 BLDC motors) on a single board, representing a significant increase in complexity compared to the electronics used in ongoing surveys such as SDSS V and DESI, where each positioner relies on dedicated hardware. The design integrates power distribution, CAN communication, and a synchronization line for simultaneous motion in high-density environments. Sensorless Field Oriented Control with collision detection and mechanical and
magnetic hard-stop calibration enables accurate positioning without
Hall sensors or encoders, reducing system cost and complexity. We describe the system architecture and performance validation, demonstrating that the module meets precision requirements while reducing the space required for control electronics and improving energy efficiency for future survey instruments.
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All authors Sebastien Pernecker, Jonathan Wei, Maxime Rombach, Oliver Pineda Suarez, Tarik Ibrahimovic, Jean-Paul Kneib
Instrumentation and Methods for Astrophysics
Testing of a 15-Positioner Module Based on the MPS Design for Stage-5 Telescopes
Jonathan Wei, Oliver Pineda Suárez, Malak Galal et al. (+6 more)
Assessing the performance metrics of theta-phi micro-robotic positioners is a key step toward understanding their operational behavior and ensuring that they meet the specifications of Stage-5 astronomical facilities, including the Chinese MUST, the American Spec-S5, and the European WST. A detailed examination of these metrics enables a clear evaluation of the system's current capabilities while also revealing aspects that require further refinement, which in turn guides improvements in design and manufacturing. In this work, carried out in collaboration with Micro Precision Systems (MPS) in Switzerland, we present the results of positioning performance and angular tilt characterization conducted on a 6.2-mm-pitch robotic positioner module developed for high-density fiber placement in next-generation spectroscopic instruments. The prototype unit evaluated in this study was produced by MPS. The measured metrics, including positioning repeatability, datum repeatability, backlash, non-linearity, and angular tilt, are compared directly with the nominal performance targets defined for Stage-5
telescope systems.
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All authors Jonathan Wei, Oliver Pineda Suárez, Malak Galal, Maxime Rombach, Sébastien Pernecker, Stefane Caseiro, Corentin Magnenat, Florian Boeckle, Jean-Paul Kneib
High Energy Astrophysical Phenomena
A thick-shell formalism for pulsar wind nebulae based on energy conservation
N. Bucciantini and B. Olmi
One of the most powerful approaches to model the structural and spectral
evolution of wind bubbles, and
pulsar wind nebulae in particular, is based on the one-zone thin-shell formalism. By solving a set of simple equations, one can relate the spectral properties of these systems to the physical properties of the
pulsar and
supernova remnant. Due to its predictive power, this approach has been widely used both to fit existing objects and in population synthesis. However, there are inconsistencies when applied to the Crab nebula that have never been fully accounted for, casting doubts on its reliability. We introduce a new and more flexible formalism based on energy conservation that reconciles the observed structural and spectral properties of the Crab nebula, solving the inconsistencies, and provides a more realistic description of wind-bubble
evolution. The equations of the formalism are presented and discussed, together with simplified solutions and more complex ones including radiation losses. Implications for the modeling of wind bubbles and
pulsar wind nebulae are illustrated. We also introduce a new high-order upwind-implicit scheme for particle-spectrum
evolution that ensures high accuracy in energy conservation, and an algebraic-vectorizable approach for synchrotron self-Compton emission in the full Klein-Nishina regime that avoids costly interpolations and integrations. We reproduce the Crab nebula structural properties and spectrum, accounting for the difference in convergence age between the optical filaments and the
radio bubble, thereby removing the inconsistencies. The spectral accuracy of this approach is comparable to that of the standard one, but it is superior in reproducing structural properties and accounting for geometrical effects such as a thick layer of mixed material and the lack of efficient coupling between the wind bubble and the surrounding medium.
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Instrumentation and Methods for Astrophysics
Performance Testing of a Trillium-based 21-Positioner Module for Stage-5 Telescopes
Oliver Pineda Suárez, Jonathan Wei, Malak Galal et al. (+4 more)
Evaluating the performance metrics of theta-phi robotic positioners is crucial to gather insights into the system's behavior and ensure their reliability during operation in Stage-5
telescopes such as the Chinese MUST, the American Spec-S5 and the European WST. With a careful analysis of these metrics, a comprehensive characterization of the system's strengths is obtained, alongside a clear identification of aspects requiring improvement. Thus, providing potential avenues for streamlining and optimizing its design and functionality. In this paper we present the results of the positioning performance and angular tilt tests conducted on 6.2-mm pitch robotic positioner modules developed for high-density fiber positioning in next-generation astronomical systems. The fiber positioners from the tested prototype adopt a mechanical design based on the Trillium open design from the Lawrence Berkeley National Laboratory (LBNL) and were produced by the Japanese company Orbray. The evaluated performance metrics of positioning repeatability, datum repeatability, backlash, non-linearity, and angular tilt were measured and compared to the desired performance for Stage-5
telescopes. The positioners exhibited a generally acceptable performance, although noticeable anomalies affecting several metrics were identified and will require mitigation in subsequent prototypes. Nevertheless, the results indicate promising performance suitable for Stage-5
telescope instrumentation, provided that these issues are successfully resolved.
