bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of Arabidopsis phospholipase D δ in regulation of ROS-mediated microtubule organization and stomatal movement upon heat shock
Authors: Song Ping , Jia Qianru , Chen Long , Jin Xin , Xiao Xingkai , Li Li , Chen Huatao , Qu Yana , Su Yinghua , Zhang Wenhua , Zhang Qun 
Published: July 2020

Abstract
Reactive oxygen species (ROS) are plant metabolic and signaling molecules involved in responses to various external stresses, but the existence of ROS receptors and how plants respond to ROS remain largely unknown. Here we report that the plasma membrane-localized phospholipase D δ (PLDδ) protein is crucial for sensing heat shock-induced ROS to initiate reorganization of guard cell microtubules in Arabidopsis cotyledons. Heat shock of wild-type Arabidopsis cotyledons stimulated ROS production which disrupted microtubule organization and induced stomatal closure, whereas this process was markedly impaired in pldδ mutants. Moreover, wild-type PLDδ, but not the Arg622-mutated PLDδ, complemented the pldδ phenotypes in heat shock-treated plants. ROS activated PLDδ by oxidizing cysteine residues, an action that was required for its functions in ROS-induced depolymerization of guard cell microtubules, stomatal closure, and plant thermotolerance. Additionally, lipid profiling reveals involvement of microtubule organization in the feedback regulation of glycerolipid metabolism upon heat stress. Together, our findings highlight a potential mechanosensory role for PLDδ in regulating the dynamic organization of microtubules and stomatal movement, as part of the ROS-sensing pathway, during the response to external stresses.
Searching for eclipsing binaries in the area of RA: 02h21m36s, Dec: +57○11′32″
Authors: Guo Di-Fu , Li Kai , Gao Xing , Gao Dong-Yang , Xu Zhi-Jian , Sun Guo-You , Liu Fen , Zhang Chang-Ming 
Published: July 2020

ABSTRACT
By analysing the data observed by the Comet Search Programme telescope at Xingming Observatory from 2018 October 11 to 2018 December 19, 24 eclipsing binaries were identified. By cross-matching with the VSX (AAVSO) website, we found that four binaries are newly discovered. By analysing the Transiting Exoplanet Survey Satellite (TESS) data, the light curves of 17 binaries were obtained. First photometric solutions of 23 binaries were obtained by simultaneously analysing all the light curves, except for NSVS 1908107 (first analysed by Pan et al.). Based on the photometric solutions, nine binaries belong to detached binary systems, ten binaries belong to semidetached binary systems, and five binaries belong to contact binary systems. Two W-subtype low-mass ratio contact binaries (the less massive components are hotter), with total eclipsing light curves, were identified: Mis V1395 is a deep contact binary (q = 0.150, $f=80{{\ \rm per\ cent}}$), while NSVS 1917038 is a low-mass ratio binary with an unexpectedly marginal contact degree (q = 1/6.839 = 0.146, $f=4{{\ \rm per\ cent}}$). The total eclipsing detached binary GSC 03698-00022 has an extremely low mass ratio of q = 0.085. The Algol-type binary NSVS 1908107 is also found to have an extremely low mass ratio of q = 0.081. The Algol-type binary DK Per exhibits a continuous period decrease at a rate of dP/dt = −1.26 × 10−7 d yr−1, which may result from the orbital angular momentum loss. Based on the light curves obtained from the TESS data, a pulsating binary candidate (NSVS 1913053) was found.
The effect of the slit configuration on the H2 1-0 s(1) to Br γ line ratio of spatially resolved planetary nebulae
Authors: Aleman Isabel 
Published: July 2020

ABSTRACT
The H2 1-0 S(1)/Br γ ratio (R(Br γ)) is used in many studies of the molecular content in planetary nebulae (PNe). As these lines are produced in different regions, the slit configuration used in spectroscopic observations may have an important effect on their ratio. In this work, observations and numerical simulations are used to demonstrate and quantify such effect in PNe. The study aims to assist the interpretation of observations and their comparison to models. The analysis shows that observed R(Br γ) ratios reach only values up to 0.3 when the slit encompasses the entire nebula. Values higher than that are only obtained when the slit covers a limited region around the H2 peak emission and the Br γ emission is then minimized. The numerical simulations presented show that, when the effect of the slit configuration is taken into account, photoionization models can reproduce the whole range of observed R(Br γ) in PNe, as well as the behaviour described above. The argument that shocks are needed to explain the higher values of R(Br γ) is thus not valid. Therefore, this ratio is not a good indicator of the H2 excitation mechanism as suggested in the literature.
Spiral density enhancements in Be binary systems
Authors: Cyr Isabelle H , Jones C E , Carciofi A C , Steckel C , Tycner C , Okazaki A T 
Published: July 2020

