bluuebunny/crossref_metadata_2025_split huggingface dataset:
The evolution of HCO+ in molecular clouds using a novel chemical post-processing algorithm
Authors: Panessa M , Seifried D , Walch S , Gaches B , Barnes A T , Bigiel F , Neumann L 
Published: June 2023

ABSTRACT
Modelling the chemistry of molecular clouds is critical to accurately simulating their evolution. To reduce computational cost, 3D simulations generally restrict their chemistry to species with strong heating and cooling effects. Time-dependent information about the evolution of other species is therefore often neglected. We address this gap by post-processing tracer particles in the SILCC-Zoom molecular cloud simulations. Using a chemical network of 39 species and 301 reactions (including freeze-out of CO and H2O) and a novel algorithm to reconstruct a density grid from sparse tracer particle data, we produce time-dependent density distributions for various species. We focus upon the evolution of HCO+, which is a critical formation reactant of CO but is not typically modelled on the fly. We find that ∼ 90 per cent of the HCO+ content of the cold molecular gas forms in situ around nHCO+ ∼ 103–104 cm−3, over a time-scale of approximately 1 Myr. The remaining ∼ 10 per cent forms at high extinction sites, with minimal turbulent mixing out into the less dense gas. We further show that the dominant HCO+ formation pathway is dependent on the visual extinction, with the reaction H3+ + CO contributing 90 per cent of the total HCO+ production above AV, 3D = 3. We produce the very first maps of the HCO+ column density, N(HCO+), and show that it reaches values as high as 1015 cm−2. We find that 50 per cent of the HCO+ mass is located within AV ∼ 10–30 in a density range of 103.5–104.5 cm−3. Our maps of N(HCO+) are shown to be in good agreement with recent observations of the W49A star-forming region.
The OH Megamaser emission in Arp 220: the rest of the story
Authors: Baan Willem A , Aditya J N H S , An Tao , Klöckner Hans-Rainer 
Published: June 2023

ABSTRACT
The OH Megamaser emission in the merging galaxy Arp 220 has been re-observed with the Multi-Element Radio Linked Interferometer Network (MERLIN) and the European VLBI Network (EVN). Imaging results of the OH line emission at the two nuclei are found to be consistent with earlier observations and confirm additional extended emission structures surrounding the nuclei. Detailed information about the distributed emission components around the two nuclei has been obtained using a concatenated MERLIN and EVN database with intermediate (40 mas) spatial resolution. Continuum imaging shows a relatively compact West nucleus and a more extended East nucleus in addition to an extended continuum ridge stretching below and beyond the two nuclei. Spectral line imaging show extended emission regions at both nuclei together with compact components and additional weaker components north and south of the West nucleus. Spectral line analysis indicates that the dominant OH line emission originates in foreground molecular material that is part of a large-scale molecular structure that engulfs the whole nuclear region. Compact OH components are representative of star formation regions within the two nearly edge-on nuclei and define the systemic velocities of East and West as 5425 and 5360 km s−1. The foreground material at East and West has a 100 km s−1 lower velocity at 5314 and 5254 km s−1. These emission results confirm a maser amplification scenario where the background continuum and the line emission of the star formation regions are amplified by foreground masering material that is excited by the far-infrared radiation field originating in the two nuclear regions.
SALT spectroscopy of the HMXB associated with the LMC supernova remnant MCSNR J0513−6724
Authors: Gvaramadze V V , Kniazev A Y , Castro N , Katkov I Y 
Published: June 2023

ABSTRACT
We report the results of optical échelle spectroscopy with the Southern African Large Telescope (SALT) of the mass donor star BSDL923 in the neutron star (NS) high-mass X-ray binary XMMU J051342.6−672412 associated with the LMC supernova remnant (SNR) MCSNR J0513−6724. We found that BSDL923 is a B0.7 III star with double peaked emission lines originating in a circumbinary disc-like structure. Modelling with the stellar atmosphere code fastwind was used to derive Teff = 27 000 K, log g = 3.22, $v\sin i\approx 100\, {\rm \, km\, s^{-1}}$ and $\log (L_*/\rm \, L_\odot)=5.46$ of BSDL923, as well as to show that the surface of this star is polluted with α-elements from the supernova ejecta. We found also that the NS is orbiting BSDL923 in an eccentric orbit with the orbital period of 1.280 d and the semimajor axis of $17\pm 3 \,R_\odot$, which is less than or equal to the radius of BSDL923 of $25\pm 5 \,R_\odot$. We speculate that the NS is embedded in the atmosphere of BSDL923 either because it was kicked at birth towards this star or because of inflation of BSDL923 caused by the energy input from the supernova blast wave. Using long-slit spectroscopy with SALT, we searched for possible signs of the SNR shell in the 2D spectrum, but did not find them. This lack of detection is consistent with the young age of this SNR, implying that it is still in the adiabatic phase.
Measurement of the scaling slope of compressible magnetohydrodynamic turbulence by synchrotron radiation statistics
Authors: Zhang Xue-Wen , Zhang Jian-Fu , Wang Ru-Yue , Xiang Fu-Yuan 
Published: June 2023

