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Title: Time-domain modelling of Extreme-Mass-Ratio Inspirals for the Laser Interferometer Space Antenna
Authors: Priscilla Canizares, Carlos F. Sopuerta

When a stellar-mass compact object is captured by a supermassive black hole located in a galactic centre, the system losses energy and angular momentum by the emission of gravitational waves. Subsequently, the stellar compact object evolves inspiralling until plunging onto the massive black hole. These EMRI systems are expected to be one of the main sources of gravitational waves for the future space-based Laser Interferometer Space Antenna (LISA). However, the detection of EMRI signals will require of very accurate theoretical templates taking into account the gravitational self-force, which is the responsible of the stellar-compact object inspiral. Due to its potential applicability on EMRIs, the obtention of an efficient method to compute the scalar self-force acting on a point-like particle orbiting around a massive black hole is being object of increasing interest. We present here a review of our time-domain numerical technique to compute the self-force acting on a point-like particle and we show its suitability to deal with both circular and eccentric orbits.

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Laser Interferometer Space Antenna
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How to keep LISAs laser on target five million km away

A key technical challenge of the joint ESA-NASA LISA mission has been solved: how to maintain precise pointing of a laser beam across five million km of space.
The next-decade Laser Interferometer Space Antenna (LISA) mission will look for ripples in spacetime - their existence predicted by Albert Einstein - known as gravitational waves. A trio of identical spacecraft will fly five million km apart in an equilateral triangle formation, linked by laser beams.

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Title: LISA Observations of Supermassive Black Hole Growth
Authors: Miroslav Micic, Kelly Holley-Bockelmann, Steinn Sigurdsson

Based on a high resolution cosmological n-body simulation, we track the hierarchical growth of black holes in galaxy clusters from z=20 to z=0. We present a census of black holes as function of redshift and will determine their mass assembly history under a variety of assumptions regarding the importance of gas accretion in black hole growth, from early supercritical Eddington accretion to gas-poor hierarchical assembly. Following a galaxy merger, black holes are expected to form, inspiral and merge after strongly radiating energy via gravitational waves. For each binary black hole inspiral and merger, we determine the expected gravitational wave signal for the Laser Interferometer Space Antenna (LISA), and calculate the LISA event rate as a function of time. We will calculate the black hole mass assembly history for several black hole growth scenarios, so that we can explore tests to characterize each model observationally. In particular, we will study how well LISA observations will be able to distinguish between these very different assembly scenarios.

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Title: The LISA verification binaries
Authors: A. Stroeer, A. Vecchio

The Laser Interferometer Space Antenna (LISA) guarantees the detection of gravitational waves by monitoring a handful of known nearby galactic binary systems, the so-called "verification binaries".

Researchers consider the most updated information on the source parameters for the thirty more promising verification binaries. They investigate which of them are indeed guaranteed sources for LISA and estimate the accuracy of the additional information that can be extracted during the mission. Their analysis considers the two independent Michelson outputs that can be synthesised from the LISA constellation, and they model the LISA transfer function using the rigid adiabatic approximation.
They carry out extensive Monte Carlo simulations to explore the dependency of our results on unknown or poorly constrained source parameters. The researchers find that four sources -- RXJ0806.3+1527, V407 Vul, ES Cet and AM CVn -- are clearly detectable in one year of observation; RXJ0806.3+1527 should actually be observable in less than a week. For these sources LISA will also provide information on yet unknown parameters with an error between approximately 1 percent and 10 percent. Four additional binary systems -- HP Lib, 4U 1820-30, WZ Sge and KPD 1930+2752 -- might also be marginally detectable.

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-- Edited by Blobrana at 13:25, 2006-05-17

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