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Physics Astrophysics

astro-ph Watch Astrophysics

Wednesday 24 June

Instrumentation and Methods for Astrophysics

Nautilus Space Observatory: The Evolution of Planets and their Atmospheres

Ilaria Pascucci, Noah Tuchow, Yifan Zhou et al. (+11 more)

We are just beginning to explore the billion-year evolution from nascent planets in disks to mature planetary systems. Recent discoveries hint at demographic and atmospheric differences between young planets and their Gyr-old counterparts, but current facilities are limited - particularly in their ability to conduct statistical atmospheric studies over a broad period range. This white paper outlines compelling science achievable with the Nautilus Space Observatory, a proposed constellation of large-diameter space telescopes. We identify four primary scientific objectives: (1) determining the timescales over which planets evolve into sub-Neptunes and super-Earths; (2) tracking the temporal evolution of atmospheric mass-loss rates; (3) characterizing the evolution of the atmospheric mean molecular weight and C/O ratio; and (4) identifying the emergence of Helium-dominated worlds. Answering these questions requires the high spatial resolution, broad-wavelength coverage, large effective area, and parallelized multiple units that Nautilus provides. By isolating the physical processes that govern the evolution of planets and their atmospheres, these science objectives directly support NASA's Cosmic Origins and Exoplanet Exploration Programs.
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All authors Ilaria Pascucci, Noah Tuchow, Yifan Zhou, Daniel Apai, Chaucer Langbert, Ana Glidden, Luis Welbanks, Chia-Lung Lin, Adina D. Feinstein, Benjamin V. Rackham, Peter Plavchan, Kevin Wagner, Raymond Pierrehumbert, Robin Wordsworth

Instrumentation and Methods for Astrophysics

Fast Simultaneous Surveys with On-the-Fly Mapping

Suman Chatterjee, Sarvesh Mangla, Sourabh Paul et al. (+10 more)

The SKAO is a next-generation radio telescope that will transform our understanding of the formation and evolution of radio galaxies, quasars, transients, and other cosmic sources. Surveys conducted on precursor telescopes can inform us about the capabilities and challenges to be overcome in preparation for SKAO science. The MeerKAT Large Area Synoptic Survey (MeerKLASS), is a pathfinder large area survey to probe cosmology using the single-dish ${\rm H\hspace{0.5mm}}{\scriptsize {\rm I}}$~intensity mapping (IM). MeerKLASS provides an additional wide, high angular-resolution commensal survey by utilizing the “On-the-Fly” (OTF) imaging technique. The survey target is to cover 10,000 sq. degrees in the Southern sky avoiding the Galactic plane, using the UHF-band (544-1088 MHz). The survey aims to achieve an r.m.s. of 25 $\mu$Jy/beam and $14''$ resolution. In this chapter we discuss the survey strategy, observational status, the development of the MeerKLASS OTF imaging pipeline and the science prospects of the data products. OTF imaging, which relies upon constant elevation fast scanning, comes with its own set of challenges, such as smearing. Here we detail how we have mitigated them and the current scientific impact. Significantly fast survey speed ($\sim 3.5$ sq. deg per min), commensality with ${\rm H\hspace{0.5mm}}{\scriptsize {\rm I}}$~IM survey, deep and large area continuum images make MeerKLASS OTF an economic survey technique. Lessons from this technique will be valuable for the upcoming SKA-Mid, where we expect a better resolution $(< 2'')$ and sensitivity $(\sim 7\mu {\rm Jy/beam})$ of the OTF images with the AA4 configuration. Furthermore, improvements in the correlator will result in negligible smearing effects in the imaging.
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All authors Suman Chatterjee, Sarvesh Mangla, Sourabh Paul, Keith Grainge, Matthias Hoeft, Tamera Kassie, Joseph J. Mohr, Yvette Perrott, Kristof Rozgonyi, Mario G. Santos, Oleg M. Smirnov, Cyril Tasse, Laura Wolz

Earth and Planetary Astrophysics

Measuring Asteroid Rotation Periods Using the KMTNet Bulge Survey Data

Haitao Huang, Hongjing Yang, Chung-Uk Lee et al. (+6 more)

Since 2015, the Korea Microlensing Telescope Network (KMTNet) has conducted high-cadence, near-continuous observations of the Galactic bulge for nearly nine months each year from three sites in Chile, South Africa, and Australia, and its wide field of view provides a unique opportunity to extract asteroid lightcurves from archival survey data. In this work, we performed photometric measurements of bright asteroids ($V< 20$~mag) identified within a one-square-degree field during the 2018 KMTNet bulge season. We derived reliable rotation periods for 96 asteroids, including 84 objects without previously published lightcurves. The reliable spin-rates of the asteroids in our sample are broadly consistent with those reported in the Asteroid Lightcurve Database. This archival mining approach can be readily extended to a much larger KMTNet footprint, and the existing $\sim12$~deg$^2$ high-cadence KMTNet dataset has the potential to yield reliable rotation periods (U $\geq 2+$) for more than 5,500 asteroids, substantially expanding the current database of asteroid rotational properties.
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All authors Haitao Huang, Hongjing Yang, Chung-Uk Lee, Qiyue Qian, Jun Tian, Tianjun Gan, Shude Mao, Weicheng Zang, Dong-Jin Kim

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

Electrically Charged Distorted Black Holes: Thermodynamics, Particle Dynamics, and Quasinormal Signatures

Gamal G.L. Nashed and Salvatore Capozziello

We construct an exact solution for the electrically charged extension of a distorted black hole spacetime within Einstein-Maxwell theory using the Harrison transformation. The resulting solution represents a charged deformation of a static distorted vacuum geometry in which the electromagnetic field is introduced through a nonlinear transformation preserving the radial structure of the seed spacetime. Consequently, the Killing horizon remains determined solely by the seed metric and it is not shifted by the electric charge. We analyze the thermodynamic properties of the solution and show that the horizon area, entropy, and temperature are governed by the geometric sector, while the electric charge enlarges the thermodynamic phase space through the electromagnetic potential. The motion of charged test particles is studied using the effective potential formalism, where the distortion parameter modifies circular orbits and shifts the location of the innermost stable circular orbit. We also investigate the black hole shadow for a static observer at finite distance and show that the distortion parameter displaces the photon sphere outward, increasing the apparent shadow size. A geometric correspondence between the photon orbit, determining the shadow and the leading eikonal quasinormal-mode frequency, is discussed, linking optical and perturbative observables. Finally, we study charged scalar perturbations and show that the vanishing horizon electric potential prevents a charged superradiant amplification. In the weak-coupling regime, the quasinormal-mode spectrum is estimated using the WKB method, where the electromagnetic interaction enters through the gauge-invariant combination $(\omega - q_s \xi_t)$ and shifts the oscillation frequencies of the perturbations.
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High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Images of Braneworld black holes with radiatively inefficient accretion flows

Chengjia Chen, Yin Hao, Zelin Zhang et al. (+2 more)

Horizon-scale imaging acts as a transformative tool for probing spacetime geometry, enabling stringent tests of gravitational theories in the strong-field regime. The Casadio-Fabbri-Mazzacurati(CFM) black hole in braneworld contains an extra parameter that characterizes the tidal effects from the bulk geometry, making it highly valuable for this task. We perform general relativistic radiative transfer (GRRT) simulations and generate synthetic images consistent with Event Horizon Telescope observations of M87*. We find that the tidal parameter imprints nonmonotonic changes on the image morphology, underscoring the intricate coupling between spacetime geometry and the observable radiation from the accreting plasma. We also analyze the image-comparison metric using normalized cross-correlation coefficients and the DSSIM index and find that the magnitudes of these mismatches are on the order of 10^3, which implies that identifying braneworld black holes through black hole images remains challenging even with future ngEHT and BHEX observations.
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All authors Chengjia Chen, Yin Hao, Zelin Zhang, Qiyuan Pan, Jiliang Jing

Astrophysics of Galaxies

A Population of Little Red Dot-like Quasars in SDSS

Quinn O. Casey, Ryan C. Hickox, Nikko J. Cleri et al. (+6 more)

