Search Our Scientific Publications & Authors

Nat Commun 2019 Apr 15;10(1):1758. Epub 2019 Apr 15.

Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, UK.

The properties of supersonic, compressible plasma turbulence determine the behavior of many terrestrial and astrophysical systems. In the interstellar medium and molecular clouds, compressible turbulence plays a vital role in star formation and the evolution of our galaxy. Observations of the density and velocity power spectra in the Orion B and Perseus molecular clouds show large deviations from those predicted for incompressible turbulence. Read More

J Chem Phys 2019 Apr;150(14):141103

Institut des Sciences Moléculaires d'Orsay (ISMO), UMR 8214 CNRS, Université Paris-Sud, Université Paris-Saclay, F-91405 Orsay Cedex, France.

The hydroxyl free radical, OH, is one of the most important radicals in atmospheric and interstellar chemistry, and its cation plays a role in the reactions leading to HO formation. Knowledge of the photoionization efficiency of the OH radical is crucial to properly model the water photochemical cycle of atmospheres and astrophysical objects. Using a gas-phase radical source based on a single H-abstraction reaction combined with a photoelectron/photoion imaging coincidence spectrometer coupled with synchrotron radiation, we recorded the OH photoion yield over the 12. Read More

Phys Rev Lett 2019 Mar;122(12):121802

Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

The axion is a promising dark matter candidate, which was originally proposed to solve the strong-CP problem in particle physics. To date, the available parameter space for axion and axionlike particle dark matter is relatively unexplored, particularly at masses m_{a}≲1  μeV. ABRACADABRA is a new experimental program to search for axion dark matter over a broad range of masses, 10^{-12}≲m_{a}≲10^{-6}  eV. Read More

Phys Rev Lett 2019 Mar;122(12):121101

Department of Physics and Astronomy, University of California, Los Angeles Los Angeles, California 90095-1547, USA.

Neutron-rich material ejected from neutron star-neutron star (NS-NS) and neutron star-black-hole (NS-BH) binary mergers is heated by nuclear processes to temperatures of a few hundred keV, resulting in a population of electron-positron pairs. Some of the positrons escape from the outer layers of the ejecta. We show that the population of low-energy positrons produced by NS-NS and NS-BH mergers in the Milky Way can account for the observed 511-keV line from the Galactic center (GC). Read More

Philos Trans A Math Phys Eng Sci 2019 Apr;377(2142):20180153

Leiden Observatory , Leiden University , Niels Bohrweg 2 , 2300CA Leiden , The Netherlands.

The demand on simulation software in astrophysics has dramatically increased over the last decades. This increase is driven by improvements in observational data and computer hardware. At the same time, computers have become more complicated to program due to the introduction of more parallelism and hybrid hardware. Read More

Phys Rev Lett 2019 Mar;122(11):111101

Center for Computational Relativity and Gravitation, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, New York 14623, USA.

We use population inference to explore the impact that uncertainties in the distribution of binary black holes (BBH) have on the astrophysical gravitational-wave background (AGWB). Our results show that the AGWB monopole is sensitive to the nature of the BBH population (particularly the local merger rate), while the anisotropic C_{ℓ} spectrum is only modified to within a few percent, at a level which is insignificant compared to other sources of uncertainty (such as cosmic variance). This is very promising news for future observational studies of the AGWB, as it shows that (i) the monopole can be used as a new probe of the population of compact objects throughout cosmic history, complementary to direct observations by LIGO and Virgo and (ii) we are able to make surprisingly robust predictions for the C_{ℓ} spectrum, even with only very approximate knowledge of the black hole population. Read More

Nat Commun 2019 04 3;10(1):1504. Epub 2019 Apr 3.

College of Science and Engineering, School of Mathematics and Physics, Kanazawa University, Kakuma, Kanazawa, Ishikawa, 920-1192, Japan.

Long duration gamma-ray bursts (GRBs), the brightest events since the Big Bang itself, are believed to originate in an ultra-relativistic jet breaking out from a massive stellar envelope. Despite decades of study, there is still no consensus on their emission mechanism. One unresolved question is the origin of the tight correlation between the spectral peak energy and peak luminosity discovered in observations. Read More

Phys Rev E 2019 Feb;99(2-1):023108

Department of Mechanical Engineering and the Center for Energy Research, Jacobs School of Engineering, University of California, San Diego 92093, USA.

