Reconstructing the Projected Dark Matter Field across 0.1–100 Mpc Scales from the SDSS Survey*
11 affiliations
- 1Peking University
- 2Shanghai Jiao Tong University
- 3Durham University
- 4Chinese Academy of Sciences
- 5Nanjing University
- 6University of Cambridge
- 7University College London
- 8University of Massachusetts
- 9INAF–Osservatorio Astronomico di Padova
- 10Hunan University
- 11Fudan University
Abstract
Dark matter sets the gravitational environment in which galaxies form and evolve, but cannot be observed directly. We present a conditional diffusion model that reconstructs the projected dark matter density field from the galaxy stellar-mass density field for direct application to galaxy surveys. The model is trained on CAMELS and validated on the independent IllustrisTNG300-1 simulation. Halo masses inferred from the reconstructed projected-aperture measurements agree well with the corresponding true values, with a scatter below 0.2 dex. On 100 kpc scales, reconstructed surface densities show a typical scatter of ∼0.3 dex in the regime most relevant for observations. We apply the model to Sloan Digital Sky Survey (SDSS) galaxies with M ⋆ ≥ 10 ⁹ M ⊙ in a contiguous low-redshift region. Averaging over 100 stochastic realizations, we reconstruct and publicly release a projected dark matter field covering 90 × 90 ( h − 1 Mpc ) 2 with a pixel size of 0.097 h ⁻¹ Mpc. This pixel area corresponds to the characteristic projected area of halos with masses of ∼10 10.6 h ⁻¹ M ⊙ . The map reveals the multiscale projected cosmic web, including cluster-scale overdensities, filaments, and voids. Projected-aperture masses are statistically consistent with SDSS group-catalog masses, while the derived halo mass function broadly matches mock-catalog expectations. The reconstructed projected potential places Coma in one of the deepest wells and near a convergence region of the inferred projected acceleration field, suggesting that the reconstruction retains both local overdensities and coherent large-scale projected gravitational structure. This work shows that diffusion-based dark matter reconstruction can be applied to real galaxy surveys, enabling halo-mass- and spatially resolved dark-matter-environment-based studies of galaxy evolution in SDSS and future wide-area surveys.
Related
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- Tighter Dark Matter Constraints from the Projected Mass Method: A Neural Network Enhanced Method for Galaxy Groups and Clusters
BibTeX
@article{zhao2026reconstructing,
title = {{Reconstructing the Projected Dark Matter Field across 0.1–100 Mpc Scales from the SDSS Survey*}},
author = {Kunyao Zhao and Yingjie Peng and Dingyi Zhao and Xiaohu Yang and Luis C. Ho and Kai Wang and Jing Dou and Zeyu Gao and Qiusheng Gu and Yukun Liu and Roberto Maiolino and Houjun Mo and Alvio Renzini and Canpo Su and Bitao Wang and Yu-Chen Wang and Bingxiao Xu and Feng Yuan and Xingye Zhu},
journal = {The Astrophysical Journal Letters},
year = {2026},
month = oct,
doi = {10.3847/2041-8213/aea8fe},
url = {https://iopscience.iop.org/article/10.3847/2041-8213/aea8fe},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Reconstructing the Projected Dark Matter Field across 0.1–100 Mpc Scales from the SDSS Survey*
AU - Kunyao Zhao
AU - Yingjie Peng
AU - Dingyi Zhao
AU - Xiaohu Yang
AU - Luis C. Ho
AU - Kai Wang
AU - Jing Dou
AU - Zeyu Gao
AU - Qiusheng Gu
AU - Yukun Liu
AU - Roberto Maiolino
AU - Houjun Mo
AU - Alvio Renzini
AU - Canpo Su
AU - Bitao Wang
AU - Yu-Chen Wang
AU - Bingxiao Xu
AU - Feng Yuan
AU - Xingye Zhu
PY - 2026
DA - 2026/10/08
JO - The Astrophysical Journal Letters
DO - 10.3847/2041-8213/aea8fe
UR - https://iopscience.iop.org/article/10.3847/2041-8213/aea8fe
AB - Dark matter sets the gravitational environment in which galaxies form and evolve, but cannot be observed directly. We present a conditional diffusion model that reconstructs the projected dark matter density field from the galaxy stellar-mass density field for direct application to galaxy surveys. The model is trained on CAMELS and validated on the independent IllustrisTNG300-1 simulation. Halo masses inferred from the reconstructed projected-aperture measurements agree well with the corresponding true values, with a scatter below 0.2 dex. On 100 kpc scales, reconstructed surface densities show a typical scatter of ∼0.3 dex in the regime most relevant for observations. We apply the model to Sloan Digital Sky Survey (SDSS) galaxies with M ⋆ ≥ 10 ⁹ M ⊙ in a contiguous low-redshift region. Averaging over 100 stochastic realizations, we reconstruct and publicly release a projected dark matter field covering 90 × 90 ( h − 1 Mpc ) 2 with a pixel size of 0.097 h ⁻¹ Mpc. This pixel area corresponds to the characteristic projected area of halos with masses of ∼10 10.6 h ⁻¹ M ⊙ . The map reveals the multiscale projected cosmic web, including cluster-scale overdensities, filaments, and voids. Projected-aperture masses are statistically consistent with SDSS group-catalog masses, while the derived halo mass function broadly matches mock-catalog expectations. The reconstructed projected potential places Coma in one of the deepest wells and near a convergence region of the inferred projected acceleration field, suggesting that the reconstruction retains both local overdensities and coherent large-scale projected gravitational structure. This work shows that diffusion-based dark matter reconstruction can be applied to real galaxy surveys, enabling halo-mass- and spatially resolved dark-matter-environment-based studies of galaxy evolution in SDSS and future wide-area surveys.
SN - 2041-8205
SN - 2041-8213
ER -