Compact and red sources in the high redshift ($z\sim5$) Universe, known as "Little Red Dots" (LRDs), are among JWST's most intriguing discoveries. These sources have broad Balmer emission lines, weak X-ray emission, and unique spectral energy distributions (SEDs) poorly fit by either stellar or AGN templates. Local LRD-like objects allow for detailed studies of the underlying physical processes with archival multi-wavelength datasets unavailable in the high-$z$ Universe. We show that the SDSS $ugriz$ filters at $z\approx0.4, 0.8$ overlap well with the JWST filters used to select LRDs at $z\sim5$. We use SDSS quasars to define a sample of $\sim1300$ Local Red Dots (LoRDs) which share the same photometric colors of LRDs. A subset of the LoRD sample selected to have V-shaped continua ($N=244$) show prominent higher-order Balmer absorption features and [NeV]$\lambda$3426 emission, both of which would likely be missed in JWST/PRISM observations given the low spectral resolution. A composite SED of the LoRDs differs from a typical quasar SED in the rest-frame UV/optical, but the two agree with each other in the NIR. The LoRD SED matches well with a stack of LRDs and can be modeled either as a reddened AGN combined with a host galaxy, or as a reddened AGN combined with a host galaxy and a cool blackbody. Interestingly, the LoRDs are X-ray detected at a rate comparable to typical quasars. However, the probability that LoRDs and typical quasars would go undetected, if subject to the LRD X-ray upper limits, is $>50\%$.
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All authors Quinn O. Casey, Ryan C. Hickox, Nikko J. Cleri, Jonathan H. Cohn, David M. Alexander, Emmanuel Durodola, Kelly E. Whalen, Raphael E. Hviding, Tonima Tasnim Ananna

Earth and Planetary Astrophysics

Glossy Silicate Clouds on the Scorched Dayside of LTT9779b

Suman Saha, James S. Jenkins, Jonathan Brande et al. (+10 more)

Discovered deep within the "Neptunian desert", LTT9779b remains the only known ultra-hot Neptune, prompting significant speculation regarding its unique formation and evolutionary history. Its exceptionally high geometric albedo has previously been attributed either to the presence of clouds or to an extremely metal-rich atmosphere. Here, we present a comprehensive panchromatic analysis of its dayside atmosphere using JWST NIRISS and NIRSpec/G395H observations to characterize its atmospheric structure and composition. Leveraging the exceptional signal-to-noise ratio (S/N) in the observed spectra, we report a 3-to-5$\sigma$ detection of dayside clouds, with strong evidence for Mg$_2$SiO$_4$(s) (silicate) condensation. This constitutes the first statistically significant detection of clouds on the dayside of a Neptunian-mass exoplanet. We demonstrate that a highly reflective cloud deck, rather than an extremely high-metallicity atmosphere, is the most likely explanation for the planet's anomalously high optical albedo. Furthermore, our atmospheric retrievals yield robust detections of both CO ($\sim$4.88$\sigma$) and CO$_2$ ($\sim$8.76$\sigma$), while providing tentative constraints on the H$_2$O abundance and upper limits on SiO, TiO, and VO. Finally, our analysis places a robust constraint on the C/O ratio of 0.984 $\pm$ 0.019. This aligns LTT9779b with other known ultra-hot Jupiters exhibiting super-solar C/O ratios, suggesting a broader trend driven by the sequestration of oxygen-bearing condensates in ultra-hot atmospheres.
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All authors Suman Saha, James S. Jenkins, Jonathan Brande, Reza Ashtari, Ian J. M. Crossfield, Sarah Stamer, Diana Dragomir, Kevin B. Stevenson, Vivien Parmentier, Thomas M. Evans-Soma, Tansu Daylan, Hayley Beltz, Emma Esparza-Borges

Instrumentation and Methods for Astrophysics

Observations of the Cosmic Dawn and Epoch of Reionization with the SKAO: Observational Lessons Learned from Precursors and Pathfinder Instruments

Eloy de Lera Acedo, James Aguirre, Dominic Anstey et al. (+34 more)

This chapter summarizes the observational lessons learned after two decades of observations of the Cosmic Dawn (CD) and Epoch of Reionization (EoR) with SKAO pathfinders and precursors. We will describe the effort towards building accurate simulation pipelines for actual observations and summarize the approaches that different groups have taken to calibrate and mitigate systematic effects such as sky model incompleteness, limited instrument models and antenna mutual coupling. We conclude by discussing the impact that these lessons may have on the design and analysis of upcoming SKAO observations of the Cosmic Dawn and Epoch of Reionization.
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All authors Eloy de Lera Acedo, James Aguirre, Dominic Anstey, Nichole Barry, Gianni Bernardi, Somnath Bharadwaj, Anthony Brown, Jean Cavillot, Suman Chatterjee, Samir Choudhuri, Tyler Cox, John Cumner, Abhirup Datta, Fred Dulwich, Khandakar Md Asif Elahi, Andrew Faulkner, Sukhdeep Singh Gill, Quentin Gueuning, Daniel C. Jacobs, Nicholas Kern, Piyanat Kittiwisit, Yuchen Liu, Zachary Martinot, Ashish Mhaske, Florent Mertens, Vincent McKay, Satyapan Munshi, Steven Murray, Chuneeta D. Nunhokee, Oscar Sage David O'Hara, Samit K. Pal, Robert Pascua, Rashmi Sagar, Shouvik Sarkar, Shiv Sethi, Sarod Yatawatta, Oskar Zetterstrom

Astrophysics of Galaxies

Jets and Outflows in Young Stellar Objects with the SKAO

Giovanni Sabatini, Gemma Busquet, Carlos Carrasco-González et al. (+48 more)

Jets and outflows are ubiquitous phenomena associated with the formation of young stellar objects (YSOs). They play a crucial role in removing angular momentum from the accreting system and in regulating star-formation efficiency. Theoretical studies and observations with ALMA and VLA have shown that jets and winds may have a crucial role in promoting dust growth in the envelope-disc system and in shaping the physical and chemical properties of the surrounding environment. Despite these significant advances, many fundamental questions remain unanswered regarding the acceleration, collimation, and chemical impact of jets and outflows from YSOs. The SKA-project will overcome the limitations of current mm/cm-facilities by enabling high-angular resolution and high-sensitivity cm-observations, crucial for probing jets/outflows near YSOs. Radio recombination lines, combined with proper motions, offer a unique opportunity to study the 3D-kinematics of jets. Non-thermal linearly polarised synchrotron emission will allow measuring magnetic field strength and morphology at unprecedented scales of a few au. Observations of dust emission in outflow cavities will allow studying how dust grows and is eventually transported from the disc to the envelope and back. Finally, the SKA-project will allow exploring the dust composition and chemical enrichment in shocks, where sputtering/shattering of grains cause the release of their mantles and refractory cores in the gas-phase. Complementary to ALMA's detection of simple and complex organic molecules, the SKAO will probe, for the first time, long carbon chains/rings, several Cl-, Al-, Mg-, and other metal-bearing species (missed by current sub-mm facilities).
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All authors Giovanni Sabatini, Gemma Busquet, Carlos Carrasco-González, Adriana Rodríguez-Kamenetzky, Codella Claudio, Linda Podio, Antonio Martínez-Henares, Josep Miquel Girart, Marta De Simone, Luca Cacciapuoti, Guillem Anglada, Lukasz Tychoniec, Lisa Giani, Manoj Puravankara, Francesca Bacciotti, Rafael Bachiller, Eleonora Bianchi, Guillermo Blázquez-Calero, Tyler L. Bourke, Stefano Bovino, Paola Caselli, Francesco Cavallaro, Cecilia Ceccarelli, Elena Diaz-Marquez, Stefano Facchini, Antonio Garufi, Greta Guidi, Tomoya Hirota, John D. Ilee, Adriano Ingallinera, Izaskun Jiménez-Serra, Valerio Lattanzi, Chin-Fei Lee, Manuela Lippi, Alessandro Lupi, Liton Majumdar, Mayank Narang, Mayra Osorio, Marco Padovani, Jaime Pineda, Isaac Radley, Basmah Riaz, Luis Felipe Rodríguez, Alvaro Sánchez-Monge, Alberto Sanna, Silvia Spezzano, Leonardo Testi, Claudia Toci, Alessio Traficante, Himanshu Tyagi, Grazia Maria Umana

Earth and Planetary Astrophysics · Cross-listed from physics.geo-ph

Paleomagnetic signatures of core-mantle interactions inferred from top-heavy thermochemical geodynamo simulations

Souvik Naskar, Jonathan E. Mound, Christopher J. Davies et al. (+3 more)

The time-averaged geomagnetic field provides crucial insights into deep Earth dynamics and thermal core-mantle interactions. Paleomagnetic observations and numerical dynamo simulations are equivocal regarding the longitudinal structure of the time-averaged field, though the latter have often considered a generic buoyancy source, which may obscure distinct signatures of thermal and chemical buoyancy that arise near the equator and poles, respectively. In this study, we present a new suite of top-heavy geodynamo simulations, varying the relative strengths of thermal and chemical driving and comparing the resultant magnetic signatures to observational field models spanning centuries to tens of thousands of years. None of the spatially-averaged measures of field morphology and variability we tested could robustly distinguish between different levels of chemical driving or the presence of heterogeneous outer boundary heat flux. On the other hand, observational constraints requiring longitudinal variations in time-averaged inclination anomaly are readily matched by simulations with heterogeneous outer boundary thermal forcing, in contrast to those with homogeneous mantle heat flux. Longitudinal field structures are reduced, but not erased, by elevated chemical driving, which also promotes the formation and deepening of polar minima in the radial magnetic field. Our simulations indicate that both the strong heat flux heterogeneity and chemical driving in Earth's core are likely to result in small but persistent departures from the geocentric axial dipole approximation.
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All authors Souvik Naskar, Jonathan E. Mound, Christopher J. Davies, Hannah F. Rogers, Stephen J. Mason, Andrew T. Clarke

Earth and Planetary Astrophysics

Can giant impacts be directly detected in other star systems?

