bluuebunny/crossref_metadata_2025_split huggingface dataset:
The wind of rotating B supergiants – II. The δ-slow hydrodynamic regime
Authors: Venero R O J , Curé M , Puls J , Cidale L S , Haucke M , Araya I , Gormaz-Matamala A , Arcos C 
Published: November 2023

ABSTRACT
The theory of line-driven winds can explain many observed spectral features in early-type stars, though our understanding the winds of B supergiants remains incomplete. The hydrodynamic equations for slowly rotating stellar winds predict two regimes based on the line-force parameter δ: the fast and the δ-slow solution. In this paper, we aim to explore the capability of the latter to explain the observed properties of B supergiant winds. We calculate Hα line profiles, the most sensitive wind diagnostics in the optical, for both fast and δ-slow wind models. We fit them to observed data from a well-studied sample of B supergiants, by adapting the line-force parameters (k, α, and δ) of the hydrodynamic model. Unexpectedly, the observed Hα spectra can be reproduced by both hydrodynamic wind regimes with similar precision. We argue that this similarity results from the similar shape of the normalized velocity law produced by both regimes in the lower, Hα-forming wind region. Our findings raise a dichotomy, because mass-loss rates and terminal velocities (v∞) for each solution are quite different. The δ-slow solution predicts maximum values for v∞ that are systematically lower than those measured in the ultraviolet, whereas the v∞ values of the fast solution are closer, and probably more appropriate. However, our results also indicate that the δ-slow solution might better describe the dense winds of B hypergiants. Multiwavelength analyses and a larger sample of stars are needed to reach a definitive conclusion.
Multiwavelength analysis of Fermi-LAT blazars with high-significance periodicity: detection of a long-term rising emission in PG 1553+113
Authors: Peñil P , Westernacher-Schneider J R , Ajello M , Domínguez A , Buson S , Otero-Santos J , Marcotulli L , Torres−Albà N , Zrake J 
Published: November 2023

ABSTRACT
Blazars display variable emission across the entire electromagnetic spectrum, with time-scales that can range from a few minutes to several years. Our recent work has shown that a sample of five blazars exhibit hints of periodicity with a global significance ${\gtrsim}2\, \sigma$ at γ-ray energies, in the range of 0.1 GeV &lt; E &lt; 800 GeV. In this work, we study their multiwavelength emission, covering the X-ray, ultraviolet, optical, and radio bands. We show that three of these blazars present similar periodic patterns in the optical and radio bands. Additionally, fluxes in the different bands of the five blazars are correlated, suggesting a co-spatial origin. Moreover, we detect a long-term (≈10 yr) rising trend in the light curves of PG 1553+113, and we use it to infer possible constraints on the binary black hole hypothesis.
Microphysical parameter variation in gamma-ray burst stratified afterglows and closure relations: from sub-GeV to TeV observations
Authors: Fraija Nissim , Dainotti Maria G , Betancourt Kamenetskaia Boris , Galván-Gámez Antonio , Aguilar-Ruiz Edilberto 
Published: November 2023

ABSTRACT
Gamma-ray bursts (GRBs) are one of the most exciting sources that offer valuable opportunities for investigating the evolution of energy fraction given to magnetic fields and particles through microphysical parameters during relativistic shocks. The delayed onset of GeV–TeV radiation from bursts detected by the Fermi Large Area Telescope and Cherenkov Telescopes provide crucial information in favour of the external-shock model. Derivation of the closure relations (CRs) and the light curves in external shocks requires knowledge of GRB afterglow physics. In this manuscript, we derive the CRs and light curves in a stratified medium with variations of microphysical parameters of the synchrotron and synchrotron self-Compton (SSC) afterglow model radiated by an electron distribution with a hard and soft spectral index. Using Markov chain Monte Carlo simulations, we apply the current model to investigate the evolution of the spectral and temporal indices of those GRBs reported in the Second Gamma-ray Burst Catalog (2FLGC), which comprises 29 bursts with photon energies above 10 GeV and of those bursts (GRB 180720B, 190114C, 190829A, and 221009A) with energetic photons above 100 GeV, which can hardly be modelled with the CRs of the standard synchrotron scenario. The analysis shows that (i) the most likely afterglow model using synchrotron and SSC emission on the 2FLGC corresponds to the constant-density scenario, and (ii) variations of spectral (temporal) index keeping the temporal (spectral) index constant could be associated with the evolution of microphysical parameters, as exhibited in GRB 190829A and GRB 221009A.
Investigating the multidrifting behaviour of subpulses in PSR J2007 + 0910 with the FAST
Authors: Xu Xin , Shang Lunhua , Zhi Qijun , Dang Shijun , Dai Shi , Tian Jie , Yu Yan , Li Qingying , Xiao Shuo , Zhang Dandan 
Published: November 2023

