Impact of weak lensing on bright standard siren analyses
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arXiv
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| Format: | Preprint |
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2024
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| _version_ | 1866916308414627840 |
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| author | Mpetha, Charlie T. Congedo, Giuseppe Taylor, Andy Hendry, Martin A. |
| author_facet | Mpetha, Charlie T. Congedo, Giuseppe Taylor, Andy Hendry, Martin A. |
| contents | Gravitational waves from binary mergers at cosmological distances will experience weak lensing by large scale structure. This causes a (de-)magnification, $μ$, of the wave amplitude, and a degenerate modification to the inferred luminosity distance $d_L$. To address this the uncertainty on $d_L$ is increased according to the dispersion of the magnification distribution at the source redshift, $σ_μ$. But this term is dependent on cosmological parameters that are being constrained by gravitational wave "standard sirens", such as the Hubble parameter $H_0$, and the matter density fraction $Ω_m$. $σ_μ$ is also sensitive to the resolution of the simulation used for its calculation. Tension in the measured value of $H_0$ from independent datasets, and the present use of outdated cosmological simulations, suggest $σ_μ$ could be underestimated. We consider two classes of standard siren, supermassive black hole binary and binary neutron star mergers. Underestimating $H_0$ and $Ω_m$ when calculating $σ_μ$ increases the probability of finding a residual lensing bias on these parameters greater than $1σ$ by 1.5-3 times. Underestimating $σ_μ$ by using low resolution/small sky-area simulations can also significantly increase the probability of biased results. For neutron star mergers, the spread of possible biases is 0.25 km/s/Mpc, comparable to the forecasted uncertainty. Left uncorrected this effect limits the use of BNS mergers for precision cosmology. For supermassive black hole binaries, the spread of possible biases on $H_0$ is significant, 5 km/s/Mpc, but $O(200)$ observations are needed to reduce the variance below the bias. To achieve accurate sub-percent level precision on cosmological parameters using standard sirens, first much improved knowledge on the form of the magnification distribution and its dependence on cosmology is needed. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2402_19476 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Impact of weak lensing on bright standard siren analyses Mpetha, Charlie T. Congedo, Giuseppe Taylor, Andy Hendry, Martin A. Cosmology and Nongalactic Astrophysics Gravitational waves from binary mergers at cosmological distances will experience weak lensing by large scale structure. This causes a (de-)magnification, $μ$, of the wave amplitude, and a degenerate modification to the inferred luminosity distance $d_L$. To address this the uncertainty on $d_L$ is increased according to the dispersion of the magnification distribution at the source redshift, $σ_μ$. But this term is dependent on cosmological parameters that are being constrained by gravitational wave "standard sirens", such as the Hubble parameter $H_0$, and the matter density fraction $Ω_m$. $σ_μ$ is also sensitive to the resolution of the simulation used for its calculation. Tension in the measured value of $H_0$ from independent datasets, and the present use of outdated cosmological simulations, suggest $σ_μ$ could be underestimated. We consider two classes of standard siren, supermassive black hole binary and binary neutron star mergers. Underestimating $H_0$ and $Ω_m$ when calculating $σ_μ$ increases the probability of finding a residual lensing bias on these parameters greater than $1σ$ by 1.5-3 times. Underestimating $σ_μ$ by using low resolution/small sky-area simulations can also significantly increase the probability of biased results. For neutron star mergers, the spread of possible biases is 0.25 km/s/Mpc, comparable to the forecasted uncertainty. Left uncorrected this effect limits the use of BNS mergers for precision cosmology. For supermassive black hole binaries, the spread of possible biases on $H_0$ is significant, 5 km/s/Mpc, but $O(200)$ observations are needed to reduce the variance below the bias. To achieve accurate sub-percent level precision on cosmological parameters using standard sirens, first much improved knowledge on the form of the magnification distribution and its dependence on cosmology is needed. |
| title | Impact of weak lensing on bright standard siren analyses |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2402.19476 |