We report on experiments and modeling on a rotating confined liquid that is forced by circumferential jets coaxial with the rotation axis, wherein system-scale secondary flows are observed to emerge. The jets are evenly divided in number between inlets and outlets and have zero net mass transport. For low forcing strengths the sign of this flow depends on the sign of a sloped end cap, which simulates a planetary β plane. Read More

Phys Rev Lett 2019 Mar;122(8):085001

Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA.

We are reporting the observation of the breakdown of electrons' degeneracy and emergence of classical statistics in the simplest element: metallic deuterium. We have studied the optical reflectance, shock velocity, and temperature of dynamically compressed liquid deuterium up to its Fermi temperature T_{F}. Above the insulator-metal transition, the optical reflectance shows the distinctive temperature-independent resistivity saturation, which is prescribed by Mott's minimum metallic limit, in agreement with previous experiments. Read More

Phys Rev Lett 2019 Mar;122(9):092701

GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany.

We report the first measurement of low-energy proton-capture cross sections of ^{124}Xe in a heavy-ion storage ring. ^{124}Xe^{54+} ions of five different beam energies between 5.5 and 8 AMeV were stored to collide with a windowless hydrogen target. Read More

Phys Chem Chem Phys 2019 Apr 1;21(15):8015-8021. Epub 2019 Apr 1.

213 Smith Chemistry Building, The University of Memphis, Memphis, 38152, TN, USA.

The formation of phosphorous-containing polycyclic aromatic hydrocarbons (PAPHs) in astrophysical contexts is proposed and analyzed by means of computational methods [B3LYP-D3BJ/ma-def2-TZVPP, MP2-F12, CCSD-F12b and CCSD(T)-F12b levels of theory]. A "bottom-up" approach based on a radical-neutral reaction scheme between acetylene (CH) and the CP radical was used investigating: (a) the synthesis of the first PAPH (CHP) "phosphinine"; (b) PAPH growth by addition of CH to the CHP radical; (c) PAPH synthesis by addition reactions of one CP radical and nCH to a neutral PAH. Results show: (I) the formation of the phosphinine radical has a strong thermodynamic tendency (-133. Read More

J Phys Chem A 2019 Apr 29;123(14):3068-3073. Epub 2019 Mar 29.

Max-Born-Institut fr Nichtlineare Optik und Kurzzeitspektroskopie , Max-Born-Strasse 2A , D-12489 Berlin , Germany.

Rapid energy transfer from electronic to nuclear degrees of freedom underlies many biological processes and astrophysical observations. The efficiency of this energy transfer depends strongly on the complex interplay between electronic and nuclear motions. In this study, we report two-color pump-probe experiments that probe the relaxation dynamics of highly excited cationic states of naphthalene, a prototypical polycyclic aromatic hydrocarbon molecule, which are produced using wavelength-selected, ultrashort extreme ultraviolet pulses. Read More

Life (Basel) 2019 Mar 16;9(1). Epub 2019 Mar 16.

Institut de Chimie de Nice, Université Côte d'Azur, CNRS, UMR 7272, 06108 Nice, France.

The biomolecular homochirality in living organisms has been investigated for decades, but its origin remains poorly understood. It has been shown that circular polarized light (CPL) and other energy sources are capable of inducing small enantiomeric excesses (s) in some primary biomolecules, such as amino acids or sugars. Since the first findings of amino acids in carbonaceous meteorites, a scenario in which essential chiral biomolecules originate in space and are delivered by celestial bodies has arisen. Read More

Mon Not R Astron Soc 2019 May 26;485(2):2492-2504. Epub 2019 Feb 26.

Lawrence Berkeley National Lab, Berkeley, CA 94720, USA.

Previous studies have shown the filamentary structures in the cosmic web influence the alignments of nearby galaxies. We study this effect in the LOWZ sample of the Sloan Digital Sky Survey using the 'Cosmic Web Reconstruction' filament catalogue. We find that LOWZ galaxies exhibit a small but statistically significant alignment in the direction parallel to the orientation of nearby filaments. Read More

Phys Rev Lett 2019 Feb;122(7):071103

Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.

The dark matter density distribution in small-scale astrophysical objects may indicate that dark matter is self-interacting, while observations from clusters of galaxies suggest that the corresponding cross section depends on the velocity. Using a model-independent approach, we show that resonant self-interacting dark matter can naturally explain such a behavior. In contrast to what is often assumed, this does not require a light mediator. Read More

Phys Rev Lett 2019 Feb;122(7):074502

InPhyNi, UMR CNRS 7010, Nice, France.

