Results 11 to 20 of about 395,351 (376)
A Brief Review on Primordial Black Holes as Dark Matter
Frontiers in Astronomy and Space Sciences, 2021 Primordial black holes (PBHs) represent a natural candidate for one of the components of the dark matter (DM) in the Universe. In this review, we shall discuss the basics of their formation, abundance and signatures.
Pablo Villanueva-Domingo +2 more
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Accretion Rates and the Accretion Efficiency in AGNs [PDF]
Publications of the Astronomical Society of Japan, 2003 Abstract We used the standard geometrical-thin accretion theory to obtain the accretion rates in Seyfert 1 galaxies and quasars. Combining the accretion rates with the bolometric luminosity, we obtained the accretion efficiency. We found that most Seyfert 1 galaxies and radio-quiet quasars have lower accretion efficiencies, while most ...
Yong-Heng Zhao +2 more
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Formation of planetary systems by pebble accretion and migration [PDF]
Astronomy & Astrophysics, 2018 At least 30% of main sequence stars host planets with sizes of between 1 and 4 Earth radii and orbital periods of less than 100 days. We use N-body simulations including a model for gas-assisted pebble accretion and disk–planet tidal interaction to study
B. Bitsch +6 more
semanticscholar +1 more source
Journal of Marine Science and Engineering, 2021 Persistence of tidal wetlands under conditions of sea level rise depends on vertical accretion of organic and inorganic matter, which vary in their relative abundance across estuarine gradients.
Jenny R. Allen +2 more
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Stochastic accretion of the Earth
Nature Astronomy, 2022 The Earth is depleted in volatile elements relative to chondritic meteorites, its possible building blocks. Abundances of volatile elements descend roughly log-linearly with their calculated volatilities during solar nebula condensation [1, 2]. This depletion, however, is not accompanied by any stable isotope fractionation, which would otherwise be ...
Paolo Sossi +4 more
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Totally Accretive Operators [PDF]
Proceedings of the American Mathematical Society, 1988 Let A A be a (possibly unbounded) linear operator on a Banach space. We show that, when A A generates a uniformly bounded strongly continuous semigroup { e − t
Ralph deLaubenfels
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2200 million years of crustal evolution: The Baltic Shield [PDF]
Bulletin of the Geological Society of Finland, 1986 The crustal history of the Baltic shield is interpreted in the light of the plate tectonic concept. Five tectonic cycles, each characterized by special lithological and structural features, are distinguished: The Early Archean (> 2900 Ma), the Late ...
G. Gaál
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Tectonic models for accretion of the Central Asian Orogenic Belt
Journal of the Geological Society, 2007 The Central Asian Orogenic Belt (c. 1000–250 Ma) formed by accretion of island arcs, ophiolites, oceanic islands, seamounts, accretionary wedges, oceanic plateaux and microcontinents in a manner comparable with that of circum-Pacific Mesozoic–Cenozoic ...
B. Windley +4 more
semanticscholar +1 more source
Hot Accretion Flows Around Black Holes [PDF]
, 2014 Black hole accretion flows can be divided into two broad classes: cold and hot. Whereas cold accretion flows consist of cool optically thick gas and are found at relatively high mass accretion rates, hot accretion flows, the topic of this review, are ...
F. Yuan, R. Narayan
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Accretion Dynamics on Wet Granular Materials. [PDF]
Physical Review Letters, 2017 Wet granular aggregates are common precursors of construction materials, food, and health care products. The physical mechanisms involved in the mixing of dry grains with a wet substrate are not well understood and difficult to control.
G. Saingier, A. Sauret, P. Jop
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