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Physics Astrophysics

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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Correlation between gravitational wave frequencies as a signature of new black hole physics

Ngo Phuc Duc Loc

We point out that for black holes (BH) of the same mass, despite of arising from two entirely different physical arguments, the peak frequency of the coarse-grained gravitational wave (GW) spectrum of gravitons $f_\text{peak}^\text{graviton}$ is very close to the peak frequency of the GW spectrum produced from binary BH mergers $f_\text{peak}^\text{merger}$. In particular, we find that $f_\text{peak}^\text{graviton}/f_\text{peak}^\text{merger}\approx 2.3$ independent from BH mass or population. If BHs are still evaporating, the peak frequencies scale as $\propto M_i^{-1}$ with $M_i$ is the initial BH mass. If BHs evaporated in the radiation (matter) dominated era, the peak frequencies scale as $\propto M_i^{1/2}$ ($\propto M_i$) respectively after taking into account redshift effect. Any deviation from the aforementioned magical ratio would indicate new BH physics. The sweetest frequency ballpark to look for this correlation is around $10^{14}\ \rm Hz-10^{20}\ \rm Hz$ where both GW spectra are allowed to have maximum amplitude. As a demonstration of what the new physics could be, we consider a phenomenological self-similar regular BH model of Hayward featuring a single hair parameter. The observed ratio of peak frequencies can be used to directly infer the hair parameter, along with crucial properties of the novel BH solution such as Hawking temperature, horizon size, and innermost stable circular orbit. We also comment on the pros and cons of correlating frequencies among other GW sources such as formation, population fluctuation, and sudden transition of adiabatic perturbation.
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High Energy Astrophysical Phenomena

Search for High-Energy Neutrinos from Infrared Flares

R. Abbasi, M. Ackermann, J. Adams et al. (+415 more)

IceCube has detected a diffuse flux of high-energy astrophysical neutrinos. While its astrophysical origin is unknown, a significant neutrino emission has been observed from the gamma-ray blazar TXS 0506+056 and the Seyfert galaxy NGC 1068. This suggests accretion by supermassive black holes as one of the candidate mechanisms of the diffuse neutrino flux. Indeed, external studies that made use of IceCube data identified candidate sources, including AT2019dsg, likely a stellar tidal disruption event (TDE), and AT2019fdr, associated with an active galactic nucleus (AGN). An additional study using an optically detected sample of 63 accretion flares revealed another candidate as a potential high-energy neutrino counterpart: AT2019aalc. All of these candidate transients exhibit strong dust echoes, characterized by delayed infrared (IR) emission relative to the initial optical outburst. We look for correlations between the most comprehensive catalog of infrared flares and 10 years of IceCube archival data. We perform a time-dependent stacking analysis testing 393 sources in the Northern Sky against 10 years of through-going tracks. No significant neutrino emission is observed, and we derive upper limits to constrain neutrino emission from this catalog. These limits are subsequently extrapolated to a population-level study. We find that the contribution of IR flares to the IceCube diffuse neutrino flux at 100 TeV is below 2.7% for a spectral index of 2.5.
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All authors R. Abbasi, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, J.M. Alameddine, S. Ali, N. M. Amin, K. Andeen, C. Argüelles, S. Athanasiadou, S. N. Axani, R. Babu, X. Bai, A. Balagopal V., S. W. Barwick, V. Basu, R. Bay, J. J. Beatty, J. Becker Tjus, J. Beise, C. Bellenghi, S. Benkel, S. BenZvi, D. Berley, E. Bernardini, D. Z. Besson, E. Blaufuss, L. Bloom, S. Blot, F. Bontempo, J. Y. Book Motzkin, C. Boscolo Meneguolo, S. Böser, O. Botner, J. Braun, B. Brinson, Z. Brisson-Tsavoussis, L. Brusa, R. T. Burley, D. Butterfield, K. Carloni, J. Carpio, N. Chau, Y. C. Chen, Z. Chen, D. Chirkin, S. Choi, A. Chubarov, B. A. Clark, D. A. Coloma Borja, A. Connolly, J. M. Conrad, D. F. Cowen, C. De Clercq, J. J. DeLaunay, D. Delgado, T. Delmeulle, S. Deng, P. Desiati, K. D. de Vries, G. de Wasseige, T. DeYoung, J. C. Díaz-Vélez, S. DiKerby, T. Ding, M. Dittmer, A. Domi, L. Draper, L. Dueser, D. Durnford, K. Dutta, M. A. DuVernois, T. Ehrhardt, L. Eidenschink, A. Eimer, C. Eldridge, P. Eller, E. Ellinger, D. Elsässer, R. Engel, H. Erpenbeck, W. Esmail, S. Eulig, J. Evans, P. A. Evenson, K. L. Fan, K. Fang, K. Farrag, A. Fattorini, A. R. Fazely, A. Fedynitch, N. Feigl, C. Finley, D. Fox, A. Franckowiak, S. Fukami, P. Fürst, J. Gallagher, A. Garcia, M. Garcia, E. Genton, L. Gerhardt, A. Ghadimi, C. Glaser, T. Glüsenkamp, J. G. Gonzalez, S. Goswami, A. Granados, D. Grant, S. J. Gray, S. Griffin, S. Griswold, K. M. Groth, D. Guevel, C. Günther, P. Gutjahr, C. Ha, A. Hallgren, F. Halzen, M. Handt, K. Hanson, J. Hardin, A. A. Harnisch, P. Hatch, A. Haungs, J. Häußler, K. Helbing, J. Hellrung, B. Henke, L. Hennig, F. Henningsen, L. Heuermann, R. Hewett, N. Heyer, S. Hickford, A. Hidvegi, C. Hill, G. C. Hill, R. Hmaid, K. D. Hoffman, A. Hollnagel, D. Hooper, S. Hori, K. Hoshina, M. Hostert, W. Hou, M. Hrywniak, T. Huber, K. Hultqvist, K. Hymon, A. Ishihara, W. Iwakiri, M. Jacquart, S. Jain, O. Janik, M. Jansson, M. Jin, N. Kamp, D. Kang, W. Kang, A. Kappes, L. Kardum, T. Karg, A. Karle, A. Katil, M. Kauer, J. L. Kelley, B. Kern, M. Khanal, A. Khatee Zathul, A. Kheirandish, T. Kim, H. Kimku, F. Kirchner, J. Kiryluk, C. Klein, S. R. Klein, Y. Kobayashi, S. Koch, A. Kochocki, R. Koirala, H. Kolanoski, T. Kontrimas, L. Köpke, C. Kopper, D. J. Koskinen, P. Koundal, M. Kowalski, A. Kravka, N. Krieger, T. Krishnan, K. Kruiswijk, E. Krupczak, E. Kun, N. Kurahashi, C. Lagunas Gualda, L. Lallement Arnaud, M. J. Larson, F. Lauber, J. P. Lazar, K. Leonard DeHolton, A. Leszczyńska, C. Li, J. Liao, C. Lin, Q. R. Liu, Y. T. Liu, M. Liubarska, C. Love, L. Lu, F. Lucarelli, W. Luszczak, Y. Lyu, M. Macdonald, F. Machingal, E. Magnus, Y. Makino, E. Manao, S. Mancina, A. Mand, I. C. Mariş, S. Marka, Z. Marka, I. Martinez-Soler, R. Maruyama, J. Mauro, F. Mayhew, F. McNally, K. Meagher, A. Medina, M. Meier, Y. Merckx, L. Merten, J. M. Mitchell, S. Mondal, T. Montaruli, R. W. Moore, Y. Morii, A. Mosbrugger, D. Mousadi, E. Moyaux, T. Mukherjee, M. Nakos, U. Naumann, R. Neshat, L. Neste, M. Neumann, M. U. Nisa, K. Noda, A. Noell, A. Novikov, A. Obertacke, V. O'Dell, A. Olivas, R. Orsoe, J. Osborn, E. O'Sullivan, B. Owens, V. Palusova, H. Pandya, A. Parenti, C. Parisel, N. Park, V. Parrish, E. N. Paudel, L. Paul, C. Pérez de los Heros, T. Pernice, T. C. Petersen, J. Peterson, S. Pick, M. Plum, A. Pontén, V. Poojyam, B. Pries, R. Procter-Murphy, G. T. Przybylski, L. Pyras, C. Raab, J. Rack-Helleis, N. Rad, M. Ravn, K. Rawlins, Z. Rechav, A. Rehman, R. Reimann, I. Reistroffer, E. Resconi, C. D. Rho, W. Rhode, L. Ricca, B. Riedel, A. Rifaie, E. J. Roberts, S. Rodan, M. Rongen, A. Rosted, C. Rott, T. Ruhe, L. Ruohan, D. Ryckbosch, J. Saffer, D. Salazar-Gallegos, P. Sampathkumar, A. Sandrock, G. Sanger-Johnson, M. Santander, S. Sarkar, M. Scarnera, M. Schaufel, H. Schieler, S. Schindler, L. Schlickmann, B. Schlüter, F. Schlüter, N. Schmeisser, T. Schmidt, F. Schmitt, A. Scholz, F. G. Schröder, S. Schwirn, S. Sclafani, D. Seckel, L. Seen, M. Seikh, S. Seunarine, P. A. Sevle Myhr, R. Shah, S. Shah, A. Sharma, S. Shefali, N. Shimizu, M. Shin, R. Singh, B. Skrzypek, R. Snihur, J. Soedingrekso, D. Soldin, P. Soldin, G. Sommani, D. Song, C. Spannfellner, G. M. Spiczak, C. Spiering, J. Stachurska, M. Stamatikos, T. Stanev, T. Stezelberger, T. Stürwald, T. Stuttard, G. W. Sullivan, I. Taboada, S. Ter-Antonyan, A. Terliuk, A. Thakuri, P. Thelen, M. Thiesmeyer, W. G. Thompson, J. Thwaites, W. Tian, S. Tilav, K. Tollefson, J. A. Torres, S. Toscano, D. Tosi, K. Upshaw, A. Vaidyanathan, N. Valtonen-Mattila, J. Valverde, J. Vandenbroucke, T. Van Eeden, N. van Eijndhoven, L. Van Rootselaar, J. van Santen, J. Vara, F. Varsi, M. Velazquez, M. Venugopal, M. Vereecken, S. Vergara Carrasco, S. Verpoest, A. Vijai, J. Villarreal, C. Walck, A. Wang, E. H. S. Warrick, C. Weaver, P. Weigel, A. Weindl, J. Weldert, A. Y. Wen, C. Wendt, J. Werthebach, M. Weyrauch, N. Whitehorn, C. H. Wiebusch, D. R. Williams, L. Witthaus, J. Woodward, G. Wrede, X. W. Xu, J. P. Yanez, Y. Yao, E. Yildizci, S. Yoshida, F. Yu, S. Yu, T. Yuan, S. Yun-Cárcamo, A. Zander Jurowitzki, A. Zegarelli, S. Zhang, Z. Zhang, P. Zhelnin, P. Zilberman, C. Zilleruelo Cañas, M. Zimmermann

Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

All Quiet on the Vector Front: Scalar Growth and Perturbative Control in Horndeski–Weyl-squared Gravity

Antonio De Felice, Guillem Domènech and Jan Tränkle

Higher-order curvature corrections to general relativity arise naturally in many fundamental theories and provide phenomenologically interesting low-energy effective field theories. However, higher-derivative terms can introduce ghost modes, which call the validity of such models into question. Here, we thoroughly investigate the classical linear stability of the most general second-order scalar-tensor theory, namely the Horndeski theory of gravity, augmented by a Weyl-squared term in the action. We consider shift-symmetric de Sitter and power-law FLRW backgrounds and study the evolution of linear perturbations. Vector perturbations are free of gradient and tachyonic instabilities for a positive Weyl-induced mass squared. Tensor perturbations necessarily contain a ghost; their superhorizon branches are bounded, while a frozen-background calculation identifies a separate finite-momentum stability condition. The scalar sector instead contains a growing long-wavelength branch for all expanding backgrounds we consider, which is inherited by at least one of the gauge-invariant Bardeen potentials. We show that this growth enters the Bardeen potentials through an inverse-gradient factor $a^2/k^2$: the dynamical scalar fields remain bounded on the inflationary backgrounds, the direct contribution of the growing shear to the clock-matched tidal field cancels, and the electric part of the Weyl tensor decays. We discuss the implications of our results for perturbative control and for the phenomenological viability of theories including quadratic curvature corrections.
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Instrumentation and Methods for Astrophysics

R&D activity in INAF on light instrumentation for continuous optical turbulence monitoring

Camilo Weinberger Elena Masciadri, Luca Carbonaro, Marlene de Sepibus et al. (+4 more)

Measurements of optical turbulence are essential in both ground-based astronomy and free-space optical communication systems contexts for multiple reasons including supporting and optimizing Adaptive Optics. Similarly, forecasting these parameters is highly valuable for planning observational campaigns; however, it requires at least two years of continuous data to generate a reliable training dataset. The most commonly used instruments to monitor continuously the optical turbulence include DIMM, MASS, SLODAR, RINGSS sensors. The Arcetri team is leading two operational forecast systems for two different Observatories: ALTA above LBT, and FATE above VLT. Both systems are in continuous evolution and obviously forecast performances depend also on available measurements. Our long-term goal is to develop our own instruments to obtain continuous measurements directly from local observations. In this work, we present an automated system designed for continuous seeing measurements using multiple sensors. This portable station integrates a Cyclope, a RINGSS unit, a scintillometer which operate together to provide comprehensive night-time atmospheric information. We will compare the performance of low-cost sensors, such as the Cyclope and the scintillometer, with that of the RINGSS turbulence profiler, which has been fully installed and programmed by our team in collaboration of LBT team. A dedicated insturment for night and day-time measurements is planned for near future. This system incorporates a fully automatic on-site system that monitors operational status, delivers real-time information on sensor conditions and measurements, and manages synchronization with the data storage unit. The system's real-time acquisition capability enables continuous turbulence analysis, supports R&D activities, facilitates local data generation, and allows on-site testing of forecasting methodologies.
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All authors Camilo Weinberger Elena Masciadri, Luca Carbonaro, Marlene de Sepibus, Fernando Pedichini, Ciro Del Vecchio, Christian Veillet, Sam Ragland

Astrophysics of Galaxies

Uncovering the origin of complex velocity distributions in edge-on disc galaxies

Sophie Townson, Marie Martig, Robert J. J. Grand et al. (+3 more)

