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The Dynamical Structure and Ini3al Mass Func3on of the Arches - - PowerPoint PPT Presentation
The Dynamical Structure and Ini3al Mass Func3on of the Arches - - PowerPoint PPT Presentation
The Dynamical Structure and Ini3al Mass Func3on of the Arches Cluster Jessica Lu (UH/IfA), Jay Anderson (StSci), Ma;hew Hosek Jr. Andrea Ghez (UCLA), Mark Morris (UCLA), Will Clarkson (UMichigan-Dearborn), Tuan Do Graduate Student, UH/IfA
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The Arches Cluster: A Young Massive Cluster Near the GalacKc Center
- What impact does the GC
environment have on the dynamical structure of massive star clusters?
~26 pc Arches Cluster GC
Stolte et al. (2008)
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The Arches Cluster: A Young Massive Cluster Near the GalacKc Center
- What impact does the GC
environment have on the dynamical structure of massive star clusters?
- How does the Ini3al Mass
Func3on behave in extreme star- forma3on environments?
~26 pc Arches Cluster GC
Stolte et al. (2008)
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The Arches Cluster: A Young Massive Cluster Near the GalacKc Center
- What impact does the GC
environment have on the dynamical structure of massive star clusters?
- How does the Ini3al Mass
Func3on behave in extreme star- forma3on environments?
~26 pc Arches Cluster GC
Stolte et al. (2008)
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Hosek et al. (2015): Measure the Radial Profile to Large Radii
- Unknown Kdal radius, profile
- nly measured to R = 0.4 pc
(Espinoza+09)
– Extra-Kdal stars?
rt?
1 pc HST WFC3IR image of the Arches Cluster
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Hosek et al. (2015): Measure the Radial Profile to Large Radii
- Unknown Kdal radius, profile
- nly measured to R = 0.4 pc
(Espinoza+09)
– Extra-Kdal stars?
- Challenge: Significant
differenKal reddening
– ΔAV ~ 10-15 mag (Habibi+13) – Cluster membership tricky! 1 pc HST WFC3IR image of the Arches Cluster High reddening Low reddening
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SoluKon: HST Astrometry
- HST WFC3IR: 3 epochs / 2 years in F153M, 1 epoch in F127M
hgp://www.spacetelescope.org/
(1) Proper moKons for improved cluster membership (2) Wide field of view: 120x120’’ (4.8 pc x 4.8 pc) (3) Deep: ~2.5 M
Advantages:
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High-Precision Proper MoKons
~2.5 M 0.65 mas/yr 24.7 km/s Hosek+15
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High-Precision Proper MoKons
~2.5 M 0.65 mas/yr 24.7 km/s Hosek+15
Stars passing error cut: 6023
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Modeling Cluster and Field KinemaKcs: Gaussian Mixture Model
Cluster Vector Point Diagram
Hosek+15
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Modeling Cluster and Field KinemaKcs: Gaussian Mixture Model
Cluster Vector Point Diagram Observed CMD
Hosek+15
Probable Cluster Members (P > 0.7)
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Modeling Cluster and Field KinemaKcs: Gaussian Mixture Model
Cluster Vector Point Diagram
- Diff. De-reddened CMD
Hosek+15
Probable Cluster Members (P > 0.7)
2.5 Myr isochrone
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The Extended Radial Profile of the Arches Cluster
Model: Power-Law + Constant Best-Fit Params: Γ = 2.06 ± 0.17 b = 2.52 ± 1.32 stars/pc2 A0 = 23.09 ± 3.5 stars
Field ContaminaKon: 2.52 stars/pc2
Background subtracted profile: 0.25 pc ≤ R ≤ 3 pc Hosek+15
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The Extended Radial Profile of the Arches Cluster
Model: Power-Law + Constant Best-Fit Params: Γ = 2.06 ± 0.17 b = 2.52 ± 1.32 stars/pc2 A0 = 23.09 ± 3.5 stars
Field ContaminaKon: 2.52 stars/pc2
Background subtracted profile: 0.25 pc ≤ R ≤ 3 pc Background subtracted profile: 0.25 pc ≤ R ≤ 3 pc Espinoza+09: R ≤ 0.4 pc Hosek+15
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The Extended Radial Profile of the Arches Cluster
Model: Power-Law + Constant Best-Fit Params: Γ = 2.06 ± 0.17 b = 2.52 ± 1.32 stars/pc2 A0 = 23.09 ± 3.5 stars
Field ContaminaKon: 2.52 stars/pc2
Background subtracted profile: 0.25 pc ≤ R ≤ 3 pc Background subtracted profile: 0.25 pc ≤ R ≤ 3 pc Espinoza+09: R ≤ 0.4 pc Background subtracted profile: 0.25 pc ≤ R ≤ 3 pc Espinoza+09: R ≤ 0.4 pc
Predicted Tidal Radius: 2.5 pc
3σ lower limit on 3dal radius: 2.8 pc
Hosek+15
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Mass SegregaKon Throughout Cluster
- KS test: not drawn from same parent populaKon
– Stolte+05, Espinoza+09, Habibi+13
17 < F153M < 20 F153M < 17 Γ = 1.75 Γ = 2.70
Hosek+15
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No Evidence of Tidal Tails
Parallel to Orbit Perpendicular to Orbit Γ = 1.86 Γ = 2.32
- KS test: cannot discount same parent populaKon
Hosek+15
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Unbroken Profile: ImplicaKons for Orbital History?
- Fig. 2 of Peñarrubia+09
Peñarrubia+09, Lokas+13: SimulaKons of dwarf galaxies on ellipKcal orbits show break in profile aser pericenter
- PosiKon of break related
to Kme since pericenter passage
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If Applicable to Arches…
- No pericenter passage between ~0.2 – 1 Myr ago
Possible Arches Orbits (Stolte+08)
Data courtesy of Andrea Stolte
Black: Prograde Red: Retrograde
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If Applicable to Arches…
- No pericenter passage between ~0.2 – 1 Myr ago
Possible Arches Orbits (Stolte+08)
Data courtesy of Andrea Stolte
Black: Prograde Red: Retrograde NOT ALLOWED Prograde Retrograde
- Retrograde orbits
excluded
- Arches located in front
- f GC sky plane
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Next Step: Combine HST with AO Data
HST/WFC3IR F153M
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Next Step: Combine HST with AO Data
Keck/NIRC2 AO K’-band Start of Keck/NIRC2 JHK’
- bserving campaign:
2006 HST/WFC3IR F153M
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Conclusions
- HST WFC3IR study of Arches cluster
– Proper moKons to idenKfy cluster members – Large FOV to measure radial profile to 3 pc – Depth: 2.5 M
- Unbroken power-law profile
– 3σ limit on King-like Kdal radius: 2.8 pc – Constrains orbit to prograde soluKons?
- No evidence for Kdal tails
- Next step: Combine HST with