Many turbulent flows undergo drastic and abrupt configuration changes with huge impacts. As a paradigmatic example we study the multistability of jet dynamics in a barotropic beta plane model of atmosphere dynamics. It is considered as the Ising model for Jupiter troposphere dynamics. Read More

Geophys Res Lett 2019 Jan 8;46(1):19-27. Epub 2019 Jan 8.

Laboratory for Atmospheric and Space Physics University of Colorado Boulder Boulder CO USA.

We compare electron and UV observations mapping to the same location in Jupiter's northern polar region, poleward of the main aurora, during Juno perijove 5. Simultaneous peaks in UV brightness and electron energy flux are identified when observations map to the same location at the same time. The downward energy flux during these simultaneous observations was not sufficient to generate the observed UV brightness; the upward energy flux was. Read More

J Chem Phys 2019 Feb;150(8):084301

Institut Charles Gerhardt, Université de Montpellier, UMR-CNRS 5253, 34095 Montpellier, France.

We report state-to-state quasi-classical trajectory rate constants for the D + H reactive collision, using the accurate H global potential energy surface of Mielke et al. [J. Chem. Read More

Phys Rev Lett 2019 Feb;122(6):061103

Institute of Physics, Sachivalaya Marg, Sainik School Post, Bhubaneswar 751005, India.

Astrophysical searches for new long-range interactions complement collider searches for new short-range interactions. Conveniently, neutrino flavor oscillations are keenly sensitive to the existence of long-ranged flavored interactions between neutrinos and electrons, motivated by lepton-number symmetries of the standard model. For the first time, we probe them using TeV-PeV astrophysical neutrinos and accounting for all large electron repositories in the local and distant Universe. Read More

Phys Rev Lett 2019 Feb;122(5):051101

INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy.

The escape of cosmic rays from the Galaxy is expected to shape their spectrum inside the Galaxy. Yet, this phenomenon is very poorly understood and, in the absence of a physical description, it is usually modeled as a free escape from a given boundary, typically located at a few kiloparsec distance from the Galactic disc. We show that the assumption of free escape leads to the conclusion that the cosmic ray current propagating in the circumgalactic medium is responsible for a nonresonant cosmic ray induced instability that in turn leads to the generation of a magnetic field of strength ∼2×10^{-8}  G on a scale ∼10  kpc around our Galaxy. Read More

Phys Rev Lett 2019 Feb;122(5):055101

JILA, University of Colorado and NIST, 440 UCB, Boulder, Colorado 80309, USA.

Electron and ion energization (i.e., heating and nonthermal acceleration) is a fundamental, but poorly understood, outcome of plasma turbulence. Read More

Phys Rev Lett 2019 Feb;122(5):051102

Department of Physics and Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin, Madison, Wisconsin 53706, USA.

High-energy neutrino emission has been predicted for several short-lived astrophysical transients including gamma-ray bursts (GRBs), core-collapse supernovae with choked jets, and neutron star mergers. IceCube's optical and x-ray follow-up program searches for such transient sources by looking for two or more muon neutrino candidates in directional coincidence and arriving within 100 s. The measured rate of neutrino alerts is consistent with the expected rate of chance coincidences of atmospheric background events and no likely electromagnetic counterparts have been identified in Swift follow-up observations. Read More

Chem Soc Rev 2019 Apr;48(8):2293-2314

Wellesley College, Chemistry, 106 Central Street, Wellesley, Massachusetts, USA.

In 2016, unambiguous evidence for the presence of the amino acid glycine, an important prebiotic molecule, was deduced based on in situ mass-spectral studies of the coma surrounding cometary ice. This finding is significant because comets are thought to have preserved the icy grains originally found in the interstellar medium prior to solar system formation. Energetic processing of cosmic ices via photochemistry and radiation chemistry is thought to be the dominant mechanism for the extraterrestrial synthesis of prebiotic molecules. Read More

Sci Rep 2019 Feb 22;9(1):2588. Epub 2019 Feb 22.

High Temperature Gasdynamics Laboratory, Stanford University, Stanford, California, 94305, USA.

Instabilities play a prominent role in determining the inherent structure and properties of magnetized plasma jets spanning both laboratory and astrophysical settings. The manner in which prominent unstable modes dynamically evolve remains key to understanding plasma behavior and control. In astrophysical phenomena, self-similar jets are observed to propagate over vast distances while avoiding breakup caused by unstable mode growth. Read More

Phys Rev Lett 2019 Feb;122(4):041102

INFN TIFPA, I-38123 Povo, Trento, Italy.