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All authors Oliver Pineda Suárez, Jonathan Wei, Malak Galal, Melina Daniilidis, Maxime Rombach, Sébastien Pernecker, Jean-Paul Kneib
Cosmology and Nongalactic Astrophysics
Impact of lensing magnification on the power spectrum turnover
Yolanda Dube, Roy Maartens, Bikash R. Dinda et al. (+2 more)
The turnover scale $k_0$ of the matter power spectrum – and consequently of the standard
galaxy power spectrum monopole – encodes a fundamental signature of matter-radiation equality and constitutes an important standard ruler independent of
baryon acoustic oscillations. In principle, we can detect the turnover at multiple
redshifts and amplify the signal by stacking
redshift bins. However, in spectroscopic surveys reaching high
redshifts, such as the Euclid H$\alpha$ survey and the proposed MegaMapper Lyman-break
galaxy survey, the monopole of the observed
galaxy power spectrum receives a scale-dependent correction from
lensing magnification. This can modify the signal shape and shift the turnover scale, undermining its use as a standard ruler. Using mock surveys similar to Euclid and MegaMapper, we forecast this shift and the consequent bias in the turnover scale that is recovered from the mock data. The shift in the turnover scale grows with
redshift, leading to a maximum bias of $\sim 0.4\sigma$ (Euclid-like) and $\sim 3.6\sigma$ (MegaMapper-like). To avoid a bias $>1\sigma$, the maximum
redshift for a MegaMapper-like survey is $z\approx 2.9$. Data in the remaining range $2.9\lesssim z\le 5$ does not directly provide a reliable recovery of the intrinsic turnover. In fact, we find that the turnover vanishes in a MegaMapper-like survey for $z\gtrsim 3.7$. Our results show that the
lensing correction to the monopole should be included and carefully modelled when surveys are used to measure the cosmological turnover at high
redshifts.
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All authors Yolanda Dube, Roy Maartens, Bikash R. Dinda, Sêcloka L. Guedezounme, Sheean Jolicoeur
High Energy Astrophysical Phenomena
Pinning Down the Geometry of the Type Ic Broad-Line Supernova 2026gzf
Xudong Wen, Yi Yang, Jing Lu et al. (+11 more)
Type Ic broad-line
supernovae (SNe Ic-BL) are often associated with energetic explosions that display a
prompt outburst of high-energy emission. Since their progenitor lost the H and He envelopes before the explosion exposing the C/O core, their explosion dynamics and geometry can be seen in an unobscured and undistorted way. We present imaging polarimetry and spectropolarimetry of the Type Ic-BL SN 2026gzf obtained 4.6 and 16.5 days after the X-ray shock breakout, which was recorded by the Einstein Probe satellite as EP260321a, showing it to be one of the softest and intrinsically dimmest extragalactic fast X-ray transients. The persistent low continuum polarization indicates that the outer layer of SN 2026gzf is mostly spherical, suggesting the explosion did not significantly disrupt the progenitor envelope. At day 16.5, the calcium near-infrared triplet displays a peak polarization above 1.5%. The geometry of the associated line opacity is also compatible with an axisymmetric configuration. The spatial distribution of such oxygen-burning ashes thus indicates the presence of a
symmetry axis of the excitation structure within the nearly spherical ejecta. The Ca II triplet profile is dominated by a primary component spanning ~25,000–40,000 km/s, alongside a distinct secondary component extending above 28,000 km/s whose polarization implies a non-axisymmetric, complex excitation geometry toward the outer ejecta By implementing a three-dimensional Monte-Carlo calculation, we infer that a viewing angle of ~40 degree from the
symmetry axis of the excitation structure could plausibly reproduce the observed spectral and polarization profiles of the Ca II triplet.
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All authors Xudong Wen, Yi Yang, Jing Lu, Lifan Wang, J. Craig Wheeler, Miika Pursiainen, QiuJu Huang, Bao Wang, Xuefeng Wu, Alexei V. Filippenko, Wolfgang E. Kerzendorf, Giorgos Leloudas, Steve Schulze, Ferdinando Patat
Instrumentation and Methods for Astrophysics
Motorized Mount for the 3-DoF Folding Mirror 2 of the VLT's BlueMUSE Instrument
Gloria Mellinand, Diane Chapuis, Malak Galal et al. (+10 more)
BlueMUSE is a blue-optimized, medium spectral resolution, panoramic integral field spectrograph under development for the Very Large
Telescope (VLT). The project is now fully entering design phase. With an optimized transmission down to 350 nm, spectral resolution of R~3500 on average across the wavelength range, and a large FoV (1 arcmin2), BlueMUSE will open up a new range of
galactic and extragalactic science cases facilitated by its specific capabilities. To meet the stability demands required for BlueMUSE, motorized mounts for precise and repeatable positioning of key optics are developed. This paper explores candidate mechanical designs for BlueMUSE's Folding Mirror 2 (FM2), a high-precision mirror mount with three degrees-of-freedom: tip, tilt rotations, and vertical translation. The study includes a comparative performance analysis through theoretical simulations, details the mechanical, software and electronics architecture of the chosen design, as well as the dedicated optical setup design to characterize repeatability, precision, and thermal stability. The resulting performance of the chosen FM2 mount is then evaluated against the specified requirements for BlueMUSE.
