Search Our Scientific Publications & Authors

Nat Commun 2021 May 11;12(1):2690. Epub 2021 May 11.

Department of Chemistry, University of Hawaii, Honolulu, HI, USA.

The surface mineralogy of dwarf planet Ceres is rich in ammonium (NH) bearing phyllosilicates. However, the origin and formation mechanisms of ammoniated phyllosilicates on Ceres's surface are still elusive. Here we report on laboratory simulation experiments under astrophysical conditions mimicking Ceres' physical and chemical environments with the goal to better understand the source of ammoniated minerals on Ceres' surface. Read More

Nat Commun 2021 May 11;12(1):2679. Epub 2021 May 11.

LULI, CNRS, CEA, École Polytechnique, UPMC, Univ Paris 06: Sorbonne Universités, Institut Polytechnique de Paris, F-91128 Palaiseau cedex, France.

Turbulence is ubiquitous in the universe and in fluid dynamics. It influences a wide range of high energy density systems, from inertial confinement fusion to astrophysical-object evolution. Understanding this phenomenon is crucial, however, due to limitations in experimental and numerical methods in plasma systems, a complete description of the turbulent spectrum is still lacking. Read More

Phys Rev Lett 2021 Apr;126(16):162702

INFN Sezione di Catania, Via Santa Sofia 64, I-95123 Catania, Italy.

We investigate the possibility that the low mass companion of the black hole in the source of GW190814 was a strange quark star. This possibility is viable within the so-called two-families scenario in which neutron stars and strange quark stars coexist. Strange quark stars can reach the mass range indicated by GW190814, M∼(2. Read More

Phys Rev Lett 2021 Apr;126(16):161102

Dipartimento di Fisica "Enrico Fermi," Università di Pisa, Pisa I-56127, Italy.

Causality and the generalized laws of black hole thermodynamics imply a bound, known as the Bekenstein-Hod universal bound, on the information emission rate of a perturbed system. Using a time-domain ringdown analysis, we investigate whether remnant black holes produced by the coalescences observed by Advanced LIGO and Advanced Virgo obey this bound. We find that the bound is verified by the astrophysical black hole population with 94% probability, providing a first confirmation of the Bekenstein-Hod bound from black hole systems. Read More

Astrophys J Lett 2021 Feb 29;907(2). Epub 2021 Jan 29.

Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, USA.

Cluster analysis of presolar silicon carbide grains based on literature data for C/C, N/N, Si/Si, and Si/Si including or not inferred initial Al/Al data, reveals nine clusters agreeing with previously defined grain types but also highlighting new divisions. Mainstream grains reside in three clusters probably representing different parent star metallicities. One of these clusters has a compact core, with a narrow range of composition, pointing to an enhanced production of SiC grains in asymptotic giant branch (AGB) stars with a narrow range of masses and metallicities. Read More

Astrobiology 2021 May;21(5):526-540

Actinium Chemical Research Institute, Rome, Italy.

A selection of five proteinogenic amino acids-glycine, isoleucine, phenylalanine, tyrosine, and tryptophan-were studied in the mid-infrared and in the far-infrared with the purpose to facilitate the search and identification of these astrobiologically and astrochemically relevant molecules in space environments. The molar extinction coefficients (ɛ) of all mid- and far-infrared bands were determined as well as the integrated molar absorptivities (ψ). The mid-infrared spectra of the five selected amino acids were recorded also at three different temperatures from -180°C to ambient temperature to +200°C. Read More

Nature 2021 May 5;593(7857):47-50. Epub 2021 May 5.

Division of Particle and Astrophysical Science, Nagoya University, Nagoya, Japan.

Galaxy clusters are known to harbour magnetic fields, the nature of which remains unresolved. Intra-cluster magnetic fields can be observed at the density contact discontinuity formed by cool and dense plasma running into hot ambient plasma, and the discontinuity exists near the second-brightest galaxy, MRC 0600-399, in the merging galaxy cluster Abell 3376 (redshift 0.0461). Read More

Entropy (Basel) 2021 Apr 29;23(5). Epub 2021 Apr 29.

Center for Nonlinear Science, University of North Texas, Denton, TX 76203-5017, USA.

