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We develop a machine learning approach to reconstructing the cosmological initial conditions from late-time dark matter halo number density fields in redshift space, with the goal of improving sensitivity to cosmological parameters, and in…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-15 Jelte Bottema , Thomas Flöss , P. Daniel Meerburg

We propose to constrain the primordial (local-type) non-Gaussianity signal by first reconstructing the initial density field to remove the late time non-Gaussianities introduced by gravitational evolution. Our reconstruction algorithm…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-21 Xinyi Chen , Nikhil Padmanabhan , Daniel J. Eisenstein

We present a method to reconstruct the initial linear-regime matter density field from the late-time non-linearly evolved density field in which we channel the output of standard first-order reconstruction to a convolutional neural network…

Cosmology and Nongalactic Astrophysics · Physics 2023-10-23 Christopher J. Shallue , Daniel J. Eisenstein

Future Large Scale Structure surveys are expected to improve over current bounds on primordial non-Gaussianity (PNG), with a significant impact on our understanding of early Universe physics. The level of such improvements will however…

Herein, we present a deep-learning technique for reconstructing the dark-matter density field from the redshift-space distribution of dark-matter halos. We built a UNet-architecture neural network and trained it using the COmoving…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-21 Zitong Wang , Feng Shi , Xiaohu Yang , Qingyang Li , Yanming Liu , Xiaoping Li

We apply the time-renormalization group approach to study the effect of primordial non-Gaussianities in the non-linear evolution of cosmological dark matter density perturbations. This method improves the standard perturbation approach by…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Nicola Bartolo , J. P. Beltran Almeida , Sabino Matarrese , Massimo Pietroni , Antonio Riotto

We present a novel approach to estimate the value of primordial non-Gaussianity ($f_{\rm NL}$) parameter directly from the Cosmic Microwave Background (CMB) maps using a convolutional neural network (CNN). While traditional methods rely on…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-26 Chandan G. Nagarajappa , Yin-Zhe Ma

We present N-body cosmological numerical simulations including a primordial non-Gaussianity in the density fluctuation field quantified by the non-linear parameter $f_{NL}$. We have used MPGRAFIC code to produce initial conditions and the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 F. Fraschetti , J. M. Alimi , J. Courtin , P. S. Corasaniti

We construct a neural network to perform regression on the local dark-matter density field given line-of-sight peculiar velocities of dark-matter halos, biased tracers of the dark matter field. Our architecture combines a convolutional…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-27 Baptiste Barthe-Gold , Nhat-Minh Nguyen , Leander Thiele

Potential features in the primordial power spectrum have been searched for in galaxy surveys in recent years since these features can assist in understanding the nature of inflation. The null detection to date suggests that any such…

Cosmology and Nongalactic Astrophysics · Physics 2022-07-01 Yuhao Li , Hong-Ming Zhu , Baojiu Li

Local primordial non-Gaussianity, parameterised as $f_{\rm NL}^{\rm local}$, will be stringently constrained using state-of-the-art methods applied to next-generation galaxy redshift survey data. In this paper, in preparation for the…

We present an iterative method to reconstruct the linear-theory initial conditions from the late-time cosmological matter density field, with the intent of improving the recovery of the cosmic distance scale from the baryon acoustic…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-05 Ryuichiro Hada , Daniel J. Eisenstein

The distribution of matter that is measured through galaxy redshift and peculiar velocity surveys can be harnessed to learn about the physics of dark matter, dark energy, and the nature of gravity. To improve our understanding of the matter…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-04 Fei Qin , David Parkinson , Sungwook E. Hong , Cristiano G. Sabiu

We present a cosmic density field reconstruction method that augments the traditional reconstruction algorithms with a convolutional neural network (CNN). Following Shallue $\&$ Eisenstein (2022), the key component of our method is to use…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-05 Xinyi Chen , Fangzhou Zhu , Sasha Gaines , Nikhil Padmanabhan

We apply nonlinear reconstruction to the dark matter density field in redshift space and solve for the nonlinear mapping from the initial Lagrangian position to the final redshift space position. The reconstructed anisotropic field inferred…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-13 Hong-Ming Zhu , Yu Yu , Ue-Li Pen

We combine two Gaussianization techniques - Wavelet Non-Linear Wiener Filter (WNLWF) and density reconstruction - to quantify the recovery of Fisher information that is lost in the gravitational collapse. We compute a displacement fields,…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Joachim Harnois-Deraps , Hao-Ran Yu , Tong-Jie Zhang , Ue-Li Pen

We present a method to reconstruct the initial conditions of the universe using observed galaxy positions and luminosities under the assumption that the luminosities can be calibrated with weak lensing to give the mean halo mass. Our method…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-24 Chirag Modi , Yu Feng , Uros Seljak

We develop a deep learning technique to infer the non-linear velocity field from the dark matter density field. The deep learning architecture we use is an "U-net" style convolutional neural network, which consists of 15 convolution layers…

Cosmology and Nongalactic Astrophysics · Physics 2021-05-21 Ziyong Wu , Zhenyu Zhang , Shuyang Pan , Haitao Miao , Xin Wang , Cristiano G. Sabiu , Jaime Forero-Romero , Yang Wang , Xiao-Dong Li

We propose a UNet-based deep learning model to reconstruct the real-space dark matter (DM) velocity field from the redshift-space distribution of sparse DM halos. Using various statistical measures, we show that the reconstructed velocity…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-26 Xu Xiao , Jiacheng Ding , XiaoLin Luo , Sun Ke Lan , Liang Xiao , Shuai Liu , Xin Wang , Le Zhang , Xiao-Dong Li

Large-scale Fourier modes of the cosmic density field are of great value for learning about cosmology because of their well-understood relationship to fluctuations in the early universe. However, cosmic variance generally limits the…

Cosmology and Nongalactic Astrophysics · Physics 2022-01-05 Omar Darwish , Simon Foreman , Muntazir M. Abidi , Tobias Baldauf , Blake D. Sherwin , P. Daniel Meerburg
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