bluuebunny/crossref_metadata_2025_split huggingface dataset:
IN SITU DETECTION OF CHLORINE DIOXIDE (ClO2) IN THE RADIOLYSIS OF PERCHLORATES AND IMPLICATIONS FOR THE STABILITY OF ORGANICS ON MARS
Authors: Góbi Sándor , Bergantini Alexandre , Kaiser Ralf I. 
Published: November 2016

ABSTRACT
Magnesium perchlorate hexahydrate (Mg(ClO4)2 · 6H2O) samples were exposed to energetic electrons to investigate the products of the decomposition of perchlorates in the Martian soil and to infer their role in the degradation of organics on Mars. The samples were monitored online and in situ via infrared spectroscopy as well as electron impact (EI-QMS) and reflectron time-of-flight mass spectrometry coupled with single photon ionization (PI-ReTOF-MS). Our study reveals that besides chlorates (

) and molecular oxygen (O2), the chlorine dioxide radical (ClO2) was observed online and in situ for the first time as a radiolysis product of solid perchlorates. Chlorine dioxide, which is used on Earth as a strong oxidizing agent in water disinfection and bleaching, represents a proficient oxidizer—potentially more powerful than molecular oxygen—to explain the lack of abundant organics in the Martian soil.
SPECTRAL LINE DE-CONFUSION IN AN INTENSITY MAPPING SURVEY
Authors: Cheng Yun-Ting , Chang Tzu-Ching , Bock James , Bradford C. Matt , Cooray Asantha 
Published: November 2016

ABSTRACT
Spectral line intensity mapping (LIM) has been proposed as a promising tool to efficiently probe the cosmic reionization and the large-scale structure. Without detecting individual sources, LIM makes use of all available photons and measures the integrated light in the source confusion limit to efficiently map the three-dimensional matter distribution on large scales as traced by a given emission line. One particular challenge is the separation of desired signals from astrophysical continuum foregrounds and line interlopers. Here we present a technique to extract large-scale structure information traced by emission lines from different redshifts, embedded in a three-dimensional intensity mapping data cube. The line redshifts are distinguished by the anisotropic shape of the power spectra when projected onto a common coordinate frame. We consider the case where high-redshift [C ii] lines are confused with multiple low-redshift CO rotational lines. We present a semi-analytic model for [C ii] and CO line estimates based on the cosmic infrared background measurements, and show that with a modest instrumental noise level and survey geometry, the large-scale [C ii] and CO power spectrum amplitudes can be successfully extracted from a confusion-limited data set, without external information. We discuss the implications and limits of this technique for possible LIM experiments.
THE REST-FRAME OPTICAL SPECTROSCOPIC PROPERTIES OF LYα-EMITTERS AT z ∼ 2.5: THE PHYSICAL ORIGINS OF STRONG LYα EMISSION*
Authors: Trainor Ryan F. , Strom Allison L. , Steidel Charles C. , Rudie Gwen C. 
Published: November 2016

ABSTRACT
We present the rest-frame optical spectroscopic properties of 60 faint (R
AB ∼ 27; L ∼ 0.1 L
*) Lyα-selected galaxies (LAEs) at z ≈ 2.56. These LAEs also have rest-UV spectra of their Lyα emission line morphologies, which trace the effects of interstellar and circumgalactic gas on the escape of Lyα photons. We find that the LAEs have diverse rest-optical spectra, but their average spectroscopic properties are broadly consistent with the extreme low-metallicity end of the populations of continuum-selected galaxies selected at z ≈ 2–3. In particular, the LAEs have extremely high [O iii] λ5008/Hβ ratios (log([O iii]/Hβ) ∼ 0.8) and low [N ii] λ6585/Hα ratios (log([N ii]/Hα) < 1.15). Coupled with a detection of the [O iii] λ4364 auroral line, these measurements indicate that the star-forming regions in faint LAEs are characterized by high electron temperatures (T

