bluuebunny/crossref_metadata_2025_split huggingface dataset:
Demographics of Star-forming Galaxies since z ∼ 2.5. I. The UVJ Diagram in CANDELS
Authors: Fang Jerome J. , Faber S. M. , Koo David C. , Rodríguez-Puebla Aldo , Guo Yicheng , Barro Guillermo , Behroozi Peter , Brammer Gabriel , Chen Zhu , Dekel Avishai , Ferguson Henry C. , Gawiser Eric , Giavalisco Mauro , Kartaltepe Jeyhan , Kocevski Dale D. , Koekemoer Anton M. , McGrath Elizabeth J. , McIntosh Daniel , Newman Jeffrey A. , Pacifici Camilla , Pandya Viraj , Pérez-González Pablo G. , Primack Joel R. , Salmon Brett , Trump Jonathan R. , Weiner Benjamin , Willner S. P. , Acquaviva Viviana , Dahlen Tomas , Finkelstein Steven L. , Finlator Kristian , Fontana Adriano , Galametz Audrey , Grogin Norman A. , Gruetzbauch Ruth , Johnson Seth , Mobasher Bahram , Papovich Casey J. , Pforr Janine , Salvato Mara , Santini P. , van der Wel Arjen , Wiklind Tommy , Wuyts Stijn 
Published: May 2018

Abstract
This is the first in a series of papers examining the demographics of star-forming (SF) galaxies at 0.2 < z < 2.5 in CANDELS. We study 9100 galaxies from GOODS-S and UDS, having published values of redshifts, masses, star formation rates (SFRs), and dust attenuation (A

V
) derived from UV–optical spectral energy distribution fitting. In agreement with previous works, we find that the UVJ colors of a galaxy are closely correlated with its specific star formation rate (SSFR) and A

V
. We define rotated UVJ coordinate axes, termed S
SED and C
SED, that are parallel and perpendicular to the SF sequence and derive a quantitative calibration that predicts SSFR from C
SED with an accuracy of ∼0.2 dex. SFRs from UV–optical fitting and from UV+IR values based on Spitzer/MIPS 24 μm agree well overall, but systematic differences of order 0.2 dex exist at high and low redshifts. A novel plotting scheme conveys the evolution of multiple galaxy properties simultaneously, and dust growth, as well as star formation decline and quenching, exhibit “mass-accelerated evolution” (“downsizing”). A population of transition galaxies below the SF main sequence is identified. These objects are located between SF and quiescent galaxies in UVJ space, and have lower A

V
and smaller radii than galaxies on the main sequence. Their properties are consistent with their being in transit between the two regions. The relative numbers of quenched, transition, and SF galaxies are given as a function of mass and redshift.
The MOSDEF Survey: A Stellar Mass–SFR–Metallicity Relation Exists at z ∼ 2.3∗
Authors: Sanders Ryan L. , Shapley Alice E. , Kriek Mariska , Freeman William R. , Reddy Naveen A. , Siana Brian , Coil Alison L. , Mobasher Bahram , Davé Romeel , Shivaei Irene , Azadi Mojegan , Price Sedona H. , Leung Gene , Fetherholf Tara , Groot Laura de , Zick Tom , Fornasini Francesca M. , Barro Guillermo 
Published: May 2018

Abstract
We investigate the nature of the relation among stellar mass, star formation rate, and gas-phase metallicity (the

–SFR–Z relation) at high redshifts using a sample of 260 star-forming galaxies at z ∼ 2.3 from the MOSDEF survey. We present an analysis of the high-redshift

–SFR–Z relation based on several emission-line ratios for the first time. We show that a

–SFR–Z relation clearly exists at z ∼ 2.3. The strength of this relation is similar to predictions from cosmological hydrodynamical simulations. By performing a direct comparison of stacks of z ∼ 0 and z ∼ 2.3 galaxies, we find that z ∼ 2.3 galaxies have ∼0.1 dex lower metallicity at fixed

and SFR. In the context of chemical evolution models, this evolution of the

–SFR–Z relation suggests an increase with redshift of the mass-loading factor at fixed

