# TDCOSMO. I. An exploration of systematic uncertainties in the inference of *H*_{0} from time-delay cosmography

Research output: Contribution to journal › Article › peer-review

### Standard

**TDCOSMO. I. An exploration of systematic uncertainties in the inference of H_{0} from time-delay cosmography.** / Millon, M.; Galan, A.; Courbin, F.; Treu, T.; Suyu, S. H.; Ding, X.; Birrer, S.; Chen, G. C.-F.; Shajib, A. J.; Sluse, D.; Wong, K. C.; Agnello, A.; Auger, M. W.; Buckley-Geer, E. J.; Chan, J. H. H.; Collett, T.; Fassnacht, C. D.; Hilbert, S.; Koopmans, L. V. E.; Motta, V.; Mukherjee, S.; Rusu, C. E.; Sonnenfeld, A.; Spiniello, C.; Vyvere, L. Van de.

Research output: Contribution to journal › Article › peer-review

### Harvard

*H*

_{0}from time-delay cosmography',

*Astronomy and Astrophysics*, vol. 639, A101. https://doi.org/10.1051/0004-6361/201937351

### APA

*H*

_{0}from time-delay cosmography.

*Astronomy and Astrophysics*,

*639*, [A101]. https://doi.org/10.1051/0004-6361/201937351

### Vancouver

*H*

_{0}from time-delay cosmography. Astronomy and Astrophysics. 2020 Jul 16;639. A101. https://doi.org/10.1051/0004-6361/201937351

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### Bibtex

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### RIS

TY - JOUR

T1 - TDCOSMO. I. An exploration of systematic uncertainties in the inference of H0 from time-delay cosmography

AU - Millon, M.

AU - Galan, A.

AU - Courbin, F.

AU - Treu, T.

AU - Suyu, S. H.

AU - Ding, X.

AU - Birrer, S.

AU - Chen, G. C.-F.

AU - Shajib, A. J.

AU - Sluse, D.

AU - Wong, K. C.

AU - Agnello, A.

AU - Auger, M. W.

AU - Buckley-Geer, E. J.

AU - Chan, J. H. H.

AU - Collett, T.

AU - Fassnacht, C. D.

AU - Hilbert, S.

AU - Koopmans, L. V. E.

AU - Motta, V.

AU - Mukherjee, S.

AU - Rusu, C. E.

AU - Sonnenfeld, A.

AU - Spiniello, C.

AU - Vyvere, L. Van de

N1 - 19 pages, 9 figures, 4 tables, published in A&A

PY - 2020/7/16

Y1 - 2020/7/16

N2 - Time-delay cosmography of lensed quasars has achieved 2.4% precision on the measurement of the Hubble constant, H0. As part of an ongoing effort to uncover and control systematic uncertainties, we investigate three potential sources: 1- stellar kinematics, 2- line-of-sight effects, and 3- the deflector mass model. To meet this goal in a quantitative way, we reproduced the H0LiCOW/SHARP/STRIDES (hereafter TDCOSMO) procedures on a set of real and simulated data, and we find the following. First, stellar kinematics cannot be a dominant source of error or bias since we find that a systematic change of 10% of measured velocity dispersion leads to only a 0.7% shift on H0 from the seven lenses analyzed by TDCOSMO. Second, we find no bias to arise from incorrect estimation of the line-of-sight effects. Third, we show that elliptical composite (stars + dark matter halo), power-law, and cored power-law mass profiles have the flexibility to yield a broad range in H0 values. However, the TDCOSMO procedures that model the data with both composite and power-law mass profiles are informative. If the models agree, as we observe in real systems owing to the “bulge-halo” conspiracy, H0 is recovered precisely and accurately by both models. If the two models disagree, as in the case of some pathological models illustrated here, the TDCOSMO procedure either discriminates between them through the goodness of fit, or it accounts for the discrepancy in the final error bars provided by the analysis. This conclusion is consistent with a reanalysis of six of the TDCOSMO (real) lenses: the composite model yields H0 = 74.0−1.8+1.7 km s−1 Mpc−1, while the power-law model yields 74.2−1.6+1.6 km s−1 Mpc−1. In conclusion, we find no evidence of bias or errors larger than the current statistical uncertainties reported by TDCOSMO.

AB - Time-delay cosmography of lensed quasars has achieved 2.4% precision on the measurement of the Hubble constant, H0. As part of an ongoing effort to uncover and control systematic uncertainties, we investigate three potential sources: 1- stellar kinematics, 2- line-of-sight effects, and 3- the deflector mass model. To meet this goal in a quantitative way, we reproduced the H0LiCOW/SHARP/STRIDES (hereafter TDCOSMO) procedures on a set of real and simulated data, and we find the following. First, stellar kinematics cannot be a dominant source of error or bias since we find that a systematic change of 10% of measured velocity dispersion leads to only a 0.7% shift on H0 from the seven lenses analyzed by TDCOSMO. Second, we find no bias to arise from incorrect estimation of the line-of-sight effects. Third, we show that elliptical composite (stars + dark matter halo), power-law, and cored power-law mass profiles have the flexibility to yield a broad range in H0 values. However, the TDCOSMO procedures that model the data with both composite and power-law mass profiles are informative. If the models agree, as we observe in real systems owing to the “bulge-halo” conspiracy, H0 is recovered precisely and accurately by both models. If the two models disagree, as in the case of some pathological models illustrated here, the TDCOSMO procedure either discriminates between them through the goodness of fit, or it accounts for the discrepancy in the final error bars provided by the analysis. This conclusion is consistent with a reanalysis of six of the TDCOSMO (real) lenses: the composite model yields H0 = 74.0−1.8+1.7 km s−1 Mpc−1, while the power-law model yields 74.2−1.6+1.6 km s−1 Mpc−1. In conclusion, we find no evidence of bias or errors larger than the current statistical uncertainties reported by TDCOSMO.

KW - astro-ph.CO

KW - gravitational lensing: strong

KW - methods: data analysis

U2 - 10.1051/0004-6361/201937351

DO - 10.1051/0004-6361/201937351

M3 - Article

VL - 639

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

M1 - A101

ER -

ID: 22210596