e
≈ 1.8 × 104 K), low oxygen abundances (12 + log(O/H) ≈ 8.04, Z
neb ≈ 0.22Z
⊙), and high excitations with respect to their more luminous continuum-selected analogs. Several of our faintest LAEs have line ratios consistent with even lower metallicities, including six with 12 + log(O/H) ≈ 6.9–7.4 (Z
neb ≈ 0.02–0.05Z
⊙). We interpret these observations in light of new models of stellar evolution (including binary interactions) that have been shown to produce long-lived populations of hot, massive stars at low metallicities. We find that strong, hard ionizing continua are required to reproduce our observed line ratios, suggesting that faint galaxies are efficient producers of ionizing photons and important analogs of reionization-era galaxies. Furthermore, we investigate the physical trends accompanying Lyα emission across the largest current sample of combined Lyα and rest-optical galaxy spectroscopy, including both the 60 KBSS-Lyα LAEs and 368 more luminous galaxies at similar redshifts. We find that the net Lyα emissivity (parameterized by the Lyα equivalent width) is strongly correlated with nebular excitation and ionization properties and weakly correlated with dust attenuation, suggesting that metallicity plays a strong role in determining the observed properties of these galaxies by modulating their stellar spectra, nebular excitation, and dust content.
DIFFUSE AURORA ON GANYMEDE DRIVEN BY ELECTROSTATIC WAVES
Authors: Singhal R. P. , Tripathi A. K. , Halder S. , II O. N. Singh 
Published: November 2016

ABSTRACT
The role of electrostatic electron cyclotron harmonic (ECH) waves in producing diffuse auroral emission O i 1356 Å on Ganymede is investigated. Electron precipitation flux entering the atmosphere of Ganymede due to pitch-angle diffusion by ECH waves into the atmospheric loss-cone is calculated. The analytical yield spectrum approach for electron energy degradation in gases is used for calculating diffuse auroral intensities. It is found that calculated O i 1356 Å intensity resulting from the precipitation of magnetospheric electrons observed near Ganymede is insufficient to account for the observed diffuse auroral intensity. This is in agreement with estimates made in earlier works. Heating and acceleration of ambient electrons by ECH wave turbulence near the magnetic equator on the field line connecting Ganymede and Jupiter are considered. Two electron distribution functions are used to simulate the heating effect by ECH waves. Use of a Maxwellian distribution with temperature 100 eV can produce about 50–70 Rayleigh O i 1356 Å intensities, and the kappa distribution with characteristic energy 50 eV also gives rise to intensities with similar magnitude. Numerical experiments are performed to study the effect of ECH wave spectral intensity profile, ECH wave amplitude, and temperature/characteristic energy of electron distribution functions on the calculated diffuse auroral intensities. The proposed missions, joint NASA/ESA Jupiter Icy Moon Explorer and the present JUNO mission to Jupiter, would provide new data to constrain the ECH wave and other physical parameters near Ganymede. These should help confirm the findings of the present study.
EXPLORING DAMPED Lyα SYSTEM HOST GALAXIES USING GAMMA-RAY BURSTS
Authors: Toy Vicki L. , Cucchiara Antonino , Veilleux Sylvain , Fumagalli Michele , Rafelski Marc , Rahmati Alireza , Cenko S. Bradley , Capone John I. , Pasham Dheeraj R. 
Published: November 2016

ABSTRACT
We present a sample of 45 Damped Lyα system (DLA;

) counterparts (33 detections, 12 upper limits) which host gamma-ray bursts (GRB-DLAs) in order to investigate star formation and metallicity within galaxies hosting DLAs. Our sample spans

and is nearly three times larger than any previously detected DLA counterparts survey based on quasar line-of-sight searches (QSO-DLAs). We report star formation rates (SFRs) from rest-frame UV photometry and spectral energy distribution modeling. We find that DLA counterpart SFRs are not correlated with either redshift or H i column density. Thanks to the combination of Hubble Space Telescope and ground-based observations, we also investigate DLA host star formation efficiency. Our GRB-DLA counterpart sample spans both higher efficiency and low efficiency star formation regions compared to the local Kennicutt–Schmidt relation, local star formation laws, and

