ELUCID is a method to reconstruct the initial linear density field from an input nonlinear density field,
employing the Hamiltonian Markov Chain Monte Carlo (HMC) algorithm combined with Particle-mesh (PM) dynamics.
My talk will describe its application and the constrained N-body and gas simulations in the SDSS volume. I will
show how to use the reconstruction to understand galaxies...
The advent of the James Webb Space Telescope (JWST) has brought the study of early galaxy formation to a new level. Shortly after it began its scientific operation, JWST revealed a large number of candidate galaxies at redshift (z) greater than 11 when the universe was less than ~420 million years old, some of which could even be at z ~ 20 (age of the universe ~180 million years). This was...
I will introduce the neutral hydrogen (HI) intensity mapping technique and its potential to constrain cosmology across a huge range of scales and redshifts. I will then discuss the latest results using the MeerKAT telescope and plans for the next few years. I will conclude with an highlight of the measurements expected with a future SKA HI intensity mapping survey and its synergies with other...
Lyα Intensity Mapping with optical broad-band imaging
Intensity Mapping is a promising observational technique, consisting in the tracing of emission lines on large angular scales, without resolving any particular objects. In this talk, I will present a new method to perform Lyα intensity mapping by studying the fluctuations in the background of broad-band images versus the Lyα forest of...
The high-redshift nature of the post-reionization IGM makes it a promising avenue to constrain the nature of dark matter since nonlinearities are not as prominent as in low-redshift alternatives. Nevertheless, to fully unlock 21 cm intensity mapping and the Lyman-$\alpha$ forest, which are the two primary cosmological probes of the post-reionization era; we must first account for their...
We examine the cosmic evolution of the growth of perturbations with respect to matter content at early and recent past era of the Universe under the framework of non-zero torsion cosmology. Some cosmographic parameters are also discussed. To analyze this cosmic scenario, we formulate the cosmic models with two dark matter considerations and apply spherical collapse formalism. We explore that...
The primordial vorticity and gravity wave leave anisotropic imprints in the large-scale structure, known as the primordial fossils. The primordial vector and tensor fossils are directly sensitive to parity violations in the early Universe. I will present a new method to generate parity violating initial conditions for cosmological simulations and show that the tidal estimators can separate the...
We used more than 25 million galaxies in the Subaru Hyper Suprime-Cam (HSC) shear catalog in the redshift range up to z~1.5 to measure weak lensing distortion effects due to large-scale structures. We used the measured weak lensing signals to perform a blinded cosmology analysis to measure the cosmological parameters of the flat LambdaCDM model. To obtain a robust constraint on the...
The Dark Energy Spectroscopic Survey (DESI) will obtain optical spectra for about 40 million galaxies and quasars. From the 3-dimensional distribution of the galaxies, DESI will measure the expansion history over the past 11 billion years to constrain possible dark energy models. In this talk, I will give an overview of the DESI instrument and survey; I will discuss the early data release,...
The 2m-aperture Chinese Space Station Telescope (CSST) is a major science project of China Manned Space Program. It is planned to launch in 2025 and has a nominal mission lifetime of 10 years. During observations, the CSST will fly independently at a large distance from the space station. It can dock with the space station for servicing as scheduled or as needed. With a Cook-type three-mirror...
Recently, several studies reported a significant discrepancy between the clustering and lensing of the Baryon Oscillation Spectroscopic Survey (BOSS) galaxies in the Planck cosmology. We construct a simple yet powerful model based on the linear theory to assess whether this discrepancy points toward deviations from Planck. Focusing on scales $10{<}R{<}30\,h^{-1}\mathrm{Mpc}$, we model the...
Cosmic shear is a powerful tool for revealing matter distribution in the large-scale structure of the universe. Li et al. (2023) and Dalal et al. (2023) measured the tomographic cosmic shear correlation functions and power spectra, respectively, from the HSC-Y3 data, and then constrained the cosmological parameters from the model fitting. Although the small scale data has a high...
We present the Baryonic Acoustic Oscillations (BAO) measurements using the First Three Year data from the Dark Energy Survey (DES). We describe the data sample and the mock catalog used for BAO measurements. In addition to the tomographic analysis results, I will also present the alternative projective 3D correlation function analysis. The DES Y3 BAO measurement gives the most precise BAO...
I will present the details of the hybrid RSD model, which combines PT with N-body simulations. 1-template and emulator versions of the model will be presented.
The standard hot big bang predicts a background of relic neutrinos analogous to the CMB. At an average of ~300 neutrinos per cubic centimetre, these neutrinos are a formidable presence that can influence the evolution of the universe in many different ways. In this talk, I will discuss what one could learn about the neutrino sector from large-scale structure, as well as some recent...
The cosmic acceleration, first probed by observations of SNIa in 1998, is one of the most significant discoveries in modern sciences. In the past 25 years, extensive studies have been performed to unveil the physical origin of this surprising phenomenon, including studies on dark energy and modified gravity. In this talk, I will report the latest progress in this field, and focus on...
Rapid advances in deep learning have brought not only myriad powerful neural network models, but also breakthroughs that benefit established scientific research. In particular, automatic differentiation (AD) tools and computational accelerators like GPUs have facilitated forward modeling of the Universe with differentiable simulations. I will talk about our recent progress on developing...
Recently, I developed a non-linear multi-flow perturbation theory for massive neutrinos and other free-streaming particles, called Flows For The Masses. It bins their initial Fermi-Dirac distribution into discrete momenta, with neutrinos of each initial momentum treated as a separate fluid obeying the continuity and Euler equations of motion. I describe its non-linear corrections, based upon...
With increasing significance, the H0-tension between the Local Distance Ladder and Planck ΛCDM-analysis of the CMB points to a new principle of cosmological spacetime. Distinct from conventional extrapolations of general relativity in the Solar system, cosmological spacetime contains heat as a relic of the Big Bang based on Planck scale structures in black hole spacetimes. A path integral...
The talk will present a summery of the main results within the Scale Invariant Vacuum (SIV) paradigm as related to the Weyl Integrable Geometry (WIG) as an extension to the standard Einstein General Relativity (EGR). After a short sketch of the mathematical framework, the main results until 2023 [1] will be highlighted in relation to: the inflation within the SIV [2], the growth of the density...
The spatial distribution of galaxies contains a significant amount of information of the underlying cosmology. However, fully extracting this information can be challenging, especially at small scale due to the non-linearity of the dark matter dynamics, as well as the complicated physics of galaxy formation and evolution. I will introduce the emulator approach in the modeling of galaxy large...
