arXiv subjects

Ben G. Patterson

Publications and source records attributed to Ben G. Patterson.

3 recordsLinked to original sources

arXiv2025

Observability of eccentricity in a population of merging compact binaries

We investigate the prospects of observing residual eccentricity in a population of compact binaries by calculating the power in the eccentric harmonics, following the methodology in arXiv:2411.04187. Although most observed compact binary coalescences are expected to circularize before entering the sensitivity band of the ground-based gravitational-wave (GW) detectors, dynamical interactions in dense star clusters can lead to a fraction of these binaries with non-negligible eccentricity at the time of detection. To quantify the observability of eccentricity, we simulate a population of merging compact binaries and identify those which have sufficient power in sub-dominant eccentric harmonics to be clearly distinguishable from quasi-circular systems. We consider a binary black hole (BBH) population derived from globular cluster simulations with residual eccentricity distribution obtained from Cluster Monte Carlo (CMC) catalogs as well as a fiducial log-uniform model. Assuming the LIGO-Virgo network of GW detectors with their sensitivities achieved during LIGO-Virgo-KAGRA (LVK) Observing Run (O4), we find that the BBH population with measurable eccentricity will have a significantly higher median eccentricity $e_{\mathrm{10Hz}}\sim 0.3$ (with $90\%$ range: $0.1 - 0.5$) and signal-to-noise ratio (SNR) $\sim 20$ ($90\%$ range: $13 - 57$) compared to the observable population of BBHs. We compare our predictions of the regions of parameter space where eccentricity is detectable with the claimed observations of eccentricity in GW events from third Gravitational Wave Transient Catalog (GWTC-3).

astro-ph.HE↗

arXiv2024

Identifying Eccentricity in Binary Black Hole mergers using a Harmonic Decomposition of the Gravitational Waveform

We show that the gravitational waveform emitted by a binary on an eccentric orbit can be naturally decomposed into a series of harmonics. The frequencies of these harmonics depend upon the radial frequency, $f_{\mathrm{r}}$, determined by the time to return to apoapsis, and the azimuthal frequency, $f_{\phi}$, determined by the time to complete one orbit relative to a fixed axis. These frequencies differ due to periapsis advance. Restricting to the (2, 2) multipole, we find that the frequencies can be expressed as $f = 2 f_{\phi} + k f_{\mathrm{r}}$. We introduce a straightforward method of generating these harmonics and show that the majority of the signal power is contained in the $k= -1, 0, 1$ harmonics for moderate eccentricities. We demonstrate that by filtering these three leading harmonics, we are able to obtain a good estimate of the orbital eccentricity from their relative amplitudes.

gr-qc↗

arXiv2023

Identifying LISA verification binaries among the Galactic population of double white dwarfs

Double white dwarfs (DWDs) will be the most numerous gravitational-wave (GW) sources for the Laser Interferometer Space Antenna (LISA). Most of the Galactic DWDs will be unresolved and will superpose to form a confusion noise foreground, the dominant LISA noise source around $\sim 0.5\mathrm{-}3\,\mathrm{mHz}$. A small fraction of these sources will stand out from the background and be individually detectable. Uniquely among GW sources, a handful of these binaries will be known in advance from electromagnetic (EM) observations and will be guaranteed sources of detectable GWs in the LISA band; these are known as verification binaries (VBs). High-cadence photometric surveys are continuously discovering new VB systems, and their number will continue to grow ahead of the launch of LISA. We analyse, in a fully Bayesian framework, all the currently known VB candidates with the latest design requirements for the LISA mission and find that 25 of the considered sources can be detected within a $4\,\mathrm{yr}$ observation time. We explore what can be expected from GW observations, both alone and in combination with EM observations, and estimate the VB's time to detection in the early months of LISA operations. We also show how VBs can be analysed in the case where their GW signals compete with many other unknown binary signals (both resolved and unresolved) from a realistic Galactic population of DWDs.

astro-ph.SR↗