cosmological simulations. We also compare the depletion times of our DLA hosts sample to other objects in the local universe; our sample appears to deviate from the star formation efficiencies measured in local spiral and dwarf galaxies. Furthermore, we find similar efficiencies as local inner disks, SMC, and Lyman-break galaxy outskirts. Finally, our enrichment time measurements show a spread of systems with under- and over-abundance of metals, which may suggest that these systems had episodic star formation and a metal enrichment/depletion as a result of strong stellar feedback and/or metal inflow/outflow.
GENESIS OF INTERPLANETARY INTERMITTENT TURBULENCE: A CASE STUDY OF ROPE–ROPE MAGNETIC RECONNECTION
Authors: Chian Abraham C.-L. , Feng Heng Q. , Hu Qiang , Loew Murray H. , Miranda Rodrigo A. , Muñoz Pablo R. , Sibeck David G. , Wu De J. 
Published: November 2016

ABSTRACT
In a recent paper, the relation between current sheet, magnetic reconnection, and turbulence at the leading edge of an interplanetary coronal mass ejection was studied. We report here the observation of magnetic reconnection at the interface region of two interplanetary magnetic flux ropes. The front and rear boundary layers of three interplanetary magnetic flux ropes are identified, and the structures of magnetic flux ropes are reconstructed by the Grad–Shafranov method. A quantitative analysis of the reconnection condition and the degree of intermittency reveals that rope–rope magnetic reconnection is the most likely site for genesis of interplanetary intermittency turbulence in this event. The dynamic pressure pulse resulting from this reconnection triggers the onset of a geomagnetic storm.
SDSS-IV MaNGA: A SERENDIPITOUS OBSERVATION OF A POTENTIAL GAS ACCRETION EVENT
Authors: Cheung Edmond , Stark David V. , Huang Song , Rubin Kate H. R. , Lin Lihwai , Tremonti Christy , Zhang Kai , Yan Renbin , Bizyaev Dmitry , Boquien Médéric , Brownstein Joel R. , Drory Niv , Gelfand Joseph D. , Knapen Johan H. , Maiolino Roberto , Malanushenko Olena , Masters Karen L. , Merrifield Michael R. , Pace Zach , Pan Kaike , Riffel Rogemar A. , Roman-Lopes Alexandre , Rujopakarn Wiphu , Schneider Donald P. , Stott John P. , Thomas Daniel , Weijmans Anne-Marie 
Published: November 2016

ABSTRACT
The nature of warm, ionized gas outside of galaxies may illuminate several key galaxy evolutionary processes. A serendipitous observation by the MaNGA survey has revealed a large, asymmetric Hα complex with no optical counterpart that extends ≈8″ (≈6.3 kpc) beyond the effective radius of a dusty, starbursting galaxy. This Hα extension is approximately three times the effective radius of the host galaxy and displays a tail-like morphology. We analyze its gas-phase metallicities, gaseous kinematics, and emission-line ratios and discuss whether this Hα extension could be diffuse ionized gas, a gas accretion event, or something else. We find that this warm, ionized gas structure is most consistent with gas accretion through recycled wind material, which could be an important process that regulates the low-mass end of the galaxy stellar mass function.
THE MASSIVE PROTOSTELLAR CLUSTER NGC 6334I AT 220 au RESOLUTION: DISCOVERY OF FURTHER MULTIPLICITY, DIVERSITY, AND A HOT MULTI-CORE
Authors: Brogan C. L. , Hunter T. R. , Cyganowski C. J. , Chandler C. J. , Friesen R. , Indebetouw R. 
Published: November 2016

