scholarly journals Climbing halo merger trees with TreeFrog

2019 ◽  
Vol 36 ◽  
Author(s):  
Pascal J. Elahi ◽  
Rhys J. J. Poulton ◽  
Rodrigo J. Tobar ◽  
Rodrigo Cañas ◽  
Claudia del P. Lagos ◽  
...  
Keyword(s):  
Binding Energy ◽  
Merit Function ◽  
Massively Parallel ◽  
Mass Ratio ◽  
Ratio Dependence ◽  
Data Products ◽  
Accretion Rates ◽  
Dynamical Time ◽  
Radial Moments

AbstractWe present TreeFrog, a massively parallel halo merger tree builder that is capable comparing different halo catalogues and producing halo merger trees. The code is written in c++11, use the MPI and OpenMP API’s for parallelisation, and includes python tools to read/manipulate the data products produced. The code correlates binding energy sorted particle ID lists between halo catalogues, determining optimal descendant/progenitor matches using multiple snapshots, a merit function that maximises the number of shared particles using pseudo-radial moments, and a scheme for correcting halo merger tree pathologies. Focusing on VELOCIraptor catalogues for this work, we demonstrate how searching multiple snapshots spanning a dynamical time significantly reduces the number of stranded halos, those lacking a descendant or a progenitor, critically correcting poorly resolved halos. We present a new merit function that improves the distinction between primary and secondary progenitors, reducing tree pathologies. We find FOF accretion rates and merger rates show similar mass ratio dependence. The model merger rates from Poole, et al. [2017, 472, 3659] agree with the measured net growth of halos through mergers.

scholarly journals Probing gas disc physics with LISA: simulations of an intermediate mass ratio inspiral in an accretion disc

2019 ◽  
Vol 486 (2) ◽  
pp. 2754-2765 ◽  
Author(s):  
A M Derdzinski ◽  
D D’Orazio ◽  
P Duffell ◽  
Z Haiman ◽  
A MacFadyen
Keyword(s):  
Small Deviation ◽  
Compact Object ◽  
Accretion Disc ◽  
Mass Ratio ◽  
Intermediate Mass ◽  
Laser Interferometer Space Antenna ◽  
Total Phase ◽  
Accretion Rates ◽  
Hydrodynamical Simulations ◽  
And Migration

Abstract The coalescence of a compact object with a $10^{4}\hbox{--}10^{7}\, {\rm M_\odot }$ supermassive black hole (SMBH) produces mHz gravitational waves (GWs) detectable by the future Laser Interferometer Space Antenna (LISA). If such an inspiral occurs in the accretion disc of an active galactic nucleus (AGN), the gas torques imprint a small deviation in the GW waveform. Here, we present two-dimensional hydrodynamical simulations with the moving-mesh code disco of a BH inspiraling at the GW rate in a binary system with a mass ratio q = M2/M1 = 10−3, embedded in an accretion disc. We assume a locally isothermal equation of state for the gas (with Mach number $\mathcal {M}=20$) and implement a standard α-prescription for its viscosity (with α = 0.03). We find disc torques on the binary that are weaker than in previous semi-analytic toy models, and are in the opposite direction: the gas disc slows down, rather than speeds up the inspiral. We compute the resulting deviations in the GW waveform, which scale linearly with the mass of the disc. The SNR of these deviations accumulates mostly at high frequencies, and becomes detectable in a 5 yr LISA observation if the total phase shift exceeds a few radians. We find that this occurs if the disc surface density exceeds $\Sigma _0 \gtrsim 10^{2-3}\rm g\, cm^{-2}$, as may be the case in thin discs with near-Eddington accretion rates. Since the characteristic imprint on the GW signal is strongly dependent on disc parameters, a LISA detection of an intermediate mass ratio inspiral would probe the physics of AGN discs and migration.

STABILITY OF AN EXCITON BOUND TO AN IONIZED ACCEPTOR IN QUANTUM DOTS

2003 ◽  
Vol 17 (11) ◽  
pp. 2273-2279 ◽  
Author(s):  
S. BASKOUTAS ◽  
A. F. TERZIS ◽  
C. POLITIS
Keyword(s):  
Quantum Dots ◽  
Binding Energy ◽  
Quantum Dot ◽  
Numerical Method ◽  
Schrodinger Equation ◽  
Critical Radius ◽  
Critical Value ◽  
Two Dimensional ◽  
Mass Ratio ◽  
Acceptor Impurity

Binding energy for an exciton (X) bound in a parabolic two-dimensional quantum dot by an acceptor impurity A- located on the z-axis at a distance d from the dot plane, are calculated using the Hartree formalism with a recently developed numerical method (PMM) for the solution of the Schrödinger equation. As our analysis indicates there is a critical dot radius Rc such that for R < Rc the complex (A-, X) is unstable and with an increase of the impurity distance this critical radius increases. Furthermore, there is a critical value σc of the mass ratio [Formula: see text] such that for σ > σc the complex is stable.

