The cosmic growth rate, which is related to peculiar velocity and is a primary scientific objective of galaxy spectroscopic surveys, can be inferred from the Redshift Space Distortion effect and the kinetic Sunyaev–Zel’dovich (kSZ) effect. However, the reconstruction noise power spectrum of the radial velocity field in kSZ is significantly dependent on the measurement of the small-scale galaxy-electron power spectrum $$P_{\text {ge}}.$$ In this study, we thoroughly discuss the enhancement of cosmic growth rate measurements facilitated by Fast Radio Bursts (FRBs), which probe the electron density of the universe along their propagation paths to provide crucial additional information on $$P_{\text {ge}}.$$ Subsequently, we utilize future spectroscopic surveys from the Chinese Space Station Telescope and the CMB-S4 experiment, combined with FRB dispersion measures, to achieve precise measurements of the cosmic growth rate at redshifts $$z_{\text {g}} = 0.15,\,0.45,\,0.75.$$ Employing Fisher matrix forecasting analysis, we anticipate that constraints on $$f\sigma _8$$ will reach a precision of 0.1% with a sample size of $$10^6$$ FRBs. Furthermore, we perform a global analysis using Markov Chain Monte Carlo methods to constrain key parameters of three distinct dark energy models and a modified gravity model based on cosmic growth rate measurements. The results demonstrate that these refined $$f\sigma _8$$ measurements considerably enhance the constraints on relevant cosmological parameters compared to those obtained from Planck CMB data. As the number of observed FRBs increases, alongside more precise galaxy surveys and next-generation CMB observations, new opportunities will arise for constraining cosmological models using the kSZ effect and for developing novel cosmological applications of FRBs.

China

Shi-Yuan Wang

Jun-Qing Xia

Measuring cosmic growth rate with CSST spectroscopic survey and fast radio burst

Axion-like particles (ALPs) are compelling candidates for dark matter with a broad range of possible masses and coupling strengths. These particles decay into two photons, contributing to cosmic background radiation, which may correlate with large-scale structure (LSS). ALPs with a mass around 1 eV decay into monochromatic photons in the near-infrared spectrum, which can be detected by the upcoming SPHEREx mission using line intensity mapping (LIM) technology. To search for ALP signals in SPHEREx, we calculate the cross angular power spectrum between the intensity maps and LSS probes. We employ several LSS probes, including galaxy clustering and weak lensing surveys conducted by the China Space Station Telescope (CSST), as well as CMB lensing performed by CMB-S4. Using a Fisher analysis, we place constraints on the ALP parameters, with uncertainties of $$\sigma (m_a) = 0.062$$ and $$\sigma (g_{a\gamma \gamma }) = 0.19$$ from the joint surveys. Our results suggest that the current bounds on $$g_{a\gamma \gamma }$$ could be improved by an order of magnitude for ALPs in the mass range around 1 eV. The cross-correlation also allows for detection of star formation lines observed by SPHEREx, providing constraints on the amplitude and redshift exponent of their power spectrum with uncertainties of $$\sigma (A_\text {astro}) = 0.004$$ and $$\sigma (\eta _\text {astro}) = 0.004$$ , respectively. Additionally, we consider intrinsic alignment (IA) as a systematic effect in the weak lensing survey. The IA amplitude and exponent are well constrained by the LIM-WL cross-correlation, yielding results of $$\sigma (A_{\text {IA}}) = 0.016$$ and $$\sigma (\eta _{\text {IA}}) = 0.025$$ , which offer significant improvements over previous works related to CSST.

