914 results on '"F500"'
Search Results
2. Foliar application of pyraclostrobin alleviates oxidative stress and improves carbon assimilation in soybean
- Author
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Juhie Joshi-Paneri, Sonika Sharma, and Kadur Narayan Guruprasad
- Subjects
biomass ,f500 ,glycine max ,antioxidant enzymes ,photosynthesis ,strobilurin ,Agriculture (General) ,S1-972 - Abstract
Due to its protein and oil content, soybean is an important crop in developing countries like India to combat energy-protein malnutrition. In a field study, soybean plants- foliar treated with pyraclostrobin- were evaluated for carbon fixation efficiency and antioxidant levels response. Pyraclostrobin (F500) was sprayed over soybean leaves on the tenth and twentieth day after the emergence (DAE) of seedlings at concentrations ranging from 0.05% to 1%. Parameters associated with carbon fixation, like photosystem II efficiency, gas exchange parameters, carbonic anhydrase activity, and biomass accumulation, were quantified on the 45th DAE. Antioxidant level and activity of antioxidant enzymes were also analyzed at the same stage. The amount of antioxidants like ascorbate (ASA) and the activity of antioxidant enzymes (i.e., guaiacol peroxidase, ascorbic acid peroxidase, superoxide dismutase, and catalase) decreased after pyraclostrobin application indicating alleviation of oxidative stress in treated plants as compared to control. A significant increase in the rate of photosynthesis was also recorded in the treated plants. Limiting factors of net photosynthesis like chlorophyll content, carbonic anhydrase activity, stomatal conductance, inter-cellular CO 2 concentration, and transpiration rate improved after 0.1% F500 treatment. Mitigation of oxidative stress by pyraclostrobin improves the primary metabolism (fixation) in soybean, resulting in enhanced biomass accumulation.
- Published
- 2023
- Full Text
- View/download PDF
3. Foliar application of pyraclostrobin alleviates oxidative stress and improves carbon assimilation in soybean.
- Author
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Joshi-Paneri, Juhie, Sharma, Sonika, and Guruprasad, Kadur Narayan
- Abstract
Due to its protein and oil content, soybean is an important crop in developing countries like India to combat energy-protein malnutrition. In a field study, soybean plants- foliar treated with pyraclostrobin- were evaluated for carbon fixation efficiency and antioxidant levels response. Pyraclostrobin (F500) was sprayed over soybean leaves on the tenth and twentieth day after the emergence (DAE) of seedlings at concentrations ranging from 0.05% to 1%. Parameters associated with carbon fixation, like photosystem II efficiency, gas exchange parameters, carbonic anhydrase activity, and biomass accumulation, were quantified on the 45th DAE. Antioxidant level and activity of antioxidant enzymes were also analyzed at the same stage. The amount of antioxidants like ascorbate (ASA) and the activity of antioxidant enzymes (i.e., guaiacol peroxidase, ascorbic acid peroxidase, superoxide dismutase, and catalase) decreased after pyraclostrobin application indicating alleviation of oxidative stress in treated plants as compared to control. A significant increase in the rate of photosynthesis was also recorded in the treated plants. Limiting factors of net photosynthesis like chlorophyll content, carbonic anhydrase activity, stomatal conductance, inter-cellular CO2 concentration, and transpiration rate improved after 0.1% F500 treatment. Mitigation of oxidative stress by pyraclostrobin improves the primary metabolism (fixation) in soybean, resulting in enhanced biomass accumulation. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. GC Insights: Space sector careers resources in the UK need a greater diversity of roles
- Author
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Martin O. Archer, Cara L. Waters, Shafiat Dewan, Simon Foster, Antonio Portas, Engineering & Physical Science Research Council (EPSRC), UKRI, and Science and Technology Facilities Council
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ComputingMilieux_THECOMPUTINGPROFESSION ,Physics Education (physics.ed-ph) ,N600 ,Physics - Physics Education ,physics.ed-ph ,physics.pop-ph ,ComputingMilieux_COMPUTERSANDEDUCATION ,FOS: Physical sciences ,F500 ,Popular Physics (physics.pop-ph) ,Physics - Popular Physics - Abstract
Educational research highlights that improved careers education is needed to increase participation in science, technology, engineering, and mathematics (STEM). Current UK careers resources concerning the space sector, however, are found to perhaps not best reflect the diversity of roles present and may in fact perpetuate misconceptions about the usefulness of science. We, therefore, compile a more diverse set of space-related jobs, which will be used in the development of a new space careers resource.
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- 2022
5. Taxonomy of protoplanetary discs observed with ALMA
- Author
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Parker, Raeesa, Ward-Thompson, Derek, and Kirk, Jason Matthew
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Space and Planetary Science ,Astronomy and Astrophysics ,F500 - Abstract
Many observations of protoplanetary discs studied with ALMA have revealed the complex substructure present in the discs. Rings and gaps in the dust continuum are now a common sight in many discs; however, their origins still remain unknown. We look at all protoplanetary disc images taken with ALMA from cycles 0 to 5 and find that 56 discs show clear substructure. We further study the 56 discs and classify the morphology seen according to four categories: Rim, Ring, Horseshoe, and Spiral. We calculate the ages of the host stars using stellar isochrones and investigate the relation between the morphology of the substructure seen in the protoplanetary discs and the age of the host stars. We find that there is no clear evolutionary sequence in the protoplanetary discs as the stars increase in age, although there is a slight tendency for spirals to appear in younger systems and horseshoes to be seen in more evolved systems. We also show that majority of the images of protoplanetary discs made by ALMA may not have had a sufficiently high resolution or sensitivity to resolve substructure in the disc. We show that angular resolution is important in detecting substructure within protoplanetary discs, with sensitivity distinguishing between the different types of substructure. We compare the substructure seen in protoplanetary discs at sub-mm to those seen in scattered light. We find that cavities are a common substructure seen in discs at both sub-mm wavelengths and in scattered light.
- Published
- 2022
6. Stellar rotation rates in Kepler eccentric (heartbeat) binaries obtained from r-mode signatures
- Author
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Saio, Hideyuki and Kurtz, Donald Wayne
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Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,FOS: Physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astronomy and Astrophysics ,F500 ,Astrophysics::Earth and Planetary Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
R-mode oscillations in a rotating star produce characteristic signatures in a Fourier amplitude spectrum at frequencies related with the rotation frequency, which can be, in turn, used to obtain the surface rotation rate of the star. Some binary stars observed by Kepler indicate the presence of r~modes that are probably excited by the tidal effect. In this paper, we have obtained stellar rotation periods in 20 eccentric (heartbeat) binaries with r-mode signatures. The majority of the rotation periods are found to be comparable to pseudo-synchronous periods, in which the angular velocity of rotation is similar to the angular orbital motion of the companion at periastron. In particular, for the heartbeat stars with orbital periods longer than about 8\,d, all but one agree with pseudo-synchronous rotation. In contrast to a previous investigation by Zimmerman et al., our result supports the pseudo-synchronisation theory developed by Hut., Comment: 13 pages, to appear in MNRAS
- Published
- 2022
7. The diverse nature and formation paths of slow rotator galaxies in the <scp>eagle</scp> simulations
- Author
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Eric Emsellem, Ruby J. Wright, Thomas A. Davison, Caroline Foster, K. E. Harborne, Claudia del P. Lagos, Jesse van de Sande, Luca Cortese, Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Active galactic nucleus ,Field (physics) ,FOS: Physical sciences ,F500 ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Prolate spheroid ,Astrophysics ,Galaxy merger ,01 natural sciences ,Physics::Plasma Physics ,0103 physical sciences ,galaxies: formation ,Connection (algebraic framework) ,10. No inequality ,010303 astronomy & astrophysics ,galaxies: kinematics and dynamics ,Astrophysics::Galaxy Astrophysics ,Physics ,010308 nuclear & particles physics ,Velocity dispersion ,Astronomy and Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,[SDU]Sciences of the Universe [physics] ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,galaxies: structure ,galaxies: evolution - Abstract
We use a sample of $z=0$ galaxies visually classified as slow rotators (SRs) in the EAGLE hydrodynamical simulations to explore the effect of galaxy mergers on their formation, characterise their intrinsic galaxy properties, and study the connection between quenching and kinematic transformation. SRs that have had major or minor mergers (mass ratios $\ge 0.3$ and $0.1-0.3$, respectively) tend to have a higher triaxiality parameter and ex-situ stellar fractions than those that had exclusively very minor mergers or formed in the absence of mergers ("no-merger" SRs). No-merger SRs are more compact, have lower black hole-to-stellar mass ratios and quenched later than other SRs, leaving imprints on their $z=0$ chemical composition. For the vast majority of SRs we find that quenching, driven by active galactic nuclei feedback, precedes kinematic transformation, except for satellite SRs, in which these processes happen in tandem. However, in $\approx 50$\% of these satellites, satellite-satellite mergers are responsible for their SR fate, while environment (i.e. tidal field and interactions with the central) can account for the transformation in the rest. By splitting SRs into kinematic sub-classes, we find that flat SRs prefer major mergers; round SRs prefer minor or very minor mergers; prolate SRs prefer gas-poor mergers. Flat and prolate SRs are more common among satellites hosted by massive halos ($>10^{13.6}\,\rm M_{\odot}$) and centrals of high masses ($M_{\star} > 10^{10.5}\, \rm M_{\odot}$). Although EAGLE galaxies display kinematic properties that broadly agree with observations, there are areas of disagreement, such as inverted stellar age and velocity dispersion profiles. We discuss these and how upcoming simulations can solve them., Accepted for publications in MNRAS. 22 pages and 20 figures. Main difference with previous version is additional panel in Fig. 7 showing Sersic index vs stellar mass for different merger histories
- Published
- 2021
8. Response timescales of the magnetotail current sheet during a geomagnetic storm: Global MHD simulations
- Author
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Eggington, J, Coxon, J, Shore, R, Desai, R, Mejnertsen, L, Chittenden, J, Eastwood, J, Natural Environment Research Council (NERC), and Science and Technology Facilities Council
- Subjects
Astronomy and Astrophysics ,F500 - Abstract
The response of the Earth’s magnetotail current sheet to the external solar wind driver is highly time-dependent and asymmetric. For example, the current sheet twists in response to variations in the By component of the interplanetary magnetic field (IMF), and is hinged by the dipole tilt. Understanding the timescales over which these asymmetries manifest is of particular importance during geomagnetic storms when the dynamics of the tail control substorm activity. To investigate this, we use the Gorgon MHD model to simulate a geomagnetic storm which commenced on 3 May 2014, and was host to multiple By and Bz reversals and a prolonged period of southward IMF driving. We find that the twisting of the current sheet is well-correlated to IMF By throughout the event, with the angle of rotation increasing linearly with downtail distance and being more pronounced when the tail contains less open flux. During periods of southward IMF the twisting of the central current sheet responds most strongly at a timelag of ∼ 100 min for distances beyond 20 RE, consistent with the 1–2 h convection timescale identified in the open flux content. Under predominantly northward IMF the response of the twisting is bimodal, with the strongest correlations between 15 and 40 RE downtail being at a shorter timescale of ∼ 30 min consistent with that estimated for induced By due to wave propagation, compared to a longer timescale of ∼ 3 h further downtail again attributed to convection. This indicates that asymmetries in the magnetotail communicated by IMF By are influenced mostly by global convection during strong solar wind driving, but that more prompt induced By effects can dominate in the near-Earth tail and during periods of weaker driving. These results provide new insight into the characteristic timescales of solar wind-magnetosphere-ionosphere coupling.
- Published
- 2022
9. Statistical investigation on equatorial pitch angle distribution of energetic electrons in Earth’s outer radiation belt during CME- and CIR-driven storms
- Author
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Chakraborty, Suman, Chakrabarty, Dibyendu, Reeves, Geoffrey D., Baker, Daniel N., and Rae, Jonathan
- Subjects
F300 ,Astronomy and Astrophysics ,F500 - Abstract
We present a statistical investigation (September 2012 - September 2017) of pitch angle distribution (PAD) of energetic electrons (∼30 keV - 1 MeV) in the outer radiation belt (L ≥ 3) during CME- and CIR-driven geomagnetic storms using Van Allen Probe measurements. We selected geomagnetic storms based on minimum of SYM-H being less than -50 nT and classified the storms according to their drivers. Thus, we obtained 23 CME- and 24 CIR-driven storms. During the storm intervals, pitch angle resolved electron flux measurements are obtained from the MagEIS instrument on-board Van Allen Probe-A spacecraft. We assume symmetric pitch angle distributions around 90° pitch angle and fit the observed PADs with Legendre polynomials after propagating them to the magnetic equator. Legendre coefficients c2 and c4, and the ratio R = |c2/c4| are used to categorize the different PAD types. To resolve the spatio-temporal distribution of PADs, these coefficients are binned in 5 L-shell bins, 12 MLT bins for seven energy channels and four storm phases. We found that several hundreds of keV electrons exhibit clear dependence on local time, storm phases and storm drivers, with increased anisotropy for CME-driven storms during main and early recovery phases. On the contrary, we found that tens of keV electrons do not exhibit significant dependence on these parameters. We have discussed the different physical mechanisms responsible for the observed MLT dependent PADs and found drift-shell splitting to be the major contributor.
- Published
- 2022
10. On the application of machine learning in astronomy and astrophysics: A text‐mining‐based scientometric analysis
- Author
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José‐Víctor Rodríguez, Ignacio Rodríguez‐Rodríguez, and Wai Lok Woo
- Subjects
Text mining ,General Computer Science ,Astronomy ,G400 ,Machine learning ,Scientometrics ,F500 ,G700 ,Astrophysics - Abstract
Since the beginning of the 21st century, the fields of astronomy and astrophysics have experienced significant growth at observational and computational levels, leading to the acquisition of increasingly huge volumes of data. In order to process this vast quantity of information, artificial intelligence (AI) techniques are being combined with data mining to detect patterns with the aim of modeling, classifying or predicting the behavior of certain astronomical phenomena or objects. Parallel to the exponential development of the aforementioned techniques, the scientific output related to the application of AI and machine learning (ML) in astronomy and astrophysics has also experienced considerable growth in recent years. Therefore, the increasingly abundant articles make it difficult to monitor this field in terms of which research topics are the most prolific or novel, or which countries or authors are leading them. In this article, a text-mining-based scientometric analysis of scientific documents published over the last three decades on the application of AI and ML in the fields of astronomy and astrophysics is presented. The VOSviewer software and data from the Web of Science (WoS) are used to elucidate the evolution of publications in this research field, their distribution by country (including co-authorship), the most relevant topics addressed, and the most cited elements and most significant co-citations according to publication source and authorship. The obtained results demonstrate how application of AI/ML to the fields of astronomy/astrophysics represents an established and rapidly growing field of research that is crucial to obtaining scientific understanding of the universe.
