Solar and Stellar Astrophysics · Cross-listed from physics.plasm-ph
Anomalous Electric Fields in Earth's Turbulent Magnetosheath: Insights From 3D Hybrid Simulations
Jeffersson A. Agudelo Rueda, Julia E. Stawarz, Luca Franci et al. (+3 more)
In both collisional and collisionless
plasmas the presence of a broad range of electromagnetic and
plasma fluctuations provides anomalous electric fields that can be important for the dynamical
evolution of the system as it is the case of
magnetic reconnection,
plasma turbulence and dynamo theory. In the context of
plasma turbulence at scales larger than the ion's inertial length, the
plasma satisfies the frozen-in condition, and the anomalous electric fields are produced by correlations between turbulent velocity and
magnetic fields. Conversely, for collisionless
plasmas and at kinetic scales, the total electric field has additional contributions that arise from kinetic phenomena, namely, charge separation, ambipolar electric fields and electron inertia, and each of these terms presents an anomalous counterpart. In this work we characterize the anomalous electric fields. We present a framework that can explain partial balance between the anomalous resistivity and anomalous transport, and we use it to study anomalous electric fields at kinetic scales. We establish how the different contributions to the anomalous electric field couple to the large-scale electric fields and show that the anomalous terms act back-reacting on
magnetic-field organization and they may contribute to effective turbulent
magnetic diffusion or shielding. Finally, we test two Sub-Grid-Scale models including anisotropic transport coefficients and show that although these models partially recover the spectral information, the phase coherence is not entirely recovered by these models suggesting a more complex non-linear contribution of the anomalous terms to the resolved scales.
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All authors Jeffersson A. Agudelo Rueda, Julia E. Stawarz, Luca Franci, Nobumitsu Yokoi, Camille Granier, Silvio S. Cerri
Instrumentation and Methods for Astrophysics
The final design of GMagAO-X: the wavefront sensing and control (WFS&C) architecture of GMagAO-X
Sebastiaan Y. Haffert, Jared R. Males, Laird M. Close et al. (+10 more)
The Giant Magellan Adaptive Optics eXtreme (GMagAO-X) instrument has now been selected as an official part of the Giant Magellan
Telescope's (GMT) instrument suite. The instrument will be ready at first-light of the GMT in the mid 2030s. The instrument is now progressing towards its final design with a final design review planned for March, 2027. The high-density actuator deformable mirror with 21.000 actuators will allow GMagAO-X to create diffraction-limited images from visible to near-infrared. GMagAO-X will be coupled with high-performance coronagraphs to search for
exoplanets at the diffraction-limit. The coronagraphs require wavefront control at sub-nm precision. We will provide an update on the wavefront sensing and control architecture and how the loops interact with each other through end-to-end simulations.
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All authors Sebastiaan Y. Haffert, Jared R. Males, Laird M. Close, Olivier Guyon, Olivier Durney, Maggie Kautz, Liam Koning, Louis Desdoigts, Matthijs Mars, Elena Tonucci, Adam K. Taras, Yinzi Xin, Rico Landman
Astrophysics of Galaxies
Synchrotron filaments in radio galaxies: rarity, stability, and environmental influences from LOFAR and ROSAT observations
Geoffrey Ong'alo, Martin J. Hardcastle, Willice Obonyo et al. (+2 more)
We present a systematic investigation of filamentary synchrotron structures in
radio galaxies, using deep 144 MHz observations from the LOFAR Two-Metre Sky Survey (LoTSS) in combination with archival ROSAT X-ray data. These narrow, collimated features, linking
radio lobes and often aligned with jet axes, are rare: our visual inspection of 548 cluster-associated sources identified 12 candidates (~2.2%), of which three exhibit clearly resolved filaments suitable for detailed X-ray and synchrotron minimum pressure analysis. Minimum pressures in these filaments are consistently lower than the ambient thermal pressure derived from X-ray measurements. This disparity implies a role for external confinement in filament stability, aligning with theoretical predictions of thermal pressure support and potentially toroidal
magnetic field configurations. We discuss filament formation scenarios, including relic AGN outflows,
magnetic draping, and
plasma instabilities. Our findings highlight the utility of filamentary structures as probes of intracluster
magnetic field
topology and AGN feedback, and demonstrate the need for high-resolution, multi-frequency studies to constrain their origin and
evolution.
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All authors Geoffrey Ong'alo, Martin J. Hardcastle, Willice Obonyo, Marcus Brüggen, Paul Baki
Solar and Stellar Astrophysics · Cross-listed from nucl-th
Self-Consistent Determination of the Transition Temperature Between the $^{14}\mathrm{C}(n,\gamma)^{15}\mathrm{C}$ and $^{14}\mathrm{C}(p,\gamma)^{15}\mathrm{N}$ Reactions
R. Ya. Kezerashvili, N. A. Burkova, A. S. Tkachenko et al. (+1 more)
We present the first self-consistent theoretical study of the competing $^{14}\mathrm{C}(n,\gamma)^{15}\mathrm{C}$ and $^{14}\mathrm{C}(p,\gamma)^{15}\mathrm{N}$ reactions within the same modified potential cluster model (MPCM). For the $^{14}$C$(p,\gamma_{0})^{15}$N reaction, total cross sections, astrophysical $S$ factors, and reaction rates are calculated using interaction potentials constrained by the available scattering and bound-state data. The astrophysical $S$-factor is estimated as $S(0)=4.5(1)$~keV$\cdot \text{b}$. Combining these results with our recent MPCM calculations for $^{14}\mathrm{C}(n,\gamma)^{15}\mathrm{C}$, we determine the transition temperature at which
proton capture overtakes
neutron capture in the production of $^{15}\mathrm{N}$. The self-consistent comparison predicts a transition temperature $T_9^{\rm c.p.}=2.5$ under Maxwell–Boltzmann statistics, significantly higher than previous estimates. The analysis is extended to Tsallis statistics, demonstrating that deviations from thermal
equilibrium produce substantial shifts of the transition temperature. These results provide improved nuclear-physics input for astrophysical nucleosynthesis calculations.
