A5101810966- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Remote Sensing in Agriculture
- Vehicle emissions and performance
- Water Quality and Resources Studies
- Stellar, planetary, and galactic studies
- Smart Materials for Construction
- Prosthetics and Rehabilitation Robotics
- Robotic Locomotion and Control
- Magnetic confinement fusion research
- Nuclear reactor physics and engineering
- Biomimetic flight and propulsion mechanisms
- Gamma-ray bursts and supernovae
- 3D Modeling in Geospatial Applications
- Plant Water Relations and Carbon Dynamics
- Geological Modeling and Analysis
- Gaussian Processes and Bayesian Inference
- Underground infrastructure and sustainability
- Laser-Plasma Interactions and Diagnostics
- Ocean Acidification Effects and Responses
- Nuclear Engineering Thermal-Hydraulics
- Dark Matter and Cosmic Phenomena
- Diamond and Carbon-based Materials Research
- Animal Disease Management and Epidemiology
- Zoonotic diseases and public health
Carnegie Mellon University
2018-2025
University of the West Indies System
2024
Yale University
2014-2018
University of Michigan
2011
McGill University
2003-2007
University of Waterloo
2001
RHex is a hexapod with compliant legs and only six actuated degrees of freedom. Its ability to traverse highly fractured unstable terrain, as well ascend descend particular flight stairs has already been documented. In this paper, we describe an open loop controller that enables our small robot (length: 51 cm, width: 20 height: 12.7 leg length: 16 cm) reliably climb wide range regular, full-size no operator input during stair climbing. Experimental data energy efficiency in form specific...
The connection between galaxies and dark matter haloes is often inferred from data using probabilistic models, such as the halo occupation distribution (HOD). Conventional HOD formulations assume that only mass governs galaxy–halo connection. Violations of this assumption, known galaxy assembly bias, threaten programme. We introduce decorated HODs, a new, flexible class models designed to account for bias. Decorated HODs minimally expand parameter space maximize independence traditional...
We present the first stable release of Halotools (v0.2), a community-driven Python package designed to build and test models galaxy-halo connection. provides modular platform for creating mock universes galaxies starting from catalog dark matter halos obtained cosmological simulation. The supports many common forms used describe models: halo occupation distribution (HOD), conditional luminosity function (CLF), abundance matching, alternatives these that include effects such as environmental...
Abstract This paper introduces cosmoDC2, a large synthetic galaxy catalog designed to support precision dark energy science with the Large Synoptic Survey Telescope (LSST). CosmoDC2 is starting point for second data challenge (DC2) carried out by LSST Dark Energy Science Collaboration (LSST DESC). The based on trillion-particle, (4.225 Gpc) 3 box cosmological N -body simulation, Outer Rim run. It covers 440 deg 2 of sky area redshift z = and matches expected number densities from...
We investigate the ability of current implementations galaxy group finders to recover colour-dependent halo occupation statistics. To test fidelity catalogue inferred statistics, we run three different used in literature over a mock that includes colours realistic manner. Overall, resulting catalogues are remarkably similar, and most statistics recovered with reasonable accuracy. However, it is also clear certain systematic errors arise as consequence correlated membership determination,...
We present a detailed study of how dark matter haloes assemble their mass and grow (central) potential well. characterize these via accretion histories (MAHs) well growth (PWGHs), which we extract from the Bolshoi simulation semi-analytical merger trees supplemented with method to compute maximum circular velocity, Vmax, progenitor haloes. The results both methods are in excellent agreement, terms average scatter. show that MAH PWGH tightly correlated, central precedes assembly mass;...
Galaxy clustering on small scales is significantly under-predicted by sub-halo abundance matching (SHAM) models that populate (sub-)haloes with galaxies based peak halo mass, $M_{\rm peak}$. SHAM the maximum circular velocity, $V_{\rm peak}$, have had much better success. The primary reason peak}$ fail relatively low of satellite produced in these compared to those Despite success predicting clustering, a simple model results predictions for galaxy growth are at odds observations. We...
We present the first comprehensive analysis of segregation dark matter subhaloes in their host haloes. Using numerical simulations, we examine twelve different subhalo properties with respect to both orbital energy and halo-centric radius (in real space as well projection). Subhaloes are strongly segregated by accretion redshift, which is an outcome inside-out assembly Since that were accreted earlier have experienced more tidal stripping, lost a larger fraction mass at infall on bound...
Standard approaches to Bayesian parameter inference in large scale structure assume a Gaussian functional form (chi-squared form) for the likelihood. This assumption, detail, cannot be correct. Likelihood free inferences such as Approximate Computation (ABC) relax these restrictions and make possible without making any assumptions on Instead ABC relies forward generative model of data metric measuring distance between data. In this work, we demonstrate that is feasible LSS by using it...