- Published
- 2022
11. Direct Evidence of Magnetic Reconnection Onset via the Tearing Instability
- Author
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Mayur R. Bakrania, I. Jonathan Rae, Andrew P. Walsh, Daniel Verscharen, Andy W. Smith, Colin Forsyth, and Anna Tenerani
- Subjects
Plasma Physics (physics.plasm-ph) ,Physics::Plasma Physics ,F300 ,Physics::Space Physics ,FOS: Physical sciences ,Astronomy and Astrophysics ,F500 ,Physics - Plasma Physics - Abstract
Magnetic reconnection is a sporadic process responsible for energy release in space and laboratory plasmas. It is believed that the tearing mode instability may be responsible for the onset of reconnection in the magnetotail. However, due to its elusive nature, there is an absence of in-situ observations of the tearing instability prior to magnetic reconnection in our nearest natural plasma laboratory. Using neural network outlier detection methods in conjunction with Cluster spacecraft data, we find unique electron pitch angle distributions that are consistent with simulation predictions of the tearing instability and the subsequent evolution of plasma electrons and reconnection. We evaluate tearing stability criterion for the events identified via our neural network outlier method, and find signatures of magnetic reconnection minutes after the majority of tearing observations. Our analysis of the tearing instability provides new insights into the fundamental understanding of the mechanism responsible for reconnection, a process that is ubiquitous in different astrophysical plasma regimes across the Universe and in laboratory experiments on Earth.
- Published
- 2022
12. The independence of oscillatory reconnection periodicity from the initial pulse
- Author
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Gert Botha, Stephane Regnier, James McLaughlin, and Konstantinos Karampelas
- Subjects
MHD WAVE-PROPAGATION ,PULSATIONS ,Science & Technology ,F300 ,FOS: Physical sciences ,Astronomy and Astrophysics ,F500 ,Astronomy & Astrophysics ,NULL POINTS ,STELLAR FLARES ,SOLAR CORONA ,NEIGHBORHOOD ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,MAGNETIC RECONNECTION ,Physics::Space Physics ,Physical Sciences ,Astrophysics::Solar and Stellar Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,X-POINT ,2D ,GENERATION - Abstract
Oscillatory reconnection can manifest through the interaction between the ubiquitous MHD waves and omnipresent null points in the solar atmosphere and is characterized by an inherent periodicity. In the current study, we focus on the relationship between the period of oscillatory reconnection and the strength of the wave pulse initially perturbing the null point, in a hot coronal plasma. We use the PLUTO code to solve the fully compressive, resistive MHD equations for a 2D magnetic X-point. Using wave pulses with a wide range of amplitudes, we perform a parameter study to obtain values for the period, considering the presence and absence of anisotropic thermal conduction separately. In both cases, we find that the resulting period is independent of the strength of the initial perturbation. The addition of anisotropic thermal conduction only leads to an increase in the mean value for the period, in agreement with our previous study. We also consider a different type of initial driver and we obtain an oscillation period matching the independent trend previously mentioned. Thus, we report for the first time on the independence between the type and strength of the initializing wave pulse and the resulting period of oscillatory reconnection in a hot coronal plasma. This makes oscillatory reconnection a promising mechanism to be used within the context of coronal seismology., 19 pages, 14 figures, accepted for publication in ApJ
- Published
- 2022
13. Automatic detection of small-scale EUV brightenings observed by the Solar Orbiter/EUI
- Author
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N. Alipour, H. Safari, C. Verbeeck, D. Berghmans, F. Auchère, L. P. Chitta, P. Antolin, K. Barczynski, É. Buchlin, R. Aznar Cuadrado, L. Dolla, M. K. Georgoulis, S. Gissot, L. Harra, A. C. Katsiyannis, D. M. Long, S. Mandal, S. Parenti, O. Podladchikova, E. Petrova, É. Soubrié, U. Schühle, C. Schwanitz, L. Teriaca, M. J. West, and A. N. Zhukov
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,FOS: Physical sciences ,Astronomy and Astrophysics ,F500 ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
Context. Accurate detections of frequent small-scale extreme ultraviolet (EUV) brightenings are essential to the investigation of the physical processes heating the corona. Aims. We detected small-scale brightenings, termed campfires, using their morphological and intensity structures as observed in coronal EUV imaging observations for statistical analysis. Methods. We applied a method based on Zernike moments and a support vector machine (SVM) classifier to automatically identify and track campfires observed by Solar Orbiter/Extreme Ultraviolet Imager (EUI) and Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA). Results. This method detected 8678 campfires (with length scales between 400 km and 4000 km) from a sequence of 50 High Resolution EUV telescope (HRIEUV) 174 Å images. From 21 near co-temporal AIA images covering the same field of view as EUI, we found 1131 campfires, 58% of which were also detected in HRIEUV images. In contrast, about 16% of campfires recognized in HRIEUV were detected by AIA. We obtain a campfire birthrate of 2 × 10−16 m−2 s−1. About 40% of campfires show a duration longer than 5 s, having been observed in at least two HRIEUV images. We find that 27% of campfires were found in coronal bright points and the remaining 73% have occurred out of coronal bright points. We detected 23 EUI campfires with a duration greater than 245 s. We found that about 80% of campfires are formed at supergranular boundaries, and the features with the highest total intensities are generated at network junctions and intense H I Lyman-α emission regions observed by EUI/HRILya. The probability distribution functions for the total intensity, peak intensity, and projected area of campfires follow a power law behavior with absolute indices between 2 and 3. This self-similar behavior is a possible signature of self-organization, or even self-organized criticality, in the campfire formation process.
- Published
- 2022
14. Recovering the origins of the lenticular galaxy NGC 3115 using multiband imaging
- Author
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Duncan A. Forbes, J. A. Hernandez-Jimenez, Arianna Cortesi, Claudia Mendes de Oliveira, L. Santana-Silva, Aaron J. Romanowsky, Leandro Beraldo e Silva, Jean P. Brodie, Fabricio Ferrari, Steven P. Bamford, Marco Grossi, Geferson Lucatelli, Victor P. Debattista, Marina Vika, M. L. Buzzo, Roderik Overzier, A. Werle, Lodovico Coccato, and Carlos Eduardo Barbosa
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Physics ,Active galactic nucleus ,010308 nuclear & particles physics ,Star formation ,FOS: Physical sciences ,Astronomy and Astrophysics ,F500 ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Structural decomposition ,Astrophysics - Astrophysics of Galaxies ,01 natural sciences ,Galaxy ,Luminosity ,Space and Planetary Science ,Bulge ,Astrophysics of Galaxies (astro-ph.GA) ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Spectral energy distribution ,010303 astronomy & astrophysics ,Lenticular galaxy ,Astrophysics::Galaxy Astrophysics - Abstract
A detailed study of the morphology of lenticular galaxies is an important way to understand how this type of galaxy formed and evolves over time. Decomposing a galaxy into its components (disc, bulge, bar, ...) allows recovering the colour gradients present in each system, its star formation history, and its assembly history. We use GALFITM to perform a multi-wavelength structural decomposition of the closest lenticular galaxy, NGC 3115, resulting in the description of its stellar light into several main components: a bulge, a thin disc, a thick disc and also evidence of a bar. We report the finding of central bluer stellar populations in the bulge, as compared to the colour of the galaxy outskirts, indicating either the presence of an Active Galactic Nucleus (AGN) and/or recent star formation activity. From the spectral energy distribution results, we show that the galaxy has a low luminosity AGN component, but even excluding the effect of the nuclear activity, the bulge is still bluer than the outer-regions of the galaxy, revealing a recent episode of star formation. Based on all of the derived properties, we propose a scenario for the formation of NGC 3115 consisting of an initial gas-rich merger, followed by accretions and feedback that quench the galaxy, until a recent encounter with the companion KK084 that reignited the star formation in the bulge, provoked a core displacement in NGC 3115 and generated spiral-like features. This result is consistent with the two-phase formation scenario, proposed in previous studies of this galaxy., Comment: Accepted for publication in MNRAS: 22 pages, 15 figures, 7 tables, 1 appendix
- Published
- 2021
15. sMILES: a library of semi-empirical MILES stellar spectra with variable [α/Fe] abundances
- Author
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A. Vazdekis, Adam T Knowles, C. Allende Prieto, and Anne E. Sansom
- Subjects
Physics ,Stellar population ,010308 nuclear & particles physics ,Milky Way ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,F500 ,Astrophysics ,Astrophysics - Astrophysics of Galaxies ,01 natural sciences ,Astronomical spectroscopy ,Spectral line ,Wavelength ,Stars ,Variable (computer science) ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Abundance (ecology) ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
We present a new library of semi-empirical stellar spectra that is based on the empirical MILES library. A new, high resolution library of theoretical stellar spectra is generated that is specifically designed for use in stellar population studies. We test these models across their full wavelength range against other model libraries and find reasonable agreement in their predictions of spectral changes due to atmospheric $\alpha$-element variations, known as differential corrections. We also test the models against the MILES and MaStar libraries of empirical stellar spectra and also find reasonable agreements, as expected from previous work. We then use the abundance pattern predictions of the new theoretical stellar spectra to differentially correct MILES spectra to create semi-empirical MILES (sMILES) star spectra with abundance patterns that differ from those present in the Milky Way. The final result is 5 families of 801 sMILES stars with [$\alpha$/Fe] abundances ranging from $-$0.20 to 0.60 dex at MILES resolution (FWHM=$2.5\,${\AA}) and wavelength coverage ($3540.5-7409.6\,${\AA}). We make the sMILES library publicly available., Comment: 26 pages, 18 figures plus Supplementary Material. Accepted for publication in MNRAS. Corrected a minor font size error and two figure caption placements from the previous version
- Published
- 2021
16. Additions to the Spectrum of Fe IX in the 110-200 {\AA} Region
- Author
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Alexander N. Ryabtsev, Edward Y. Kononov, and Peter R. Young
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,F300 ,Space and Planetary Science ,Astronomy and Astrophysics ,F500 - Abstract
The spectrum of eight-times ionized iron, Fe IX, was studied in the 110-200 {\AA} region. A low inductance vacuum spark and a 3-m grazing incidence spectrograph were used for the excitation and recording of the spectrum. Previous analyses of Fe IX have been greatly extended and partly revised. The numbers of known lines in the 3p^53d - 3p^54f and 3p^53d - 3p^43d^2 transition arrays are extended to 25 and 81, respectively. Most of the identifications of the Fe IX lines from the 3p^53d - 3p^43d^2 transition array in the solar spectrum have been confirmed and several new identifications are suggested., Comment: Accepted by ApJ, 24 pages, 7 figures, 5 tables
- Published
- 2022
17. Revolutionizing Our Understanding of Particle Energization in Space Plasmas Using On-Board Wave-Particle Correlator Instrumentation
- Author
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Gregory G. Howes, Jaye L. Verniero, Davin E. Larson, Stuart D. Bale, Justin C. Kasper, Keith Goetz, Kristopher G. Klein, Phyllis L. Whittlesey, Roberto Livi, Ali Rahmati, Christopher H. K. Chen, Lynn B. Wilson, Benjamin L. Alterman, and Robert T. Wicks
- Subjects
F300 ,Astronomy and Astrophysics ,F500 - Abstract
A leap forward in our understanding of particle energization in plasmas throughout the heliosphere is essential to answer longstanding questions in heliophysics, including the heating of the solar corona, acceleration of the solar wind, and energization of particles that lead to observable phenomena, such as the Earth’s aurora. The low densities and high temperatures of typical heliospheric environments lead to weakly collisional plasma conditions. Under these conditions, the energization of particles occurs primarily through collisionless interactions between the electromagnetic fields and the individual plasma particles with energies characteristic of a particular interaction. To understand how the plasma heating and particle acceleration impacts the macroscopic evolution of the heliosphere, impacting phenomena such as extreme space weather, it is critical to understand these collisionless wave-particle interactions on the characteristic ion and electron kinetic timescales. Such understanding requires high-cadence measurements of both the electromagnetic fields and the three-dimensional particle velocity distributions. Although existing instrument technology enables these measurements, a major challenge to maximize the scientific return from these measurements is the limited amount of data that can be transmitted to the ground due to telemetry constraints. A valuable, but underutilized, approach to overcome this limitation is to compute on-board correlations of the maximum-cadence field and particle measurements to improve the sampling time by several orders of magnitude. Here we review the fundamentals of the innovative field-particle correlation technique, present a formulation of the technique that can be implemented as an on-board wave-particle correlator, and estimate results that can be achieved with existing instrumental capabilities for particle velocity distribution measurements.
- Published
- 2022
18. First high resolution interferometric observation of a solar prominence with ALMA
- Author
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Nicolas Labrosse, Andrew S Rodger, Krzysztof Radziszewski, Paweł Rudawy, Patrick Antolin, Lyndsay Fletcher, Peter J Levens, Aaron W Peat, Brigitte Schmieder, and Paulo J A Simões
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,F300 ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astrophysics::Solar and Stellar Astrophysics ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,F500 ,Astrophysics::Galaxy Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
We present the first observation of a solar prominence at $84-116$ GHz using the high resolution interferometric imaging of ALMA. Simultaneous observations in H$\alpha$ from Bia{\l}kaw Observatory and with SDO/AIA reveal similar prominence morphology to the ALMA observation. The contribution functions of 3 mm and H$\alpha$ emission are shown to have significant overlap across a range of gas pressures. We estimate the maximum millimetre-continuum optical thickness to be $\tau_\mathrm{3mm}\approx 2$, and the brightness temperature from the observed H$\alpha$ intensity. The brightness temperature measured by ALMA is $\sim 6000-7000$ K in the prominence spine, which correlates well with the estimated brightness temperature for a gas temperature of 8000 K., Comment: 5 pages, 7 figures
- Published
- 2022
19. Evidence of Alfvénic Activity in Jupiter's Mid‐To‐High Latitude Magnetosphere
- Author
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C. T. S. Lorch, L. C. Ray, R. J. Wilson, F. Bagenal, F. Crary, P. A. Delamere, P. A. Damiano, C. E. J. Watt, and F. Allegrini
- Subjects
Geophysics ,Space and Planetary Science ,F500 - Abstract
Using a combination of Juno magnetometer and plasma data, we show evidence of Alfvénic turbulence within the mid‐to‐high latitude magnetosphere with sufficient conditions to trigger auroral particle acceleration. We analyze 12 events that, in agreement with theoretical results, are found to be dissipative at the electron inertial scale. Furthermore, these events contain significant Poynting flux in the range ∼0.8–20 mW/m2 at ionospheric altitudes. This is sufficient to generate auroral emissions. We confirm that such events are incompressible, confirming their Alfvénicity, occur at dissipative scales, have intermittent features present and are multifractal in nature. These results illustrate the importance of turbulence in the mid‐to‐high latitudes of Jupiter's magnetosphere as a driver of particle acceleration.
