Philip C. Schouten; Melis O Irfan; Zak Kinsella; Aristeidis Sionakidis; Amy Riddell; Joanna R. Worley; Jonny Lay; Sam Casford; Karen Pinilla; Justine Kane; Deborah Whitehorn; Silvia Tarantino; Alimu Dayimu; Nikos Demiris; Helena M Earl; Nikola Simidjievski; Elena Provenzano; Jean E Abraham
medRxiv · DOI ↗
Assessment of tumour infiltrating lymphocytes (TILs) is a robust prognostic biomarker for HER2-positive and triple negative breast cancer. We aimed to update a previously established pipeline for automated TIL assessment to align to clinical scoring guidelines (tumour region identification guided scoring), foundation model-based lymphocyte detection (SAM-TIL) and compare with alternative methods (HoVerNet, muTILs) and gold standard clinical assessment. TRIGS and SAM-TIL had an odds ratio of 1.95 (95% confidence interval(ci): 1.22-3.03, p=0.005) and 2.32 (95% ci:1.43-3.77, p=0.001) for predicting pathological complete response (pCR) rate in 166 neoadjuvantly treated patients in the TransNEO cohort. Hazard ratios for overall survival in 277 triple negative and HER2-positive patients in The Cancer Genome Atlas were 0.79 (95% ci: 0.63-1.00, p=0.05) and 0.80 (95% ci: 0.67-0.97, p=0.02) for TRIGS and SAM-TIL. Comparator methods showed similar results. Correlation with gold standard clinical assessment in 285 patients from the PARTNER randomized trial ranged from 0.59-0.69, which is substantially more than interobserver variability for the gold standard. Despite differences with gold standard assessment, no substantial difference in predicting pCR (AUC 0.60-0.64) or event free survival (Integrated Brier score approximately 0.10) were observed between the tested methods and gold standard assessment, suggesting AI tools that do not follow manual scoring guidelines could be validated and subsequently used. Although we reached prognostic performance similar to published literature and gold standard assessment, the lymphocyte detections produced by the models are not interchangeable with gold standard clinical assessment (correlation 0.59-0.69) and therefore cannot support pathologist assessment. Further studies to validate independent use and/or to improve prognostication are required.
L. Venuti; Ann Marie Cody; G. Beccari; M. J. Irwin; J. E. Drew
Zenodo (CERN European Organization for Nuclear Research) · DOI ↗
Collection of VST/OmegaCAM light curve files for all young stellar objects in the Lagoon Nebula region that have been identified as members or candidate members in Table 1 of Venuti et al. (2024, AJ, 167, 120). These photometric time series were obtained in 2016 (program id 297.C-5033(A)), reduced as described in Venuti et al. (2021, AJ, 162, 101), and analyzed in Venuti et al. (2024). Individual sources are matched to the corresponding datafiles by their identifier, as listed in the first column of Table 1 in Venuti et al. (2024) and in the datafile name. Each datafile, in .txt format, contains four columns: Modified Julian Date, magnitude, magnitude uncertainty, and filter (u/g/r/i/Ha). All magnitudes have been calibrated to the VPHAS+ survey catalog (Drew et al. 2014, MNRAS, 440, 2036).
L. Venuti; Ann Marie Cody; G. Beccari; M. J. Irwin; J. E. Drew
Zenodo (CERN European Organization for Nuclear Research) · DOI ↗
Collection of VST/OmegaCAM light curve files for all young stellar objects in the Lagoon Nebula region that have been identified as members or candidate members in Table 1 of Venuti et al. (2024, AJ, 167, 120). These photometric time series were obtained in 2016 (program id 297.C-5033(A)), reduced as described in Venuti et al. (2021, AJ, 162, 101), and analyzed in Venuti et al. (2024). Individual sources are matched to the corresponding datafiles by their identifier, as listed in the first column of Table 1 in Venuti et al. (2024) and in the datafile name. Each datafile, in .txt format, contains four columns: Modified Julian Date, magnitude, magnitude uncertainty, and filter (u/g/r/i/Ha). All magnitudes have been calibrated to the VPHAS+ survey catalog (Drew et al. 2014, MNRAS, 440, 2036).
