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A Hubble constant measurement from superluminal motion of the jet in GW170817

Hotokezaka, K. and Nakar, E. and Gottlieb, O. and Nissanke, S. and Masuda, K. and Hallinan, G. and Mooley, K. P. and Deller, A. T. (2019) A Hubble constant measurement from superluminal motion of the jet in GW170817. Nature Astronomy, 3 (10). pp. 940-944. ISSN 2397-3366.

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The Hubble constant (H₀) measures the current expansion rate of the Universe, and plays a fundamental role in cosmology. Tremendous effort has been dedicated over the past decades to measure H₀ (refs. 1-10). Gravitational wave (GW) sources accompanied by electromagnetic (EM) counterparts offer an independent standard siren measurement of H₀ (refs. 11-13), as demonstrated following the discovery of the neutron star merger, GW170817 (refs. 14-16). This measurement does not assume a cosmological model and is independent of a cosmic distance ladder. The first joint analysis of the GW signal from GW170817 and its EM localization led to a measurement of H₀=74⁺¹⁶₋₈kms⁻¹Mpc⁻¹ (median and symmetric 68% credible interval)13. In this analysis, the degeneracy in the GW signal between the source distance and the observing angle dominated the H₀ measurement uncertainty. Recently, tight constraints on the observing angle using high angular resolution imaging of the radio counterpart of GW170817 have been obtained17. Here, we report an improved measurement H₀=70.3^(+5.3)_(−5.0)kms⁻¹Mpc⁻¹ by using these new radio observations, combined with the previous GW and EM data. We estimate that 15 more GW170817-like events, having radio images and light curve data, as compared with 50–100 GW events without such data18,19, will potentially resolve the tension between the Planck and Cepheid–supernova measurements.

Item Type:Article
Related URLs:
URLURL TypeDescription ReadCube access Paper
Hotokezaka, K.0000-0002-2502-3730
Nakar, E.0000-0002-4534-7089
Gottlieb, O.0000-0003-3115-2456
Masuda, K.0000-0003-1298-9699
Hallinan, G.0000-0002-7083-4049
Mooley, K. P.0000-0002-2557-5180
Deller, A. T.0000-0001-9434-3837
Additional Information:© 2019 Springer Nature Limited. Received 26 November 2018; Accepted 16 May 2019; Published 08 July 2019; Issue Date October 2019. Data availability: MCMC samples are available from the corresponding author on request. Code availability: The codes used for generating the synthetic light curves are currently being readied for public release. Markov chain Monte Carlo Ensemble sampler: emcee. We are grateful to D. Brown, C. Hirata, V. Scowcroft, P. Shawhan, D. Spergel and H. Peiris for useful discussions. We thank the LIGO Scientific and Virgo Collaborations for public access to their data products. K.H. is supported by the Lyman Spitzer Jr. Fellowship at the Department of Astrophysical Sciences, Princeton University. E.N. and O.G. are supported by the I-Core center of excellence of the CHE-ISF. S.N. is grateful for support from NWO VIDI and TOP Grants of the Innovational Research Incentives Scheme (Vernieuwingsimpuls) financed by the Netherlands Organization for Scientific Research (NWO). The work of K.M. is supported by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute, under contract with the California Institute of Technology (Caltech)/Jet Propulsion Laboratory (JPL). G.H. acknowledges the support of NSF award AST-1654815. A.T.D. is the recipient of an Australian Research Council Future Fellowship (FT150100415). Author Contributions: K.H. carried out MCMC simulations with the synthetic models. E.N. and O.G. derived an analytic model and carried out hydrodynamic simulations to derive constraints on the observing angle. K.H. and K.M. analysed the posterior samples and calculated H0. G.H., K.P.M. and A.T.D. provided the input observational data. K.H., E.N., S.N. and G.H. wrote the paper. All co-authors discussed the results and provided comments on the manuscript. The authors declare no competing interests.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Princeton UniversityUNSPECIFIED
Isreal Science FoundationUNSPECIFIED
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
Australian Research CouncilFT150100415
Jansky FellowshipUNSPECIFIED
Subject Keywords:Compact astrophysical objects; Cosmology; High-energy astrophysics; Transient astrophysical phenomena
Issue or Number:10
Record Number:CaltechAUTHORS:20180905-132851528
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89394
Deposited By: Tony Diaz
Deposited On:05 Sep 2018 20:44
Last Modified:09 Mar 2020 13:18

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