Dec 11 – 15, 2023
Tsung-Dao Lee Institute
Asia/Shanghai timezone

Stochastic Gravitational Wave Background from Stellar Compact Binaries and Gravitational Wave Multiband Observations from Stellar Binary Black Holes

Dec 15, 2023, 2:45 PM
Poster Poster


Yuetong Zhao


The detection of gravitational wave (GW) signals from merging stellar compact binary objects by aLIGO starts a new era of gravitational wave astronomy. The cosmic stellar compact binaries in their inspiral-merger-ringdown stages radiate GWs in the low-, middle- and high-frequency ($10^{-3}$-$10^{-1}$-$1000$ Hz) bands and produce a stochastic GW background (GWB), which is an important scientific target for the low-frequency (e.g. LISA/Taiji/TianQin) and high-frequency (e.g. aLIGO/Virgo/KAGRA/ET/CE) GW detectors. The multiband observations of the compact binaries provide us more information about their intrinsic physical properties and extrinsic configuration parameters compared to single-band observations. We investigate the effect on the GWB from the eccentric stellar compact binaries originated from different formation channels and the prospects of multiband observations by combining the low-, middle-, and high-frequency observations all together.
We estimate the GWB from both dynamically formed BBHs in dense stellar environment and those BBHs formed from the evolution of massive binary stars (EMBS) channel in the field, and the binary neutron stars originated from the EMBS channel. We find that the eccentric stellar compact binaries may influence the shape of GWB energy density spectrum at the low-frequency band. The eccentric stellar compact binaries form a double power law GWB, which is different from the one with canonical power index $2/3$ predicated from circular ones. The model with large fraction of highly eccentric dynamically formed BBHs predicates the GWB with large deviation from $2/3$ at the low-frequency band. We also predict that LISA, Taiji, and TianQin may detect the GWB with signal-to-noise ratio ($\rho$) $\geq 274$, $255$, and $21$ under $5$ years observations. Besides, we estimate the detectability and parameter estimation accuracy of BBHs in low-frequency band, middle-frequency band, and multiband observations. Combing the low-frequency (LISA-Taiji network, i.e., LT) and middle- frequency (AMIGO) band observations, LT-AMIGO will detect $5−33$ multiband BBHs, which are BBHs with $\rho \geq 5$ in both LT and AMIGO bands. The multiband observations will improve the estimation of localization and other parameter measurement precision for multiband BBHs. For example, compared with LT/AMIGO/ET-CE, LT- AMIGO-ET-CE may improve the localization by a factor ∼ $10^5$/$10^6$/$10^2$ and the redshifted chirp mass mea- surement precision by a factor ∼ $100$/$15$/$4$. The high precision of localizations and luminosity distance measurements for some BBHs via the LT-AMIGO-ET-CE multiband observations may help to identify their host galaxies directly from GW observations.

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