ABSTRACT
The multidrifting subpulse behaviours in PSR J2007 + 0910 have been studied carefully with the high sensitivity observations of the Five-hundred-meter Aperture Spherical radio Telescope (FAST) at 1250 MHz. We found that there are at least six different single emission modes in PSR J2007 + 0910 are observed, four of which show significant subpulse drifting behaviours (modes A, B, C, and D), and the remaining two (modes E1 and E2) show stationary subpulse structures. The subpulse drifting periods of modes A, B, C, and D are P3,A = 8.7 ± 1.6P, P3,B = 15.8 ± 1.2P, P3,C = 21.6 ± 1.3P, and P3,D = 32.3 ± 0.9P, respectively, where P represents the pulse period of this pulsar. The subpulse separation is almost the same for all modes P2 = 6.01 ± 0.18°. Deep analysis suggests that the appearance and significant changes in the drifting period of multidrifting subpulse emission modes for a pulsar may originate from the aliasing effect. The observed non-drifting modes may be caused by the spark point move with a period ∼P2. Our statistical analysis shows that the drift mode of this pulsar almost always switches from slower to faster drifts in the mode change. The interesting subpulse emission phenomenon of PSR J2007 + 0910 provides a unique opportunity to understand the switching mechanism of multidrift mode.
Unsupervised machine learning classification of Fermi gamma-ray bursts using spectral parameters
Authors: Chen Jia-Ming , Zhu Ke-Rui , Peng Zhao-Yang , Zhang Li 
Published: November 2023

ABSTRACT
A thorough analysis of 2297 gamma-ray bursts (GRBs) in the Fermi catalogue is performed by using unsupervised machine learning algorithms in this paper. In our analysis, for two spectral parameter samples, namely for the peak-flux and time-integrated spectral fits, two dimensionality reduction algorithms, t-distributed stochastic neighbour embedding (t-SNE), and uniform manifold approximation and projection (UMAP), are used to generate four embedding maps; further, K-means algorithm is used for searching for the optimal clustering on the four maps. Our results show that Fermi GRBs can be well separated into two groups. For the time-integrated spectral parameters, both UMAP and t-SNE algorithms classify 372 bursts as short GRBs and 1925 bursts as long GRBs, and 384 bursts as short GRBs and 1913 bursts as long GRBs for the peak-time spectral parameters. This new classification method differs from traditional long and short classifications because it is not based on duration. In addition, it is found that the classification results of 11 GRBs are inconsistent between the integrated and peak-time spectral samples. GRB200826A is the first confirmed short GRB of collapsar origin, and the physical origins of these GRBs may be similar to it.
Not gone with the wind: survival of high-velocity molecular clouds in the galactic centre
Authors: Zhang Mengfei , Li Miao 
Published: November 2023

ABSTRACTHigh-velocity atomic clouds in the Galactic centre have attracted significant attention due to their enigmatic formation process, which is potentially linked to the starburst or supermassive black hole activities in the region. Further, the discovery of high-velocity molecular clouds (HVMCs) presents a greater puzzle, because they are much denser and more massive. If the HVMCs were accelerated by the strong activities in the Galactic centre, they are expected to be destroyed before they reach such a high velocity. To shed light on this phenomenon, we perform 3D numerical simulations to investigate the origin and hydrodynamic evolution of HVMCs during a starburst in the Galactic centre. We find that the presence of a magnetic field provides effective protection and acceleration to molecular clouds (MCs) within the galactic winds. Consequently, the MCs can attain latitudes of approximately 1 kpc with velocities around 200 km s−1, consistent with the observed characteristics of HVMCs. The consistency of our findings across a wide parameter space supports the conclusion that HVMCs can indeed withstand the starburst environment in the Galactic centre, providing valuable insights into their survival mechanisms.
Impact of tidal environment on galaxy clustering in GAMA
Authors: Alam Shadab , Paranjape Aseem , Peacock John A 
Published: November 2023

