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Radiat Environ Biophys 2021 Jun 23. Epub 2021 Jun 23.

Institute of Biochemistry and Microbiology, Austral University of Chile, Valdivia, Chile.

Ionizing radiation of astrophysical origin might have played an important role in biological evolution during the long course of Earth's evolution. Several phenomena might have induced intense fluctuations in background ionizing radiation, such as highly energetic stellar explosions. There might also be anthropogenic causes for environmental radiation fluctuations, resulting from nuclear industry activities. Read More

Nat Commun 2021 Jun 22;12(1):3839. Epub 2021 Jun 22.

Department of Physics, American University of Sharjah, Sharjah, UAE.

Regarded as the most important ion in interstellar chemistry, the trihydrogen cation, [Formula: see text], plays a vital role in the formation of water and many complex organic molecules believed to be responsible for life in our universe. Apart from traditional plasma discharges, recent laboratory studies have focused on forming the trihydrogen cation from large organic molecules during their interactions with intense radiation and charged particles. In contrast, we present results on forming [Formula: see text] from bimolecular reactions that involve only an inorganic molecule, namely water, without the presence of any organic molecules to facilitate its formation. Read More

J Phys Chem Lett 2021 Jun 17;12(24):5789-5795. Epub 2021 Jun 17.

Institute of Modern Physics, Key Laboratory of Nuclear Physics and Ion-Beam Application (MOE), Fudan University, Shanghai 200433, China.

Hydrogen- or proton-migration-induced isomerization has recently been of concern for its critical role in the dissociation of organic molecules of astrophysical or biological relevance. Herein we present a combined experimental and theoretical study of the two-body C-C bond breakdown dissociation of ethane dication. For the asymmetric fragmentation channel CH + CH, the kinetic energy release measurements and quantum chemical calculations demonstrate that the reaction pathway involving hydrogen-migration-induced isomerization of [CH-CH] to [CH-CH] can be accessed the lowest triplet state rather than the ground singlet state of ethane dication. Read More

Phys Chem Chem Phys 2021 Jun;23(24):13672-13679

Universidade de São Paulo, Instituto de Química, Departamento de Química Fundamental, Av. Prof. Lineu Prestes, 748, São Paulo, São Paulo, 05508-000, Brazil.

Accurate potential energy curves were constructed for a manifold of electronic states of the hydroxyl dication using a highly correlated electronic structure approach (SA-CASSCF/MRCI+Q/aug-cc-pV5Z). The existence of a bound (meta)stable ground state and bound low-lying states for OH2+ are ruled out, but do not exclude the possibility of its transient formation and dissociation along the repulsive ground state potential energy curve. Our results do not support the conclusion reported for the observation of OH2+ by electron ionization from ground state OH+. Read More

Nat Commun 2021 Jun 11;12(1):3553. Epub 2021 Jun 11.

Météorage, Pau, France.

Lightning superbolts are the most powerful and rare lightning events with intense optical emission, first identified from space. Superbolt events occurred in 2010-2018 could be localized by extracting the high energy tail of the lightning stroke signals measured by the very low frequency ground stations of the World-Wide Lightning Location Network. Here, we report electromagnetic observations of superbolts from space using Van Allen Probes satellite measurements, and ground measurements, and with two events measured both from ground and space. Read More

Phys Rev Lett 2021 May;126(21):215101

SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.

Magnetic field amplification by relativistic streaming plasma instabilities is central to a wide variety of high-energy astrophysical environments as well as to laboratory scenarios associated with intense lasers and electron beams. We report on a new secondary nonlinear instability that arises for relativistic dilute electron beams after the saturation of the linear Weibel instability. This instability grows due to the transverse magnetic pressure associated with the beam current filaments, which cannot be quickly neutralized due to the inertia of background ions. Read More

Science 2021 06;372(6546)

Laser Interferometer Gravitational-Wave Observatory Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

Gravitational waves are ripples in spacetime generated by the acceleration of astrophysical objects; a direct consequence of general relativity, they were first directly observed in 2015. Here, I review the first 5 years of gravitational-wave detections. More than 50 gravitational-wave events have been found, emitted by pairs of merging compact objects such as neutron stars and black holes. Read More

Nat Commun 2021 May 28;12(1):3240. Epub 2021 May 28.

Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.

Turbulent radiation flow is commonplace in systems with strong, incoherent, light-matter interactions. In astrophysical contexts, photon bubble turbulence is considered a key mechanism behind enhanced radiation transport, and its importance has been widely asserted for a variety of high energy objects such as accretion disks and massive stars. Here, we show that analogous conditions to those of dense astrophysical objects can be obtained in large clouds of cold atoms, prepared in a laser-cooling experiment, driven close to a sharp electronic resonance. Read More

Phys Rev Lett 2021 May;126(19):191101

DESY, Platanenallee 6, 15738 Zeuthen, Germany.

We demonstrate that a population of active galactic nuclei (AGN) can describe the observed spectrum of ultra-high-energy cosmic rays (UHECRs) at and above the ankle, and that the dominant contribution comes from low-luminosity BL Lacertae objects. An additional, subdominant contribution from high-luminosity AGN is needed to improve the description of the composition observables, leading to a substantial neutrino flux that peaks at exaelectronvolt (EeV) energies. We also find that different properties for the low- and high-luminosity AGN populations are required; a possibly similar baryonic loading can already be excluded from current IceCube Neutrino Observatory observations. Read More

Phys Rev Lett 2021 May;126(19):191102

Fakultät für Physik, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany.