- Published
- 2022
20. Radial Evolution of Thermal and Suprathermal Electron Populations in the Slow Solar Wind from 0.13 to 0.5 au: Parker Solar Probe Observations
- Author
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Joel B. Abraham, Christopher J. Owen, Daniel Verscharen, Mayur Bakrania, David Stansby, Robert T. Wicks, Georgios Nicolaou, Phyllis L. Whittlesey, Jeffersson A. Agudelo Rueda, Seong-Yeop Jeong, and Laura Berčič
- Subjects
Earth and Planetary Astrophysics (astro-ph.EP) ,F300 ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,F500 ,Space Physics (physics.space-ph) ,Physics - Plasma Physics ,Plasma Physics (physics.plasm-ph) ,Astrophysics - Solar and Stellar Astrophysics ,Physics - Space Physics ,Space and Planetary Science ,Physics::Space Physics ,Astrophysics::Earth and Planetary Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We develop and apply a bespoke fitting routine to a large volume of solar wind electron distribution data measured by Parker Solar Probe (PSP) over its first five orbits, covering radial distances from 0.13 to 0.5 au. We characterise the radial evolution of the electron core, halo and strahl populations in the slow solar wind during these orbits. The fractional densities of these three electron populations provide evidence for the growth of the combined suprathermal halo and strahl populations from 0.13 to 0.17 au. Moreover, the growth in the halo population is not matched by a decrease of the strahl population at these distances, as has been reported for previous observations at distances greater than 0.3 au. We also find that the halo is negligible at small heliocentric distances. The fractional strahl density remains relatively constant ~1 % below 0.2 au, suggesting that the rise in the relative halo density is not solely due to the transfer of strahl electrons into the halo., Published in ApJ
- Published
- 2022
21. Decoding NGC 628 with radiative transfer methods
- Author
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Rushton, Mark, Popescu, Cristina, Inman, Christopher James, Natale, Giovanni, and Pricopi, D
- Subjects
Space and Planetary Science ,F520 ,Astrophysics of Galaxies (astro-ph.GA) ,F510 ,F521 ,FOS: Physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astronomy and Astrophysics ,F500 ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Astrophysics::Galaxy Astrophysics - Abstract
We present an axi-symmetric model for the ultraviolet (UV)-to-submillimetre (submm) images of the nearly face-on spiral galaxy NGC 628. It was calculated using a radiative transfer (RT) code, accounting for the absorption and re-emission of starlight by dust in the interstellar medium of this galaxy. The code incorporates emission from Polycyclic Aromatic Hydrocarbons, anisotropic scattering and stochastic heating of the grains. This is the second successful modelling of a face-on spiral galaxy with RT methods, whereby the large-scale geometry of stars and dust is self-consistently determined. The solution was obtained by fitting azimuthally averaged profiles in the UV, optical and submm. The model predicts remarkably well all characteristics of the profiles, including the increase by a factor of 1.8 of the scale-length of the infrared emissivity between 70 and 500 $μ$m. We find that NGC 628 did not undergo an efficient inside-out disk growth, as predicted by semi-analytical hierarchical models for galaxy formation. We also find large amounts of dust grains at large radii, that could involve efficient transport mechanisms from the inner disk. Our results show that 71% of the dust emission in NGC 628 is powered by the young stellar populations, with the old stellar populations from the bulge contributing 65% to the heating of the dust in the central region ($R, 27 pages, 18 figures. Accepted for publication in MNRAS
- Published
- 2022
22. Bending waves excited by irregular gas inflow along warps
- Author
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Leandro Beraldo e Silva, Kathryne Jeannine Daniel, Victor Debattista, and Tigran Khachaturyants
- Subjects
Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,F500 ,Astrophysics - Astrophysics of Galaxies ,Astrophysics::Galaxy Astrophysics - Abstract
Gaia has revealed clear evidence of bending waves in the vertical kinematics of stars in the Solar Neighbourhood. We study bending waves in two simulations, one warped, with the warp due to misaligned gas inflow, and the other unwarped. We find slow, retrograde bending waves in both models, with the ones in the warped model having larger amplitudes. We also find fast, prograde bending waves. Prograde bending waves in the unwarped model are very weak, in agreement with the expectation that these waves should decay on short, ~ crossing, timescales, due to strong winding. However, prograde bending waves are much stronger for the duration of the warped model, pointing to irregular gas inflow along the warp as a continuous source of excitation. We demonstrate that large amplitude bending waves that propagate through the Solar Neighbourhood give rise to a correlation between the mean vertical velocity and the angular momentum, with a slope consistent with that found by Gaia. The bending waves affect populations of all ages, but the sharpest features are found in the young populations, hinting that short wavelength waves are not supported by the older, kinematically hotter, populations. Our results demonstrate the importance of misaligned gas accretion as a recurrent source of vertical perturbations of disc galaxies, including in the Milky Way., Comment: 21 pages, 20 figures; Published on MNRAS
- Published
- 2022
23. Revealing dual radio sources in a sub-kpc-scale binary active galactic nucleus candidate
- Author
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J E Brooks, M K Argo, Hojin Cho, Jong-Hak Woo, Taehyun Jung, and N Wrigley
- Subjects
Space and Planetary Science ,Astronomy and Astrophysics ,F500 - Abstract
We present new imaging of a sub-kpc-scale binary active galactic nucleus (AGN) candidate from the Karl G. Jansky Very Large Array (VLA) and the Multi-Element Radio Linked Interferometer Network (e-MERLIN). Two unresolved radio sources of similar luminosity around 1022 WHz−1 are identified in ∼35 h of e-MERLIN 6 cm imaging. These radio sources have an angular separation of 0.19 ± 0.06 arcsec and position angle (PA) of 22° ± 10°, corresponding to a projected separation of 0.95 ± 0.29 kpc at the epoch of the source. Our results suggest the presence of a kpc-scale active black hole pair hosted by two galaxies in the late stage of a merger at z = 0.35. This work follows Woo et al., which presented two optical sources with a similar separation and PA, and a velocity separation of 200 km s−1. Our target adds to the currently limited sample of close-separation binary AGNs, which will aid in understanding the frequency of mergers and the stochastic gravitational wave background.
- Published
- 2022
24. Statistical Comparison of Electron Loss and Enhancement in the Outer Radiation Belt During Storms
- Author
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S. D. Walton, C. Forsyth, I. J. Rae, N. P. Meredith, J. K. Sandhu, M.‐T. Walach, and K. R. Murphy
- Subjects
Geophysics ,F300 ,Space and Planetary Science ,Physics::Space Physics ,F500 - Abstract
The near-relativistic electron population in the outer Van Allen radiation belt is highly dynamic and strongly coupled to geomagnetic activity such as storms and substorms, which are driven by the interaction of the magnetosphere with the solar wind. The energy, content and spatial extent of electrons in the outer radiation belt can vary on timescales of hours to days, dictated by the continuously evolving influence of acceleration and loss processes. While net changes in the electron population are directly observable, the relative influence of different processes is far from fully understood. Using a continuous 12-year dataset from the Proton Electron Telescope (PET) on board the Solar Anomalous Magnetospheric Particle Explorer (SAMPEX), we statistically compare the relative variations of trapped electrons to those in the bounce loss cone. Our results show that there is a proportional increase in flux entering the bounce loss cone outside the plasmapause during storm main phase and early recovery phase. Loss enhancement is sustained on the dawnside throughout the recovery phase while loss on the duskside is enhanced around minimum Sym-H and quickly diminishes. Spatial variations are also examined in relation to geomagnetic activity, making comparisons to possible causal wave modes such as whistler-mode chorus and plasmaspheric hiss.
- Published
- 2022
25. The secular growth of bars revealed by flat (peak + shoulders) density profiles
- Author
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Stuart Robert Anderson, Victor P Debattista, Peter Erwin, David J Liddicott, Nathan Deg, and Leandro Beraldo e Silva
- Subjects
musculoskeletal diseases ,genetic structures ,High Energy Physics::Phenomenology ,FOS: Physical sciences ,Astronomy and Astrophysics ,Computer Science::Human-Computer Interaction ,F500 ,Astrophysics - Astrophysics of Galaxies ,Condensed Matter::Soft Condensed Matter ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Nuclear Experiment ,human activities ,Computer Science::Cryptography and Security - Abstract
The major-axis density profiles of bars are known to be either exponential or 'flat'. We develop an automated non-parametric algorithm to detect flat profiles and apply it to a suite of simulations (with and without gas). We demonstrate that flat profiles are a manifestation of a bar's secular growth, producing a 'shoulder' region (an overdensity above an exponential) in its outskirts. Shoulders are not present when bars form, but develop as the bar grows. If the bar does not grow, shoulders do not form. Shoulders are often accompanied by box/peanut bulges, but develop separately from them and are independent tracers of a bar's growth. They can be observed at a wide range of viewing orientations with only their slope varying significantly with inclination. We present evidence that shoulders are produced by looped x1 orbits. Since the growth rate of the bar moderately correlates with the growth rate of the shoulder strength, these orbits are probably recently trapped. Shoulders therefore are evidence of bar growth. The properties of the shoulders do not, however, establish the age of a bar, because secondary buckling or strong spirals may destroy shoulders, and also because shoulders do not form if the bar does not grow much. In particular, our results show that an exponential profile is not necessarily an indication of a young bar., Comment: 20 pages, 23 figures, 2 tables. Published in MNRAS
- Published
- 2022
26. Correlated orientations of the axes of large quasar groups on Gpc scales
- Author
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Tracey Friday, Roger G Clowes, and Gerard M Williger
- Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Space and Planetary Science ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,F500 ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
Correlated orientations of quasar optical and radio polarisation, and of radio jets, have been reported on Gpc scales, possibly arising from intrinsic alignment of spin axes. Optical quasar polarisation appears to be preferentially either aligned or orthogonal to the host large-scale structure, specifically large quasar groups (LQGs). Using a sample of 71 LQGs at redshifts $1.0 \leq z \leq 1.8$, we investigate whether LQGs themselves exhibit correlated orientation. We find that LQG position angles (PAs) are unlikely to be drawn from a uniform distribution ($p$-values $0.008 \lesssim p \lesssim 0.07$). The LQG PA distribution is bimodal, with median modes at $\bar{\theta}\sim45\pm2^{\circ}, 136\pm2^{\circ}$, remarkably close to the mean angles of quasar radio polarisation reported in two regions coincident with our LQG sample. We quantify the degree of alignment in the PA data, and find that LQGs are aligned and orthogonal across very large scales. The maximum significance is $\simeq 0.8\%$ ($2.4\sigma$) at typical angular (proper) separations of $\sim 30^{\circ}$ (1.6 Gpc). If the LQG orientation correlation is real, it represents large-scale structure alignment over scales larger than those predicted by cosmological simulations and at least an order of magnitude larger than any so far observed, with the exception of quasar-polarisation / radio-jet alignment. We conclude that LQG alignment helps explain quasar-polarisation / radio-jet alignment, but raises challenging questions about the origin of the LQG correlation and the assumptions of the concordance cosmological model., Comment: Accepted for MNRAS
- Published
- 2022
27. LeMMINGs - II. The e-MERLIN legacy survey of nearby galaxies. The deepest radio view of the Palomar sample on parsec scale
- Author
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David A. Green, Elmar Körding, Susanne Aalto, David R. Williams, Bililign T. Dullo, Alison B. Peck, Ranieri D. Baldi, C. Romero-Cañizales, Willem A. Baan, I. M. McHardy, Megan Argo, Eskil Varenius, Antxon Alberdi, Miguel A. Pérez-Torres, Payaswini Saikia, Francesca Panessa, Stephane Corbel, John S. Gallagher, Martin Ward, R. C. Kennicutt, George J. Bendo, Jeremy Yates, Francesco Shankar, P. Uttley, Hans-Rainer Klöckner, Ralph Spencer, T. J. Maccarone, Johan H. Knapen, Ian R. Stevens, Danielle Fenech, T. W. B. Muxlow, C. G. Mundell, Robert Beswick, Elias Brinks, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Unité Scientifique de la Station de Nançay (USN), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Ministerio de Ciencia, Innovación y Universidades (España), Comunidad de Madrid, Universidad Complutense de Madrid, University of Bath, University of Wisconsin-Madison, European Commission, Green, David [0000-0003-3189-9998], Apollo - University of Cambridge Repository, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)
- Subjects
Astrofísica ,active [Galaxies] ,galaxies: jet ,media_common.quotation_subject ,Astronomy ,galaxies: active ,FOS: Physical sciences ,Scale (descriptive set theory) ,Astrophysics ,F500 ,galaxies [Radio continuum] ,01 natural sciences ,jet [Galaxies] ,star formation [Galaxies] ,Spectral line ,Parsec ,0103 physical sciences ,010303 astronomy & astrophysics ,MERLIN ,media_common ,Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,radio continuum: galaxies ,010308 nuclear & particles physics ,Astronomy and Astrophysics ,Sample (graphics) ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,Universe ,Astronomía ,Space and Planetary Science ,nuclei [Galaxies] ,Astrophysics of Galaxies (astro-ph.GA) ,galaxies: star formation ,galaxies: nuclei ,Astrophysics - High Energy Astrophysical Phenomena ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,Data release - Abstract
Full list of authors: Baldi, R. D.; Williams, D. R. A.; McHardy, I. M.; Beswick, R. J.; Brinks, E.; Dullo, B. T.; Knapen, J. H.; Argo, M. K.; Aalto, S.; Alberdi, A.; Baan, W. A.; Bendo, G. J.; Corbel, S.; Fenech, D. M.; Gallagher, J. S.; Green, D. A.; Kennicutt, R. C.; Klöckner, H. -R.; Körding, E.; Maccarone, T. J.; Muxlow, T. W. B.; Mundell, C. G.; Panessa, F.; Peck, A. B.; Pérez-Torres, M. A.; Romero-Cañizales, C.; Saikia, P.; Shankar, F.; Spencer, R. E.; Stevens, I. R.; Varenius, E.; Ward, M. J.; Yates, J.; Uttley, P., We present the second data release of high-resolution (≤0.2 arcsec) 1.5-GHz radio images of 177 nearby galaxies from the Palomar sample, observed with the e-MERLIN array, as part of the Legacy e-MERLIN Multi-band Imaging of Nearby Galaxies Sample (LeMMINGs) survey. Together with the 103 targets of the first LeMMINGs data release, this represents a complete sample of 280 local active (LINER and Seyfert) and inactive galaxies (H ii galaxies and absorption line galaxies, ALG). This large program is the deepest radio survey of the local Universe, ≳1017.6 W Hz-1, regardless of the host and nuclear type: we detect radio emission ≳0.25 mJy beam-1 for 125/280 galaxies (44.6 per cent) with sizes of typically ≲100 pc. Of those 125, 106 targets show a core which coincides within 1.2 arcsec with the optical nucleus. Although we observed mostly cores, around one third of the detected galaxies features jetted morphologies. The detected radio core luminosities of the sample range between ∼1034 and 1040 erg s-1. LINERs and Seyferts are the most luminous sources, whereas H ii galaxies are the least. LINERs show FR I-like core-brightened radio structures while Seyferts reveal the highest fraction of symmetric morphologies. The majority of H ii galaxies have single radio core or complex extended structures, which probably conceal a nuclear starburst and/or a weak active nucleus (seven of them show clear jets). ALGs, which are typically found in evolved ellipticals, although the least numerous, exhibit on average the most luminous radio structures, similar to LINERs. © 2020 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society., The authors thank the anonymous referee for his/her helpful comments to improve the manuscript. AA and MAPT acknowledge support from the Spanish MCIU through grant PGC2018-098915-B-C21 and from the State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severo Ochoa' award for the Instituto de Astrof ' isica de Andalucia (SEV-2017-0709). BTD acknowledges support from a Spanish postdoctoral fellowship 'Ayudas 1265 para la atraccion del talento investigador. Modalidad 2: jovenes investigadores.' funded by Comunidad de Madrid under grant number 2016-T2/TIC-2039. BTD also acknowledges support from grant 'Ayudas para la realizaci on de proyectos de I + D para jovenes doctores 2019.' funded by Comunidad de Madrid and Universidad Complutense de Madrid under grant number PR65/19-22417. JHK acknowledges financial support from the European Union's Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement No. 721463 to the SUNDIAL ITN network, from the State Research Agency (AEI-MCINN) of the Spanish Ministry of Science and Innovation under the grant 'The structure and evolution of galaxies and their central regions' with reference PID2019-105602GB-I00/10.13039/501100011033, and from IAC project P/300724, financed by the Ministry of Science and Innovation, through the State Budget and by the Canary Islands Department of Economy, Knowledge and Employment, through the Regional Budget of the Autonomous Community. JSG thanks the University of Wisconsin-Madison and its Foundation for support of this research through his Rupple Bascom Professorship. FS acknowledges partial support from a Leverhulme Trust Research fellowship. CGM acknowledges support from the University of Bath and Jim and Hiroko Sherwin. e-MERLIN is a National Facility operated by the University of Manchester at Jodrell Bank Observatory on behalf of STFC, part of UK Research and Innovation.
