宇宙学与河外天体物理
Primordial fluctuations frozen out during inflation re-enter the cosmological horizon and can collapse, leading to the formation of primordial black holes. We perform simulations of the direct collapse of over-dense regions re-entering the…
We present GIGA-Lens 2.0: a major upgrade to the GPU-accelerated Bayesian framework for modeling strong lensing systems that allows it to be run across multiple GPU nodes. We have succeeded in running GIGA-Lens 2.0 on 128 nodes or 512 A100…
We use an SVD decomposition of the low-redshift distance measurements from DESI BAO and three Type Ia supernova compilations to identify the leading linear directions probed by the data and to localize the tension with the LCDM CMB-anchored…
The bright-siren measurement of the Hubble constant from GW170817 (Abbott et al. 2017) assumes that switching from a volumetric to a uniform-in-$d_L$ luminosity-distance prior can be implemented by post-hoc reweighting of the baseline…
Galaxy clusters provide constraints on cosmology through their abundance as a function of mass and redshift. Parameter inference from cluster counts requires modelling the covariance entering the likelihood, including contributions from…
Line intensity mapping (LIM) has emerged as a powerful tool for surveying the large-scale structure of the Universe across cosmic time by measuring spatial fluctuations in the cumulative emission of spectral lines from unresolved sources or…
The cosmological distribution of neutral hydrogen (HI) during the post-reionization era is highly non-Gaussian due to the underlying non-linear structure formation, complex galaxy biasing, and potential primordial non-Gaussianity. One needs…
We show how to compute the compaction function within stochastic inflation, by solving the random field dynamics on stochastic binary trees. In this framework, the compaction function is directly related to the ratio of the volumes emerging…
In this chapter, we provide a comprehensive overview of the astrophysical and cosmological processes that shape the 21-cm signal during Cosmic Dawn and the Epoch of Reionization. We investigate both standard and exotic signatures…
We revisit cosmological perturbations in multi-field inflation using the $\delta N$ formalism. By extending the analysis to directions transverse to the inflationary trajectory, we explicitly account for the geometry of the final…
Fast radio bursts (FRBs) are emerging as powerful probes for cosmology. However, cosmological inference based on FRB dispersion measures (DMs) is limited by uncertainties in the Milky Way contribution, including those from the Galactic…
We develop an analysis framework based on {\em light-cone} galaxy mock catalogs constructed from linear theory simulations in order to accurately model the impact of primordial non-Gaussianity (PNG) on galaxy power spectrum on large scales.…
We investigate the impact of 104 localized FRBs on cosmological parameter estimation when combined with three established late-time probes: Cosmic Chronometers (CC), Type Ia Supernovae (SNe), and Baryon Acoustic Oscillations (BAO). By…
Baryonic feedback redistributes matter on small to mid cosmological scales, ultimately limiting inferences from Stage IV galaxy surveys. Direct baryon tracers are crucial for recovering cosmological signals masked by astrophysical effects,…
We investigate the cosmological evolution of matter perturbations in the modified gravity model $f(R,T^2)$, where $T^2=T_{\mu\nu}T^{\mu\nu}$ denotes the quadratic contraction of the energy--momentum tensor. Using the gauge-invariant 1+3…
We present a full-shape power-spectrum analysis of the eBOSS DR16 quasar sample with optimal redshift weights. The DR16 QSO catalog contains 343,708 quasars over $0.8<z<2.2$, a redshift interval broad enough to contain useful light-cone…
High-redshift galaxy clustering provides a powerful probe of the growth of structure, testing models of dark matter, dark energy, and galaxy formation during the epoch when the Universe was rapidly evolving. Emission line galaxies (ELGs)…
We report updated nHz gravitational wave (GW) significance, characterization, and interpretations using the customized chromatic-noise models (CNMs) developed in Larsen, Baier et al. (2026). for the NANOGrav 15-year data set. We find…
It has been noted in the literature that, if post-inflationary reheating is dominated by a stiff fluid with equation of state (EoS) $p>\rho/3$, then the predictions of Starobinsky inflation for the scalar spectral index could be made to…
Independent luminosity-distance probes beyond the Type Ia supernova range are needed to test cosmic expansion at high redshift. Type 1 AGN are abundant at \(z>2\), but their use for cosmology requires standardizable observables with…