Can we solve the Planes of Satellites Problem by invoking special - - PowerPoint PPT Presentation

Marcel S. Pawlowski

Schwarzschild Fellow at Leibniz-Institute for Astrophysics, Potsdam

✉ marcel.pawlowski@uci.edu @8minutesold

Can we solve the Planes of Satellites Problem by invoking special host halo properties or baryonic effects? 
 


Collaborators: James Bullock, Benoit

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Bonus: Preview of the classical satellite plane of the MW in light of Gaia DR2

• Observed satellite galaxy systems (Milky Way, Andromeda, Centaurus A) are flattened

and show signs of kinematic correlation indicative of co-rotation

• Frequency of as strongly flattened and kinematically coherent satellite systems in ΛCDM

simulations is very low (on order 0.1%).

Planes of Satellite Galaxies

Black ellipse: M31
 Dashed line: orientation of satellite plane
 Contour: PAndAS footprint Obscured by MW disk Obscured by MW disk Larger symbols: LMC & SMC

See review (Pawlowski, 2018)

Pawlowski, Kroupa & Jerjen 
 (2012, MNRAS, 423, 1109) Müller, Pawlowski, Jerjen & Lelli 
 (2018, Science, 359, 534) Ibata et al. 
 (2013, Nature, 493, 62)

240 260 280 300 320 340 360 380

rvir[kpc]

2 4 6 8 10 12 14 16 18

c−2

Fit Prada et al. (2012) 1σ scatter

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

z0.5

Can we solve the Planes of Satellites 
 problem by saying MW/M31 are special?

Buck et. al (2015), based on 21 hosts:

• High host halo concentration (proxy for early

formation) gives more narrow satellite planes.

• Solves problem if MW & M31 formed early and/or

have high concentration halos. We test these findings with a number of improvements:

• 60 (Phat)ELVIS hosts, similar parameter space.
• Compare to randomized satellite systems, too.
• Consider PAndAS survey footprint.
• Employ quantitative tests of correlations.

(“POS” problem?)

"

We employ many different tests to look for correlations … I’ll spare you the details, check out the paper if interested.

Pawlowski, Bullock, Kelley & Famaey; 2019, ApJ, 875, 105

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : PAndAS Positions : Sim

270 285 300 315 330 345 360

rvir

Volume: PAndAS Volume: Rvir

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : Rvir Positions : Rand

270 285 300 315 330 345 360

rvir

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : Rvir Positions : Sim

270 285 300 315 330 345 360

rvir

Correlation with halo mass / viral radius?

Correlation seen if 30 satellites selected from virial volume. ➡Absolute plane width sensitive to overall extent of satellite distribution.

Pawlowski, Bullock, Kelley & Famaey; 2019, ApJ, 875, 105

⬅ thinner satellite plane more satellites in plane fit ➡

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : PAndAS Positions : Sim

270 285 300 315 330 345 360

rvir

Volume: PAndAS Volume: Rvir

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : Rvir Positions : Rand

270 285 300 315 330 345 360

rvir

Correlation with halo mass / viral radius?

Correlation seen if 30 satellites selected from virial volume. ➡Absolute plane width sensitive to overall extent of satellite distribution. ➡Same present in distributions drawn from isotropy. ➡Not a feature of ΛCDM.
 


Pawlowski, Bullock, Kelley & Famaey; 2019, ApJ, 875, 105

⬅ thinner satellite plane more satellites in plane fit ➡

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : PAndAS Positions : Sim

270 285 300 315 330 345 360

rvir

Volume: PAndAS Volume: Rvir

Correlation with halo mass / viral radius?

Correlation seen if 30 satellites selected from virial volume. ➡Absolute plane width sensitive to overall extent of satellite distribution. ➡Same present in distributions drawn from isotropy. ➡Not a feature of ΛCDM.
 
 Need to select satellites from mock- PAndAS volume.

Pawlowski, Bullock, Kelley & Famaey; 2019, ApJ, 875, 105

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : PAndAS Positions : Sim

270 285 300 315 330 345 360

rvir

Volume: PAndAS

Correlation with halo mass / viral radius?

Correlation seen if 30 satellites selected from virial volume. ➡Absolute plane width sensitive to overall extent of satellite distribution. ➡Same present in distributions drawn from isotropy. ➡Not a feature of ΛCDM.
 
 Need to select satellites from mock- PAndAS volume.

Pawlowski, Bullock, Kelley & Famaey; 2019, ApJ, 875, 105

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : PAndAS Positions : Sim

270 285 300 315 330 345 360

rvir

Correlation with halo mass / viral radius?