Pavan Tanna, Simon Lock, Amy Bonsor et al. (+2 more)

Giant impacts, collisions between planet-sized bodies, play an important role in planet and moon formation. As we enter a new era of large-scale surveys, such as Gaia and LSST at the Vera C. Rubin observatory, there is potential to directly observe the remnants produced in such events and gain insights into the process of planet formation. Here, by modelling the emission and cooling of a series of giant impact remnants, we show that giant impacts are detectable as a sudden brightening followed by gradual dimming in the optical and near-infrared. Giant impacts between Earth-composition planets were simulated using the smoothed particle hydrodynamics code {\small SWIFT}, with total colliding masses ranging from 0.2 to 4 $M_{\oplus}$. By constraining the location of the photic surface of the post-impact bodies produced by the simulations, the initial luminosities of post-impact bodies were found to be between $5\times10^{-5}$ and $10^{-1}$ solar luminosities, with luminosity falling roughly exponentially on a timescale between 1 and 2000 days. Based on our results, along with estimates for planet and giant impact occurrence rates, we anticipate that between 0 and 14 terrestrial giant impacts will be observed in the full release of Gaia epoch photometry in DR4, with at least a comparable number found by LSST. Identifying the remnants of multiple giant impacts will offer a powerful constraint on the frequency of giant impacts in the galaxy and hence the role of such collisions in planet formation.
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All authors Pavan Tanna, Simon Lock, Amy Bonsor, Simon Hodgkin, Cathie. J. Clarke

Cosmology and Nongalactic Astrophysics

Cosmology from Synergies Between SKAO Surveys and Gravitational Wave Observations

Tessa Baker, Alberto Colombo, Steven Cunnington et al. (+11 more)

Both radio surveys and gravitational wave observations have the potential to probe unprecedented volumes in the Universe with systematics independent of existing cosmological probes. This gives them the potential, especially in combination, to solve some of the outstanding issues in cosmology. Here we show how the use of radio observations as electromagnetic signals tracing large scale structures can be used to provide information on gravitational wave standard sirens. By providing a way to link luminosity distance to redshift, this combination can constrain the expansion history of the Universe, and provide information on the Hubble constant ($H_0$). We describe the utility of SKA-Mid neutral hydrogen (\hi) intensity maps, \hi\ galaxy redshift surveys, and continuum galaxy surveys compared to and in conjunction with large contemporaneous optical surveys. Such radio tracers provide a unique, large volume and high redshift information for gravitational wave source, capable of probing effectively the expansion history of the Universe $H(z)$.
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All authors Tessa Baker, Alberto Colombo, Steven Cunnington, Ulyana Dupletsa, José Fonseca, Ian Harrison, Konstantin Leyde, Simone Mastrogiovanni, Riccardo Murgia, Dounia Nanadoumgar-Lacroze, Tommaso Ronconi, Giulio Scelfo, Matteo Schulz, Marta Spinelli

Cosmology and Nongalactic Astrophysics

The Cosmic Ray Life Cycle in Galaxy Clusters

Francesco de Gasperin, Marcus Brüggen, Henrik Edler et al. (+3 more)

Within the cosmic web, gravitational energy, linked to the formation and growth of the Universe's largest structures and the activity of active galactic nuclei (AGN), is converted to heat through processes such as turbulence and shock waves. These processes have a fundamental impact on the evolution of galaxy clusters. For example, they lead to the amplification of magnetic fields and the production of cosmic ray (CR) electrons that emit continuum radio waves via synchrotron emission. This produces sources on scales of the entire hosting clusters. These large radio sources in galaxy clusters are often classified based on their morphological appearance as radio halos, cluster radio shocks (radio relics), and other types. To understand the CR acceleration processes in galaxy clusters (and beyond), and to gain a comprehensive view of these sources, including their long-term interactions, SKA telescope should conduct both deep observations of a carefully selected sample of nearby clusters as well as shallower wide-area surveys. Thanks to their capabilities - in particular the sensitivity to polarised and low-frequency emission - SKA-Mid (Bands 1 and 2) and SKA-Low are ideally suited to probing magnetic field structures in galaxy clusters, as well as the large reservoir of low-energy CRs that may be accelerated by yet-unexplored microphysical mechanisms. The high sensitivity to low-frequency emission will also be fundamental to detect the long term actions and interactions of these phenomena over gigayear timescales.
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All authors Francesco de Gasperin, Marcus Brüggen, Henrik Edler, Reinout J. van Weeren, Tiziana Venturi, Gianfranco Brunetti

Cosmology and Nongalactic Astrophysics

Cosmology with Tully-Fisher HI Galaxy Surveys

Joël Mayor, Anthony Carr, Khaled Said et al. (+7 more)

The SKA Observatory will enable measurements of the Tully-Fisher relation for statistical samples of HI selected galaxies out to unprecedented depths and redshifts thanks to its unique combined spatial and spectral sensitivity. This chapter explores the transformative potential of such surveys for cosmology, in particular in the field of peculiar velocity measurements. We briefly review the present observational landscape for Tully-Fisher HI galaxy surveys and existing peculiar velocity datasets, and compare them with predictions for SKAO Tully-Fisher HI galaxy surveys with AA* and AA4 configurations of the SKA-Mid array. We discuss the extended range of cosmology science cases covered and enabled by such surveys.
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All authors Joël Mayor, Anthony Carr, Khaled Said, Gabriella De Lucia, Anastasia Ponomareva, Philip Bull, Stefano Camera, Ainulnabilah Nasirudin, Marta Spinelli, Robert Yates

Astrophysics of Galaxies

The evolution of the galaxy gas-phase mass-metallicity relation from $z=15$ to $z=0$ in the COLIBRE cosmological simulations

Piyush Sharda, Joop Schaye, Robert J. McGibbon et al. (+8 more)

We present the evolution of the galaxy gas-phase mass-metallicity relation (MZR) from $z=15$ to $z=0$ in the COLIBRE cosmological hydrodynamical simulations. Amongst other novel features, COLIBRE follows the multiphase interstellar medium with gas allowed to cool to $\sim 10\,\mathrm{K}$, and includes a new chemistry model in which hydrogen and helium are tracked in non-equilibrium, metals are allowed to mix and diffuse, and the chemical network is coupled to a self-consistent live dust model. Using fiducial COLIBRE runs spanning particle masses from $10^5\,\mathrm{M_{\odot}}$ to $10^7\,\mathrm{M_{\odot}}$ and box sizes $25 - 400\,\mathrm{cMpc}$, we derive the median, mass-weighted MZRs for star-forming galaxies and compare them with a comprehensive compilation of observational data and other simulations. COLIBRE reproduces the observed MZR across cosmic time, notwithstanding the systematic uncertainties in observational measurements of the gas-phase oxygen abundances. The simulations show excellent numerical convergence and uniquely probe the full stellar mass range sampled by current observations across all redshifts. We find that the MZR is already in place at cosmic dawn ($z \approx 10$), and shows no evolution until $z \approx 5$. The slope of the MZR becomes shallower at low redshifts. The turnover at the high-mass end is largely governed by feedback from active galactic nuclei (AGN), whereas the low-mass end of the MZR sensitively depends on the strength of feedback from core collapse supernovae. Variations in the star formation efficiency or depletion of oxygen on dust grains have a more minor impact on the MZR. We identify key physical processes that shape the MZR across cosmic time and highlight where future observations can further constrain galaxy formation models.
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All authors Piyush Sharda, Joop Schaye, Robert J. McGibbon, Alejandro Benítez-Llambay, Evgenii Chaikin, Carlos S. Frenk, Jacqueline Hodge, Filip Huško, Sylvia Ploeckinger, Alexander J. Richings, Matthieu Schaller

