Research Articles (Physics)

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Estimation of backgrounds from jets misidentified as τ-leptons using the universal fake factor method with the atlas detector
(Springer Nature, 2025) Zormpa O.; Zou W.; Zormpa O.; Zorbas T.G.; Zoch K.
Processes with τ-leptons in the final state are important for Standard Model measurements and searches for physics beyond the Standard Model. The ATLAS experiment at the Large Hadron Collider observes τ-leptons produced in proton–proton collisions only through their decay products. Data analyses involving hadronically decaying τ-leptons face challenges due to backgrounds from jets misidentified as τ-leptons that are not modelled reliably by Monte Carlo simulations. Data-driven methods such as the fake-factor method allow such misidentified backgrounds to be predicted by measuring transfer factors, known as fake factors, in data from dedicated regions. This paper describes a refined technique for determining the fake factors, the Universal Fake Factor method. It evaluates the fake factors for a signal region by using fake factors from samples enriched in different sources of jets misidentified as τ-leptons (light-quark, gluon, b-quark, and pile-up jets). Each fake factor is calculated as a linear combination of fake factors measured in these different enriched samples. For the full Run 2 data set, the systematic uncertainty of the calculated fake factors, evaluated using W(μν) enriched event sample, ranges from 15 to 35% depending on the τ-lepton’s transverse momentum and charged-particle decay multiplicity.
HETDEX public data release 1: source catalog 2 and data cubes from ∼90 deg2 of integral-field optical spectroscopy
(American Astronomical Society, 2026) Jarvis, Matthew; Mentuch Cooper, Erin; Gebhardt, Karl
The Hobby–Eberly Telescope Dark Energy Experiment (HETDEX) is a wide-field, integral-field spectroscopic survey designed to map the large-scale distribution of Lyα-emitting galaxies (LAEs) at 1.88 < z < 3.52 and constrain dark energy at cosmic noon. Using the 10 m Hobby–Eberly Telescope and the Visible Integral-Field Replicable Unit (IFU) Spectrograph, HETDEX obtains >35,000 spectra per exposure over 3500–5500 Å at R ∼ 800 with (Formula presented) ∼1.″8 image quality, enabling an untargeted census of emission-line galaxies across 540 deg2. We present HETDEX Public Data Release 1 (PDR1), comprising 431,713 IFU observations covering 86.67 deg2 of noncontiguous sky in the Spring (13h, +51°) and Fall (1 (Formula presented) .h 5, 0°) fields, along with legacy regions (Cosmic Evolution Survey, Great Observations Origins Deep Survey North, North Ecliptic Pole, SA22). PDR1 includes the HETDEX Public Source Catalog 2 (HPSC2), an expanded and reprocessed version of E. Mentuch Cooper et al. (2023) incorporating four additional years of data, improved quality control, and new machine learning classifiers. HPSC2 contains 426,654 LAEs, 491,411 [O II] emitters, 19,457 low-z galaxies, 18,303 active galactic nuclei, and 150,608 stars, providing coordinates, redshifts or stellar velocities, and 1D spectra for each source. Because the data cubes use local sky subtraction optimized for faint emission-line detection, they are not suited for absolute surface-brightness measurements or very extended nearby galaxies. Appendix materials include the full detection catalog, the 1.6 million–candidate LAE sample, and raw detection databases. All products are publicly accessible through the HETDEX data portal (https://hetdex.org/data-results/), including access to a public JupyterLab. HPSC2 is also publicly available via Zenodo (doi:10.5281/zenodo.19581262).
Euclid preparation: LXXXIV. The flat-sky approximation for the clustering of euclids photometric galaxies
(EDP Sciences, 2026) Matthewson W.L.; Durrer R.; Camera S.; Tutusaus I.
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.
Collectivity of the deformed structure in 96zr from complementary coulomb-excitation and β-decay measurements
(Elsevier B.V., 2026-06) Maqungo L.; Triambak S.; Garrett P.E.; Zielińska M.; Rocchini M.
The B(E2;22+→01+) value in 96Zr was determined from a Coulomb-excitation measurement with 12C and 16O beams performed at the Maier-Leibnitz Laboratory with a Q3D magnetic spectrograph. High-precision γ -ray branching ratios in the decay of the 22+ state in 96Zr, and a new value of the 22+→21+ multipole mixing ratio, were obtained from a complementary β -decay experiment, performed using the GRIFFIN spectrometer at the TRIUMF-ISAC facility. Combining these results yields B(E2;22+→02+)=38.9(57) W.u. which is in agreement with the previous measurement, but considerably more precise. The observed differences between the properties of structures built on the 02+ states in 94Zr and 96Zr are discussed in the context of possible triple shape coexistence in Zr nuclei.
