Gravitational-wave sensitivity curves

Abstract: There are several common conventions in use by the gravitational-wave community to describe the amplitude of sources and the sensitivity of detectors. These are frequently confused. We outline the merits of and differences between the various quantities used for parameterizing noise curves and characterizing gravitational-wave amplitudes. We conclude by producing plots that consistently compare different detectors. Similar figures can be generated on-line for general use at \url{http://rhcole.com/apps/GWplotter}.

• The paper standardizes detector sensitivity measurements by clarifying conventions used in gravitational-wave astronomy.
• It compares characteristic strain, power spectral density, and spectral energy density to accurately interpret GW signals.
• The study introduces an online tool for custom sensitivity curve generation, aiding both novice and experienced researchers.

Analysis of "Gravitational-wave sensitivity curves"

The paper "Gravitational-wave sensitivity curves" authored by Moore, Cole, and Berry provides a comprehensive examination of the conventions utilized in the gravitational-wave (GW) community for quantifying detector sensitivity and source amplitude. This work is crucial in standardizing several approaches prevalent in the field, addressing the often-confused terminologies and presenting tools for better clarity in the depiction of GW detector capabilities.

The paper begins with the importance of consistent conventions to portray sensitivity curves used in GW astronomy effectively. The intricate relationship between the amplitude of a gravitational wave, defined by the strain $h$, and the sensitivity of detectors is underscored as a significant focus. This relationship affects both existing and future gravitational-wave observatories, crucial for multi-wavelength GW astronomy.

The authors dissect three major parametrizations: characteristic strain, power spectral density (PSD), and spectral energy density. Each carries specific implications in terms of physical interpretation and utility in astrophysical applications:

1. Characteristic Strain ($h_\mathrm{c}$): It incorporates the integration effect over an inspiraling GW signal, framing the parameter relative to the signal-to-noise ratio (SNR) on a log-log scale. Although effectively illustrative for GW detectability, it may present complications when applied to monochromatic sources due to undefined values.
2. Power Spectral Density ($\sqrt{S_{n}(f)}$): Frequently employed due to its simplicity, correlating directly to the noise characteristics in detectors. While intuitive for evaluating noise levels, it breaks direct correlation with SNR on a comparative plot for sources and detectors.
3. Spectral Energy Density ($S_{\mathrm{E}(f)$): Tapping into the physical essence of energy conveyed by waves, this metric, notably featured in stochastic background studies, inherently addresses the decrease in energy at lower frequencies.

For their analysis, the authors engage with current and potential GW sources, notably compact binaries, supernovae, and continuous sources like rotating neutron stars, along with stochastic backgrounds originating from cosmic phenomena. The discussion extends to detector classifications comprising ground-based (e.g., LIGO, Virgo), space-based observatories (e.g., LISA, eLISA), and pulsar timing arrays (PTAs). Each detector profile is methodically discussed, emphasizing the capabilities delineated via sensitivity curves and detecting frequencies.

The paper's practical facet shines through providing an online interface for custom sensitivity curve generation. This tool, defined at GWplotter, augments accessibility for both novice and seasoned researchers within the community.

In conclusion, the paper signifies an essential resource for researchers needing precise interpretation of GW detectors' sensing capabilities. It elucidates the disparity in conventions and offers a standardized platform for assessing and comparing various gravitational-wave phenomenologies. Advancements in these sensitivity curves can spearhead refined detector designs and strategic observations, steering the future of gravitational-wave astrophysics toward more profound discoveries and insights into our Universe's fabric.