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All authors Gloria Mellinand, Diane Chapuis, Malak Galal, Eirini Tagkoudi, Evan Touraine, Sébastion Pernecker, Rémi Giroud, Alexandre Jeanneau, Florence Laurent, Johan Richard, Chris Coote, Jon Moller, Jean-Paul Kneib
Instrumentation and Methods for Astrophysics
Design and Testing of the Motorized 2-DoF Folding Mirror 1 for the VLT BlueMUSE Instrument
Gloria Mellinand, Diane Chapuis Kerouanton, Malak Galal et al. (+9 more)
BlueMUSE is a blue-optimized, medium spectral resolution, panoramic integral field spectrograph under development for the Very Large
Telescope (VLT). The project is now fully entering the design phase. With an optimized transmission down to 350 nm, spectral resolution of R$\sim$3500 on average across the wavelength range, and a large FoV (1 arcmin), BlueMUSE will open up a new range of
galactic and extragalactic science cases facilitated by its specific capabilities. In this paper, we present the design, implementation and evaluation of the motorized mount developed for Folding Mirror 1 (FM1) of the VLT BlueMUSE instrument. The mount provides two degrees of freedom in tip and tilt and is engineered to correct misalignments caused by environmental variations. The preliminary results demonstrate that the motorized FM1 tilt mount achieves the required precision and maintains
alignment stability within the tight tolerances defined by the BlueMUSE project.
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All authors Gloria Mellinand, Diane Chapuis Kerouanton, Malak Galal, Axel Nicolier, Aurélien Genin, Zeno Amann, Sébastien Pernecker, Rémi Giroud, Alexandre Jeanneau, Florence Laurent, Johan Richard, Jean-Paul Kneib
Solar and Stellar Astrophysics
Revealing {\alpha}-Element's Past with Subaru/IRD: Oxygen Abundance of 35 Very Metal-Poor Stars from Near-IR OH lines
Bakuh Danang Setyo Budi, Wako Aoki, Nicholas Storm et al. (+10 more)
Oxygen abundances in very and extremely metal-poor (V/EMP)
stars provide critical constraints on early massive
stars' nucleosynthesis. An Oxygen abundance analysis is presented for 35 V/EMP
stars (-4.0<[Fe/H]< -1.5) using near-infrared H-band OH vibro-rotational lines from high-resolution Subaru/IRD spectra. To examine the reliability of these NIR OH lines, the results are compared with the abundances obtained from the 3D/NLTE-insensitive forbidden [OI] 6300Å line using archival high-resolution optical spectra. After homogeneously rederiving
stellar parameters and 1D/NLTE Fe abundances using
Gaia photo-astrometry and literature optical Fe equivalent width data, oxygen abundance from OH and [OI] lines is determined through 1D/LTE spectral synthesis. A sensitivity analysis confirms that near-IR OH lines are highly sensitive to the adopted temperature compared to the forbidden line. A temperature-dependent discrepancy between the tracers is identified: in cool red
giants (Teff <4600 K), OH-based abundances are systematically lower than [OI]-based abundance by 0.05 to 0.25 dex, while warmer red
giants show higher OH-based abundances as expected from 3D effects. Despite this systematic offset, the numerous measurable NIR OH lines yield significantly smaller random abundance errors than that of the single, weak [OI] line. Leveraging this statistical precision, an empirical calibration as a function of Teff, log g, [Fe/H], and [C/Fe] is derived to align the 1D/LTE OH abundances onto the [OI] scale. Applying this correction substantially reduces the scatter and temperature dependence in the [O/Fe] versus [Fe/H] plane and flattens the trend, bringing the results into fairly good agreement with
Galactic chemical
evolution models.
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All authors Bakuh Danang Setyo Budi, Wako Aoki, Nicholas Storm, Miho Ishigaki, Tadafumi Matsuno, Teruyuki Hirano, Masayuki Kuzuhara, Jun Nishikawa, Masashi Omiya, Takayuki Kotani, Tomoyuki Kudo, Sebastien Vievard, Motohide Tamura
Astrophysics of Galaxies
Disentangling the Distant Stellar Halo Using K-Giants in the DESI Year 3 Data
Namitha Kizhuprakkat, Andrew P. Cooper, Wenting Wang et al. (+42 more)
We present a sample of 88,959 K-
giants from DESI Milky Way Survey Year 3 data, which we use to characterize the chemo-dynamical properties of the
stellar halo at Galactocentric distances of 12 to ~100 kpc. Using HDBSCAN, we identify five prominent
stellar halo substructures: Aleph, the Sagittarius stream,
Gaia Sausage-Enceladus (GSE), Cetus-Palca and the Orphan-Chenab stream. We present the properties of each of these structures as they appear in our catalog, and examine how uncertainties on distance affect the characterization of substructure with this approach. We also examine regions associated with previously reported overdensities (such as the Virgo Overdensities and the Sagittarius spur) that we do not recover with HDBSCAN. The size and distance range of our catalog allows us to explore in detail the residual
stellar halo, comprising
stars that we do not associate with any substructure. We find that samples of ~2000 outer
halo stars with both highly prograde and highly retrograde angular momenta have similar
metallicity distribution functions (MDFs), which do not resemble the MDFs of either GSE or Sagittarius. Both the prograde and retrograde residual
halo MDFs are bimodal, with a metal-poor peak at [Fe/H] ~ -2 and a metal-rich peak at [Fe/H] ~ -1.3 (prograde) or -1.5 (retrograde). The MDF for lower angular momentum residual
halo K-
giants does not show clear evidence for a metal-poor peak, and broadly resembles the MDF of GSE, even at much lower binding energies than GSE itself. We discuss possible interpretations of these findings for GSE
accretion scenarios.