, as well as a decrease in the metallicity of infalling gas that is likely due to a lower importance of gas recycling relative to accretion from the intergalactic medium at high redshifts. Performing this analysis simultaneously with multiple metallicity-sensitive line ratios allows us to rule out the evolution in physical conditions (e.g., N/O ratio, ionization parameter, and hardness of the ionizing spectrum) at fixed metallicity as the source of the observed trends with redshift and with SFR at fixed

at z ∼ 2.3. While this study highlights the promise of performing high-order tests of chemical evolution models at high redshifts, detailed quantitative comparisons ultimately await a full understanding of the evolution of metallicity calibrations with redshift.
An L Band Spectrum of the Coldest Brown Dwarf
Authors: Morley Caroline V. , Skemer Andrew J. , Allers Katelyn N. , Marley Mark. S. , Faherty Jacqueline K. , Visscher Channon , Beiler Samuel A. , Miles Brittany E. , Lupu Roxana , Freedman Richard S. , Fortney Jonathan J. , Geballe Thomas R. , Bjoraker Gordon L. 
Published: May 2018

Abstract
The coldest brown dwarf, WISE 0855, is the closest known planetary-mass, free-floating object and has a temperature nearly as cold as the solar system gas giants. Like Jupiter, it is predicted to have an atmosphere rich in methane, water, and ammonia, with clouds of volatile ices. WISE 0855 is faint at near-infrared wavelengths and emits almost all its energy in the mid-infrared. Skemer et al. presented a spectrum of WISE 0855 from 4.5–5.1 μm (M band), revealing water vapor features. Here, we present a spectrum of WISE 0855 in the L band, from 3.4–4.14 μm. We present a set of atmosphere models that include a range of compositions (metallicities and C/O ratios) and water ice clouds. Methane absorption is clearly present in the spectrum. The mid-infrared color can be better matched with a methane abundance that is depleted relative to solar abundance. We find that there is evidence for water ice clouds in the M band spectrum, and we find a lack of phosphine spectral features in both the L and M band spectra. We suggest that a deep continuum opacity source may be obscuring the near-infrared flux, possibly a deep phosphorous-bearing cloud, ammonium dihyrogen phosphate. Observations of WISE 0855 provide critical constraints for cold planetary atmospheres, bridging the temperature range between the long-studied solar system planets and accessible exoplanets. The James Webb Space Telescope will soon revolutionize our understanding of cold brown dwarfs with high-precision spectroscopy across the infrared, allowing us to study their compositions and cloud properties, and to infer their atmospheric dynamics and formation processes.
Spatiotemporal Interpolation Methods for Solar Event Trajectories
Authors: Boubrahimi Soukaina Filali , Aydin Berkay , Schuh Michael A. , Kempton Dustin , Angryk Rafal A. , Ma Ruizhe 
Published: May 2018

Abstract
This paper introduces four spatiotemporal interpolation methods that enrich complex, evolving region trajectories that are reported from a variety of ground-based and space-based solar observatories every day. Our interpolation module takes an existing solar event trajectory as its input and generates an enriched trajectory with any number of additional time–geometry pairs created by the most appropriate method. To this end, we designed four different interpolation techniques: MBR-Interpolation (Minimum Bounding Rectangle Interpolation), CP-Interpolation (Complex Polygon Interpolation), FI-Interpolation (Filament Polygon Interpolation), and Areal-Interpolation, which are presented here in detail. These techniques leverage k-means clustering, centroid shape signature representation, dynamic time warping, linear interpolation, and shape buffering to generate the additional polygons of an enriched trajectory. Using ground-truth objects, interpolation effectiveness is evaluated through a variety of measures based on several important characteristics that include spatial distance, area overlap, and shape (boundary) similarity. To our knowledge, this is the first research effort of this kind that attempts to address the broad problem of spatiotemporal interpolation of solar event trajectories. We conclude with a brief outline of future research directions and opportunities for related work in this area.
Novelty and Foreseeing Research Trends: The Case of Astrophysics and Astronomy
Authors: Varga Attila 
Published: May 2018

