bluuebunny/crossref_metadata_2025_split huggingface dataset:
Short-duration accretion states of Polars as seen in TESS and ZTF data
Authors: Duffy C , Ramsay G , Wu Kinwah , Mason Paul A , Hakala P , Steeghs D , Wood M A 
Published: September 2022

ABSTRACT
Polars are highly magnetic cataclysmic variables which have been long observed to have both high and low brightness states. The duration of these states has been previously seen to vary from a number of days up to years. Despite this, these states and their physical origin have not been explained in a consistent manner. We present observations of the shortest duration states of a number of Polars observed by ZTF and TESS. This has allowed us to determine that short-duration states are a relatively common feature across the population of Polars. Furthermore, we have been able to generalize the model of star-spot migration to explain both short-lived high and low states in Polars by incorporating the interaction between the magnetic field of the white dwarf and that of the star spots.
The alignment between brightest cluster galaxies and host clusters
Authors: Yuan Z S , Wen Z L 
Published: September 2022

ABSTRACT
The alignment between the brightest cluster galaxies (BCGs) and host clusters can reveal the mystery of the formation and evolution of galaxy clusters. We measure cluster orientations in optical based on the projected distribution of member galaxies and in X-ray by fitting the morphology of intracluster medium (ICM). Cluster orientations determined in the two wavelengths are generally consistent. The orientation alignment between BCGs and host clusters is confirmed and more significant than in previous works. We find that BCGs are more aligned with cluster orientations measured in X-ray than those from optical data. Clusters with a brighter BCG generally show a stronger alignment. We argue that the detected redshift evolution of the alignment is probably caused by observational bias rather than intrinsic evolution. The alignment is not related to the ellipticity of BCGs, and the richness, ellipticity, and dynamical state of host clusters. The strong alignment between BCGs and the morphology of ICMs may be the consequence of the co-evolution between the central massive galaxy and host clusters.
Constraining RV variation using highly reddened Type Ia supernovae from the Pantheon+ sample
Authors: Rose B M , Popovic B , Scolnic D , Brout D 
Published: September 2022

ABSTRACT
Type Ia supernovae (SNe Ia) are powerful tools for measuring the expansion history of the Universe, but the impact of dust around SNe Ia remains unknown and is a critical systematic uncertainty. One way to improve our empirical description of dust is to analyse highly reddened SNe Ia [E(B − V) &gt; 0.4, roughly equivalent to the fitted SALT2 light-curve parameter c &gt; 0.3]. With the recently released Pantheon+ sample, there are 57 SNe Ia that were removed because of their high colour alone (with colours up to c = 1.61), which can provide enormous leverage on understanding line-of-sight RV. Previous studies have claimed that RV decreases with redder colour, though it is unclear if this is due to limited statistics, selection effects, or an alternative explanation. To test this claim, we fit two separate colour–luminosity relationships, one for the main cosmological sample (c &lt; 0.3) and one for highly reddened (c &gt; 0.3) SNe Ia. We find the change in the colour–luminosity coefficient to be consistent with zero. Additionally, we compare the data to simulations with different colour models, and find that the data prefers a model with a flat dependence of RV on colour over a declining dependence. Finally, our results strongly support that line-of-sight RV to SNe Ia is not a single value, but forms a distribution.
A detailed study of the barium central star of the planetary nebula Abell 70
Authors: Jones David , Boffin Henri M J , Brown Alex J , Zak Jiri , Hume George , Munday James , Miszalski Brent 
Published: September 2022

ABSTRACT
We present a detailed study of the barium star at the heart of the planetary nebula Abell 70. Time-series photometry obtained over a period of more than 10 yr demonstrates that the barium-contaminated companion is a rapid rotator with temporal variability due to spots. The amplitude and phasing of the photometric variability change abruptly; however, there is no evidence for a change in the rotation period (P = 2.06 d) over the course of the observations. The co-addition of 17 high-resolution spectra obtained with Ultraviolet and Visual Échelle Spectrograph mounted on the Very Large Telescope allows us to measure the physical and chemical properties of the companion, confirming it to be a chromospherically active, late G-type sub-giant with more than +1 dex of barium enhancement. We find no evidence of radial velocity variability in the spectra, obtained over the course of approximately 130 d with a single additional point some 8 yr later, with the radial velocities of all epochs approximately −10 km s −1 from the previously measured systemic velocity of the nebula. This is perhaps indicative that the binary has a relatively long period (P ≳ 2 yr) and high eccentricity (e ≳ 0.3), and that all the observations were taken around radial velocity minimum. However, unless the binary orbital plane is not aligned with the waist of the nebula or the systemic velocity of the binary is not equal to the literature value for the nebula, this would imply an unfeasibly large mass for the nebular progenitor.
Learning to detect radio frequency interference in radio astronomy without seeing it
Authors: Mesarcik Michael , Boonstra Albert-Jan , Ranguelova Elena , van Nieuwpoort Rob V 
Published: September 2022