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All authors R. Ya. Kezerashvili, N. A. Burkova, A. S. Tkachenko, S. B. Dubovichenko
Instrumentation and Methods for Astrophysics
Quantum-optimal instruments for high-contrast imaging with multi-plane light converters
Sebastiaan Y. Haffert, Yinzi Xin and Rico Landman
Spatial Mode Demultiplexers (SPADE) are devices that split an incoming wavefront into a particular set of electric field modes. SPADEs have been shown to be
quantum-optimal for many measurement problems including coronagraphy, wavefront sensing and interferometric (nulling) beam combiners. We will show how
quantum optimal SPADEs can be implemented using Multi Plane Light Converters (MPLC). MPLCs are devices that use several phase plates in sequence to achieve arbitrary
unitary transformations. The phase plates themselves are implemented using
liquid-
crystal technology that allows us to create high-quality broadband phase plates. The accurate control of the local phase through the direct write method results in MPLCs with minimal background scatter. We will show the designs and simulated performance for each of the proposed use cases for the ELTs, HWO and LIFE and show how they improve over current concepts.
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Earth and Planetary Astrophysics
The Hot Neptune Initiative (HONEI) III. An ultra-hot super Neptune orbiting the metal-rich subgiant star TOI-5646: the largest host for a desert dweller
L. Mancini, F. Manni, D. Kubyshkina et al. (+25 more)
We report the confirmation of the TESS transiting-
planet candidate orbiting the metal-rich F8\,IV-V subgiant
star TOI-5646 (V=11.38 mag; T=6136 K). The planetary nature of TOI-5646b was confirmed by means of HARPS-N follow-up radial velocity measurements. We determined that the
planet has an orbital period of 2.4277 days and an orbital eccentricity compatible with zero. With a mass of 45.9 Earth masses, a radius of 6.6 Earth radii, and an
equilibrium temperature of 1935 K, it is one of the hottest super-Neptune
exoplanets ever discovered in the Neptune desert. Its density, 0.87 g cm^-3, is lower than that of most other desert dwellers, but still appears to follow the trend that the desert is populated by dense
planets than those in the ridge and savanna. The
metallicity of the parent
star ([Fe/H]=0.32) follows the trend whereby the host
stars of Neptune-sized
exoplanets in the desert and the ridge are generally richer in metal than those in the savanna. The log{g} of the parent
star (4.09) suggests that the host is an evolved
star, making this a peculiar system: TOI-5646 is the largest
star (1.8 Solar radii) ever discovered to host a Neptune-sized
planet in the desert. Internal structure modelling revealed that TOI-5646b is highly enriched in metals, with an inferred bulk
metallicity between 0.7 and 0.95. Atmospheric
evolution simulations indicate that the
planet has undergone significant mass loss (6-16%) through intense XUV irradiation from its host
star. These results indicate a peculiar formation history (potentially involving early protoplanetary disk dispersal), a planetary collision, or a late tidal destruction event, to explain its current state as a low-density survivor in the Neptune desert.
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All authors L. Mancini, F. Manni, D. Kubyshkina, E. A. van Dijk, L. Naponiello, M. Damasso, V. D'Orazi, K. Biazzo, A. V. Bonomo, L. Fossati, Y. Miguel, J. de Leon, M. E. Everett, W. Fong, A. Fukui, D. Gandolfi, S. B. Howell, D. W. Latham, M. Lopez-Morales, P. MacQueen, F. Murgas, N. Narita, E. Palle, M. Pinamonti, T. Pugh, A. Sozzetti, S. Vissapragada, S. W. Yee
Cosmology and Nongalactic Astrophysics
A "MeerKAT-meets-LOFAR" Study of 2A 0335+096: Discovery of a Complex 500 kpc Radio Halo in a Disturbed Cool-Core Cluster
C. J. Riseley, R. J. van Weeren, L. Lovisari et al. (+9 more)
The emerging picture of
radio haloes and mini-
haloes in
galaxy clusters is more blurred and far less distinct than once thought. While both trace
cosmic ray electrons and
magnetic fields in the intracluster medium (ICM), our knowledge of the mechanisms powering these sources, their properties and their connection to cluster dynamics, is incomplete. We present new deep MeerKAT L-band (856$-$1712\,MHz) observations of the sloshing cool-core cluster 2A~0335+096, performed as part of the “MeerKAT-meets-LOFAR” mini-
halo census, as well as reprocessed LOFAR 120$-$168\,MHz LOFAR Two-metre Sky Survey data. We present highly sensitive
radio continuum images, from which we perform a spectral analysis and a comparison of the thermal and non-thermal properties using reprocessed archival XMM-Newton data. Our MeerKAT data reveal that the known mini-
halo is embedded in a large-scale
radio halo spanning up to 510\,kpc in this sloshing cluster, although only the inner mini-
halo is detected by LOFAR. We find a typical steep spectrum of $\alpha = -1.20 \pm 0.09$ for the mini-
halo; the non-detection of the larger-scale
halo by LOFAR indicates a spectral index no steeper than $-1.2$. Our results are broadly consistent with an interpretation of turbulent (re-)acceleration powered by sloshing within the cluster potential well. This work emphasises the need for using deep, high-dynamic multi-frequency
radio observations in conjunction with high-quality X-ray observations to complete our understanding of the connection between
radio halo properties and cluster dynamics.
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All authors C. J. Riseley, R. J. van Weeren, L. Lovisari, R. Timmerman, A. Botteon, A. Bonafede, A. Ignesti, N. Biava, G. Brunetti, B. Colquhoun, Y. Perrott, T. Vernstrom
Instrumentation and Methods for Astrophysics
The Photonic Lantern Nuller: from concept to laboratory and on-sky demonstrations
Yinzi Xin, Nemanja Jovanovic, Dimitri Mawet et al. (+18 more)
This thesis work presents the conceptual design and experimental characterization of the Photonic Lantern Nuller instrument, which uses a multimode-to-single-mode demultiplexing waveguide to cancel out starlight while maintaining
planet light, allowing for the direct characterization of
planets at a
telescope's diffraction limit. The PLN was experimentally characterized in the lab, where it was further enhanced using common-path wavefront sensing and control techniques, and then demonstrated on sky at the Subaru
Telescope. Highlights include measured in-lab null-depths of $\sim 10^{-4}$ in three out of four ports simultaneously and on-sky null-depths of approximately $\sim 10^{-1}$ (limited by jitter and atmospheric residuals). We provide an overview of these results and discuss avenues for future work.