Abstract
Metrics based on reference lists of research articles or on keywords have been used to predict citation impact. The concept behind such metrics is that original ideas stem from the reconfiguration of the structure of past knowledge, and therefore atypical combinations in the reference lists, keywords, or classification codes indicate future high-impact research. The current paper serves as an introduction to this line of research for astronomers and also addresses some of the methodological questions in this field of innovation studies. It is still not clear if the choice of particular indexes, such as references to journals, articles, or specific bibliometric classification codes affects the relationship between atypical combinations and citation impact. To understand more aspects of the innovation process, a new metric has been devised to measure to what extent researchers are able to anticipate the changing combinatorial trends of the future. Results show that the variant of the latter anticipation scores that is based on paper combinations is a good predictor of the future citation impact of scholarly works. The study also shows that the effects of tested indexes vary with the aggregation levels that were used to construct them. A detailed analysis of combinatorial novelty in the field reveals that certain sub-fields of astronomy and astrophysics have different roles in the reconfiguration of past knowledge.
Understanding the Lomb–Scargle Periodogram
Authors: VanderPlas Jacob T. 
Published: May 2018

Abstract
The Lomb–Scargle periodogram is a well-known algorithm for detecting and characterizing periodic signals in unevenly sampled data. This paper presents a conceptual introduction to the Lomb–Scargle periodogram and important practical considerations for its use. Rather than a rigorous mathematical treatment, the goal of this paper is to build intuition about what assumptions are implicit in the use of the Lomb–Scargle periodogram and related estimators of periodicity, so as to motivate important practical considerations required in its proper application and interpretation.
High-cadence Imaging and Imaging Spectroscopy at the GREGOR Solar Telescope—A Collaborative Research Environment for High-resolution Solar Physics
Authors: Denker Carsten , Kuckein Christoph , Verma Meetu , Manrique Sergio J. González , Diercke Andrea , Enke Harry , Klar Jochen , Balthasar Horst , Louis Rohan E. , Dineva Ekaterina 
Published: May 2018

Abstract
In high-resolution solar physics, the volume and complexity of photometric, spectroscopic, and polarimetric ground-based data significantly increased in the last decade, reaching data acquisition rates of terabytes per hour. This is driven by the desire to capture fast processes on the Sun and the necessity for short exposure times “freezing” the atmospheric seeing, thus enabling ex post facto image restoration. Consequently, large-format and high-cadence detectors are nowadays used in solar observations to facilitate image restoration. Based on our experience during the “early science” phase with the 1.5 m GREGOR solar telescope (2014–2015) and the subsequent transition to routine observations in 2016, we describe data collection and data management tailored toward image restoration and imaging spectroscopy. We outline our approaches regarding data processing, analysis, and archiving for two of GREGOR’s post-focus instruments (see http://gregor.aip.de), i.e., the GREGOR Fabry–Pérot Interferometer (GFPI) and the newly installed High-Resolution Fast Imager (HiFI). The heterogeneous and complex nature of multidimensional data arising from high-resolution solar observations provides an intriguing but also a challenging example for “big data” in astronomy. The big data challenge has two aspects: (1) establishing a workflow for publishing the data for the whole community and beyond and (2) creating a collaborative research environment (CRE), where computationally intense data and postprocessing tools are colocated and collaborative work is enabled for scientists of multiple institutes. This requires either collaboration with a data center or frameworks and databases capable of dealing with huge data sets based on virtual observatory (VO) and other community standards and procedures.
Activity Analyses for Solar-type Stars Observed with Kepler. II. Magnetic Feature versus Flare Activity
Authors: He Han , Wang Huaning , Zhang Mei , Mehrabi Ahmad , Yan Yan , Yun Duo 
Published: May 2018