ABSTRACT
Radio frequency interference (RFI) corrupts astronomical measurements, thus affecting the performance of radio telescopes. To address this problem, supervised-segmentation models have been proposed as candidate solutions to RFI detection. However, the unavailability of large labelled data sets, due to the prohibitive cost of annotating, makes these solutions unusable. To solve these shortcomings, we focus on the inverse problem: training models on only uncontaminated emissions, thereby learning to discriminate RFI from all known astronomical signals and system noise. We use nearest latent neighbours – an algorithm that utilizes both the reconstructions and latent distances to the nearest neighbours in the latent space of generative autoencoding models for novelty detection. The uncontaminated regions are selected using weak labels in the form of RFI flags (generated by classical RFI flagging methods) available from most radio astronomical data archives at no additional cost. We evaluate performance on two independent data sets, one simulated from the Hydrogen Epoch of Reionization Array (HERA) telescope and the other consisting of real observations from the Low-Frequency Array (LOFAR) telescope. Additionally, we provide a small expert-labelled LOFAR data set (i.e. strong labels) for evaluation of our and other methods. Performance is measured using the area under the receiver operating characteristic (AUROC), area under precision–recall curve (AUPRC), and the maximum F1-score for a fixed threshold. For the simulated HERA data set, we outperform the current state of the art across all metrics. For the LOFAR data set, our algorithm offers both a 4 per cent increase in AUROC and AUPRC at the cost of increasing the false negative rate, but without any manual labelling.
Understanding the relation between thermal Sunyaev–Zeldovich decrement and halo mass using the simba and TNG simulations
Authors: Yang Tianyi , Cai Yan-Chuan , Cui Weiguang , Davé Romeel , Peacock John A , Sorini Daniele 
Published: September 2022

ABSTRACT
The relation between the integrated thermal Sunyaev–Zeldovich (tSZ) y-decrement versus halo mass (Y–M) can potentially constrain galaxy formation models, if theoretical and observational systematics can be properly assessed. We investigate the Y–M relation in the simba and IllustrisTNG-100 cosmological hydrodynamic simulations, quantifying the effects of feedback, line-of-sight projection, and beam convolution. We find that simba’s active galactic nucleus (AGN) jet feedback generates strong deviations from self-similar expectations for the Y–M relation, especially at $M_{\rm 500}\lesssim10^{13}M_\odot$. In simba, this is driven by suppressed in-halo y contributions owing to lowered halo baryon fractions. IllustrisTNG results more closely resemble simba without jets. Projections of line-of-sight structures weaken these model differences slightly, but they remain significant – particularly at group and lower halo masses. In contrast, beam smearing at Planck resolution makes the models indistinguishable, and both models appear to agree well with Planck data down to the lowest masses probed. We show that the arcminute resolution expected from forthcoming facilities would retain the differences between model predictions, and thereby provide strong constraints on AGN feedback.
On modelling cosmic ray sputtering of interstellar grain ices
Authors: Paulive Alec , Carder Joshua T , Herbst Eric 
Published: September 2022

ABSTRACT
In the interstellar medium (ISM), the formation of complex organic molecules (COMs) is largely facilitated by surface reactions. However, in cold dark clouds, thermal desorption of COMs is inefficient because of the lack of thermal energy to overcome binding energies to the grain surface. Non-thermal desorption methods are therefore important explanations for the gas-phase detection of many COMs that are primarily formed on grains. Here, we present a new non-thermal desorption process: cosmic ray sputtering of grain ice surfaces based on water, carbon dioxide, and a simple mixed ice. Our model applies estimated rates of sputtering to the three-phase rate equation model nautilus-1.1, where this inclusion results in enhanced gas-phase abundances for molecules produced by grain reactions such as methanol (CH3OH) and methyl formate (HCOOCH3). Notably, species with efficient gas-phase destruction pathways exhibit less of an increase in models with sputtering compared to other molecules. These model results suggest that sputtering is an efficient, non-specific method of non-thermal desorption that should be considered as an important factor in future chemical models.
Map-based cosmology inference with lognormal cosmic shear maps
Authors: Boruah Supranta S , Rozo Eduardo , Fiedorowicz Pier 
Published: September 2022