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All authors Namitha Kizhuprakkat, Andrew P. Cooper, Wenting Wang, Amanda Byström, Joan Najita, Sergey E. Koposov, Guillaume Thomas, Songting Li, Ruizhi Zhang, Carlos Allende Prieto, Mika Lambert, Oleg Y. Gnedin, Alexander H. Riley, Jessica N. Aguilar, Steven Ahlen, Davide Bianchi, David Brooks, Todd Claybaugh, Axel de la Macorra, Peter Doel, Enrique Gaztañaga, Satya Gontcho A Gontcho, Gaston Gutierrez, Dick Joyce, Robert Kehoe, Theodore Kisner, Anthony Kremin, Martin Landriau, Laurent Le Guillou, Marc Manera, Aaron M. Meisner, Ramon Miquel, Will Percival, Francisco Prada, Ignasi Pérez-Ràfols, Graziano Rossi, Eusebio Sanchez, David Schlegel, Michael Schubnell, Ray Sharples, Joseph H. Silber, David Sprayberry, Gregory Tarlé, Benjamin A. Weaver, Hu Zou
High Energy Astrophysical Phenomena
TransFit-MAG: Self-Consistent Modeling of Magnetar-Powered Transients from Shock Breakout to Spin-Down Heating
Jing-Yao Li, Liang-Duan Liu, Yun-Wei Yu et al. (+2 more)
Magnetar engines are widely invoked to power luminous optical transients, but their early emission depends on the coupled
evolution of engine injection, shock heating, adiabatic cooling, and radiative
diffusion. We present TransFit-MAG, a time-dependent radiative-
diffusion framework for magnetar-powered transients. The model couples the TransFit
diffusion solver to the dynamics of a magnetar-inflated
pulsar wind nebula (PWN) and its forward shock propagating through homologously expanding ejecta, calculating the internal radiation-energy distribution, photospheric
evolution, shock-heating location, and emergent luminosity self-consistently. For different parameter values, the model naturally produces well-separated double peaks, partially merged peaks, or single broad peaks. These results suggest that early bumps and broad single peaks in engine-powered transients may be understood within a unified engine–shock–
diffusion framework, in which the observed diversity reflects the coupled
evolution of central-engine power, shock propagation, and radiative transport through expanding ejecta. As an illustrative application, we fit the multiband optical light curves of the double-peaked SLSN-I LSQ14bdq.
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All authors Jing-Yao Li, Liang-Duan Liu, Yun-Wei Yu, Guang-Lei Wu, Yu-Hao Zhang
High Energy Astrophysical Phenomena
Discovery of a 24-millisecond pulsar in a very long orbit with the Murchison Widefield Array
Chia Min Tan, N. D. Ramesh Bhat, Bradley W. Meyers et al. (+9 more)
We report the discovery of PSR J0125$-$5854, a
pulsar with a
spin period of 24 ms and a dispersion measure of 11.66 pc cm$^-3$ in the ongoing Southern-sky MWA Rapid Two-metre (SMART) survey with the Murchison Widefield Array (MWA). The
pulsar is located at a high
Galactic latitude of $-57^{\circ}$, and at a distance of 0.5$\text{-}$1 kpc per the
Galactic electron density models. Follow-up observations with the MWA and MeerKAT
telescopes have revealed that this
pulsar is in a binary system with an orbital period of more than 290 days, and a steep spectrum (flux density, $ S \propto \nu^{\alpha} $, where $\nu$ is frequency and $ \alpha = -2.2 \pm 0.3 $). Analysis of current observational data hints at a potential binary configuration with an orbital period of $833.60 \pm 0.04$ days, a projected semi-major axis of $241.36 \pm 0.05$ light-seconds, and a minimum companion mass $0.4152 \pm 0.0001$ M$_\odot$, with a low eccentricity orbit of $0.0052 \pm 0.0006$. We discuss the potential formation channels for this system, and
conjecture that the companion is likely a Helium white
dwarf. Further observations are required in order to better constrain the orbital and
spin parameters. We discuss the implications of this discovery, which emerged after processing a small fraction of survey data, on the prospects of finding more millisecond
pulsars with the SMART survey, and with future surveys planned with the low-frequency SKA-Low.