ABSTRACT
We present Very Large Array and Atacama Large Millimeter/submillimeter Array imaging of the deeply embedded protostellar cluster NGC 6334I from 5 cm to 1.3 mm at angular resolutions as fine as 0.″17 (220 au). The dominant hot core MM1 is resolved into seven components at 1.3 mm, clustered within a radius of 1000 au. Four of the components have brightness temperatures >200 K, radii ∼300 au, minimum luminosities ∼104
L
⊙, and must be centrally heated. We term this new phenomenon a “hot multi-core.” Two of these objects also exhibit compact free–free emission at longer wavelengths, consistent with a hypercompact H ii region (MM1B) and a jet (MM1D). The spatial kinematics of the water maser emission centered on MM1D are consistent with it being the origin of the high-velocity bipolar molecular outflow seen in CO. The close proximity of MM1B and MM1D (440 au) suggests a proto-binary or a transient bound system. Several components of MM1 exhibit steep millimeter spectral energy distributions indicative of either unusual dust spectral properties or time variability. In addition to resolving MM1 and the other hot core (MM2) into multiple components, we detect five new millimeter and two new centimeter sources. Water masers are detected for the first time toward MM4A, confirming its membership in the protocluster. With a 1.3 mm brightness temperature of 97 K coupled with a lack of thermal molecular line emission, MM4A appears to be a highly optically thick 240 L
⊙ dust core, possibly tracing a transient stage of massive protostellar evolution. The nature of the strongest water maser source CM2 remains unclear due to its combination of non-thermal radio continuum and lack of dust emission.
THE SPACE WEATHER OF PROXIMA CENTAURI b
Authors: Garraffo C. , Drake J. J. , Cohen O. 
Published: November 2016

ABSTRACT
A planet orbiting in the “habitable zone” of our closest neighboring star, Proxima Centauri, has recently been discovered, and the next natural question is whether or not Proxima b is “habitable.” Stellar winds are likely a source of atmospheric erosion that could be particularly severe in the case of M dwarf habitable zone planets that reside close to their parent star. Here, we study the stellar wind conditions that Proxima b experiences over its orbit. We construct 3D MHD models of the wind and magnetic field around Proxima Centauri using a surface magnetic field map for a star of the same spectral type and scaled to match the observed ∼600 G surface magnetic field strength of Proxima. We examine the wind conditions and dynamic pressure over different plausible orbits that sample the constrained parameters of the orbit of Proxima b. For all the parameter space explored, the planet is subject to stellar wind pressures of more than 2000 times those experienced by Earth from the solar wind. During an orbit, Proxima b is also subject to pressure changes of 1–3 orders of magnitude on timescales of a day. Its magnetopause standoff distance consequently undergoes sudden and periodic changes by a factor of 2–5. Proxima b will traverse the interplanetary current sheet twice each orbit, and likely crosses into regions of subsonic wind quite frequently. These effects should be taken into account in any physically realistic assessment or prediction of its atmospheric reservoir, characteristics, and loss.
Porosity estimation at depths below the borehole bottom from resistivity logs and electromagnetic resistivity
Authors: Spichak Viacheslav V. , Zakharova Olga K. 
Published: November 2016

ABSTRACTA neural network approach to porosity prediction below the well bottom from either the electrical resistivity logs or electromagnetic resistivity profiles is developed using the data from Soultz‐sous‐Forets area (France). It is shown that the neural network approach enables the porosity to be predicted at the depths below the bottom of the borehole from the resistivity well‐logging data and by resistivity profiles determined by inversion of the electromagnetic sounding data collected in the vicinity of the well. The results indicate that the forecasts based on the electrical logging data are more accurate (average relative errors being equal to 3%–5%) when the target depths do not exceed the double length of the well log used for calibration. In the absence of the resistivity logs at target depths or when the target to well depth ratio is large enough, the forecasts based on the electromagnetic resistivity data are more preferable.
A comparison between 2D azimuthal and 3D resistivity imaging techniques in determining the subsurface fracture zones within Abu‐Jir Fault Zone, Southwest Karbala, Central Iraq
Authors: Al‐Zubedi Ahmed Srdah , Thabit Jassim M. 
Published: November 2016

ABSTRACTThis experimental study presents a comparison between two‐dimensional azimuthal and three‐dimensional electrical resistivity imaging techniques at a given location within the Abu‐Jir Fault Zone, Central Iraq. The aim is to examine which one is a better technique in one order to study the subsurface fracture zones and to use it within and outside the fault zone. Our results show that the two‐dimensional azimuthal imaging technique is quite successful in imaging the structural geology, particularly for effective identification and delineation of the subsurface fracture zones in all directions, whereas the three‐dimensional imaging technique, carried out using data acquired in parallel two‐dimensional imaging lines, gives limited and distorted images about these zones because the Y‐spacing between the survey lines is quite small compared to the length of these lines. The two‐dimensional azimuthal technique can be useful in deep investigations to determine the extent of the structures, particularly in areas with unknown geological and structural settings.
Strictly horizontal lateral parameter correlation for 1D inverse modelling of large datasets
Authors: Christensen Niels B. 
Published: November 2016

