Lei Lei (雷磊)

Dark Star

As dark matter particles, WIMPs' annihilation ($\chi\chi \rightarrow \mathcal{SM}\overline{\mathcal{SM}}$) in the center of the first-generation dark matter halos may drive the first-generation luminous objects, known as Dark Stars (DS).

DS in JWST High-z Galaxies

JWST has found that galaxies with $z>11$ have excessively high star formation rates.

Could this be caused by Dark Stars?

The answer is that DS cannot fully explain the star formation rate observed by JWST, because JWST requires a large number of DS with too high temperatures and too massive, and after the collapse of these celestial bodies, they would exceed the current MACHO limits. Lei Lei, et al. (2025a).

Non-parametric Density Profile via Strong Lensing

Strong gravitational lensing is a great method for studying dark matter, because it can probe the density distribution of dark matter in distant galaxies.

The reconstructed density profile features a characteristic kiloparsec-scale core ($r_c \approx 0.5 \, \rm kpc$), suggesting the core formed with Self-interacting dark matter (SIDM). Lei Lei, et al. (2025b).

Axionlike Particles' X-Ray Emission from Stars

Axion-like particles (ALPs) may be produced in the hot cores of stars and become bound to form ALP clouds, whose decay could potentially generate observable X-ray emission line.

We have detected a potential signal, but further observations are needed for confirmation. We have also obtained the currently strongest limits on the ALP-photon conversion rate. Yu-Xuan Chen, Lei Lei, et al. (2025).

Cosmological Coupling of SMBH: DE source?

The origin of dark energy (DE) is unknown; could its source be astrophysical processes or fundamental fields? Could SMBHs be the source of dark energy?

Test SMBH cosmological coupling with JWST High-z AGNs

We found that the possibility of cosmologically coupled black holes is very small, meaning that it is unlikely for black holes to produce dark energy through a coupling to the cosmological scale factor via mass growth.

Additionally, we found that a new class of small red dots discovered by JWST, with their unique evolutionary paths, can explain phenomena that were mistakenly interpreted as cosmological growth of black hole mass. Lei Lei, et al. (2024).

Electromagnetic Coupling of DE induce Fine Structure Constant $\alpha$ Varying

JWST provides spectra of high-redshift galaxies, which can be used to constrain the variation of the fine-structure constant in the early universe compared to the present using atomic fine-structure lines (such as the O [III] emission line).

We found no evidence of changes in fine structure. We have the strongest current limit on the electromagnetic coupling strength of dark energy, improving the constraint from the CMB by four orders of magnitude. Ze-Fan Wang, Lei Lei, et al. (2024).

Covarying Coupling Constants and Tired Light (CCC+TL):

The high-redshift galaxies observed by JWST have relatively small apparent diameters. To explain this phenomenon, CCC+TL modifying the angular diameter distance of the universe to provide an explanation.

Test CCC+TL cosmological model with $H(z)$

We found that this model cannot self-consistently fit the SN and $H(z)$ data at the same time. Among them, the light speed change index $\alpha_{CCC}$ has a tension of $>8\sigma$ between the best fitting values ​​of SN and $H(z)$, indicating that the evolution of the apparent diameter of JWST galaxies is more likely to be caused by galaxy physics rather than the cosmological model. Lei Lei, et al. (2025).

JWST is Challenging $\Lambda$CDM ?

JWST found a large amount of massive/early high-redshift galaxies, which was identified challengs for $\Lambda$CDM.

JWST SFE excesses

Our analysis found that the JWST galaxy density still does not exceed $\Lambda$CDM, but the star formation efficiency (SFE) is still significantly different from the low redshift. Yi-Ying Wang, Lei Lei, et al. (2023).

JWST massive galaxy & nHz GW: Cosmic String?

Cosmic strings struggle to simultaneously explain nHz gravitational waves and the high-redshift galaxies observed by JWST, which suggests that the gravitational waves are not caused by cosmic strings, or that the massive galaxies observed by JWST are unrelated to cosmic strings. Zi-Wei Wang, Lei Lei, et al. (2023).

New Measurement of $H(z)$

The new measurement of $H(z)$ with DESI DR1 has a precision of ~6%. Ze-Fan Wang, Lei Lei, et al. (2026).

WFST (Mozi Survey, USTC & PMO) Lei Lei, et al. (2023) & Mephisto (YNU) Limiting Magnitudes Lei Lei, et al. (2021).