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All authors Yinzi Xin, Nemanja Jovanovic, Dimitri Mawet, Daniel Echeverri, Yoo Jung Kim, Jonathan Lin, Julien Lozi, Sebastien Vievard, Olivier Guyon, Grace Piroscia, Vincent Deo, Sergio Leon-Saval, Rodrigo Amezcua-Correa, Stephanos Yerolatsitis, Sebastiaan Y. Haffert, Michael P. Fitzgerald, Pradip Gatkine, Suvinay Goyal, Barnaby Norris, Garreth Ruane, Steph Sallum
High Energy Astrophysical Phenomena
The First X-Ray Polarimetry of the Typical Accretion Disk Corona Source 4U 1822-37
WanYun Wu, Fei Xie and YuShan Ling
We report the first Imaging X-ray Polarimetry Explorer (IXPE) observations of the typical
accretion disk corona (ADC) source 4U 1822-37, covering 44 orbital cycles, together with simultaneous Swift-XRT data. The polarization degree (PD) of this source is found to be higher than typical low-mass X-ray binary (LMXB) values and exhibits a significant energy dependence. Within the 2–5~keV and 5–8~keV bands, PD remains constant, with average values of \(5.6\pm0.8\%\) and \(11.6\pm1.7\%\), respectively, and the difference is significant (\(>3\sigma\)). Orbital phase-resolved analysis reveals that during the companion eclipse, the PD in the 2–5~keV band drops from a significantly non-zero value to a level consistent with zero, while the polarization angle (PA) remains unchanged. In contrast, the PD in the 5–8~keV band shows a marginal rising trend, reaching \(21.3\pm6.1\%\), and the PA exhibits a periodic rotation of \(30^\circ\) before the eclipse. In addition, the PA rotates by \(40^\circ\) with increasing neutral absorption on a three-day timescale. These results suggest that the soft and hard emission in the 2–8~keV band may originate from regions with different spatial distributions, with the high PD implying a scattering contribution. The PA rotation is likely linked to scattering geometry asymmetries caused by a bulge or clumps.
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Instrumentation and Methods for Astrophysics
Demonstration of simultaneous PIAA- coronagraphy and wavefront sensing using a single metasurface-based focal-plane optic
Dhwanil Patel, Sebastiaan Y. Haffert, Skyler Palatnick et al. (+23 more)
Controlling residual wavefront aberrations downstream of an extreme adaptive optics (ExAO) system is a major challenge in high-contrast imaging. These aberrations produce quasi-static speckles due to differences between the wavefront-sensing and science paths. Highly sensitive wavefront sensors, such as Zernike wavefront sensors (ZWFSs), are used to mitigate these non-common path aberrations. High-performing coronagraphs, such as complex mask coronagraphs (CMCs), are also implemented in the focal plane. Both perform better with lossless apodization such as phase-induced amplitude apodization (PIAA) optics. Metasurfaces can have chromatic responses, allowing a single focal-plane optic to have different functionalities in different wavelength bands. We demonstrate such an optic by manufacturing a hybrid metasurface designed to function as a CMC and a ZWFS in two intermediate-band filters in the H band, each with a fractional bandwidth of approximately 1%. We show measured optical responses with phases of $\sim \pi/2$ at shorter wavelengths and $\pi$ at longer wavelengths between $1500$ and $1700,\text{nm}$. This would allow for wavefront sensing at the shorter wavelength of $\sim1500\,\text{nm}$ and coronagraphy at the longer wavelength of $\sim1700\,\text{nm}$. Additionally, we tested the mask on-sky with the MagAO-X instrument at the Magellan Clay 6.5 m
telescope at Las Campanas Observatory, Chile. On-sky results show a contrast of $\sim 10^{-1}$ at a non-ideal wavelength of $\sim 1600\,\text{nm}$. This is comparable to simulated contrast curves using the measured optical responses around that wavelength. Finally, we evaluated the wavefront-sensing performance of the metasurface using the MagAO-X internal source at $1300\,\mathrm{nm}$. The measured reconstruction error is consistent with simulations of an ideal Zernike wavefront sensor, confirming its wavefront-sensing functionality.
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All authors Dhwanil Patel, Sebastiaan Y. Haffert, Skyler Palatnick, Adam Taras, Maxwell A. Millar-Blanchaer, Matthijs Mars, Elena Tonucci, Jared R. Males, Laird M. Close, Joshua Liberman, Warren B. Foster, Kyle Van Gorkom, Olivier Guyon, Alexander D. Hedglen, Parker T. Johnson, Maggie Y. Kautz, Jay K. Kueny, Jialin Li, Joseph D. Long, Jennifer Lumbres, Eden A. McEwen, Avalon McLeod, Lauren Schatz, Katie Twitchell, Robert J. Harris, Viktoria Kutnohorsky
Cosmology and Nongalactic Astrophysics
The Effect of Slitless Spectroscopic Redshift Uncertainty and Interlopers on BAO Measurements from CSST-like Samples
Zhejie Ding, Yu Yu and Pengjie Zhang
The baryon acoustic oscillations (BAO) is a vital probe to measure cosmological distances and constrain dark energy. The ongoing and near-future space-based
telescopes, including the Chinese Space Station Survey
Telescope (CSST), will perform
galaxy redshift surveys using slitless spectroscopy. Due to the relatively low spectral resolution and observational effects, there will be uncertainties and interloper contamination in measured
redshifts. In this study, we consider the Gaussian-distributed
redshift uncertainty and [O III]-H$\beta$ interlopers in the CSST-like slitless spectroscopic
redshift (spec-z) samples, which are simulated using the approximate $N$-body code FastPM. We study the effect of spec-z errors on BAO before and after density field reconstruction. Both the
redshift uncertainty and interlopers can damp the BAO signal, and the latter can further induce oscillations in the broadband shape of the power spectrum. We model the interloper effect on the propagator, i.e. the cross-correlation between the observed and initial density fields, as well as on the BAO power spectrum. We study the influence of the spec-z errors on the fitted anisotropic BAO parameters $\alpha_{\perp}$ and $\alpha_{\parallel}$. The resulting systematic bias on $\alpha_{\perp}$ and $\alpha_{\parallel}$ is mild, mostly within $0.1$ per cent and $0.2$ per cent, respectively. Even with the spec-z errors, BAO reconstruction can still significantly reduce the systematic bias and statistical errors on the $\alpha$ parameters. Furthermore, we vary the
redshift uncertainty and study the reconstruction performance.