- Published
- 2021
28. Multi-Scale Variability of Coronal Loops Set by Thermal Non-Equilibrium and Instability as a Probe for Coronal Heating
- Author
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Patrick Antolin and Clara Froment
- Subjects
F300 ,Physics::Space Physics ,Astrophysics::Solar and Stellar Astrophysics ,Astronomy and Astrophysics ,F500 - Abstract
Solar coronal loops are the building blocks of the solar corona. These dynamic structures are shaped by the magnetic field that expands into the solar atmosphere. They can be observed in X-ray and extreme ultraviolet (EUV), revealing the high plasma temperature of the corona. However, the dissipation of magnetic energy to heat the plasma to millions of degrees and, more generally, the mechanisms setting the mass and energy circulation in the solar atmosphere are still a matter of debate. Furthermore, multi-dimensional modelling indicates that the very concept of a coronal loop as an individual entity and its identification in EUV images is ill-defined due to the expected stochasticity of the solar atmosphere with continuous magnetic connectivity changes combined with the optically thin nature of the solar corona. In this context, the recent discovery of ubiquitous long-period EUV pulsations, the observed coronal rain properties and their common link in between represent not only major observational constraints for coronal heating theories but also major theoretical puzzles. The mechanisms of thermal non-equilibrium (TNE) and thermal instability (TI) appear in concert to explain these multi-scale phenomena as evaporation-condensation cycles. Recent numerical efforts clearly illustrate the specific but large parameter space involved in the heating and cooling aspects, and the geometry of the loop affecting the onset and properties of such cycles. In this review we will present and discuss this new approach into inferring coronal heating properties and understanding the mass and energy cycle based on the multi-scale intensity variability and cooling properties set by the TNE-TI scenario. We further discuss the major numerical challenges posed by the existence of TNE cycles and coronal rain, and similar phenomena at much larger scales in the Universe.
- Published
- 2022
29. Tidally Tilted Pulsations in HD 265435, a subdwarf B Star with a Close White Dwarf Companion
- Author
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Rahul Jayaraman, Gerald Handler, Saul A. Rappaport, Jim Fuller, Donald W. Kurtz, Stéphane Charpinet, George R. Ricker, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and ANR-17-CE31-0018,INSIDE,Inversion astérosismique de la stratification en carbone / oxygène des noyaux d'étoiles de faible masse évoluées(2017)
- Subjects
Pulsation modes ,Computer Science::Information Retrieval ,Asteroseismology ,FOS: Physical sciences ,Tidal distortion ,Astronomy and Astrophysics ,F500 ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,[SDU]Sciences of the Universe [physics] ,B subdwarf stars ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics - Abstract
Tidally tilted pulsators (TTPs) are an intriguing new class of oscillating stars in binary systems; in such stars, the pulsation axis coincides with the line of apsides, or semi-major axis, of the binary. All three TTPs discovered so far have been $\delta$~Scuti stars. In this Letter, we report the first conclusive discovery of tidally tilted pulsations in a subdwarf B (sdB) star. HD 265435 is an sdB--white dwarf binary with a 1.65-hr period that has been identified and characterized as the nearest potential Type Ia supernova progenitor. Using TESS 20-s cadence data from Sectors 44 and 45, we show that the pulsation axis of the sdB star has been tidally tilted into the orbital plane and aligned with the tidal axis of the binary. We identify 31 independent pulsation frequencies, 27 of which have between 1 and 7 sidebands separated by the orbital frequency ($\nu_{\rm orb}$), or multiples thereof. Using the observed amplitude and phase variability due to tidal tilting, we assign $\ell$ and $m$ values to most of the observed oscillation modes and use these mode identifications to generate preliminary asteroseismic constraints. Our work significantly expands our understanding of TTPs, as we now know that (i) they can be found in stars other than $\delta$~Scuti pulsators, especially highly-evolved stars that have lost their H-rich envelopes, and (ii) tidally tilted pulsations can be used to probe the interiors of stars in very tight binaries., Comment: 17 pages, 5 figures + 2 appendix figures, 1 table; accepted for publication in ApJL
- Published
- 2022
30. Study of chemically peculiar stars – I. High-resolution spectroscopy and K2 photometry of Am stars in the region of M44
- Author
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Santosh Joshi, Otto Trust, E Semenko, P E Williams, P Lampens, P De Cat, L Vermeylen, D L Holdsworth, R A García, S Mathur, A R G Santos, D Mkrtichian, A Goswami, M Cuntz, A P Yadav, M Sarkar, B C Bhatt, F Kahraman Aliçavuş, M D Nhlapo, M N Lund, P P Goswami, I Savanov, A Jorissen, E Jurua, E Avvakumova, E S Dmitrienko, N K Chakradhari, M K Das, S Chowdhury, O P Abedigamba, I Yakunin, B Letarte, and D Karinkuzhi
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Polarimetric ,Photometric [Techniques] ,Astrophysics::Solar and Stellar Astrophysics ,FOS: Physical sciences ,Astronomy and Astrophysics ,Activity [Stars] ,F500 ,Spectroscopic ,Chemically peculiar [Stars] ,Binaries [Stars] ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
We present a study based on the high-resolution spectroscopy and K2 space photometry of five chemically peculiar stars in the region of the open cluster M44. The analysis of the high-precision photometric K2 data reveals that the light variations in HD 73045 and HD 76310 are rotational in nature and caused by spots or cloud-like co-rotating structures, which are non-stationary and short-lived. The time-resolved radial velocity measurements, in combination with the K2 photometry, confirm that HD 73045 does not show any periodic variability on timescales shorter than 1.3 d, contrary to previous reports in the literature. In addition to these new rotational variables, we discovered a new heartbeat system, HD 73619, where no pulsational signatures are seen. The spectroscopic and spectropolarimetric analyses indicate that HD 73619 belongs to the peculiar Am class, with either a weak or no magnetic field considering the 200 G detection limit of our study. The Least-Squares Deconvolution (LSD) profiles for HD 76310 indicate a complex structure in its spectra suggesting that this star is either part of a binary system or surrounded by a cloud shell. When placed in the Hertzsprung-Russell diagram, all studied stars are evolved from main-sequence and situated in the $\delta$ Scuti instability strip. The present work is relevant for further detailed studies of CP stars, such as inhomogeneities (including spots) in the absence of magnetic fields and the origin of the pulsational variability in heartbeat systems., Comment: Accepted for publication in MNRAS
- Published
- 2022
31. Age dissection of the vertical breathing motions in Gaia DR2: evidence for spiral driving
- Author
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Soumavo Ghosh, Victor Debattista, and Tigran Khachaturyants
- Subjects
Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,digestive, oral, and skin physiology ,Physics::Medical Physics ,FOS: Physical sciences ,Astronomy and Astrophysics ,F500 ,Astrophysics - Astrophysics of Galaxies ,Astrophysics::Galaxy Astrophysics - Abstract
Gaia DR2 has revealed breathing motions in the Milky Way, with stars on both sides of the Galactic mid-plane moving coherently towards or away from it. The generating mechanism of these breathing motions is thought to be spiral density waves. Here we test this hypothesis. Using a self-consistent, high-resolution simulation with star formation, and which hosts prominent spirals, we first study the signatures of breathing motions excited by spirals. In the model, the breathing motions induced by the spiral structure have an increasing amplitude with distance from the mid-plane, pointing to an internal cause for them. We then show that, at fixed height, the breathing motion amplitude decreases with age. Next, we investigate the signature of the breathing motions in the Gaia DR2 dataset. We demonstrate that, at the location with a consistently large breathing motion, the corresponding amplitude increases monotonically with distance from the mid-plane, in agreement with the model. Furthermore, we show that at the same location, the breathing motion amplitude decreases with age, again similar to what we find in the model. This strengthens the case that the observed breathing motions are driven by spiral density waves., 17 pages, 19 figures, accepted for publication in MNRAS
- Published
- 2022
32. B-fields in Star-forming Region Observations (BISTRO): Magnetic Fields in the Filamentary Structures of Serpens Main
- Author
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Woojin Kwon, Kate Pattle, Sarah Sadavoy, Charles L. H. Hull, Doug Johnstone, Derek Ward-Thompson, James Di Francesco, Patrick M. Koch, Ray Furuya, Yasuo Doi, Valentin J. M. Le Gouellec, Jihye Hwang, A-Ran Lyo, Archana Soam, Xindi Tang, Thiem Hoang, Florian Kirchschlager, Chakali Eswaraiah, Lapo Fanciullo, Kyoung Hee Kim, Takashi Onaka, Vera Könyves, Ji-hyun Kang, Chang Won Lee, Motohide Tamura, Pierre Bastien, Tetsuo Hasegawa, Shih-Ping Lai, Keping Qiu, David Berry, Doris Arzoumanian, Tyler L. Bourke, Do-Young Byun, Wen Ping Chen, Huei-Ru Vivien Chen, Mike Chen, Zhiwei Chen, Tao-Chung Ching, Jungyeon Cho, Yunhee Choi, Minho Choi, Antonio Chrysostomou, Eun Jung Chung, Simon Coudé, Sophia Dai, Pham Ngoc Diep, Yan Duan, Hao-Yuan Duan, David Eden, Jason Fiege, Laura M. Fissel, Erica Franzmann, Per Friberg, Rachel Friesen, Gary Fuller, Tim Gledhill, Sarah Graves, Jane Greaves, Matt Griffin, Qilao Gu, Ilseung Han, Jennifer Hatchell, Saeko Hayashi, Martin Houde, Tsuyoshi Inoue, Shu-ichiro Inutsuka, Kazunari Iwasaki, Il-Gyo Jeong, Miju Kang, Janik Karoly, Akimasa Kataoka, Koji Kawabata, Francisca Kemper, Kee-Tae Kim, Gwanjeong Kim, Mi-Ryang Kim, Shinyoung Kim, Jongsoo Kim, Jason Kirk, Masato I. N. Kobayashi, Takayoshi Kusune, Jungmi Kwon, Kevin Lacaille, Chi-Yan Law, Chin-Fei Lee, Yong-Hee Lee, Hyeseung Lee, Jeong-Eun Lee, Sang-Sung Lee, Dalei Li, Di Li, Hua-bai Li, Sheng-Jun Lin, Sheng-Yuan Liu, Hong-Li Liu, Junhao Liu, Tie Liu, Xing Lu, Steve Mairs, Masafumi Matsumura, Brenda Matthews, Gerald Moriarty-Schieven, Tetsuya Nagata, Fumitaka Nakamura, Hiroyuki Nakanishi, Nguyen Bich Ngoc, Nagayoshi Ohashi, Geumsook Park, Harriet Parsons, Nicolas Peretto, Felix Priestley, Tae-Soo Pyo, Lei Qian, Ramprasad Rao, Jonathan Rawlings, Mark G. Rawlings, Brendan Retter, John Richer, Andrew Rigby, Hiro Saito, Giorgio Savini, Masumichi Seta, Yoshito Shimajiri, Hiroko Shinnaga, Mehrnoosh Tahani, Ya-Wen Tang, Kohji Tomisaka, Le Ngoc Tram, Yusuke Tsukamoto, Serena Viti, Hongchi Wang, Jia-Wei Wang, Anthony Whitworth, Jintai Wu, Jinjin Xie, Hsi-Wei Yen, Hyunju Yoo, Jinghua Yuan, Hyeong-Sik Yun, Tetsuya Zenko, Yapeng Zhang, Chuan-Peng Zhang, Guoyin Zhang, Jianjun Zhou, Lei Zhu, Ilse de Looze, Philippe André, C. Darren Dowell, Stewart Eyres, Sam Falle, Jean-François Robitaille, Sven van Loo, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France
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POLARIZATION ,FOS: Physical sciences ,F500 ,IMAGING POLARIMETRY ,1ST ,INTERSTELLAR CLOUDS ,Astrophysics::Solar and Stellar Astrophysics ,SCUBA-2 ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] ,LEGACY ,Astronomy and Astrophysics ,VELOCITY ,Astrophysics - Astrophysics of Galaxies ,SPITZER ,Astrophysics - Solar and Stellar Astrophysics ,Physics and Astronomy ,Space and Planetary Science ,[SDU]Sciences of the Universe [physics] ,OUTFLOWS ,Astrophysics of Galaxies (astro-ph.GA) ,STRENGTHS - Abstract
We present 850 $��$m polarimetric observations toward the Serpens Main molecular cloud obtained using the POL-2 polarimeter on the James Clerk Maxwell Telescope (JCMT) as part of the B-fields In STar-forming Region Observations (BISTRO) survey. These observations probe the magnetic field morphology of the Serpens Main molecular cloud on about 6000 au scales, which consists of cores and six filaments with different physical properties such as density and star formation activity. Using the histogram of relative orientation (HRO) technique, we find that magnetic fields are parallel to filaments in less dense filamentary structures where $N_{H_2} < 0.93\times 10^{22}$ cm$^{-2}$ (magnetic fields perpendicular to density gradients), while being perpendicular to filaments (magnetic fields parallel to density gradients) in dense filamentary structures with star formation activity. Moreover, applying the HRO technique to denser core regions, we find that magnetic field orientations change to become perpendicular to density gradients again at $N_{H_2} \approx 4.6 \times 10^{22}$ cm$^{-2}$. This can be interpreted as a signature of core formation. At $N_{H_2} \approx 16 \times 10^{22}$ cm$^{-2}$ magnetic fields change back to being parallel to density gradients once again, which can be understood to be due to magnetic fields being dragged in by infalling material. In addition, we estimate the magnetic field strengths of the filaments ($B_{POS} = 60-300~��$G)) using the Davis-Chandrasekhar-Fermi method and discuss whether the filaments are gravitationally unstable based on magnetic field and turbulence energy densities., 18 pages, accepted for publication in ApJ
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- 2022
33. Strong CO Absorption Features in Massive ETGs
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Francesco La Barbera, Adam Knowles, Carlos Allende Prieto, Alexandre Vazdekis, and Elham Eftekhari
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Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,FOS: Physical sciences ,Astronomy and Astrophysics ,F500 ,Astrophysics - Astrophysics of Galaxies - Abstract
Massive Early-Type Galaxies (ETG) in the local Universe are believed to be the most mature stage of galaxy evolution. Their stellar population content reveals the evolutionary history of these galaxies. However, while state-of-the-art Stellar Population Synthesis (SPS) models provide an accurate description of observed galaxy spectra in the optical range, the modelling in the Near-Infrared (NIR) is still in its infancy. Here we focus on NIR CO absorption features to show, in a systematic and comprehensive manner, that for massive ETGs, all CO indices, from H through to K band, are significantly stronger than currently predicted by SPS models. We explore and discuss several possible explanations of this "CO mismatch", including the effect of intermediate-age, AGB-dominated, stellar populations, high metallicity populations, non-solar abundance ratios and the initial mass function. While none of these effects is able to reconcile models and observations, we show that ad-hoc "empirical" corrections, taking into account the effect of CO-strong giant stars in the low-temperature regime, provide model predictions that are closer to the observations. Our analysis points to the effect of carbon abundance as the most likely explanation of NIR CO line-strengths, indicating possible routes for improving the SPS models in the NIR., 24 pages, 12 figures, accepted for publication in MNRAS
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- 2022
34. Revised Analysis of Fe vii
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Peter Young, Alexander Kramida, and Sasha Ryabtsev
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Space and Planetary Science ,F300 ,Astronomy and Astrophysics ,F500 - Abstract
New spectrograms of multiply ionized iron have been recorded and analyzed, targeting the Fe vii spectrum. As a result, several previously unknown spectral lines and energy levels have been identified in this spectrum. These new data have been analyzed together with all previously published laboratory and astrophysical data on this spectrum. The energy levels have been interpreted using parametric calculations with Cowan codes. Radiative transition rates calculated in this work supplemented other previously published calculations in constructing a complete set of recommended transition probabilities. The ionization energy of Fe vii has been redetermined with a fivefold improvement in accuracy. Its new value is 1,007,928(20) cm−1, corresponding to 124.9671(25) eV.
