Research Articles (Physics)

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Mightee-H i: the star-forming properties of H i-selected galaxies
(Oxford University Press, 2026) Tudorache, Madalina N.; Jarvis, Matthew J.; Ponomareva, Anastasia A.; Heywood, Ian; Maddox, Natasha; Glowacki, Marcin; Frank, Bradley S.; Baes, Maarten; Dav́e, Romeel; Jung, Seoyoung Lyla; Maksymowicz-Maciata, Michalina; Pan, Hengxing; Spekkens, Kristine
The interplay between atomic gas and the star formation history (SFH) of a galaxy are intrinsically linked, and we need to decouple these dependencies to understand their role in galaxy formation and evolution. In this paper, we analyse the SFH of 203 galaxies from the MIGHTEE-H i Survey Early Science Release data, cross-matched to with multiwavelength photometry across the COSMOS and XMM-LSS fields. We focus on the relationships between H i properties and star formation, with a sample which primarily traces gas-rich, star-forming systems at low redshift, extending to low stellar masses and probing regimes that are difficult to access with optically selected samples. A strong correlation emerges between a galaxy’s H i-to-stellar mass ratio and the time of formation, alongside an inverse correlation between stellar mass and time of formation, regardless of the inferred SFH. Additionally, galaxies with lower stellar masses and higher H i-to-stellar mass ratios exhibit longer gas depletion times compared to more massive galaxies, which appear to have depleted their gas and formed stars more efficiently. This suggests that smaller, gas-rich galaxies have higher depletion times due to shallower potential wells and less efficient star formation. Within this H i-selected sample, the efficiency of star formation is regulated primarily by stellar mass and gas fraction, with low-mass galaxies retaining extended atomic reservoirs due to inefficient conversion of H i into stars.
Phantom crossing or dark interaction?
(Institute of Physics, 2026) Guedezounme, Sêcloka L; Dinda, Bikash R; Maartens, Roy
Recent results from DESI BAO measurements, together with Planck CMB and Pantheon+ data, suggest that there may be a 'phantom' phase (wde< -1) in the expansion of the Universe. This inference follows when the w0,wa parametrization for the dark energy equation of state wdeis used to fit the data. Since phantom dark energy in general relativity is unphysical, we investigate the possibility that the phantom behaviour is not intrinsic, but effective — due to a non-gravitational interaction between dark matter and non-phantom dark energy. To this end, we assume a physically motivated thawing quintessence-like form of the intrinsic dark energy equation of state wde. Then we use a w0,wa model for theeffectiveequation of state of dark energy. We find that the data favours a phantom crossing for the effective dark energy, but only at low significance. The intrinsic equation of state of dark energy is non-phantom, without imposing any non-phantom priors. A nonzero interaction is favoured at more than 3σatz∼ 0.3. The energy flows from dark matter to dark energy at early times and reverses at later times.
Cosmological back-reaction of baryons on dark matter in the CAMELS simulations
(Oxford University Press, 2026) Davé, Romeel; Gebhardt, Matthew; Anglés-Alcázar, Daniel
Baryonic processes such as radiative cooling and feedback from massive stars and active galactic nuclei directly redistribute baryons in the Universe but also indirectly redistribute dark matter due to changes in the gravitational potential. In this work, we investigate this ‘back-reaction’ of baryons on dark matter using thousands of cosmological hydrodynamic simulations from the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) project, including parameter variations in the SIMBA, IllustrisTNG, ASTRID, and Swift-EAGLE galaxy formation models. Matching haloes to corresponding N-body (dark matter-only) simulations, we find that virial masses decrease owing to the ejection of baryons by feedback. Relative to N-body simulations, halo profiles show an increased dark matter density in the centre (due to radiative cooling) and a decrease in density farther out (due to feedback), with both effects being strongest in SIMBA ((Formula presented) 450 per cent increase at (Formula presented)). The clustering of dark matter strongly responds to changes in baryonic physics, with dark matter power spectra in some simulations from each model showing as much as 20 per cent suppression or increase in power at (Formula presented) Mpc(Formula presented) relative to N-body simulations. We find that the dark matter back-reaction depends intrinsically on cosmology ((Formula presented) and (Formula presented)) at fixed baryonic physics, and varies strongly with the details of the feedback implementation. These results emphasize the need for marginalizing over uncertainties in baryonic physics to extract cosmological information from weak lensing surveys as well as their potential to constrain feedback models in galaxy evolution.