Cosmology and Nongalactic Astrophysics

HI Simulations for Cosmology with the SKA Observatory

Tommaso Ronconi, Gabriella De Lucia, Marta Spinelli et al. (+15 more)

We present a comparative overview of state-of-the-art methods for modelling the distribution of neutral hydrogen (HI) in the post-reionization Universe, developed in preparation for upcoming SKAO cosmological surveys. Our aim is to assess how different physical and empirical assumptions reflect into predictions for key observables such as the cosmic HI density, the HI mass function, and the HI-halo mass relation. We consider both: (i) semi-analytical approaches that self-consistently evolve baryonic components within dark matter merger trees through physically motivated prescriptions and (ii) empirical schemes tailored to different observables and based on fast approximations designed for large ensemble studies. By comparing the predictions from the different methods considered, we find overall consistency in integrated quantities such as $\Omega_{\mathrm{HI}}$, yet systematic differences in the detailed shape and scatter of the HI–halo mass relation and its redshift evolution. Semi-analytical models offer physically grounded predictions but depend on assumed prescriptions, while empirical methods provide flexibility and computational efficiency at the expense of robustness in extrapolated regions of the parameter space. The increasing number of HI measurements from SKA precursors and pathfinders (including surveys with MeerKAT, ASKAP, and FAST) will provide critical observational constraints to refine and calibrate current simulation methodologies. In turn, increasingly realistic HI simulations play a key role in interpreting these data, guiding survey design and analysis strategies, in preparation for the advent of SKAO data.
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All authors Tommaso Ronconi, Gabriella De Lucia, Marta Spinelli, Pascal Hitz, Fabio Fontanot, Francesco Sinigaglia, Lizhi Xie, Robert M. Yates, José Luis Bernal, Anna Bonaldi, Stefano Camera, Isabella P. Carucci, Steven Cunnington, Francisco-Shu Kitaura, Joël Mayor, Rajesh Mondal, Giulia Piccirilli, Digvijay Wadekar

Cosmology and Nongalactic Astrophysics

Single-dish HI Intensity Mapping with the SKAO: Precursor Progress with MeerKAT's Large Area Synoptic Survey (MeerKLASS)

Steven Cunnington, Jingying Wang, Mario G. Santos et al. (+16 more)

Using the SKAO to map the intensity of neutral hydrogen's 21cm emission line will be a golden opportunity to constrain models of cosmology. To access the largest cosmological scales, wide-sky surveys should ideally reach thousands of square degrees, requiring SKA-Mid's dishes to scan the sky in auto-correlation mode, so-called single-dish observations. In this chapter, we overview the latest results from MeerKAT's Large Area Synoptic Survey (MeerKLASS), which has been pioneering this single-dish observing strategy, and motivating its continuation with the SKA-Mid AA4 deployment. MeerKLASS, operating on the same Karoo site where the SKA-Mid is being built, has now achieved multiple cosmological detections from single-dish observations, including high-significance cross-correlations with optical galaxy surveys and continually improving measurements of the HI auto-power spectrum. These results demonstrate that stable calibration, effective foreground mitigation, and statistical recovery of cosmological signal are all achievable with a large multi-dish telescope in total-power mode. The success of MeerKLASS therefore validates the observational strategies required for SKA-Mid and marks a key milestone in demonstrating the viability of single-dish HI intensity mapping for cosmology. Looking ahead, SKA-Mid's increased sensitivity and Band 1 coverage (350-1050 MHz) will allow the same methodology to probe redshifts up to $z\,{\sim}\,3$, mapping volumes several orders of magnitude larger than currently accessible. The techniques refined with MeerKLASS thus form the operational and scientific foundation for a large portion of the SKAO's cosmology programme.
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All authors Steven Cunnington, Jingying Wang, Mario G. Santos, Matilde Barberi-Squarotti, Philip Bull, Stefano Camera, Isabella P. Carucci, Zhaoting Chen, Brandon Engelbrecht, José Fonseca, Karin Fornazier, Keith Grainge, Wenkai Hu, Melis O. Irfan, Yichao Li, Alkistis Pourtsidou, Marta Spinelli, Amadeus Witzemann, Laura Wolz

High Energy Astrophysical Phenomena

Using SKA-Low to Detect PeV Gamma-rays from Galactic Sources

Anna Nelles, Philipp Laub, Haoning He et al. (+28 more)

Detecting so called PeVatrons is considered one of the prime goals of $\gamma$-ray astronomy. PeVatrons are astrophysical objects in the Galaxy that are sources of cosmic rays exceeding PeV ($10^{15}$ eV) energies, the highest in our Galaxy. Their nature is unknown as of now, with some candidates reaching barely above PeV energies just having been identified. Serendipitously, the energy threshold of air shower detection using radio emission, has been proven at 50 PeV. There is a case to be made that SKA-Low with its unprecedented number of antennas, can reach lower in energy, while the size of the core is sufficiently large provide a significant effective area to measure PeV fluxes. While this promises a novel angle towards understanding the cosmic ray accelerators in our Galaxy, it also would be the first detection of $\gamma$-ray air showers using radio emission.
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All authors Anna Nelles, Philipp Laub, Haoning He, Felix Schlüter, Sjoerd Bouma, Justin Bray, Stijn Buitink, Arthur Corstanje, Vital De Henau, Edwin Dickinson, Brian Hare, Jörg Hörandel, Tim Huege, Clancy James, Xingyu Li, Hermann-Josef Mathes, Katharine Mulrey, Subhadip Saha, Olaf Scholten, Ralph Spencer, Christopher Sterpka, Karen Terveer, Satyendra Thoudam, Gia Trinh, Paulina Turekova, Darko Veberic, Keito Watanabe, Hiroaki Yamamoto, Chao Zhang, Pengfei Zhang, Yi Zhang

Astrophysics of Galaxies

Spectroscopic surveys with the SKA probing the ionized and molecular Milky Way

A. Karska, J.R. Dawson, A.M. Jacob et al. (+12 more)

Radio spectroscopic surveys provide us with a comprehensive picture of the Milky Way across many physical and chemical regimes. Spectral lines primarily probe the multi-phase gaseous interstellar medium (ISM) from its ionized to atomic and molecular phases, and constrain both local and galaxy-scale kinematics and structure through Doppler shifts. By investigating the physical and chemical properties and distribution of the ISM, the processes driving star formation and galaxy evolution can be studied in detail. This motivates line surveys of our Galaxy that allow us to use the range of physical conditions found in the Milky Way as a template for understanding star formation in extragalactic environments. In this chapter, we describe the science enabled by the spectroscopy of small molecules and radio recombination lines of atoms toward a range of Galactic environments with the SKA. We address questions concerning the processes that dictate the formation of molecular clouds (OH, CH), the properties of warm, ionized gas and the potential of HII regions in understanding the structure of the Galaxy (radio recombination lines), and the impact of CO-dark molecular gas across various density regimes on star formation and galaxy evolution (OH, H2CO). We propose a survey that includes the inner and outer Galaxy disk, characterized by a broad range of densities, temperatures, and metallicities. Deep, wide-field observations of small molecules will be uniquely accessible with SKA, providing key insights on the condition of interstellar medium in galaxies and its impact on star formation.
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All authors A. Karska, J.R. Dawson, A.M. Jacob, T.V. Wenger, J.S. Urquhart, D. Colombo, L.D. Anderson, V.S. Veena, M. Rugel, M.A. Thompson, P.D. Klaassen, H. Beuther, M.P. Busch, A. Traficante, G. Sabatini

High Energy Astrophysical Phenomena

Two years of shock interaction tracing three phases of evolution: the explosion of a Type IIn supernova, SN 2019vxm

Gitika Rameshan, Rishabh Singh Teja, D. K. Sahu et al. (+10 more)