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- 2022
35. Oscillatory Reconnection of a 2D X-point in a hot coronal plasma
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Gert Botha, Stephane Regnier, James McLaughlin, and Konstantinos Karampelas
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MHD WAVE-PROPAGATION ,QUASI-PERIODIC PULSATIONS ,Science & Technology ,F300 ,FOS: Physical sciences ,Astronomy and Astrophysics ,F500 ,Astronomy & Astrophysics ,NULL POINTS ,SOLAR CORONA ,STELLAR FLARES ,ALFVENIC WAVES ,Physics - Plasma Physics ,Plasma Physics (physics.plasm-ph) ,NEIGHBORHOOD ,LY-ALPHA ,Astrophysics - Solar and Stellar Astrophysics ,MAGNETIC RECONNECTION ,RADIO-BURSTS ,Space and Planetary Science ,Physics::Plasma Physics ,Physical Sciences ,Physics::Space Physics ,Astrophysics::Solar and Stellar Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
Oscillatory reconnection (a relaxation mechanism with periodic changes in connectivity) has been proposed as a potential physical mechanism underpinning several periodic phenomena in the solar atmosphere including, but not limited to, quasi-periodic pulsations (QPPs). Despite its importance, however, the mechanism has never been studied within a hot, coronal plasma. We investigate oscillatory reconnection in a one million Kelvin plasma by solving the fully-compressive, resistive MHD equations for a 2D magnetic X-point under coronal conditions using the PLUTO code. We report on the resulting oscillatory reconnection including its periodicity and decay rate. We observe a more complicated oscillating profile for the current density compared to that found for a cold plasma, due to mode-conversion at the equipartition layer. We also consider, for the first time, the effect of adding anisotropic thermal conduction to the oscillatory reconnection mechanism, and we find this simplifies the spectrum of the oscillation profile and increases the decay rate. Crucially, the addition of thermal conduction does not prevent the oscillatory reconnection mechanism from manifesting. Finally, we reveal a relationship between the equilibrium magnetic field strength, decay rate, and period of oscillatory reconnection, which opens the tantalising possibility of utilizing oscillatory reconnection as a seismological tool., 17 pages, 13 figures, accepted for publication in ApJ
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- 2022
36. Distributions of Birkeland Current Density Observed by AMPERE are Heavy‐Tailed or Long‐Tailed
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John C. Coxon, Gareth Chisham, Mervyn P. Freeman, Brian J. Anderson, and Robert C. Fear
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Geophysics ,F300 ,Space and Planetary Science ,F500 - Abstract
We analyze probability distributions of Birkeland current densities measured by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE). We find that the distributions are leptokurtic rather than normal and they are sometimes heavy-tailed. We fit q-exponential functions to the distributions and use these to estimate where the largest currents are likely to occur. The shape and scale parameters of the fitted q-exponential distribution vary with location: The scale parameter maximises for current densities with the same polarity and in the same location as the average Region 1 current, whereas the shape parameter maximises for current densities with the same polarity and in the same location as the average Region 2 current. We find that current densities |J|≥ 0.2 μA m−2 are most likely to occur in the average Region 1 current region, and second most likely to occur in the average Region 2 current region. However, for extreme currents (|J|≥ 4.0 μA m−2), we find that the most likely location is colocated with the average Region 2 current region on the dayside, at a colatitude of 18° − 22°.
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- 2022
37. The Stability of the Electron Strahl against the Oblique Fast-magnetosonic/Whistler Instability in the Inner Heliosphere
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Seong-Yeop Jeong, Joel B. Abraham, Daniel Verscharen, Laura Berčič, David Stansby, Georgios Nicolaou, Christopher J. Owen, Robert T. Wicks, Andrew N. Fazakerley, Jeffersson A. Agudelo Rueda, and Mayur Bakrania
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Plasma Physics (physics.plasm-ph) ,Astrophysics - Solar and Stellar Astrophysics ,Physics - Space Physics ,F300 ,Space and Planetary Science ,Physics::Space Physics ,FOS: Physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astronomy and Astrophysics ,F500 ,Solar and Stellar Astrophysics (astro-ph.SR) ,Space Physics (physics.space-ph) ,Physics - Plasma Physics - Abstract
We analyze the micro-kinetic stability of the electron strahl in the solar wind depending on heliocentric distance. The oblique fast-magnetosonic/whistler (FM/W) instability has emerged in the literature as a key candidate mechanism for the effective scattering of the electron strahl into the electron halo population. Using data from Parker Solar Probe (PSP) and Helios, we compare the measured strahl properties with the analytical thresholds for the oblique FM/W instability in the low- and high-$\beta_{\parallel c}$ regimes, where $\beta_{\parallel c}$ is the ratio of the core parallel thermal pressure to the magnetic pressure. Our PSP and Helios data show that the electron strahl is on average stable against the oblique FM/W instability in the inner heliosphere. Our analysis suggests that the instability, if at all, can only be excited sporadically and on short timescales. We discuss the caveats of our analysis and potential alternative explanations for the observed scattering of the electron strahl in the solar wind. Furthermore, we recommend the numerical evaluation of the stability of individual distributions in the future to account for any uncertainties in the validity of the analytical expressions for the instability thresholds., Comment: Accepted in ApJL
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- 2022
38. The Variability of the Black Hole Image in M87 at the Dynamical Timescale
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Kaushik Satapathy, Dimitrios Psaltis, Feryal Özel, Lia Medeiros, Sean T. Dougall, Chi-Kwan Chan, Maciek Wielgus, Ben S. Prather, George N. Wong, Charles F. Gammie, Kazunori Akiyama, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Richard Anantua, Keiichi Asada, Rebecca Azulay, Anne-Kathrin Baczko, David Ball, Mislav Baloković, John Barrett, Bradford A. Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Wilfred Boland, Katherine L. Bouman, Geoffrey C. Bower, Hope Boyce, Michael Bremer, Christiaan D. Brinkerink, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamente, Do-Young Byun, John E. Carlstrom, Andrew Chael, Koushik Chatterjee, Shami Chatterjee, Ming-Tang Chen, Yongjun Chen, Ilje Cho, Pierre Christian, John E. Conway, James M. Cordes, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, Gregory Desvignes, Jason Dexter, Sheperd S. Doeleman, Ralph P. Eatough, Heino Falcke, Joseph Farah, Vincent L. Fish, Ed Fomalont, H. Alyson Ford, Raquel Fraga-Encinas, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Roberto García, Olivier Gentaz, Boris Georgiev, Ciriaco Goddi, Roman Gold, Arturo I. Gómez-Ruiz, José L. Gómez, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, Daryl Haggard, Michael H. Hecht, Ronald Hesper, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang, David H. Hughes, Shiro Ikeda, Makoto Inoue, Sara Issaoun, David J. James, Buell T. Jannuzi, Michael Janssen, Britton Jeter, Wu Jiang, Alejandra Jimenez-Rosales, Michael D. Johnson, Svetlana Jorstad, Taehyun Jung, Mansour Karami, Ramesh Karuppusamy, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Dong-Jin Kim, Jae-Young Kim, Jongsoo Kim, Junhan Kim, Motoki Kino, Jun Yi Koay, Yutaro Kofuji, Patrick M. Koch, Shoko Koyama, Carsten Kramer, Michael Kramer, Thomas P. Krichbaum, Cheng-Yu Kuo, Tod R. Lauer, Sang-Sung Lee, Aviad Levis, Yan-Rong Li, Zhiyuan Li, Michael Lindqvist, Rocco Lico, Greg Lindahl, Jun Liu, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, Andrei P. Lobanov, Laurent Loinard, Colin Lonsdale, Ru-Sen Lu, Nicholas R. MacDonald, Jirong Mao, Nicola Marchili, Sera Markoff, Daniel P. Marrone, Alan P. Marscher, Iván Martí-Vidal, Satoki Matsushita, Lynn D. Matthews, Karl M. Menten, Izumi Mizuno, Yosuke Mizuno, James M. Moran, Kotaro Moriyama, Monika Moscibrodzka, Cornelia Müller, Alejandro Mus Mejías, Gibwa Musoke, Hiroshi Nagai, Neil M. Nagar, Masanori Nakamura, Ramesh Narayan, Gopal Narayanan, Iniyan Natarajan, Antonios Nathanail, Joey Neilsen, Roberto Neri, Chunchong Ni, Aristeidis Noutsos, Michael A. Nowak, Hiroki Okino, Héctor Olivares, Gisela N. Ortiz-León, Tomoaki Oyama, Daniel C. M. Palumbo, Jongho Park, Nimesh Patel, Ue-Li Pen, Dominic W. Pesce, Vincent Piétu, Richard Plambeck, Aleksandar PopStefanija, Oliver Porth, Felix M. Pötzl, Jorge A. Preciado-López, Hung-Yi Pu, Venkatessh Ramakrishnan, Ramprasad Rao, Mark G. Rawlings, Alexander W. Raymond, Luciano Rezzolla, Bart Ripperda, Freek Roelofs, Alan Rogers, Eduardo Ros, Mel Rose, Arash Roshanineshat, Helge Rottmann, Alan L. Roy, Chet Ruszczyk, Kazi L. J. Rygl, Salvador Sánchez, David Sánchez-Arguelles, Mahito Sasada, Tuomas Savolainen, F. Peter Schloerb, Karl-Friedrich Schuster, Lijing Shao, Zhiqiang Shen, Des Small, Bong Won Sohn, Jason SooHoo, He Sun, Fumie Tazaki, Alexandra J. Tetarenko, Paul Tiede, Remo P. J. Tilanus, Michael Titus, Kenji Toma, Pablo Torne, Efthalia Traianou, Tyler Trent, Sascha Trippe, Ilse van Bemmel, Huib Jan van Langevelde, Daniel R. van Rossum, Jan Wagner, Derek Ward-Thompson, John Wardle, Jonathan Weintroub, Norbert Wex, Robert Wharton, Kaj Wiik, Qingwen Wu, Doosoo Yoon, André Young, Ken Young, Ziri Younsi, Feng Yuan, Ye-Fei Yuan, J. Anton Zensus, Guang-Yao Zhao, Shan-Shan Zhao, Ministerio de Ciencia e Innovación (España), European Commission, National Science Foundation (US), Academy of Finland, Agencia Nacional de Investigación y Desarrollo (Chile), National Natural Science Foundation of China, National Key Research and Development Program (China), National Aeronautics and Space Administration (US), Ministry of Science and Technology (Taiwan), High Energy Astrophys. & Astropart. Phys (API, FNWI), Department of Electronics and Nanoengineering, Aalto-yliopisto, Aalto University, Astronomy, Satapathy, K., Psaltis, D., Ozel, F., Medeiros, L., Dougall, S. T., Chan, C. -K., Wielgus, M., Prather, B. S., Wong, G. N., Gammie, C. F., Akiyama, K., Alberdi, A., Alef, W., Algaba, J. C., Anantua, R., Asada, K., Azulay, R., Baczko, A. -K., Ball, D., Balokovic, M., Barrett, J., Benson, B. A., Bintley, D., Blackburn, L., Blundell, R., Boland, W., Bouman, K. L., Bower, G. C., Boyce, H., Bremer, M., Brinkerink, C. D., Brissenden, R., Britzen, S., Broderick, A. E., Broguiere, D., Bronzwaer, T., Bustamente, S., Byun, D. -Y., Carlstrom, J. E., Chael, A., Chatterjee, K., Chatterjee, S., Chen, M. -T., Chen, Y., Cho, I., Christian, P., Conway, J. E., Cordes, J. M., Crawford, T. M., Crew, G. B., Cruz-Osorio, A., Cui, Y., Davelaar, J., De Laurentis, M., Deane, R., Dempsey, J., Desvignes, G., Dexter, J., Doeleman, S. S., Eatough, R. P., Falcke, H., Farah, J., Fish, V. L., Fomalont, E., Ford, H. A., Fraga-Encinas, R., Friberg, P., Fromm, C. M., Fuentes, A., Galison, P., Garcia, R., Gentaz, O., Georgiev, B., Goddi, C., Gold, R., Gomez-Ruiz, A. I., Gomez, J. L., Gu, M., Gurwell, M., Hada, K., Haggard, D., Hecht, M. H., Hesper, R., Ho, L. C., Ho, P., Honma, M., Huang, C. -W. L., Huang, L., Hughes, D. H., Ikeda, S., Inoue, M., Issaoun, S., James, D. J., Jannuzi, B. T., Janssen, M., Jeter, B., Jiang, W., Jimenez-Rosales, A., Johnson, M. D., Jorstad, S., Jung, T., Karami, M., Karuppusamy, R., Kawashima, T., Keating, G. K., Kettenis, M., Kim, D. -J., Kim, J. -Y., Kim, J., Kino, M., Koay, J. Y., Kofuji, Y., Koch, P. M., Koyama, S., Kramer, C., Kramer, M., Krichbaum, T. P., Kuo, C. -Y., Lauer, T. R., Lee, S. -S., Levis, A., Li, Y. -R., Li, Z., Lindqvist, M., Lico, R., Lindahl, G., Liu, J., Liu, K., Liuzzo, E., Lo, W. -P., Lobanov, A. P., Loinard, L., Lonsdale, C., Lu, R. -S., Macdonald, N. R., Mao, J., Marchili, N., Markoff, S., Marrone, D. P., Marscher, A. P., Marti-Vidal, I., Matsushita, S., Matthews, L. D., Menten, K. M., Mizuno, I., Mizuno, Y., Moran, J. M., Moriyama, K., Moscibrodzka, M., Muller, C., Mejias, A. M., Musoke, G., Nagai, H., Nagar, N. M., Nakamura, M., Narayan, R., Narayanan, G., Natarajan, I., Nathanail, A., Neilsen, J., Neri, R., Ni, C., Noutsos, A., Nowak, M. A., Okino, H., Olivares, H., Ortiz-Leon, G. N., Oyama, T., Palumbo, D. C. M., Park, J., Patel, N., Pen, U. -L., Pesce, D. W., Pietu, V., Plambeck, R., Popstefanija, A., Porth, O., Potzl, F. M., Preciado-Lopez, J. A., Pu, H. -Y., Ramakrishnan, V., Rao, R., Rawlings, M. G., Raymond, A. W., Rezzolla, L., Ripperda, B., Roelofs, F., Rogers, A., Ros, E., Rose, M., Roshanineshat, A., Rottmann, H., Roy, A. L., Ruszczyk, C., Rygl, K. L. J., Sanchez, S., Sanchez-Arguelles, D., Sasada, M., Savolainen, T., Schloerb, F. P., Schuster, K. -F., Shao, L., Shen, Z., Small, D., Sohn, B. W., Soohoo, J., Sun, H., Tazaki, F., Tetarenko, A. J., Tiede, P., Tilanus, R. P. J., Titus, M., Toma, K., Torne, P., Traianou, E., Trent, T., Trippe, S., Van Bemmel, I., Van Langevelde, H. J., Van Rossum, D. R., Wagner, J., Ward-Thompson, D., Wardle, J., Weintroub, J., Wex, N., Wharton, R., Wiik, K., Wu, Q., Yoon, D., Young, A., Young, K., Younsi, Z., Yuan, F., Yuan, Y. -F., Zensus, J. A., Zhao, G. -Y., and Zhao, S. -S.
