The Role Of Globular Clusters During Reionization Brendan Griffen MKI Level 5, Room 582K Friday, 26 April 13
The Role Of Globular Clusters During Reionization
Brendan GriffenMKI Level 5, Room 582K
Friday, 26 April 13
Collaboration
Michael Drinkwater
Ilian Iliev
PeterThomas
GarreltMellema
Brendan Griffen
University of Queensland University of Sussex
University of Stockholm
Friday, 26 April 13
Outline• What do we know about globular clusters and their formation?
• What is their relationship to reionization?
• Previous numerical work
Background
My Work
Summary
• Identify formation sites & modelling them as sources
• Take home message: Globular clusters are important contributors!
• Extensions: dynamical disruption
Brendan GriffenFriday, 26 April 13
Background
Friday, 26 April 13
Globular Cluster PrimerDense stellar systems
Consist of 104 - 106 stars
Very, very, very old ~ 13 Gyrs
Located in bulge and halo
Milky Way N ~160
BulgeDisk This room
10 kpc
Brendan GriffenFriday, 26 April 13
Globular Cluster PrimerTwo populations: metal-rich & metal-poor
Brendan Griffen
-1.59 -0.59
Friday, 26 April 13
Formation ScenariosMajor Mergers
Brendan Griffen
Antennae Galaxies
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Formation ScenariosHierarchical
Brendan Griffen
t = 13 Gyrs
t = 0
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Relation To ReionizationMajority formed between ~10-14 Gyrs ago
Brendan Griffen
Forbes & Bridges (2010)
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Relation To ReionizationAge consistent with reionization epoch
Barkana & Loeb (2007)
Brendan Griffen
Metal Poor GC
Formation
Friday, 26 April 13
Relation To ReionizationEvidence that metal-poor GCs trace reionization epoch
Brendan GriffenSpitler et al. (2012)
“Num
ber
Den
sity
”
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Relation To ReionizationPotential to produce high numbers of ionising photons
Brendan Griffen
Schaerer & Charbonnel (2011)
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Previous WorkModelled formation but not contribution to reionization
Brendan Griffen
Bekki et al. (2003, 2008) Kravtsov & Gnedin (2005)
~20 particles per GCsensitive to halo finder
~100 particles per GConly evolved to z = 3
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My Work
Friday, 26 April 13
The Aquarius Suite~2000 particles per cluster
Brendan GriffenFriday, 26 April 13
Identifying Formation SitesCooling is most efficient at T~104 K
Brendan Griffen
Coo
ling
Rat
e [e
rg c
m^3
/sec
]
Temperature [K]Loeb (2010)
atomic cooling
molecular cooling
Friday, 26 April 13
Identifying Formation Sites
Brendan Griffen
Assuming dark matter is in equilibrium with the gas, we can use the velocity dispersion to infer a temperature.
We tag all dark matter objects that go above this velocity dispersion threshold.