Calibration-independent consistency test of BAO and SNIa data: update
(Institute of Physics, 2026) Dinda, Bikash; Maartens, Roy; Clarkson, Chris
In a recent paper 2509.19899, we presented a new method to test the consistency between uncalibrated BAO and SNIa data through a common parameter, the Alcock-Paczynski variable. Using Gaussian Processes, we can determine if various datasets are consistent, independently of dark energy or modified gravity models, and of the sound horizon and SNIa peak magnitude. We found that the DES-Y5 SNIa data showed non-negligible tension with other datasets. However, the recent update DES-Dovekie removes this tension. We find that all uncalibrated data from DESI DR2 BAO and three SNIa datasets, Union3, Pantheon+, and DES-Dovekie, are consistent with each other within ∼ 1σ.
Applications of 1.4 GHz diagnostics to Type Ia Supernova host galaxies
(Oxford University Press, 2026) Jarvis, Matthew; Whittam, Imogen; Ramaiya, Shruti
Type Ia supernova (SN Ia) standardization parameters exhibit evidence for systematic variation across the host galaxy star formation rate–stellar mass (SFR(Formula presented)) plane, motivating the incorporation of galaxy SFR information in cosmological inference. SFRs are commonly estimated via spectral energy distribution (SED) fitting with far-infrared (FIR) measurements to account for dust-obscured star formation. Such FIR coverage will, however, be limited for upcoming time-domain surveys such as the Rubin Observatory Legacy Survey of Space and Time (LSST), necessitating the use of alternative SFR tracers. Here, we reconstruct the SFR–(Formula presented) plane using 1.4 GHz diagnostics, to test the consistency of host classifications against FIR-constrained SED-based estimates. Within this plane, SN Ia host galaxies are divided into three regions: Region 1 (low mass), Region 2 (high-mass star forming), and Region 3 (high-mass passive). We find that (Formula presented) per cent of SN hosts retain identical region assignments when using radio versus FIR-constrained SED-derived SFRs. Measuring SN Ia nuisance parameters ((Formula presented)) within each subregion, we find consistent values between the two SFR–(Formula presented) plane reconstructions, indicating limited sensitivity to SFR estimator choice, with the largest deviations in Region 3 at (Formula presented). Across the three 1.4 GHz SFR–(Formula presented) subregions, we confirm the region-dependent variation in SN Ia standardization parameters – particularly (Formula presented) – reported in our earlier SED-based analysis. With near-complete radio coverage of the LSST footprint anticipated from current and forthcoming radio continuum surveys (e.g. Square Kilometre Array), radio SFR calibrations will become an increasingly useful and scalable approach to host galaxy classification, supporting the construction of robust SN Ia subsamples for precision cosmology.
The tracking tapered gridded estimator for the 21-cm power spectrum from the Murchison Widefield Array (MWA) drift scan observations – III. Improved upper limits at z = 8.2 from multiple pointings
(Oxford University Press, 2026) Chatterjee Suman; Sarkar Shouvik; Choudhuri Samir
We analyse zenith-pointing (δ = −26.7◦ ) Murchison Widefield Array (MWA) νc = 154.2 MHz drift scan observations covering 349.0◦ ≤ α ≤ 70.0◦ with 163 pointing centres (PCs) spaced by 0.5◦. We measure D , the mean-squared angular brightness temperature fluctuations, as a function of α. A broad peak at α ≈ 50.0◦ corresponds to the bright extended source Fornax A in the main lobe of the primary beam. A smaller peak at α ≈ 5.0◦ possibly corresponds to Fornax A in the first sidelobe. For α ≤ 22.0◦ and ≥ 200, we find D ∝ 2, which we interpret as Poisson fluctuations from point sources. We present 2(k), the mean-squared 21-cm brightness temperature fluctuations from the Epoch of Reionization, as a function of α. Fornax A causes strong contamination near α ≈ 50.5◦, elsewhere several PCs are consistent with noise. The range 358.5◦ ≤ α ≤ 11.5◦ is relatively foreground-free and best suited for EoR science. The PC at α = 11.0◦ yields the best 2σ upper limit 2 UL(k) = (173.13)2 mK2 at k = 0.161 Mpc−1. We incoherently combine 23 PCs to obtain 2 UL(k) = (98.67)2 mK2 at k = 0.156 Mpc−1. This is the tightest upper limit from the MWA, being ≈ 3 times lower than earlier MWA limits, but ≈ 2 and ≈ 21 times higher than the LOFAR and HERA limits, respectively, and ≈ 3 orders of magnitude above theoretical predictions
MIGHTEE: the evolving radio luminosity functions of star-forming galaxies to z ∼ 4.5 and the cosmic history of star formation