Precision measurements of cosmic ray positrons are presented up to 1 TeV based on 1.9 million positrons collected by the Alpha Magnetic Spectrometer on the International Space Station. The positron flux exhibits complex energy dependence. Read More

Phys Rev Lett 2019 Feb;122(4):041101

Center for Cosmology and AstroParticle Physics (CCAPP), The Ohio State University, Columbus, Ohio 43210, USA.

Neutrinos are key to probing the deep structure of matter and the high-energy Universe. Yet, until recently, their interactions had only been measured at laboratory energies up to about 350 GeV. An opportunity to measure their interactions at higher energies opened up with the detection of high-energy neutrinos in IceCube, partially of astrophysical origin. Read More

Nat Commun 2019 02 14;10(1):740. Epub 2019 Feb 14.

Department of Physics and Astronomy, University of Iowa, Iowa City, IA, 52242, USA.

How turbulent energy is dissipated in weakly collisional space and astrophysical plasmas is a major open question. Here, we present the application of a field-particle correlation technique to directly measure the transfer of energy between the turbulent electromagnetic field and electrons in the Earth's magnetosheath, the region of solar wind downstream of the Earth's bow shock. The measurement of the secular energy transfer from the parallel electric field as a function of electron velocity shows a signature consistent with Landau damping. Read More

Astrobiology 2019 Feb 14. Epub 2019 Feb 14.

15 Eurospace, Paris, France.

To ensure that scientific investments in space exploration are not compromised by terrestrial contamination of celestial bodies, special care needs to be taken to preserve planetary conditions for future astrobiological exploration. Significant effort has been made and is being taken to address planetary protection in the context of inner Solar System exploration. In particular for missions to Mars, detailed internationally accepted guidelines have been established. Read More

Space Sci Rev 2018 02 13;214(1). Epub 2017 Dec 13.

NASA Goddard Space Flight Center, Greenbelt, MD, USA.

OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This article describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS-REx spacecraft sampling hardware was maintained at level 100 A/2 and <180 ng/cm of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Read More

Opt Lett 2019 Feb;44(3):511-513

In this Letter, a Tm-Ho codoped tellurite glass microsphere laser in the 1.47 μm wavelength region is described. Using a traditional tapered microfiber-microsphere coupling method, multimode and single-mode lasing around the wavelength of 1. Read More

Astrobiology 2019 Jan 17. Epub 2019 Jan 17.

1 INAF - Osservatorio Astrofisico di Catania, Catania, Italy.

We describe the results obtained on a set of organic samples that have been part of the experiment "Photochemistry on the Space Station (PSS)" on the EXPOSE-R2 mission conducted on the EXPOSE-R facility situated outside the International Space Station (ISS). The organic samples were prepared in the Catania laboratory by 200 keV He irradiation of N:CH:CO icy mixtures deposited at 17 K, on vacuum UV (VUV) transparent MgF windows. This organic material contains different chemical groups, including triple CN bonds, that are thought to be of interest for astrobiology. Read More

Sci Rep 2019 Jan 10;9(1):29. Epub 2019 Jan 10.

CNR-IPCF, Istituto per i Processi Chimico-Fisici, I-98158, Messina, Italy.

Modeling optical tweezers in the T-matrix formalism has been of key importance for accurate and efficient calculations of optical forces and their comparison with experiments. Here we extend this formalism to the modeling of chiral optomechanics and optical tweezers where chiral light is used for optical manipulation and trapping of optically active particles. We first use the Bohren decomposition to deal with the light scattering of chiral light on optically active particles. Read More

Living Rev Relativ 2019 18;22(1). Epub 2018 Dec 18.

Department of Physics, The University of Texas at Dallas, Richardson, TX 75080 USA.

We review recent developments and results in testing general relativity (GR) at cosmological scales. The subject has witnessed rapid growth during the last two decades with the aim of addressing the question of cosmic acceleration and the dark energy associated with it. However, with the advent of precision cosmology, it has also become a well-motivated endeavor by itself to test gravitational physics at cosmic scales. Read More

Proc Natl Acad Sci U S A 2019 01 4;116(4):1185-1194. Epub 2019 Jan 4.

Rudolf Peierls Centre for Theoretical Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom.

In a collisionless, magnetized plasma, particles may stream freely along magnetic field lines, leading to "phase mixing" of their distribution function and consequently, to smoothing out of any "compressive" fluctuations (of density, pressure, etc.). This rapid mixing underlies Landau damping of these fluctuations in a quiescent plasma-one of the most fundamental physical phenomena that makes plasma different from a conventional fluid. Read More

Phys Rev Lett 2018 Dec;121(25):255101

Department of Astronomy and Columbia Astrophysics Laboratory, Columbia University, New York, New York 10027, USA.