Correlation seen if 30 satellites selected from virial volume. ➡Absolute plane width sensitive to overall extent of satellite distribution. ➡Same present in distributions drawn from isotropy. ➡Not a feature of ΛCDM.
 
 Need to select satellites from mock- PAndAS volume. Then no correlation with viral mass/radius.

Pawlowski, Bullock, Kelley & Famaey; 2019, ApJ, 875, 105

No

⬅ thinner satellite plane more satellites in plane fit ➡

Correlation with halo concentration / formation time?

No correlation of satellite plane width or kinematic coherence with c-2 or z0.5.

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : Rvir Positions : Sim

2 4 6 8 10 12 14 16

c−2

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : Rvir Positions : Sim

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

z0.5

8 9 10 11 12 13 14 15

NCoorb

10 20 30 40 50 60

min ∆rms[kpc] ELVISall Volume : PAndAS Positions : Sim

2 4 6 8 10 12 14 16

c−2

5 10 15 20 25

NinPlane

10 20 30 40 50 60

min ∆rms[kpc] ELVISall Volume : PAndAS Positions : Sim

2 4 6 8 10 12 14 16

c−2 Observed M31 satellite plane Observed M31 satellite plane

Pawlowski, Bullock, Kelley & Famaey; 2019, ApJ, 875, 105

⬅ thinner satellite plane more satellites in plane fit ➡ ⬅ thinner satellite plane more satellites co-orbit ➡

Correlation with halo concentration / formation time?

No correlation of satellite plane width or kinematic coherence with c-2 or z0.5. Not even if satellites selected from virial volume.

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : Rvir Positions : Sim

2 4 6 8 10 12 14 16

c−2

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : Rvir Positions : Sim

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

z0.5

Pawlowski, Bullock, Kelley & Famaey; 2019, ApJ, 875, 105

⬅ thinner satellite plane more satellites in plane fit ➡

Correlation with halo concentration / formation time?

No correlation of satellite plane width or kinematic coherence with c-2 or z0.5. Not even if satellites selected from virial volume.

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : Rvir Positions : Sim

2 4 6 8 10 12 14 16

c−2

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms[kpc] ELVISall Volume : Rvir Positions : Sim

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

z0.5

We can not confirm results of Buck et al. (2015). Early formation / high concentration of MW/M31 does not solve Planes of Satellites Problem

Pawlowski, Bullock, Kelley & Famaey; 2019, ApJ, 875, 105

No

⬅ thinner satellite plane more satellites in plane fit ➡

⬅ more correlated orbits ⬅ thinner satellite planes

• bserved 


for MW

Correlation with being in a paired configuration of hosts?

No difference whether in a pair of hosts or isolated. Confirms similar result for VPOS-like selection (Pawlowski & McGaugh 2014).

5 10 15 20 25

NinPlane

10 20 30 40 50 60 70 80

min ∆rms [kpc] Environment Volume : PAndAS Positions : Simulation ELVIS isolated ELVIS paired

Pawlowski, Bullock, Kelley & Famaey; 2019, ApJ, 875, 105

No

⬅ thinner satellite plane more satellites in plane fit ➡

PhatELVIS: 12 MW analogs once with and without analytically grown central disk.

Kelley et al. (2019)

Correlation with existence of a central disk galaxy potential?

Pawlowski, Bullock, Kelley & Famaey; 2019, ApJ, 875, 105

PhatELVIS: 12 MW analogs once with and without analytically grown central disk. No differences in flattening of satellite system whether central disk present or not.

Correlation with existence of a central disk galaxy potential?

Pawlowski, Bullock, Kelley & Famaey; 2019, ApJ, 875, 105

8 9 10 11 12 13 14 15

NCoorb

10 20 30 40 50 60 70 80

min ∆rms [kpc] Disk Volume : Rvir Positions : Simulation Phat ELVIS dmo Phat ELVIS disk

5 10 15 20 25 30

NinPlane

20 40 60 80 100 120

min ∆rms [kpc] Disk Volume : Rvir Positions : Simulation Phat ELVIS dmo Phat ELVIS disk

8 9 10 11 12 13 14 15

NCoorb

10 20 30 40 50 60 70 80

min ∆rms [kpc] Disk Volume : PAndAS Positions : Simulation Phat ELVIS dmo Phat ELVIS disk

5 10 15 20 25

NinPlane

10 20 30 40 50 60 70 80

min ∆rms [kpc] Disk Volume : PAndAS Positions : Simulation Phat ELVIS dmo Phat ELVIS disk ⬅ thinner satellite plane more satellites in plane fit ➡ ⬅ thinner satellite plane more satellites co-orbit ➡

PhatELVIS: 12 MW analogs once with and without analytically grown central disk. No differences in flattening of satellite system whether central disk present or not. Also no difference for Centaurus A plane in hydrodynamical Illustris simulation or dark-matter-only analog (Müller, Pawlowski, Lelli & Jerjen, 2018).