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Earth and Planetary Astrophysics
Nitrogen- and nitrogen-oxygen-bearing organic molecules in comet 67P/Churyumov-Gerasimenko: An untargeted investigation
N. Hänni, K. Altwegg, D. Baklouti et al. (+6 more)
Comets provide a unique window into the history of the Solar System as they carry some of the best-preserved material and make it available to in situ exploration. A milestone in comet studies was the European Space Agency's Rosetta mission, which, for the first time, rendezvoused with a comet, namely 67P/Churyumov-Gerasimenko (67P), and studied it from a close range for two years. Amongst other unexpected insights, data from this mission show that comets contain a surprisingly large portion of organics, both in the refractory and the icy phases. For this work, we evaluated high-resolution mass spectra collected in comet 67P's inner coma by Rosetta's ROSINA-Double Focusing Mass Spectrometer (DFMS). In unprecedented detail, we investigated the N- and NO-bearing cometary complex organic molecules (COMs) of the general sum formula CnHmN and CnHmNO, where n and m are the stoichiometric coefficients of carbon and hydrogen. Our discussion-driven approach combines the empirical concept of Occam's razor with knowledge from studies of relevant astrophysical environments and constraints expected from naive bottom-up assembly of molecules. We present an exemplary minimal and non-unique set of molecules needed to explain the DFMS observations. While this set might not capture the full organic diversity, but rather its lower limit, it identifies many N- and NO-bearing COMs with reasonable certainty, while excluding others, potentially informing future observational campaigns, and hence contributes to the exploration of the origin and
evolution of organic complexity in space. Among the key results is strong evidence for an abundant presence of heterocycles as well as substantial alkylation of both cyclic and acyclic species. These findings align well with reports on soluble organic matter in meteorites and asteroids and ...
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All authors N. Hänni, K. Altwegg, D. Baklouti, M. Combi, S. A. Fuselier, J. De Keyser, D. R. Müller, M. Rubin, S. F. Wampfler
Astrophysics of Galaxies
An HI study of a large sample of ultra-diffuse galaxies
Ruilei Zhou, Ming Zhu, Chuan-Peng Zhang et al. (+5 more)
By cross-matching the SMUDGes catalog with the FASHI and ALFALFA HI surveys, we construct an HI-detected sample of 112 ultra-diffuse
galaxies (UDGs) and 48 low-surface-brightness (LSB)
galaxies, providing HI-based
redshifts for 76
galaxies for the first time. Using DESI DR1
redshifts, we assemble an HI-non-detected sample of 168
galaxies for stacking analysis, with detections in two stellar mass bins below 10^{8.5} M_sun. Combining optical, UV, and HI data, we investigate stellar masses,
star formation rates, gas fractions, and kinematics. We present a systematic analysis of the HI mass–optical size relation for UDGs and LSBs, showing both populations follow a mass–optical size scaling similar to normal
galaxies, suggesting an average HI surface density, under the assumption that the optical size traces the extent of the HI distribution. Their stellar mass–size relation indicates nearly constant stellar surface densities for
galaxies with central surface brightness mu_{0,g}>~24mag arcsec^{-2}, independent of UDG or LSB classification. Many UDGs and LSB
galaxies are systematically offset from the baryonic Tully–Fisher relation toward higher baryonic masses at a given velocity, consistent with trends found in UDGs with resolved HI kinematics. Both populations exhibit low
star formation efficiencies and long gas depletion times, supporting multiple formation pathways for UDGs.
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All authors Ruilei Zhou, Ming Zhu, Chuan-Peng Zhang, Lin Du, Cheng Cheng, Qi Guo, Tian-Wen Cao, Wenzhe Xi
Astrophysics of Galaxies
SDSS-IV MaNGA: Star Formation Cessation in Low-redshift Galaxies. III. Dependence on Quenching Criteria
Zhuo Cheng, Tao Jing, Cheng Li et al. (+1 more)
This paper is the third in a series of studies investigating
star formation cessation in nearby
galaxies on kiloparsec scales. Using the final SDSS-IV MaNGA data release, we ask how the inferred importance of global, local, and environmental properties depends on the operational definition of quenched regions. We classify spaxels as
star-forming, reliably quenched, or potentially quenched by accounting for measurement uncertainties, and train random forest classifiers with a parameter set chosen for direct comparison with previous work. For reliably quenched regions, the local stellar mass surface density $\Sigma_\ast$ consistently has the highest feature importance, independent of quenching definition. By contrast, the high importance of central velocity dispersion $\sigma_c$, previously interpreted as evidence for
galaxy-wide AGN feedback, is recovered mainly when potentially quenched regions are included. The leading parameter also varies with stellar mass: $\Sigma_{\rm 1kpc}$ is most important below $\sim10^{10.2}\,\textrm{M}_{\odot}$, whereas local quantities such as $\Sigma_\ast$ and $\sigma_\ast$ become more prominent at high masses. These results show that quenching criteria and uncertainty treatment can reconcile apparently discrepant feature-importance studies. AGN-related processes may contribute to ambiguous regions, but the reliably quenched population is most tightly linked to high local stellar density.
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All authors Zhuo Cheng, Tao Jing, Cheng Li, Renbin Yan
Solar and Stellar Astrophysics
Flare waiting time as a novel proxy of stellar magnetic activity
Henggeng Han, Song Wang, Chuanjie Zheng et al. (+3 more)
Stellar
flares have long served as stellar
magnetic activity tracers. The
flare waiting time, defined as the interval between two consecutive
flares, provides a valuable diagnostic for probing underlying mechanisms of energy storage and release in stellar atmospheres. In this work, utilizing flaring M dwarfs observed by the Kepler satellite, we establish a simple yet effective activity proxy, i.e., median
flare waiting time ($t_{\rm{w, med}}$). Our results show that the $t_{\rm{w, med}}$ can trace long-term activity levels similar to the
flare rate. However, $t_{\rm{w, med}}$ corresponding to different waiting time percentiles may encode richer physical insights than
flare rate. In addition, for the first time we construct a clear relation between $t_{\rm{w, med}}$ and stellar rotation period, which is quite similar to the canonical activity–rotation relation. More intriguingly, this relation exhibits a more notable supersaturation effect (i.e., below a critical rotation period, $t_{\rm{w, med}}$ begins to increase instead of keeping constant) compared to other activity proxies. The filling factor–rotation period relation favors poleward migration of active regions as the explanation for supersaturation, rather than coronal stripping. With the dramatic increase in stellar
flares detected by missions like TESS and the upcoming Earth 2.0 satellite, $t_{\rm{w, med}}$ will become a powerful diagnostic for probing stellar
magnetic activity and underlying physics.