ABSTRACT
Based on magnetohydrodynamic (MHD) turbulence simulations, we generate synthetic synchrotron observations to explore the scaling slope of the underlying MHD turbulence. We propose the new Q-U cross-intensity X and cross-correlation intensity Y to measure the spectral properties of magnetic turbulence, together with statistics of the traditional synchrotron I and polarization PI intensities. By exploring the statistical behaviour of these diagnostics, we find that the new statistics X and Y can extend the inertial range of turbulence to improve measurement reliability. When focusing on different Alfvénic and sonic turbulence regimes, our results show that the diagnostics proposed in this paper not only reveal the spectral properties of the magnetic turbulence but also gain insight into the individual plasma modes of compressible MHD turbulence. The synergy of multiple statistical methods can extract more reliable turbulence information from the huge amount of observation data from the Low-Frequency Array for radio astronomy and the Square Kilometer Array.
On the formation of GW190521-like binary black hole merger systems
Authors: Cui Zhe , Li Xiang-Dong 
Published: June 2023

ABSTRACT
GW190521 is the most massive merging binary black hole (BBH) system detected so far. At least one of the component BHs was measured to lie within the pair-instability supernova (PISN) mass gap (∼50–135 M⊙), making its formation a mystery. However, the transient observed signal allows alternative posterior distributions. There was suggestion that GW190521 could be an intermediate-mass ratio inspiral, with the component masses m1 ∼ 170 M⊙ and m2 ∼ 16 M⊙, happening to straddle the PISN mass gap. Under this framework, we perform binary population synthesis to explore the formation of GW190521-like systems via isolated binary evolution. We numerically calculate the binding energy parameter for massive stars at different metallicities, and employ them in our calculation for common envelope evolution. Our results prefer that the progenitor binaries formed in metal-poor environment with $\rm Z\le 0.0016$. The predicted merger rate density within redshift z = 1.1 is ${\sim} 4\times 10^{-5}{\text {--}}5\times 10^{-2} \, \rm Gpc^{-3}yr^{-1}$. We expect that such events are potentially observable by upcoming both space and ground-based gravitational wave detectors.
A general framework for removing point-spread function additive systematics in cosmological weak lensing analysis
Authors: Zhang Tianqing , Li Xiangchong , Dalal Roohi , Mandelbaum Rachel , Strauss Michael A , Kannawadi Arun , Miyatake Hironao , Nicola Andrina , Malagón Andrés A Plazas , Shirasaki Masato , Sugiyama Sunao , Takada Masahiro , More Surhud 
Published: June 2023

ABSTRACT
Cosmological weak lensing measurements rely on a precise measurement of the shear two-point correlation function (2PCF) along with a deep understanding of systematics that affect it. In this work, we demonstrate a general framework for detecting and modelling the impact of PSF systematics on the cosmic shear 2PCF and mitigating its impact on cosmological analysis. Our framework can detect PSF leakage and modelling error from all spin-2 quantities contributed by the PSF second and higher moments, rather than just the second moments, using the cross-correlations between galaxy shapes and PSF moments. We interpret null tests using the HSC Year 3 (Y3) catalogs with this formalism and find that leakage from the spin-2 combination of PSF fourth moments is the leading contributor to additive shear systematics, with total contamination that is an order-of-magnitude higher than that contributed by PSF second moments alone. We conducted a mock cosmic shear analysis for HSC Y3 and find that, if uncorrected, PSF systematics can bias the cosmological parameters Ωm and S8 by ∼0.3σ. The traditional second moment-based model can only correct for a 0.1σ bias, leaving the contamination largely uncorrected. We conclude it is necessary to model both PSF second and fourth moment contaminations for HSC Y3 cosmic shear analysis. We also reanalyse the HSC Y1 cosmic shear analysis with our updated systematics model and identify a 0.07σ bias on Ωm when using the more restricted second moment model from the original analysis. We demonstrate how to self-consistently use the method in both real space and Fourier space, assess shear systematics in tomographic bins, and test for PSF model overfitting.
Modelling force-free neutron star magnetospheres using physics-informed neural networks
Authors: Urbán Jorge F , Stefanou Petros , Dehman Clara , Pons José A 
Published: June 2023