ABSTRACTThis paper presents new developments to the lateral parameter correlation method, a method that can be used to invoke lateral smoothness in model sections of one‐dimensional inversion models. The lateral parameter correlation method has three steps. First, all datasets are inverted individually. Next, a laterally smooth version of each model parameter is found by solving a simple constrained inversion problem by postulating identity between the uncorrelated and correlated parameters and solving the equations including a model covariance matrix that ensures lateral smoothness. As a final step, all sounding data are reinverted with the correlated model parameter values as a priori values to produce models that better fit the data. Because the method separates inversion and correlation, it is much faster than methods where the inversion and correlation are solved simultaneously. The new development to the lateral parameter correlation method presented in this paper is an option to perform a strictly horizontal correlation, thereby avoiding the model artefacts sometimes seen when correlating along layers, namely that formations tend to follow the topography. Furthermore, a solution to the intractable computation times arising with large datasets is formulated, employing a tessellation of the plane and an averaging scheme within the subareas that reduces the size of the numerical lateral parameter correlation inversion problem while maintaining correct correlation within a very large area. In a field example, correlation along layers and the new strictly horizontal correlation are compared, and it is demonstrated that the horizontal correlation removes the above mentioned artefacts that can appear when correlating along layers. The lateral parameter correlation method is very flexible and is capable of correlating models from inversion of different data types, including information from boreholes, and it lends itself easily to “embarrassingly parallel” computation.
1D sequential inversion of portable multi‐configuration electromagnetic induction data
Authors: Guillemoteau Julien , Simon François‐Xavier , Lück Erika , Tronicke Jens 
Published: November 2016

ABSTRACTWe present an algorithm that performs sequentially one‐dimensional inversion of subsurface magnetic permeability and electrical conductivity by using multi‐configuration electromagnetic induction sensor data. The presented method is based on the conversion of the in‐phase and out‐of‐phase data into effective magnetic permeability and electrical conductivity of the equivalent homogeneous half‐space. In the case of small‐offset systems, such as portable electromagnetic induction sensors, for which in‐phase and out‐of‐phase data are moderately coupled, the effective half‐space magnetic permeability and electrical conductivity can be inverted sequentially within an iterative scheme. We test and evaluate the proposed inversion strategy using synthetic and field examples. First, we apply it to synthetic data for some highly magnetic environments. Then, the method is tested on real field data acquired in a basaltic environment to image a formation of archaeological interest. These examples demonstrate that a joint interpretation of in‐phase and out‐of‐phase data leads to a better characterisation of the subsurface in magnetic environments such as volcanic areas.
Estimation of sediment texture from spectral induced polarisation data using cluster and principal component analysis
Authors: Inzoli Silvia , Giudici Mauro , Huisman Johan Alexander 
Published: November 2016

ABSTRACTSpectral induced polarisation data are usually interpreted with simple models in order to derive petrophysical relationships between electrical and sedimentological properties, such as texture, clay content, and permeability. The aim of this work is to explore the value of spectral induced polarisation in addition to conventional direct‐current resistivity measurements for determining textural properties of saturated samples collected from alluvial deposits. For this, an advanced data processing approach that combines cluster and principal component analysis was developed and applied to integral parameters derived from Debye decomposition of spectral induced polarisation data. This data processing procedure allowed identifying groups of samples with a similar spectral induced polarisation response and to derive a characteristic grain‐size distribution for each group of samples. The method to estimate the grain‐size distribution from spectral induced polarisation data was successfully validated using independent sediment samples. The remaining uncertainty in the estimation of sediment texture from spectral induced polarisation data was attributed to the effect of pore size distribution and mineralogy, which were not considered in the present work but can be added in the future within the same conceptual workflow.