Michele Vallisneri - Academia.edu (original) (raw)

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Papers by Michele Vallisneri

Foundations of Physics Letters, 2000

In special relativity, the definition of coordinate systems adapted to generic accelerated observ... more In special relativity, the definition of coordinate systems adapted to generic accelerated observers is a long-standing problem, which has found unequivocal solutions only for the simplest motions. We show that the Märzke-Wheeler construction, an extension of the ...

Physical Review D - PHYS REV D, 2005

Space-borne interferometric gravitational-wave detectors, sensitive in the low-frequency (mHz) ba... more Space-borne interferometric gravitational-wave detectors, sensitive in the low-frequency (mHz) band, will fly in the next decade. In these detectors, the spacecraft-to-spacecraft light-travel times will necessarily be unequal and time varying, and (because of aberration) will have different values on up- and down-links. In such unequal-armlength interferometers, laser-phase noise will be canceled by taking linear combinations of the laser-phase observables measured between pairs of spacecraft, appropriately time shifted by the light propagation times along the corresponding arms. This procedure, known as time-delay interferometry (TDI), requires an accurate knowledge of the light-time delays as functions of time. Here we propose a high-accuracy technique to estimate these time delays, and we study its use in the context of the Laser Interferometer Space Antenna (LISA) mission. We refer to this ranging technique, which relies on the TDI combinations themselves, as time-delay interfer...

Classical and Quantum Gravity - CLASS QUANTUM GRAVITY, 2004

One of the most exciting prospects for the LISA gravitational wave observatory is the detection o... more One of the most exciting prospects for the LISA gravitational wave observatory is the detection of gravitational radiation from the inspiral of a compact object into a supermassive black hole. The large inspiral parameter space and low amplitude of the signal make detection of these sources computationally challenging. We outline here a first-cut data analysis scheme that assumes realistic computational resources. In the context of this scheme, we estimate the signal-to-noise ratio that a source requires to pass our thresholds and be detected. Combining this with an estimate of the population of sources in the universe, we estimate the number of inspiral events that LISA could detect. The preliminary results are very encouraging---with the baseline design, LISA can see inspirals out to a redshift z = 1 and should detect over a thousand events during the mission lifetime.

Physical Review Letters, 2001

The evolution of a neutron-star r-mode driven unstable by gravitational radiation (GR) is studied... more The evolution of a neutron-star r-mode driven unstable by gravitational radiation (GR) is studied here using numerical solutions of the full nonlinear fluid equations. The dimensionless amplitude of the mode grows to order unity before strong shocks develop which quickly damp the mode. In this simulation the star loses about 40% of its initial angular momentum and 50% of its rotational kinetic energy before the mode is damped. The nonlinear evolution causes the fluid to develop strong differential rotation which is concentrated near the surface and poles of the star.

Physical Review D, 2004

The LISA time-delay-interferometry responses to a gravitational-wave signal are rewritten in a fo... more The LISA time-delay-interferometry responses to a gravitational-wave signal are rewritten in a form that accounts for the motion of the LISA constellation around the Sun; the responses are given in closed analytic forms valid for any frequency in the band accessible to LISA. We then present a complete procedure, based on the principle of maximum likelihood, to search for stellar-mass binary systems in the LISA data. We define the required optimal filters, the amplitude-maximized detection statistic (analogous to the F statistic used in pulsar searches with ground-based interferometers), and discuss the false-alarm and detection probabilities. We test the procedure in numerical simulations of gravitational-wave detection.

Living Reviews in Relativity, 2013

Classical and Quantum Gravity, 2008

... Stanislav Babak1, John G Baker2, Matthew J Benacquista3, Neil J Cornish4, Jeff Crowder5, Curt... more ... Stanislav Babak1, John G Baker2, Matthew J Benacquista3, Neil J Cornish4, Jeff Crowder5, Curt Cutler5,6, Shane L Larson7, Tyson B Littenberg4, Edward K Porter1, Michele Vallisneri5,6, Alberto Vecchio8,9 (the Mock LISA data challenge task force), Gerard Auger10, Leor ...

Classical and Quantum Gravity, 2012

The signal-to-noise ratio (SNR) is used in gravitational-wave observations as the basic figure of... more The signal-to-noise ratio (SNR) is used in gravitational-wave observations as the basic figure of merit for detection confidence and, together with the Fisher matrix, for the amount of physical information that can be extracted from a detected signal. SNRs are usually computed from a sensitivity curve, which describes the gravitational-wave amplitude needed by a monochromatic source of given frequency to achieve a threshold SNR. For interferometric spacebased detectors similar to LISA, which are sensitive to long-lived signals and have constantly changing position and orientation, exact SNRs need to be computed on a source-by-source basis. For convenience, most authors prefer to work with sky-averaged sensitivities, accepting inaccurate SNRs for individual sources and giving up control over the statistical distribution of SNRs for source populations. In this paper, we describe a straightforward end-to-end recipe to compute the nonsky-averaged sensitivity of interferometric space-based detectors of any geometry. This recipe includes the effects of spacecraft motion and of seasonal variations in the partially subtracted confusion foreground from Galactic binaries, and it can be used to generate a sampling distribution of sensitivities for a given source population. In effect, we derive error bars for the sky-averaged sensitivity curve, which provide a stringent statistical interpretation for previously unqualified statements about sky-averaged SNRs. As a worked-out example, we consider isotropic and Galactic-disk populations of monochromatic sources, as observed with the "classic LISA" configuration. We confirm that the (standard) inverserms average sensitivity for the isotropic population remains the same whether or not the LISA orbits are included in the computation. However, detector motion tightens the distribution of sensitivities, so for 50% of sources the sensitivity is within 30% of its average. For the Galactic-disk population, the average and distribution of the sensitivity for a moving detector turn out to be similar to the isotropic case.