ABSTRACT
Using physics-informed neural networks (PINNs) to solve a specific boundary value problem is becoming more popular as an alternative to traditional methods. However, depending on the specific problem, they could be computationally expensive and potentially less accurate. The functionality of PINNs for real-world physical problems can significantly improve if they become more flexible and adaptable. To address this, our work explores the idea of training a PINN for general boundary conditions and source terms expressed through a limited number of coefficients, introduced as additional inputs in the network. Although this process increases the dimensionality and is computationally costly, using the trained network to evaluate new general solutions is much faster. Our results indicate that PINN solutions are relatively accurate, reliable, and well behaved. We applied this idea to the astrophysical scenario of the magnetic field evolution in the interior of a neutron star connected to a force-free magnetosphere. Solving this problem through a global simulation in the entire domain is expensive due to the elliptic solver’s needs for the exterior solution. The computational cost with a PINN was more than an order of magnitude lower than the similar case solved with a finite difference scheme, arguably at the cost of accuracy. These results pave the way for the future extension to three-dimensional of this (or a similar) problem, where generalized boundary conditions are very costly to implement.
Search for superstrong magnetic fields in active processes on the Sun using spectro-polarimetry within 15 Å around the D3 line
Authors: Yakovkin I I , Lozitsky V G 
Published: June 2023

ABSTRACT
We critically review our previous results on this topic based on the following main points: (i) substantially larger wavelength range around the D3 line was investigated – up to ±15 Å instead of ±2.5 Å in comparison with the previous version of our study, and (ii) greater volume of observational data was analysed, including one X limb flare, additionally. Overall, our study concerns the 2004 July 12 active prominence and the 2014 June 10 limb flare of X1.5 class. For named limb flare, we found reliable and oppositely polarized secondary peaks of the V parameter located at distances of −4.5 and +2.7 Å from the line center. If these features are interpreted as manifestations of the magnetic splitting of the line together with its Doppler shift, then the corresponding magnetic field is ≈2.2 × 105 G, and the radial velocity −46 km s−1. Similar spectral manifestations were also found in the active prominence. For comparison with the theory, the spectral features of the Paschen–Baсk effect at magnetic fields up to 100 kG were studied too. It turned out that the theoretical width of the splitting components is relatively small, 0.3 Å, while the width of the observed peaks is sometimes much larger. On the basis of model calculations, it is shown that in some cases an alternative explanation of the observational data is possible, which includes much weaker magnetic fields (5.5–7.1 kG), but significant macroscopic velocities of different signs, at the level of 50–60 km s−1.
The large molecular gas fraction of post-starburst galaxies at z &gt; 1
Authors: Zanella A , Valentino F , Gallazzi A , Belli S , Magdis G , Bolamperti A 
Published: June 2023

ABSTRACT
Post-starburst galaxies are sources that had the last major episode of star formation about 1 Gyr before the epoch of the observations and are on their way to quiescence. It is important to study such galaxies at redshift z &gt; 1, during their main quenching phase, and estimate their molecular gas content to constrain the processes responsible for the cessation of star formation. We present CO(3–2) ALMA observations of two massive (M⋆ ∼ 5 × 1010 M⊙) post-starburst galaxies at z &gt; 1. We measure their molecular gas fraction to be fH2 = MH2/M⋆ ∼ 8–16 per cent, consistent with z &lt; 1 post-starburst galaxies from the literature. The star formation efficiency of our targets is ∼10× lower than that of star-forming galaxies at similar redshift, and they are outliers of the fH2–specific star formation rate (sSFR) relation of star-forming galaxies, as they have larger fH2 than expected given their sSFR. The gas fraction of post-starbursts from our sample and the literature correlates with the Dn4000 spectral index, a proxy of the stellar population age. This suggests that their gas content decreases after the last major burst of star formation. Finally, one of our targets is undergoing a major merger phase with two highly star-forming companions. This hints at a picture where a perturber event (e.g. major merger) quenches star formation without completely removing the molecular gas.
Principal component analysis of galaxy clustering in hyperspace of galaxy properties
Authors: Zhou Shuren , Zhang Pengjie , Chen Ziyang 
Published: June 2023