Friday, 26 April 13
The Radiative Transfer Code
Brendan GriffenFriday, 26 April 13
The Radiative Transfer CodeWell tested against other codes
Brendan GriffenFriday, 26 April 13
The Radiative Transfer CodeRay tracing naturally treats inhomogeneities correctly
Brendan GriffenFriday, 26 April 13
Range Of EfficienciesPhysically motivated from literature
Brendan Griffen
--Tumlinson et al. (2004)--Baumgardt & Makino (2007)--Yajima et al. (2011) Ferrara & Loeb (2011) Wise & Cen (2009)
escape fraction
# photons per baryon
star formation efficiency
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Photon-Richest
Photon-Poorest
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Results In-homgeneous Ionization
Brendan Griffen
0246810121416182022240
5
10
15
20
25
30
35
40
Nu
mb
er
redshift
M1_512_ph150 M1_512_ph250 M1_512_ph500 M1_512_ph700 M1_512_ph1000 M1_512_ph5000 potential sources
60% suppression
85% suppression
Griffen+ (2013)
Friday, 26 April 13
Resultsz = 0 radial distributions
Brendan Griffen
0 20 40 60 80 100 120 1400
20
40
60
80
100
120
Nu
mb
er
R/kpc
M1_512_ph150 M1_512_ph250 M1_512_ph500 M1_512_ph700 M1_512_ph1000 M1_512_ph5000 truncated at z = 13 Milky Way GCs [Fe/H] < −1
Shallow when compared to Milky Way metal-poor GC distributionGriffen+ (2013)
Friday, 26 April 13
ResultsContribution To Local Reionization
Brendan Griffen
150250
500700
10005000 1
23
45
6
0
0.25
0.5
0.75
1
box width
[h−1 Mpc]
z = 13
fγ
xv
150250
500700
10005000 1
23
45
6
0
0.25
0.5
0.75
1
box width
[h−1 Mpc]fγ
xm
150250
500700
10005000 1
23
45
6
0
0.25
0.5
0.75
1
box width
[h−1 Mpc]
z = 10
fγ
xv
150250
500700
10005000 1
23
45
6
0
0.25
0.5
0.75
1
box width
[h−1 Mpc]fγ
xm
150250
500700
10005000 1
23
45
6
0
0.25
0.5
0.75
1
box width
[h−1 Mpc]
z = 7
fγ
xv
150250
500700
10005000 1
23
45
6
0
0.25
0.5
0.75
1
box width
[h−1 Mpc]fγ
xm
Griffen+ (2013)
Friday, 26 April 13
Results Contribution To Local Reionization (within 23 h-3 Mpc3)
Brendan Griffen
05101520250
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
redshift
xv
M1_512_ph150 M1_512_ph250 M1_512_ph500 M1_512_ph700 M1_512_ph1000 M1_512_ph5000
05101520250
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
redshift
xm
M1_512_ph150 M1_512_ph250 M1_512_ph500 M1_512_ph700 M1_512_ph1000 M1_512_ph5000
Mas
s Fr
actio
n
Volu
me
Frac
tion
Griffen+ (2013)
Friday, 26 April 13
Model Extensions Dynamical Disruption
Brendan GriffenFriday, 26 April 13
Model Extensions Dynamical Disruption
galaxy rotation velocity
galactocentric radius
scaling parameter orbital eccentricity
mass of cluster
Brendan Griffen
Baumgardt & Makino (2003)
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Results The effect of disruption
Brendan Griffen
60% of all primordial GCs are destroyed through dynamical disruption alone
0 20 40 60 80 100 120 1400
20
40
60
80
100
120
Nu
mb
er
R/kpc0 20 40 60 80 100 120 140
0
0.2
0.4
0.6
0.8
1
f (<
R)
R/kpc
M1_512_ph150 surv. M1_512_ph150 total M1_512_ph250 surv. M1_512_ph250 total M1_512_ph500 surv. M1_512_ph500 total M1_512_ph700 surv. M1_512_ph700 total M1_512_ph1000 surv. M1_512_ph1000 total M1_512_ph5000 surv. M1_512_ph5000 total Milky Way GCs [Fe/H] < −1
Griffen+ (2013)
Friday, 26 April 13
Future Work
Brendan Griffen
Spitler et al. (2012)
Millennium-II simulation
“Num
ber
Den
sity
”
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CaterPillar ProjectBeing carried out on level 5/6
Brendan Griffen
Team: Greg Dooley
Alex Ji Phillip ZukinAnna Frebel
Ed Bertschinger
Status:Parent simulation complete
Selecting 60+ Milky Way sized halos
First halo at high resolutionto be completed soon
Avalanche of data to follow...
100
Mpc
/hPa
rent
Sim
ulat
ion
Friday, 26 April 13
Brendan Griffen
• Metal-poor globular clusters formed within small dark matter halos
• Age, stellar properties make them ideal candidates for reionization.
• Combined high-resolution dark matter simulation with radiative transfer.
Model
Take Home Message
• Metal-poor globular clusters are candidate contributors to reionization.
• MPGCs contributed ~50% of ionised mass and volume by z = 10.
• Improve: test against a variety environments + include baryons.
• Characterising their contributions is within reach of JWST.
Summary
Friday, 26 April 13