Stellar line-of-sight velocity distributions are a powerful tool for studying galaxy kinematics and formation history, with multiple-peaked LOSVDs often indicating the presence of complex kinematic components. We extract stellar LOSVDs across the disc of a simulated spiral galaxy viewed edge-on, and study how often and why we see multiple-peaked LOSVDs. We find that the multiple-peaked LOSVDs are mainly found close to the midplane because they result from the presence of spiral arms. This is not because the spiral arms have significantly different kinematics to the disc, but because they correspond to over-densities. Variations in the number of arms present along a line-of-sight create variations in the number of peaks in LOSVDs. This can be used to quantify the strength of the spiral arms above the midplane, and how the thickness of spiral arms vary across the disc. We find that the commonly used fourth order Gauss-Hermite moment, $h_4$, is negative in the regions where there are multiple-peaked LOSVDs, and hence traces spiral arms. Finally, we discuss the observability of the multiple-peaked regions and their associated $h_4$ measurements with current integral field spectrographs. We find that the spectral resolution of MUSE might not be high enough to uncover multiple peaks in LOSVDs when they result from spiral arms, but should allow for identification of the regions of negative $h_4$. On the other hand, higher resolution spectrographs like KOALA and WEAVE may be able to recover multiple peaks in LOSVDs, representing a promising avenue for characterising spiral arms in edge-on disc galaxies.
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All authors Sophie Townson, Marie Martig, Robert J. J. Grand, Prashin Jethwa, Jesús Falcón-Barroso, Timothy A. Davis

High Energy Astrophysical Phenomena

Optical constraints on intranight variability in TeV HBLs from a two-year Asiago Schmidt monitoring campaign

Domenico Impiombato, Giacomo Bonnoli, Elisa Prandini et al. (+2 more)

We present a two-year homogeneous optical monitoring campaign of three TeV-emitting high-synchrotron-peaked BL Lac objects, 1ES 1959+650, H 1426+428, and PG 1553+113, carried out with the Asiago Schmidt 67/92 cm telescope. TeV blazars are key targets in high-energy astrophysics, relevant for relativistic jet physics, particle acceleration, multiwavelength variability studies, and, in selected cases, multimessenger programmes. In this context, dense optical monitoring provides a low-energy synchrotron tracer of jet activity over temporal baselines that are difficult to cover continuously with high-energy facilities. The dataset consists of more than 17,000 R- and I-band photometric measurements obtained over 957 source-filter observing sessions between 2024 February 1 and 2026 January 31, for a total monitoring time of about 420 h. We applied a uniform differential-photometry and classical F-test framework based on two independent comparison-star pairs. Robust IDV is detected only in H 1426+428, with 15 out of 43 analysed sessions classified as variable in the R band and 5 out of 40 in the I band. No significant IDV is detected in 1ES 1959+650 or PG 1553+113 within the adopted statistical framework. For H 1426+428, the corresponding duration-weighted duty cycles, computed using only variable sessions with a measured local characteristic timescale, are 28.0% in the R band and 7.0% in the I band. The inferred local extrapolated doubling/halving timescales are of the order of 5-15 min in the observer frame. These results indicate that rapid optical synchrotron variability in TeV HBLs is intermittent and state-dependent. They also show that robotic small- and medium-aperture optical facilities can provide valuable long-term support for high-energy monitoring programmes by supplying dense, uniform, and repeatable optical coverage.
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All authors Domenico Impiombato, Giacomo Bonnoli, Elisa Prandini, Luca Zampieri, Irene Albanese

Solar and Stellar Astrophysics

HD 152384: A 5 Myr old debris disk system showing a gaseous ring of refractory elements at the dust sublimation radius

Mario van den Ancker, Daniela Iglesias, Olja Panić et al. (+2 more)

Context: Circumstellar gas around young stars provides key insights into planet formation and disk evolution. HD 152384, a young (5 Myr) A0 V star in Sco-Cen, shows hybrid-disk traits: a modest infrared excess from small dust grains and atomic emission lines dominated by refractory elements, but its disk structure and origin remain unclear. Aims: We characterise the kinematics and excitation of the circumstellar gas around HD 152384 and constrain the physical properties of its emitting region. Methods: We use new high-resolution optical and near-infrared VLT/UVES and VLT/CRIRES spectra to re-examine the circumstellar environment of HD 152384, previously suggested to host a broad, gas-rich disk. Results: The observations reveal 74 narrow, double-peaked emission lines of Fe, Mg, Si, and Ca, with similar profiles and a 103 km/s peak separation. Keplerian modelling places the gas in a geometrically thin ring at 0.09-0.12 au, close to the dust sublimation radius (0.10-0.14 au for a sublimation temperature of about 1500 K). The Fe I emission is optically thick, whereas the optically thin Mg I lines imply 2.2 x 10^22 kg (3.6 x 10^-3 Earth masses) of magnesium gas in the ring. Conclusions: The dust and gas properties are consistent with a secondary origin involving collisions of rocky planetesimals. We propose that small collision-produced dust grains spiral inward and sublimate near the dust sublimation radius, accumulating atomic gas there. HD 152384 thus represents a young analogue of gas-bearing debris disks such as Beta Pictoris and gaseous debris disks around metal-polluted white dwarfs, offering a new window on the early violent processing of rocky planetesimals.
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All authors Mario van den Ancker, Daniela Iglesias, Olja Panić, Monika Petr-Gotzens, Miguel Vioque

Solar and Stellar Astrophysics

Flares and flux ropes: an entangled story

Rony Keppens, Yang Guo and Wenzhi Ruan

Solar flares serve as standard candles for all magnetic-reconnection-based energy releases, and their consequences into the heliosphere can be modeled from first principles. This review presents the latest developments in modeling solar flares and their associated flux rope expulsions with state-of-the-art multidimensional magnetohydrodynamic (MHD) descriptions. Observationally established ingredients beyond a single-fluid, thermal plasma evolution have been incorporated to varying degrees, and we highlight self-consistent efforts realized in "standard flare" setups.
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Solar and Stellar Astrophysics

Tracking a solar energetic eruption and associated energetic particles from Sun to spacecraft

D. E. Morosan, M. Baumgartner-Steinleitner, K. Bhandari et al. (+17 more)

Context. Solar energetic particles (SEPs) in the heliosphere are produced by flaring processes on the Sun or shocks driven by coronal mass ejections (CMEs). Electrons, in particular, are regularly detected remotely as electromagnetic radiation (X-rays or radio emission), which they generate through various processes, as well as in situ by spacecraft monitoring the Sun and the heliosphere. Aims. We aim to combine remote-sensing and in situ observations of an energetic solar eruption to link energetic processes in the solar corona to energetic particles observed in situ in the heliosphere. This will be done using the tools developed in the Horizon Europe SOLER project. Methods. Here, we investigate a solar energetic eruption at the Sun together with its associated signatures of accelerated electrons observed at radio and X-ray wavelengths and combine these remote observations to in situ particles observed by spacecraft on 10 March 2024. These observations are combined with a magneto-hydrodynamic (MHD) model of the solar corona in order to make the remote to in situ connections. Results. We observe a high-energy SEP event at multiple spacecraft (>25 MeV protons and 1 MeV electrons), despite the event being associated with a slow white-light CME. Remote observations of the Sun show that the event was associated with a fast large scale coronal wave (1400 km/s) and also multiple regions where electrons are accelerated around this large scale wave observed as type II radio bursts. In addition, we observe a strong coronal dimming away from the main flaring region, providing evidence of field lines getting opened to interplanetary space, dislocated from the flare site.
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All authors D. E. Morosan, M. Baumgartner-Steinleitner, K. Bhandari, N. Dresing, G. Farwa, J. A. J. Mitchell, C. Palmroos, A. Razquin, J. Zhang, C. Briand, K. Dissauer, A. Fedeli, J. Gieseler, E. K. J. Kilpua, S. Normo, J. Pomoell, D. J. Price, A. M. Veronig, A. Warmuth, R. Vainio