- Subjects
High Energy Astrophysical Phenomena (astro-ph.HE) ,Astronomy ,SCHEME ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astronomy and Astrophysics ,F500 ,MASS ,Black hole physics ,NOISE ,ENERGY ,Space and Planetary Science ,ACCRETION ,Astrophysics - High Energy Astrophysical Phenomena ,High energy astrophysics ,GRMHD SIMULATIONS - Abstract
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.--Full list of authors: Satapathy, Kaushik; Psaltis, Dimitrios; Özel, Feryal; Medeiros, Lia; Dougall, Sean T.; Chan, Chi-Kwan; Wielgus, Maciek; Prather, Ben S.; Wong, George N.; Gammie, Charles F.; Akiyama, Kazunori; Alberdi, Antxon; Alef, Walter; Algaba, Juan Carlos; Anantua, Richard; Asada, Keiichi; Azulay, Rebecca; Baczko, Anne-Kathrin; Ball, David; Baloković, Mislav; Barrett, John; Benson, Bradford A.; Bintley, Dan; Blackburn, Lindy; Blundell, Raymond; Boland, Wilfred; Bouman, Katherine L.; Bower, Geoffrey C.; Boyce, Hope; Bremer, Michael; Brinkerink, Christiaan D.; Brissenden, Roger; Britzen, Silke; Broderick, Avery E.; Broguiere, Dominique; Bronzwaer, Thomas; Bustamente, Sandra; Byun, Do-Young; Carlstrom, John E.; Chael, Andrew; Chatterjee, Koushik; Chatterjee, Shami; Chen, Ming-Tang; Chen, Yongjun; Cho, Ilje; Christian, Pierre; Conway, John E.; Cordes, James M.; Crawford, Thomas M.; Crew, Geoffrey B.; Cruz-Osorio, Alejandro; Cui, Yuzhu; Davelaar, Jordy; De Laurentis, Mariafelicia; Deane, Roger; Dempsey, Jessica; Desvignes, Gregory; Dexter, Jason; Doeleman, Sheperd S.; Eatough, Ralph P.; Falcke, Heino; Farah, Joseph; Fish, Vincent L.; Fomalont, Ed; Ford, H. Alyson; Fraga-Encinas, Raquel; Friberg, Per; Fromm, Christian M.; Fuentes, Antonio; Galison, Peter; García, Roberto; Gentaz, Olivier; Georgiev, Boris; Goddi, Ciriaco; Gold, Roman; Gómez-Ruiz, Arturo I.; Gómez, José L.; Gu, Minfeng; Gurwell, Mark; Hada, Kazuhiro; Haggard, Daryl; Hecht, Michael H.; Hesper, Ronald; Ho, Luis C.; Ho, Paul; Honma, Mareki; Huang, Chih-Wei L.; Huang, Lei; Hughes, David H.; Ikeda, Shiro; Inoue, Makoto; Issaoun, Sara; James, David J.; Jannuzi, Buell T.; Janssen, Michael; Jeter, Britton; Jiang, Wu; Jimenez-Rosales, Alejandra; Johnson, Michael D.; Jorstad, Svetlana; Jung, Taehyun; Karami, Mansour; Karuppusamy, Ramesh; Kawashima, Tomohisa; Keating, Garrett K.; Kettenis, Mark; Kim, Dong-Jin; Kim, Jae-Young; Kim, Jongsoo; Kim, Junhan; Kino, Motoki; Koay, Jun Yi; Kofuji, Yutaro; Koch, Patrick M.; Koyama, Shoko; Kramer, Carsten; Kramer, Michael; Krichbaum, Thomas P.; Kuo, Cheng-Yu; Lauer, Tod R.; Lee, Sang-Sung; Levis, Aviad; Li, Yan-Rong; Li, Zhiyuan; Lindqvist, Michael; Lico, Rocco; Lindahl, Greg; Liu, Jun; Liu, Kuo; Liuzzo, Elisabetta; Lo, Wen-Ping; Lobanov, Andrei P.; Loinard, Laurent; Lonsdale, Colin; Lu, Ru-Sen; MacDonald, Nicholas R.; Mao, Jirong; Marchili, Nicola; Markoff, Sera; Marrone, Daniel P.; Marscher, Alan P.; Martí-Vidal, Iván; Matsushita, Satoki; Matthews, Lynn D.; Menten, Karl M.; Mizuno, Izumi; Mizuno, Yosuke; Moran, James M.; Moriyama, Kotaro; Moscibrodzka, Monika; Müller, Cornelia; Mejías, Alejandro Mus; Musoke, Gibwa; Nagai, Hiroshi; Nagar, Neil M.; Nakamura, Masanori; Narayan, Ramesh; Narayanan, Gopal; Natarajan, Iniyan; Nathanail, Antonios; Neilsen, Joey; Neri, Roberto; Ni, Chunchong; Noutsos, Aristeidis; Nowak, Michael A.; Okino, Hiroki; Olivares, Héctor; Ortiz-León, Gisela N.; Oyama, Tomoaki; Palumbo, Daniel C. M.; Park, Jongho; Patel, Nimesh; Pen, Ue-Li; Pesce, Dominic W.; Piétu, Vincent; Plambeck, Richard; PopStefanija, Aleksandar; Porth, Oliver; Pötzl, Felix M.; Preciado-López, Jorge A.; Pu, Hung-Yi; Ramakrishnan, Venkatessh; Rao, Ramprasad; Rawlings, Mark G.; Raymond, Alexander W.; Rezzolla, Luciano; Ripperda, Bart; Roelofs, Freek; Rogers, Alan; Ros, Eduardo; Rose, Mel; Roshanineshat, Arash; Rottmann, Helge; Roy, Alan L.; Ruszczyk, Chet; Rygl, Kazi L. J.; Sánchez, Salvador; Sánchez-Arguelles, David; Sasada, Mahito; Savolainen, Tuomas; Schloerb, F. Peter; Schuster, Karl-Friedrich; Shao, Lijing; Shen, Zhiqiang; Small, Des; Sohn, Bong Won; SooHoo, Jason; Sun, He; Tazaki, Fumie; Tetarenko, Alexandra J.; Tiede, Paul; Tilanus, Remo P. J.; Titus, Michael; Toma, Kenji; Torne, Pablo; Traianou, Efthalia; Trent, Tyler; Trippe, Sascha; van Bemmel, Ilse; van Langevelde, Huib Jan; van Rossum, Daniel R.; Wagner, Jan; Ward-Thompson, Derek; Wardle, John; Weintroub, Jonathan; Wex, Norbert; Wharton, Robert; Wiik, Kaj; Wu, Qingwen; Yoon, Doosoo; Young, André; Young, Ken; Younsi, Ziri; Yuan, Feng; Yuan, Ye-Fei; Zensus, J. Anton; Zhao, Guang-Yao; Zhao, Shan-Shan., The black hole images obtained with the Event Horizon Telescope (EHT) are expected to be variable at the dynamical timescale near their horizons. For the black hole at the center of the M87 galaxy, this timescale (5–61 days) is comparable to the 6 day extent of the 2017 EHT observations. Closure phases along baseline triangles are robust interferometric observables that are sensitive to the expected structural changes of the images but are free of station-based atmospheric and instrumental errors. We explored the day-to-day variability in closure-phase measurements on all six linearly independent nontrivial baseline triangles that can be formed from the 2017 observations. We showed that three triangles exhibit very low day-to-day variability, with a dispersion of ∼3°–5°. The only triangles that exhibit substantially higher variability (∼90°–180°) are the ones with baselines that cross the visibility amplitude minima on the u–v plane, as expected from theoretical modeling. We used two sets of general relativistic magnetohydrodynamic simulations to explore the dependence of the predicted variability on various black hole and accretion-flow parameters. We found that changing the magnetic field configuration, electron temperature model, or black hole spin has a marginal effect on the model consistency with the observed level of variability. On the other hand, the most discriminating image characteristic of models is the fractional width of the bright ring of emission. Models that best reproduce the observed small level of variability are characterized by thin ring-like images with structures dominated by gravitational lensing effects and thus least affected by turbulence in the accreting plasmas. © 2022. The Author(s). Published by the American Astronomical Society., This work was supported, in part, by the NSF PIRE award 1743747 and NASA ATP award 80NSSC20K0521. L.M. acknowledges support from an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award No. AST-1903847. M.W. acknowledges the support of the Black Hole Initiative at Harvard University, which is funded by grants from the John Templeton Foundation and the Gordon and Betty Moore Foundation to Harvard University. All ray tracing calculations for Set A were performed with the El Gato GPU cluster at the University of Arizona that is funded by NSF award 1228509. All analyses for Set B were performed on CyVerse, supported by NSF grants DBI-0735191, DBI-1265383, and DBI-1743442. The EHT Collaboration thanks the following organizations and programs: the Academy of Finland (projects 274477, 284495, 312496, and 315721); the Agencia Nacional de Investigación y Desarrollo, Chile via NCN19058 (TITANs) and Fondecyt 3190878; the Alexander von Humboldt Stiftung; an Alfred P. Sloan Research Fellowship; Allegro, the European ALMA Regional Centre node in the Netherlands, the NL astronomy research network NOVA, and the astronomy institutes of the University of Amsterdam, Leiden University, and Radboud University; the black hole Initiative at Harvard University, through a grant (60477) from the John Templeton Foundation; the China Scholarship Council; Consejo Nacional de Ciencia y Tecnología (Mexico, projects U0004-246083, U0004-259839, F0003-272050, M0037-279006, F0003-281692, 104497, 275201, and 263356); the Delaney Family via the Delaney Family John A. Wheeler Chair at Perimeter Institute; Dirección General de Asuntos del Personal Académico-Universidad Nacional Autónoma de México (projects IN112417 and IN112820); the European Research Council Synergy Grant "BlackHoleCam: Imaging the Event Horizon of Black Holes" (grant 610058); the Generalitat Valenciana postdoctoral grant APOSTD/2018/177 and GenT Program (project CIDEGENT/2018/021); MICINN Research Project PID2019-108995GB-C22; the Gordon and Betty Moore Foundation (grant GBMF-3561); the Istituto Nazionale di Fisica Nucleare sezione di Napoli, iniziative specifiche TEONGRAV; the International Max Planck Research School for Astronomy and Astrophysics at the Universities of Bonn and Cologne; Joint Princeton/Flatiron and Joint Columbia/Flatiron Postdoctoral Fellowships; research at the Flatiron Institute is supported by the Simons Foundation; the Japanese Government (Monbukagakusho: MEXT) Scholarship; the Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for JSPS Research Fellowship (JP17J08829); the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (CAS; grants QYZDJ-SSW-SLH057, QYZDJSSW-SYS008, and ZDBS-LY-SLH011); the Leverhulme Trust Early Career Research Fellowship; the Max-Planck-Gesellschaft (MPG); the Max-Planck Partner Group of the MPG and the CAS; the MEXT/JSPS KAKENHI (grants 18KK0090, JP18K13594, JP18K03656, JP18H03721, 18K03709, 18H01245, and 25120007); the Malaysian Fundamental Research Grant Scheme (FRGS). FRGS/1/2019/STG02/UM/02/6; the MIT International Science and Technology Initiatives Funds; the Ministry of Science and Technology (MOST) of Taiwan (105-2112-M-001-025-MY3, 106-2112-M-001-011, 106-2119- M-001-027, 107-2119-M-001-017, 107-2119-M-001-020, 107-2119-M-110-005, 108-2112-M-001-048, and 109-2124-M-001-005); the National Aeronautics and Space Administration (NASA; Fermi Guest Investigator grant 80NSSC20K1567, NASA Astrophysics Theory Program grant 80NSSC20K0527, and NASA NuSTAR award 80NSSC20K0645); the National Institute of Natural Sciences of Japan; the National Key Research and Development Program of China (grants 2016YFA0400704 and 2016YFA0400702); the National Science Foundation (NSF; grants AST-0096454, AST-0352953, AST-0521233, AST-0705062, AST-0905844, AST-0922984, AST-1126433, AST-1140030, DGE-1144085, AST-1207704, AST-1207730, AST-1207752, MRI-1228509, OPP-1248097, AST-1310896, AST-1555365, AST-1615796, AST-1715061, AST-1716327, AST-1903847, and AST-2034306); the Natural Science Foundation of China (grants 11573051, 11633006, 11650110427, 10625314, 11721303, 11725312, 11933007, 11991052, and 11991053); a fellowship of China Postdoctoral Science Foundation (2020M671266); the Natural Sciences and Engineering Research Council of Canada (NSERC; including a Discovery Grant and the NSERC Alexander Graham Bell Canada Graduate Scholarships-Doctoral Program); the National Youth Thousand Talents Program of China; the National Research Foundation of Korea (the Global PhD Fellowship Grant: grants NRF-2015H1A2A1033752 and 2015- R1D1A1A01056807; the Korea Research Fellowship Program: NRF-2015H1D3A1066561 and Basic Research Support Grant 2019R1F1A1059721); the Netherlands Organization for Scientific Research VICI award (grant 639.043.513) and Spinoza Prize SPI 78-409; the New Scientific Frontiers with Precision Radio Interferometry Fellowship awarded by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Technology of South Africa; the Onsala Space Observatory (OSO) national infrastructure, for the provisioning of its facilities/observational support (OSO receives funding through the Swedish Research Council under grant 2017–00648) the Perimeter Institute for Theoretical Physics (research at Perimeter Institute is supported by the Government of Canada through the Department of Innovation, Science, and Economic Development and by the Province of Ontario through the Ministry of Research, Innovation, and Science); the Spanish Ministerio de Economía y Competitividad (grants PGC2018-098915-B-C21, AYA2016-80889-P, and PID2019-108995GB-C21); the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofísica de Andalucía (SEV-2017–0709); the Toray Science Foundation; the Consejería de Economía, Conocimiento, Empresas y Universidad of the Junta de Andalucía (grant P18-FR-1769), the Consejo Superior de Investigaciones Científicas (grant 2019AEP112); the US Department of Energy (USDOE) through the Los Alamos National Laboratory (operated by Triad National Security, LLC), for the National Nuclear Security Administration of the USDOE (Contract 89233218CNA000001); the European Union's Horizon 2020 research and innovation program under grant agreement No. 730562 RadioNet; ALMA North America Development Fund; the Academia Sinica; Chandra DD7-18089X and TM6-17006X; the GenT Program (Generalitat Valenciana) Project CIDEGENT/2018/021. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), supported by NSF grant ACI-1548562, and CyVerse, supported by NSF grants DBI-0735191, DBI-1265383, and DBI-1743442. XSEDE Stampede2 resource at TACC was allocated through TG-AST170024 and TG-AST080026N. XSEDE JetStream resource at PTI and TACC was allocated through AST170028. The simulations were performed in part on the SuperMUC cluster at the LRZ in Garching, on the LOEWE cluster in CSC in Frankfurt, and on the HazelHen cluster at the HLRS in Stuttgart. This research was enabled, in part, by support provided by Compute Ontario (http://computeontario.ca), Calcul Quebec (http://www.calculquebec.ca), and Compute Canada (http://www.computecanada.ca). We thank the staff at the participating observatories, correlation centers, and institutions for their enthusiastic support. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2016.1.01154.V. ALMA is a partnership of the European Southern Observatory (ESO; Europe, representing its member states), NSF, and the National Institutes of Natural Sciences of Japan, together with National Research Council (Canada), MOST (Taiwan), the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA; Taiwan), and the Korea Astronomy and Space Science Institute (KASI; Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, Associated Universities, Inc. (AUI)/NRAO, and the National Astronomical Observatory of Japan (NAOJ). The NRAO is a facility of the NSF operated under cooperative agreement by AUI. APEX is a collaboration between the Max-Planck-Institut für Radioastronomie (Germany), ESO, and the OSO (Sweden). The SMA is a joint project between the SAO and ASIAA and is funded by the Smithsonian Institution and the Academia Sinica. The JCMT is operated by the East Asian Observatory on behalf of the NAOJ, ASIAA, and KASI, as well as the Ministry of Finance of China, CAS, and the National Key R&D Program (No. 2017YFA0402700) of China. Additional funding support for the JCMT is provided by the Science and Technologies Facility Council (UK) and participating universities in the UK and Canada. The LMT is a project operated by the Instituto Nacional de Astrófisica, Óptica, y Electrónica (Mexico) and the University of Massachusetts at Amherst (USA). The IRAM 30 m telescope in Pico Veleta, Spain is operated by IRAM and supported by CNRS (Centre National de la Recherche Scientifique, France), MPG (Max-Planck Gesellschaft, Germany), and IGN (Instituto Geográfico Nacional, Spain). The SMT is operated by the Arizona Radio Observatory, a part of the Steward Observatory of the University of Arizona, with financial support of operations from the State of Arizona and financial support for instrumentation development from the NSF. The SPT is supported by the NSF through grant PLR-1248097. Partial support is also provided by the NSF Physics Frontier Center grant PHY-1125897 to the Kavli Institute of Cosmological Physics at the University of Chicago, the Kavli Foundation, and the Gordon and Betty Moore Foundation grant GBMF 947. The SPT hydrogen maser was provided on loan from the GLT, courtesy of ASIAA. The EHTC has received generous donations of FPGA chips from Xilinx Inc., under the Xilinx University Program. The EHTC has benefited from technology shared under an open-source license by the Collaboration for Astronomy Signal Processing and Electronics Research. The EHT project is grateful to T4Science and Microsemi for their assistance with hydrogen masers. This research has made use of NASA's Astrophysics Data System. We gratefully acknowledge the support provided by the extended staff of the ALMA, both from the inception of the ALMA Phasing Project through the observational campaigns of 2017 and 2018.