We present multi-wavelength photometric and optical spectroscopic observations of the long-lived interacting supernova SN 2019vxm, spanning more than two years after the explosion. SN 2019vxm is a slowly rising (rise time ~ 45.9 days in the R-band), slowly declining supernova reaching an R-band peak absolute magnitude of ~-20.3 mag. The SN light curve post-maximum shows a shallow decline, followed by a secondary, steeper decline in the optical (0.01 mag/day), with late-time IR brightening. The total radiated luminosity is 5x10^50 erg, placing it among the energetic class of its type. We estimated a CSM mass of 3-8 M_sun through light-curve modeling (independent of the CSM density profile) and by comparison with theoretical models. We estimate a minimum ejecta mass of ~ 3.88 M_sun from the broad H-alpha component, consistent with the ejecta mass obtained from the light curve models. The solely interaction-dominated initial epochs are later accompanied by photon-scattering signatures, leading to asymmetric line profiles with symmetric wings. The late phase, characterized by enhanced brightness at longer wavelengths and a stronger asymmetric line profile with the red side flux strongly suppressed, indicates the influence of pre-existing or newly formed dust with temperatures ~ 1500 K at ~4x10^16 cm. Even in the late phases, no nebular lines are present in the spectra, indicating dense or obscured ejecta.
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All authors Gitika Rameshan, Rishabh Singh Teja, D. K. Sahu, G. C. Anupama, Masayuki Yamanaka, Keiichi Maeda, Tatsuya Nakaoka, Sota Goto, Brajesh Kumar, Avinash Singh, Miho Kawabata, Koji S. Kawabata, Kenta Taguchi

Astrophysics of Galaxies

Cosmic evolution of the helium and oxygen abundances in type 2 Active Galactic Nuclei: Helium-loud AGNs

O. L. Dors, M. Armah, G. F. Hägele et al. (+14 more)

We derive the helium and oxygen abundances in the Narrow Line Regions (NLRs) of 84 Active Galactic Nuclei (AGNs) spanning two redshift ranges: 65 objects at $z \: < \: 0.2$ and 19 objects at $2.8 \lesssim z \lesssim 6.8$. Spectroscopic data in the optical rest-frame range [3000 ${\lambda}(\text{\AA})$ 7000] from the JADES survey and from the literature were used to estimate $\text{He/H}$ and $\text{O/H}$ via the $T_{\rm e}$-method (7 objects) and strong-emission line calibrations (19 objects). Our results indicate that the ionization degree in AGNs increases toward higher redshifts, exhibiting a trend similar to that observed in star-forming galaxies. We find that the majority of our sample of AGNs at $z \: > \: 2.8$ show oversolar helium abundances and subsolar oxygen abundances. We identified, via the $T_{\rm e}$-method, an object (goods-s-mediumhst-58850; $z=6.2615$) with the highest helium abundance estimated to date, i.e. $12+\log({\rm He/H})=11.64$, corresponding to $\rm (He/He_{\odot}) \sim 4.4$. This result remains robust even when we adopt larger electron densities (varying $N_{\rm e}$ from $500$ to $10\:000$ $\rm cm^{-3}$) in abundance estimates using the $T_{\rm e}$-method and empirical strong-line methods. We found marginal evidence for a decline in the He/H abundance ($\sim 0.04$ dex per redshift unit) toward lower redshifts. In contrast, we found evidence for an increase in $\text{O/H}$ toward the local universe at a rate of approximately 0.06 dex per redshift unit.
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All authors O. L. Dors, M. Armah, G. F. Hägele, M. V. Cardaci, P. C. Santos, R. A. Riffel, G. Cresci, R. Riffel, L. N. Marinho, X. Ji, Y. Isobe, R. Maiolino, A. Marconi, A. Feltre, R. L. Sanders, I. N. Morais, G. C. Almeida

Astrophysics of Galaxies

Euclid Quick Data Release (Q2) – The Euclid Galactic Bulge Survey

J.-P. Beaulieu, E. Bachelet, M. Gilles et al. (+173 more)

The Euclid Quick Data Release Q2 provides an unprecedented deep, wide-field, high-angular-resolution view of the inner Galactic bulge through the Euclid Galactic Bulge Survey (EGBS). Nine contiguous fields covering 4.8 deg$^2$ were observed with the VIS instrument over 24 hours in March 2025. Unlike the nominal Euclid survey strategy, the EGBS employed 16 dithered exposures of 400 s each, corresponding to a total integration time of 1.8 hours per field. Dedicated calibration observations were obtained to derive point spread functions (PSFs). The primary objective of the EGBS is gravitational microlensing, with high-angular-resolution imaging enabling lens-mass measurements to better than 10%. The survey provides an optical reference dataset for previously discovered microlensing events and future observations of the Galactic bulge. The Q2 data were processed with the VIS-PF pipeline. The non-standard observing strategy required dedicated calibration products, while the extreme stellar density necessitated modifications to the astrometric calibration and cosmic-ray detection procedures. These improvements have since been incorporated into later pipeline versions. We describe the motivation, observing strategy, data processing, products, and first results of the EGBS. Astrometric residuals with respect to the Gaia DR3 catalogue are 5.5 mas in right ascension and 4.4 mas in declination across the survey area, while the photometric zero points are calibrated to 1.5%. The Q2 release includes calibrated single-dither images, dedicated PSF models, and photometric catalogues containing approximately 45 million detected sources per dither down to AB magnitude 26. Although incomplete because of extreme crowding, these products provide a robust astrometric and photometric foundation for future exploitation of the dataset.
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All authors J.-P. Beaulieu, E. Bachelet, M. Gilles, C. Ranc, E. N. Rektsini, E. Kerins, M. T. Penny, H. Verma, S. Mottet, R. Vavrek, V. Bozza, J.-C. Cuillandre, M. Chang, L. R. Bedin, K. Kuijken, C. Laigle, M. Libralato, I. McDonald, R. Nakajima, V. Popoff, J. Rhodes, E. Thygesen, S. Awan, J. E. Davies, A. M. Di Giorgio, T. Flanet, C. Grenet, O. Herent, P. Hudelot, K. Jahnke, R. Kohley, H. J. McCracken, H. N. Nguyen-Kim, M. Page, M. Schirmer, F. Soldano, B. Altieri, S. Andreon, N. Auricchio, H. Aussel, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, R. Bender, A. Biviano, M. Brescia, S. Camera, V. Capobianco, C. Carbone, V. F. Cardone, J. Carretero, M. Castellano, G. Castignani, S. Cavuoti, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Cropper, H. Degaudenzi, G. De Lucia, C. Dolding, H. Dole, F. Dubath, X. Dupac, S. Dusini, S. Escoffier, M. Farina, R. Farinelli, F. Faustini, S. Ferriol, F. Finelli, S. Fotopoulou, N. Fourmanoit, M. Frailis, L. Gabarra, S. Galeotta, W. Gillard, B. Gillis, C. Giocoli, P. Gómez-Alvarez, A. Grazian, F. Grupp, L. Guzzo, W. G. Hartley, S. V. H. Haugan, G. Helou, S. Hemmati, H. Hoekstra, W. Holmes, I. M. Hook, F. Hormuth, A. Hornstrup, M. Jhabvala, B. Joachimi, S. Kermiche, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, R. Laureijs, A. M. C. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, M. Magliocchetti, G. Mainetti, O. Mansutti, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, E. Medinaceli, M. Melchior, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, C. Moretti, L. Moscardini, C. Neissner, S.-M. Niemi, J. W. Nightingale, C. Padilla, S. Paltani, F. Pasian, W. J. Percival, V. Pettorino, G. Polenta, M. Poncet, G. D. Racca, F. Raison, A. Renzi, G. Riccio, I. Risso, F. Rizzo, E. Romelli, M. Roncarelli, B. Rusholme, R. Saglia, Z. Sakr, A. G. Sánchez, D. Sapone, P. Schneider, T. Schrabback, A. Secroun, E. Sihvola, P. Simon, C. Sirignano, G. Sirri, J. Skottfelt, L. Stanco, P. Tallada-Crespí, A. N. Taylor, I. Tereno, S. Toft, R. Toledo-Moreo, F. Torradeflot, A. Tsyganov, I. Tutusaus, J. Valiviita, T. Vassallo, Y. Wang, J. Weller, A. Zacchei, F. M. Zerbi, E. Zucca, M. Sereno

High Energy Astrophysical Phenomena

Broadband multiwavelength properties of the archetypal blazar 3C 279 during the 2017 Event Horizon Telescope campaign