Aspect and mass ratio dependence of microwave heating in silicon carbide fibers at 2.45 GHz

2018 ◽  
Vol 123 (21) ◽  
pp. 215108 ◽  
Author(s):  
K. Kashimura ◽  
T. Namioka ◽  
T. Fujii ◽  
N. Yoshikawa ◽  
H. Fukushima
Keyword(s):  
Silicon Carbide ◽  
Microwave Heating ◽  
Mass Ratio ◽  
Ratio Dependence ◽  
Silicon Carbide Fibers

scholarly journals Massively Parallel Simulations of Binary Black Hole Intermediate-Mass-Ratio Inspirals

2019 ◽  
Vol 41 (2) ◽  
pp. C97-C138 ◽  
Author(s):  
Milinda Fernando ◽  
David Neilsen ◽  
Hyun Lim ◽  
Eric Hirschmann ◽  
Hari Sundar
Keyword(s):  
Black Hole ◽  
Massively Parallel ◽  
Mass Ratio ◽  
Intermediate Mass ◽  
Parallel Simulations ◽  
Binary Black Hole

scholarly journals Probing shock geometry via the charge to mass ratio dependence of heavy ion spectra from multiple spacecraft observations of the 2013 November 4 event

2016 ◽  
Vol 16 (12) ◽  
pp. 190 ◽  
Author(s):  
Lulu Zhao ◽  
Gang Li ◽  
Glenn M. Mason ◽  
Christina Cohen ◽  
Richard Mewaldt ◽  
...  
Keyword(s):  
Heavy Ion ◽  
Mass Ratio ◽  
Ratio Dependence ◽  
Multiple Spacecraft

scholarly journals A Possible Destruction of SARS-CoV-2 by a Cylindrical Probe Coated with the Graphene Oxide: A Thermal-based Model

2021 ◽  
Vol 11 (5) ◽  
pp. 12706-12716
Keyword(s):  
Molecular Weight ◽  
Graphene Oxide ◽  
Molecular Docking ◽  
Binding Energy ◽  
Mass Ratio ◽  
Cylindrical Probe ◽  
Geometry Model ◽  
Docking Approach ◽  
Set Up ◽  
Maximum Limit

In this paper, the possible use of graphene oxide (GO) to destroy SARS-CoV-2 of COVID-19 is modeled. A molecular docking approach was first conducted to estimate the binding energy of GO with the spike glycoprotein of SARS-CoV-2 virus (SGCoV). A simple space-limited geometry model is used to set up the maximum limit of SARS-CoV-2 that can be absorbed on the GO surface. Using the GO surface as a hotbed for virus destruction and utilizing the unique properties of GO (the molecular weight, the area to mass ratio, and the specific heat), we build a thermal-based model to explore the possibility of destroying the adsorbed SARS-CoV-2 on the GO-coated cylindrical probe. A hypothetical design of a medical device that could benefit from this model is also proposed here.

scholarly journals Biexciton binding energy in spherical quantum dots with Gamma-=SUB=-8-=/SUB=- valence band

2018 ◽  
Vol 52 (5) ◽  
pp. 496
Author(s):  
A.A. Golovatenko ◽  
M.A. Semina ◽  
A.V. Rodina ◽  
T.V. Shubina
Keyword(s):  
Quantum Dots ◽  
Perturbation Theory ◽  
Binding Energy ◽  
Heavy Hole ◽  
Energy Gap ◽  
Mass Ratio ◽  
Small Energy ◽  
First Order ◽  
Biexciton Binding Energy ◽  
First Order Perturbation

AbstractThe biexciton binding energy in spherical CdSe/ZnSe quantum dots is calculated variationally in the framework of kp-perturbation theory. Smooth and abrupt confining potentials with the same localization area of carriers are compared for two limiting cases of light hole to heavy hole mass ratio β = m_ lh /m_ hh : β = 1 and β = 0. Accounting for correlations between carriers results in their polarized configuration and significantly increases the biexciton binding energy in comparison with the first order perturbation theory. For β = 0 in smooth confining potentials there are three nearby biexciton states separated by small energy gap between 1 S _3/2 and 1 P _3/2 hole states.

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