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39. Weak Turbulence and Quasilinear Diffusion for Relativistic Wave-Particle Interactions Via a Markov Approach
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Oliver Allanson, Thomas Elsden, Clare Watt, Thomas Neukirch, Science & Technology Facilities Council, and University of St Andrews. Applied Mathematics
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Astronomy ,Geophysics. Cosmic physics ,QB1-991 ,F500 ,Weak turbulence ,plasma waves ,Markov ,QB Astronomy ,Relativistic ,QA Mathematics ,QA ,quasilinear theory ,QC ,QB ,QC801-809 ,Space plasma ,Astronomy and Astrophysics ,Radiation belts ,space plasma ,Plasma waves ,QC Physics ,Wave-particle interactions ,relativistic ,T-DAS ,Quasilinear theory ,wave-particle interactions - Abstract
Funding: OA acknowledges financial support from the University of Exeter and from the United Kingdom Natural Environment Research Council (NERC) Independent Research Fellowship NE/V013963/1. OA and CW acknowledge financial support from the NERC Highlight Topic Grant NE/P017274/1 (Rad-Sat), and from United Kingdom Science and Technology Facilities Council (STFC) via Consolidated Grant ST/W000369/1. TE acknowledges financial support from an Early Career Fellowship, split jointly by the Leverhulme Trust (ECF2019-155) and the University of Leicester in the first instance (2019-21), but presently the University of Glasgow (2021-). TN acknowledges financial support from the STFC via Consolidated Grant ST/S000402/1. The University of Exeter cover the Open Access Publication Fee via a UKRI block grant. We derive weak turbulence and quasilinear models for relativistic charged particle dynamics in pitch-angle and energy space, due to interactions with electromagnetic waves propagating (anti-)parallel to a uniform background magnetic field. We use a Markovian approach that starts from the consideration of single particle motion in a prescribed electromagnetic field. This Markovian approach has a number of benefits, including: (i) the evident self-consistent relationship between a more general weak turbulence theory and the standard resonant diffusion quasilinear theory (as is commonly used in e.g. radiation belt and solar wind modelling); (ii) the general nature of the Fokker-Planck equation that can be derived without any prior assumptions regarding its form; (iii) the clear dependence of the form of the Fokker-Planck equation and the transport coefficients on given specific timescales. The quasilinear diffusion coefficients that we derive are not new in and of themselves, but this concise derivation and discussion of the weak turbulence and quasilinear theories using the Markovian framework is physically very instructive. The results presented herein form fundamental groundwork for future studies that consider phenomena for which some of the assumptions made in this manuscript may be relaxed. Publisher PDF
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40. Modeling the varying location of field line resonances during geomagnetic storms
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T. Elsden, T. K. Yeoman, S. J. Wharton, I. J. Rae, J. K. Sandhu, M‐T. Walach, M. K. James, D. M. Wright, and University of St Andrews. Applied Mathematics
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GE ,F300 ,F800 ,DAS ,F500 ,Physics::Geophysics ,Geophysics ,QC Physics ,Space and Planetary Science ,Physics::Space Physics ,QA Mathematics ,QA ,Physics::Atmospheric and Oceanic Physics ,QC ,GE Environmental Sciences - Abstract
Funding: T. Elsden was supported by a Leverhulme Trust Early Career Fellowship (ECF-2019-155), the University of Leicester and the University of Glasgow. I. J. Rae was supported by NERC Grants NE/P017185/1 and NE/V002554/2 and STFC Grant ST/V006320/1. T. K. Yeoman and M. K. James were supported by STFC Grant ST/S000429/1. J. K. Sandhu was supported by NERC Grants NE/P017185/2 and NE/V002554/2. M-T Walach was supported by NERC Grant NE/T000937/1. Previous observational studies have shown that the natural Alfvén frequencies of geomagnetic field lines vary significantly over the course of a geomagnetic storm, decreasing by up to 50% from their quiet time values outside the plasmasphere. This was recently demonstrated statistically using ground magnetometer observations across 132 geomagnetic storm events (Wharton et al., 2020). This then brings into question where field line resonances (FLRs) will form in storm-time conditions relative to quiet times. With storm-time radiation belt dynamics depending heavily upon wave-particle interactions, understanding how FLR locations change over the course of a storm will have important implications for this area. Using 3D magnetohydrodynamic (MHD) simulations, we investigate how changes in the Alfvén frequency continuum of the Earth's dayside magnetosphere over the course of a geomagnetic storm affect the fast-Alfvén wave coupling. By setting the model Alfvén frequencies consistent with the observations, and permitting a modest change in the plasmapause/magnetopause locations consistent with storm-time behavior, we show that FLR locations can change substantially during storms. The combined effects of higher fast waveguide frequencies and lower Alfvén frequencies during storm main phases, act together to move the FLR locations radially inwards compared to quiet times. FLRs outside of the plasmasphere are moved radially inward by 1.7 Earth radii for the cases considered. Publisher PDF
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41. Galaxy And Mass Assembly (GAMA)
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Simon P Driver, Sabine Bellstedt, Aaron S G Robotham, Ivan K Baldry, Luke J Davies, Jochen Liske, Danail Obreschkow, Edward N Taylor, Angus H Wright, Mehmet Alpaslan, Steven P Bamford, Amanda E Bauer, Joss Bland-Hawthorn, Maciej Bilicki, Matías Bravo, Sarah Brough, Sarah Casura, Michelle E Cluver, Matthew Colless, Christopher J Conselice, Scott M Croom, Jelte de Jong, Franceso D’Eugenio, Roberto De Propris, Burak Dogruel, Michael J Drinkwater, Andrej Dvornik, Daniel J Farrow, Carlos S Frenk, Benjamin Giblin, Alister W Graham, Meiert W Grootes, Madusha L P Gunawardhana, Abdolhosein Hashemizadeh, Boris Häußler, Catherine Heymans, Hendrik Hildebrandt, Benne W Holwerda, Andrew M Hopkins, Tom H Jarrett, D Heath Jones, Lee S Kelvin, Soheil Koushan, Konrad Kuijken, Maritza A Lara-López, Rebecca Lange, Ángel R López-Sánchez, Jon Loveday, Smriti Mahajan, Martin Meyer, Amanda J Moffett, Nicola R Napolitano, Peder Norberg, Matt S Owers, Mario Radovich, Mojtaba Raouf, John A Peacock, Steven Phillipps, Kevin A Pimbblet, Cristina Popescu, Khaled Said, Anne E Sansom, Mark Seibert, Will J Sutherland, Jessica E Thorne, Richard J Tuffs, Ryan Turner, Arjen van der Wel, Eelco van Kampen, Steve M Wilkins, ITA, USA, GBR, FRA, DEU, AUS, BEL, IND, NLD, POL, ZAF, and Kapteyn Astronomical Institute
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VELOCITY DISPERSIONS ,galaxies: Distances and redshift ,F500 ,Astrophysics::Cosmology and Extragalactic Astrophysics ,distances and redshift ,distances and redshift, galaxies ,luminosity function, mass function, cosmological parameters, Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics ,galaxies: Luminosity function, mass function ,fundamental parameters, galaxies ,TARGET SELECTION ,surveys ,LARGE-SCALE STRUCTURE ,galaxies: Fundamental parameters ,galaxies ,Luminosity function, mass function [galaxies] ,STAR-FORMING GALAXIES ,Astrophysics::Solar and Stellar Astrophysics ,fundamental parameters [galaxies] ,distances and redshift [galaxies] ,luminosity function ,cosmological parameters ,Infrarot-Astrophysik - Abteilung Hinton ,PHOTOMETRIC REDSHIFTS ,QC ,Astrophysics::Galaxy Astrophysics ,catalogues ,QB ,luminosity function [galaxies] ,REDSHIFT SURVEY ,METALLICITY RELATION ,galaxies: Luminosity function ,Astronomy and Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Physics and Astronomy ,Space and Planetary Science ,LUMINOSITY FUNCTION ,mass function ,DIGITAL SKY SURVEY ,MILKY-WAY ,Astrophysics::Earth and Planetary Astrophysics ,fundamental parameters ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
In Galaxy And Mass Assembly Data Release 4 (GAMA DR4), we make available our full spectroscopic redshift sample. This includes 248682 galaxy spectra, and, in combination with earlier surveys, results in 330542 redshifts across five sky regions covering ~250deg^2. The redshift density, is the highest available over such a sustained area, has exceptionally high completeness (95 per cent to r_KIDS=19.65mag), and is well suited for the study of galaxy mergers, galaxy groups, and the low redshift (z, Comment: Accepted for publication in MNRAS. GAMA Data Release 4 is available at: http://www.gama-survey.org/dr4/
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42. Parallel Plasma Loops and the Energization of the Solar Corona
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Hardi Peter, Lakshmi Pradeep Chitta, Feng Chen, David I. Pontin, Amy R. Winebarger, Leon Golub, Sabrina L. Savage, Laurel A. Rachmeler, Ken Kobayashi, David H. Brooks, Jonathan W. Cirtain, Bart De Pontieu, David E. McKenzie, Richard J. Morton, Paola Testa, Sanjiv K. Tiwari, Robert W. Walsh, and Harry P. Warren
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Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,F300 ,F510 ,FOS: Physical sciences ,Astronomy and Astrophysics ,F500 ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
The outer atmosphere of the Sun is composed of plasma heated to temperatures well in excess of the visible surface. We investigate short cool and warm (, Accepted for publication in the Astrophysical Journal, 24 pages, 18 figures
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43. Thermal Instability-Induced Fundamental Magnetic Field Strands in the Solar Corona
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Juan Martínez-Sykora, Patrick Antolin, and Seray Şahin
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F300 ,Space and Planetary Science ,Physics::Space Physics ,Astrophysics::Solar and Stellar Astrophysics ,Astronomy and Astrophysics ,F500 - Abstract
Thermal instability is a fundamental process of astrophysical plasmas. It is expected to occur whenever the cooling is dominated by radiation and cannot be compensated for by heating. In this work, we conduct 2.5D radiation MHD simulations with the Bifrost code of an enhanced activity network in the solar atmosphere. Coronal loops are produced self-consistently, mainly through Joule heating, which is sufficiently stratified and symmetric to produce thermal nonequilibrium. During the cooling and driven by thermal instability, coronal rain is produced along the loops. Due to flux freezing, the catastrophic cooling process leading to a rain clump produces a local enhancement of the magnetic field, thereby generating a distinct magnetic strand within the loop up to a few Gauss stronger than the surrounding coronal field. These strands, which can be considered fundamental, are a few hundred kilometers in width, span most of the loop leg, and emit strongly in the UV and extreme UV (EUV), thereby establishing a link between the commonly seen rain strands in the visible spectrum with the observed EUV coronal strands at high resolution. The compression downstream leads to an increase in temperature that generates a plume-like structure, a strongly emitting spicule-like feature, and short-lived brightening in the UV during the rain impact, providing an explanation for similar phenomena seen with IRIS. Thermal instability and nonequilibrium can therefore be associated with localized and intermittent UV brightening in the transition region and chromosphere, as well as contribute to the characteristic filamentary morphology of the solar corona in the EUV.
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- 2022
44. Probing star formation and ISM properties using galaxy disk inclination : III. Evolution in dust opacity and clumpiness between redshift 0.0 < z < 0.7 constrained from UV to NIR
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van der Giessen, S.A., Leslie, S.K., Groves, B., Hodge, J.A., Popescu, Cristina, Sargent, M.T., Schinnerer, E., and Tuffs, R.J.