ABSTRACT
We constrain models of the galaxy distribution in the cosmic web using data from the Galaxy and Mass Assembly (GAMA) survey. We model the redshift-space behaviour of the 2-point correlation function (2pcf) and the recently proposed Voronoi volume function (VVF) – which includes information beyond two-point statistics. We extend the standard halo model using extra satellite degrees of freedom and two assembly bias parameters: αcen and αsat, which correlate the occupation numbers of central and satellite galaxies with their host halo’s tidal environment, respectively. We measure $\alpha _{\rm sat}=1.44^{+0.25}_{-0.43}$ and $\alpha _{\rm cen}=-0.79^{+0.29}_{-0.11}$ using a combination of 2pcf and VVF measurements, representing a detection of assembly bias at the 3.3σ (2.4σ) significance level for satellite (central) galaxies. This result remains robust to possible anisotropies in the halocentric distribution of satellites as well as technicalities of estimating the data covariance. We show that the growth rate (fσ8) deduced using models with assembly bias is about 7 per cent (i.e. 1.5σ) lower than if assembly bias is ignored. When projected on to the Ωm–σ8 plane, the model constraints without assembly bias overlap with Planck expectations, while allowing assembly bias introduces significant tension with Planck, preferring either a lower Ωm or a lower σ8. Finally, we find that the all-galaxy weak-lensing signal is unaffected by assembly bias, but the central and satellite sub-populations individually show significantly different signals in the presence of assembly bias. Our results illustrate the importance of accurately modelling galaxy formation for cosmological inference from future surveys.
The H i-rich ultra-diffuse galaxies follow the extended Schmidt law
Authors: Zhai Sai , Shi Yong , Zhang Zhi-Yu , Wang Jun-Zhi , Gao Yu , Gu Qiusheng , Wang Tao , Du Kaiyi , Yu Xiaoling , Li Xin 
Published: November 2023

ABSTRACT
The ${\rm H\, {\small I}}$-rich ultra-diffuse galaxies (HUDGs) offer a unique case for studies of star formation laws as they host low star formation efficiency and low-metallicity environments where gas is predominantly atomic. We collect a sample of six HUDGs in the field and investigate their location in the extended Schmidt law ($\Sigma _{\text{SFR }} \propto \left(\Sigma _{\text{star}}^{0.5} \Sigma _{\text{gas}}\right)^{1.09}$). They are consistent with this relationship well (with deviations of only 1.1σ). Furthermore, we find that HUDGs follow the tight correlation between the hydrostatic pressure in the galaxy mid-plane and the quantity on the x-axis ($\rm log(\Sigma _{star}^{0.5}\Sigma _{gas})$) of the extended Schmidt law. This result indicates that these HUDGs can be self-regulated systems that reach the dynamical and thermal equilibrium. In this framework, the stellar gravity compresses the disc vertically and counteracts the gas pressure in the galaxy mid-plane to regulate the star formation as suggested by some theoretical models.
The physical origins of gas in the circumgalactic medium using observationally motivated TNG50 mocks
Authors: Weng Simon , Péroux Céline , Ramesh Rahul , Nelson Dylan , Sadler Elaine M , Zwaan Martin , Bollo Victoria , Casavecchia Benedetta 
Published: November 2023

ABSTRACT
Absorbers in the spectrum of background objects probe the circumgalactic medium (CGM) surrounding galaxies, but its physical properties remain unconstrained. We use the cosmological hydrodynamical simulation TNG50 to statistically trace the origins of ${\rm H\, {\small I}}$ Ly α absorbers around galaxies at z = 0.5 with stellar masses ranging from 108 to 1011 M⊙. We emulate observational CGM studies by considering all gas within a line of sight velocity range of ±500 kms−1 from the central, to quantitatively assess the impact of other galaxy haloes and overdense gas in the IGM that intersect sightlines. We find that 75 per cent of ${\rm H\, {\small I}}$ absorbers with column densities $\log [N(\mbox{${\rm H\, {\small I}}$})/\rm {cm}^{-2}]\gt 16.0$ trace the central galaxy within ±150 (80) kms−1 of M* = 1010(108) M⊙ central galaxies. The impact of satellites to the total absorber fraction is most significant at impact parameters 0.5Rvir &lt; b &lt; Rvir, and satellites with masses below typical detection limits (M* &lt; 108 M⊙) account for 10 (40) per cent of absorbers that intersect any satellite bound to 1010 and 1011 (109) M⊙ centrals. After confirming outflows are more dominant along the minor axis, we additionally show that at least 20 per cent of absorbers exhibit no significant radial movement, indicating that absorbers can also trace quasi-static gas. Our work shows that determining the stellar mass of galaxies at zabs is essential to constrain the physical origin of the gas traced in absorption, which in turn is key to characterizing the kinematics and distribution of gas and metals in the CGM.
The giant nature of WD 1856 b implies that transiting rocky planets are rare around white dwarfs
Authors: Kipping David 
Published: November 2023