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All authors Henggeng Han, Song Wang, Chuanjie Zheng, Cunshi Wang, Xue Li, Jifeng Liu
High Energy Astrophysical Phenomena
Molecular and Atomic Gas Associated with the Gamma Ray Supernova Remnant RCW 103
H. Inoue, Y. Asano, R. G. Bhuvana et al. (+15 more)
We present a study of the interstellar molecular and atomic gas associated with the gamma-ray
supernova remnant (SNR) RCW 103 using the Mopra $^{12}$CO($J$ = 1-0), Atacama Large Millimeter/submillimeter Array $^{13}$CO($J$ = 1-0), and the Australia
Telescope Compact Array & Parkes HI data. We find that CO clouds in the velocity range from $-58.7$ to $-43.5$ km s$^{-1}$ show a clear spatial correspondence with the X-ray shell of RCW 103, particularly extending from the northwestern to the southeastern regions. The position-velocity diagram of the CO emission reveals an expanding gas motion with an expansion velocity of $\Delta V \sim$$7.5$ km s$^{-1}$, which may have been produced by shock waves and/or stellar winds from the progenitor system. We estimate the total
cosmic-ray
proton energy to be $\sim$$3.0^{+1.1}_{-0.6} \times 10^{47}$ erg, adopting a total interstellar
proton density of $\sim$$810$ cm$^{-3}$. This value is more than an order of magnitude lower than those inferred for other gamma-ray emitting SNRs of comparable age. Given that a substantial amount of dense gas remains within the interior of RCW 103, where thermal X-ray emission is dominant, our results possibly suggest that a significant fraction of the shock energy may have been converted into thermal energy via gas heating, thereby reducing the efficiency of
cosmic-ray acceleration.
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All authors H. Inoue, Y. Asano, R. G. Bhuvana, R. Z. Alsaberi, R. Yamada, K. Tsuge, T. Murase, Y. Fukui, E. M. Reynoso, K. Tachihara, N. Izumi, M. Yamagishi, K. Furuya, N. Harada, K. Tokuda, G. Rowell, M. D. Filipović, H. Sano
High Energy Astrophysical Phenomena
X-ray Polarization of Inverse Compton Scattering by Thermal and Nonthermal Electrons
Boting Wang, Jirong Mao, Jieying Liu et al. (+1 more)
X-ray emission from
accretion-powered astrophysical systems is widely interpreted as inverse Compton (IC) scattering between energetic electrons and soft
photons. Besides the emitted intensity, the polarization of this radiation provides important information about the physical properties of the electrons involved. We investigate how different electron populations shape both the spectrum and polarization of IC emission in the X-ray band. We consider three electron populations: purely thermal, purely nonthermal power-law, and a hybrid population combining both components. We take both numerical simulations and semi-analytic calculations. We first attempt the cases for thermal and nonthermal electrons, respectively. We then focus on the hybrid population, which is expected to be realistic in high-energy object environments. For the case of hybrid electrons, the scattered emission separates into three energy regimes. At low energies ($\lesssim 0.1$ keV), it is dominated by thermal electrons; at high energies ($\gtrsim 4$ keV), it is governed by the nonthermal component. Between these limits, a transition band ($\sim 0.1$-$4$ keV) appears in which both components contribute. The degree of polarization varies smoothly across these regimes, and the behavior in the transition band directly traces the relative importance of thermal and nonthermal electrons. We further show that for partially polarized seed
photons, the scattered polarization scales linearly with the incident polarization while its frequency dependence remains unchanged. These results show that X-ray polarimetry provides a powerful diagnostic of the electron energy distribution in
accretion-powered systems.
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All authors Boting Wang, Jirong Mao, Jieying Liu, Fei Xie
High Energy Astrophysical Phenomena
Observations of ionized carbon towards the $\gamma$-ray-bright supernova remnant RX J1713.7-3946
A.R. Thakur, G.P. Rowell, R. Higgins et al. (+7 more)
The origin of Galactic
Cosmic Rays (CRs), particularly at sub-GeV energies, remains uncertain due to their difficulty in being traced. One possible tracer of low-energy CRs is ionised carbon ([C II]), which may be enhanced in regions affected by CR-induced ionisation. We present observations of [C II] 158 $\mu$m line emission across the $\gamma$-ray-bright
supernova remnant (SNR) RX J1713.7-3946 obtained with SOFIA. These data are compared with molecular and atomic gas from Mopra ($^{12}$CO), Nanten ($^{12}$CO) and SGPS (HI), and high-energy emission from TeV $\gamma$-ray H.E.S.S. and X-ray XMM-Newton. We find [C II] emission follows the atomic gas more closely than molecular gas, particularly in regions near the SNR shock front. Ratios of [C II] intensity to gas column density vary across the remnant, with peak values coinciding with regions of enhanced TeV $\gamma$-ray emission. To put the [C II] in a wider context, we examined pointings from the Herschel GOT C+ survey. Our analysis of the GOT C+ data shows no significant difference in the I[C II]/I[$^{12}$CO] ratio for observations towards
star formation regions, HII regions and SNRs. To assess the origin of carbon ionisation, we model [C II] emissivity using the photoionisation code CLOUDY. We find UV
photons and CRs can produce comparable levels of [C II] emission, assuming low-energy CRs (< 1 GeV) are accelerated and trapped within the SNR shock. These results highlight the potential of [C II] as a tracer of CR ionisation and the importance of combining multi-wavelength observations to probe CR interactions in SNRs.