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DATA RELEASE ,INFRARED-EMISSION ,F500 ,Astrophysics::Cosmology and Extragalactic Astrophysics ,COSMIC DUST ,RADIATIVE-TRANSFER ,Astrophysics::Solar and Stellar Astrophysics ,NEARBY GALAXIES ,Galaxies - ISM ,Astrophysics::Galaxy Astrophysics ,evolution [galaxies] ,Ultraviolet ,LEGACY SURVEY ,ISM [galaxies] ,FORMING GALAXIES ,Star formation ,Galaxies - evolution ,Dust ,Astronomy and Astrophysics ,Extinction ,Galaxies ,Astrophysics - Astrophysics of Galaxies ,MOLECULAR GAS ,SPECTRAL ENERGY-DISTRIBUTION ,Physics and Astronomy ,Space and Planetary Science ,MILKY-WAY ,Astrophysics::Earth and Planetary Astrophysics ,dust, extinction ,star formation [galaxies] ,galaxies [ultraviolet] - Abstract
Attenuation by dust severely impacts our ability to obtain unbiased observations of galaxies, especially as the amount and wavelength dependence of the attenuation varies with the stellar mass M-*, inclination i, and other galaxy properties. In this study, we used the attenuation - inclination models in ultraviolet, optical, and near-infrared bands designed by Tuffs and collaborators to investigate the average global dust properties in galaxies as a function of M-*, the stellar mass surface density mu(*), the star-formation rate SFR, the specific star-formation rate sSFR, the star-formation main-sequence offset dMS, and the star-formation rate surface density Sigma(SFR) at redshifts z similar to 0 and z similar to 0.7. We used star-forming galaxies from the Sloan Digital Sky Survey (similar to 20 000) and Galaxy And Mass Assembly (similar to 2000) to form our low-z sample at 0.04 < z < 0.1 and star-forming galaxies from Cosmological Evolution Survey (similar to 2000) for the sample at 0.6 < z < 0.8. We found that galaxies at z similar to 0.7 have a higher optical depth tau(f)(B) and clumpiness F than galaxies at z similar to 0. The increase in F hints that the stars of z similar to 0.7 galaxies are less likely to escape their birth cloud, which might indicate that the birth clouds are larger. We also found that tau(f)(B) increases with M-* and mu(*), independent of the sample and therefore redshift. We found no clear trends in tau(f)(B) or F with the SFR, which could imply that the dust mass distribution is independent of the SFR. In turn, this would imply that the balance of dust formation and destruction is independent of the SFR. Based on an analysis of the inclination dependence of the Balmer decrement, we found that reproducing the Balmer line emission requires not only a completely optically thick dust component associated with star-forming regions, as in the standard model, but an extra component of an optically thin dust within the birth clouds. This new component implies the existence of dust inside H II regions that attenuates the Balmer emission before it escapes through gaps in the birth cloud and we found it is more important in high-mass galaxies. These results will inform our understanding of dust formation and dust geometry in star-forming galaxies across redshift., Australian Research Council FT140101202 639.042.611, Netherlands Organization for Scientific Research (NWO), Scientific Exchanges visitor fellowship IZSEZO_202357, Swiss National Science Foundation (SNSF), European Commission
- Published
- 2022
45. Prevalence of Thermal Non-Equilibrium over an Active Region
- Author
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Patrick Antolin and Seray Şahin
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,F300 ,Space and Planetary Science ,FOS: Physical sciences ,Astronomy and Astrophysics ,F500 ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
Recent observations have shown that besides the characteristic multimillion degree component, the corona also contains a large amount of cool material called coronal rain, whose clumps are 10–100 times cooler and denser than the surroundings and are often organized in larger events, termed showers. Thermal instability (TI) within a coronal loop in a state of thermal nonequilibrium (TNE) is the leading mechanism behind the formation of coronal rain but no investigation on showers exists to date. In this study, we conduct a morphological and thermodynamic multiwavelength study of coronal rain showers observed in an active region (AR) off-limb with IRIS and the Solar Dynamics Observatory, spanning chromospheric to transition region and coronal temperatures. Rain showers were found to be widespread across the AR over the 5.45 hr observing time, with an average length, width, and duration of 27.37 ± 11.95 Mm, 2.14 ± 0.74 Mm, and 35.22 ± 20.35 minutes, respectively. We find a good correspondence between showers and the cooling coronal structures consistent with the TNE–TI scenario, thereby properly identifying coronal loops in the “coronal veil”, including the strong expansion at low heights and an almost zero expansion in the corona. This agrees with previous work suggesting that the observed zero expansion in the EUV is due to specific cross-field temperature distribution. We estimate the total number of showers to be 155 ± 40, leading to a TNE volume of 4.56 ± [3.71] × 1028 cm3, i.e., on the same order of the AR volume. This suggests a prevalence of TNE over the AR indicating strongly stratified and high-frequency heating on average.
- Published
- 2022
- Full Text
- View/download PDF
46. The JCMT BISTRO Survey: Multi-wavelength polarimetry of bright regions in NGC 2071 in the far-infrared/submillimetre range, with POL-2 and HAWC+
- Author
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Lapo Fanciullo, Francisca Kemper, Kate Pattle, Patrick M Koch, Sarah Sadavoy, Simon Coudé, Archana Soam, Thiem Hoang, Takashi Onaka, Valentin J M Le Gouellec, Doris Arzoumanian, David Berry, Chakali Eswaraiah, Eun Jung Chung, Ray Furuya, Charles L H Hull, Jihye Hwang, Douglas Johnstone, Ji-hyun Kang, Kyoung Hee Kim, Florian Kirchschlager, Vera Könyves, Jungmi Kwon, Woojin Kwon, Shih-Ping Lai, Chang Won Lee, Tie Liu, A-Ran Lyo, Ian Stephens, Motohide Tamura, Xindi Tang, Derek Ward-Thompson, Anthony Whitworth, Hiroko Shinnaga, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
polarization ,FOS: Physical sciences ,Astronomy and Astrophysics ,F500 ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics - Astrophysics of Galaxies ,ISM: clouds ,submillimetre: ISM ,Space and Planetary Science ,[SDU]Sciences of the Universe [physics] ,Astrophysics of Galaxies (astro-ph.GA) ,ISM: individual objects (NGC 2071) ,ISM: magnetic fields ,Astrophysics::Galaxy Astrophysics - Abstract
Polarized dust emission is a key tracer in the study of interstellar medium and of star formation. The observed polarization, however, is a product of magnetic field structure, dust grain properties and grain alignment efficiency, as well as their variations in the line of sight, making it difficult to interpret polarization unambiguously. The comparison of polarimetry at multiple wavelengths is a possible way of mitigating this problem. We use data from HAWC+/SOFIA and from SCUBA-2/POL-2 (from the BISTRO survey) to analyse the NGC 2071 molecular cloud at 154, 214 and 850 $\mu$m. The polarization angle changes significantly with wavelength over part of NGC 2071, suggesting a change in magnetic field morphology on the line of sight as each wavelength best traces different dust populations. Other possible explanations are the existence of more than one polarization mechanism in the cloud or scattering from very large grains. The observed change of polarization fraction with wavelength, and the 214-to-154 $\mu$m polarization ratio in particular, are difficult to reproduce with current dust models under the assumption of uniform alignment efficiency. We also show that the standard procedure of using monochromatic intensity as a proxy for column density may produce spurious results at HAWC+ wavelengths. Using both long-wavelength (POL-2, 850 $\mu$m) and short-wavelength (HAWC+, $\lesssim 200\, \mu$m) polarimetry is key in obtaining these results. This study clearly shows the importance of multi-wavelength polarimetry at submillimeter bands to understand the dust properties of molecular clouds and the relationship between magnetic field and star formation., Comment: Main article: 18 pages, 11 figures. Online supplemental material: 2 pages, 3 figures
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- 2022
- Full Text
- View/download PDF
47. A Case for Electron-Astrophysics
- Author
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Satoshi Kasahara, Julia E. Stawarz, Thierry Dudok de Wit, Daniel Told, Yuri V. Khotyaintsev, Christopher S. Reynolds, Stepan Stverak, Bennett A. Maruca, David Burgess, Milan Maksimovic, Jiansen He, Owen Roberts, Joachim Saur, Robert T. Wicks, Benoit Lavraud, Shinji Saito, Olga Alexandrova, Luca Franci, Sergio Servidio, Ferdinand Plaschke, Katja Klein, Raffaella D'Amicis, Pierre Henri, Chadi S. Salem, Christopher H. K. Chen, Johan De Keyser, Daniel Verscharen, Fouad Sahraoui, Roberto Bruno, Stefaan Poedts, Observatoire de Paris - Site de Paris (OP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-École polytechnique (X)-Sorbonne Universités-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Mullard Space Science Laboratory (MSSL), University College of London [London] (UCL), University of New Hampshire (UNH), University of Northumbria at Newcastle [United Kingdom], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Queen Mary University of London (QMUL), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), INAF - Osservatorio Astrofisico di Arcetri (OAA), School of Earth and Space Sciences [Beijing], Peking University [Beijing], Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), The University of Tokyo (UTokyo), Institutet för Rymdfysik, University of Arizona, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Bartol Research Institute, University of Delaware [Newark], Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Centre for Mathematical Plasma-Astrophysics [Leuven] (CmPA), Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Maria Curie-Sklodowska University (UMCS), Institute of Astronomy, University of Cambridge, Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), National Institute of Information and Communications Technology [Tokyo, Japan] (NICT), University of California [Berkeley], University of California, Institut für Geophysik und Meteorologie [Köln], Universität zu Köln, Università della Calabria [Arcavacata di Rende] (Unical), Department of Physics [Imperial College London], Imperial College London, Czech Academy of Sciences [Prague] (CAS), Max Planck Institute for Plasma physics (IPP-MPG), Max-Planck-Gesellschaft, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Verscharen, Daniel [0000-0002-0497-1096], and Apollo - University of Cambridge Repository
- Subjects
Field (physics) ,F300 ,FOS: Physical sciences ,Electrons ,F500 ,Electron ,7. Clean energy ,01 natural sciences ,F900 ,Physics - Space Physics ,Voyage 2050 ,Physics::Plasma Physics ,0103 physical sciences ,Thermal ,[PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det] ,010306 general physics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] ,Astronomy and Astrophysics ,Plasma ,space missions ,Dissipation ,plasma astrophysics ,Physics - Plasma Physics ,Space Physics (physics.space-ph) ,[PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph] ,Computational physics ,Magnetic field ,Plasma Physics (physics.plasm-ph) ,space plasma ,Solar wind ,Astrophysics - Solar and Stellar Astrophysics ,solar wind ,Space and Planetary Science ,Physics::Space Physics ,Astrophysical plasma ,Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Instrumentation and Methods for Astrophysics ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] - Abstract
A grand-challenge problem at the forefront of physics is to understand how energy is transported and transformed in plasmas. This fundamental research priority encapsulates the conversion of plasma-flow and electromagnetic energies into particle energy, either as heat or some other form of energisation. The smallest characteristic scales, at which electron dynamics determines the plasma behaviour, are the next frontier in space and astrophysical plasma research. The analysis of astrophysical processes at these scales lies at the heart of the field of electron-astrophysics. Electron scales are the ultimate bottleneck for dissipation of plasma turbulence, which is a fundamental process not understood in the electron-kinetic regime. Since electrons are the most numerous and most mobile plasma species in fully ionised plasmas and are strongly guided by the magnetic field, their thermal properties couple very efficiently to global plasma dynamics and thermodynamics., Comment: White Paper for the Voyage 2050 Long-Term Plan in the ESA Science Programme; 27 pages
- Published
- 2022
48. The law and economics of supranationalism: the European Union and the subsidiarity principle in collective action perspective.
- Author
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Levy, Richard
- Subjects
SUPRANATIONALISM ,COLLECTIVE action -- Social aspects ,EUROPEAN Union law ,DELEGATION of authority - Abstract
This article, prepared for an issue devoted to the work of Judge Richard A. Posner, considers the implications of law and economics for the structure of supranational organizations, with particular attention to the application of collective action theory to the relationships among states in the EU. After discussing the connections between this approach and Judge Posner's work, the article describes collective action theory and its implications for our understanding of the state and of relationships among states. From this perspective, supranational organizations such as the EU can be understood as institutional structures that facilitate collective action among states by reducing the transactions and enforcement costs of making and implementing collective decisions. At the same time, the delegation of authority to supranational institutions creates agency costs for states and their peoples because the interests of the state and its people diverge from the interests of the collective in some instances. Viewed in this perspective, the institutional structure of the EU-like that of other supranational organizations or federal nation states-reflects an effort to strike a balance between collective decision making and local control so as to maximize the collective gains and minimize the resulting agency costs. Understood in these terms, various features of the EU's institutional design make sense. The ordinary legislative process permits the EU to act without the unanimous consent of member states, thus reducing transactions costs in those areas where collective action is necessary, particularly in relation to the creation and regulation of the internal market. The EU reduces enforcement costs through principles of direct applicability or effects and the supremacy of EU law, which are effective legal restraints in states governed by the rule of law. The institutional structure of the EU also incorporates a representative and deliberative process for collective action that helps control the resulting agency costs for member states and their peoples through supermajority and co-decisional requirements. The collective action perspective also illuminates the function of the subsidiarity principle and the enhanced role of national parliaments in its enforcement. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
49. Modern Grand Solar Minimum will lead to terrestrial cooling
- Author
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Valentina Zharkova
- Subjects
Solar minimum ,Field (physics) ,F300 ,Physiology ,business.industry ,F500 ,Lead (geology) ,Physiology (medical) ,Physics::Space Physics ,Astrophysics::Solar and Stellar Astrophysics ,Environmental science ,Astrophysics::Earth and Planetary Astrophysics ,Aerospace engineering ,business ,Front Matter: Editorial ,Research Article - Abstract
In this editorial I will demonstrate with newly discovered solar activity proxy-magnetic field that the Sun has entered into the modern Grand Solar Minimum (2020–2053) that will lead to a significant reduction of solar magnetic field and activity like during Maunder minimum leading to noticeable reduction of terrestrial temperature.
- Published
- 2020
50. A V-shape photonic crystal fiber polarization filter based on surface plasmon resonance effect
- Author
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Xian Zhou, Xinzhu Sang, Qiang Wu, Binbin Yan, Chao Mei, Jinhui Yuan, Yuwei Qu, Keping Long, Kuiru Wang, Chongxiu Yu, and Feng Li
- Subjects
Optical fiber ,Materials science ,F300 ,H600 ,F100 ,F200 ,Physics::Optics ,F500 ,02 engineering and technology ,Polarizing filter ,01 natural sciences ,law.invention ,010309 optics ,Optics ,law ,0103 physical sciences ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Surface plasmon resonance ,Extinction ratio ,business.industry ,021001 nanoscience & nanotechnology ,Polarization (waves) ,Surface plasmon polariton ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Wavelength ,0210 nano-technology ,business ,Photonic-crystal fiber - Abstract
In this paper, a V-shape photonic crystal fiber (PCF) polarization filter based on surface plasmon resonance (SPR) effect is proposed. With the full vector finite element method, the V-shape photonic crystal fiber polarization filter is designed, and the coupling characteristics between the core mode and surface plasmon polariton mode are analyzed. The simulation results show that the fiber parameters have significant effects on the shift and strength of the SPR wavelength. Moreover, the losses of the core modes along the Y and X polarization directions are 68904 dB/m and 858 dB/m at the SPR wavelength of 1550 nm, respectively. Finally, the extinction ratio and error-tolerant rate of extinction ratio are also analyzed. The proposed V-shape PCF polarization filter can achieve good filtering effect in the communication band and is easy to integrate with existing optical fiber communication and sensing systems.
- Published
- 2019
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