Due to its ubiquitous presence, turbulence is often invoked to explain the origin of nonthermal particles in astrophysical sources of high-energy emission. With particle-in-cell simulations, we study decaying turbulence in magnetically dominated (or, equivalently, "relativistic") pair plasmas. We find that the generation of a power-law particle energy spectrum is a generic by-product of relativistic turbulence. Read More

Phys Rev Lett 2018 Dec;121(25):255001

Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, D-24098 Kiel, Germany.

The accurate description of electrons at extreme density and temperature is of paramount importance for, e.g., the understanding of astrophysical objects and inertial confinement fusion. Read More

J Quant Spectrosc Radiat Transf 2018 Jan 7;205:80-90. Epub 2017 Oct 7.

Special Astrophysical Observatory of the Russian Academy of Sciences, 369167 Nizhnij Arkhyz, Russia.

We summarize unique aperture data on the degree of linear polarization observed for distant comets C/2010 S1, C/2010 R1, C/2011 KP36, C/2012 J1, C/2013 V4, and C/2014 A4 with heliocentric distances exceeding 3 AU. Observations have been carried out at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences (Nizhnij Arkhyz, Russia) during the period from 2011 to 2016. The measured negative polarization proves to be significantly larger in absolute value than what is typically observed for comets close to the Sun. Read More

Phys Chem Chem Phys 2019 Jan 3;21(3):1443-1453. Epub 2019 Jan 3.

LSMA, Université Tunis El-Manar, Tunis, Tunisia.

Among the closed-shell hydrocarbons, the carbenes c- and l-CH are the lightest ones to display a permanent electric dipole moment and be detectable by rotational spectroscopy. The cyclic form, cyclopropenylidene, is ubiquitous in the InterStellar Matter (ISM) of the Milky Way and external galaxies. As such, it serves as a marker to help in characterizing the physical conditions of the ISM. Read More

Phys Chem Chem Phys 2019 Jan 2;21(3):1428-1434. Epub 2019 Jan 2.

Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622, Villeurbanne, France.

A main objective in the synthesis of prebiotic compounds is to remain consistent with reasonable geochemical scenarios, while avoiding concomitant formation of undesirable by-products. In this context, 2-aminothiazole has shown enhanced selectivity in the addition reaction with sugars promoting interest in this sulfur species compared to its oxygenated analogue, 2-aminooxazole. More generally, the role of sulfur in prebiotic chemistry needs to be widely investigated with regard to the numerous sulfur-containing molecules detected recently in different astrophysical environments. Read More

Chaos 2018 Dec;28(12):123107

Department of Physics, Jahangirnagar University, Savar, Dhaka 1342, Bangladesh.

A nonlinear Schrödinger equation is derived to investigate the modulational instability of ion-acoustic (IA) waves (IAWs) in a double pair plasma system containing adiabatic positive and negative ion fluids along with super-thermal electrons and positrons. The analytical analysis predicts two types of modes, viz., fast ( ) and slow ( ) IA modes. Read More

Phys Rev Lett 2018 Dec;121(23):235002

Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA.

Magnetized inertial fusion experiments are approaching regimes where the radial transport is dominated by collisions between magnetized ions, providing an opportunity to exploit effects usually associated with steady-state magnetic fusion. In particular, the low-density hotspot characteristic of magnetized liner inertial fusion results in diamagnetic and thermal frictions, which can demix thermalized ash from fuel, accelerating the fusion reaction. For reactor regimes in which there is a substantial burnup of the fuel, increases in the fusion energy yield on the order of 5% are possible. Read More

Nat Commun 2018 12 18;9(1):5276. Epub 2018 Dec 18.

NASA Ames Research Center, MS 245-6, Moffett Field, CA, 94035, USA.

Sugars and their derivatives are essential to all terrestrial life. Their presence in meteorites, together with amino acids, nucleobases, amphiphiles, and other compounds of biological importance, may have contributed to the inventory of organics that played a role in the emergence of life on Earth. Sugars, including ribose (the sugar of RNA), and other sugar derivatives have been identified in laboratory experiments simulating photoprocessing of ices under astrophysical conditions. Read More

Sci Rep 2018 Dec 17;8(1):17895. Epub 2018 Dec 17.

P.N. Lebedev Physical Institute of RAS, Moscow, Russian Federation.