ABSTRACT
Most cosmic shear analyses to date have relied on summary statistics (e.g. ξ+ and ξ−). These types of analyses are necessarily suboptimal, as the use of summary statistics is lossy. In this paper, we forward-model the convergence field of the Universe as a lognormal random field conditioned on the observed shear data. This new map-based inference framework enables us to recover the joint posterior of the cosmological parameters and the convergence field of the Universe. Our analysis properly accounts for the covariance in the mass maps across tomographic bins, which significantly improves the fidelity of the maps relative to single-bin reconstructions. We verify that applying our inference pipeline to Gaussian random fields recovers posteriors that are in excellent agreement with their analytical counterparts. At the resolution of our maps – and to the extent that the convergence field can be described by the lognormal model – our map posteriors allow us to reconstruct all summary statistics (including non-Gaussian statistics). We forecast that a map-based inference analysis of LSST-Y10 data can improve cosmological constraints in the σ8–Ωm plane by $\approx\!{30}{{\ \rm per\ cent}}$ relative to the currently standard cosmic shear analysis. This improvement happens almost entirely along the $S_8=\sigma _8\Omega _{\rm m}^{1/2}$ directions, meaning map-based inference fails to significantly improve constraints on S8.
GROWTH on S190426c II: GROWTH-India Telescope search for an optical counterpart with a custom image reduction and candidate vetting pipeline
Authors: Kumar Harsh , Bhalerao Varun , Anupama G C , Barway Sudhanshu , Coughlin Michael W , De Kishalay , Deshmukh Kunal , Dutta Anirban , Goldstein Daniel A , Jassani Adeem , Joharle Simran , Karambelker Viraj , Khandagale Maitreya , Kumar Brajesh , Saraogi Divita , Sharma Yashvi , Shenoy Vedant , singer Leo , Singh Avinash , Waratkar Gaurav 
Published: September 2022

ABSTRACT
S190426c/GW190426_152155 was the first probable neutron star–black hole merger candidate detected by the LIGO-Virgo Collaboration. We undertook a tiled search for optical counterparts of this event using the 0.7-m GROWTH-India Telescope. Over a period of two weeks, we obtained multiple observations over a 22.1 deg2 area, with a 17.5 per cent probability of containing the source location. Initial efforts included obtaining photometry of sources reported by various groups, and a visual search for sources in all galaxies contained in the region. Subsequently, we have developed an image subtraction and candidate vetting pipeline with $\sim 94{{\ \rm per\ cent}}$ efficiency for transient detection. Processing the data with this pipeline, we find several transients, but none that are compatible with kilonova models. We present the details of our observations, the working of our pipeline, results from the search, and our interpretations of the non-detections that will work as a pathfinder during the O4 run of LVK.
A measurement of Hubble’s Constant using Fast Radio Bursts
Authors: James C W , Ghosh E M , Prochaska J X , Bannister K W , Bhandari S , Day C K , Deller A T , Glowacki M , Gordon A C , Heintz K E , Marnoch L , Ryder S D , Scott D R , Shannon R M , Tejos N 
Published: September 2022