Euclid preparation: LXXXIII. the impact of redshift interlopers on the two-point correlation function analysis
(EDP Sciences, 2026) Karagiannis, Dionysics; Risso I.; Veropalumbo A.
Context. The Euclid galaxy survey is designed to measure the spectroscopic redshift of emission-line galaxies (ELGs) by identifying the Hα emission line in their slitless spectra. The efficacy of this approach crucially depends on the signal-to-noise ratio (S/N) of the line, as sometimes noise fluctuations in the spectrum continuum can be misidentified as Hα. In addition, other genuine strong emission lines can be mistaken for Hα, depending on the redshift of the source. Both effects lead to ambiguities in the redshift measurement that can result in catastrophic redshift errors and the inclusion of interloper galaxies in the sample. Aims. This paper forecasts the impact on the galaxy clustering analysis of the expected redshift errors in the Euclid spectroscopic sample. Specifically, it investigates the effect of the redshift interloper contamination on the galaxy two-point correlation function (2PCF) and, in turn, on the inferred growth rate of structure f8 and Alcock Paczynski (AP) parameters α and α. Methods. This work is based on the analysis of 1000 synthetic spectroscopic catalogues, the EuclidLargeMocks, which mimic the area and selection function of the Euclid Data Release 1 (DR1) sample. We estimated the 2PCF of contaminated catalogues and separated the different contributions, particularly those coming from galaxies with correctly measured redshift and from contaminants. We explored different models of increasing complexity to describe the measured 2PCF at a fixed cosmology, with the aim of identifying the most efficient model to reproduce the data. Finally, we performed a cosmological inference and evaluated the systematic error on the inferred f8, α, and α values associated with different models. Results. Our results demonstrate that a minimal modelling approach, which only accounts for an attenuation of the clustering signal regardless of the type of contaminants, is sufficient to recover the correct values of f8, α, and α at DR1. The accuracy and precision of the estimated AP parameters are largely insensitive to the presence of interlopers. The adoption of a minimal modelling induces a 1% 3% systematic error on the growth rate of structure estimation, depending on the considered redshift. However, this error remains smaller than the statistical error expected for the Euclid DR1 analysis.
Euclid: searches for strong gravitational lenses using convolutional neural nets in early release observations of the perseus field
(EDP Sciences, 2025) Pearce-Casey R.; Vaccari, M; Nagam B.C.
The Euclid Wide Survey (EWS) is predicted to find approximately 170 000 galaxy-galaxy strong lenses from its lifetime observation of 14 000 deg2 of the sky. Detecting this many lenses by visual inspection with professional astronomers and citizen scientists alone is infeasible. As a result, machine learning algorithms, particularly convolutional neural networks (CNNs), have been used as an automated method of detecting strong lenses, and have proven fruitful in finding galaxy-galaxy strong lens candidates, such that the usage of CNNs in lens identification has increased. We identify the major challenge to be the automatic detection of galaxy-galaxy strong lenses while simultaneously maintaining a low false positive rate, thus producing a pure and complete sample of strong lens candidates from Euclid with a limited need for visual inspection. One aim of this research is to have a quantified starting point on the achieved purity and completeness with our current version of CNN-based detection pipelines for the VIS images of EWS. This work is vital in preparing our CNN-based detection pipelines to be able to produce a pure sample of the >100 000 strong gravitational lensing systems widely predicted for Euclid. We select all sources with VIS IE < 23 mag from the Euclid Early Release Observation imaging of the Perseus field. We apply a range of CNN architectures to detect strong lenses in these cutouts. All our networks perform extremely well on simulated data sets and their respective validation sets. However, when applied to real Euclid imaging, the highest lens purity is just ∼11%. Among all our networks, the false positives are typically identifiable by human volunteers as, for example, spiral galaxies, multiple sources, and artifacts, implying that improvements are still possible, perhaps via a second, more interpretable lens selection filtering stage. There is currently no alternative to human classification of CNN-selected lens candidates. Given the expected ∼105 lensing systems in Euclid, this implies 106 objects for human classification, which while very large is not in principle intractable and not without precedent.
