399 citations · 1.6k across the 65 of their papers we have counts for
25 papers · 1 filter
The Adaptive TreePM: An Adaptive Resolution Code for Cosmological N-body Simulations
J. S. Bagla, Nishikanta Khandai
Cosmological N-Body simulations are used for a variety of applications. Indeed progress in the study of large scale structures and galaxy formation would have been very limited wit…
Effects of the size of cosmological N-Body simulations on physical quantities - III: Skewness
J. S. Bagla, Jayanti Prasad, Nishikanta Khandai
N-Body simulations are an important tool in the study of formation of large scale structures. Much of the progress in understanding the physics of galaxy clustering and comparison…
A Modified TreePM Code
Nishikanta Khandai, J. S. Bagla
We discuss the performance characteristics of using the modification of the tree code suggested by Barnes \citep{1990JCoPh..87..161B} in the context of the TreePM code. The optimis…
Gravitational collapse in an expanding background and the role of substructure II: Excess power at small scales and its effect of collapse of structures at larger scales
J. S. Bagla, Jayanti Prasad
We study the interplay of clumping at small scales with the collapse and relaxation of perturbations at larger scales using N-Body simulations. We quantify the effect of collapsed…
Fractal Dimensions of a Weakly Clustered Distribution and the Scale of Homogeneity
J. S. Bagla, Jaswant Yadav, T. R. Seshadri
Homogeneity and isotropy of the universe at sufficiently large scales is a fundamental premise on which modern cosmology is based. Fractal dimensions of matter distribution is a pa…
Gravitational Clustering in Redshift Space: Non-Gaussian Tail of the Cosmological Density Distribution Function
J. S. Bagla, Suryadeep Ray
We study the non-Gaussian tail of the probability distribution function of density in cosmological N-Body simulations for a variety of initial conditions. We compare the behaviour…
Understanding the origin of CMB constraints on Dark Energy
H. K. Jassal, J. S. Bagla, T. Padmanabhan
We study the observational constraints of CMB temperature and polarization anisotropies on models of dark energy, with special focus on models with variation in properties of dark…
Effects of the size of cosmological N-Body simulations on physical quantities -- I: Mass Function
J. S. Bagla, Jayanti Prasad
N-Body simulations are a very important tool in the study of formation of large scale structures. Much of the progress in understanding the physics of galaxy formation and comparis…
Cosmological N-Body Simulations
J. S. Bagla, T. Padmanabhan
In this review we discuss Cosmological N-Body codes with a special emphasis on Particle Mesh codes. We present the mathematical model for each component of N-Body codes. We compare…
Cosmological N-Body simulation: Techniques, Scope and Status
J. S. Bagla
Cosmological N-Body simulations have become an essential tool for studying formation of large scale structure. These simulations are computationally challenging even though the ava…
Comments on the size of the simulation box in cosmological N-Body simulations
J. S. Bagla, Suryadeep Ray
N-Body simulations are a very important tool in the study of formation of large scale structures. Much of the progress in understanding the physics of high redshift universe and co…
Gravitational Collapse in an Expanding Universe: Scaling Relations for Two-Dimensional Collapse Revisited
S. Ray, J. S. Bagla, T. Padmanabhan
We investigate non-linear scaling relations for two-dimensional gravitational collapse in an expanding background using a 2D TreePM code and study the strongly non-linear regime ($…
Gravitational collapse in an expanding background and the role of substructure I: Planar collapse
J. S. Bagla, Jayanti Prasad, Suryadeep Ray
We study the interplay of clumping at small scales with the collapse and relaxation of perturbations at much larger scales. We present results of our analysis when the large scale…
A Parallel TreePM Code
Suryadeep Ray, J. S. Bagla
We present an algorithm for parallelising the TreePM code. We use both functional and domain decompositions. Functional decomposition is used to separate the computation of long ra…
WMAP constraints on low redshift evolution of dark energy
H. K. Jassal, J. S. Bagla, T. Padmanabhan
The conceptual difficulties associated with a cosmological constant have led to the investigation of alternative models in which the equation of state parameter, , of the da…
Prospects for detecting neutral hydrogen using 21cm radiation from large scale structure at high redshifts
J. S. Bagla, Martin White
We estimate the signal from large scale structure at high redshifts in redshifted 21cm line. We focus on z ~ 3 and the LCDM cosmology. We assume that neutral hydrogen is to be foun…
Performance Characteristics of TreePM codes
J. S. Bagla, Suryadeep Ray
We present a detailed analysis of the error budget for the TreePM method for doing cosmological N-Body simulations. It is shown that the choice of filter for splitting the inverse…
A Comparison of Simulated and Analytic Major Merger Counts
J. D. Cohn, J. S. Bagla, Martin White
We use large volume, high resolution, N-body simulations of 3 different CDM models, with different clustering strengths, to generate dark matter halo merging histories. Over the…
TreePM: A code for Cosmological N-Body Simulations
J. S. Bagla
We describe the TreePM method for carrying out large N-Body simulations to study formation and evolution of the large scale structure in the Universe. This method is a combination…
The Observed Evolution of Galaxy Clustering Vs. Epoch-Dependent Biasing Models
M. Magliocchetti, J. S. Bagla, S. J. Maddox +1
We study the observed evolution of galaxy clustering as a function of redshift. We find that the clustering of galaxies decreases as we go from observations of the local Universe t…
Evolution of Galaxy and Quasar Clustering
J. S. Bagla
We study the evolution of correlation function of dark matter halos in the CDM class of models. We show that the halo correlation function does not evolve in proportion with the co…
Gamma-ray bursts from stellar remnants: probing the Universe at high redshift
Ralph A. M. J. Wijers, Joshua S. Bloom, Jasjeet S. Bagla +1
A gamma-ray burst (GRB) releases an amount of energy similar to that of a supernova explosion, which combined with its rapid variability suggests an origin related to neutron stars…
Clustering in Redshift Space at High Redshifts
J. S. Bagla
Recent observations show a large concentration of galaxies at high redshift. At first sight strong clustering of galaxies at high redshifts seems to be in contradiction with the mo…
Critical Index and Fixed Point in the Transfer of Power in Nonlinear Gravitational Clustering
J. S. Bagla, T. Padmanabhan
We investigate the transfer of power between different scales and coupling of modes during non-linear evolution of gravitational clustering in an expanding universe. We start with…