ABSTRACT
Ongoing and upcoming galaxy surveys are providing precision measurements of galaxy clustering. However, a major obstacle in its cosmological application is the stochasticity in the galaxy bias. We explore whether the principal component analysis (PCA) of galaxy correlation matrix in hyperspace of galaxy properties (e.g. magnitude and colour) can reveal further information on mitigating this issue. Based on the hydrodynamic simulation TNG300-1, we analyse the cross-power spectrum matrix of galaxies in the magnitude and colour space of multiple photometric bands. (1) We find that the first principal component $E_i^{(1)}$ is an excellent proxy of the galaxy deterministic bias bD, in that $E_i^{(1)}=\sqrt{P_{mm}/\lambda ^{(1)}}b_{D,i}$. Here, i denotes the i-th galaxy sub-sample. λ(1) is the largest eigenvalue, and Pmm is the matter power spectrum. We verify that this relation holds for all the galaxy samples investigated, down to k ∼ 2h Mpc−1. Since $E_i^{(1)}$ is a direct observable, we can utilize it to design a linear weighting scheme to suppress the stochasticity in the galaxy–matter relation. For an LSST-like magnitude limit galaxy sample, the stochasticity $\mathcal {S}\equiv 1-r^2$ can be suppressed by a factor of $\gtrsim 2$ at k = 1h Mpc−1. This reduces the stochasticity-induced systematic error in the matter power spectrum reconstruction combining galaxy clustering and galaxy-galaxy lensing from $\sim 12~{{\ \rm per\ cent}}$ to $\sim 5~{{\ \rm per\ cent}}$ at k = 1h Mpc−1. (2) We also find that $\mathcal {S}$ increases monotonically with fλ and $f_{\lambda ^2}$. $f_{\lambda ,\lambda ^2}$ quantify the fractional contribution of other eigenmodes to the galaxy clustering and are direct observables. Therefore, the two provide extra information on mitigating galaxy stochasticity.
Higher water loss on Earth-like exoplanets in eccentric orbits
Authors: Liu Binghan , Marsh Daniel R , Walsh Catherine , Cooke Greg 
Published: June 2023

ABSTRACT
The climate of a terrestrial exoplanet is controlled by the type of host star, the orbital configuration, and the characteristics of the atmosphere and the surface. Many rocky exoplanets have higher eccentricities than those in the Solar system, and about 18 per cent of planets with masses &lt;10 M⊕ have e &gt; 0.1. Underexplored are the implications of such high eccentricities on the atmosphere, climate, and potential habitability on such planets. We use WACCM6, a state-of-the-art fully coupled Earth-system model, to simulate the climates of two Earth-like planets: one in a circular orbit (e = 0), and one in an eccentric orbit (e = 0.4) with the same mean insolation. We quantify the effects of eccentricity on the atmospheric water abundance and loss given the importance of liquid water for habitability. The asymmetric temperature response in the eccentric orbit results in a water vapour mixing ratio in the stratosphere (&gt;20 ppmv) that is approximately five times greater than that for circular orbit (∼4 ppmv). This leads to at most ∼3 times increases in both the atmospheric hydrogen loss rate and the ocean loss rate compared with the circular case. Using the Planetary Spectrum Generator, we simulate the idealized transmission spectra for both cases. We find that the water absorption features are stronger at all wavelengths for the e = 0.4 spectrum than for the circular case. Hence, highly eccentric Earth-like exoplanets may be prime targets for future transmission spectroscopy observations to confirm, or otherwise, the presence of atmospheric water vapour.
Nuclear and electromagnetic cascades induced by ultra-high-energy cosmic rays in radio galaxies: implications for Centaurus A
Authors: Zhang B Theodore , Murase Kohta 
Published: June 2023

