1,042 research outputs found
First upper limit analysis and results from LIGO science data: stochastic background
I describe analysis of correlations in the outputs of the three LIGO
interferometers from LIGO's first science run, held over 17 days in August and
September of 2002, and the resulting upper limit set on a stochastic background
of gravitational waves. By searching for cross-correlations between the LIGO
detectors in Livingston, LA and Hanford, WA, we are able to set a 90%
confidence level upper limit of h_{100}^2 Omega_0 < 23 +/- 4.6.Comment: 7 pages; 1 eps figures; proceeding from 2003 Edoardo Amaldi Meeting
on Gravitational Wave
Recommended from our members
A mechanism for dust-induced destabilization of glacial climates
Abrupt transitions between cold/dry stadial and warm/wet interstadial states occurred during glacial periods in the absence of any known external forcing. The climate record preserved in polar glaciers, mountain glaciers, and widespread cave deposits reveals that these events were global in extent with temporal distribution implying an underlying memoryless process with millennial time scale. Here a theory is advanced implicating feedback between atmospheric dust and the hydrological cycle in producing these abrupt transitions. Calculations are performed using a radiative-convective model that includes the interaction of aerosols with radiation to reveal the mechanism of this dust/precipitation interaction feedback process and a Langevin equation is used to illustrate glacial climate destabilization by this mechanism. This theory explains the observed abrupt, bimodal, and memoryless nature of these transitions as well as their intrinsic connection with the hydrological cycle
Measuring the Hausdorff Dimension of Quantum Mechanical Paths
We measure the propagator length in imaginary time quantum mechanics by Monte
Carlo simulation on a lattice and extract the Hausdorff dimension . We
find that all local potentials fall into the same universality class giving
like the free motion. A velocity dependent action () in the path integral (e.g. electrons moving in
solids, or Brueckner's theory of nuclear matter) yields if and if . We discuss the
relevance of fractal pathes in solid state physics and in , in particular
for the Wilson loop in .Comment: uuencoded and compressed shell archive file. 8 pages with 7 figure
Training Custom Light Curve Models of SN Ia Sub-Populations Selected According to Host Galaxy Properties
Type Ia supernova (SN Ia) cosmology analyses include a luminosity step
function in their distance standardization process to account for an observed
yet unexplained difference in the post-standardization luminosities of SNe Ia
originating from different host galaxy populations (e.g., high-mass () versus low-mass galaxies). We present a novel method for
including host-mass correlations in the SALT3 light curve model used for
standardising SN Ia distances. We split the SALT3 training sample according to
host-mass, training independent models for the low- and high-host-mass samples.
Our models indicate that there are different average Si II spectral feature
strengths between the two populations, and that the average SED of SNe from
low-mass galaxies is bluer than the high-mass counterpart. We then use our
trained models to perform a SN cosmology analysis on the 3-year
spectroscopically confirmed Dark Energy Survey SN sample, treating SNe from
low- and high-mass host galaxies as separate populations throughout. We find
that our mass-split models reduce the Hubble residual scatter in the sample,
albeit at a low statistical significance. We do find a reduction in the
mass-correlated luminosity step but conclude that this arises from the
model-dependent re-definition of the fiducial SN absolute magnitude rather than
the models themselves. Our results stress the importance of adopting a standard
definition of the SN parameters () in order to extract the most
value out of the light curve modelling tools that are currently available and
to correctly interpret results that are fit with different models.Comment: 15 pages, accepted by MNRA
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