(Oxford University Press, 2026) Thykkathu, Nijin J; Jarvis, Matt J; Whittam, Imogen H; Hale, C.L; Matthews, A.M; Heywood, I; Malefahlo, Eliab; Varadaraj, R.G.; Stylianou, N; Pearson, Chris; Seymour, Nick; Vaccari, Mattia
A key question in extragalactic astronomy is how the star formation rate density (SFRD) evolves over cosmic time. A powerful way of addressing this question is using radio-continuum observations, where the radio waves are unaffected by dust and are able to reach sufficient resolution to resolve individual galaxies. We present an investigation of the 1.4 GHz radio luminosity functions (RLFs) of star-forming galaxies (SFGs) and active galactic nuclei (AGNs) using deep radio continuum observations in the COSMOS and XMM–LSS fields, covering a combined area of (Formula presented). These data enable the most accurate measurement of the evolution in the SFRD from mid-frequency radio continuum observations. We model the total RLF as the sum of evolving SFG and AGN components, negating the need for individual source classification. We find that the SFGs have systematically higher space densities at fixed luminosity than found in previous radio studies, but consistent with more recent studies with MeerKAT. We attribute this to the excellent low-surface brightness sensitivity of MeerKAT. We then determine the evolution of the SFRD. Adopting the far-infrared–radio correlation results in a significantly higher SFRD at (Formula presented), compared to combined UV and far-infrared measurements. However, using more recent relations for the correlation between star formation rate and radio luminosity, based on full spectral energy distribution modelling, can resolve this apparent discrepancy. Thus, radio observations provide a powerful method of determining the total SFRD in the absence of dust-sensitive far-infrared data.
Euclid preparation: LXXXV. Toward a DR1 application of higher-order weak lensing statistics
(EDP Sciences, 2026) Bouchè F.; Bouchè F.; Martinet N.; Castiblanco L.; Uhlemann C.
This is the second paper in the HOWLS (higher-order weak lensing statistics) series exploring the usage of non-Gaussian statistics for cosmology inference within Euclid. With respect to our first paper, we develop a full tomographic analysis based on realistic photometric redshifts that allows us to derive Fisher forecasts in the (8, w0) plane for a Euclid-like data release 1 (DR1) setup. We find that the five higher-order statistics (HOS) that satisfy the Gaussian likelihood assumption of the Fisher formalism (one-point probability distribution function, 1-norm, peak counts, Minkowski functionals, and Betti numbers) each outperform the shear two-point correlation functions by a factor of 2.5 on the w0 forecasts, with only marginal improvement when used in combination with two-point estimators, suggesting that every HOS is able to retrieve both the non-Gaussian and Gaussian information of the matter density field. The similar performance of the different estimators is explained by a homogeneous use of multi-scale and tomographic information, optimized to lower computational costs. These results hold for the three mass mapping techniques of the Euclid pipeline, aperture mass, Kaiser-Squires, and Kaiser-Squires plus, and they are unaffected by the application of realistic star masks. Finally, we explored the use of HOS with the Bernardeau-Nishimichi-Taruya (BNT) nulling scheme approach, finding promising results toward applying physical scale cuts to HOS.
Euclid: VI. NISP-P optical ghosts
(EDP Sciences, 2026) Schirmer M.; Schirmer M.; Okumura K.; Venemans B.; Jahnke K.
The Near-Infrared Spectrometer and Photometer (NISP) on board Euclid includes several optical elements in its path that introduce artefacts into the data from non-nominal light paths. To ensure uncontaminated source photometry, these artefacts must be accurately accounted for. This paper focuses on two specific optical features in NISP's photometric data (NISP-P): ghosts caused by the telescope's dichroic beamsplitter, and the bandpass filters within the NISP fore-optics. Both ghost types exhibit a characteristic morphology and are offset from the originating stars. The offsets are well modelled using 2D polynomials; only stars brighter than approximately 10 magnitudes in each filter produce significant ghost contributions. The masking radii for these ghosts depend on both the source-star brightness and the filter wavelength, ranging from 20 to 40 pixels. We present the final relations and models used in the near-infrared (NIR) processing function (PF) to mask these ghosts for Euclid's Quick Data Release (Q1).