ABSTRACT
We use a smoothed particle hydrodynamics (SPH) code to examine the effects of a binary companion on a Be star disc for a range of disc viscosities and misalignment angles, i.e. the angle between the orbital plane and the primary star’s spin axis. The density structures in the disc due to the tidal interaction with the binary companion are investigated. Expanding on our previous work, the shape and density structure of density enhancements due to the binary companion are analysed and the changes in observed interferometric features due to these orbiting enhancements are also predicted. We find that larger misalignment angles and viscosity values result in more tightly wound spiral arms with densities that fall-off more slowly with radial distance from the central star. We show that the orbital phase has very little effect on the structure of the spiral density enhancements. We demonstrate that these spiral features can be detected with an interferometer in H α and K-band emission. We also show that the spiral features affect the axis ratios determined by interferometry depending on the orientation of these features and the observer. For example, our simulations show that the axis ratios can vary by 20 per cent for our co-planar binary disc system depending on the location of the disc density enhancements.
Improving position accuracy for telescopes with small aperture and wide field of view utilizing point spread function modelling
Authors: Sun Rongyu , Yu Shengxian , Jia Peng , Zhao Changyin 
Published: July 2020

ABSTRACT
Telescopes with a small aperture and a wide field of view are widely used and play a significant role in large-scale state-of-the-art sky survey applications, such as transient detection and near-Earth object observations. However, owing to the specific defects caused by optical aberrations, the image quality and efficiency of source detection are affected. To achieve high-accuracy position measurements, an innovative technique is proposed. First, a large number of raw images are analysed using principal component analysis. Then, the effective point spread function is reconstructed, which reflects the state of the telescope and reveals the characteristics of the imaging process. Finally, based on the point spread function model, the centroids of star images are estimated iteratively. To test the efficiency and reliability of our algorithm, a large number of simulated images are produced, and a telescope with small aperture and wide field of view is utilized to acquire the raw images. The position measurement of sources is performed using our novel method and two other common methods on these data. Based on a comparison of the results, the improvement is investigated, and it is demonstrated that our proposed technique outperforms the others on position accuracy. We explore the limitations and potential gains that may be achieved by applying this technique to custom systems designed specifically for wide-field astronomical applications.
Cosmological constraints from H ii starburst galaxy apparent magnitude and other cosmological measurements
Authors: Cao Shulei , Ryan Joseph , Ratra Bharat 
Published: July 2020

ABSTRACT
We use H ii starburst galaxy apparent magnitude measurements to constrain cosmological parameters in six cosmological models. A joint analysis of H ii galaxy, quasar angular size, baryon acoustic oscillations peak length scale, and Hubble parameter measurements result in relatively model-independent and restrictive estimates of the current values of the non-relativistic matter density parameter $\Omega _{\rm m_0}$ and the Hubble constant H0. These estimates favour a 2.0–3.4σ (depending on cosmological model) lower H0 than what is measured from the local expansion rate. The combined data are consistent with dark energy being a cosmological constant and with flat spatial hypersurfaces, but do not strongly rule out mild dark energy dynamics or slightly non-flat spatial geometries.
PTF11rka: an interacting supernova at the crossroads of stripped-envelope and H-poor superluminous stellar core collapses
Authors: Pian E , Mazzali P A , Moriya T J , Rubin A , Gal-Yam A , Arcavi I , Ben-Ami S , Blagorodnova N , Bufano F , Filippenko A V , Kasliwal M , Kulkarni S R , Lunnan R , Manulis I , Matheson T , Nugent P E , Ofek E , Perley D A , Prentice S J , Yaron O 
Published: July 2020