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All authors A.R. Thakur, G.P. Rowell, R. Higgins, M. Burton, Y. Fukui, S. Einecke, H. Sano, G. Wong, M.D. Filipović, C. Braiding
High Energy Astrophysical Phenomena
The impact of circumstellar wind-blown bubbles on the dynamics of pulsar wind nebulae and supernova remnants
Lioni-Moana Bourguinat and Pierrick Martin
The core-collapse
supernova explosion of most massive
stars is followed by the development of a
supernova remnant (SNR) and
pulsar wind nebula (PWN) system whose
evolution is in part dictated by its surrounding environment. The latter is frequently assumed to be the typical interstellar medium (ISM). However, massive
stars emit powerful winds during their lifetime and carve extended circumstellar cavities known as wind-blown bubbles (WBBs). We investigated the impact of WBBs on the dynamics, energetics, and thermal X-ray emission of a SNR-PWN system. We performed numerical simulations of a 1D hydrodynamical analogue of the system, for different stellar progenitors and
pulsar parameters, in a WBB or ISM environment. The system initially expands to large sizes in the low-density interior of a WBB, until the SNR fills the entire bubble. The PWN grows to $\gtrsim10~\mathrm{pc}$ ($30~\mathrm{pc}$) after $\sim5~\mathrm{kyr}$ ($\sim25~\mathrm{kyr}$) for a $M=8~\mathrm{M}_\odot$ ($M=20~\mathrm{M}_\odot$) progenitor, $5-6$ times larger than in an ISM environment. The impact of the SNR on the massive outer shell of the WBB generates a strong reflected shock that efficiently returns energy to the inner parts of the system. At late times, after a strong compression of the PWN by an order of magnitude in size, back-and-forth shock crossings of the cavity maintain the SNR at very high temperatures and drive a vigorous reverberation of the PWN, with changes in radius by up to $3-4$. In this stage, the PWN is on average $2-4$ times larger than in an ISM environment and contains up to an order of magnitude more energy. Thermal radiation from the system occurs in few very localised emission bursts, as low-velocity shocks are transmitted across the bubble shell when it is hit by blast waves. WBBs offer a possible explanation for the large sizes of many PWNe and the non-detection of their parent SNRs.
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Astrophysics of Galaxies
Decoupling candidate dual AGN from chance superpositions in the GOTHIC survey via a deep-learning framework
Bhavesh Mukheja, Snehanshu Saha, Anwesh Bhattacharya et al. (+3 more)
Dual active galactic
nuclei (DAGN) mark a critical phase in the
evolution of merging
galaxies and the pairing of supermassive black holes, yet they remain difficult to identify in large imaging surveys because of projection effects and limited spatial resolution. Compact foreground
stars and unresolved substructure can mimic dual
nuclei through chance superposition, complicating automated detection. We revisit the 46,061
galaxies flagged but rejected as DAGN candidates by the GOTHIC pipeline, primarily because the two
nuclei fell within the SDSS fibre aperture or exceeded its separation threshold. We train a supervised deep-learning framework based on the YOLOv11 oriented-bounding-box architecture on annotated SDSS imaging to separate genuine dual
nuclei from foreground stellar contaminants and other spurious
alignments. The final model attains a validation precision of 0.919, recall of 0.905, and $F_1$ of 0.912 for the dual-
nuclei class, and yields 29,605 dual-
nucleus candidates after removing
star-dominated and blended detections. Structured visual inspection indicates that $54.5$–$62\%$ are consistent with genuine dual
nuclei, implying $\sim(1.4$–$1.8)\times10^{4}$ plausible systems. Cross-calibrating the YOLO separation against the deterministic GOTHIC centroid measurement and restricting to the compact regime ($d \le 6.87''$) gives a conservative subset of $\sim 13{,}672$ candidates, reaching calibrated separations of $\sim 0.56''$. Spectroscopy of the most compact ($\le 1$~kpc) systems shows they are dominated by passive, absorption-line
galaxies with no resolved double-peaked emission, so confirmation requires higher-resolution follow-up. The catalogue is a statistically refined list of candidates, not confirmed DAGN. Nonetheless, deep-learning detection substantially reduces contamination and expands the plausible DAGN census.
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All authors Bhavesh Mukheja, Snehanshu Saha, Anwesh Bhattacharya, Mousumi Das, Françoise Combes, Sudhanshu Barway
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
Searching for Solar-Basin Axionlike-Particle Decay with XMM-Newton Blank-Sky Observations
Bo Zhang, Chi Zhang, Lei Lei et al. (+4 more)
Axion-like particles (ALPs) bound in the solar gravitational field form the so-called ALP solar-basin. Since the two-
photon decay of non-relativistic particles is approximately isotropic, this population can be searched for using observations in the anti-solar direction. In this work, we propose a search strategy for narrow decay-line signals from the ALP solar basin using XMM-Newton blank-sky observations (XMM-BSOs) stacked spectra data taken in directions opposite to the Sun. By jointly fitting the signal and background model, we obtain limits on $g_{a\gamma\gamma}^{95}$ in the mass range $m_a=1.4\text{--}16~{\rm keV}$, with typical sensitivities of $g_{a\gamma\gamma}\sim10^{-10}\text{--}10^{-11}~{\rm GeV}^{-1}$. We have implemented the first anti-solar search for the solar basin, demonstrating that this strategy can exploit the stacked exposure of a large number of X-ray observations and provide a scalable analysis framework for future searches.