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All authors Chia Min Tan, N. D. Ramesh Bhat, Bradley W. Meyers, Christopher P. Lee, Ewan D. Barr, Vivek Venkatraman Krishnan, Paulo C. C. Freire, Garvit Grover, Samuel J. McSweeney, Nicholas A. Swainston, Qiuyang Fu, Mengyao Xue
Instrumentation and Methods for Astrophysics
The atmospheric extinction curve at Lenghu site
Jin-Sheng Qiu, Xiao-Hui Xu, Qing-Feng Zhu et al. (+11 more)
In this study, we use a dedicated spectroscopic
telescope to carry out low-resolution measurements of the optical atmospheric extinction curve at Lenghu astronomical site in Qinghai Province, China. Observations of A0-type
stars are conducted over multiple nights between 2024 and 2026, covering airmasses from 1.0 to 2.0 and wavelengths in the range of 400 to 800 nm. We derive the extinction curve for the Lenghu site and compare it with those from Mauna Kea and Cerro Paranal.
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All authors Jin-Sheng Qiu, Xiao-Hui Xu, Qing-Feng Zhu, Xu Kong, Ting-Gui Wang, Lu-Lu Fan, Yong-Quan Xue, Ji-An Jiang, Zheng Lou, Xu Zhou, Xu-Zhi Li, Bo-Jun Tao, Jun-Han Zhao, Zhi-Yong Pu
Instrumentation and Methods for Astrophysics
The Array Control and Data Acquisition software of the Cherenkov Telescope Array Observatory
I. Oya, B. López, P. Aubert et al. (+61 more)
The Cherenkov
Telescope Array Observatory (CTAO) aims to advance knowledge of the gamma-ray sky as the largest gamma-ray observatory ever built. The CTAO will be deployed at two sites, one in the Northern Hemisphere and the other in the Southern Hemisphere, containing
telescopes of three sizes to cover different energy domains. Commissioning of the prototype CTAO Large-Sized
Telescope (LST-1) is being finalized at the northern site, while three additional LSTs are under construction. Additional calibration and environmental monitoring instruments, such as
laser imaging detection and ranging (
LIDAR) systems and weather stations, will support
telescope operations. The Array Control and Data Acquisition (ACADA) system serves as the central element for on-site CTAO operations. ACADA controls, supervises, and handles the data generated by the
telescopes and the auxiliary instruments. It drives the efficient planning and execution of observations while managing the multi-gigabit-per-second data streams produced by each CTAO
telescope. The ACADA system contains the CTAO Science Alert Generation Pipeline - a real-time data processing and analysis pipeline, dedicated to automatically generating science alert candidates as data are acquired. These science alerts, along with external alerts received from other scientific instruments, are managed by the Transients Handler (TH) component. The TH informs ACADA's Short-Term Scheduler (STS) about relevant science alerts, enabling modification of ongoing observations on sub-minute timescales. This capability for rapid response, combined with the fast slewing of CTAO
telescopes, makes the Observatory an excellent instrument for studying high-impact astronomical transients.
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All authors I. Oya, B. López, P. Aubert, G. Barni, P. Bauza, D. Berge, J.-P. Bolle, W. Boulakbech, P. Bruno, U. Bajc, A. Bulgarelli, M. Cappi, F. Cassol, S. Caroff, L. Castaldini, T. Collins, V. Conforti, A. Costa, L. David, G. De Cesare, E. de Ona Wilhelmi, A. Di Piano, K. Egberts, R. Fernandez, V. Fioretti, S. Fukami, E. García, E. Garcia, H. Gasparyan, S. Germani, J. Hinton, C. Hoischen, F. Incardona, D. Kostunin, E. Lyard, G. Maurin, D. Melkumyan, E. Mestre, K. Munari, T. Murach, A. Muraczewski, N. Nakhjiri, D. Neise, T. Oprinsen, G. Panebianco, N. Parmiggiani, E. Pietriga, V. Pollet, B. Rudak, I. Sadeh, S. Sah, A. Sarkar, M. Schefer, T. Schmidt, D. Soldevila, S. Spinello, C. Steppa, D.F. Torres, A. Tramacere, R. Vallés, T. Vuillaume, R. Walter, F. Werner, A. Wörheide
Solar and Stellar Astrophysics
Direct Optical Evidence of Late-Stage Infall in AB Aurigae: A Stagnant [O I] Reservoir and a Crushed Magnetosphere
Dipen Sahu, Rishikesh Sharma, Shubhendra Nath Das et al. (+2 more)
Massive
planet-carved cavities in transition disks should theoretically throttle inward gas transport, challenging our understanding of how central
stars maintain vigorous
accretion. To investigate how macro-scale late-stage infall traverses these gaps, we present multi-epoch, extreme-resolution (R ~ 107,000) PARAS-2 optical spectroscopy of the
benchmark Herbig Ae system AB Aurigae. By resolving the kinematics of H-alpha, He I 5876, [O I] 6300, 6363, and Na I D, we map the innermost
accretion environment. We find that the [O I] emission is centered near the
stellar rest velocity with symmetric broadening of ~ 35 km/s. Restricted to T <= 3800 K, this profile traces a stagnant, gravitationally bound Keplerian gas reservoir at ~ 1 au. Therefore, it provides strong optical evidence that late-stage infall accumulates in an inner gas reservoir and subsequently feeds the innermost
dust cavity. From this reservoir, gas is transported inward and crashes onto the
star, driving a highly active
accretion rate of dM/dt ~ 4 x 10^-7 M_sun/yr. The associated ram pressure crushes the
stellar magnetosphere to R_mag ~ 1.2 R_
star, which explains the restricted He I free-fall velocities and the highly variable inner wind. We also isolate a stable, slow H-alpha wind component, likely tracing an extended photoevaporative disk wind.