ABSTRACT
We constrain the Hubble constant H0 using Fast Radio Burst (FRB) observations from the Australian Square Kilometre Array Pathfinder (ASKAP) and Murriyang (Parkes) radio telescopes. We use the redshift-dispersion measure (‘Macquart’) relationship, accounting for the intrinsic luminosity function, cosmological gas distribution, population evolution, host galaxy contributions to the dispersion measure (DMhost), and observational biases due to burst duration and telescope beamshape. Using an updated sample of 16 ASKAP FRBs detected by the Commensal Real-time ASKAP Fast Transients (CRAFT) Survey and localized to their host galaxies, and 60 unlocalized FRBs from Parkes and ASKAP, our best-fitting value of H0 is calculated to be $73_{-8}^{+12}$ km s−1 Mpc−1. Uncertainties in FRB energetics and DMhost produce larger uncertainties in the inferred value of H0 compared to previous FRB-based estimates. Using a prior on H0 covering the 67–74 km s−1 Mpc−1 range, we estimate a median ${\rm DM}_{\rm host}= 186_{-48}^{+59}\,{\rm pc \, cm^{-3}}$, exceeding previous estimates. We confirm that the FRB population evolves with redshift similarly to the star-formation rate. We use a Schechter luminosity function to constrain the maximum FRB energy to be log10Emax$=41.26_{-0.22}^{+0.27}$ erg assuming a characteristic FRB emission bandwidth of 1 GHz at 1.3 GHz, and the cumulative luminosity index to be $\gamma =-0.95_{-0.15}^{+0.18}$. We demonstrate with a sample of 100 mock FRBs that H0 can be measured with an uncertainty of ±2.5 km s−1 Mpc−1, demonstrating the potential for clarifying the Hubble tension with an upgraded ASKAP FRB search system. Last, we explore a range of sample and selection biases that affect FRB analyses.
Asymptotic model for a bi-component system with a very large mass ratio mh/ml of their constituting particles
Authors: Gomez-Leyton Yuvineza J , Velazquez Luisberis 
Published: September 2022

ABSTRACT
We address the asymptotic limit of the γ-exponential model for a bi-component system with a very large ratio mh/ml between the masses of their constituting particles. The simplest model that captures this limit situation is an isothermal gas of non-relativistic point particles under an external harmonic potential $V\left(\mathbf {r}\right)=m\, \omega ^{2}_{0}\, \mathbf {r}^{2}/2$ that mimics the gravitational influence of the lightest particles in the central regions. We revisit the study of this self-gravitating model by including the anisotropy due to the system rotation. The thermodynamics of this situation is hallmarked by the gravitational radius$r_{c}=\left(G\, M/\omega ^{2}_{0}\right)^{1/3}$ and finite values of the rotation frequency ω &lt; ω0, where M is the system total mass. The axially symmetric solutions of this model predicts spheroidal profiles with any value of the angular momentum, whose anisotropy is driven via the dimensionless parameter $\varepsilon =\omega ^{2}/\omega ^{2}_{0}$. In general, the thermodynamics is significantly affected by the system rotation. Considering the limit ε → 1, in particular, our calculations predict that the temperature at gravothermal collapse goes to zero and the main components of the inertia tensor diverge. Finally, we apply the present model to perform an analysis of star distributions under the gravitational influence of dark matter haloes in some dwarf spheroidal galaxies. Our interest is focused on the applicability conditions of the present model to these stellar systems.
Algebraic and machine learning approach to hierarchical triple-star stability
Authors: Vynatheya Pavan , Hamers Adrian S , Mardling Rosemary A , Bellinger Earl P 
Published: September 2022

ABSTRACT
We present two approaches to determine the dynamical stability of a hierarchical triple-star system. The first is an improvement on the Mardling–Aarseth stability formula from 2001, where we introduce a dependence on inner orbital eccentricity and improve the dependence on mutual orbital inclination. The second involves a machine learning approach, where we use a multilayer perceptron (MLP) to classify triple-star systems as ‘stable’ and ‘unstable’. To achieve this, we generate a large training data set of 106 hierarchical triples using the N-body code MSTAR. Both our approaches perform better than previous stability criteria, with the MLP model performing the best. The improved stability formula and the machine learning model have overall classification accuracies of $93{{\ \rm per\ cent}}$ and $95{{\ \rm per\ cent}}$ respectively. Our MLP model, which accurately predicts the stability of any hierarchical triple-star system within the parameter ranges studied with almost no computation required, is publicly available on Github in the form of an easy-to-use python script.
Characterising murine hippocampal iron homeostasis, in relation to markers of brain inflammation and metabolism, during ageing
Authors: Ellison Gaewyn , Duong Lelinh , Hollings Ashley , Howard Daryl , Jackaman Connie , Hackett Mark J 
Published: September 2022