Deformation of the 01,2+ states in 110cd from low-energy coulomb excitation
(Elsevier B.V., 2026) Wrzosek-Lipska, K.; Piętka, Iwona Z.; Próchniak, Leszek; Garrett, Paul E.; Zielińska, Magda; Abraham, Tomasz; Allmond, James. M.; Bello-Garrote, Frank Leonel; Bidaman, Harris.; Bildstein, Vinzenz; Buck, Samantha; Burbadge, Christina.; Chiari, Massimo; Coleman, R. J.; Colombi, Giacomo; Colucci, Giulia; Diaz-Varela, Alejandra; Doherty, Daniel T.; Dutt, Sunil; Hadyńska-Klek, Katarzyna; Heery, Jacob A.M.; Hlebowicz, M.; Hymers, Devin; Iwanicki, Jędrzej.; Jaworski, Grzegorz; Jigmeddorj, Badamsambuu.; Kalaydjieva, Desislava; Kisieliński, Maciej; Komorowska, Malgorzata; Kopeć, N.; Kowalczyk, Michał; Kowalska, J. A.; Krutul-Bitowska, Katarzyna Z.; Kumar, Rakesh Rakesh; Mai Quynh, A.; Marchini, Naomi; Marchlewski, T.; Mashtakov, Konstantin R.; Matejska-Minda, M.; Michelagnoli, Caterina; Nannini, Adriana; Napiorkowski, Paweł Jan; Olaizola, Bruno.; Oleszczuk, F.; Palacz, Marcin.; Pasquali, E.; Peters, Erin E.; Rocchini, Marco; Sahin, Eda.; Samorajczyk-Pyśk J.; Saxena, Mansi; Stolarz, Anna; Srebrny, Julian; Tucholski, Andrzej; Trzcińska, Agnieszka; Venhart, Martin; Wood, John L.; Yates, Steven W.; Zidar, Tammy.
Electromagnetic properties of 110Cd were studied via low-energy Coulomb excitation with 32S and 14N beams. Magnitudes and relative signs of eight E 2 matrix elements, including quadrupole moments of the 21+ and 22+ states, were determined using the least-squares code GOSIA. From those, quadrupole deformation parameters of the 01,2,3+ states were inferred, providing for the first time conclusive evidence for the non-axial character of the ground state in 110Cd. The experimental results were compared with new calculations using the general quadrupole collective Bohr Hamiltonian model with SLy4 and UNEDF0 interactions. The non-axiality of the ground state is reproduced by the present calculations, independently of the interaction used.
Euclid preparation: LXXX. Overview of euclid infrared detector performance from ground tests
(EDP Sciences, 2026) Karagiannis D.
This paper describes the objectives, design, and findings of the pre-launch ground characterisation campaigns of the Euclid infrared detectors. The aim of the ground characterisations is to evaluate the performance of the detectors, to calibrate the pixel response, and to derive the pixel response correction methods. The detectors have been tested and characterised in the facilities set up for this purpose. The pixel properties, including baseline, bad pixels, quantum efficiency, inter pixel capacitance, quantum efficiency, dark current, readout noise, conversion gain, response non-linearity, and image persistence were measured and characterised for each pixel. We describe in detail the test flow definition that allows us to derive the pixel properties and we present the data acquisition and data quality check software implemented for this purpose. We also outline the measurement protocols of all the pixel properties presented and we provide a comprehensive overview of the performance of the Euclid infrared detectors as derived after tuning the operating parameters of the detectors. The main conclusion of this work is that the performance of the infrared detectors Euclid meets the requirements. Pixels classified as non-functioning accounted for less than 0.2% of all science pixels. The interpixel capacitance (IPC) coupling is minimal, the cross-talk between adjacent pixels is less than 1% between adjacent pixels, and 95% of the pixels show a quantum efficienty (QE) greater than 80% across the entire spectral range of the Euclid mission. The conversion gain is approximately 0.52 ADU/e-, with a variation of less than 1% between channels of the same detector. The reset noise is approximately equal to 23 ADU rms after reference pixel correction. The readout noise of a single frame is approximately 13 e- rms while the signal estimator noise is measured at 7 e- rms in photometric mode and 9 e- rms in spectroscopic acquisition mode. The deviation from linear response at signal levels up to 80 ke- is less than 5% for 95% of the pixels. Median persistence amplitudes are less than 0.3% of the signal, though persistence exhibits significant spatial variation and differences between detectors.