High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Testing Charged Black Holes Embedded in Anisotropic Matter and Surrounded by Plasma through Gravitational Lensing: Bounds from the Sloan Lens ACS Survey

Ritesh Pandey, Shubham Kala, Amare Abebe et al. (+2 more)

We investigate weak gravitational lensing by a charged black hole surrounded by anisotropic matter, described by the two-component Kiselev metric, and immersed in a homogeneous plasma. We first examine the black hole geometry and horizon structure and then derive the weak-deflection angle from the Hamiltonian description of light propagation in plasma, using an expansion with a fixed turning point that we verify against direct numerical integration. Using the gravitational lens equation, we obtain the Einstein-ring angle, the image positions, the total magnification and the fractional magnifications of the primary and secondary images. We then confront the model with the Einstein radii of two galaxy-scale lenses of the Sloan Lens ACS Survey, J0008$-$0004 and J0029$-$0055. Because the Einstein angle cannot be smaller than the reduced deficit deflection, the observed radii give the mass-independent bounds $K<6.5\times10^{-6}$ and $K<4.2\times10^{-6}$, respectively. The charge correction to the Einstein radius is suppressed by $r_s/R_E\approx 5\times10^{-6}$ and is unobservable, while the plasma parameter at the optical wavelengths of the SLACS imaging is of order $10^{-22}$ and cannot be constrained. Our results show that galaxy-scale strong lensing data place stringent limits on anisotropic matter surrounding the lens, whereas plasma effects can be probed only at low radio frequencies.
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All authors Ritesh Pandey, Shubham Kala, Amare Abebe, Hemwati Nandan, G. G. L. Nashed

Solar and Stellar Astrophysics

Stationary Resistive MHD Solutions Near an Isolated Three-Dimensional Magnetic Null

Kuljeet Singh Saddal, Dieter H. Nickeler, Rodrigo Meneses Pacheco et al. (+1 more)

Magnetic null points define the magnetic field topology in stellar coronae, planetary magnetospheres, and astrospheres, and are commonly associated with magnetic reconnection. We investigate the local structure of stationary three-dimensional (3D) resistive, incompressible magnetohydrodynamic (MHD) flows in the vicinity of an isolated magnetic null and an isolated velocity stagnation point, assuming that the two nulls are colocated. The governing MHD equations are solved self-consistently using a first-order local expansion of the magnetic and velocity fields about the null. For any given magnetic-null configuration, the equations admit a two-parameter family of stationary solutions, comprising multiple solution branches with distinct velocity topologies. Along these families, the velocity-null polarity can change at bifurcation points where the flow becomes effectively 2.5D. A single magnetic null can therefore support positive-radial, negative-radial, and spiral stagnation flows, with qualitatively different inflow, outflow, and rotational properties. The associated pressure and resistivity distributions are likewise determined self-consistently and vary across the solution family, demonstrating that they are coupled to the flow topology rather than prescribed independently. The generic solutions do not require the velocity and magnetic separatrices to coincide, allowing plasma to cross the magnetic fan separatrix and providing a local reconnective flow. These results demonstrate that, in the presence of nonuniform resistivity, the magnetic topology alone does not uniquely determine the associated stationary flow, pressure, or resistivity structure around a 3D magnetic null, revealing the nonlinear feedback between all macroscopic variables and resistivity. The constant-resistivity field-aligned and spiral field-crossing solutions identified previously are recovered as special cases.
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All authors Kuljeet Singh Saddal, Dieter H. Nickeler, Rodrigo Meneses Pacheco, Michaela Kraus

Cosmology and Nongalactic Astrophysics

Testing Departures from the $\Lambda$CDM model in f(T) Gravity with DESI DR2

Jie Zheng, Mingzhi Wang and Ming Zhang

Recent analyses combining DESI baryon acoustic oscillation (BAO) measurements with other cosmological observations have reported indications of departures from the $\Lambda$CDM model within dynamical dark energy scenarios. We investigate whether such deviations are reproduced consistently in $f(T)$ gravity and whether they persist when different cosmological observations are combined. Using the DESI DR2 BAO measurements, Cosmic Microwave Background (CMB), and Pantheon+ Type Ia Supernovae (SNe Ia) sample, we constrain three representative $f(T)$ models: the power-law, exponential, and hyperbolic-tangent models. We compare the constraints obtained from different combinations of data, distinguishing changes in marginalized parameter distributions from changes in the relative statistical performance of the models. For the power-law model, the mild deviation from the $\Lambda$CDM model obtained from BAO+CMB disappears after the SNe Ia data are included. In contrast, the exponential model retains a preference for a nonzero deformation parameter in the full analysis, while the allowed parameter space of the hyperbolic-tangent model changes substantially after the CMB distance priors are included. Importantly, the parameter-level deviation found for the exponential model does not lead to a clear statistical preference over the $\Lambda$CDM model according to the information criteria, whereas the hyperbolic-tangent model shows a poorer statistical performance for the combined data. Despite these differences in the model constraints, the inferred transition redshift $z_T$ remains relatively stable among the three models and data combinations. Our results show that the departures from the $\Lambda$CDM model indicated by DESI analyses are not a generic feature of $f(T)$ gravity, but depend strongly on the specific modified gravity parameterization and on the combination of cosmological observations.
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Solar and Stellar Astrophysics

Nova shells in 3D: I. A catalog of integral field spectroscopic observations

Janis B. Rodríguez-González, Edgar Santamaría, Martin A. Guerrero et al. (+1 more)

Classical novae eject material during thermonuclear eruptions on accreting white dwarfs, forming expanding shells whose structures and kinematics provide insights into the eruption mechanism and binary interaction. However, their intrinsic three-dimensional (3D) structures remain poorly constrained. We present the first 3D catalog of nova shells based on integral field spectroscopy, enabling us to investigate their structures beyond projection effects. We compiled observations of 19 nova shells obtained with MUSE at the VLT, complemented by new MEGARA observations at the GTC and WEAVE observations at the WHT. We constructed 3D visualizations of selected emission lines to explore the diversity of shell morphologies and kinematics. The shells reveal a wide variety of structures, including ellipsoidal or spherical shells, rings, bipolar features, and clumpy or irregular components, many of which are not apparent in 2D projections. Approximately 60% of the sample exhibits predominantly ellipsoidal or spherical shapes, while about 30% shows ring-like or bipolar structures. Several objects display strong line-dependent morphological differences, with [O III] or [N II] tracing distinct kinematic components from those seen in H${\alpha}$. Compared with imaging studies, integral field spectroscopy reveals a larger fraction of bipolar or toroidal shells. The differences between emission lines highlight the diverse excitation mechanisms and physical conditions within the ejecta. Finally, comparing expansion velocities in the plane of the sky and along the line of sight suggests low intrinsic aspect ratios, consistent with estimates from projected shell shapes.
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All authors Janis B. Rodríguez-González, Edgar Santamaría, Martin A. Guerrero, Jesús A. Toalá

Astrophysics of Galaxies

Galactic Morpholography: Linking present-day galaxy compactness to assembly history and relic formation in the COLIBRE simulations

Maximilian Zemsch, Claudia D.P. Lagos, Chiara Spiniello et al. (+11 more)

