Observing Capabilities

This section summarizes the observing capabilities of the global gravitational-wave detector network as of early 2019. This as a quick reference to the anticipated commissioning and observing schedule, sensitivity to gravitational-wave transients, and sky localization accuracy, as described in the following external documents:

  • White Paper [1] on gravitational-wave data analysis and astrophysics
  • Living Review [2] on prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo, and KAGRA
  • Current O3 Schedule [3]

Timeline

The gravitational-wave observing schedule is divided into Observing Runs or epochs of months to years of operation at fixed sensitivity, down time for construction and commissioning, and transitional Engineering Runs between commissioning and observing runs. The long-term observing schedule is shown below. Since BNS mergers are a well-studied class of gravitational-wave signals, this figure gives the BNS range for each observing run.

Long-term observing schedule

Engineering Run 14 (ER14) started on 2019-03-04. The transition into Observing Run 3 (O3) occurred on 2019-04-01. O3 is planned to end on 2020-04-30.

During O3, we expect that three facilities (LHO, LLO, and Virgo) will observe for one year. It is possible that the Japanese KAGRA detector may come online and become part of the international gravitational-wave network at some point during O3. The near-term observing schedule is shown below, reproduced from [3].

Current observing schedule

Live Status

There are a handful of public web pages that report live status of the LIGO/Virgo detectors and alert infrastructure.

Sensitivity and Sky Localization Accuracy

The following O3 projections are adapted from the preprint version of the Living Review [4] on prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo, and KAGRA. The table below gives the range of each individual detector for BNS, NSBH, and BBH mergers, and unmodeled bursts.

Detector Range (Mpc)
BNS NSBH BBH Burst
LIGO 110–130 190-240 990-1200 80–90
Virgo 50 90 500 35
KAGRA 8–25 15-45 80-260 5-25

These ranges are given for the following fiducial signals:

BNS
A merger of two \(1.4 M_\odot\) NSs.
NSBH
A merger of a \(10 M_\odot\) BH and a \(1.4 M_\odot\) NS.
BBH
A merger of two \(30 M_\odot\) BHs.
Burst
A monochromatic signal at a frequency of 140 Hz carrying an energy of \(E_\mathrm{GW}=10^{-2} M_\odot c^2\).

Note

The range is defined in relation to the sensitive volume, or the surveyed space-time volume per unit detector time. The range is neither a luminosity distance nor a comoving distance.

Event Rates

See the O3 Observing Scenarios [4] paper for LIGO and Virgo’s most current estimates of astrophysical rates of compact binary mergers. The detection rate estimates contained in [2] and later updated in the O3 Observing Scenarios [4] paper embody estimates derived from the knowledge of mass, spin, and rate distributions available at the time. These estimates are regularly revised as our understanding of those distributions is enhanced with additional detections. Updates will also take into account the network evolution and actual advancement of the sensitivity of the instruments compared to projections in [2].

[1]LIGO Scientific Collaboration & Virgo Collaboration 2019, The LSC-Virgo White Paper on Gravitational Wave Data Analysis and Astrophysics. LIGO-T1900541-v2
[2](1, 2, 3) Abbott, B. P., Abbott, R., Abbott, T. D., et al. 2018, Living Rev. Rel., 21, 3. doi:10.1007/s41114-018-0012-9
[3](1, 2) LIGO Scientific Collaboration & Virgo Collaboration 2019, Current O3 Schedule. LIGO-G1901531-v1
[4](1, 2, 3) LIGO Scientific Collaboration & Virgo Collaboration 2019, Prospects for Observing and Localizing Gravitational-Wave Transients with Advanced LIGO, Advanced Virgo and KAGRA. arXiv:1304.0670
[5]Chen, H.-Y., Holz, D. E., et al. 2017, Distance measures in gravitational-wave astrophysics and cosmology. arXiv:1709.08079