Ian Selby; E. González-Solares; Anna Breger; Michael Roberts; L. Escudero; Judith Babar; James H.F. Rudd; N. A. Walton; Evis Sala; Carola‐Bibiane Schönlieb; Jonathan Weir‐McCall; Michael Roberts; Sören Dittmer; Ian Selby; Anna Breger; Matthew Thorpe; Julian Gilbey; Jonathan Weir‐McCall; Judith Babar; Effrossyni Gkrania‐Klotsas; Jacobus Preller; Lorena Escudero Sánchez; Andrew N. Priest; Anna Korhonen; Emily Jefferson; Georg Langs; Helmut Prosch; Martin J. Graves; Guang Yang; Xiaodan Xing; Nan Yang; Ming Li; Jan Stanczuk; Jing Tang; Tolou Shadbahr; Philip Teare; Mishal Patel; Marcel Wassink; Markus Holzer; E. González-Solares; Nicholas Walton; Píetro Lió; James H.F. Rudd; John A. D. Aston; Evis Sala; Carola‐Bibiane Schönlieb
Radiology Artificial Intelligence · DOI ↗
This article presents a suite of quality control tools for chest radiographs based on traditional and artificial intelligence methods, developed and tested with data from 39 centers in seven countries.
Michael J. Wilensky; Melis O Irfan; Philip Bull
Monthly Notices of the Royal Astronomical Society · DOI ↗
ABSTRACT The 408 MHz Haslam map is widely used as a low-frequency anchor for the intensity and morphology of Galactic synchrotron emission. Multifrequency, multi-experiment fits show evidence of spatial variation and curvature in the synchrotron frequency spectrum, but there are also poorly understood multiplicative flux scale disagreements between experiments. We perform a Bayesian model comparison across a range of scenarios, using fits that include recent spectroscopic observations at $\sim 1$ GHz by MeerKAT as well as a reference map from the Owens Valley Radio Observatory Long Wavelength Array (OVRO-LWA) at 73 MHz. In the few square degrees that we analysed, a large uncorrected flux scale factor potentially as large as 1.6 in the Haslam data is preferred, indicating a 60 per cent overestimation of the brightness. This partly undermines its use as a reference map. We also find that models with non-zero spectral curvature are statistically disfavoured. Given the limited sky coverage here, we suggest a similar analysis across many more regions of the sky to determine the extent and variation of flux scale errors, and whether they should be treated as random or systematic errors in analyses that use the Haslam map as a template.
Thomas A Baycroft; A. Santerne; A. H. M. J. Triaud; N. Heidari; Daniel Sebastian; Yasmin Davis; A. C. M. Correia; S. Lalitha; Alix Violet Freckelton; Aleyna Adamson; Isabelle Boisse; Gavin A. L. Coleman; Georgina Dransfield; J. P. Faria; S. Grouffal; N. Hara; Guillaume Hébrard; Vedad Kunovac; David V. Martin; P. F. L. Maxted; Richard P. Nelson; M. G. Scott; Owen J Scutt; Matthew R. Standing
Monthly Notices of the Royal Astronomical Society · DOI ↗
ABSTRACT Planetary systems orbiting close binaries are valuable testing grounds for planet formation and migration models. More detections with good mass measurements are needed. We present a new planet discovered during the BEBOP survey for circumbinary exoplanets using radial velocities. We use data taken with the SOPHIE spectrograph at the Observatoire de Haute-Provence, and perform a spectroscopic analysis to obtain high precision radial velocities. This planet is the first radial velocity detection of a previously unknown circumbinary system. The planet has a mass of 0.56 $\rm M_{Jup}$ and orbits its host binary in 550 d with an eccentricity of 0.25. Compared to most of the previously known circumbinary planets, BEBOP-3b has a long period (relative to the binary) and a high eccentricity. There also is a candidate outer planet with a $\sim 1400$ d orbital period. We test the stability of potential further candidate signals inside the orbit of BEBOP-3b, and demonstrate that there are stable orbital solutions for planets near the instability region which is where the Kepler circumbinary planets are located. We also use our data to obtain independent dynamical masses for the two stellar components of the eclipsing binary using high resolution cross-correlation spectroscopy, and compare those results to a more traditional approach, finding them compatible with one another.