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All authors Bo Zhang, Chi Zhang, Lei Lei, Yang Yu, Guan-Shen Wang, Bing-Yu Su, Lei Feng
Astrophysics of Galaxies
Interplay of Compaction, Quenching, and Black Hole Growth in the Most Massive Galaxies since $z\sim5$: Insights from JWST and Chandra Data
Novan Saputra Haryana, Masayuki Akiyama, Abdurro'uf et al. (+16 more)
The buildup of dense stellar cores is expected to mark an important transition in the
star-formation and black-hole growth of massive
galaxies. Using spatially resolved spectral energy distribution (SED) fitting of James Webb Space
Telescope near-infrared imaging, combined with stacking analysis of Chandra X-ray data, we trace stellar mass buildup and average black hole
accretion in the most massive
galaxies at $z<5$, selecting 50 most massive
galaxies per
redshift bin at constant number density of $\sim4.4\times10^{-5}$ cMpc$^{-3}$. To robustly constrain central stellar populations, we separate active galactic
nuclei (AGN) components affecting the photometry using multi-band morphological decomposition and SED analysis. We find that the sample selected with constant number density exhibits evolutionary trend of rapid central compaction at $z\sim4$, during which the median central 1 kpc stellar mass increases by $\sim0.60$ dex over $\sim400$ Myr. The majority of X-ray detected AGN ($63\%\pm12\%$) are hosted by
galaxies undergoing the compaction, while we find neither individually detected X-ray sources nor a significant stacked X-ray signal at $z>4$, indicating that substantial average black-hole growth emerges primarily during, rather than before, the compaction. Following the compaction, central specific
star formation rates (sSFR) decline by $\sim1.24$ dex over $\sim700$ Myr at $z\sim3$ while remaining elevated
galaxy-wide, signaling the onset of inside-out quenching. Despite this central suppression, specific black hole
accretion rate remains coupled to the total sSFR. Our results suggest that dense-core formation in the most massive
galaxies marks the onset of inside-out quenching and a transition toward enhanced black-hole to stellar growth ratio.
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All authors Novan Saputra Haryana, Masayuki Akiyama, Abdurro'uf, Suchetha Cooray, Itsna Khoirul Fitriana, Dian P. Triani, Bovornpratch Vijarnwannaluk, Juan Pablo Alfonzo, Irham Taufik Andika, Muhammad Nur Ihsan Effendi, Ibnu Nurul Huda, Takumi Kakimoto, Anton Timur Jaelani, Ronaldo Laishram, Naoki Matsumoto, Abdurrahman Naufal, Lucky Puspitarini, Ryo Albert Sutanto, Hesti Retno Tri Wulandari
Astrophysics of Galaxies
Comparing the Nebular and Stellar Dust Attenuation Curves in Nearby Star-Forming Galaxies
Jong Chul Lee, Hyunjin Shim, Hyunmi Song et al. (+3 more)
Differences in the spatial distributions of
stars and ionized gas relative to dust in
galaxies imply that stellar and nebular dust attenuation curves need not be identical. Although stellar attenuation curves have been extensively studied, nebular attenuation curves remain less explored. In this work, we investigate nebular attenuation curves using Balmer line ratios for a sample of 90,958 nearby
star-forming
galaxies from the Sloan Digital Sky Survey with well-constrained stellar attenuation curves. In the H$\alpha$/H$\beta$ versus H$\alpha$/H$\gamma$ diagram, the nebular attenuation curves are, on average, significantly shallower than typical stellar attenuation curves, which can be qualitatively reproduced by source-dust
geometric effects. The nebular attenuation curve slopes show weak positive correlations with the stellar attenuation curve slopes and weak dependences on
galaxy properties that broadly follow those of the stellar attenuation curve slopes. These results suggest that nebular attenuation curves are distinct from stellar attenuation curves, while remaining consistent with a connection between them.
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All authors Jong Chul Lee, Hyunjin Shim, Hyunmi Song, Ho Seong Hwang, Woong-Seob Jeong, Jong-Ho Shinn
High Energy Astrophysical Phenomena
Spatially resolved spectral properties of M87* on event horizon scales
Shan-Shan Zhao, Ru-Sen Lu, Rocco Lico et al. (+2 more)
The supermassive black hole at the center of the nearby
radio galaxy M87 (M87*) is a
prime target for studying black hole physics. Spatially resolved spectral measurements on event-horizon scales can reveal the origin of the emission and probe the
plasma and gravitational environment in the immediate vicinity of the black hole. Here, we present an analysis of spectral properties based on nearly simultaneous high-resolution images at 3.5 mm (86 GHz) and 1.3 mm (230 GHz), obtained in 2018 with the Global Millimeter VLBI Array (GMVA) including ALMA and the Greenland
Telescope, and the Event Horizon
Telescope (EHT). We obtain the first spatially resolved spectral-index map ($S_\nu \propto \nu^\alpha$) within the compact region ($\leq 100\,\mu$as). We further detect a robust radial gradient with a modest rise in the inner $\lesssim 20~\mu$as (slightly inside the 1.3 mm ring), followed by a systematic decline at larger radii. The spectral index transitions from positive to negative values near $\sim 30~\mu$as, close to the 3.5 mm ring radius, consistent with frequency-dependent synchrotron opacity in the innermost
accretion flow. These results provide new observational constraints that can help discriminate between models of the horizon-scale emission and the launching of relativistic jets in M87*.
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All authors Shan-Shan Zhao, Ru-Sen Lu, Rocco Lico, Yuh Tsunetoe, Sijia Peng
Instrumentation and Methods for Astrophysics
Validation and extension of the PAWS Zemax model as a first step in the development of a Compact Arrayed Waveguide Stacked Multi-Object Spectrograph (CAWSMOS)
Fabienne Mangelsdorff, Andreas Stoll, Lars Zimmermann et al. (+4 more)
The linear size of a bulk optical astronomical spectrograph scales with the diameter of the primary mirror of the corresponding
telescope. As modern
telescopes continue to increase in aperture size, miniaturization of the spectrograph becomes crucial beyond the offered advantages in terms of multifunctional integration and
photon efficiency. The presented concept of development for a Compact Arrayed Waveguide Stacked Multi-Object Spectrograph (CAWSMOS) includes the design of the Arrayed Waveguide Grating (AWG) chips, the stacking frame and cross-dispersion optics for the imaging of multiple spectral orders per AWG. It aims to reduce the cost and size of astronomical spectrographs while also improving efficiency. This will bring the AWG technology closer to the realization of its full potential for ground based, airborne and spaceborne astronomical applications. Part of this development is an extension of the Potsdam Arrayed Waveguide Spectrograph (PAWS). To do that, the Zemax model is compared to PAWS calibration data, finding that the position can be matched with the measurement within 28 px in x and 18 px in y-direction. It also shows a discrepancy between the measured PSF size and the Zemax model of around factor five, and that the detector area can only partially accommodate a second chip.