Jiali Wu

Forecasts for decaying dark matter from cross-correlation between line intensity mapping and large scale structures surveys

We test the cosmic anisotropy in the dipole-modulated  $$\Lambda $$  <math> <mi>Λ</mi> </math>  CDM model and Finslerian cosmological model with the recently-released quasar sample. Based on the redshift tomographic method, the quasar sample is divided into two subsets  $$z \le z_{cut}$$  <math> <mrow> <mi>z</mi> <mo>≤</mo> <msub> <mi>z</mi> <mrow> <mi>cut</mi> </mrow> </msub> </mrow> </math>   and  $$z &gt; z_{cut}$$  <math> <mrow> <mi>z</mi> <mo>&gt;</mo> <msub> <mi>z</mi> <mrow> <mi>cut</mi> </mrow> </msub> </mrow> </math>   by different cutting redshifts. The dipole amplitudes of the two cosmological models from the subsets  $$z \le z_{cut}$$  <math> <mrow> <mi>z</mi> <mo>≤</mo> <msub> <mi>z</mi> <mrow> <mi>cut</mi> </mrow> </msub> </mrow> </math>   are very weak. We find that quasars at a higher redshift range may provide more detailed information about the dipole amplitude  $$A_D$$  <math> <msub> <mi>A</mi> <mi>D</mi> </msub> </math>  . The dipole directions of each cosmological model from the subsets  $$z \le 1.1$$  <math> <mrow> <mi>z</mi> <mo>≤</mo> <mn>1.1</mn> </mrow> </math>   and  $$z &gt; 1.1$$  <math> <mrow> <mi>z</mi> <mo>&gt;</mo> <mn>1.1</mn> </mrow> </math>   are deviated by  $$1\sigma $$  <math> <mrow> <mn>1</mn> <mi>σ</mi> </mrow> </math>   level. The Pantheon sample is combined with the two subsets. The dipole amplitude from the two combined datasets is also very weak. In the dipole-modulated  $$\Lambda $$  <math> <mi>Λ</mi> </math>  CDM model, the dipole direction from the combined dataset quasar at  $$z \le 1.1$$  <math> <mrow> <mi>z</mi> <mo>≤</mo> <mn>1.1</mn> </mrow> </math>   and Pantheon sample is far away from the one given by the Pantheon sample. In the Finslerian cosmological model, the dipole directions from the two combined datasets are close to the one in the Pantheon sample.

Dong Zhao

A tomographic test of cosmic anisotropy with the recently-released quasar sample

We test the anisotropy in the Finslerian cosmological model with the X-ray and ultraviolet (UV) fluxes of quasars. The 2015 and 2020 compilations of quasars are used in the cosmological constraints. We find that the dipole direction given by the 2015 quasar compilation is not far away from the one provided by the Pantheon sample and the angular differences are around  $$30^{\circ }$$  <math> <msup> <mn>30</mn> <mo>∘</mo> </msup> </math>  . The Pantheon sample is combined with quasars as the “standardized candles” to test the cosmic anisotropy. The results from two combined datasets are consistent. They show that the dipole anisotropy is weak in the Finslerian cosmological model. We investigate the Hubble constant  $$H_0$$  <math> <msub> <mi>H</mi> <mn>0</mn> </msub> </math>   in the Finslerian cosmological model. Though the central value of  $$H_0$$  <math> <msub> <mi>H</mi> <mn>0</mn> </msub> </math>   from the combination of six gravitationally lensed quasars, Pantheon sample, and 2020 quasar compilation decreases a little bit, it is consistent with the result from six gravitationally lensed quasars within statistical uncertainties.

Constraining the anisotropy of the Universe with the X-ray and UV fluxes of quasars

The possible slowing down of cosmic acceleration was widely studied. However, judgment on this effect in different dark energy parameterizations was very ambiguous. Moreover, the reason of generating these uncertainties was still unknown. In the present paper, we analyze the derivative of deceleration parameter <math><msup><mrow><mi>q</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>(</mo><mi>z</mi><mo>)</mo></math> using the Gaussian processes. This model-independent reconstruction suggests that no slowing down of acceleration is presented within 95% C.L. from the Union2.1 and JLA supernova data. However, <math><msup><mrow><mi>q</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>(</mo><mi>z</mi><mo>)</mo></math> from the observational <math><mi>H</mi><mo>(</mo><mi>z</mi><mo>)</mo></math> data is a little smaller than zero at 95% C.L., which indicates that future <math><mi>H</mi><mo>(</mo><mi>z</mi><mo>)</mo></math> data may have a potential to test this effect. From the evolution of <math><msup><mrow><mi>q</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>(</mo><mi>z</mi><mo>)</mo></math>, we present an interesting constraint on the dark energy and observational data. The physical constraint clearly solves the problem of why some dark energy models cannot produce this effect in previous work. Comparison between the constraint and observational data also shows that most of current data are not in the allowed regions. This implies a reason of why current data cannot convincingly measure this effect.

