452 research outputs found
Multilayer coating facility for the HEFT hard x-ray telescope
A planar magnetron sputtering facility has been established at the Danish Space Research Institute (DSRI) for the production coating of depth graded multilayers on the thermally slumped glass segments which form the basis for the hard X-ray telescope on the HEFT balloon project. The facility is capable of coating 20-45 mirrors segments in each run. The coatings are optimized W/Si coatings. The paper describes the facility, the results of the calibration and presents data for the X-ray testing of flight mirrors
Using Markov chain Monte Carlo methods for estimating parameters with gravitational radiation data
We present a Bayesian approach to the problem of determining parameters for
coalescing binary systems observed with laser interferometric detectors. By
applying a Markov Chain Monte Carlo (MCMC) algorithm, specifically the Gibbs
sampler, we demonstrate the potential that MCMC techniques may hold for the
computation of posterior distributions of parameters of the binary system that
created the gravity radiation signal. We describe the use of the Gibbs sampler
method, and present examples whereby signals are detected and analyzed from
within noisy data.Comment: 21 pages, 10 figure
Searching for Gravitational Waves from Binary Inspirals with LIGO
We describe the current status of the search for gravitational waves from
inspiralling compact binary systems in LIGO data. We review the result from the
first scientific run of LIGO (S1). We present the goals of the search of data
taken in the second scientific run (S2) and describe the differences between
the methods used in S1 and S2.Comment: 9 pages, 2 figures. Published in proceedings of the 8th Gravitational
Wave Data Analysis Workshop, Milwaukee, WI, USA, 17-20 December 200
Stochastic Background Search Correlating ALLEGRO with LIGO Engineering Data
We describe the role of correlation measurements between the LIGO
interferometer in Livingston, LA, and the ALLEGRO resonant bar detector in
Baton Rouge, LA, in searches for a stochastic background of gravitational
waves. Such measurements provide a valuable complement to correlations between
interferometers at the two LIGO sites, since they are sensitive in a different,
higher, frequency band. Additionally, the variable orientation of the ALLEGRO
detector provides a means to distinguish gravitational wave correlations from
correlated environmental noise. We describe the analysis underway to set a
limit on the strength of a stochastic background at frequencies near 900 Hz
using ALLEGRO data and data from LIGO's E7 Engineering Run.Comment: 8 pages, 2 encapsulated PostScript figures, uses IOP class files,
submitted to the proceedings of the 7th Gravitational Wave Data Analysis
Workshop (which will be published in Classical and Quantum Gravity
Bayesian inference on compact binary inspiral gravitational radiation signals in interferometric data
Presented is a description of a Markov chain Monte Carlo (MCMC) parameter
estimation routine for use with interferometric gravitational radiational data
in searches for binary neutron star inspiral signals. Five parameters
associated with the inspiral can be estimated, and summary statistics are
produced. Advanced MCMC methods were implemented, including importance
resampling and prior distributions based on detection probability, in order to
increase the efficiency of the code. An example is presented from an
application using realistic, albeit fictitious, data.Comment: submitted to Classical and Quantum Gravity. 14 pages, 5 figure
NuSTAR Discovery of a Cyclotron Line in the Be/X-ray Binary RX J0520.5-6932 During Outburst
We present spectral and timing analysis of NuSTAR observations of RX
J0520.56932 in the 3-79 keV band collected during its outburst in January
2014. The target was observed on two epochs and we report the detection of a
cyclotron resonant scattering feature with central energies of keV and keV during the two
observations, respectively, corresponding to a magnetic field of G. The 3-79 keV luminosity of the system during the two epochs
assuming a nominal distance of 50 kpc was and
. Both values are much higher
than the critical luminosity of
above which a radiation dominated shock front may be expected. This adds a new
object to the sparse set of three systems that have a cyclotron line observed
at luminosities in excess of . A broad
( keV) Fe emission line is observed in the spectrum at a
central energy of keV in both epochs. The pulse profile
of the pulsar was observed to be highly asymmetric with a sharply rising and
slowly falling profile of the primary peak. We also observed minor variations
in the cyclotron line energy and width as a function of the rotation phase.% As
in observations of other cyclotron absorption line sources, there is a small
() phase difference between the peak of the cyclotron
energy variation and the peak of the flux variation.Comment: 9 pages, 4 figures, 6 tables. Accepted to Ap
The 0.3-30 Kev Spectra Of Powerful Starburst Galaxies:<i> Nustar </i>And<i> Chandra </i>Observations Of Ngc 3256 And Ngc 3310
NuSTAR discovery of an unusually steady long-term spin-up of the Be binary 2RXP J130159.6-635806
We present spectral and timing analysis of NuSTAR observations of the
accreting X-ray pulsar 2RXP J130159.6-635806. The source was serendipitously
observed during a campaign focused on the gamma-ray binary PSR B1259-63 and was
later targeted for a dedicated observation. The spectrum has a typical shape
for accreting X-ray pulsars, consisting of a simple power law with an
exponential cutoff starting at ~7 keV with a folding energy of E_fold=~18 keV.
There is also an indication of the presence of a 6.4 keV iron line in the
spectrum at the ~3 sigma significance level. NuSTAR measurements of the
pulsation period reveal that the pulsar has undergone a strong and steady
spin-up for the last 20 years. The pulsed fraction is estimated to be ~80%, and
is constant with energy up to 40 keV. The power density spectrum shows a break
towards higher frequencies relative to the current spin period. This, together
with steady persistent luminosity, points to a long-term mass accretion rate
high enough to bring the pulsar out of spin equilibrium.Comment: 13 pages, 7 figures, accepted for publication in The Astrophysical
Journa
Multilayer coating facility for the HEFT hard x-ray telescope
A planar magnetron sputtering facility has been established at the Danish Space Research Institute (DSRI) for the production coating of depth graded multilayers on the thermally slumped glass segments which form the basis for the hard X-ray telescope on the HEFT balloon project. The facility is capable of coating 20-45 mirrors segments in each run. The coatings are optimized W/Si coatings. The paper describes the facility, the results of the calibration and presents data for the X-ray testing of flight mirrors
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