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All authors Fabienne Mangelsdorff, Andreas Stoll, Lars Zimmermann, Stefan Lischke, Riya M. Pattery, Kalaga Madhav, Martin M. Roth
Earth and Planetary Astrophysics
Occultation of microlensed images by circum-lens disks: Implications for surveys
Elizabeth Bailey
Microlensing surveys typically apply automated criteria to exclude lightcurves that depart from time-symmetric and achromatic Paczyński curves. In surveys using such automated detection pipelines, occultation of microlensed images by circum-lens material could lead to underdetection or misclassification of ring- or disk-bearing compact object populations. This work characterizes the family of lightcurve morphologies by which uniform thin circum-lens disks of varying size and orientation, and low mass relative to their host lens, can intersect the ray paths produced during microlensing events. These morphology classes are paired with squared residuals relative to an unocculted lightcurve. We find that substantial deviations from an unocculted microlensing curve can occur across a wide range of parameter space. This effect holds relevance for free-floating
planets and brown dwarfs where disks or ring systems can be present. Another potential consideration is that disk-shaped
accretion flows onto primordial black holes (PBHs) during the
cosmic dark ages could have resulted in remnant quiescent disks of baryonic material. Pipelines should be designed to account for disk-bearing lens populations, opening previously underutilized avenues to potentially observe disks and rings in these contexts and ensuring populations are accurately characterized.
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Cosmology and Nongalactic Astrophysics
Projected Constraints on Primordial Black Holes from Scalar-Induced Gravitational Waves with Taiji
Yang Jiang, Chen Yuan and Qing-Guo Huang
Scalar-induced gravitational waves (SIGWs) provide a direct probe of the enhanced primordial
curvature perturbations that may also produce primordial black holes (PBHs). We forecast the capability of the space-based gravitational-wave observatory Taiji to search for an SIGW background generated by a broken-power-law
curvature spectrum. A signal-injection study is used to validate the analysis pipeline, after which a pure-noise realization is employed to derive projected upper limits on the
curvature-spectrum parameters. We translate these limits into constraints on the PBH abundance using the nonlinear compaction function, critical collapse, and the joint Gaussian distribution of the compaction amplitude and
curvature at its peak. The resulting projected $95\%$ upper limits on the PBH dark-matter fraction satisfy $f_{\mathrm{PBH}}^{95\%}<1$ over PBH masses from approximately $6.2\times10^{-18}\,M_\odot$ to $1.7\times10^{-8}\,M_\odot$. We compare the forecast with representative Hawking-evaporation and microlensing bounds. In part of the asteroid-mass interval, the projected Taiji limit is more restrictive than the current Subaru Hyper Suprime-Cam (HSC) microlensing constraint.
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High Energy Astrophysical Phenomena
Linking high-mass X-ray binaries to binary compact object mergers in Milky Way-like galaxies
Felipe Vivanco Cádiz, M. Celeste Artale, Nicola Masetti et al. (+5 more)
High-mass X-ray binaries (HMXBs) constitute a potential intermediate phase connecting massive stellar binaries to the formation of coalescing binary compact objects (BCOs). Yet, the specific circumstances that allow HMXBs to later develop into merging BCOs are still under debate. In this study, we focus on wind-fed HMXBs and investigate this link by generating synthetic catalogs with the population-synthesis code SEVN and assigning them to a sample of 66 Milky Way-like
galaxies. Using stellar particles drawn from the TNG50 cosmological simulation, we assign HMXBs according to particle mass, age, and
metallicity, and follow their subsequent
evolution to BCOs. In this way, our approach provides a realistic framework for modelling HMXBs in the Milky Way by explicitly accounting for the varied
metallicities and spatial distributions of binary systems. Our method recovers the spatial distribution inferred from the observed properties of Galactic HMXBs: their positions follow the spiral arms and agree with the measured radial profile. The age distribution aligns well with observations and shows that BH-HMXBs tend to be younger than NS-HMXBs. We find that the fraction of HMXBs that evolve into merging BCOs within a Hubble time for BH-HMXBs is ~0.2-3.2% (or ~0.3-5.4% when restricting to 10^35 <= L_X <= 10^40 erg s^-1), while for NS-HMXBs is ~3.6-23.4% (or ~3.5-26.0% with the same luminosity cut). We show that common envelope (CE) episodes and natal-kick magnitudes are the primary processes determining the number of merging systems. Successful BCO mergers are typically produced by systems that experienced significant orbital hardening (early CE), whereas stable mass transfer often yields wide, non-merging binaries unless extreme eccentricities are induced by kicks.
Metallicity plays a secondary but important role by modulating compact-remnant masses and wind-driven orbital widening.
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All authors Felipe Vivanco Cádiz, M. Celeste Artale, Nicola Masetti, Gaston Escobar, Giuliano Iorio, Ankit Kumar, Boyuan Liu, Michela Mapelli
Earth and Planetary Astrophysics
Linear Continuum Modelling to Explain The Majority of Bulk Features of Kuiper Belt Object Spectra
Wesley C. Fraser, Laura E. Buchanan, Ian Wong et al. (+2 more)
The first analyses of the James Webb Space
Telescope spectra of trans-Neptunian Objects (TNOs) revealed three discrete types of surfaces. This seems to contradict ground-based spectro-photometric
datasets, which suggest a continuum of colors with only two surface types. Here we present linear spectral modelling that reconciles these two results. In our model, the sole parameter is the object's optical slope, and the reflectance spectrum at all wavelengths is linearly proportional to that color, with the slope of that function evaluated from the spectra themselves. When applied to small (H>5 for H2O-types and H>4 for the merged sample of organic-rich and CO2-types) and distant (q>18 au) objects, we find that this model does a reasonable job of reproducing the overall spectral behavior of both samples. Bootstrapping simulations show that if the optical slope were not a good predictor of an object's spectrum, then finding an explained variance of the model that is better than observed occurred in 2.3% of realizations for the H2O-types and 0% of realizations for the organics sample. In a chi^2 sense, the optical color is a better predictor of most spectra as compared to the mean spectrum of a class. The trends of optical color and spectra band-areas exhibited for many key compositional materials are well reproduced, and demonstrate that those materials govern the overall spectral shape within a class. Importantly, these results require that within a given class, the band-areas of those key materials are predictable given only its optical color and its surface type. Unsurprisingly, our simple one-parameter model does not account for the full spectral diversity of TNOs. We speculate that albedo encapsulates much of the remaining diversity.
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All authors Wesley C. Fraser, Laura E. Buchanan, Ian Wong, Bryan Holler, Michael E. Brown