3,362 research outputs found
Matching of analytical and numerical solutions for neutron stars of arbitrary rotation
We demonstrate the results of an attempt to match the two-soliton analytical
solution with the numerically produced solutions of the Einstein field
equations, that describe the spacetime exterior of rotating neutron stars, for
arbitrary rotation. The matching procedure is performed by equating the first
four multipole moments of the analytical solution to the multipole moments of
the numerical one. We then argue that in order to check the effectiveness of
the matching of the analytical with the numerical solution we should compare
the metric components, the radius of the innermost stable circular orbit
(), the rotation frequency and the
epicyclic frequencies . Finally we present some
results of the comparison.Comment: Contribution at the 13th Conference on Recent Developments in Gravity
(NEB XIII), corrected typo in of eq. 5 of the published versio
An ecohydrological journey of 4500 years reveals a stable but threatened precipitationâgroundwater recharge relation around Jerusalem
Groundwater is a key water resource in semiarid and seasonally dry regions around the world, which is replenished
by intermittent precipitation events and mediated by vegetation, soil, and regolith properties. Here, a climate
reconstruction of 4500 years for the Jerusalem region was used to determine the relation between climate, vegetation,
and groundwater recharge. Despite changes in air temperature and vegetation characteristics, simulated recharge
remained linearly related to precipitation over the entire analyzed period, with drier decades having lower rates
of recharge for a given annual precipitation due to soil memory effects. We show that in recent decades, the lack of
changes in the precipitationâgroundwater recharge relation results from the compensating responses of vegetation
to increasing CO2, i.e., increased leaf area and reduced stomatal conductance. This multicentury relation is
expected to be modified by climate change, with changes up to â20% in recharge for unchanged precipitation,
potentially jeopardizing water resource availability
Editorial: Ecosystem Services and Disservices Provided by Plant-Feeding Predatory Arthropods
Editorial of the Research Topic issue on Ecosystem Services and Disservices Provided by Plant-Feeding Predatory Arthropod
Analytical approximation of the exterior gravitational field of rotating neutron stars
It is known that B\"acklund transformations can be used to generate
stationary axisymmetric solutions of Einstein's vacuum field equations with any
number of constants. We will use this class of exact solutions to describe the
exterior vacuum region of numerically calculated neutron stars. Therefore we
study how an Ernst potential given on the rotation axis and containing an
arbitrary number of constants can be used to determine the metric everywhere.
Then we review two methods to determine those constants from a numerically
calculated solution. Finally, we compare the metric and physical properties of
our analytic solution with the numerical data and find excellent agreement even
for a small number of parameters.Comment: 9 pages, 10 figures, 3 table
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