ABSTRACT
Very high energy (VHE) γ-rays ($\gtrsim\!\! 0.1\rm ~TeV$) and neutrinos are crucial for identifying accelerators of ultra-high-energy cosmic rays (UHECRs), but this is challenging especially for UHECR nuclei. In this work, we develop a numerical code to solve the transport equation for UHECRs and their secondaries, where both nuclear and electromagnetic cascades are taken into account self-consistently, considering steady UHECR accelerators such as radio galaxies. In particular, we focus on Centaurus A, which has been proposed as one of the most promising UHECR sources in the local Universe. Motivated by observations of extended VHE γ-ray emission from its kiloparsec-scale jet by the High Energy Stereoscopic System (H.E.S.S.), we study interactions between UHECRs accelerated in the large-scale jet and various target photon fields including blazar-like beamed core emission, and present a quantitative study on VHE γ-ray signatures of UHECR nuclei, including the photodisintegration and Bethe–Heitler pair production processes. We show that VHE γ-rays from UHECR nuclei could be detected by the ground-based γ-ray telescopes given that the dominant composition of UHECRs consists of intermediate-mass (such as oxygen) nuclei.
A hot super-Earth planet in the WASP-84 planetary system
Authors: Maciejewski G , Golonka J , Łoboda W , Ohlert J , Fernández M , Aceituno F 
Published: June 2023

ABSTRACT
Hot Jupiters have been perceived as loners devoid of planetary companions in close orbital proximity. However, recent discoveries based on space-borne precise photometry have revealed that at least some fraction of giant planets coexists with low-mass planets in compact orbital architectures. We report detecting a 1.446-d transit-like signal in the photometric time series acquired with the Transiting Exoplanet Survey Satellite (TESS) for the WASP-84 system, which is known to contain a hot Jupiter on a circular 8.5-d orbit. The planet was validated based on TESS photometry, and its signal was distilled in radial velocity measurements. The joint analysis of photometric and Doppler data resulted in a multiplanetary model of the system. With a mass of $15\, \mathrm{ M}_{{\oplus }}$, radius of $2\, \mathrm{ R}_{{\oplus }}$, and orbital distance of 0.024 au, the new planet WASP-84 c was classified as a hot super-Earth with the equilibrium temperature of 1300 K. A growing number of companions to hot Jupiters indicates that a non-negligible part of them must have formed under a quiescent scenario such as disc migration or in situ formation.
Oort cloud (exo)planets
Authors: Raymond Sean N , Izidoro Andre , Kaib Nathan A 
Published: June 2023

ABSTRACT
Dynamical instabilities among giant planets are thought to be nearly ubiquitous and culminate in the ejection of one or more planets into interstellar space. Here, we perform N-body simulations of dynamical instabilities while accounting for torques from the galactic tidal field. We find that a fraction of planets that would otherwise have been ejected are instead trapped on very wide orbits analogous to those of Oort cloud comets. The fraction of ejected planets that are trapped ranges from 1 to 10 per cent, depending on the initial planetary mass distribution. The local galactic density has a modest effect on the trapping efficiency and the orbital radii of trapped planets. The majority of Oort cloud planets survive for Gyr time-scales. Taking into account the demographics of exoplanets, we estimate that one in every 200–3000 stars could host an Oort cloud planet. This value is likely an overestimate, as we do not account for instabilities that take place at early enough times to be affected by their host stars’ birth cluster or planet stripping from passing stars. If the Solar system’s dynamical instability happened after birth cluster dissolution, there is a ∼7 per cent chance that an ice giant was captured in the Sun’s Oort cloud.
Transgenerational Communitarianism in a Global Interconnected World: A Critique
Authors: Bonatti Luigi , Alexandra Lorenzetti Lorenza 
Published: June 2023

Abstract
We discuss how transgenerational communitarianism deals with public decisions involving tradeoffs between different generations’ wellbeing and having global consequences. Policies for tackling climate change are an example. Although there is a natural, evolutionary, basis for intergenerational altruism, most people lack the competencies for constituting a transgenerational community. Moreover, greater attention to future generations’ wellbeing need not substitute for collective action: a lower discount rate reflecting a stronger concern for future generations may even worsen their wellbeing. Finally, in a world of irreducible value pluralism, there is no community of persons sharing moral values that can legitimize common policies for addressing global problems: only the common interest of avoiding destructive consequences may motivate collective action to face problems like climate change.