ABSTRACT
White dwarfs (WDs) have roughly Earth-sized radii – a fact long recognized to facilitate the potential discovery of sub-Earth-sized planets via transits, as well as atmospheric characterization including biosignatures. Despite this, the first (and still only) transiting planet discovered in 2020 was a roughly Jupiter-sized world, found using Transiting Exoplanet Survey Satellite (TESS) photometry. Given the relative paucity of giant planets compared to terrestrials indicated by both exoplanet demographics and theoretical simulations (a ‘bottom-heavy’ radius distribution), this is perhaps somewhat surprising. Here, we quantify the surprisingness of this fact accounting for geometric bias and detection bias assuming (1) a bottom-heavy Kepler-derived radius distribution and (2) a top-heavy radial velocity-inspired radius distribution. Both are concerning, with the latter implying that rocky planets are highly unusual and the former implying that WD 1856 b would have to be highly surprising event at the &lt;0.5 per cent level. Using a hierarchical Bayesian model, we infer the implied power-law radius distribution conditioned upon WD 1856 b and arrive at a top-heavy distribution, such that 0.1–2 R⊕ planets are an order-of-magnitude less common than 2–20 R⊕ planets in the period range of 0.1–10 d. The implied hypothesis is that transiting WD rocky planets are rare. We discuss ways to reconcile this with other evidence for minor bodies around WDs, and ultimately argue that it should be easily testable.
Detection of X-ray/UV delay in NGC 4051 using AstroSat observations
Authors: Kumari Kavita , Dewangan G C , Papadakis I E , Singh K P 
Published: November 2023

ABSTRACT
We study the connection between the variations in the far-ultraviolet (FUV), near-ultraviolet (NUV), and X-ray band emission from NGC 4051 using 4 d long AstroSat observations performed during 5–9 June 2016. NGC 4051 showed rapid variability in all three bands with the strongest variability amplitude in the X-ray band ($F_{\mathrm{ var}} \sim 37~{{\ \rm per\ cent}}$) and much weaker variability in the UV bands ($F_{\mathrm{ var}} \sim 3{\!-\!}5~{{\ \rm per\ cent}}$). Cross-correlation analysis performed using interpolated cross-correlation functions and discrete cross-correlation functions revealed a robust correlation (∼0.75) between the UV and X-ray light curves. The variations in the X-ray band are found to lead those in the FUV and NUV bands by ∼7.4 ks and ∼24.2 ks, respectively. The UV lags favour the thermal disc reprocessing model. The FUV and NUV bands are strongly correlated (∼0.9) and the variations in the FUV band lead those in the NUV band by ∼13 ks. Comparison of the UV lags found using the AstroSat observations with those reported earlier and the theoretical model for thermal reverberation timelag suggests a possible change in either the geometry of the accretion disc/corona or the height of the corona.
Infrared spectroscopy of SWIFT J0850.8−4219: identification of the second red supergiant X-ray binary in the Milky Way
Authors: De Kishalay , Daly Fiona A , Soria Roberto 
Published: November 2023

ABSTRACT
High-mass X-ray binaries hosting red supergiant (RSG) donors are a rare but crucial phase in massive stellar evolution, with only one source previously known in the Milky Way. In this letter, we present the identification of the second Galactic RSG X-ray binary SWIFT J0850.8−4219. We identify the source 2MASS 08504008−4211514 as the likely infrared counterpart with a chance coincidence probability ≈5 × 10−6. We present a $1.0{\!-\!}2.5\, \mu$m spectrum of the counterpart, exhibiting features characteristic of late-type stars and an exceptionally strong He i emission line, corroborating the identification. Based on i) the strength of the 12CO(2,0) band, ii) strong CN bandheads and absent TiO bandheads at ≈1.1 µm and iii) equivalent width of the Mg i$1.71\, \mu$m line, we classify the counterpart to be a K3–K5 type RSG with an effective temperature of 3820 ± 100 K, located at a distance of ≈12 kpc. We estimate the source X-ray luminosity to be (4 ± 1) × 1035 erg s−1, with a hard photon index (Γ &lt; 1), arguing against a white dwarf accretor but consistent with a magnetized neutron star in the propeller phase. Our results highlight the potential of systematic near-infrared spectroscopy of Galactic hard X-ray sources in completing our census of the local X-ray binary population.
Metagenomics harvested genus-specific single-stranded DNA-annealing proteins improve and expand recombineering in Pseudomonas species
Authors: Asin-Garcia Enrique , Garcia-Morales Luis , Bartholet Tessa , Liang Zhuobin , Isaacs Farren J , Martins dos Santos Vitor A P 
Published: November 2023

