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Peculiar velocities of galaxies and halos can be reconstructed from their spatial distribution alone. This technique is analogous to the baryon acoustic oscillations (BAO) reconstruction, using the continuity equation to connect density and…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-24 Bernardita Ried Guachalla , Emmanuel Schaan , Boryana Hadzhiyska , Simone Ferraro

KSZ velocity reconstruction is a recently proposed method for mapping the largest-scale modes of the universe, by applying a quadratic estimator $\hat{v}_r$ to the small-scale CMB and a galaxy catalog. We implement kSZ velocity…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-14 Utkarsh Giri , Kendrick M. Smith

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

The kinetic Sunyaev-Zel'dovich (kSZ) effect offers an indirect way to reconstruct large-scale cosmic velocities, by correlating high-resolution CMB temperature maps with galaxy surveys. In this work, we present the first three-dimensional…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-30 Selim C. Hotinli , Kendrick M. Smith , Simone Ferraro

We propose a new velocity reconstruction method based on the displacement estimation by recently developed methods. The velocity is first reconstructed by transfer functions in Lagrangian space and then mapped into Eulerian space. High…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-01 Yu Yu , Hong-Ming Zhu

Reconstructing the galaxy peculiar velocity field from the distribution of large-scale structure plays an important role in cosmology. On one hand, it gives us an insight into structure formation and gravity; on the other, it allows us to…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-20 Boryana Hadzhiyska , Simone Ferraro , Bernardita Ried Guachalla , Emmanuel Schaan

We discuss an implementation of a deep learning framework to gain insight into dark matter (DM) structure formation. We investigate the contribution of velocity and density field information to the construction of the halo mass function…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-13 Saba Etezad-Razavi , Erfan Abbasgholinejad , Mohammad-Hadi Sotoudeh , Farbod Hassani , Sadegh Raeisi , Shant Baghram

We explore the potential of cross-correlating galaxies and peculiar velocities on non-linear scales to enhance cosmological constraints. Leveraging the \textsc{AbacusSummit} simulation suite and the halo occupation distribution (HOD)…

The peculiar velocities of dark matter halos are crucial to study many issues in cosmology and galaxy evolution. In this study, by using the state-of-the-art deep learning technique, a UNet-based neural network, we propose to reconstruct…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-10 Ziyong Wu , Liang Xiao , Xu Xiao , Jie Wang , Xi Kang , Yang Wang , Xin Wang , Le Zhang , Xiao-Dong Li

We propose a new method to recover the cosmological initial conditions of the presently observed galaxy distribution, which can serve to run constrained simulations of the Local Universe. Our method, the Reverse Zeldovich Approximation…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Timur Doumler , Yehuda Hoffman , Helene Courtois , Stefan Gottloeber

We present a forward-modelled velocity field reconstruction algorithm that performs the reconstruction of the mass density field using only peculiar velocity data. Our method consistently accounts for the inhomogeneous Malmquist bias using…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-01 Supranta S. Boruah , Guilhem Lavaux , Michael J. Hudson

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

The peculiar velocity field of the local Universe provides direct insights into its matter distribution and the underlying theory of gravity, and is essential in cosmological analyses for modelling deviations from the Hubble flow. Numerous…

Reconstructing the density fluctuations in the early Universe that evolved into the distribution of galaxies we see today is a challenge of modern cosmology [ref.]. An accurate reconstruction would allow us to test cosmological models by…

Astrophysics · Physics 2015-06-24 Uriel Frisch , Sabino Matarrese , Roya Mohayaee , Andrei Sobolevski

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

When measuring the value of the Hubble parameter, $H_0$, it is necessary to know the recession velocity free of the effects of peculiar velocities. In this work, we study different models of peculiar velocity in the local Universe. In…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-18 Supranta S. Boruah , Michael J. Hudson , Guilhem Lavaux

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

In previous works we proposed the Reverse Zeldovich Approximation (RZA) method, which can be used to estimate the cosmological initial conditions underlying the galaxy distribution in the Local Universe using peculiar velocity data. In this…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Timur Doumler , Stefan Gottloeber , Yehuda Hoffman , Helene Courtois

The structural and dynamic properties of the dark matter halos, though an important ingredient in understanding large-scale structure formation, require more conservative particle resolution than those required by halo mass alone in a…

Cosmology and Nongalactic Astrophysics · Physics 2022-11-23 Sujatha Ramakrishnan , Premvijay Velmani
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