Ming-Jian Zhang

Physical condition for the slowing down of cosmic acceleration

In the present paper, we investigate the cosmographic problem using the bias–variance trade-off. We find that both the z -redshift and the y=z/(1+z) -redshift can present a small bias estimation. It means that the cosmography can describe the supernova data more accurately. Minimizing risk, it suggests that cosmography up to the second order is the best approximation. Forecasting the constraint from future measurements, we find that future supernova and redshift drift can significantly improve the constraint, thus having the potential to solve the cosmographic problem. We also exploit the values of cosmography on the deceleration parameter and equation of state of dark energy w ( z ). We find that supernova cosmography cannot give stable estimations on them. However, much useful information was obtained, such as that the cosmography favors a complicated dark energy with varying w ( z ), and the derivative dw/dz&lt;0 for low redshift. The cosmography is helpful to model the dark energy.

Hong Li

What do we know about cosmography

Searching for the signal of primordial gravitational waves in the B-modes (BB) power spectrum is one of the key scientific aims of the cosmic microwave background (CMB) polarization experiments. However, this could be easily contaminated by several foreground issues, such as the interstellar dust grains and the galactic cyclotron electrons. In this paper we study another mechanism, the cosmic birefringence, which can be introduced by a CPT-violating interaction between CMB photons and an external scalar field. Such kind of interaction could give rise to the rotation of the linear polarization state of CMB photons, and consequently induce the CMB BB power spectrum, which could mimic the signal of primordial gravitational waves at large scales. With the recently released polarization data of BICEP2 and the joint analysis data of BICEP2/Keck Array and Planck, we perform a global fitting analysis on constraining the tensor-to-scalar ratio r by considering the polarization rotation angle [ α(nˆ) ] which can be separated into a background isotropic part [ α¯ ] and a small anisotropic part [ Δα(nˆ) ]. Since the data of BICEP2 and Keck Array experiments have already been corrected by using the “self-calibration” method, here we mainly focus on the effects from the anisotropies of CMB polarization rotation angle. We find that including Δα(nˆ) in the analysis could slightly weaken the constraints on the tensor-to-scalar ratio r , when using current CMB polarization measurements. We also simulate the mock CMB data with the BICEP3-like sensitivity. Very interestingly, we find that if the effects of the anisotropic polarization rotation angle could not be taken into account properly in the analysis, the constraints on r will be dramatically biased. This implies that we need to break the degeneracy between the anisotropies of the CMB polarization rotation angle and the CMB primordial tensor perturbations, in order to measure the signal of primordial gravitational waves accurately.

Si-Yu Li

Mingzhe Li

Xinmin Zhang

Primordial gravitational waves measurements and anisotropies of CMB polarization rotation

In this paper, we study the case of single field inflation within the framework of modified gravity theory where the gravity part has an arbitrary form f(R) . Via a conformal transformation, this case can be transformed into its Einstein frame where it looks like a two-field inflation model. However, due to the existence of the isocurvature modes in such a multi-degree-of-freedom (m.d.o.f.) system, the (curvature) perturbations are not equivalent in two frames, so despite of its convenience, it is illegal to treat the perturbations in its Einstein frame as the “real” ones as we always do for pure f(R) theory or single field with nonminimal coupling. Here by pulling the results of curvature perturbations back into its original Jordan frame, we show explicitly the power spectrum and spectral index of the perturbations in the Jordan frame, as well as how it differs from the Einstein frame. We also fit our results with the newest Planck data. Since there is large parameter space in these models, we show that it is easy to fit the data very well.

Taotao Qiu

Perturbations of single-field inflation in modified gravity theory

None Supervisory Editors of Nuclear Physics B

Editorial note on “Lepton-flavor violation and (g−2)μ in the μν SSM” by Hai-Bin Zhang, Tai-Fu Feng, Shu-Min Zhao and Tie-Jun Gao [Nucl. Phys. B 873 (2) (2013) 300–324]