Abstract
The widespread Pseudomonas genus comprises a collection of related species with remarkable abilities to degrade plastics and polluted wastes and to produce a broad set of valuable compounds, ranging from bulk chemicals to pharmaceuticals. Pseudomonas possess characteristics of tolerance and stress resistance making them valuable hosts for industrial and environmental biotechnology. However, efficient and high-throughput genetic engineering tools have limited metabolic engineering efforts and applications. To improve their genome editing capabilities, we first employed a computational biology workflow to generate a genus-specific library of potential single-stranded DNA-annealing proteins (SSAPs). Assessment of the library was performed in different Pseudomonas using a high-throughput pooled recombinase screen followed by Oxford Nanopore NGS analysis. Among different active variants with variable levels of allelic replacement frequency (ARF), efficient SSAPs were found and characterized for mediating recombineering in the four tested species. New variants yielded higher ARFs than existing ones in Pseudomonas putida and Pseudomonas aeruginosa, and expanded the field of recombineering in Pseudomonas taiwanensisand Pseudomonas fluorescens. These findings will enhance the mutagenesis capabilities of these members of the Pseudomonas genus, increasing the possibilities for biotransformation and enhancing their potential for synthetic biology applications.
COLOCdb: a comprehensive resource for multi-model colocalization of complex traits
Authors: Pan Siyu , Kang Hongen , Liu Xinxuan , Li Shuhua , Yang Peng , Wu Mingqiu , Yuan Na , Lin Shiqi , Zheng Qiwen , Jia Peilin 
Published: November 2023

Abstract
Large-scale genome-wide association studies (GWAS) have provided profound insights into complex traits and diseases. Yet, deciphering the fine-scale molecular mechanisms of how genetic variants manifest to cause the phenotypes remains a daunting task. Here, we present COLOCdb (https://ngdc.cncb.ac.cn/colocdb), a comprehensive genetic colocalization database by integrating more than 3000 GWAS summary statistics and 13 types of xQTL to date. By employing two representative approaches for the colocalization analysis, COLOCdb deposits results from three key components: (i) GWAS-xQTL, pair-wise colocalization between GWAS loci and different types of xQTL, (ii) GWAS–GWAS, pair-wise colocalization between the trait-associated genetic loci from GWASs and (iii) xQTL–xQTL, pair-wise colocalization between the genetic loci associated with molecular phenotypes in xQTLs. These results together represent the most comprehensive colocalization analysis, which also greatly expands the list of shared variants with genetic pleiotropy. We expect that COLOCdb can serve as a unique and useful resource in advancing the discovery of new biological mechanisms and benefit future functional studies.
Rapid in situ RNA imaging based on Cas12a thrusting strand displacement reaction
Authors: Cheng Xiaoxue , Li Xiaosong , Kang Yuexi , Zhang Decai , Yu Qiubo , Chen Junman , Li Xinyu , Du Li , Yang Tiantian , Gong Yao , Yi Ming , Zhang Songzhi , Zhu Shasha , Ding Shijia , Cheng Wei 
Published: November 2023

Abstract
RNA In situ imaging through DNA self-assembly is advantaged in illustrating its structures and functions with high-resolution, while the limited reaction efficiency and time-consuming operation hinder its clinical application. Here, we first proposed a new strand displacement reaction (SDR) model (Cas12a thrusting SDR, CtSDR), in which Cas12a could overcome the inherent reaction limitation and dramatically enhance efficiency through energy replenishment and by-product consumption. The target-initiated CtSDR amplification was established for RNA analysis, with order of magnitude lower limit of detection (LOD) than the Cas13a system. The CtSDR-based RNA in situ imaging strategy was developed to monitor intra-cellular microRNA expression change and delineate the landscape of oncogenic RNA in 66 clinic tissue samples, possessing a clear advantage over classic in situ hybridization (ISH) in terms of operation time (1 h versus 14 h) while showing comparable sensitivity and specificity. This work presents a promising approach to developing advanced molecular diagnostic tools.