Discovery of a years-delayed radio flare from an unusually slowly evolving tidal disruption event candidate
(American Astronomical Society, 2026) Zhang, Zhumao; Shu, Xinwen; Yang, Lei; Sun, Luming; Ding, Hucheng; Yan, Lin; Jiang, Ning; An, Fangxia; Shu, Xinwen; Zhang, Zhumao; Chandola, Yogesh; Wu, Zhongzu; Liu, Daizhong; Dou, Liming; Wang, Jianguo; Wang, Yibo; Yang, Chenwei; Li, Di; Zhou, Tianyao; Peng, Fang Kun; Wang, Tinggui; Wang, Tinggui
SDSS J1115+0544 is a unique low-ionization nuclear emission-line region galaxy with energetic ultraviolet (UV), optical, and mid-infrared outbursts occurring in its nucleus. We present the results from an analysis of multiwavelength photometric and radio follow-up observations with a time span of ≈9 yr since its discovery. We find that following a luminosity plateau of ≈500 days, the UV/optical emission has decayed back to the preoutburst level, suggesting that the nuclear outburst might be caused by a stellar tidal disruption event (TDE). In this case, J1115+0544 could be an unusually slowly evolving optical TDE with longest rise and decline time scales ever found. Three years later than the optical peak, a delayed radio brightening was found with a luminosity as high as νL ν (5.5 GHz) ∼ 1.9 × 1039 erg s−1. Using a standard equipartition analysis, we find that the outflow powering the radio emission was launched at t ≳ 1150 days with a velocity of v ≲ 0.1c and a minimal kinetic energy of E K ≳ 3 × 1049 erg. The delayed radio brightening coupled with the disappearing plateau in the UV/optical light curves is consistent with the scenario involving delayed ejection of an outflow from a state transition in the disk. SDSS J1115+0544 is the first TDE candidate displaying both a short-lived UV/optical plateau emission and a late-time radio brightening. Future radio observations of these TDEs in the postplateau decay phase will help to establish the connection between outflow launching and changes in accretion rate
Meta-learning for cosmological emulation: rapid adaptation to new lensing kernels
(Oxford University Press, 2026) Bull, Philip; MacMahon-Gellér, Charlie; Leonard, C Danielle
Theoretical computation of cosmological observables is an intensive process, restricting the speed at which cosmological data can be analysed and cosmological models constrained, and therefore limiting research access to those with high performance computing infrastructure. Whilst the use of machine learning to emulate these computations has been studied, most existing emulators are specialized and not suitable for emulating a wide range of observables with changing physical models. Here, we investigate the Model-Agnostic Meta-Learning algorithm (MAML) for training a cosmological emulator. MAML attempts to train a set of network parameters for rapid fine-tuning to new tasks within some distribution of tasks. Specifically, we consider a simple case where the galaxy sample changes, resulting in a different redshift distribution and lensing kernel. Using MAML, we train a cosmic shear angular power spectrum emulator for rapid adaptation to new redshift distributions with only $O(100)$ fine-tuning samples, whilst not requiring any parametrization of the redshift distributions. We compare the performance of the MAML emulator to two standard emulators, one pre-trained on a single redshift distribution and the other with no pre-training, both in terms of accuracy on test data, and the constraints produced when using the emulators for cosmological inference. We observe that within an Markov Chain Monte Carlo analysis, the MAML emulator is able to better reproduce the fully theoretical posterior, achieving a Battacharrya distance from the fully theoretical posterior in the $S_8$ – $\Omega _m$ plane of 0.008, compared to 0.038 from the single-task pre-trained emulator and 0.243 for the emulator with no pre-training.