Compactness is widely used to identify candidate relic galaxies, the largely untouched survivors of the first compact massive galaxies. Yet relicness is an evolutionary rather than structural property. Using the COLIBRE cosmological hydrodynamical simulations, we test whether present-day structure traces galaxy formation and assembly histories. Six complementary tracers (stellar age, metallicity, [Mg/Fe], sSFR, velocity dispersion and ex-situ mass fraction) vary coherently across the stellar mass-size plane and independently identify a characteristic compactness scale of $\log_{10}(\Sigma_{1.5,\mathrm{crit}}/(\mathrm{M}_\odot\mathrm{kpc}^{-1.5}))=9.75\pm0.10$. We term this mapping between present-day structure and assembly history morpholography. Combining this threshold with the Degree of Relicness ($\mathrm{DoR}>0.6$), which quantifies early and rapid star formation, we distinguish compact from ancient galaxies and identify 267 relic candidates at their intersection. Ancient galaxies span nearly the full ex-situ-fraction range, from predominantly in-situ formation to substantial merger-driven growth. Relic candidates are concentrated at stellar masses of $\approx 10^{10}$-$10^{11}$ solar masses, host black holes that lie $\approx 0.25$-$2.5$ dex above the median black-hole-stellar-mass relation, and are predominantly satellites (76%), preferentially in cluster environments. Only $\approx 3$% show evidence of strong tidal stripping, suggesting that environment primarily preserves rather than creates relic-like systems. Approximately one third (87/267) are direct descendants of the $z=2$ massive quiescent galaxies identified in COLIBRE. Present-day structure thus retains a statistical fossil record of assembly history, supporting morpholography as a link between nearby galaxies and the early Universe.
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All authors Maximilian Zemsch, Claudia D.P. Lagos, Chiara Spiniello, Michele Cappellari, Ángel Chandro-Gómez, Katy L. Proctor, Evgenii Chaikin, Johanna Hartke, Filip Huško, Sylvia Ploeckinger, Alexander J. Richings, Mahsa Sanati, Joop Schaye, James W. Trayford

Astrophysics of Galaxies

The physical and chemical structure of TMC-1. The spatial distribution and excitation conditions of carbon, oxygen, and sulfur bearing species: Depletion of CO and CS

J. Cernicharo, B. Tercero, N. Marcelino et al. (+3 more)

We present a detailed study of the physical and chemical structure of TMC-1 from the observed spatial distribution of HC3N, NNH+, CN, and their isotopologues, the O-bearing species C18O, C17O, CH3OH, CH3CHO, and H2CO, and the S-bearing species CS, HCS+, H2CS, and H2CCS. The well known filamentary structure of TMC-1 can be interpreted as a single cloud with a velocity gradient perpendicular to the filament, or less likely as due to the alignment of three independent clouds in the line sight with velocities of 5.3-5.7, 5.7-5.9, and 5.9-6.3 km/s. The main contribution to the emission of all studied C-bearing species is found at 5.83 kms/s. We conclude that the three velocity components are dynamically connected and that C-bearing molecules show a different behavior of their abundances compared to O-bearing species, which have emission peaks at 5.7 and 6.25 km/s, and appear at different spatial locations than cyanopolyynes and CnH and CnN radicals. The detection of 13C18O, with exactly the same line profile than that of C18O and C17O, excludes the possibility that the decrease of their emission at 5.83 km/s, could be due to self absorption or absorption by a foreground cloud component. Hence, as indicated by the spatial distribution of C18O and C17O, CO is significantly depleted at the velocities and positions where the emission of the carbon chains and radicals is found. This suggests that the emission of O-bearing species is coming from the external layers of the carbon-rich filaments. A comparison between S-bearing species and other molecules indicates that CS, CCS, HCS+, and H2CS are significantly depleted in the zone of CO depletion. A clear increase of the deuteration of several molecular species is found in the zones where CO and CS are depleted.
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All authors J. Cernicharo, B. Tercero, N. Marcelino, G. Esplugues, G. Molpeceres, M. Agúndez

Instrumentation and Methods for Astrophysics · Cross-listed from gr-qc

Quantum noise and torque correlations in a torsion-bar Sagnac speed meter

Yuki Inoue, Mario Onglao, Daiki Tanabe et al. (+3 more)

Quantum fluctuations entering through weakly transmitting mirrors can limit a torsion-bar Sagnac speed meter for low-frequency gravitational-wave detection, even when its optical layout suppresses radiation-pressure back action. We show that, in the Cryogenic sub-Hz cROss torsion bar detector with quantum NOn-demolition Speed meter (CHRONOS), vacuum fields entering from behind the end and middle test masses can dominate the low-frequency quantum noise despite cancellation of the torques on opposite ends of each bar. For a reference configuration with mirror power transmissions of only $10^{-7}$, these fields contribute $89.7\%$ of the total quantum-noise power spectral density at 0.1 Hz. Omitting them would underestimate the amplitude spectral density by a factor of 3.11. Our input-output model connects the correlations produced by successive optical interactions to the forces on each bar and the measured signal. This connection shows why strong torque cancellation does not, by itself, ensure a corresponding improvement in detector sensitivity. Replacing mirror transmission with absorption at fixed reflectivity leaves the excess quantum noise essentially unchanged for the two operating points studied. The predicted signal response and quantum noise agree with independent FINESSE 3 calculations as recycling detuning and homodyne angle are varied. These results establish rear vacuum fields as a limiting noise source in this torsion-bar speed meter and provide quantitative requirements for its mirror and readout design.
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All authors Yuki Inoue, Mario Onglao, Daiki Tanabe, Masashi Hazumi, Vivek Kumar, Apimook Watcharangkool

Astrophysics of Galaxies

The Role of Environment in Shaping the Assembly Timelines of Massive Quiescent Galaxies at Cosmic Noon

Tianmu Gao, J. Trevor Mendel, Letizia Bugiani et al. (+10 more)

JWST observations of massive quiescent galaxies (MQGs) at $z\sim2$ have revealed diverse star formation histories (SFHs). In this letter, we investigate whether these variations are linked to the environment in which MQGs reside, as quantified by the host dark matter halo mass. We identify 12 MQGs from a representative sample of galaxies at $1.6<z<3.5$ obtained by the Blue Jay survey, a JWST Cycle 1 program, and infer their SFHs via modelling of the deep NIRSpec medium-resolution spectra along with multi-band photometry. By correlating the formation and quenching epochs of individual MQGs with their respective host halo masses from the 3D-HST survey, we find that after accounting for the redshift range of the sample ($1.8<z<2.5$), MQGs in more massive haloes formed at significantly earlier cosmic epochs. Meanwhile, although these galaxies also quenched earlier overall, the scatter in quenching epochs across similar halo masses indicates that the quenching process likely involves other contributing factors and is not solely determined by halo mass.
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All authors Tianmu Gao, J. Trevor Mendel, Letizia Bugiani, Minjung Park, Sirio Belli, Joel Leja, Claudia del P. Lagos, Amir H. Khoram, Rebecca L. Davies, Razieh Emami, Gabriel Maheson, Anita Zanella, Benjamin P. Collins

Astrophysics of Galaxies

Sleeping or Dead? Probing the Quenching Mechanism of JWST Dormant Galaxies at z > 3 with ALMA

Mengyuan Xiao, Songnan Qi, Pascal A. Oesch et al. (+16 more)