We present the first controller that allows our small hexapod robot, RHex, to descend a wide variety of regular sized, "real world" stairs. After selecting one two sets trajectories, depending on slope stairs, open-loop, clock-driven controllers require no further operator input nor task level feedback. Energetics for stair descent is captured via specific resistance values and compared ascent other behaviors. Even though algorithms developed validated in this paper were particular basic...
Dark matter halo clustering depends not only on mass, but also other properties such as concentration and shape. This phenomenon is known broadly assembly bias. We explore the dependence of bias definition, parametrized by spherical overdensity parameter, $\Delta$. summarize strength concentration-, shape-, spin-dependent a function mass definition. Concentration-dependent strongly at all For conventional definitions ($\Delta \sim 200\mathrm{m}-600\mathrm{m}$), concentration-dependent low...
Most models for the connection between galaxies and their haloes ignore possibility that galaxy properties may be correlated with halo other than mass, a phenomenon known as assembly bias. Yet, it is such correlations can lead to systematic errors in interpretation of survey data. At present, degree which bias present real Universe, best strategies constraining remain uncertain. We study ability several observables constrain from redshift data using decorated occupation distribution (dHOD),...
Abstract We measure the environmental dependence, where environment is defined by distance to third nearest neighbor, of multiple galaxy properties inside Environmental COntext (ECO) catalog. focus primarily on void galaxies, which we define as 10% galaxies having lowest local density. compare and non-void galaxies: baryonic mass, color, fractional stellar mass growth rate (FSMGR), morphology, gas-to-stellar-mass ratio (estimated from a combination H i data photometric gas fractions...
We extend current models of the halo occupation distribution (HOD) to include a flexible, empirical framework for forward modeling intrinsic alignment (IA) galaxies. A primary goal this work is produce mock galaxy catalogs purpose validating existing and methods mitigation IA in weak lensing measurements. This technique can also be used new, simulation-based predictions clustering. Our model probabilistically formulated, rests upon assumption that orientations galaxies exhibit correlation...
Determining the positions of halo centres in large-scale structure surveys is crucial for many cosmological studies. A common assumption that correspond to location their brightest member galaxies. In this paper, we study dynamics galaxies with respect other members Sloan Digital Sky Survey DR7. Specifically, look at line-of-sight velocity and spatial offsets between neighbours. We compare those detailed mock catalogues, constructed from high-resolution, dark-matter-only $N$-body...
The use of high-quality simulated sky catalogs is essential for the success cosmological surveys. have diverse applications, such as investigating signatures fundamental physics in observables, understanding effect systematic uncertainties on measured signals and testing mitigation strategies reducing these uncertainties, aiding analysis pipeline development testing, survey strategy optimization. list applications growing with improvements quality details that they can provide. Given...
As part of the effort to meet needs Large Synoptic Survey Telescope Dark Energy Science Collaboration (LSST DESC) for accurate, realistically complex mock galaxy catalogs, we have developed GalSampler, an open-source python package that assists in generating large volumes synthetic cosmological data. The key idea behind GalSampler is recast hydrodynamical simulations and semi-analytic models as physically-motivated libraries. populates a new, larger-volume halo catalog with galaxies drawn...
Only a small fraction of local galaxies harbor an accreting black hole, classified as active galactic nucleus (AGN). However, many stellar systems are plausibly expected to host holes, from globular clusters nuclear star clusters, massive galaxies. The mere presence stars in the vicinity hole provides source fuel via mass loss evolved stars. In this paper we assess luminosities holes embedded different sizes and properties, spanning large range masses. We model distribution derive amount gas...
We construct halo occupation distribution (HOD) models of high redshift ($z \gtrsim 7.5$) galaxies with $M_{*}>10^8~M_{\odot}/h$ using the BlueTides hydrodynamic simulation suite, a particular emphasis on modelling small scale / 1-halo clustering ($0.01\lesssim r \lesssim 1~ h^{-1}\rm{Mpc}$). Similar to low studies, we find that central and satellite mean HODs ($\left<N_{\mathrm{cen}}\right>$ $\left<N_{\mathrm{sat}}\right>$) can be modeled by smoothed step function power law respectively....
Abstract Life depends on the ocean, with societal health, cultural systems and national economies reliant ocean processes resources. As resources are used, humans continue to drive climate change, benefits from society being diminished. Science must meet needs of policy deliver decision makers information tools for identifying pathways that support continued delivery derives whilst minimising impacts. This is crucial if world’s nations goals targets they have set under international...
ABSTRACT In order to prepare for the upcoming wide-field cosmological surveys, large simulations of Universe with realistic galaxy populations are required. particular, tendency galaxies naturally align towards overdensities, an effect called intrinsic alignments (IA), can be a major source systematics in weak lensing analysis. As details formation and evolution relevant IA cannot simulated practice on such volumes, we propose as alternative Deep Generative Model. This model is trained...