Abstract
Gravitational wave (GW) sources are an excellent probe of the luminosity distance and offer a novel measure of the Hubble constant,H0. This estimation ofH0from standard sirens requires an accurate estimation of the cosmological redshift of the host galaxy of the GW source after correcting for its peculiar velocity. The absence of an accurate peculiar velocity correction affects both the precision and accuracy of the measurement ofH0, particularly for nearby sources. Here, we propose a framework to incorporate such a peculiar velocity correction for GW sources. A first implementation of our method to the event GW170817, combined with observations taken with Very Large Baseline Interferometry (VLBI), leads to a revised value ofH0= 68.3−4.5+4.6km s−1Mpc−1. While this revision is minor, it demonstrates that our method makes it possible to obtain unbiased and accurate measurements ofH0at the precision required for the standard siren cosmology.
Highlights
Efforts to take an accurate measurement of the expansion rate of the Universe at the present epoch, known as the Hubble constant (H0), have been ongoing since the discovery of the expanding Universe1 by Lemaître (1927, 1931) and Hubble (1929)
Current measurements of H0 obtained using standard rulers anchored in the early Universe, such as cosmic microwave background (CMB), baryon acoustic oscillations (BAO, Planck Collaboration XVI 2014; Anderson et al 2014; Aubourg et al 2015; Planck Collaboration XIII 2016; Macaulay et al 2019), and Big Bang nucleosynthesis (BBN, Addison et al 2018; Abbott et al 2018a), differ from late-Universe probes using standard candles, such as supernovae (SN type-Ia, Reid et al 2009; Riess et al 2019) and strong lensing from the H0LiCOW project (Wong et al 2019), along with the use of the angular diameter distance between the
The binary neutron star, black hole-neutron star, and supermassive binary black hole mergers are all expected to have electromagnetic counterparts. This can lead to the identification of the host galaxy of the Gravitational wave (GW) source and the redshift to the GW source can be estimated from the electromagnetic spectra of the host using spectroscopic measurement by the relation 1 + z = λo/λe2
Summary
Efforts to take an accurate measurement of the expansion rate of the Universe at the present epoch, known as the Hubble constant (H0), have been ongoing since the discovery of the expanding Universe by Lemaître (1927, 1931) and Hubble (1929). This tension, statistically significant by more than 4σ, would necessitate a revision of the flat Lambda cold dark matter (ΛCDM) model of cosmology (Verde et al 2013, 2019; Bernal et al 2016; Di Valentino et al 2017; Kreisch et al 2020; Poulin et al 2019; Lin et al 2019; Agrawal et al 2019; Knox & Millea 2020) Whether this discrepancy is associated with systematic or calibration errors in either of the data sets or whether it indicates new physics is currently a subject of intense debate.
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