Abstract
The light curves of solar-type stars present both periodic fluctuation and flare spikes. The gradual periodic fluctuation is interpreted as the rotational modulation of magnetic features on the stellar surface and is used to deduce magnetic feature activity properties. The flare spikes in light curves are used to derive flare activity properties. In this paper, we analyze the light curve data of three solar-type stars (KIC 6034120, KIC 3118883, and KIC 10528093) observed with Kepler space telescope and investigate the relationship between their magnetic feature activities and flare activities. The analysis shows that: (1) both the magnetic feature activity and the flare activity exhibit long-term variations as the Sun does; (2) unlike the Sun, the long-term variations of magnetic feature activity and flare activity are not in phase with each other; (3) the analysis of star KIC 6034120 suggests that the long-term variations of magnetic feature activity and flare activity have a similar cycle length. Our analysis and results indicate that the magnetic features that dominate rotational modulation and the flares possibly have different source regions, although they may be influenced by the magnetic field generated through a same dynamo process.
OSSOS. VII. 800+ Trans-Neptunian Objects—The Complete Data Release
Authors: Bannister Michele T. , Gladman Brett J. , Kavelaars J. J. , Petit Jean-Marc , Volk Kathryn , Chen 陳英 Ying-Tung 同 , Alexandersen Mike , Gwyn Stephen D. J. , Schwamb Megan E. , Ashton Edward , Benecchi Susan D. , Cabral Nahuel , Dawson Rebekah I. , Delsanti Audrey , Fraser Wesley C. , Granvik Mikael , Greenstreet Sarah , Guilbert-Lepoutre Aurélie , Ip 葉永 Wing-Huen 烜 , Jakubik Marian , Jones R. Lynne , Kaib Nathan A. , Lacerda Pedro , Laerhoven Christa Van , Lawler Samantha , Lehner Matthew J. , Lin 林省 Hsing Wen 文 , Lykawka Patryk Sofia , Marsset Michaël , Murray-Clay Ruth , Pike Rosemary E. , Rousselot Philippe , Shankman Cory , Thirouin Audrey , Vernazza Pierre , Wang 王祥 Shiang-Yu 宇 
Published: May 2018

Abstract
The Outer Solar System Origins Survey (OSSOS), a wide-field imaging program in 2013–2017 with the Canada–France–Hawaii Telescope, surveyed 155 deg2 of sky to depths of m

r
= 24.1–25.2. We present 838 outer solar system discoveries that are entirely free of ephemeris bias. This increases the inventory of trans-Neptunian objects (TNOs) with accurately known orbits by nearly 50%. Each minor planet has 20–60 Gaia/Pan-STARRS-calibrated astrometric measurements made over 2–5 oppositions, which allows accurate classification of their orbits within the trans-Neptunian dynamical populations. The populations orbiting in mean-motion resonance with Neptune are key to understanding Neptune’s early migration. Our 313 resonant TNOs, including 132 plutinos, triple the available characterized sample and include new occupancy of distant resonances out to semimajor axis a ∼ 130 au. OSSOS doubles the known population of the nonresonant Kuiper Belt, providing 436 TNOs in this region, all with exceptionally high-quality orbits of a uncertainty σ

a
≤ 0.1%; they show that the belt exists from a ≳ 37 au, with a lower perihelion bound of 35 au. We confirm the presence of a concentrated low-inclination a ≃ 44 au “kernel” population and a dynamically cold population extending beyond the 2:1 resonance. We finely quantify the survey’s observational biases. Our survey simulator provides a straightforward way to impose these biases on models of the trans-Neptunian orbit distributions, allowing statistical comparison to the discoveries. The OSSOS TNOs, unprecedented in their orbital precision for the size of the sample, are ideal for testing concepts of the history of giant planet migration in the solar system.
realfast: Real-time, Commensal Fast Transient Surveys with the Very Large Array
Authors: Law C. J. , Bower G. C. , Burke-Spolaor S. , Butler B. J. , Demorest P. , Halle A. , Khudikyan S. , Lazio T. J. W. , Pokorny M. , Robnett J. , Rupen M. P. 
Published: May 2018

