13,687 research outputs found
A Dark Matter Signature for Condensed Neutrinos
We derive the signature for condensed neutrino objects (CNOs) as the primary
source of Dark Matter. Restricting our source data to minimize systematic
errors, we find that by just using weak lensing data and Sunyaev-Zel'dovich
data, that there may be a weak CNO signature.Comment: 21 pages, 5 figures. Accepted for publication in the International
Journal of Modern Physics D (IJMPD
Electromagnetic Pulse from Final Gravitational Stellar Collapse
We employ an effective gravitational stellar final collapse model which
contains the relevant physics involved in this complex phenomena: spherical
radical infall in the Schwarzschild metric of the homogeneous core of an
advanced star, giant magnetic dipole moment, magnetohydrodynamic material
response and realistic equations of state (EOS). The electromagnetic pulse is
computed both for medium size cores undergoing hydrodynamic bounce and large
size cores undergoing black hole formation. We clearly show that there must
exist two classes of neutron stars, separated by maximum allowable masses:
those that collapsed as solitary stars (dynamical mass limit) and those that
collapsed in binary systems allowing mass accretion (static neutron star mass).
Our results show that the electromagnetic pulse spectrum associated with black
hole formation is a universal signature, independent of the nuclear EOS. Our
results also predict that there must exist black holes whose masses are less
than the static neutron star stability limit.Comment: 9 pages, 8 figures, to be published in Astronomy and Astrophysic
Platelet Collapse Model of Pulsar Glitches
A platelet collapse model of starquakes is introduced. It displays
self-organized criticality with a robust power-law behavior. The simulations
indicate a near-constant exponent, whenever scaling is present.Comment: Figures available by sending request to Ivan Schmidt:
[email protected]
Epitaxial strain and the magnetic properties of canted antiferromagnetic perovskite NaNiF3 thin films
The perovskite crystal structure is known to exhibit a multitude of interesting physical phenomena owing to the intricate coupling of the electronic and magnetic properties to the structure. Fluoroperovskites offer an alternative chemistry to the much more widely studied oxide materials, which may prove advantageous for applications. It is demonstrated here for the first time that the antiferromagnetic perovskite fluoride, NaNiF3, can be synthesized in thin film form. The films were grown via molecular beam epitaxy on SrTiO3 (100) substrates to produce high quality epitaxial films in the thickness range of 5-50 nm. The Pnma structure of the films was confirmed by x-ray diffraction. There was a decrease in the out-of-plane lattice spacing from the bulk value corresponding to a maximum strain of 1.7% in the thinnest film. Canted antiferromagnetism was measured in all films using magnetometry and a negative change in the antiferromagnetic ordering temperature of ΔTN = - 9.1 ± 0.7 K was observed with increasing strain
Searching for Extra Dimensions in the Early Universe
We investigate extra spatial dimensions () in the early
universe using very high resolution molecular rotational spectroscopic data
derived from a large molecular cloud containing moderately cold carbon monoxide
gas at Z . It turns out that the -dependent quantum
mechanical wavelength transitions are solvable for a linear molecule and we
present the solution here. The CO microwave data allows a very precise
determination of . The probability
that is one in 7794, only 850 million years (using the
standard cosmology) after the Big Bang.Comment: 17 pages, 2 figure
Eigenvalues of the Laplacian of a graph
Let G be a finite undirected graph with no loops or multiple edges. The Laplacian matrix of G, Delta(G), is defined by Delta sub ii = degree of vertex i and Delta sub ij = -1 if there is an edge between vertex i and vertex j. The structure of the graph G is related to the eigenvalues of Delta(G); in particular, it is proved that all the eigenvalues of Delta(G) are nonnegative, less than or equal to the number of vertices, and less than or equal to twice the maximum vertex degree. Precise conditions for equality are given
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