Dario Bressan; N. A. Walton; Gregory J. Hannon; Mohammad Al Sa’d; Bruno Albuquerque; Hamid Raza Ali; Martina Alini; Samuel Aparício; Heather Ashmore; Thomas J. Ashmore; et al.
Cancer Discovery · DOI ↗
The Imaging and Molecular Annotation of Xenografts and Tumors Cancer Grand Challenges team was set up with the objective of developing the "next generation" of pathology and cancer research by using a combination of single-cell and spatial omics tools to produce 3D molecularly annotated maps of tumors. Its activities overlapped, and in some cases catalyzed, a spatial revolution in biology that saw new technologies being deployed to investigate the roles of tumor heterogeneity and of the tumor micro-environment. See related article by Stratton et al., p. 22 See related article by Bhattacharjee et al., p. 28 See related article by Goodwin et al., p. 34.
Leigh C. Smith; Saad Ahmed; F. De Angeli; P. W. Burgess; G. Busso; Dominic Ford; D. L. Harrison; S. T. Hodgkin; Jonathan Irwin; Guy Rixon; N. A. Walton
Monthly Notices of the Royal Astronomical Society · DOI ↗
ABSTRACT We present the Cambridge Exoplanet Transit Recovery Algorithm (cetra), a fast and sensitive transit detection algorithm, optimized for GPUs. cetra separates the task into a search for transit signals across linear time space, followed by a phase-folding of the former to enable a periodic signal search, using a physically motivated transit model to improve detection sensitivity. It outperforms traditional methods like Box Least Squares and Transit Least Squares in both sensitivity and speed. Tests on synthetic light curves demonstrate that cetra can identify at least 20 per cent more low-SNR transits than Transit Least Squares in the same data, particularly those of long period planets. It is also shown to be up to a few orders of magnitude faster for high cadence light curves, enabling rapid large-scale searches. Through application of cetra to Transiting Exoplanet Survey Satellite short cadence data, we recover the three planets in the HD 101581 system with improved significance. In particular, the transit signal of the previously unvalidated planet TOI-6276.03 is enhanced from ${\rm SNR}=7.9$ to ${\rm SNR}=16.0$, which means it may now meet the criteria for statistical validation. cetra’s speed and sensitivity make it well-suited for current and future exoplanet surveys, particularly in the search for Earth analogues. Our implementation of this algorithm uses NVIDIA’s CUDA platform and requires an NVIDIA GPU, it is open-source and available from GitHub and PyPI.
S. Lalitha; Nikku Madhusudhan
Monthly Notices of the Royal Astronomical Society · DOI ↗
ABSTRACT Planetary systems orbiting M dwarf host stars are promising targets for atmospheric characterization of low-mass exoplanets. Accurate characterization of M dwarf hosts is important for detailed understanding of the planetary properties and physical processes, including potential habitability. Recent studies have identified several candidate Hycean planets orbiting nearby M dwarfs as promising targets in the search for habitability and life on exoplanets. In this study, we characterize two such M dwarf host stars, K2-18 and TOI-732. Using archival photometric and spectroscopic observations, we estimate their effective temperatures ($T_{\mathrm{eff}}$) and metallicities through high-resolution spectral analyses and ages through gyrochronology. We assess the stellar activity of the targets by analysing activity-sensitive chromospheric lines and X-ray luminosities. Additionally, we predict activity cycles based on measured rotation periods and utilize photometric data to estimate the current stellar activity phase. We find K2-18 to be 2.9–3.1 Gyr old with $T_{\mathrm{eff}}$ = 3645 $\pm$ 52 K and metallicity of [Fe/H] = 0.10 $\pm$ 0.12 dex, and TOI-732 to be older (6.7–8.6 Gyr), cooler (3213 $\pm$ 92 K), and more metal-rich ([Fe/H] = 0.22 $\pm$ 0.13 dex). Both stars exhibit relatively low activity making them favourable for atmospheric observations of their planets. The predicted activity cycle and analysis of available high-precision photometry for K2-18 suggest that it might have been near an activity minimum during recent JWST observations, though some residual activity may be expected at such minima. We predict potential activity levels for both targets to aid future observations and highlight the importance of accurate characterization of M dwarf host stars for exoplanet characterization.