JWST has revealed a population of "dormant” galaxies at z>3 with strong Balmer breaks and weak emission lines, whose star formation appears to have declined only recently. Whether these galaxies are undergoing a lasting transition toward quiescence or merely experiencing a temporary suppression of star formation remains unclear. We investigate their molecular gas content using archival ALMA observations of [CII]158um and CO rotational transitions. Starting from all publicly available JWST/NIRSpec prism observations and using joint spectrophotometric fitting, we construct a parent sample at z>3 and log(Mstar/Msun)>9.5 in the ALMA-accessible COSMOS, UDS, and GOODS-South fields. Our final sample comprises 7 dormant galaxies and 15 quiescent galaxies with ALMA constraints on their molecular gas content (mostly 3 sigma upper limits). We find that dormant galaxies exhibit systematically lower star formation rates averaged over the past 10Myr (SFR10Myr) than over the past 100Myr (SFR100Myr), supporting a recent rapid decline in their star formation. For the ~70% of the sample with sufficiently constraining ALMA observations, their molecular gas fractions lie at least ~0.3-2dex below those expected for main-sequence galaxies. Moreover, the molecular gas fractions of dormant galaxies show no systematic difference from those of quiescent galaxies in our sample. This indicates that dormant galaxies have already reached a gas-poor state shortly after quenching and favors a scenario in which the rapid shutdown of star formation is associated with depletion or removal of the molecular gas reservoir, rather than primarily with suppressed star formation efficiency while retaining a substantial molecular gas reservoir. Our results suggest that, if no substantial gas replenishment occurs in the future, dormant galaxies are more consistent with becoming "dead” than with being temporarily "sleeping”.
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All authors Mengyuan Xiao, Songnan Qi, Pascal A. Oesch, Longji Bing, Miroslava Dessauges-Zavadsky, Andreas L. Faisst, Mahsa Sanati, Rashmi Gottumukkala, Gabriel Brammer, David Elbaz, Robert Feldmann, Yoshinobu Fudamoto, Lucas C. Kimmig, Benjamin Magnelli, Rui Marques-Chaves, Anurag Amol Sawarkar, Sune Toft, Francesco Valentino, Christina C. Williams

Instrumentation and Methods for Astrophysics

RPCA: a Resolved PSF reconstruction method for undersampled images

Lin Nie, Huanyuan Shan, Guoliang Li et al. (+11 more)

The Point-Spread Function (PSF) is a critical component in various astrophysical research areas, including galaxy morphology, photometric redshift determination, and weak lensing studies. As the next generation of space telescopes prepares for operations, including the China Space Station Telescope (CSST), accurate PSF modeling has become increasingly important. However, accurately modeling the PSF remains challenging, particularly for poorly sampled images. To construct reliable PSF models based on star images, we aim to develop a novel and robust method, which accounts for the pixel integration effect in modeling for reconstructing high-resolution PSFs from undersampled or poorly resolved images. In this paper, we present Resolved Principal Components Analysis (RPCA), a novel approach that accounts for pixel integration effects to enable the direct reconstruction of resolved PSFs from undersampled images via an Expectation-Maximization PCA (EMPCA) technique. Our method has been tested on a simulated PSF dataset for the China Space Station Telescope (CSST), where both observational and detector-induced effects were considered during simulation. The results demonstrate that RPCA achieves superior precision in PSF shape parameters compared to existing methods such as Multi-CCD (MCCD), Resolved Components Analysis (RCA), and PSFEx. Notably, RPCA {could reduce the bias of $\Delta R^2/R^2$ by approximately one order of magnitude with respect to MCCD, RCA and PSFEx. RPCA exhibits robust stability under realistic observational conditions, including varying signal-to-noise ratios (SNRs) and contamination from cosmic rays and bad pixels. This suggests that RPCA could be a promising candidate for future CSST PSF modeling efforts.
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All authors Lin Nie, Huanyuan Shan, Guoliang Li, Tobías I. Liaudat, Chengliang Wei, Peng Wei, Tianmeng Zhang, Hekun Li, Lei Wang, Han Qu, Zhaojun Yan, Nan Li, You Wu, Peng Jia

Earth and Planetary Astrophysics

On-sky performance and prospects of near-infrared CMOS detectors in exoplanet detection: first year of SPIRIT

Clàudia Janó-Muñoz, Matthew J. Hooton, Peter P. Pedersen et al. (+8 more)

Ultracool dwarfs are promising targets for detecting and characterising temperate terrestrial exoplanets. Their flux peaks in the near-infrared, beyond the wavelength cut-off of the silicon-based CCDs used by ground-based surveys dedicated to observing them, such as SPECULOOS. We present the on-sky performance of SPIRIT (SPeculoos InfraRed Imager for Transits), an InGaAs CMOS detector on the Callisto telescope at the SPECULOOS Southern Observatory, during its first year of operation, from mid-2022 to 2023. We use 328 visits of 73 targets to optimise our CMOS-specific reduction process, including our approach to glow effects and bad-pixel handling. We find the measured precision to be consistent with our theoretical noise model, achieving sub-part-per-thousand precision under good observing conditions across targets spanning $J$-band magnitudes of 10–13. We further illustrate SPIRIT's capabilities with two case studies: a simultaneous SPIRIT $zYJ$ and CCD $I + z$ observation of a TRAPPIST-1\,h transit, and monitoring observations of the fast-rotating dwarf LP~944-20. Our results confirm that InGaAs infrared CMOS detectors are a cost-effective and competitive technology for ground-based transit photometry of cool stars, and that they show promising prospects to become a core part of the next generation of instruments.
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All authors Clàudia Janó-Muñoz, Matthew J. Hooton, Peter P. Pedersen, Didier Queloz, Khalid Barkaoui, Yasmin T. Davis, Michaël Gillon, Benjamin V. Rackham, Mathilde Timmermans, Amaury H. M. J. Triaud, Sebastián Zúñiga-Fernández

Cosmology and Nongalactic Astrophysics

Low-cost neural summaries for cosmological inference: an ensemble of convolutional neural networks trained on approximate simulations

Iñigo Sáez-Casares, Davide Bianchi, Matteo Calabrese et al. (+1 more)

Machine learning can build near-optimal summary statistics for extracting cosmological information from the large-scale structure of the Universe. Training them, however, requires large numbers of costly simulations. We aim to build a neural summary trained on fast, approximate low-resolution simulations that remains informative when applied to higher-resolution ones, reducing the cost of the training set. We train an ensemble of convolutional neural networks with different architectures to compress the matter overdensity fields of low-resolution particle-mesh simulations. The outputs of a subset of networks are concatenated into a summary statistic, which we use to constrain $\Omega_{\rm m}$ and $\sigma_8$ from high-resolution particle-mesh simulations, each about a thousand times more costly than their low-resolution counterparts. Theoretical predictions are provided by a Gaussian process emulator built from the high-resolution simulations. We test three strategies for selecting the smallest informative subset of networks. Constraints are compared with those from a reference power spectrum analysis. We also consider dark matter halo catalogues from independent high-resolution $N$-body simulations. The neural summary extracts information beyond the binned power spectrum. Using multiple networks is essential: a single network can be less informative than the power spectrum. A greedy search based on posterior volume provides the tightest constraints with the fewest networks. The neural summary also outperforms the power spectrum for dark matter haloes, at different number densities and redshifts, despite being trained on low-resolution matter fields at $z=0$. This work demonstrates that an ensemble of networks trained on approximate simulations yields a summary statistic that remains informative on higher-fidelity data, including dark matter haloes. (Abridged)
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All authors Iñigo Sáez-Casares, Davide Bianchi, Matteo Calabrese, Luigi Guzzo