Universality of r-process elemental abundances: a well-regulated conspiracy of astrophysical and nuclear properties
(Institute of Physics, 2026) Orce, José Nicolás
The isovector distribution of thousands of products of electric dipole (E1) matrix elements connecting the ground and first excited states through virtual excitations in the giant dipole resonance (GDR) region is presented for the first time in selected p and sd shell nuclei from 1ℏω shell-model calculations. A smaller nuclear dipole polarizability for the first excited level with respect to the ground state arises from the destructive contribution of off-diagonal E1 matrix elements. This results in a larger symmetry energy consistent with data from GDRs built on excited states of heavier nuclei at temperatures of 0.5 ⪅ T ⪅ 1 MeV and previous calculations of the temperature dependence of the symmetry energy in medium-mass nuclei within the quasiparticle random phase approximation and the shell-model Monte Carlo. The corresponding reduction of the binding energy in the Bethe-Weizsäcker semi-empirical mass formula yields a drop of radiative neutron capture rates and the shift of the neutron drip line towards the line of stability; in turn, providing a plausible explanation for the origin of the universality of elemental abundances by sharply constraining the reaction network flow for r-process nucleosynthesis.
Euclid preparation: LXXX. Overview of Euclid infrared detector performance from ground tests
(EDP Sciences, 2026) Karagiannis D.; Kubik B; Barbier R
This paper describes the objectives, design, and findings of the pre-launch ground characterisation campaigns of the Euclid infrared detectors. The aim of the ground characterisations is to evaluate the performance of the detectors, to calibrate the pixel response, and to derive the pixel response correction methods. The detectors have been tested and characterised in the facilities set up for this purpose. The pixel properties, including baseline, bad pixels, quantum efficiency, inter pixel capacitance, quantum efficiency, dark current, readout noise, conversion gain, response non-linearity, and image persistence were measured and characterised for each pixel. We describe in detail the test flow definition that allows us to derive the pixel properties and we present the data acquisition and data quality check software implemented for this purpose. We also outline the measurement protocols of all the pixel properties presented and we provide a comprehensive overview of the performance of the Euclid infrared detectors as derived after tuning the operating parameters of the detectors. The main conclusion of this work is that the performance of the infrared detectors Euclid meets the requirements. Pixels classified as non-functioning accounted for less than 0.2% of all science pixels. The interpixel capacitance (IPC) coupling is minimal, the cross-talk between adjacent pixels is less than 1% between adjacent pixels, and 95% of the pixels show a quantum efficienty (QE) greater than 80% across the entire spectral range of the Euclid mission. The conversion gain is approximately 0.52 ADU/e-, with a variation of less than 1% between channels of the same detector. The reset noise is approximately equal to 23 ADU rms after reference pixel correction. The readout noise of a single frame is approximately 13 e- rms while the signal estimator noise is measured at 7 e- rms in photometric mode and 9 e- rms in spectroscopic acquisition mode. The deviation from linear response at signal levels up to 80 ke- is less than 5% for 95% of the pixels. Median persistence amplitudes are less than 0.3% of the signal, though persistence exhibits significant spatial variation and differences between detectors.
Euclid preparation: LXXXIV. The flat-sky approximation for the clustering of Euclids photometric galaxies
(EDP Sciences, 2026) Karagiannis D.; Matthewson W.L.; Durrer R.
We compared the performance of the flat-sky approximation and Limber approximation for the clustering analysis of the photometric galaxy catalogue of Euclid. We studied a 6-bin configuration, representing the first data release (DR1), and a 13-bin configuration, representing the third and final data release (DR3). We find that the Limber approximation is sufficiently accurate for the analysis of the wide bins of DR1. Instead, the 13 bins of DR3 cannot be modelled accurately with the Limber approximation. Instead, the flat-sky approximation is accurate to below 5% in recovering the angular power spectra of galaxy number counts in both cases and can be used to simplify the computation of the full power spectrum in harmonic space for the data analysis of DR3.
Euclid preparation: LXXXV. Toward a DR1 application of higher-order weak lensing statistics
(EDP Sciences, 2026) Karagiannis D.; Vinciguerra S.; Bouchè F.
This is the second paper in the HOWLS (higher-order weak lensing statistics) series exploring the usage of non-Gaussian statistics for cosmology inference within Euclid. With respect to our first paper, we develop a full tomographic analysis based on realistic photometric redshifts that allows us to derive Fisher forecasts in the (8, w0) plane for a Euclid-like data release 1 (DR1) setup. We find that the five higher-order statistics (HOS) that satisfy the Gaussian likelihood assumption of the Fisher formalism (one-point probability distribution function, 1-norm, peak counts, Minkowski functionals, and Betti numbers) each outperform the shear two-point correlation functions by a factor of 2.5 on the w0 forecasts, with only marginal improvement when used in combination with two-point estimators, suggesting that every HOS is able to retrieve both the non-Gaussian and Gaussian information of the matter density field. The similar performance of the different estimators is explained by a homogeneous use of multi-scale and tomographic information, optimized to lower computational costs. These results hold for the three mass mapping techniques of the Euclid pipeline, aperture mass, Kaiser-Squires, and Kaiser-Squires plus, and they are unaffected by the application of realistic star masks. Finally, we explored the use of HOS with the Bernardeau-Nishimichi-Taruya (BNT) nulling scheme approach, finding promising results toward applying physical scale cuts to HOS.