Tristan Whitmarsh
JBMR Plus · DOI ↗
3D-DXA, as implemented in the software tool 3D-Shaper, is a software method that generates a 3D reconstruction of the proximal femur from a single 2D DXA image by registering a statistical model. Implementations of 3D-DXA aim to provide estimates of trabecular, cortical, and structural parameters, similar to those derived from quantitative computed tomography (QCT). As the inventor and developer of the software methods upon which 3D-DXA is built, I have been observing its adoption and widespread use with increasing concern. This article provides a critical evaluation of the methodological limitations inherent to 3D-DXA and discusses their implications for research and patient care. The primary issue is that the limited visibility of the cortex in a DXA image prevents 3D-DXA from accurately deriving cortical parameters. Instead, the software relies on predictions based on overall BMD rather than direct cortical measurements. This may lead to results that do not reflect actual cortical measurements. Additional concerns include the population bias due to the statistical model being derived from a specific demographic, and limited reconstruction accuracy by using single-view DXA images. These limitations have likely resulted in incorrect measurements and research outcomes, which have largely gone unrecognized due to the use of inappropriate performance assessment metrics and the absence of multiple comparison corrections in studies involving 3D-DXA. Despite these limitations, 3D-DXA has received regulatory approval in various countries, potentially compromising the accuracy of clinical diagnoses and treatment decisions. By highlighting these issues, this article aims to inform clinicians, researchers, and regulatory bodies about the significant limitations of 3D-DXA. It underscores the urgent need for a reevaluation of its use in research and clinical settings to prevent misinterpretation of results and to ensure patient safety.
Thomas A Baycroft; S. Lalitha; A. H. M. J. Triaud; A. C. M. Correia
Science Advances · DOI ↗
One notable example of exoplanet diversity is the population of circumbinary planets, which orbit around both stars of a binary star system. There are, so far, only 16 known circumbinary exoplanets, all of which lie in the same orbital plane as the host binary. Suggestions indicate that circumbinary planets could also exist on orbits highly inclined to the binary, close to 90°, polar orbits. No such planets have been found yet, but polar circumbinary gas and debris discs have been observed, and if these were to form planets, then those would be left on a polar orbit. We report strong evidence for a polar circumbinary exoplanet, which orbits a close pair of brown dwarfs that are on an eccentric orbit. We use radial velocities to measure a retrograde apsidal precession for the binary and show that this can only be attributed to the presence of a polar planet.
Michael J. Wilensky; Melis O Irfan; Philip Bull
Accurate models of Galactic synchrotron emission are critical for our understanding of astrophysics and cosmology. For example, this emission is a bright foreground in observations of the redshifted 21-cm line and the Cosmic Microwave Background. It also serves as a probe of the astrophysical properties of our Galaxy such as its magnetic field. Galactic synchrotron emission is often modeled by anchoring to the 408 MHz Haslam map. While the map has been extensively analyzed over the past few decades and several of its known issues have been corrected, there are still uncertainties regarding the absolute calibration of the flux scale that are made apparent when compared to other maps of diffuse radio emission.
G. Riccio; Michele Cantiello; Rebecca Habas; Nandini Hazra; G. D’Ago; Gabriella Raimondo; John P. Blakeslee; Joseph B. Jensen; Marco Mirabile; E. Brocato; M. Brescia; C. M. Raiteri
Astronomy and Astrophysics · DOI ↗
Context. The surface brightness fluctuation (SBF) method is one of the most reliable and efficient ways of measuring distances to galaxies within 100 Mpc, a matter of crucial importance for all fields of astrophysics. While recent implementations have increasingly relied on space-based observations, SBF remains effective when applied to ground-based data. In particular, deep, wide-field imaging surveys with sub-arcsecond seeing conditions allows us to make accurate SBF measurements across large samples of galaxies. With the upcoming next generation of wide-area imaging surveys, the thousands of galaxies suitable for SBF measurements will give us the opportunity to constrain the 3D structure of the local Universe. Aims. We present FAST-SBF, a new Python-based pipeline for measuring SBF, developed to support the analysis of large datasets from upcoming wide-field imaging surveys such as LSST, Euclid , and Roman . The procedure, still in the testing and development stage, is designed for automation and minimal user intervention, offering a fast and flexible approach to SBF distance estimation. Methods. We validated the performance of the procedure on high-quality imaging data from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP), a precursor to LSST, analyzing a sample of both luminous early-type galaxies and fainter dwarfs. Our measurements were also compared with recent results from the Next Generation Virgo Cluster Survey (NGVS) and with the SPoT stellar population synthesis models. Results. The results show excellent agreement with published distances, with the capability of measuring the SBF signal also for faint dwarf galaxies. The pipeline allows the user to completely analyze a galaxy in relatively short time (≈ minutes) and significantly reduces the need for user intervention. The FAST-SBF tool is planned for public release to support the community in using SBF as a distance indicator in next-generation surveys.