ABSTRACT
The hydrogen-poor supernova (SN) PTF11rka (z = 0.0744), reported by the Palomar Transient Factory, was observed with various telescopes starting a few days after the estimated explosion time of 2011 December 5 UT and up to 432 rest-frame days thereafter. The rising part of the light curve was monitored only in the RPTF filter band, and maximum in this band was reached ∼30 rest-frame days after the estimated explosion time. The light curve and spectra of PTF11rka are consistent with the core-collapse explosion of a ∼10 M⊙ carbon–oxygen core evolved from a progenitor of main-sequence mass 25–40 M⊙, that liberated a kinetic energy Ek≈4 × 1051 erg, expelled ∼8 M⊙ of ejecta, and synthesized ∼0.5 M⊙ of 56Ni. The photospheric spectra of PTF11rka are characterized by narrow absorption lines that point to suppression of the highest ejecta velocities (≳ 15 000 km s−1). This would be expected if the ejecta impacted a dense, clumpy circumstellar medium. This in turn caused them to lose a fraction of their energy (∼5 × 1050 erg), less than 2 per cent of which was converted into radiation that sustained the light curve before maximum brightness. This is reminiscent of the superluminous SN 2007bi, the light-curve shape and spectra of which are very similar to those of PTF11rka, although the latter is a factor of 10 less luminous and evolves faster in time. PTF11rka is in fact more similar to gamma-ray burst SNe in luminosity, although it has a lower energy and a lower Ek/Mej ratio.
Resonant-line radiative transfer within power-law density profiles
Authors: Lao Bing-Xin , Smith Aaron 
Published: July 2020

ABSTRACT
Star-forming regions in galaxies are surrounded by vast reservoirs of gas capable of both emitting and absorbing Lyman α (Lyα) radiation. Observations of Lyα emitters and spatially extended Lyα haloes indeed provide insights into the formation and evolution of galaxies. However, due to the complexity of resonant scattering, only a few analytic solutions are known in the literature. We discuss several idealized but physically motivated scenarios to extend the existing formalism to new analytic solutions, enabling quantitative predictions about the transport and diffusion of Lyα photons. This includes a closed form solution for the radiation field and derived quantities including the emergent flux, peak locations, energy density, average internal spectrum, number of scatters, outward force multiplier, trapping time, and characteristic radius. To verify our predictions, we employ a robust gridless Monte Carlo radiative transfer (GMCRT) method, which is straightforward to incorporate into existing ray tracing codes but requires modifications to opacity-based calculations, including dynamical core-skipping acceleration schemes. We primarily focus on power-law density and emissivity profiles, however both the analytic and numerical methods can be generalized to other cases. Such studies provide additional intuition and understanding regarding the connection between the physical environments and observational signatures of galaxies throughout the Universe.
Exploring AGN and star formation activity of massive galaxies at cosmic noon
Authors: Florez Jonathan , Jogee Shardha , Sherman Sydney , Stevans Matthew L , Finkelstein Steven L , Papovich Casey , Kawinwanichakij Lalitwadee , Ciardullo Robin , Gronwall Caryl , Urry C Megan , Kirkpatrick Allison , LaMassa Stephanie M , Ananna Tonima Tasnim , Wold Isak 
Published: July 2020

ABSTRACT
We investigate the relation between active galactic nucleus (AGN) and star formation (SF) activity at 0.5 &lt; z &lt; 3 by analysing 898 galaxies with X-ray luminous AGNs (LX &gt; 1044 erg s−1) and a large comparison sample of ∼320 000 galaxies without X-ray luminous AGNs. Our samples are selected from a large (11.8 deg2) area in Stripe 82 that has multiwavelength (X-ray to far-IR) data. The enormous comoving volume (∼0.3 Gpc3) at 0.5 &lt; z &lt; 3 minimizes the effects of cosmic variance and captures a large number of massive galaxies (∼30 000 galaxies with M* &gt; 1011 M⊙) and X-ray luminous AGNs. While many galaxy studies discard AGN hosts, we fit the SED of galaxies with and without X-ray luminous AGNs with Code Investigating GALaxy Emission and include AGN emission templates. We find that without this inclusion, stellar masses and star formation rates (SFRs) in AGN host galaxies can be overestimated, on average, by factors of up to ∼5 and ∼10, respectively. The average SFR of galaxies with X-ray luminous AGNs is higher by a factor of ∼3–10 compared to galaxies without X-ray luminous AGNs at fixed stellar mass and redshift, suggesting that high SFRs and high AGN X-ray luminosities may be fuelled by common mechanisms. The vast majority ($\gt 95 {{\ \rm per\ cent}}$) of galaxies with X-ray luminous AGNs at z = 0.5−3 do not show quenched SF: this suggests that if AGN feedback quenches SF, the associated quenching process takes a significant time to act and the quenched phase sets in after the highly luminous phases of AGN activity.
A complete view of the outskirts of the Coma cluster
Authors: Mirakhor M S , Walker S A 
Published: July 2020