G. Principe, J. C. Algaba, E. Aviano et al. (+530 more)

The archetypal blazar 3C 279 hosts a prominent relativistic jet and exhibits strong broadband variability across the electromagnetic spectrum. In April 2017, the Event Horizon Telescope (EHT) observed 3C 279, alongside one of the most extensive quasi-simultaneous multiwavelength (MWL) campaigns ever conducted. With the aim of investigating the physical processes governing 3C 279, we analyzed individual observations and multiband light curves, and constructed a new quasi-simultaneous MWL spectrum. We also performed phenomenological modeling using the turbulent extreme multi-zone (TEMZ) model to constrain the fundamental physical properties of the source. The EHT observations reveal a clear flux increase in the innermost core between April 5 and 11, 2017. Over a broader timescale, radio measurements at longer wavelengths show concurrent enhancements in core flux and polarization around mid-April, coinciding with the ejection of a superluminal knot. Record UV-optical flares with strong polarization variability occurred in late March, followed by gamma-ray activity that declined before the end of the EHT observing period. During this interval, the source remained in a low X-ray state and showed no detectable VHE emission. The TEMZ modeling suggests that the broadband spectrum and variability of 3C 279 can be explained within a jet scenario in which turbulent plasma cells are compressed by a stationary conical shock. However, alternative interpretations, such as magnetic reconnection or a moving shock-in-jet event, remain plausible. This coordinated MWL campaign advances our understanding of the origin of jet and gamma-ray emission in 3C 279, while also providing a comprehensive publicly available dataset that will serve as a valuable reference for future studies.
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All authors G. Principe, J. C. Algaba, E. Aviano, W.Y. Cheong, K. Hada, D. Haggard, A. Hahn, S.G. Jorstad, E. V. Kravchenko, Y. Kovalev, S.S. Lee, M. Lisakov, S. Markoff, A.P. Marscher, M. Sasada, P. Voitsik, Kazunori Akiyama, Ezequiel Albentosa-Ruiz, Antxon Alberdi, Walter Alef, Richard Anantua, Eleni Antonopoulou, Keiichi Asada, Rebecca Azulay, Anne-Kathrin Baczko, David Ball, Bidisha Bandyopadhyay, John Barrett, Michi Baubock, Bradford A. Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Katherine L. Bouman, Geoffrey C. Bower, Michael Bremer, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Douglas F. Carlos, John E. Carlstrom, Andrew Chael, Chi-kwan Chan, Dominic O. Chang, Koushik Chatterjee, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Paul Chichura, Ilje Cho, Nicholas S. Conroy, John E. Conway, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Brandon Curd, Rohan Dahale, Jordy Davelaar, Joost de Kleuver, Mariafelicia De Laurentis, Roger Deane, Jason Dexter, Vedant Dhruv, Indu K. Dihingia, Sheperd S. Doeleman, Sergio A. Dzib, Razieh Emami, Heino Falcke, Joseph Farah, Vincent L. Fish, Edward Fomalont, H. Alyson Ford, Marianna Foschi, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Charles F. Gammie, Roberto Garcia, Olivier Gentaz, Boris Georgiev, Ciriaco Goddi, Roman Gold, Arturo I. Gomez-Ruiz, Jose L. Gomez, Minfeng Gu, Mark Gurwell, Ronald Hesper, Dirk Heumann, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang, David H. Hughes, Shiro Ikeda, C. M. Violette Impellizzeri, Makoto Inoue, Sara Issaoun, David J. James, Buell T. Jannuzi, Michael Janssen, Britton Jeter, Wu Jiang, Alejandra Jimenez-Rosales, Michael D. Johnson, Adam C. Jones, Abhishek V. Joshi, Taehyun Jung, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Dong-Jin Kim, Jae-Young Kim, Jongsoo Kim, Junhan Kim, Motoki Kino, Jakob Knollmüller, Jun Yi Koay, Prashant Kocherlakota, Yutaro Kofuji, Patrick M. Koch, Shoko Koyama, Carsten Kramer, Joana A. Kramer, Michael Kramer, Thomas P. Krichbaum, Cheng-Yu Kuo, Noemi La Bella, Deokhyeong Lee, Aviad Levis, Shaoliang Li, Zhiyuan Li, Rocco Lico, Greg Lindahl, Michael Lindqvist, Jun Liu, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, Andrei P. Lobanov, Laurent Loinard, Colin J. Lonsdale, Amy E. Lowitz, Ru-Sen Lu, Nicholas R. MacDonald, Jirong Mao, Nicola Marchili, Daniel P. Marrone, Alan P. Marscher, Ivan Marti-Vidal, Satoki Matsushita, Lynn D. Matthews, Lia Medeiros, Karl M. Menten, Hugo Messias, Izumi Mizuno, Yosuke Mizuno, Joshua Montgomery, Kotaro Moriyama, Monika Moscibrodzka, Wanga Mulaudzi, Cornelia Müller, Hendrik Müller, Alejandro Mus, Gibwa Musoke, Ioannis Myserlis, Hiroshi Nagai, Neil M. Nagar, Dhanya G. Nair, Masanori Nakamura, Gopal Narayanan, Iniyan Natarajan, Antonios Nathanail, Santiago Navarro Fuentes, Joey Neilsen, Chunchong Ni, Andy Nilipour, Michael A. Nowak, Hiroki Okino, Hector Ra.l Olivares Sanchez, Feryal Ozel, Daniel C. M. Palumbo, Georgios Filippos Paraschos, Jongho Park, Harriet Parsons, Nimesh Patel, Ue-Li Pen, Dominic W. Pesce, Vincent Pietu, Alexander Plavin, Aleksandar PopStefanija, Oliver Porth, Ben Prather, Dimitrios Psaltis, Hung-Yi Pu, Alexandra Rahlin, Venkatessh Ramakrishnan, Ramprasad Rao, Mark G. Rawlings, Angelo Ricarte, Luca Ricci, Bart Ripperda, Jan Roder, Freek Roelofs, Cristina Romero-Ca.izales, Eduardo Ros, Arash Roshanineshat, Helge Rottmann, Alan L. Roy, Ignacio Ruiz, Chet Ruszczyk, Kazi L. J. Rygl, Leon D. S. Salas, Salvador Sanchez, David Sanchez-Argüelles, Miguel Sanchez-Portal, Ali SaraerToosi, Kaushik Satapathy, Saurabh, Tuomas Savolainen, Karl-Friedrich Schuster, Zhiqiang Shen, Sasikumar Silpa, Randall Smith, Bong Won Sohn, Jason SooHoo, Kamal Souccar, Joshua S. Stanway, He Sun, Alexandra J. Tetarenko, Paul Tiede, Remo P. J. Tilanus, Michael Titus, Kenji Toma, Pablo Torne, Teresa Toscano, Efthalia Traianou, Sascha Trippe, Matthew Turk, Ilse van Bemmel, Bram van den Berg, Huib Jan van Langevelde, Daniel R. van Rossum, Sebastiano D. von Fellenberg, Jesse Vos, Jan Wagner, Zhiren Wang, Derek Ward-Thompson, John Wardle, Jasmin E. Washington, Jonathan Weintroub, Maciek Wielgus, Kaj Wiik, Michael F. Wondrak, George N. Wong, Jompoj Wongphexhauxsorn, Qingwen Wu, Paul Yamaguchi, Aristomenis Yfantis, Doosoo Yoon, Andre Young, Ziri Younsi, Wei Yu, Feng Yuan, Ye-Fei Yuan, Ai-Ling Zeng, J. Anton Zensus, Shuo Zhang, Guang-Yao Zhao, J. Abhir, A. Abhishek, V. A. Acciari, A. Aguasca-Cabot, I. Agudo, I. Albanese, T. Aniello, S. Ansoldi, L. A. Antonelli, A. Arbet Engels, C. Arcaro, T. T. H. Arnesen, A. Babic, C. Bakshi, U. Barres de Almeida, J. A. Barrio, L. Barrios-Jimenez, I. Batkovic, J. Becerra Gonz.lez, W. Bednarek, E. Bernardini, J. Bernete, A. Berti, J. Besenrieder, C. Bigongiari, A. Biland, O. Blanch, G. Bonnoli, Ž. Bošnjak, E. Bronzini, I. Burelli, A. Campoy-Ordaz, A. Carosi, R. Carosi, M. Carretero-Castrillo, A. J. Castro-Tirado, D. Cerasole, G. Ceribella, A. Cervi.o, Y. Chai, G. Chon, J. L. Contreras, J. Cortina, S. Covino, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, M. Delfino, J. Delgado, C. Delgado Mendez, F. Di Pierro, R. Di Tria, L. Di Venere, A. Dinesh, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, L. Eisenberger, D. Elsaesser, L. Foffano, L. Font, F. Fr.as Garcia-Lago, S. Fr.se, Y. Fukazawa, S. Gasparyan, M. Gaug, J. G. Giesbrecht Paiva, N. Giglietto, F. Giordano, P. Gliwny, T. Gradetzke, R. Grau, J. G. Green, P. Günther, D. Hadasch, G. Harutyunyan, J. Herrera Llorente, D. Hrupec, D. Israyelyan, J. Jahanvi, I. Jimenez Martinez, J. Jimenez Quiles, S. Kankkunen, T. Kayanoki, J. Konrad, P. M. Kouch, H. Kubo, J. Kushida, M. L.inez, A. Lamastra, E. Lindfors, S. Lombardi, F. Longo, R. Lopez-Coto, M. Lopez-Moya, A. Lopez-Oramas, S. Loporchio, L. LuliLc, P. Majumdar, M. Makariev, M. Mallamaci, G. Maneva, M. Manganaro, S. Mangano, K. Mannheim, S. Marchesi, M. Mariotti, M. Martinez, P. Maruševec, D. Mazin, S. Menchiari, J. M.ndez Gallego, S. Menon, D. Miceli, J. M. Miranda, R. Mirzoyan, M. Molero Gonzalez, E. Molina, H. A. Mondal, A. Moralejo, C. Nanci, A. Negro, V. Neustroev, C. Nigro, L. Nikolic, K. Noda, S. Nozaki, A. Okumura, J. Otero-Santos, S. Paiano, D. Paneque, R. Paoletti, J. M. Paredes, M. Peresano, M. Persic, M. Pihet, G. Pirola, F. Podobnik, P. G. Prada Moroni, E. Prandini, M. Rib., J. Rico, A. Roy, N. Sahakyan, F. G. Saturni, F. Schiavone, K. Schmitz, A. Sciaccaluga, G. Silvestri, A. Simongini, J. Sitarek, V. Sliusar, D. Sobczynska, A. Stamerra, J. Striškovic, D. Strom, Y. Suda, M. Takahashi, R. Takeishi, J. Tartera Barber., P. Temnikov, T. Terzic, M. Teshima, A. Tutone, S. Ubach, S. Ventura, G. Verna, I. Viale, A. Vigliano, C. F. Vigorito, E. Visentin, V. Vitale, M. Vorbrugg, I. Vovk, R. Walter, C. Walther, F. Wersig, P. K. H. Yeung, A. Acharyya, F. Aharonian, H. Ashkar, M. Backes, M. Barnard, Y. Becherini, M. B.ttcher, J. Bolmont, B. Bruno, T. Bylund, S. Casanova, M. Chernyakova, J. O. Chibueze, O. Chibueze, B. Cornejo, J. Damascene Mbarubucyeye, I.D. Davids, J. de Assis Scarpin, M. de Naurois, A. Dmytriiev, K. Egberts, S. Fegan, K. Feijen, M. D. Filipovic, G. Fontaine, S. Gabici, J.F. Glicenstein, P. Goswami, L. Heckmann, B. He., M. Holler, D. Horns, E. Kasai, K. Katarzynski, D. Kerszberg, B. Kh.lifi, K. Kosack, R.G. Lang, S. Lazarevic, P. Liniewicz, A. Luashvili, D. Malyshev, D. Malyshev, M. G. F. Mayer, M. Meyer, A. Mikhno, E. Moulin, H. Ndiyavala, J. Niemiec, P. Pichard, T. Preis, G. Pühlhofer, A. Quirrenbach, A. Reimer, O. Reimer, I. Reis, B. Rudak, K. Sabri, V. Sahakian, A. Santangelo, M. Sasaki, I. Shebalkova, W. Si Said, L. Stawarz, R. Steenkamp, T. Tanaka, G. L. Taylor, R. Terrier, Y. Tian, M. Tluczykont, C. Venter, J. Vink, V. Voitsekhovskyi, S.J. Wagner, A. Wierzcholska, M. Zacharias, A.A. Zdziarski