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All authors Dipen Sahu, Rishikesh Sharma, Shubhendra Nath Das, Abhijit Chakraborty, Justyn Campbell-White
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Implications of Adler-Finch-Skea solution on charged dark energy star satisfying Karmarkar Condition
Pramit Rej
A possible approach for preventing compact astrophysical objects from gravitational collapse into singularities is the idea of dark energy. Since it is the cause of our universe's accelerated expansion, it has the greatest impact on the cosmos. As a result, it appears that dark energy can interact with any compact astrophysical
stellar object [Phys. Rev. D 103, 084042 (2021)]. In this study, our primary objective is to develop a simpler model of a charged strange
star coupled with anisotropic dark energy admitting the Adler-Finch-Skea solution [J. Math. Phys. 15, 727 (1974); Class.
Quantum Grav. 6, 467 (1989)] within Einstein
gravity. To develop this model, the Karmarkar condition was employed to determine the radial metric component, while Adler's methodology was used to choose the time-metric component. For this purpose, we explored a particular strange
star, Her X-1, with observed values of mass $(0.85 \pm 0.15)M_{\odot}$ and radius $= 8.1_{-0.41}^{+0.41}$ km. In this context, we proceeded to model dark energy using the equation of state (EoS), such that the density of dark energy is proportional to the density of isotropic perfect fluid matter. The unknown constants in the metric were determined by smooth matching using the Darmois-Israel criterion. We conduct an in-depth examination of the stability and force
equilibrium of our suggested
star framework, as well as several physical characteristics of the model such as the metric function, pressure, density, mass-radius relation, and dark energy parameters. Thus, the physical consistency and stability of the present model are investigated. Therefore, following a comprehensive theoretical investigation, we discovered that our proposed model is singularity free and meets all the stability requirements to be a stable and physically realistic
stellar model.
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Earth and Planetary Astrophysics
Dust colour, phase behaviour, and Monte Carlo modelling of interstellar comet 3I/ATLAS from 4 au pre- to 4 au post-perihelion
F. Moreno, M. Serra-Ricart, J. Licandro et al. (+4 more)
We report multi-band photometric imaging observations and Monte Carlo
dust tail modelling of the interstellar comet 3I/ATLAS covering a wide range of heliocentric distances, from about 4 au pre-perihelion to 4 au post-perihelion. The extensive imaging data set allowed us to constrain the
dust physical properties, ejection speeds, and production rates as a function of heliocentric distance. The post-perihelion observations, obtained at high cadence in multiple photometric bands (SDSS g, r, i, and luminance filters) and spanning phase angles between approximately 0.7 deg and 30 deg, enabled us to determine the
dust color and phase function. The resulting phase curve exhibits a prominent backscattering enhancement, distinct from those derived for
Solar System comets, with an opposition surge of 0.1–0.4 mag, a width of 1–3 deg, and a linear phase coefficient of 0.02-0.04 mag/deg, consistent with independent pre-perihelion estimates. A possible interpretation of the imaging data, together with independent photometric measurements, indicates a
dust size distribution characterized by a power-law index of -3.5, with minimum and maximum particle radii of rmin = 10 micrometer and rmax in the interval 1-10 cm. The reported water production rate correlates well with the
dust production rate post-perihelion, but fails to do so pre-perihelion, an effect possibly linked to the high CO2/H2O ratio measured before perihelion. The derived maximum
dust-loss rate at perihelion is (0.5-1.8)E4 kg/s.
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All authors F. Moreno, M. Serra-Ricart, J. Licandro, P.J. Gutiérrez, L.M. Lara, I. Mariblanca-Escalona, M.R. Alarcón
Cosmology and Nongalactic Astrophysics
Exploring Primordial Non-Gaussianity Measurements in the CSST Spectroscopic Survey
Jiangnan Duan, Yan Gong, Qi Xiong et al. (+5 more)
Primordial non-Gaussianity (PNG) is a fundamental probe of the physics of the early Universe and inflation. Here we present a comprehensive study of the constraints on the local-type PNG parameter, $f_{\rm NL}$, for the spectroscopic
galaxy survey of the upcoming Chinese Space-station Survey
Telescope (CSST). Utilizing the high-resolution Jiutian N-body simulation suite, we construct realistic mock catalogs for emission line
galaxies (ELGs) at three representative
redshifts $z=0.3$, 0.6, and 0.9. The expected CSST observational characteristics are also considered, including
redshift uncertainties and selection functions based on signal-to-noise ratios of emission lines. We develop a robust analysis framework for the
redshift-space
galaxy power spectrum and bispectrum that accounts for
redshift-space distortions, scale-dependent bias, and nonlinear effects. Through a joint Markov Chain Monte Carlo (MCMC) analysis, we find that the power spectrum alone provides competitive constraints, while the inclusion of the bispectrum, specifically targeting the squeezed-limit configurations, improves the $f_{\rm NL}$ constraint precision by approximately 5%-6%. Our joint analysis yields a constraint result of $f_{\rm NL}=-20\pm52$ for the mock data in the 1~($h^{-1}$Gpc)$^3$ comoving volume at the three
redshifts, and the constraint accuracy is expected to be improved by several times or even one order of magnitude for the CSST full spectroscopic survey. This work demonstrates the potential of the Stage~IV surveys like CSST to probe inflationary physics, and highlights the importance of higher-order statistics in extracting information from large-scale structure surveys.