ABSTRACT
We present a new extended XMM–Newton mosaic of the nearby Coma cluster, which covers the cluster out to the virial radius with nearly complete azimuthal coverage. This large mosaic is combined with the Planck Sunyaev Zel’dovich effect observations to recover the thermodynamic properties of the intracluster medium in an azimuthally averaged profile and 36 angular sectors, producing the highest spatial resolution view of the thermodynamics of the outskirts of a galaxy cluster in its entirety. Beyond r500, our clumping-corrected entropy measurements along the less disturbed directions are statistically consistent with the power-law entropy profile predicted by non-radiative simulations, and the gas mass fraction agrees with the mean cosmic baryon fraction. However, there is a clear entropy deficit in the outskirts to the south-west, coinciding with where Coma connects to a cosmic web filament that joins it to Abell 1367. The low entropy to the south-west extends from 0.5 to 1.0r200, and is consistent with what is expected from simulations of a filamentary gas stream penetrating into the cluster as it continues to accrete matter from the cosmic web. We also find that the radial profiles of the recovered quantities become increasingly asymmetric in the outskirts, particularly along the more disturbed directions, consistent with the predictions of cosmological simulations.
A high coverage view of the thermodynamics and metal abundance in the outskirts of the nearby galaxy cluster Abell 2199
Authors: Mirakhor M S , Walker S A 
Published: July 2020

ABSTRACT
We present a joint Suzaku and XMM–Newton analysis of the outskirts of the nearby galaxy cluster Abell 2199, the only nearby galaxy cluster to be observed with near complete azimuthal coverage with Suzaku. Using the XMM–Newton observations to correct for the effects of gas clumping, we find that the azimuthally averaged entropy profile in the outskirts follows a power law with a slope of 1.20 ± 0.23, statistically consistent with a slope of 1.1 predicted by non-radiative simulations for purely gravitational hierarchical structure formation. However, when divided into 10 sectors, the entropy shows significant azimuthal variation, with some sectors lying below the baseline level. The azimuthally averaged gas mass fraction is found to agree with the cosmic mean baryon fraction. The metal abundance in the outskirts is found to be consistent with being uniform in all directions and it has an average value of $0.29_{-0.03}^{+0.03}\, \mathrm{ Z}_{\odot }$, consistent with the gas accreting on to clusters being pre-enriched with metals.
The landscape of disc outflows from black hole–neutron star mergers
Authors: Fernández Rodrigo , Foucart Francois , Lippuner Jonas 
Published: July 2020

ABSTRACT
We investigate mass ejection from accretion discs formed in mergers of black holes (BHs) and neutron stars (NSs). The third observing run of the LIGO/Virgo interferometers provided BH–NS candidate events that yielded no electromagnetic (EM) counterparts. The broad range of disc configurations expected from BH–NS mergers motivates a thorough exploration of parameter space to improve EM signal predictions. Here we conduct 27 high-resolution, axisymmetric, long-term hydrodynamic simulations of the viscous evolution of BH accretion discs that include neutrino emission/absorption effects and post-processing with a nuclear reaction network. In the absence of magnetic fields, these simulations provide a lower limit to the fraction of the initial disc mass ejected. We find a nearly linear inverse dependence of this fraction on disc compactness (BH mass over initial disc radius). The dependence is related to the fraction of the disc mass accreted before the ouflow is launched, which depends on the disc position relative to the innermost stable circular orbit. We also characterize a trend of decreasing ejected fraction and decreasing lanthanide/actinide content with increasing disc mass at fixed BH mass. This trend results from a longer time to reach weak freezout and an increasingly dominant role of neutrino absorption at higher disc masses. We estimate the radioactive luminosity from the disc outflow alone available to power kilonovae over the range of configurations studied, finding a spread of two orders of magnitude. For most of the BH–NS parameter space, the disc outflow contribution is well below the kilonova mass upper limits for GW190814.
High-accuracy short-term precipitable water-vapour operational forecast at the Very Large Telescope and perspectives for sky background forecast
Authors: Turchi A , Masciadri E , Pathak P , Kasper M 
Published: July 2020