Astrophysics of Galaxies

JWST resolves jet-driven H2 and ionized outflows in radio galaxy 3C305

B. Sebastian, P. M. Ogle, P. Guillard et al. (+17 more)

We present JWST MIRI MRS, NIRSpec, NIRCam, and MIRI imaging observations of 3C 305, a radio galaxy with a compact jet that is confined within the galaxy. We use the H2 0-0 S(1)-S(7) lines, several mid-IR fine-structure lines, and PAH emission in the MIRI MRS spectrum to conduct a multiphase study of the radio jet's impact on the interstellar medium. Multiple tracers, including H2/PAH 11.3 um and [Fe II] 5.34 um, provide evidence for shocks at the jet termination locations. Two Gaussian components are required to reproduce the warm H2 kinematics adequately, with one representing the bulk low-velocity component and the other corresponding to an outflow. The ionized gas reaches higher outflow velocities than the H2 gas, and the sharp increase in velocity at the jet hotspots points to jet-driven outflows. We fit the H2 excitation diagram with a power-law temperature distribution and find that the hotspots exhibit flatter slopes, indicating a larger warm/hot gas mass fraction at these locations. Our MAPPINGS line-ratio analysis indicates that most of the mid-IR ionized gas can be fit by a shock-plus-precursor model. We find that strong radiative losses dominated by line cooling, together with moderate kinetic power in the molecular and ionized gas outflows, can account for the estimated jet power, indicating high jet coupling efficiency in 3C 305. Together with other studies of multiphase gas, our results show that jets can efficiently shock-heat and accelerate the gas they encounter, driving massive, kiloparsec-scale, multiphase outflows.
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All authors B. Sebastian, P. M. Ogle, P. Guillard, L. Lanz, R. Morganti, V. Reynaldi, I. E. Lopez, B. Emonts, S. Garcia-Burillo, C. Tadhunter, C. P. O'Dea, S. Baum, F. R. Faifer, A. Labiano, M. Lehnert, A. Togi, K. Alatalo, P. Appleton, R. Bhutkar, E. Egami

Cosmology and Nongalactic Astrophysics

Probing Kinematic Anisotropies in the Stochastic Gravitational Wave Background with the SKA

N. M. J. Cruz, Ameek Malhotra, Gianmassimo Tasinato et al. (+1 more)

Pulsar Timing Arrays (PTAs) and astrometric surveys provide complementary probes of the nanohertz stochastic gravitational-wave background (SGWB). A primary target is the kinematic dipole induced by the Solar System's motion, whose detection would confirm the SGWB's cosmological origin. We forecast the sensitivity of the Square Kilometre Array Observatory (SKAO) using optimal estimators and Fisher techniques, considering both the baseline AA4 configuration and an optimistic 1000 pulsar scenario, including the potential gain from combining with Gaia-like astrometry. While SKAO will substantially improve constraints on SGWB anisotropies, even joint analyses remain below the sensitivity required to detect the kinematic dipole, motivating new observational and analysis strategies to fully exploit this signal.
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All authors N. M. J. Cruz, Ameek Malhotra, Gianmassimo Tasinato, Ivonne Zavala

High Energy Astrophysical Phenomena

Hybrid radio and particle detection of air showers: potential for ultra-high-energy photon identification

Paul Minodier, Kaoru Takahashi, Kumiko Kotera et al. (+1 more)

The autonomous radio-detection of extensive air showers initiated by ultra-high-energy (UHE) particles arriving with very inclined zenith angles has seen significant advancements in recent years, with several large-scale surface arrays planned and prototypes already in operation. In this work, we examine whether these radio detectors, supplemented by scintillators, could serve as competitive UHE photon detectors. Indeed, for inclined showers, radio emissions can be detected by antennas for both cosmic-ray and photon primaries, while the muon-rich signatures of the former would typically trigger the scintillators. Using two key observables – the total root mean square of the radio signal and the total energy deposit recorded in the scintillators – we show that effective separation between the two types of showers could be achieved in a hybrid radio antenna and scintillator setup. As a case study, we apply this method to a hypothetical hybrid array of radio antennas, complemented by Telescope Array-like scintillators, with the layout of the prototype of the Giant Radio Array for Neutrino Detection (GRAND), GRANDProto300. Our estimates show that such a hybrid array could set competitive upper limits on the integral photon flux in the energy range of approximately 0.3 to 3 EeV.
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All authors Paul Minodier, Kaoru Takahashi, Kumiko Kotera, Takashi Sako