Primary beam chromaticity in HIRAX. I. characterization from simulations and power spectrum implications
(American Astronomical Society, 2026) Dlamini, Simthembile; Santos, Mario G.; Sampath, Ajith
The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is an upcoming radio interferometric telescope designed to constrain dark energy through the 21 cm intensity mapping of baryon acoustic oscillations. Instrumental systematics must be controlled and carefully characterized to measure the 21 cm power spectrum with fidelity and achieve high-precision constraints on the cosmological parameters. The chromaticity of the primary beam is one such complicated systematic, which can leak the power of spectrally smooth foregrounds beyond the ideal horizon limits due to the complex spatial and spectral structures of the side lobes and the main lobe. This paper investigates the chromaticity of the HIRAX Stokes I primary beam and its impact on the accurate measurement of the 21 cm power spectrum. To investigate the effect of chromaticity on the 21 cm power spectrum, we present a physically motivated beam modeling technique that utilizes a flexible basis derived from traditional optics, allowing for the accounting of higher-order radial and azimuthal structures in the primary beam. We investigate the impact of imperfect knowledge of the main lobe and side lobes' chromaticity in the power spectrum space by subtracting a simple foreground model in simulated snapshot visibilities to recover the H i power spectrum. Additionally, we find that modeling up to the octupolar azimuthal order feature (fourth-order angular variation) in the primary beam is sufficient to reduce the leakage outside the wedge with minimal bias.
Joint Bayesian calibration and map-making for intensity mapping experiments
(Oxford University Press, 2026) Bull, Philip; Santos, Mario G; Zhang, Zheng
Line-intensity mapping (LIM) is an emerging cosmological technique that traces large-scale structure through the integrated spectral-line emission of unresolved sources. Reconstructing unbiased sky maps requires careful joint treatment of instrumental calibration and map-making, a task made challenging by time-varying receiver gains, thermal drifts, and correlated $1/f$ noise intrinsic to single-dish radio telescopes. We present a Bayesian framework for joint calibration and map-making using Gibbs sampling, giving access to the full joint posterior of calibration and sky map parameters. Our data model is grounded in the radiometer equation, capturing the coupling between noise level and system temperature without assuming a fixed noise amplitude. Gain and system temperature are estimated via an iterative generalized least-squares scheme, while absolute flux calibration is achieved either with external calibrators or via known signal injections such as noise diodes. We further introduce a $1/f$ noise model that avoids spurious periodic correlations arising from the common assumption of a diagonally structured noise covariance in the frequency domain. The workflow is implemented in an efficient software package using the Levinson algorithm and a polynomial emulator to reduce computational cost. Demonstrated on simulations representative of MeerKLASS single-dish observations, the framework generalizes to other single-dish surveys and to cross-correlation and interferometric data.
TESS observations of newly discovered pulsating A and F stars
(Cambridge University Press, 2026) Kilkenny, David; Baran, Andrzej; Vercher, Jonah
We have analysed photometric data from a sample of pulsating stars observed by the Transiting Exoplanet Survey Satellite. By applying Fourier and prewhitening techniques, we extracted the significant frequencies for each star. We investigated the presence of rotationally split multiplets and evaluated frequency spacings using the Kolmogorov-Smirnov test. These analyses allow us to estimate stellar parameters such as the large frequency spacing, which in turn provides insights into the stellar mean densities. However, identifying clear multiplets and frequency spacings in δ Scuti stars remains challenging due to the complexity of their oscillation spectra. Our rotationally-split mode findings are yet to be confirmed, while the K-S test revealed no convincing large frequency spacings that could be used toward mass estimation. We derived orbital periods for stars we identified to be in binary systems. We provide spectral type classifications to confirm the δ Sct and/or γ Dornature of the stars we found. Out of 43 stars presented in this paper, 18 are identified as δ Sct/γ Dor hybrids (including five candidates), 20 as δSct stars, one as a γ Dor star and four as binary systems without any signature of pulsation.

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