Abstract
Metal ions (Fe, Cu, and Zn) are essential to a healthy brain function, with the amount, localisation, and chemical form often tightly controlled. Evidence points towards loss of metal ion homeostasis within the ageing brain; in particular brain Fe accumulation appears to be a hallmark of ageing, which may place the brain at a greater risk of neurodegenerative disease. Unfortunately, the cause or consequence of altered brain metal ion homeostasis during ageing remains unknown, and there is a lack of data comparing brain metal ion homeostasis with other events of the ageing process (e.g. brain metabolism, brain inflammation). This study has utilised a multi-modal approach that incorporated: X-ray fluorescence microscopy for elemental mapping of metal ion homeostasis, Perl's Fe histochemistry, FTIR spectroscopic biochemical imaging of lactate and protein aggregates, and immuno-fluorescence analysis of markers of brain inflammation and Fe storage proteins (heavy-chain ferritin, light-chain ferritin, and mitochondrial ferritin). Interestingly, while age-related Fe accumulation was observed in corpus callosum white matter of murine (C56BL/6J) brain tissue (concomitant with elevated levels of markers of brain inflammation and altered metabolism), Fe content was not altered within the hippocampus (a decrease in total Zn within the mossy fibres was observed). Ultimately, the results of this study demonstrate an important association between elevated brain Fe and brain inflammation during natural ageing. This study also highlights that future research is required to image different chemical forms of Fe with respect to changes in brain metabolism and inflammation, as well as localising these changes to specific cell types.
The absence of the queuosine tRNA modification leads to pleiotropic phenotypes revealing perturbations of metal and oxidative stress homeostasis in Escherichia coli K12
Authors: Pollo-Oliveira Leticia , Davis Nick K , Hossain Intekhab , Ho Peiying , Yuan Yifeng , Salguero García Pedro , Pereira Cécile , Byrne Shane R , Leng Jiapeng , Sze Melody , Blaby-Haas Crysten E , Sekowska Agnieszka , Montoya Alvaro , Begley Thomas , Danchin Antoine , Aalberts Daniel P , Angerhofer Alexander , Hunt John , Conesa Ana , Dedon Peter C , de Crécy-Lagard Valérie 
Published: September 2022

Abstract
Queuosine (Q) is a conserved hypermodification of the wobble base of tRNA containing GUN anticodons but the physiological consequences of Q deficiency are poorly understood in bacteria. This work combines transcriptomic, proteomic and physiological studies to characterize a Q-deficient Escherichia coli K12 MG1655 mutant. The absence of Q led to an increased resistance to nickel and cobalt, and to an increased sensitivity to cadmium, compared to the wild-type (WT) strain. Transcriptomic analysis of the WT and Q-deficient strains, grown in the presence and absence of nickel, revealed that the nickel transporter genes (nikABCDE) are downregulated in the Q– mutant, even when nickel is not added. This mutant is therefore primed to resist to high nickel levels. Downstream analysis of the transcriptomic data suggested that the absence of Q triggers an atypical oxidative stress response, confirmed by the detection of slightly elevated reactive oxygen species (ROS) levels in the mutant, increased sensitivity to hydrogen peroxide and paraquat, and a subtle growth phenotype in a strain prone to accumulation of ROS.
Gallium(III)-pyridoxal thiosemicarbazone derivatives as nontoxic agents against Gram-negative bacteria
Authors: Scaccaglia Mirco , Rega Martina , Vescovi Marianna , Pinelli Silvana , Tegoni Matteo , Bacci Cristina , Pelosi Giorgio , Bisceglie Franco 
Published: September 2022

Abstract
Many bacterial strains are developing mechanism of resistance to antibiotics, rendering last-resort antibiotics inactive. Therefore, new drugs are needed and in particular metal-based compounds represent a valid starting point to explore new antibiotic classes. In this study, we have chosen to investigate gallium(III) complexes for their potential antimicrobial activity against different strains of Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa which have developed different type of resistance mechanism, including the expression of β-lactamases (NDM-1, ESβL, or AmpC) or the production of biofilm. We studied a series of thiosemicarbabazones derived from pyridoxal, their related Ga(III) complexes, and the speciation in solution of the Ga(III)/ligand systems as a function of the pH. Proton dissociation constants and conditional stability constants of Ga(III) complexes were evaluated by UV/Vis spectroscopy, and the most relevant species at physiological pH were identified. The compounds are active against resistant Gram-negative strain with minimal inhibitory concentration in the μM range, while no cytotoxicity was detected in eukaryotic cells.