Optical generation of compact magnetized plasma structures is studied in the moderate intensity domain. A sub-ns laser beam irradiated snail-shaped targets with the intensity of about 10 W/cm. With a neat optical diagnostics, a sub-megagauss magnetized plasmoid is traced inside the target. Read More

Eur Phys J C Part Fields 2018 27;78(10):866. Epub 2018 Oct 27.

6Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa, Edifício C8, Campo Grande, 1749-016 Lisbon Portugal.

We show that families of nonlinear gravity theories formulated in a metric-affine approach and coupled to a nonlinear theory of electrodynamics can be mapped into general relativity (GR) coupled to another nonlinear theory of electrodynamics. This allows to generate solutions of the former from those of the latter using purely algebraic transformations. This correspondence is explicitly illustrated with the Eddington-inspired Born-Infeld theory of gravity, for which we consider a family of nonlinear electrodynamics and show that, under the map, preserve their algebraic structure. Read More

Nat Commun 2018 11 30;9(1):5109. Epub 2018 Nov 30.

Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan.

Magnetic reconnections play essential roles in space, astrophysical, and laboratory plasmas, where the anti-parallel magnetic field components re-connect and the magnetic energy is converted to the plasma energy as Alfvénic out flows. Although the electron dynamics is considered to be essential, it is highly challenging to observe electron scale reconnections. Here we show the experimental results on an electron scale reconnection driven by the electron dynamics in laser-produced plasmas. Read More

Rev Sci Instrum 2018 Nov;89(11):114503

Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA.

This paper describes a novel electrostatic analyzer concept to measure suprathermal ions, a Double-Cusp Analyzer for SupraThermals (DCAST) that employs a double-shell cusp structure. Due to the necessity of measuring higher energy levels to cover the suprathermal range, existing ion instruments require greater size and mass. Moreover, observations of potentially low-flux suprathermal ions require a long integration time to fully characterize key ion properties in the plasmas (e. Read More

Rep Prog Phys 2019 01 21;82(1):016903. Epub 2018 Nov 21.

ARTEMIS, Université Côte d'Azur, Observatoire Côte d'Azur, CNRS, 06304 Nice, France. Physics and Astronomy, Carleton College, Northfield, MN 55057, United States of America.

A stochastic background of gravitational waves could be created by the superposition of a large number of independent sources. The physical processes occurring at the earliest moments of the universe certainly created a stochastic background that exists, at some level, today. This is analogous to the cosmic microwave background, which is an electromagnetic record of the early universe. Read More

Phys Chem Chem Phys 2019 Feb;21(7):3669-3675

Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland.

The rotational spectrum of monodeutero-oxirane was analysed as measured using the Zurich Gigahertz (GHz) spectrometer and our highest resolution Fourier Transform Infrared (FTIR) spectrometer system coupled to synchrotron radiation at the Swiss Light Source (SLS). 112 distinct line frequencies have been newly assigned in the GHz range (extended to 120 GHz, compared to previous work extending to only 59 GHz) including rotational states up to J = 23. We have furthermore assigned 398 lines in the far infrared or Terahertz range (0. Read More

Science 2018 12 15;362(6421):1391-1395. Epub 2018 Nov 15.

Institute for Space and Astronautical Sciences, Sagamihara, Japan.

Magnetic reconnection is an energy conversion process that occurs in many astrophysical contexts including Earth's magnetosphere, where the process can be investigated in situ by spacecraft. On 11 July 2017, the four Magnetospheric Multiscale spacecraft encountered a reconnection site in Earth's magnetotail, where reconnection involves symmetric inflow conditions. The electron-scale plasma measurements revealed (i) super-Alfvénic electron jets reaching 15,000 kilometers per second; (ii) electron meandering motion and acceleration by the electric field, producing multiple crescent-shaped structures in the velocity distributions; and (iii) the spatial dimensions of the electron diffusion region with an aspect ratio of 0. Read More

Astron Astrophys 2018 Oct 3;618. Epub 2018 Oct 3.

Instituto de Radioastronomía Milimétrica, Avenida Divina Pastora 7, E-18012, Granada, Spain.

This work presents a detailed analysis of the laboratory and astrophysical spectral data available for SiC, SiC,SiC, SiCC, and SiC. New data on the rotational lines of these species between 70 and 350 GHz have been obtained with high spectral resolution (195 kHz) with the IRAM 30m telescope in the direction of the circumstellar envelope IRC +10216. Frequency measurements can reach an accuracy of 50 kHz for features observed with a good signal to noise ratio. Read More