Astrophysics of Galaxies

PDRs4All XXIII. JWST-MIRI template spectra of PAHs in the Orion Bar obtained with blind signal separation

P. Amiot, O. Berné, J. Roux-Morin et al. (+12 more)

The aromatic infrared bands (AIBs) are observed in a wide variety of astrophysical sources, and now in unprecedented detail by the James Webb space telescope (JWST). These bands are generally attributed to the emission from polycyclic aromatic hydrocarbon (PAHs). Our aim is to extract mid-infrared AIB template spectra from JWST observations of the Orion Bar photo-dissociation region that can be used to derive PAH properties from observations of other objects. We used the JWST MIRI-MRS observations from the PDRs4All program. We first isolated the AIBs from the data using a multi-component fitting approach. We then applied a non-negative matrix factorization to the isolated AIB spectra and extracted two templates, named AIBirrad and AIBshield following previous work. The spatial distribution and spectral characteristics of these two spectra suggest that they originate from two chemical distinct populations. We interpret AIBirrad as emission originating from a PAH population strongly exposed to ultra-violet (UV) radiation and mainly composed of large, compact ionized PAHs. Conversely, AIBshield is interpreted as originating from a more shielded population of PAHs, which is less exposed to the UV by being more embedded in the cloud. This population consists of small, asymmetric and mainly neutral PAHs with bonded aliphatic side groups. These templates can serve to analyze PAH emission in a wide variety of objects observed with MIRI-MRS.
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All authors P. Amiot, O. Berné, J. Roux-Morin, I. Schroetter, C. Boersma, A. Fuente, J. R. Goicoechea, E. Habart, A. Maragkoudakis, T. Onaka, E. Peeters, M. Robberto, A.G.G.M Tielens, D. Van De Putte, S. Vicente

High Energy Astrophysical Phenomena

Black Hole Binary Mergers in Galactic Nuclei: Combined Effects of Secular Dynamics and Stellar Flybys

Hao Wang, Bin Liu and Johan Samsing

Galactic nuclei, with the central supermassive black holes (SMBHs) and surrounding dense star clusters, serve as natural laboratories for studying gravitational dynamics in extreme gravitational environments. In this work, we model the long term evolution of black hole binaries (BHBs) in these environments by incorporating the tidal influence of the central SMBH, the potential of the nuclear star cluster, SMBH induced relativistic precession, and stochastic perturbations from stellar flybys. Our numerical simulations show that the long term evolution of BHBs is predominantly governed by the SMBH-driven ZLK mechanism. However, once stellar flybys are included, they can modify both the binary angular momentum and energy. The cumulative effect of repeated flyby encounters substantially reshapes the long term dynamical evolution, eventually leading systems toward either merger or disruption. Based on a population synthesis study, we find that this combined secular and non-secular channel produces a merger rate of approximately $\mathcal{R}\simeq16\mathrm{Gpc^{-3}yr^{-1}}$, which is significantly higher than the rates predicted by dynamical channels that neglect stellar flybys. Furthermore, we predict that a non-negligible fraction of merging systems would retain detectable eccentricities at low frequencies around 5 Hz, thus providing a distinctive observational signature for next generation ground based GW detectors. Our results demonstrate that the stochastic perturbations from the surrounding environment are essential for modeling BHB evolution in galactic nuclei, and that this channel may contribute a major fraction of observed mergers.
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High Energy Astrophysical Phenomena

Linear Polarization of Synchrotron Radiation from Very-small-pitch-angle Electrons

Meng Nie and Jirong Mao

For synchrotron radiation with pitch angle $\alpha \ll 1/\gamma$ where $\gamma$ is the electron Lorentz factor, referred to as very-small-pitch-angle synchrotron radiation, the polarization properties differ significantly from those of conventional synchrotron radiation ($\alpha \gg 1/\gamma$). In this work, we investigate the linear polarization characteristics of very-small-pitch-angle synchrotron radiation from relativistic thermal and nonthermal electrons. We calculate the linear polarization by applying power-law and Maxwellian electron energy distributions. Moreover, some synchrotron sources exhibit a hybrid distribution of nonthermal and thermal electrons, and we also calculate the polarization degree for a hybrid electron energy distribution. The calculations are performed in the radio, optical, X-ray, and $\gamma$-ray bands. Our results show that the linear polarization degree of very-small-pitch-angle synchrotron radiation is generally lower than that of conventional synchrotron radiation. Very-small-pitch-angle synchrotron radiation from both nonthermal and thermal electrons can produce significant linear polarization. However, the polarization exhibits diverse behaviors across different physical parameters. The general scenario provided in this work can be considered for the application to all kinds of synchrotron sources, as we suggest that the very-small-pitch-angle case is crucial for the study of synchrotron polarization.
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Earth and Planetary Astrophysics

LiDO: The Large inclination Distant Objects Survey

Mike Alexandersen, Rosemary E. Pike, Ying-Tung Chen et al. (+20 more)

Previous trans-Neptunian objects (TNOs) discovery surveys targeted the ecliptic plane, where the overall highest density is seen. High-inclination objects spend little time near the plane, and are thus under-represented in previous TNO surveys. The Large inclination Distant Objects (LiDO) survey targets these high-inclination populations in 34 sq.deg., located in two blocks 14-21 degrees north and south of the ecliptic plane, finding 148 objects, all with i>14 degrees due to survey design. A careful characterization of detection efficiency and other survey parameters results in a "characterized sample" of 125 objects detected within the survey's magnitude and rate limits, thus suitable for model comparison via survey simulations. LiDO detected 62 TNOs classified as resonant, including 21 Plutinos, of which 12 are securely Kozai resonators (always coming to pericenter off-ecliptic), as well as 9 objects in the 5:2 resonance, and several mixed mode inclination-eccentricity resonators. No objects beyond 63 au were detected, despite sensitivity to objects as far as 150 au. We found that the i>14 degree orbital distribution of the previous model from OSSOS was rejectable with the inclusion of the 38 characterized hot classical TNOs from LiDO. We constructed a proof-of-concept orbital distribution model of hot classical TNOs based on long-term stability sculpting, which is statistically acceptable for the LiDO and OSSOS samples, while producing population estimates (21,000$^{+3000}_{-3000}$ hot classicals with H_r<8.3) consistent with OSSOS estimates. The discovery of 125 characterized mid-to-high inclination objects in a variety of orbital classifications provides useful constraints for population modeling and the migration history of the Solar System.
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All authors Mike Alexandersen, Rosemary E. Pike, Ying-Tung Chen, Samantha M. Lawler, Mark Comte, Lowell Peltier, J. J. Kavelaars, Kathryn Volk, Cameron Semenchuck, Cameron Collyer, Jaidyn Draper, Stephen Gwyn, Hermosillo Ruiz, Matthew J. Holman, Katrina Kianpoor, Cameron J. Morgan, Ruth Murray-Clay, Jonathan Pond, Benjamin Proudfoot, AbdulRahman Rabaa, Darin Ragozzine, Emily Rieger, Mriana Yadkoo

Cosmology and Nongalactic Astrophysics

specwizard: A Public Python Framework for Creating Synthetic Absorption Spectra from Hydrodynamical Simulations

Andrés Arámburo-García, Tom Theuns, Joop Schaye et al. (+1 more)