Isabella P. Carucci; José L Bernal; Steven Cunnington; Mário G. Santos; Jingying Wang; José Fonseca; Keith Grainge; Melis O Irfan; Yichao Li; Alkistis Pourtsidou; Marta Spinelli; Laura Wolz
Astronomy and Astrophysics · DOI ↗
Removing contaminants is a delicate, yet crucial step in neutral hydrogen (H I ) intensity mapping and often considered the technique’s greatest challenge. Here, we address this challenge by analysing H I intensity maps of about 100 deg 2 at redshift z ≈ 0.4 collected by the MeerKAT radio telescope, an SKA Observatory (SKAO) precursor, with a combined 10.5-hour observation. Using unsupervised statistical methods, we removed the contaminating foreground emission and systematically tested, step-by-step, some common pre-processing choices to facilitate the cleaning process. We also introduced and tested a novel multiscale approach: the data were redundantly decomposed into subsets referring to different spatial scales (large and small), where the cleaning procedure was performed independently. We confirm the detection of the H I cosmological signal in cross-correlation with an ancillary galactic data set, without the need to correct for signal loss. In the best set-up we achieved, we were able to constrain the H I distribution through the combination of its cosmic abundance (Ω H I ) and linear clustering bias ( b H I ) up to a cross-correlation coefficient ( r ). We measured Ω H I b H I r = [0.93 ± 0.17] × 10 −3 with a ≈6 σ confidence, which is independent of scale cuts at both edges of the probed scale range (0.04 ≲ k ≲ 0.3 h Mpc −1 ), corroborating its robustness. Our new pipeline has successfully found an optimal compromise in separating contaminants without incurring a catastrophic signal loss. This development instills an added degree of confidence in the outstanding science we can deliver with MeerKAT on the path towards H I intensity mapping surveys with the full SKAO.
Ian Selby; E. González-Solares; Anna Breger; Michael Roberts; Lorena Escudero Sánchez; James H.F. Rudd; Nicholas Walton; Judith Babar; Carola‐Bibiane Schönlieb; Evis Sala; Jonathan Weir‐McCall
The Royal College of Radiologists Open · DOI ↗
C. Tortora; G. Tozzi; Guido Agapito; F. La Barbera; Chiara Spiniello; Rui Li; Giulia Carlà; G. D’Ago; Essna Ghose; F. Mannucci; N. R. Napolitano; Enrico Pinna; M. Arnaboldi; Davide Bevacqua; Anna Ferré-Mateu; Anna Gallazzi; Johanna Hartke; L. K. Hunt; Michalina Maksymowicz-Maciata; C. Pulsoni; P. Saracco; Diana Scognamiglio; Marilena Spavone
Monthly Notices of the Royal Astronomical Society · DOI ↗
ABSTRACT Relics are massive, compact and quiescent galaxies that assembled the majority of their stars in the early Universe and lived untouched until today, completely missing any subsequent size growth caused by mergers and interactions. They provide the unique opportunity to put constraints on the first phase of mass assembly in the Universe with the ease of being nearby. While only a few relics have been found in the local Universe, the INSPIRE project has confirmed 38 relics at higher redshifts ($z \sim 0.2{\small --}0.4$), fully characterizing their integrated kinematics and stellar populations. However, given the very small sizes of these objects and the limitations imposed by the atmosphere, structural parameters inferred from ground-based optical imaging are possibly affected by systematic effects that are difficult to quantify. In this paper, we present the first high-resolution image obtained with Adaptive Optics Ks-band observations on SOUL-LUCI@LBT of one of the most extreme INSPIRE relics, KiDS J0842 + 0059 at $z \sim 0.3$. We confirm the discy morphology of this galaxy (axis ratio of 0.24) and its compact nature (circularized effective radius of $\sim 1$ kpc) by modelling its 2D surface brightness profile with a point-spread function-convolved Sérsic model. We demonstrate that the surface mass density profile of KiDS J0842 + 0059 closely resembles that of the most extreme local relic, NGC 1277, as well as of high-redshift red nuggets. We unambiguously conclude that this object is a remnant of a high-redshift compact and massive galaxy, which assembled all of its mass at $z>2$, and completely missed the merger phase of the galaxy evolution at high redshift.