We study the emission of photons from germinating seeds using an experimental technique designed to detect light of extremely small intensity. We analyze the dark count signal without germinating seeds as well as the photon emission during the germination process. The technique of analysis adopted here, called diffusion entropy analysis (DEA) and originally designed to measure the temporal complexity of astrophysical, sociological and physiological processes, rests on Kolmogorov complexity. Read More

Phys Rev Lett 2021 Apr;126(15):151301

Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA.

We place constraints on the normalized energy density in gravitational waves from first-order strong phase transitions using data from Advanced LIGO and Virgo's first, second, and third observing runs. First, adopting a broken power law model, we place 95% confidence level upper limits simultaneously on the gravitational-wave energy density at 25 Hz from unresolved compact binary mergers, Ω_{CBC}<6.1×10^{-9}, and strong first-order phase transitions, Ω_{BPL}<4. Read More

Phys Rev Lett 2021 Apr;126(15):151101

Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA.

We study smooth bubble spacetimes in five-dimensional Einstein-Maxwell theory that resemble four-dimensional magnetic black holes upon Kaluza-Klein reduction. We denote them as topological stars since they have topological cycles supported by magnetic flux. They can be macroscopically large compared to the size of the Kaluza-Klein circle and could describe qualitative properties of microstate geometries for astrophysical black holes. Read More

Proc Biol Sci 2021 Apr 28;288(1949):20202332. Epub 2021 Apr 28.

Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06511, USA.

To make sense of our present biodiversity crises, the modern rate of species extinctions is commonly compared to a benchmark, or 'background,' rate derived from the fossil record. These estimates are critical for bounding the scale of modern diversity loss, but are yet to fully account for the fundamental structure of extinction rates through time. Namely, a substantial fraction of extinctions within the fossil record occurs within relatively short-lived extinction pulses, and not during intervals characterized by background rates of extinction. Read More

Astrobiology 2021 Apr 27. Epub 2021 Apr 27.

Division of Epidemiology, The New York State Psychiatric Institute at Columbia University, New York Psychiatric Institute, New York, USA.

In this article, we partially quantify the biological potential of an exoplanet. We employ a variety of biogeographical analyses, placing biological evolution in the context of the geological evolution of the planet as a whole. Terrestrial (as in Earthly) biodiversity is tightly constrained in terms of species richness by its environment. Read More

Phys Rev Lett 2021 Apr;126(14):141301

Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.

We present the first joint analysis of cluster abundances and auto or cross-correlations of three cosmic tracer fields: galaxy density, weak gravitational lensing shear, and cluster density split by optical richness. From a joint analysis (4×2pt+N) of cluster abundances, three cluster cross-correlations, and the auto correlations of the galaxy density measured from the first year data of the Dark Energy Survey, we obtain Ω_{m}=0.305_{-0. Read More

Phys Chem Chem Phys 2021 Apr;23(15):9235-9248

Department of Chemistry, University of Colorado, Boulder, CO 80309-215, USA.

A recent experiment at the Dalian Coherent Light Source (DCLS) has provided measurements of the partial cross sections for the photodissociation of water vapor over an unprecedented range of wavelengths in the vacuum ultraviolet (VUV) region. It was found that the three body dissociation channel, H + H + O(3P/1D), becomes prominent at wavelengths shorter than the Lyman α-line at 121.6 nm. Read More

Phys Chem Chem Phys 2021 Apr;23(15):9571-9584

School of Physics and Physical Engineering, Qufu Normal University, 273165 Qufu, China and Department of Physics, Universidade Federal do Espírito Santo, 29075-910 Vitória, Brazil and Department of Chemistry, and Chemistry Centre, University of Coimbra, 3004-535 Coimbra, Portugal.

Cost-effectiveness and accuracy are two basic pillars in electronic structure calculations. While cost-effectiveness enhances applicability, high accuracy is sustained when employing advanced computational tools. With the gold standard method of ab initio quantum chemistry at the focal point, canonical CCSD(T) and modern explicitly correlated CCSD(T)-F12 calculations are employed hand in hand to develop accurate hybrid post-CBS extrapolation schemes, which are validated using popular training sets involving a total of 130 molecules. Read More

Nature 2021 Apr 21;592(7855):537-540. Epub 2021 Apr 21.

Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, USA.