Astrophysics of Galaxies

Impact of Anomalous Microwave Emission (AME) on Radio Spectral Energy Distributions: SKA Observations of Galaxies Near and Far

Ilsang Yoon, Eric Murphy, Caroline Bot et al. (+1 more)

Radio continuum emission powered by the thermal bremsstrahlung process is a clean, dust-free tracer of star formation in galaxies. However, the existence of anomalous microwave emission (AME) that is also prominent in a similar frequency range may challenge the use of thermal radio continuum emission to measure the star formation rates of galaxies. So while the nature of AME and the ISM conditions that lead to strong observable AME are still not well understood, the impact of AME on the radio emission from galaxies needs to be investigated for the SKA, which will be sensitive to large numbers of faint, high-redshift galaxies. In this chapter, we compute the observable flux density of free-free emission and AME and investigate the impact of AME on the galaxy radio spectral energy distribution for given observing frequencies and redshifts. Our conclusion is that (1) significance of AME is determined by the size of the AME region relative to the observing beam and ISM hydrogen column density, (2) thermal free-free emission dominates the radio continuum emission for distant galaxies at $\approx 10$ GHz frequency with negligible contribution from AME, (3) high-angular resolution observation of nearby galaxies resolving individual star forming region may need multi-frequency observations to avoid a potential bias from AME in the measure of star formation rate from single frequency observation.
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All authors Ilsang Yoon, Eric Murphy, Caroline Bot, Lucie Correia

Instrumentation and Methods for Astrophysics

On-Sky Single-photon Time resolution of 35 ps with White Rabbit synchronization: towards the measurement of the size of a White Dwarf star

F. Izraelevitch-Patitucci, S. Tolila, I. Ellafi et al. (+7 more)

The IC4Stars (Intensity Correlation for Stars) project aims to measure the diameter of the white dwarf star Sirius B, using Intensity Interferometry. In this work we present our latest efforts and the milestones achieved in the last year. We report laboratory characterization of the single-photon detectors, TDC and synchronization electronics. We describe an observation campaign where we demonstrated on-sky time resolution below 35 ps RMS, synchronizing two TDCs using the White Rabbit protocol and a 30 m telecom fiber. We developed the data acquisition of the raw time tags, and an algorithm to compute the second-order correlation function.
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All authors F. Izraelevitch-Patitucci, S. Tolila, I. Ellafi, J.-P. Rivet, M. Hugbart, G. Labeyrie, O. Lai, A. Zmija, W. Guerin, R. Kaiser

Astrophysics of Galaxies

Compact radio galaxies: the case of FR0s

R. D. Baldi, A. Capetti, G. Giovannini et al. (+20 more)

Fanaroff-Riley type 0 (FR0) radio galaxies, a newly-identified and abundant population of low-power radio-loud active galactic nuclei, present a significant challenge to our understanding of radio galaxy evolution. Unlike their more extended FRI and FRII counterparts, FR0s are characterized by compact (from pc to a few kpc) radio morphologies with weak or absent large-scale jets, despite having optical host galaxy properties and central black hole masses similar to classical, more powerful radio galaxies. Their compactness and prevalence suggest they may represent an early stage of radio galaxy evolution or indicate a fundamentally different accretion and ejection mechanism. The Square Kilometre Array (SKA), with its continuum survey and VLBI capabilities, offers a transformative opportunity to study FR0 radio galaxies at unprecedented angular resolution and sensitivity. Milliarcsecond (mas) angular resolution VLBI observations will probe their parsec-scale structure, providing critical insights into the nature of their jets, accretion-ejection physics, and the interplay between nuclear activity and the surrounding environment. Continuum and polarization surveys will enable a systematic study of their population properties, distribution, and radio spectra across a wide range of redshifts in relation to other populations of radio galaxies.
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All authors R. D. Baldi, A. Capetti, G. Giovannini, S. Amarantidis, M. Brienza, G. Bruni, J. Chilufya, A. Costa, M. Gitti, D. V. Lal, G. Migliori, J. Moldon, M. Orienti, F. Panessa, I. Prandoni, M. Puig-Subirà, R. M. Samir, S. Shabala, F. Shankar, C. Spingola, F. Tavecchio, F. Ubertosi, B. Vaidya

Cosmology and Nongalactic Astrophysics

The PAU Survey and Euclid: Analysing photometric redshifts from realistically simulated narrow-band photometry with Flagship 2

A. Wittje, H. Hildebrandt, D. Navarro-Gironés et al. (+154 more)

The study of the large-scale structure of the Universe and the distribution of galaxies has been greatly advanced by the application of various types of photometric redshift estimation techniques. The Physics of the Accelerating Universe Survey (PAUS) is a state-of-the-art imaging survey, designed to provide high-quality photometric data in 40 optical narrow-band filters. In this paper, we present an in-depth analysis of the photometric redshifts obtained from PAUS using realistic simulations. Based on the Euclid Flagship 2 catalogue, we generate PAUS-like simulations with realistic photometric noise and target selection. The mock catalogue is used to explore the accuracy and precision of photometric redshifts of PAUS, investigating the impact of noise and depth, and combinations of broad- and narrow-band data. The simulations reproduce the observed PAUS performance well, with a robust photometric redshift scatter of $\sigma_{NMAD}/(1+z)\!=\!0.011$ for a mock subsample resembling the spectroscopic validation sample of the data. For the complete PAUS-like sample, which can only be evaluated in the simulation, we find $\sigma_{NMAD}/(1+z)\!=\!0.028$ for $i_{\rm AB}\!\lesssim\!23$ and outlier fractions below 10%. Forecasts indicate that including Euclid photometry in a joint analysis could further reduce scatter and outlier fractions, especially for faint galaxy populations. The hypothetical case of deeper PAUS observations over a limited sky area, forecasting the potential for future narrow- or medium-band surveys, in combination with Euclid's deep photometry, achieves scatter as low as $\sigma_{NMAD}/(1+z)\!=\!0.011$ and outlier fractions below 4% for $i_{\rm AB}\!<\!23.5$.
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All authors A. Wittje, H. Hildebrandt, D. Navarro-Gironés, E. J. Gonzalez, J. L. van den Busch, E. Gaztanaga, M. Eriksen, A. H. Wright, R. Casas, J. Carretero, F. J. Castander, E. Fernandez, P. Fosalba, J. García-Bellido, H. Hoekstra, R. Miquel, C. Padilla, P. Renard, E. Sanchez, I. Sevilla-Noarbe, P. Tallada-Crespí, B. Altieri, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, S. Bardelli, P. Battaglia, A. Biviano, M. Bolzonella, E. Branchini, M. Brescia, S. Camera, G. Cañas-Herrera, V. Capobianco, C. Carbone, V. F. Cardone, M. Castellano, G. Castignani, S. Cavuoti, A. Cimatti, C. Colodro-Conde, G. Congedo, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Crocce, H. Degaudenzi, G. De Lucia, H. Dole, F. Dubath, C. A. J. Duncan, X. Dupac, S. Escoffier, M. Farina, R. Farinelli, S. Farrens, F. Faustini, S. Ferriol, F. Finelli, S. Fotopoulou, N. Fourmanoit, M. Frailis, M. Fumana, S. Galeotta, K. George, B. Gillis, C. Giocoli, J. Gracia-Carpio, A. Grazian, F. Grupp, S. V. H. Haugan, W. Holmes, F. Hormuth, A. Hornstrup, K. Jahnke, M. Jhabvala, B. Joachimi, S. Kermiche, A. Kiessling, M. Kilbinger, B. Kubik, M. Kümmel, H. Kurki-Suonio, A. M. C. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, O. Mansutti, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, E. Medinaceli, S. Mei, M. Melchior, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, L. Moscardini, R. Nakajima, C. Neissner, S.-M. Niemi, S. Paltani, F. Pasian, K. Pedersen, V. Pettorino, A. Pezzotta, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, F. Raison, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, R. Saglia, Z. Sakr, A. G. Sánchez, D. Sapone, B. Sartoris, P. Schneider, T. Schrabback, A. Secroun, E. Sefusatti, E. Sihvola, P. Simon, C. Sirignano, G. Sirri, A. N. Taylor, H. I. Teplitz, I. Tereno, N. Tessore, S. Toft, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, J. Valiviita, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, G. Zamorani, F. M. Zerbi, E. Zucca, A. Montoro, M. Sereno