Charles Yin; A. Lawrence; M. J. Ward; D. Homan; W. Kollatschny
Monthly Notices of the Royal Astronomical Society · DOI ↗
ABSTRACT We present flux measurements of the coronal lines [Fe vii] and [Fe x] spanning three decades, in the highly variable active galactic nucleus (AGN) MKN 110. These coronal lines are sensitive to the spectral energy distribution of AGNs in the extreme ultraviolet. Neither [Fe vii] nor [Fe x] demonstrates variability in the short term on a weekly or monthly time-scale. However, by taking advantage of a long-term decrease in the continuum flux of MKN 110 of the order of years, we were able to track the [Fe vii] and [Fe x] fluxes as they respond to the continuum. We were able to detect a lag for [Fe vii] relative to the continuum at 5100 Å, with a modal lag of 652 d, but were unable to detect a significant lag in the [Fe x] flux, though there exist significant uncertainties in the [Fe x] fit. These two lag results are not consistent and the line widths for the two line species also do not match. This provides strong evidence for stratification within the coronal line region (CLR). There is also evidence of a non-varying component within the coronal line flux, probably a result of a more extended region of origin. Taken together, these results suggest a CLR where the bulk of the [Fe vii] originates on parsec scales, but a portion of the [Fe vii] flux originates further out, at or beyond a 10 pc scale. These results also indicate the limitations of single-cloud models in describing the physical conditions of the CLR.
Johanna Hartke; E. Iodice; M. Gullieuszik; Marco Mirabile; Chiara Buttitta; Goran Doll; G. D’Ago; C.C. de la Casa; Kelley M. Hess; Ralf Kotulla; Bianca M. Poggianti; M. Arnaboldi; M. Cantiello; E. M. Corsini; J. Falcón-Barroso; Duncan A. Forbes; M. Hilker; S. Mieske; M. Rejkuba; M. Spavone; C. Spiniello
Astronomy and Astrophysics · DOI ↗
Context. UDG 32 is an ultra-diffuse galaxy (UDG) candidate in the Hydra I cluster that was discovered in the extended network of stellar filaments of the jellyfish galaxy NGC 3314A. This jellyfish galaxy is affected by ram pressure stripping and it is hypothesised that UDG 32 may have formed from this stripped material. Aims. The aim of this paper is to address whether UDG 32 can be associated with the stripped material of NGC 3314A and to constrain its formation scenario in relation to its environment. Methods. We use new integral-field spectroscopic data from the MUSE large programme ‘LEWIS’ in conjunction with deep multi-band photometry to constrain the kinematics of UDG 32 via spectral fitting and its stellar population properties with spectral energy distribution fitting. Results. The new MUSE data allow us to reveal that the stripped material from NGC 3314A, traced by emission lines such as H α , extends much further from its parent galaxy than previously known, completely overlapping with UDG 32 in projection, and with ram pressure induced star formation. We determine the line-of-sight velocity of UDG 32 to be v LOS = 3080 ± 120 km s −1 and confirm that UDG 32 is part of the same kinematic structure as NGC 3314A, the Hydra I cluster south-east subgroup. By fitting the UV and optical spectral energy distribution obtained from deep multi-band photometry, we constrain the stellar population properties of UDG 32. We determine its mass-weighted age to be 7.7 −2.8 +2.9 Gyr and its metallicity to be [M/H] = 0.07 −0.32 +0.19 dex. We confirm the presence of two globular clusters (GCs) in the MUSE field of view, bound to the Hydra I cluster rather than to UDG 32, making them part of the Hydra I intracluster GC population. Conclusions. The metal-rich and intermediate-age nature of UDG 32 points towards its formation from pre-enriched material in the south-east group of the Hydra I cluster that was liberated from a more massive galaxy via tidal or ram-pressure stripping, but we cannot establish a direct link to the ram-pressure stripped material from NGC 3314A.