Multipoles of the galaxy bispectrum on a light cone: wide-separation and relativistic corrections
(Institute of Physics, 2025) Addis, Chris; Clarkson, Chris; Guandalin, Caroline
The galaxy bispectrum provides access to correlations among different scales that cannot be captured by the power spectrum alone, and with the Stage-IV galaxy surveys it enables the possibility of detecting both primordial non-Gaussianity (PNG) and general relativistic effects. Accounting for wide-separation corrections, which arise from the loss of symmetry in the correlation of widely separated points on the past light cone, is essential for their accurate modelling and detection. These corrections can be included perturbatively to the standard bispectrum and we compute them analytically for a generalised line of sight, including the radial evolution contribution to the bispectrum for the first time. We show that the first-order corrections entering the odd multipoles with respect to the line of sight are large, up to 10% of the bispectrum monopole, and need to be included when considering the leading-order relativistic effects that could be detectable with surveys like DESI and Euclid. The second-order wide-separation and relativistic contributions, including their mixing terms, enter into the even multipoles and therefore have implications for analysis of PNG and we show, for the local type, they can mimic fNL of order 10 in the squeezed limit. We present full analytic expressions for all these contributions to the local bispectrum and its multipoles which are implemented in a new publicly available Python package CosmoWAP.
Toward reconciling reionization with jwst: the role of bright galaxies and strong feedback
(American Astronomical Society, 2026) Bera, Ankita; Hassan, Sultan; Feldmann, Robert; Dav́e, Romeel; Finlator, Kristian M.
The elevated UV luminosity functions (UVLFs) from recent James Webb Space Telescope (JWST) observations have challenged the viability of existing theoretical models. To address this, we use a semianalytical framework—which couples a physically motivated source model derived from radiative transfer hydrodynamic simulations of reionization with a Markov Chain Monte Carlo sampler—to perform a joint calibration to JWST galaxy surveys (UVLF, ϕUV, and UV luminosity density, ρUV) and reionization-era observables (ionizing emissivity, (Formula presented) Ṅion, neutral hydrogen fraction, xHI, and Thomson optical depth, τ). We find that models with weak feedback and a higher contribution from faint galaxies reproduce the reionization observables but struggle to match the elevated JWST UVLF at z > 9. In contrast, models with stronger feedback (i.e., rapid redshift evolution) and a higher contribution from bright galaxies successfully reproduce JWST UVLF at z ≥ 10 but overestimate the bright end at z < 9. The strong-feedback model constrained by the JWST UVLF predicts a more gradual and extended reionization history, as opposed to the sudden reionization seen in the weak-feedback models. This extended nature of reionization (z ∼ 16–6) yields an optical depth consistent (at 2σ) with the cosmic microwave background (CMB) constraint, thereby alleviating the photon budget crisis. In both scenarios, reionization is complete by z ∼ 6, consistent with current data. Our analysis highlights the importance of accurately modeling feedback and ionizing emissivities from different source populations during the first billion years after the Big Bang.
Uniform rolling: an LSST observing cadence offering sufficient survey uniformity for comprehensive cosmological analysis
(American Astronomical Society, 2026) Lochner, Michelle; Leistedt, Boris; Becker, Matthew
The Legacy Survey of Space and Time (LSST) that will be carried out by the NSF-DOE Vera C. Rubin Observatory promises to be the defining survey of the next decade for both static and time-domain science. Maximizing the LSST’s scientific output requires a nontrivial survey strategy (i.e., the sequence of observations in space, time, and passband). For time-domain science, the most promising strategy to date is a rolling survey strategy, whereby alternating subsets of the full LSST area are observed at a higher-than-nominal rate. Focusing on static science (galaxy clustering and weak lensing), we study how time-domain-optimized rolling strategies affect the depth uniformity at intermediate survey years and present new metrics directly connecting depth uniformity with science return. We characterize the amount of survey area at high risk of being lost in static-science analyses of a rolling LSST data set due to insufficient survey uniformity. At intermediate data releases, nearly half of the survey could be lost for static science, decreasing the dark energy figure of merit by 40%. We describe additional metrics focused on key analysis tasks, such as photometric redshifts and galaxy clustering. Finally, we propose a new strategy that returns the survey to uniformity at key release years, enabling use of the full area and restoring our metrics to the values they would have in a nonrolling cadence—without losing time domain data relative to a rolling survey with the same number of rolling cycles. These new “uniform rolling” strategies have been incorporated into the LSST baseline strategy.
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.
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.
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.
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.
Identification of the pygmy dipole resonance in a well deformed nucleus by combined isoscalar and isovector probes
(Elsevier B.V., 2026) Marín-Lámbarri, Daniel José; Mukwevho, Ndinannyi Justice; Pesudo, Vicente; Rebeiro, Bernadette; Triambak, Smarajit
The low-energy electric dipole response in the axially deformed 154Sm nucleus was investigated for the first time using complementary probes. The isoscalar (IS) response was extracted from an ( α, α ′ γ ) coincidence experiment and the isovector (IV) response from polarization observables measured with the (p→,p→′) reaction at 0∘. Both the IS and IV responses exhibit a resonance-like structure at excitation energies 5.5-6 MeV identified as the pygmy dipole resonance. Its evolution with deformation is investigated by comparison to the spherical isotope 144Sm. The low-energy IV strength in 154Sm departs from the K -splitting picture that characterizes the IV giant dipole resonance in this nucleus. This finding is further supported by the absence of significant IS strength above 7 MeV.
