Can we measure individual black-hole spins from gravitational-wave observations?

Abstract

Measurements of black-hole spins from gravitational-wave observations of black-hole binaries with groundbased detectors are expected to be hampered by partial degeneracies in the gravitational-wave phasing: between the two component spins, and between the spins and the binary's mass ratio, at least for signals that are dominated by the binary's inspiral. Through the merger and ringdown, however, a different set of degeneracies apply. This suggests the possibility that, if the inspiral, merger and ringdown are all within the sensitive frequency band of a detector, we may be able to break these degeneracies and more accurately measure both spins. In this work we investigate our ability to measure individual spins for non-precessing binaries, for a range of configurations and signal strengths, and conclude that in general the spin of the larger black hole will be measurable (at best) with observations from Advanced LIGO and Virgo. This implies that in many applications waveform models parameterized by only one effective spin will be sufficient. Our work does not consider precessing binaries or sub-dominant harmonics, although we provide some arguments why we expect that these will not qualitatively change our conclusions. LIGO-P1500255

Tests of General Relativity with GW150914

“…[35] using NR waveforms from Ref. [36], enhanced with reduced-order modeling [37] to speed up waveform generation [38,39] (henceforth, EOBNR), and the single effective spin, precessing waveform model of Refs. [40][41][42] (henceforth, IMRPHENOM).…”

Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO

“…The GstLAL IMBHB analysis is based on a discrete bank of GW templates constructed over a total mass between 50 M ⊙ and 600 M ⊙ in the detector frame, with mass ratios less extreme than 1∶10, and with dimensionless spin χ 1;2 between −0.99 and 0.99, where positive values are aligned with the orbital angular momentum of the system and negative values are antialigned. The templates used in this search are a reduced-order model of a double aligned-spin effective-one-body waveform [24,25]. As a consequence of the noise characteristics at low frequencies [12], GstLAL began its analysis at a frequency of 15 Hz.…”

“…We evaluate the integral (3) using a Monte Carlo technique. The injected waveforms are generated using a spinaligned effective-one-body model [24], which is the waveform model used as a base for the reduced-order model [25] that the GstLAL search pipeline used for its template bank. Precession and higher-order modes are possibly important for IMBHB detection [39][40][41][42][43][44][45], particularly for sources with more extreme mass ratios; however, we neglect both effects due to current limitations in the waveform models.…”

Systematic bias due to nonspinning template waveforms in the gravitational wave parameter estimation for aligned-spin binary black holes

“…On the other hand, for aligned-spin systems, the two spins are strongly correlated [37,[40][41][42][43]. Thus, treating the effect of aligned-spins with a single spin parameter defined by…”