Sensitivity
eLISA/NGO's all-sky field of view ensures observation in its frequency window of every gravitational wave source, without the need of compromising between observations. Its coherent observation mode allows resolving and distinguishing overlapping signals and locating them on the sky.
eLISA/NGO is designed to measure gravitational radiation over a broad band at low frequencies, from about 0.1 mHz to 1 Hz, a band where the Universe is richly populated by strong sources of gravitational waves.
eLISA/NGO can achieve 10-21 strain resolution by measuring displacements of the order of fractions of a picometer. Its observations in the quiet environment of space will not be disturbed by seismic and gravity-gradient noise. Thus eLISA/NGO's unparalleled sensitivity will allow studying sources within the Galaxy and up to the edge of the visible Universe.
eLISA/NGO’s wide frequency band – four decades in frequency, equivalent to the span from near infrared to radio frequency in the electromagnetic sector – will enable astronomers to study similar sources of widely different masses and cosmological redshifts.
As gravitational waves propagate unhindered through all regions of time and space, eLISA/NGO can sense waves from the densest regions of matter, the earliest stages of the Big Bang, and the most extreme warpings of spacetime near black holes. In particular, eLISA/NGO can observe objects that are shielded from electromagnetic observations by other stars or dust, such as binary systems close to or beyond the galactic center.
eLISA/NGO can achieve the requisite approximate 3 x 10-20 /√Hz strain sensitivity (averaged over all sky locations and polarisations), which allows to detect a strain of about 3.7 x 10-24 in a 2-year measurement with a Signal to Noise Ratio (SNR) of 1, in part, through a phase resolution of about 10 µcycle/√Hz with 1 µm wavelength light, resulting in a displacement sensitivity of 11 x 10-12 m/√Hz over a path length of 1 x 106 m. The achievable reductions of disturbances on test masses and the achievable displacement sensitivities by the laser ranging system yield a useful measurement bandwidth in the frequency range from 3 × 10–5 Hz to 1 Hz. (The requirement is 10–4 Hz to 1 Hz; the goal is 3 × 10–5 Hz to 1 Hz.)