Euclid preparation: LXXXI. The impact of nonparametric star formation histories on spatially resolved galaxy property estimation using synthetic Euclid images
(EDP Sciences, 2026) Karagiannis, Dionysios; Nersesian A.; Abdurro'uf
Aims. We analyzed the spatially resolved and global star formation histories (SFHs) for a sample of 25 TNG50-SKIRT Atlas galaxies to assess the feasibility of reconstructing accurate SFHs from Euclid-like data. This study provides a proof of concept for extracting the spatially resolved SFHs of local galaxies with Euclid, highlighting the strengths and limitations of SFH modeling in the context of next-generation galaxy surveys. Methods. We used the spectral energy distribution (SED) fitting code Prospector to model both spatially resolved and global SFHs using parametric and nonparametric configurations. The input consisted of mock ultraviolet near-infrared photometry derived from the TNG50 cosmological simulation and processed with the radiative transfer code SKIRT. Results. We show that nonparametric SFHs provide a more effective approach to mitigating the outshining effect by recent star formation, offering improved accuracy in the determination of galaxy stellar properties. Also, we find that the nonparametric SFH model at resolved scales closely recovers the stellar mass formation times (within 0.1 dex) and the ground truth values from TNG50, with an absolute average bias of 0.03 dex in stellar mass and 0.01 dex in both specific star formation rate and mass-weighted age. In contrast, larger offsets are estimated for all stellar properties and formation times when using a simple -model SFH, at both resolved and global scales, highlighting its limitations. Conclusions. These results emphasize the critical role of nonparametric SFHs in both global and spatially resolved analyses, as they better capture the complex evolutionary pathways of galaxies and avoid the biases inherent in simple parametric models.
Exploring the quasar disc–wind–jet connection with LoTSS and SDSS
(Oxford University Press, 2026) Whittam, Imogen H.; Jackson, Charlotte L.; Jarvis, Matt J.
We investigate the relationship between disc winds, radio jets, accretion rates, and black hole masses of a sample of ∼100 k quasars at z ≈2. Combining spectra from the 17th data release of the Sloan Digital Sky Survey (SDSS) with radio fluxes from the 2nd data release of the Low F requency ARr ay (LOFAR) Tw o-Met er Sky Surv ey (LoTSS), w e statistically charact erize a radio-loud and radio - quiet population using a two - component Gaussian Mixture model, and perform population matching in black hole mass and Eddingt on fraction. We det ermine how the fr action of r adio-loud sources changes across this parameter space, finding that jets are most efficiently produced in quasars with either a very massive central black hole( MBH > 109 M ) or one that is rapidly accreting ( λEdd > 0 . 3 ). We also show that there are differences in the blueshift of the C iv λ 1549 Åline and the equivalent width of the He ii λ1640 Åline in radio loud and radio - quiet quasars that persist even after accounting for differences in the mass and accretion rate of the central black hole. Generally, we find an anticorrelation between the inferred presence of disc winds and jets, which we suggest is mediated by differences in the quasars’ spectral energy distributions. The latter result is shown through the close coupling between tracers of wind kinematics and the ionizing flux – which holds for both radio-loud and radio - quiet sources, despite differences between their emission line properties –and is hinted at by a different Baldwin effect in the two populations.
Weakly supervised anomaly detection for resonant new physics in the dijet final state using proton-proton collisions at (Formula presented.) with the ATLAS detector
(American Physical Society, 2026) Leeuw, Lerothodi.L; Aad G.; Aakvaag E.
An anomaly detection search for narrow-width resonances beyond the Standard Model that decay into a pair of jets is presented. The search is based on 139 fb−1 of proton-proton collisions at (Formula presented.) recorded during 2015–2018 with the ATLAS detector at the Large Hadron Collider. The analysis is optimized without a particular signal model and aims to be sensitive to a broad range of new physics. It uses two different machine learning strategies to estimate the background in different signal regions. In each region, a weakly supervised classifier is trained to distinguish this background model from data. The analysis focuses on events with high transverse momentum jets reconstructed as large-radius jets. The mass and substructure of these jets are used as inputs to the classifiers. After a classifier-based selection, the distribution of the invariant mass of the two jets is used to search for potential local excesses. The model-independent results of both the anomaly detection methods show no signs of significant local excesses. In addition to model-independent results, a representative set of signal models is injected into the data, and the sensitivity of the methods to these scenarios is reported.

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