Abstract
Radio interferometers have the ability to precisely localize and better characterize the properties of sources. This ability is having a powerful impact on the study of fast radio transients, where a few milliseconds of data is enough to pinpoint a source at cosmological distances. However, recording interferometric data at millisecond cadence produces a terabyte-per-hour data stream that strains networks, computing systems, and archives. This challenge mirrors that of other domains of science, where the science scope is limited by the computational architecture as much as the physical processes at play. Here, we present a solution to this problem in the context of radio transients: realfast, a commensal, fast transient search system at the Jansky Very Large Array. realfast uses a novel architecture to distribute fast-sampled interferometric data to a 32-node, 64-GPU cluster for real-time imaging and transient detection. By detecting transients in situ, we can trigger the recording of data for those rare, brief instants when the event occurs and reduce the recorded data volume by a factor of 1000. This makes it possible to commensally search a data stream that would otherwise be impossible to record. This system will search for millisecond transients in more than 1000 hr of data per year, potentially localizing several Fast Radio Bursts, pulsars, and other sources of impulsive radio emission. We describe the science scope for realfast, the system design, expected outcomes, and ways in which real-time analysis can help in other fields of astrophysics.
Robust Period Estimation Using Mutual Information for Multiband Light Curves in the Synoptic Survey Era
Authors: Huijse Pablo , Estévez Pablo A. , Förster Francisco , Daniel Scott F. , Connolly Andrew J. , Protopapas Pavlos , Carrasco Rodrigo , Príncipe José C. 
Published: May 2018

Abstract
The Large Synoptic Survey Telescope (LSST) will produce an unprecedented amount of light curves using six optical bands. Robust and efficient methods that can aggregate data from multidimensional sparsely sampled time-series are needed. In this paper we present a new method for light curve period estimation based on quadratic mutual information (QMI). The proposed method does not assume a particular model for the light curve nor its underlying probability density and it is robust to non-Gaussian noise and outliers. By combining the QMI from several bands the true period can be estimated even when no single-band QMI yields the period. Period recovery performance as a function of average magnitude and sample size is measured using 30,000 synthetic multiband light curves of RR Lyrae and Cepheid variables generated by the LSST Operations and Catalog simulators. The results show that aggregating information from several bands is highly beneficial in LSST sparsely sampled time-series, obtaining an absolute increase in period recovery rate up to 50%. We also show that the QMI is more robust to noise and light curve length (sample size) than the multiband generalizations of the Lomb–Scargle and AoV periodograms, recovering the true period in 10%–30% more cases than its competitors. A python package containing efficient Cython implementations of the QMI and other methods is provided.
On the Statistical Properties of Cospectra
Authors: Huppenkothen D. , Bachetti M. 
Published: May 2018

Abstract
In recent years, the cross-spectrum has received considerable attention as a means of characterizing the variability of astronomical sources as a function of wavelength. The cospectrum has only recently been understood as a means of mitigating instrumental effects dependent on temporal frequency in astronomical detectors, as well as a method of characterizing the coherent variability in two wavelength ranges on different timescales. In this paper, we lay out the statistical foundations of the cospectrum, starting with the simplest case of detecting a periodic signal in the presence of white noise, under the assumption that the same source is observed simultaneously in independent detectors in the same energy range. This case is especially relevant for detecting faint X-ray pulsars in detectors heavily affected by instrumental effects, including NuSTAR, Astrosat, and IXPE, which allow for even sampling and where the cospectrum can act as an effective way to mitigate dead time. We show that the statistical distributions of both single and averaged cospectra differ considerably from those for standard periodograms. While a single cospectrum follows a Laplace distribution exactly, averaged cospectra are approximated by a Gaussian distribution only for more than ∼30 averaged segments, dependent on the number of trials. We provide an instructive example of a quasi-periodic oscillation in NuSTAR and show that applying standard periodogram statistics leads to underestimated tail probabilities for period detection. We also demonstrate the application of these distributions to a NuSTAR observation of the X-ray pulsar Hercules X-1.
Le recours à l’effet différé de la censure par le Conseil constitutionnel : le point de vue de la Cour EDH
Authors: Koskas Michael 
Published: May 2018

Une utilisation justifiée et non arbitraire : telles sont les exigences formulées par la Cour européenne des droits de l’homme quant à l’usage par le Conseil constitutionnel de son pouvoir de modulation des effets dans le temps d’une déclaration d’inconstitutionnalité. Par sa décision de rejet Chessa c. France rendue le 1er mars dernier, la Cour offre ainsi une grille d’analyse innovante pour relire à nouveaux frais certaines des décisions rendues par le juge constitutionnel au cours de ces deux dernières années.