81 research outputs found
N-body model of black holes with quantum dust cores
Gravitational collapses are natural laboratories where observable signatures of a quantum theory
of gravity may be produced and may be hidden in detectable astrophysical phenomena. A rooted
theoretical description of a spherically symmetric gravitational collapse in General Relativity
is given by the Oppenheimer-Snyder model. However, General Relativity is expected to break
down at the very late stages of the collapse, and the classical dynamics to be affected by
quantum gravitational effects. An effective quantum description of the Oppenheimer-Snyder
model is provided by means of a bound-state quantisation procedure, where the areal radius
of a single layer of dust is quantised in analogy to the position of the electron in the hydrogen
atom [1]. In this work, the same procedure has been extended to an isotropic distribution of
dust, which is discretised into an arbitrary number N of nested layers, each containing νi dust
particles. The final state of the collapsed matter is represented by the global ground state of a
core of quantum dust of average areal radius Rs ≈ 3/2GNM, where M is the total ADM mass,
which naturally reproduces the area quantisation of a black hole. Then, macroscopic properties
of the core have been investigated assuming that a fraction of dust particles is in an arbitrary
excited state. Furthermore, a more accurate description of the ground state dust distribution
has been explicitly determined. Near the centre, the mass function is shown to grow linearly
with the areal radius, and the central singularity is replaced by an integrable singularity. The
core surface is instead described by a non-linear fifth-order polynomial in the transitional shell
16/9 RH ≲ r ≲ 3/4 RH and matches smoothly the outer Schwarzschild solution and the inner
bulk matter. Finally, observational signatures of quantum gravitational effects provided by this
model has been addressed
3-Methyl-1,4-dioxo-1,4-dihydronaphthalen-2-yl 4-aminobenzoate
The crystal structure of the title compound, C18H13NO4, the oxidized form of the drug aminaftone used in venous disease therapy, is characterized by the presence of ribbons of hydrogen-bonded molecules parallel to the [111] crystallographic direction and by stacking interactions between rings [centroid–centroid distance between quinone rings = 3.684 (3) Å and between aminobenzoate rings = 4.157 (3) Å] along the ribbons
Diisopropyl{2-[2-(2-oxopyrrolidin-1-yl)acetamido]ethyl}ammonium hydrogen sulfate
The structure of the title compound, C14H28N3O2
+·HSO4
−, a nootropic drug (pramiracetam) investigated for cognition-enhancing properties, is closely similar to that of the previously determined acetonitrile solvate, both structures being characterized by the presence of ribbons of hydrogen-bonded ions. The pyrrolidine ring adopts an envelope conformation
Collision dissociation study of negative ion chemical ionization (OH−) fragments of bornyl C4C5 esters
Negative ion chemical ionization and collisional activation mass spectrometry of naturally occurring bornyl C4C5 esters
ChemInform Abstract: Convenient Ruthenium-Complex Catalyzed Synthesis of Enterolactone from the Corresponding Dibenzylidene Succinic Acid Moiety.
Electron impact mass spectra of naturally occurring bornyl, 4-terpinenyl and α- terpinyl C3—C5 esters
Radical processes in remote charge fragmentations of lithium-cationized long-chain alkenyl and alkadienyl salicylic acids
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