分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Weak lensing studies via cosmic voids are a promising probe of Modified Gravity (MG). The Excess Surface mass Density (ESD) is widely used as a lensing statistics in weak lensing researches. In this paper we use the ray-tracing method to study the ESD around voids in simulations based on the Cubic Galileon (CG) gravity. With the compilation of N-body simulation and ray-tracing method, changes on the structure formation and deflection angle resulting from MG can both be considered, making the extraction of lensing signals more realistic. We find good agreements between the measurement and theoretical prediction of ESD for CG gravity. Meanwhile, the effect on the deflection angle is found to be incomparable to that on the structure formation in CG, indicating an equivalence between ESD (statistics) and the projection of 3D dark matter density field for this gravity. Finally, we demonstrate that it is impossible to distinguish CG and General Relativity in our simulation with an effective survey area $\sim1550deg^2$ and a galaxy number density of $10arcmin^{-2}$, implying that void lensing statistics may not be the optimal probe on testing CG gravity. The methodology employed in this paper that combines N-body simulation and ray-tracing method can be a robust way to measure the lensing signals from simulations based on the MGs, and especially on that who significantly modifies the deflection angle.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Weak lensing studies via cosmic voids are a promising probe of Modified Gravity (MG). The Excess Surface mass Density (ESD) is widely used as a lensing statistics in weak lensing researches. In this paper we use the ray-tracing method to study the ESD around voids in simulations based on the Cubic Galileon (CG) gravity. With the compilation of N-body simulation and ray-tracing method, changes on the structure formation and deflection angle resulting from MG can both be considered, making the extraction of lensing signals more realistic. We find good agreements between the measurement and theoretical prediction of ESD for CG gravity. Meanwhile, the effect on the deflection angle is found to be incomparable to that on the structure formation in CG, indicating an equivalence between ESD (statistics) and the projection of 3D dark matter density field for this gravity. Finally, we demonstrate that it is impossible to distinguish CG and General Relativity in our simulation with an effective survey area $\sim1550deg^2$ and a galaxy number density of $10arcmin^{-2}$, implying that void lensing statistics may not be the optimal probe on testing CG gravity. The methodology employed in this paper that combines N-body simulation and ray-tracing method can be a robust way to measure the lensing signals from simulations based on the MGs, and especially on that who significantly modifies the deflection angle.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Neutral hydrogen (HI) intensity mapping is a promising technique to probe the large-scale structure of the Universe, improving our understanding on the late-time accelerated expansion. In this work, we first scrutinize how an alternative cosmology, interacting dark energy (IDE), can affect the 21-cm angular power spectrum relative to the concordance $\Lambda$CDM model. We re-derive the 21-cm brightness temperature fluctuation in the context of such interaction and uncover an extra new contribution. Then we estimate the noise level of three upcoming HI intensity mapping surveys, BINGO, SKA1-MID Band$\,$1 and Band$\,$2, respectively, and employ a Fisher matrix approach to forecast their constraints on the IDE model. We find that while $\textit{Planck}\,$ 2018 maintains its dominion over early-Universe parameter constraints, BINGO and SKA1-MID Band$\,$2 put complementary bounding to the latest CMB measurements on dark energy equation of state $w$, the interacting strength $\lambda_i$ and the reduced Hubble constant $h$, and SKA1-MID Band$\,$1 even outperforms $\textit{Planck}\,$ 2018 in these late-Universe parameter constraints. The expected minimum uncertainties are given by SKA1-MID Band$\,$1+$\textit{Planck}\,$: $\sim 0.34\%$ on $w$, $\sim 0.22\%$ on $h$, $\sim 0.64\%$ on HI bias $b_{\rm HI}$, and an absolute uncertainty of about $3\times10^{-4}$ ($7\times10^{-4}$) on $\lambda_{1}$ ($\lambda_{2}$). Moreover, we quantify the effects from systematics of the redshift bin number, redshift-space distortions, foreground residuals and uncertainties on the measured HI fraction, $\Omega_{\mathrm{HI}}(z)$. Our results indicate a bright prospect for HI intensity mapping surveys in constraining IDE, whether on their own or further by synergies with other measurements.
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