ABSTRACT
In this article, we present the first results ever obtained by applying the autoregressive (AR) technique to precipitable water vapour (PWV). The study is performed at the Very Large Telescope (VLT). The AR technique was proposed recently to provide forecasts of atmospheric and astroclimatic parameters on short time-scales (up to a few hours) by achieving much better performance with respect to the ‘standard forecasts’ provided in early afternoon for the coming night. The AR method uses real-time measurements of the parameter of interest to improve the forecasts performed with atmospherical models. Here, we used measurements provided by the Low Humidity And Temperature PROfiling microwave radiometer (LHATPRO), a radiometer measuring the PWV at the VLT continuously. When comparing the AR forecast at 1h with the standard forecast, we observe a gain factor of ∼8 (i.e. ∼800 per cent) in terms of forecast accuracy. In the PWV ≤ 1 mm range, which is extremely critical for infrared astronomical applications, the RMSE of the predictions is of the order of just a few hundredth of millimetres (0.04 mm). We therefore proved that the AR technique provides an important benefit to VLT science operations for all instruments sensitive to PWV. Also, we show how such an ability to predict PWV can also be useful to predict the sky background in the infrared range [extremely appealing for Mid-infrared ELT Imager and Spectrograph (METIS)]. We quantify such an ability by applying this method to the New Earth in the Alpha Cen region (NEAR) project supported by the European Southern Observatory (ESO) and Breakthrough Initiatives.
Deflection of the hypervelocity stars by the pull of the Large Magellanic Cloud on the Milky Way
Authors: Boubert D , Erkal D , Gualandris A 
Published: July 2020

ABSTRACT
Stars slingshotted by the supermassive black hole at the Galactic Centre escape from the Milky Way so quickly that their trajectories are almost straight lines. Previous works have shown how these ‘hypervelocity stars’ (stars moving faster than the local Galactic escape speed) are subsequently deflected by the gravitational field of the Milky Way and the Large Magellanic Cloud (LMC), but have neglected to account for the reflex motion of the Milky Way in response to the fly-by of the LMC. A consequence of this motion is that the hypervelocity stars we see in the outskirts of the Milky Way today were ejected from where the Milky Way centre was hundreds of millions of years ago. This change in perspective causes large apparent deflections of several degrees in the trajectories of the hypervelocity stars. We quantify these deflections by simulating the ejection of hypervelocity stars from an isolated Milky Way (with a spherical or flattened dark matter halo), from a fixed-in-place Milky Way with a passing LMC, and from a Milky Way that responds to the passage of the LMC, finding that LMC passage causes larger deflections than can be caused by a flattened Galactic dark matter halo in ΛCDM. The $10\, \mu \mathrm{as}\, \mathrm{yr}^{-1}$ proper motion precision necessary to measure these deflections will be possible with the combination of Gaia with the proposed GaiaNIR successor mission, and these measurements will directly probe the shape of the Milky Way, the mass of the LMC, and the dance of these two galaxies.
A chemical study of carbon fractionation in external galaxies
Authors: Viti Serena , Fontani Francesco , Jiménez-Serra Izaskun 
Published: July 2020

ABSTRACT
In the interstellar medium carbon exists in the form of two stable isotopes 12C and 13C and their ratio is a good indicator of nucleosynthesis in galaxies. However, chemical fractionation can potentially significantly alter this ratio and in fact observations of carbon fractionation within the same galaxy has been found to vary from species to species. In this paper, we theoretically investigate the carbon fractionation for selected abundant carbon-bearing species in order to determine the conditions that may lead to a spread of the 12C/13C ratio in external galaxies. We find that carbon fractionation is sensitive to almost all the physical conditions we investigated, it strongly varies with time for all species but CO, and shows pronounced differences across species. Finally, we discuss our theoretical results in the context of the few observations of the 12C/13C  in both local and higher redshift galaxies.