We establish strong gravitational lens systems as robust probes of axionlike particles (ALPs)-a candidate for dark matter. A tiny interaction of photons with ALPs induces birefringence. Multiple images of gravitationally lensed polarized objects allow measurement of differential birefringence, alleviating systematics and astrophysical dependencies. Read More

Phys Rev Lett 2021 May;126(19):191803

Illinois Center for Advanced Studies of the Universe and Department of Physics, University of Illinois, 1110 West Green Street, Urbana, Illinois 61801, USA.

Since decoupling in the early Universe in helicity states, primordial neutrinos propagating in astrophysical magnetic fields precess and undergo helicity changes. In view of various experimental bounds allowing a large magnetic moment of neutrinos, we estimate the helicity flipping for relic neutrinos in both cosmic and galactic magnetic fields. The flipping probability is sensitive both to the neutrino magnetic moment and the structure of the magnetic fields and is a potential probe of the fields. Read More

Front Chem 2021 11;9:664693. Epub 2021 May 11.

Department of Atomic, Molecular and Surface Processes (PAMS), Institute of Fundamental Physics (IFF-CSIC), CSIC, Madrid, Spain.

Theoretical-computational studies together with recent astronomical observations have shown that under extreme conditions in the interstellar medium (ISM), complexes of noble gases may be formed. Such observations have generated a wide range of possibilities. In order to identify new species containing such atoms, the present study gathers spectroscopic data for noble gas hydride cations, NgH (Ng = He, Ne, Ar) from high-level quantum chemistry computations, aiming to contribute in understanding the chemical bonding and electron sharing in these systems. Read More

Front Oncol 2021 11;11:634818. Epub 2021 May 11.

Department of Specialistic Clinical and Odontostomatological Sciences, Polytechnic University of Marche, Ancona, Italy.

Adopting three physically-motivated scales ("micro" - "meso" - "macro", which refer to mpc - kpc - Mpc, respectively) is paramount for achieving a unified theory of multiphase active galactic nuclei feeding and feedback, and it represents a keystone for astrophysical simulations and observations in the upcoming years. In order to promote this multi-scale idea, we have decided to adopt an interdisciplinary approach, exploring the possible conceptual similarities between supermassive black hole feeding and feedback cycles and the dynamics occurring in human cancer microenvironment. Read More

Phys Rev Lett 2021 May;126(18):181101

Department of Physics and Illinois Center for Advanced Studies of the Universe, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.

The Neutron Star Interior Composition Explorer (NICER) recently measured the mass and equatorial radius of the isolated neutron star PSR J0030+0451. We use these measurements to infer the moment of inertia, the quadrupole moment, and the surface eccentricity of an isolated neutron star for the first time, using relations between these quantities that are insensitive to the unknown equation of state of supranuclear matter. We also use these results to forecast the moment of inertia of neutron star A in the double pulsar binary J0737-3039, a quantity anticipated to be directly measured in the coming decade with radio observations. Read More

Rep Prog Phys 2021 Jun 17;84(7). Epub 2021 Jun 17.

Physics Department, Arizona State University, Tempe, AZ 85287, United States of America.

A variety of observations impose upper limits at the nano Gauss level on magnetic fields that are coherent on inter-galactic scales while blazar observations indicate a lower bound ∼10G. Such magnetic fields can play an important astrophysical role, for example at cosmic recombination and during structure formation, and also provide crucial information for particle physics in the early Universe. Magnetic fields with significant energy density could have been produced at the electroweak phase transition. Read More

An Acad Bras Cienc 2021 17;93(suppl 1):e20200801. Epub 2021 May 17.

Institute of Astronomy of the Russian Academy of Sciences, 48 Pyatnitskaya st. 119017, Moscow, Russia.

In the paper a scenario of an electromagnetic response formation from the merging of two black holes is considered. In this scenario it's assumed that the binary black hole is surrounded by an accretion disk. As a result of the black holes merging and mass loss, the accretion disk experiences a disturbance, which is accompanied by shock waves propagation of sufficiently high intensity. Read More

Phys Rev E 2021 Apr;103(4-1):043203

Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA.

Magnetohydrodynamic (MHD) turbulence affects both terrestrial and astrophysical plasmas. The properties of magnetized turbulence must be better understood to more accurately characterize these systems. This work presents ideal MHD simulations of the compressible Taylor-Green vortex under a range of initial subsonic Mach numbers and magnetic field strengths. Read More

Phys Rev Lett 2021 Apr;126(17):171101

Department of Physics, University of California, Santa Cruz, California 95064, USA.

Light, asteroid-mass primordial black holes, with lifetimes in the range between hundreds to several millions times the age of the Universe, are well-motivated candidates for the cosmological dark matter. Using archival COMPTEL data, we improve over current constraints on the allowed parameter space of primordial black holes as dark matter by studying their evaporation to soft gamma rays in nearby astrophysical structures. We point out that a new generation of proposed MeV gamma-ray telescopes will offer the unique opportunity to directly detect Hawking evaporation from observations of nearby dark matter dense regions and to constrain, or discover, the primordial black hole dark matter. Read More

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 05;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 04 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