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All authors Jiangnan Duan, Yan Gong, Qi Xiong, Xuelei Chen, Qi Guo, Ming Li, Yun Liu, Wenxiang Pei
Cosmology and Nongalactic Astrophysics
Dynamical evolution of dark matter subhaloes in the Milky Way: role of the Galactic disc
Junnan Shen, Go Ogiya and Jens Stücker
Dark matter (DM) subhaloes orbiting inside the Milky Way (MW) are promising targets for DM searches, and reliable predictions for the detectability and spatial distribution of their signals are crucial for probing the nature of DM. Recent work showed that
tidal forces from the baryonic components of the MW boost the efficiency of subhalo mass-loss, although the underlying physical processes remain insufficiently understood. This study focuses on clarifying the role of the
Galactic disc. By using $N$-body simulations, we examine how the dynamical
evolution of subhaloes varies with the inclination angle between their orbits and the
Galactic disc. Subhaloes whose orbits are inclined by only a few degrees with respect to the
Galactic disc pass through it quickly, which enhances
tidal shock heating and leads to a pronounced increase in mass-loss efficiency. In contrast, when a subhalo orbit is exactly coplanar with the
Galactic disc, adiabatic shielding suppresses the energy input from
tidal shocks, resulting in a lower mass-loss efficiency.
Tidal stripping lowers the DM density within subhaloes, thereby attenuating the luminosity of their DM signals. Consequently, we expect that subhaloes located at distances of $\sim 0.3$–$2$\,kpc from the
Galactic disc plane emit only weak signals, whereas those remaining embedded in the disc are more promising candidates for indirect DM detection, provided that contamination from baryonic emission sources can be carefully modelled and subtracted. Although their mass-loss histories differ significantly, the structural
evolution of subhaloes is still well described by the
tidal tracks reported in the literature.
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Cosmology and Nongalactic Astrophysics
Onsite Calibration of the Shear-Shear Correlation
Cong Liu, Jun Zhang and Zhenjie Liu
Calibration of the
cosmic shear bias is crucial for justifying the cosmological results. However, it is still unclear to what extent calibrations based on simulated
galaxy images, as what is commonly done in the weak
lensing community, can capture the real shear bias, especially given the complicated instrumental effects. On the other hand, selections of the source
galaxies (magnitude cut,
redshift binning, etc.) made in real measurement, as well as
stochastic but possibly correlated shear biases, may introduce errors to the shear-shear correlations that are hard to calibrate apriori. In our previous few papers, we have shown that the field-distortion signal associated with each
galaxy image can be saved in the shear catalog to provide onsite calibrations of shear bias for both
galaxy-
galaxy lensing and shear-shear correlation. In this paper, we apply this method to the HSCpdr3 shear catalog generated by the
Fourier\_Quad shear measurement method. Using our onsite calibration method, we find that the shear biases vary with the selections of photo-z bins, SNR cuts, optical bands, as well as alternative forms of the shear
estimators. Nevertheless, after calibrations, the shear-shear correlation functions and cosmological parameter constraints show consistent results in all the cases considered. The fiducial results from the r/i/z bands shear catalog with $\mathrm{SNR}>10$ cut yield: $S_8=0.740^{+0.030}_{-0.030}$ and $\Omega_m=0.383^{+0.129}_{-0.132}$
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Transient Bias for CP Domain Wall Decay and Dark Matter
Sally Yuxuan Hao, Fangchao Liu, Shota Nakagawa et al. (+1 more)
Spontaneous CP violation (SCPV) provides an attractive solution to the strong CP problem. However, SCPV after inflation suffers from the formation of CP domain walls, requiring the maximal temperature of the Universe to lie below the CP-breaking scale. In the present work, we then propose a dynamical mechanism that removes this cosmological constraint without introducing permanent explicit CPV. We consider a new scalar field that acquires a large field value with a nontrivial phase in the early Universe and induces a transient bias among degenerate CP
vacua through a higher-dimensional interaction with a CP-breaking scalar field. This bias triggers the decay of CP domain walls after they form. As the new scalar field evolves toward the origin, the bias disappears, leaving the low-energy CP structure intact. We derive the conditions for successful domain wall decay and identify the viable parameter space. Furthermore, we point out that the coherent oscillation of the new scalar field naturally survives as dark matter, linking the resolution of the CP domain wall problem to the origin of dark matter.
