Towards a gravitational wave observatory designer: sensitivity limits of spaceborne detectors

Abstract

The most promising concept for low frequency (millihertz to hertz) gravitational wave observatories are laser interferometric detectors in space. It is usually assumed that the noise floor for such a detector is dominated by optical shot noise in the signal readout. For this to be true, a careful balance of mission parameters is crucial to keep all other parasitic disturbances below shot noise. We developed a web application that uses over 30 input parameters and considers many important technical noise sources and noise suppression techniques to derive a realistic position noise budget. It optimizes free parameters automatically and generates a detailed report on all individual noise contributions. Thus one can easily explore the entire parameter space and design a realistic gravitational wave observatory. In this document we describe the different parameters, present all underlying calculations, and compare the final observatory's sensitivity with astrophysical sources of gravitational waves. We use as an example parameters currently assumed to be likely applied to a space mission proposed to be launched in 2034 by the European Space Agency. The web application itself is publicly available on the Internet at http://spacegravity.org/designer. Future versions of the web application will Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. incorporate the frequency dependence of different noise sources and include a more detailed model of the observatory's residual acceleration noise.

Unveiling the gravitational universe at μ-Hz frequencies

“…This leaves room for spurious influences from laser relative intensity noise (estimated at 5 × 10 −8 at 2 MHz) and electronic noise of the photodetector (estimated at 1 pA/ √ Hz and 1 pV/ √ Hz) given a local oscillator laser power of ≈ 0.2 mW. [33] All these parameters are very similar to the LISA requirements. However, in order to receive 15 pW of laser power at the far spacecraft over a distance of 430 million kilometers, a significant increase in laser power and telescope diameter is necessary.…”

Probing the nature of black holes: Deep in the mHz gravitational-wave sky

“…The sensitivity curve was computed with the use of the LISA Performance Model (perf-lisa.in2p3.fr) and the sources were adapted from [41] brief standalone summary of the fundamental theories that are to be confronted with such observations.…”

“…1 Projected sky-averaged sensitivity curve for AMIGO and possible sources within its range [ 209 ]. The sensitivity curve was computed with the use of the LISA Performance Model (perf-lisa.in2p3.fr) and the sources were adapted from [ 41 ] …”

Coherent detection of the light backscattered by an optical surface

“…Due to the seismic activity of the Earth such large scale interferometer cannot be built on earth and thus, the outer space becomes the ultimate choice. One such large scale interferometer, named as Laser Interferometer Space Antenna (LISA) that will have interferometer arm lengths on the order of millions of kilometers was proposed by ESA with the help of NASA and European national space agencies and is currently under the initial phase of development [8,9,10].…”

“…For all these GW interferometric instruments, parasitic light [10,11,12,13,14] is a critical noise source because, as a first order approximation, it can induce phase measurement errors depending on the relative amplitude of these parasitic optical fields. By way of example, this means that phase uncertainties of the order of a few microradians can be induced by ultra-weak retroreflected or back-scattered light, the relative power of which is about 10 −12 .…”