The Role Of Globular Clusters During ReionizationGlobular Cluster Primer Dense stellar systems...
Transcript of The Role Of Globular Clusters During ReionizationGlobular Cluster Primer Dense stellar systems...
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The Role Of Globular Clusters During Reionization
Brendan GriffenMKI Level 5, Room 582K
Friday, 26 April 13
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Collaboration
Michael Drinkwater
Ilian Iliev
PeterThomas
GarreltMellema
Brendan Griffen
University of Queensland University of Sussex
University of Stockholm
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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
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Background
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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
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Globular Cluster PrimerTwo populations: metal-rich & metal-poor
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-1.59 -0.59
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Formation ScenariosMajor Mergers
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Antennae Galaxies
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Formation ScenariosHierarchical
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t = 13 Gyrs
t = 0
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Relation To ReionizationMajority formed between ~10-14 Gyrs ago
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Forbes & Bridges (2010)
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Relation To ReionizationAge consistent with reionization epoch
Barkana & Loeb (2007)
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Metal Poor GC
Formation
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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
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Schaerer & Charbonnel (2011)
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Previous WorkModelled formation but not contribution to reionization
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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
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The Aquarius Suite~2000 particles per cluster
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Identifying Formation SitesCooling is most efficient at T~104 K
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Coo
ling
Rat
e [e
rg c
m^3
/sec
]
Temperature [K]Loeb (2010)
atomic cooling
molecular cooling
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Identifying Formation Sites
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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.
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The Radiative Transfer Code
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The Radiative Transfer CodeWell tested against other codes
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The Radiative Transfer CodeRay tracing naturally treats inhomogeneities correctly
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Range Of EfficienciesPhysically motivated from literature
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--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
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0246810121416182022240
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mb
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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)
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Resultsz = 0 radial distributions
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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)
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ResultsContribution To Local Reionization
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z = 13
fγ
xv
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z = 7
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Results Contribution To Local Reionization (within 23 h-3 Mpc3)
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05101520250
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Mas
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Frac
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Model Extensions Dynamical Disruption
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Model Extensions Dynamical Disruption
galaxy rotation velocity
galactocentric radius
scaling parameter orbital eccentricity
mass of cluster
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Baumgardt & Makino (2003)
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Results The effect of disruption
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60% of all primordial GCs are destroyed through dynamical disruption alone
0 20 40 60 80 100 120 1400
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mb
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R/kpc0 20 40 60 80 100 120 140
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R)
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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)
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Future Work
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Spitler et al. (2012)
Millennium-II simulation
“Num
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CaterPillar ProjectBeing carried out on level 5/6
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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
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Sim
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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
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