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All authors Sally Yuxuan Hao, Fangchao Liu, Shota Nakagawa, Yuichiro Nakai
Earth and Planetary Astrophysics
ALMA 2D super-resolution imaging survey of Ophiuchus Class I/flat spectrum/II disks. II. Statistical analysis of stellar and disk properties
Ayumu Shoshi, Masayuki Yamaguchi, Takayuki Muto et al. (+5 more)
We present a statistical study of
stellar and
dust disk properties for young
stellar objects in the Ophiuchus
star-forming region. Building on our previous paper (Shoshi et al. 2025b), which applied two-dimensional super-resolution imaging with PRIISM to ALMA archival Band 6 continuum data and spatially resolved 78 disks, we analyze a sample of 67 systems with robust
dust-radius measurements. We combine
stellar parameters from the literature, including bolometric temperature $T_{\rm bol}$,
stellar mass $M_\ast$, and mass
accretion rate $\dot{M}_{\rm acc}$, with disk parameters derived from the super-resolution images, including inclination $i_{\rm disk}$, millimeter luminosity $L_{\rm mm}$, and
dust radius $R_{95\%}$. We quantify pairwise correlations and compare their behavior across evolutionary stages (Class I/FS and Class II) and between disks with and without detectable substructures. We identify substructure dependencies in $L_{\rm mm}$ and $R_{95\%}$, indicating that substructures tend to be found preferentially in relatively massive and extended disks. Moreover, we find a tight size-luminosity relation between $R_{95\%}$ and $L_{\rm mm}$. In particular, only Class II disks with substructures exhibit a steeper scaling, $R_{95\%}\propto L_{\rm mm}^{0.8}$, while the other subsamples are broadly consistent with $R_{95\%}\propto L_{\rm mm}^{0.4\text{-}0.5}$. This behavior is qualitatively consistent with disk
evolution models in which disks with
planet-induced pressure bumps follow a steeper size-luminosity relation than smooth disks. Overall, our results suggest that disk substructures play an important role in shaping the
evolution of
dust and global disk properties, while providing empirical constraints on
accretion,
dust trapping, and possible gravitational instability in young disks.
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All authors Ayumu Shoshi, Masayuki Yamaguchi, Takayuki Muto, Naomi Hirano, Ryohei Kawabe, Takashi Tsukagoshi, Shu Ishibashi, Masahiro N. Machida
Astrophysics of Galaxies
PMO Polaris CO survey. I. A 100 deg$^2$ view of the Polaris Flare
Xunchuan Liu, Bing-Gang Ju, Fujun Du et al. (+10 more)
Large-area CO surveys are essential for studying molecular cloud dynamics and
evolution; however, most have focused on the
Galactic plane, leaving high-latitude clouds less explored. We present the PMO Polaris CO Survey (PPCOS), which maps a 100~deg$^2$ region of the Polaris
Flare in the $J=1-0$ transitions of $^{12}$CO, $^{13}$CO, and C$^{18}$O using the Delingha 13.7~m
telescope. As the first large-area CO survey at high
Galactic latitude ($|b| > 20^{\circ}$) with sub-arcminute resolution, PPCOS achieves sensitivities of $\sim$0.46~K for $^{12}$CO and $\sim$0.23~K for $^{13}$CO and C$^{18}$O at a spectral resolution of 0.16~km~s$^{-1}$ and an angular resolution of 50\arcsec. The $^{12}$CO emission reveals seven distinct complexes, where only $\sim$10% of pixels display multiple velocity components, alongside a global velocity gradient of 0.18~km~s$^{-1}$~pc$^{-1}$. Typical line widths are $1.2 \pm 0.6$~\mbox{km~s$^{-1}$} for $^{12}$CO, while $^{13}$CO components are systematically narrower ($\lesssim 0.7\,\Delta V_{\rm ^{12}CO}$). The $^{12}$CO/$^{13}$CO intensity ratios (5–25) indicate widespread $^{12}$CO optical thickness, resembling conditions found in
giant molecular clouds (GMCs). Globally, the CO emission divides into two groups: a major group aligned with the velocity gradient and a secondary group elongated perpendicular to it, possibly regulated by large-scale coherent dynamics. We propose a three-layer hierarchy: a dynamically assembling and dispersing periphery traced by $^{12}$CO, a more stable intermediate kernel traced by $^{13}$CO, and gravitationally bound compact cores traced by C$^{18}$O. No young
stellar objects are firmly associated with the molecular gas. PPCOS provides an ideal laboratory for studying
turbulence, hierarchical structure, and early cloud
evolution in a nearby, relatively simple molecular cloud.
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All authors Xunchuan Liu, Bing-Gang Ju, Fujun Du, Tianwei Zhang, Lixia Yuan, Paul F. Goldsmith, Lianghao Lin, Zhihong He, Chao Zhang, Ping Yan, Shengyu Jin, Yongxing Zhang, Dengrong Lu