Recent multi-dimensional simulations suggest that high-entropy buoyant plumes help massive stars to explode. Outwardly protruding iron (Fe)-rich fingers of gas in the galactic supernova remnant Cassiopeia A seem to match this picture. Detecting the signatures of specific elements synthesized in the high-entropy nuclear burning regime (that is, α-rich freeze out) would constitute strong substantiating evidence. Read More

Phys Rev E 2021 Mar;103(3-1):033106

School of Mathematical Sciences, Tel Aviv University, Tel Aviv 69978, Israel.

The nature of thermonuclear explosions of white-dwarf stars is a fundamental astrophysical issue, the first principle interpretation of which is still commonly regarded as an unresolved problem. There is a general consensus that stellar explosions are a manifestation of the deflagration-to-detonation transition of an outward propagating self-accelerating thermonuclear flame subjected to instability-induced corrugations. A similar problem arises in unconfined terrestrial flames where a positive feedback mechanism leading to the pressure runaway has been identified. Read More

Phys Rev Lett 2021 Apr;126(13):131102

Centro Brasileiro de Pesquisas Físicas (CBPF), Rio de Janeiro, CEP 22290-180, Brazil.

The open question of whether a black hole can become tidally deformed by an external gravitational field has profound implications for fundamental physics, astrophysics, and gravitational-wave astronomy. Love tensors characterize the tidal deformability of compact objects such as astrophysical (Kerr) black holes under an external static tidal field. We prove that all Love tensors vanish identically for a Kerr black hole in the nonspinning limit or for an axisymmetric tidal perturbation. Read More

Front Astron Space Sci 2021 Mar 25;8. Epub 2021 Mar 25.

IRAP, Université de Toulouse, CNRS, UPS, CNES, TOULOUSE, France.

Laboratory experiments are essential in exploring the mechanisms involved in stardust formation. One key question is how a metal is incorporated into dust for an environment rich in elements involved in stardust formation (C, H, O, Si). To address experimentally this question we have used a radiofrequency cold plasma reactor in which cyclic organosilicon dust formation is observed. Read More

Astron Astrophys 2021 Jan 15;645. Epub 2021 Jan 15.

Instituto de Física Fundamental (IFF-CSIC). Group of Molecular Astrophysics, C/Serrano 123, 28006 Madrid, Spain.

Context: At least a dozen molecules with a formyl group (HCO) have been observed to date in the interstellar medium (ISM), suggesting that other such species exist and remain to be discovered. However, there is still a lack of high-resolution spectroscopic data for simple molecular species of this type that could provide a basis for their detection.

Aims: Cyclopropanecarboxaldehyde, c-CHCHO, is a small molecule containing a formyl group and is therefore an interesting candidate for astrophysical detection. Read More

Rev Sci Instrum 2021 Mar;92(3):033525

Electrical and Computer Engineering Department, Colorado State University, Fort Collins, Colorado 80523, USA.

Fine-structure x-ray spectra have been measured from foils with embedded tracer layers at two laser facilities. A suite of layered foils with thin Ti tracers under varied tamper layers was studied at both the Titan and the ALEPH 400 nm laser facilities, where Ti Heα emission was recorded using a high-resolution Bragg crystal spectrometer. Several indicators of plasma parameters are examined in the spectra, including temperature- and density-dependent line ratios and line broadening from Stark and opacity effects. Read More

Rev Sci Instrum 2021 Mar;92(3):035111

NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, Maryland 20771, USA.

Measuring the faint polarization signal of the cosmic microwave background (CMB) not only requires high optical throughput and instrument sensitivity but also control over systematic effects. Polarimetric cameras or receivers used in this setting often employ dielectric vacuum windows, filters, or lenses to appropriately prepare light for detection by cooled sensor arrays. These elements in the optical chain are typically designed to minimize reflective losses and hence improve sensitivity while minimizing potential imaging artifacts such as glint and ghosting. Read More

Entropy (Basel) 2021 Mar 31;23(4). Epub 2021 Mar 31.

Rosseland Centre for Solar Physics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo, Norway.