We present specwizard, a publicly available modular Python package for generating synthetic absorption spectra from hydrodynamical simulations. The code combines atomic data from the National Institute of Standards and Technology database with ionisation fractions computed using the cloudy spectral synthesis code for multiple ionising backgrounds, enabling consistent modelling of bound–bound and bound–free absorption for resonant transitions of all ions. specwizard employs a column-density–conserving projection scheme, includes natural line broadening for the Lyman series, and offers optional treatments of instrumental resolution and noise for direct comparison with high-resolution quasar spectra. As example applications of the code, we shoot sightlines through the eagle cosmological simulation to generate a z = 3.2 synthetic quasar spectrum containing H i Lyman-series transitions, including damping wings and Lyman-limit absorption. Additionally, we compute metal-absorption lines probing the circumgalactic medium of simulated galaxies, and investigate the correlated absorption of H i and Si iii. We demonstrate that specwizard applied to outputs from eagle accurately reproduces key observational diagnostics of the Lyman-alpha forest, including the redshift evolution of the mean transmission, the transmission PDF and the transmission power spectrum. We take advantage of the fact that the eagle simulation also reproduces the measured evolution of the temperature-density relation to infer the evolution of the amplitude of the ionizing background, finding excellent agreement with recent theoretical models and measurements.
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All authors Andrés Arámburo-García, Tom Theuns, Joop Schaye, Alexey Boyarsky

Astrophysics of Galaxies

A heterogeneous set of unusual quasars selected from astrometry and broad-band photometry

C. Cheng, K. Valeckas, L. Christensen et al. (+7 more)

The aim of this study is to explore methods for how to identify new quasars with different properties with regard to reddening, redshift, the presence of broad absorption lines from outflows, or other rare properties affecting the broad-band colours. We use Gaia-based astrometric pre-selection to study only sources that have zero parallax and zero proper motion within errors. We subsequently match these sources with information from wide-area photometric surveys and build colour-colour diagrams. Based on these diagrams we select targets for follow-up spectroscopy. In the subsequent analysis we also apply observations from SPHEREx to firmly establish redshifts. We secure spectroscopic observations for 24 sources. Of these, three are found to be stars and the remaining 21 are classified as quasars spanning a redshift range from z=0.139 to z=3.732. The majority of the sources located away from the normal quasar locus in colour-colour diagrams are found to be broad-absorption-line quasars. A single source, the lowest redshift source at z=0.139, is reminiscent of the so-called Little Red Dots found at high redshifts with JWST. Using the simple procedure followed here it is possible to locate previously undiscovered quasars with interesting properties, in particular Broad Absorption Line quasars and quasars with unusual extinction.
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All authors C. Cheng, K. Valeckas, L. Christensen, A. Henderson de la Fuente, L. Fuglsang, V. Vuolteennaho, Pyykkinen, R. H. Rasmussen, S. Bijavara Seshashayana, J. P. U. Fynbo

Astrophysics of Galaxies

Strong gravitational lensing with Euclid

Alessandro Sonnenfeld

Euclid data is going to lead to the discovery of approximately 10^5 new strong gravitational lenses, thereby increasing the number of known lenses by a factor of 30. Such an impressive jump has the potential to revolutionise the field of strong lensing, by covering an ever-increasing range in the parameter space occupied by the lenses and lensed sources, and by uncovering rare and precious strong lens systems. The first quick data release of Euclid has already revealed hundreds of lenses, giving us a taste of what the final Euclid strong lens sample might look like. These lenses include a variety of objects acting as deflectors, from isolated galaxies to clusters, from early-type galaxies to edge-on disks. As many as four double-source plane lenses, in which one foreground object lenses two galaxies at two different redshifts, have already been discovered. As more data are acquired, it might become possible to detect the strong lensing signature of dwarf galaxy satellites, and to find lenses with an unusually large number of images. In this paper, we try to anticipate the kind of discoveries that these data will bring along.
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Astrophysics of Galaxies

Large dust grains escaping from a supernova remnant

Evgenii O. Vasiliev

Dust grains produced in the supernova (SN) ejecta at early ages are partially destroyed in hot gas of the SN remnant. Large grains owing to their inertia can overtake the forward shock front of the remnant and move through the ambient interstellar medium. Using one-dimensional gas dynamics including the dust destruction we study the transport of dust grains inside the SN remnant and the ambient medium. Here we estimate the surviving and escaping mass fractions depending on the cut-off (maximum) size in a power-law distribution of grain sizes. We found that these fractions follow closely each other at late age of the SN remnant, i.e. almost all grains, which have survived in the remnant, leave it for the ambient interstellar medium. At the age of 30 kyr – the onset of the radiative phase with density $n\sim 1$ cm$^{-3}$ with solar metallicity – the escaping/surviving mass fractions for the cut-off size of several microns reach about $0.7-0.8$. The major part of these grains have size larger than $1~\mu$m and initially located at distances $\gtrsim 0.2$ of the ejecta core radius. Later dust grains at velocity of several hundreds km/s escaping the remnant continue to be destroyed due to kinetic sputtering in the interstellar medium. Grains with sizes of several microns are destroyed marginally and therefore will survive in the interstellar gas. After decelerating of grains in the medium the surviving mass fraction of grains produced in the SN remnant, which evolves in an ambient gas with $n$ from 1 to 100 cm$^{-3}$, is from $\sim 0.5$ to $\sim 0.3$, respectively, for the cut-off grain size $a_{cut} = 10~\mu$m. A decrease of the cut-off size in the distribution results in lower surviving mass fraction.
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Instrumentation and Methods for Astrophysics

Identifying Planetary Nebulae Candidates from IPHAS and VPHAS+ Surveys via YOLO Deep Learning Models

Titouan Sérandour, Anne-Laure Méalier, Bruno Colicchio et al. (+5 more)

We present a deep learning detection method capable of effectively identifying planetary nebulae (PNe) on IPHAS and VPHAS+ surveys. Our detection pipeline is based on the YOLO architecture and is adaptable to other datasets. Using the HiPS system, we preprocess and augment the $r$, $i$, and $H{\alpha}$ bands to produce two red, green, and blue (RGB) image datasets: (1) $640 \times 640$ px images at full resolution, and (2) $1 280 \times 1 280$ px images designed to capture extended objects up to $0.2$ deg. Images of $\sim 2600$ PNe are labelled using the HASH database. The loss function and evaluation metrics are adapted to the diffuse and low-contrast nature of PNe; a very low intersection over union (IoU) threshold ($1\%$) is used. A $k$-fold cross validation shows that the YOLOv12m model achieves an average precision of $0.979$ on the first dataset. At a confidence threshold of $0.15$, it achieves a precision rate of $98.7\%$ and a recall rate of $97.4\%$. We deployed our system (on $1280 \times 1280$ images) on the full surveys' coverage ($\sim 3755$ deg$^2$), and present a preliminary analysis of the detection results. The system is robust against artifacts such as CCD corner defects and HiPS tile joints. Our convolutional-neural-network-based model achieved excellent results on the test set, comparable to-or exceeding-that of a recent Swin Transformer approach. However, a challenge persists when applying deep learning models to extensive and densely populated Galactic fields: the development of an automated system that can effectively discriminate PNe from mimics that human experts are able to distinguish (e.g., H II regions). We outline possible improvements for future work.
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All authors Titouan Sérandour, Anne-Laure Méalier, Bruno Colicchio, Dominique Daniel, Philippe Gilberton, Philippe Oros, Thomas Boch, Djaffar Ould Abdeslam