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HALO FINDING INENZO, ART, AND GADGET
Peter Behroozi, Stanford UniversityUC-HIPACC Summer School 2010
Friday, August 13, 2010
HALO FINDING IN ENZO
Peter Behroozi, Stanford UniversityUC-HIPACC Summer School 2010
Actually, mostly just:
Friday, August 13, 2010
The Simulation128 cubed root mesh, 60 Mpc/h, WMAP5 cosmology
Circles represent halo maximum radiiFriday, August 13, 2010
Halo Finding Algorithms Bundled with ENZO
Friday, August 13, 2010
Halo Finding Algorithms Bundled with ENZO
HOP / Parallel HOP(particles attached to same halo as the densest
particle in their N nearest neighbors)
Friday, August 13, 2010
Halo Finding Algorithms Bundled with ENZO
HOP / Parallel HOP(particles attached to same halo as the densest
particle in their N nearest neighbors)
FOF / SUBFIND(particles attached to same halo as their nearest
neighbors within a specified linking length)
Friday, August 13, 2010
Which one is better?
HOP / Parallel HOP(particles attached to same halo as the densest
particle in their N nearest neighbors)
FOF / SUBFIND(particles attached to same halo as their nearest
neighbors within a specified linking length)
Friday, August 13, 2010
Quantitative Tests
Friday, August 13, 2010
Quantitative Tests
How consistent are halo positionsand velocities from onetimestep to the next?
Friday, August 13, 2010
Quantitative Tests
How consistently can the growth ofstructure be traced from the
halo catalogs?
How consistent are halo positionsand velocities from onetimestep to the next?
Friday, August 13, 2010
Quantitative TestsAll tests performed using a new gravitational
consistency code under development for repairingmerger trees and halo catalogs.
F =GM1M2
r2 + r2vir
dF
dr=
2GM1M2
r3> Tmin
Gravitational Acceleration
Tidal Merger Criterion
Friday, August 13, 2010
Quantitative Results
Friday, August 13, 2010
Quantitative ResultsPositional Consistency:
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Scale Factor
0
0.1
0.2
0.3
0.4
0.5
Avg
. Pos
ition
al E
rror
in H
alo
Trac
king
(Cm
vng
Mpc
/h)
M ~ 1011.25
M ~ 1012
M ~ 1013
M ~ 1014
How robust are halo properties?
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Scale Factor
0.1
0.2
0.3
0.4
0.5
Avg
. Pos
ition
al E
rror
in H
alo
Trac
king
(Cm
vng
Mpc
/h)
M ~ 1011.25
M ~ 1012
M ~ 1013
M ~ 1014
(Force resolution of simulation: 15 kpc/h)
Friday, August 13, 2010
Quantitative ResultsInertial Consistency:
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Scale Factor
0
40
80
120
160
200
240
280
Avg
. Vel
ocity
Err
or in
Hal
o Tr
acki
ng (k
m/s
)
M ~ 1011.25
M ~ 1012
M ~ 1013
M ~ 1014
How robust are halo properties?
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Scale Factor
0
40
80
120
160
200
240
280
Avg
. Vel
ocity
Err
or in
Hal
o Tr
acki
ng (k
m/s
)
M ~ 1011.25
M ~ 1012
M ~ 1013
M ~ 1014
Friday, August 13, 2010
Quantitative ResultsFraction of halos missing at the previous timestep:
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Scale Factor
0
0.1
0.2
0.3
Frac
tion
of H
alos
With
out P
roge
nito
rs
M ~ 1011
M ~ 1012
M ~ 1013
M ~ 1014
How useful are the catalogs for merger trees?
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Scale Factor
0
0.1
0.2
0.3
Frac
tion
of H
alos
With
out P
roge
nito
rs
M ~ 1011
M ~ 1012
M ~ 1013
M ~ 1014
Friday, August 13, 2010
Quantitative ResultsFraction of halos missing at the next timestep:
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Scale Factor
0
0.1
0.2
0.3
Frac
tion
of H
alos
Rem
aini
ng W
ithou
t Des
cend
ants
M ~ 1011
M ~ 1012
M ~ 1013
M ~ 1014
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Scale Factor
0
0.1
0.2
0.3
Frac
tion
of H
alos
Rem
aini
ng W
ithou
t Des
cend
ants
M ~ 1011
M ~ 1012
M ~ 1013
M ~ 1014
How useful are the catalogs for merger trees?
Friday, August 13, 2010
Quantitative Results
Side note: Increased Resolution Helps a Great Deal!
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Scale Factor
0
0.01
0.02
Frac
tion
of H
alos
Rem
aini
ng W
ithou
t Des
cend
ants
M ~ 1010
M ~ 1011
M ~ 1012
M ~ 1013
M ~ 1014
(Bolshoi)
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Scale Factor
0
0.01
0.02
0.03
0.04
Frac
tion
of H
alos
Rem
aini
ng W
ithou
t Des
cend
ants
M ~ 1011
M ~ 1012
M ~ 1013
M ~ 1014
(Consuelo)
(GADGET-2) (ART)(2.7 billion particles) (8.6 billion particles) (1400 particles)
Fraction of halos missing at the next timestep
Friday, August 13, 2010
Halo Finders in Action!
Friday, August 13, 2010
Thanks for your attention!Peter Behroozi
Friday, August 13, 2010
Quantitative ResultsHalo Tracking Consistency
1 2 3 4 51+z
0.01
0.1
1
Frac
tion
of H
alos
Tra
cked
Vmax ~ 100 km/sVmax ~ 200 km/sVmax ~ 400 km/sVmax ~ 800 km/s
1 2 3 4 5 61+z
0.01
0.1
1
Frac
tion
of H
alos
Tra
cked
Vmax ~ 100 km/sVmax ~ 200 km/sVmax ~ 400 km/sVmax ~ 800 km/s
Friday, August 13, 2010
Image Credits
http://www.elcivics.com/easter_esl_holidays_3
http://www.myfreewallpapers.net/
vehicles/pages/submarine.shtml
http://farm4.static.flickr.com/3172/2297142898_8fae4627e7_
o.jpg
http://embryology.med.unsw.edu.a
u/wwwhuman/Stages/Images/Cst800.jpg
http://www.virtualmuseum.ca/Exhibitions/Annodomini/
THEME_15/IMAGES/J991825.jpg
Friday, August 13, 2010
![Aritmética Elemental [Enzo R Gentile]](https://img.pdfslide.us/doc/110x75/55cf9904550346d0339b0fc8/aritmetica-elemental-enzo-r-gentile.jpg)
