6,336 research outputs found
Oscillations of Ultralight Dark Photon into Gravitational Waves
The discovery of gravitational waves (GWs) opens a new window for exploring
the physics of the early universe. Identifying the source of GWs and their
spectra today turn out to be the important tasks so as to assist the
experimental detection of stochastic GWs. In this paper, we investigate the
oscillations of the ultralight dark photon (ULDP) into GWs in the dark halo.
Assuming dark matter is composed of the ULDP and there are primordial dark
magnetic fields (PDMFs) arising from the axion inflation and/or the dark phase
transition, then the ULDP can oscillate into the GW when it passes through an
environment of PDMFs. We derive the local energy density of GWs in the galaxy
cluster induced by the instaneous oscillation of ULDP in the PDMFs. These
stochastic local GWs exhibit a pulse-like spectrum, with frequency depending on
the mass of the ULDP, and can be detected in Pulsar Timing Arrays (PTAs) or
future space-based interferometers. We also find that the low-frequency GW
signal observed by the NANOGrav collaboration and other PTA experiments can be
explained by the oscillation of the ULDP in the PDMFs in the early universe.Comment: 7 pages, 3 figure
Poly[[bis(2,2-bipyridine)bis[μ6-5-(carboxylatomethoxy)benzene-1,3-dicarboxylato]trimanganese(II)] monohydrate]
The title compound, {[Mn3(C10H5O7)2(C10H8N2)2]·H2O}n, was synthesized under hydrothermal conditions. Six carboxylate groups of six 5-(carboxylatomethoxy)benzene-1,3-dicarboxylate anions (OABDC3−) join three MnII ions into a trinuclear centrosymmetric [Mn3(μ2-COO)6] unit with one Mn site situated on a centre of inversion. The latter MnII ion exhibits a distorted MnO6 coordination, whereas the other MnII ion has a trigonal–bipyramidal MnN2O3 coordination environment resulting from three carboxylate O atoms and the two N atoms of the bipyridine ligand. Adjacent units are linked to each other by OABDC3− ligands into a layer parallel to (010). Within the layer, O—H⋯O hydrogen-bonding interactions involving the uncoordinated and half-occupied water molecule and the free carboxylate O atoms are observed. The layers stack along [010], constructing a three-dimensional structure through π–π interactions between adjacent pyridine rings, with a centroid–centroid distance of 3.473 (5) Å
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