SEARCH FOR GRAVITATIONAL-WAVE INSPIRAL SIGNALS ASSOCIATED WITH SHORT GAMMA-RAY BURSTS DURING LIGO'S FIFTH AND VIRGO'S FIRST SCIENCE RUN
Progenitor scenarios for short gamma-ray bursts (short GRBs) include coalescenses of two neutron stars or a neutron star and black hole, which would necessarily be accompanied by the emission of strong gravitational waves. We present a search for these known gravitational-wave signatures in temporal and directional coincidence with 22 GRBs that had sufficient gravitational-wave data available in multiple instruments during LIGO's fifth science run, S5, and Virgo's first science run, VSR1. We find no statistically significant gravitational-wave candidates within a [-5, +1) s window around the trigger time of any GRB. Using the Wilcoxon-Mann-Whitney U test, we find no evidence for an excess of weak gravitational-wave signals in our sample of GRBs. We exclude neutron star-black hole progenitors to a median 90% CL exclusion distance of 6.7 Mpc.

title: Automatic Alignment for the first science run of the Virgo interferometer
abstract: During the past few years a network of large-scale laser interferometers, including the Virgo detector, has been developed with the aim of detecting gravitational waves. To properly operate the detectors, the longitudinal and angular positions of the suspended detector test masses, the interferometer mirrors, must be kept within a small range from the operating point. The design of the Virgo angular control system, called Automatic Alignment is based on a modified version of the Anderson-Giordano technique, a wave-front sensing scheme which uses the modulation-demodulation technique. This paper will present the theoretical background of the Virgo Automatic Alignment system, the implementation issues and the performances observed during the first Virgo science run (VSR1). A total RMS of 4 × 10−2 to 3 × 10−3 μrad for all angular degrees of freedom has been achieved.

title: Automatic Alignment system during the second science run of the Virgo interferometer
abstract: In this paper the performances of the Automatic Alignment sensing and control system in the Virgo gravitational wave detector, during the second scientific run from July 7th 2009 to January 8th 2010, are described. The accuracy of the angular control loops fulfills the original Virgo requirements, reaching the accuracy of a few nano-radians for the most critical angular degrees of freedom, and the control noise is below the Virgo design sensitivity in the whole detection band.

title: Noise from scattered light in Virgo’s second science run data
abstract: Virgo is one of the large, ground-based interferometers aimed at detecting gravitational waves. One of the technical problems limiting its sensitivity is caused by light in the output beams which is backscattered by seismically excited surfaces and couples back into the main beam of the interferometer. The resulting noise was thoroughly studied, measured and mitigated before Virgo's second science run (VSR2). The residual noise during VSR2, which increases in periods with a large microseism activity, is accurately predicted by the theoretical model. The scattered light has been associated with transient events in the gravitational-wave signal of the interferometer.

title: Directional limits on persistent gravitational waves using LIGO S5 science data.
abstract: The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2-20×10(-50)  strain(2) Hz(-1) and 5-35×10(-49)  strain(2) Hz(-1) sr(-1) for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as ≈7×10(-25) in the most sensitive frequency range near 160 Hz.

title: Beating the Spin-down Limit on Gravitational Wave Emission from the Vela Pulsar
abstract: We present direct upper limits on gravitational wave emission from the Crab pulsar using data from the first 9 months of the fifth science run of the Laser Interferometer Gravitational-wave Observatory (LIGO). These limits are based on two searches. In the first we assume that the gravitational wave emission follows the observed radio timing, giving an upper limit on gravitational wave emission that beats indirect limits inferred from the spin-down and braking index of the pulsar and the energetics of the nebula. In the second we allow for a small mismatch between the gravitational and radio signal frequencies and interpret our results in the context of two possible gravitational wave emission mechanisms.

title: Electron scattering in the presence of an intense electromagnetic field
abstract: The general theory of electron scattering in the presence of an external electromagnetic field, provided by an intense laser beam, accompanied by absorption ofn photons, each with energy ħω is discussed. The calculation leads to many summations over intermediate states. A general method for exactly evaluating several sums is described in detail. Numerical results show that the cross-section varies with intensity in a power law fashion.