The solar photosphere and the outer layer of the Sun's interior are characterized by convective motions, which display a chaotic and turbulent character. In this work, we evaluated the pseudo-Lyapunov exponents of the overshooting convective motions observed on the Sun's surface by using a method employed in the literature to estimate those exponents, as well as another technique deduced from their definition. We analyzed observations taken with state-of-the-art instruments at ground- and space-based telescopes, and we particularly benefited from the spectro-polarimetric data acquired with the Interferometric Bidimensional Spectrometer, the Crisp Imaging SpectroPolarimeter, and the Helioseismic and Magnetic Imager. Read More

Phys Rev Lett 2021 Mar;126(10):101101

Stockholm University and The Oskar Klein Centre for Cosmoparticle Physics, Alba Nova, 10691 Stockholm, Sweden.

Recent observations by the Alpha Magnetic Spectrometer (AMS-02) have tentatively detected a handful of cosmic-ray antihelium events. Such events have long been considered as smoking-gun evidence for new physics, because astrophysical antihelium production is expected to be negligible. However, the dark-matter-induced antihelium flux is also expected to fall below current sensitivities, particularly in light of existing antiproton constraints. Read More

J Phys Chem A 2021 Apr 30;125(13):2764-2769. Epub 2021 Mar 30.

Institut des Sciences Moléculaires d'Orsay, CNRS, Université Paris-Saclay, 91405, Orsay, France.

The NH radical is a key component in many astrophysical environments, both in its neutral and cationic forms, being involved in the formation of complex N-bearing species. To gain insight into the photochemical processes into which it operates and to model accurately the ensuing chemical networks, the knowledge of its photoionization efficiency is required, but no quantitative determination has been carried out so far. Combining a flow-tube H-abstraction radical source, a double imaging photoelectron-photoion spectrometer, and a vacuum-ultraviolet synchrotron excitation, the absolute photoionization cross section of the amino radical has been measured in the present work for the first time at two photon energies: σ(12. Read More

Rep Prog Phys 2021 Mar 25. Epub 2021 Mar 25.

Michigan State University National Superconducting Cyclotron Laboratory, East Lansing, Michigan, UNITED STATES.

Electron captures on nuclei play an essential role for the dynamics of several astrophysical objects, including core-collapse and thermonuclear supernovae, the crust of accreting neutron stars in binary systems and the final core evolution of intermediate mass stars. In these astrophysical objects, the capture occurs at finite temperatures and at densities at which the electrons form a degenerate relativistic electron gas. The capture rates can be derived in perturbation theory where allowed nuclear transitions (Gamow-Teller transitions) dominate, except at the higher temperatures achieved in core-collapse supernovae where forbidden transitions also contribute significantly to the rates. Read More

Phys Rev Lett 2021 Mar;126(9):091601

CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China.

We explore a novel detection possibility for solar axions, which relies only on their couplings to nucleons, via the axion-induced dissociation of deuterons into their constituent neutrons and protons. An opportune target for this process is the now-concluded Sudbury Neutrino Observatory (SNO) experiment, which relied upon large quantities of heavy water to resolve the solar neutrino problem. From the full SNO dataset we exclude in a model-independent fashion isovector axion-nucleon couplings |g_{aN}^{3}|≡1/2|g_{an}-g_{ap}|>2×10^{-5}  GeV^{-1} at 95% C. Read More

Phys Rev Lett 2021 Mar;126(9):091301

Institute for Astroparticle Physics, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.

We report on a search for nuclear recoil signals from solar ^{8}B neutrinos elastically scattering off xenon nuclei in XENON1T data, lowering the energy threshold from 2.6 to 1.6  keV. Read More

Phys Rev Lett 2021 Mar;126(9):095101

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

Collisionless shocks are ubiquitous in the Universe and often associated with a strong magnetic field. Here, we use large-scale particle-in-cell simulations of nonrelativistic perpendicular shocks in the high-Mach-number regime to study the amplification of the magnetic field within shocks. The magnetic field is amplified at the shock transition due to the ion-ion two-stream Weibel instability. Read More

Phys Rev Lett 2021 Mar;126(9):091101

Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, Illinois 60510, USA.

We perform a comprehensive study of Milky Way (MW) satellite galaxies to constrain the fundamental properties of dark matter (DM). This analysis fully incorporates inhomogeneities in the spatial distribution and detectability of MW satellites and marginalizes over uncertainties in the mapping between galaxies and DM halos, the properties of the MW system, and the disruption of subhalos by the MW disk. Our results are consistent with the cold, collisionless DM paradigm and yield the strongest cosmological constraints to date on particle models of warm, interacting, and fuzzy dark matter. Read More