Nicholas Storm; Maria Bergemann; Tomasz Różański; Victor F. Ksoll; T. Bensby; G. Traven; Georges Kordopatis; Ross P. Church; Mingjie Jian; Weijia Sun; G. Guiglion; Gražina Tautvaišienė
Apollo (University of Cambridge)
We present the 4MOST-HR resolution non–local thermal equilibrium (NLTE) Payne artificial neural network (ANN), trained on 404,793 new FGK spectra with 16 elements computed in NLTE. This network will be part of the Stellar Abundances and atmospheric Parameters Pipeline (SAPP), which will analyze 4 million stars during the 5 yr long 4MOST consortium 4: 4MOST MIlky way Disc And BuLgE High-Resolution (4MIDABLE-HR) survey. A fitting algorithm using this ANN is also presented that is able to fully automatically and self-consistently derive both stellar parameters and elemental abundances. The ANN is validated by fitting 121 observed spectra of low-mass FGKM-type stars, including main-sequence dwarf, subgiant, and giant stars down to [Fe/H] ≈ −3.3 degraded to a 4MOST-HR resolution of R ≈ 20,000 and comparing the derived abundances with the output of the classical radiative transfer code TSFitPy. We are able to recover all 18 elemental abundances with a bias of <0.13 and spread of <0.16 dex, although the typical values are <0.09 dex for most elements. These abundances are compared to the OMEGA+ Galactic chemical evolution model, showcasing for the first time the expected performance and results obtained from high-resolution spectra of the quality expected to be obtained with 4MOST. The expected Galactic trends are recovered, and we highlight the potential of using many chemical elements to constrain the formation history of the Galaxy.
Rui Li; N. R. Napolitano; G. D’Ago; V. N. Shalyapin; Kai Zhu; Xiaotong Guo; Ran Li; L. V. E. Koopmans; Chiara Spiniello; C. Tortora; Francesco La Barbera; Hai-Cheng Feng; Liang Gao; Zhiqi Huang; Konrad Kuijken; Hui Li; L. Xie; M. Radovich; A. V. Sergeyev
The Astrophysical Journal Letters · DOI ↗
Abstract We report the spectroscopic confirmation of a bright blue Einstein ring in the Kilo-Degree Survey (KiDS) footprint: the Einstein “blue eye.” Spectroscopic data from X-Shooter at the Very Large Telescope (VLT) show that the lens is a typical early-type galaxy (ETG) at z l = 0.9906, while the background source is a Ly α emitter at z s = 2.823. The reference lens modeling was performed on a high-resolution Y- band adaptive-optics image from HAWK-I at VLT. Assuming a singular isothermal ellipsoid total mass density profile, we inferred an Einstein radius R Ein = 10.47 ± 0.06 kpc. The average slope of the total mass density inside the Einstein radius, as determined by a joint analysis of lensing and isotropic Jeans equations, is <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML&quot; overflow="scroll"> <mml:msub> <mml:mi>γ</mml:mi> <mml:mi>tot</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>2.1</mml:mn> <mml:msubsup> <mml:mn>4</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.07</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.06</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> , showing no systematic deviation from the slopes of lower-redshift galaxies. This can be the evidence of ETGs developing through dry mergers plus moderate dissipationless accretion. Stellar population analysis with eight-band ( gri ZYJHK s ) photometries from KiDS and VIKING shows that the total stellar mass of the lens is M * = (3.95 ± 0.35) × 10 11 M ⊙ (Salpeter initial mass function (IMF)), implying a dark matter fraction inside the effective radius of f DM = 0.307 ± 0.151. We finally explored the dark matter halo slope and found a strong degeneracy with the dynamic stellar mass. Dark matter adiabatic contraction is needed to explain the posterior distribution of the slope, unless an IMF heavier than Salpeter is assumed.