Correlation with existence of a central disk galaxy potential?

Pawlowski, Bullock, Kelley & Famaey; 2019, ApJ, 875, 105

No

Summary

We find no indication that width or degree of kinematic coherence of satellite planes correlates with any of the studied host halo properties. The Planes of Satellite Galaxies problem is not solved by claiming an early formation time or high concentration

• f MW/M31 halo, their paired configuration, or baryonic

effects acting on the satellite distribution/orbits.

The orbital alignment of the
 11 classical MW satellites
 with the VPOS
 in light of Gaia DR2

slightly

Orbital Poles (= directions of angular momentum)

Pawlowski et al. in prep.

Orbital poles cluster close to 
 short axis of satellite distribution ➡ many satellites co-orbit along same plane.

Orbital Poles (= directions of angular momentum)

Pawlowski et al. in prep.

Orbital Poles (= directions of angular momentum)

Pawlowski et al. in prep.

Δsph(k) = ∑k

i=1 [arccos (⟨n⟩ ⋅ ni)] 2

k

Measure clustering (circles) with

Evolution of Orbital Pole Clustering

Pawlowski et al. in prep.

2008 2010 2012 2014 2016 2018 2020

year

10 20 30 40 50 60 70

∆std []

k = 3 k = 4 k = 5 k = 6 k = 7 k = 8 k = 9 k = 10 k = 11

Metz et. al. (2008) Pawlowski & Kroupa (2013) This work

Evolution of Orbital Pole Concentrations

As proper motions improved, 
 correlation became more pronounced!

Orbital Pole Concentration vs. Random Velocities

3 4 5 6 7 8 9 10 11

k

20 40 60 80 100

∆sph []

Combined pre Gaia 2018 Gaia DR2 only Random velocities

Highly significant (≥ 99.95%) Shaded regions: 50%, 90%, 99%

Pawlowski et al. in prep.

⬅ more correlated orbits more combined satellites ➡ O b s e r v e d E x p e c t e d f

• r

u n c

• r

r e l a t e d v e l

• c

i t i e s

Orbital Pole Concentration vs. Illustris TNG 100 simulation (hydro & DMO)

3 4 5 6 7 8 9 10 11

k

20 40 60 80 100

∆sph []

Combined pre Gaia 2018 Gaia DR2 only Illustris TNG 100 DMO Randomvelocities 3 4 5 6 7 8 9 10 11

k

20 40 60 80 100

∆sph []

Combined pre Gaia 2018 Gaia DR2 only Illustris TNG 100 Random velocities

Extremely unlikely (≤ 0.05 to 0.5%)

BUT: Must consider orbital pole distribution and spatial flattening ➡ frequencies drop to ≤ 0.1% for all k.

Pawlowski et al. in prep.

⬅ more correlated orbits more combined satellites ➡ ⬅ more correlated orbits more combined satellites ➡

Orbital Pole Concentration vs. Best-Possible Alignment (given satellite positions)

3 4 5 6 7 8 9 10 11

k

20 40 60 80 100

∆sph []

Combined pre Gaia 2018 Gaia DR2 only Closest possible Closest possible median

Assumes: vtan = 175 km/s εPM = 0.05 mas/yr

Pawlowski et al. in prep.

(no errors)

⬅ more correlated orbits more combined satellites ➡

Orbital Pole Concentration vs. Best-Possible Alignment (given satellite positions)

3 4 5 6 7 8 9 10 11

k

20 40 60 80 100

∆sph []

Combined pre Gaia 2018 Gaia DR2 only Closest possible Closest possible median

Assumes: vtan = 175 km/s εPM = 0.05 mas/yr

3 4 5 6 7 8 9 10 11

k

20 40 60 80 100

∆sph []

Combined pre Gaia 2018 Gaia DR2 only Closest possible Closest possible median

Assumes: vtan = 175 km/s εPM = 0.10 mas/yr

Pawlowski et al. in prep.

The 7 most correlated orbital poles are about as closely aligned 
 as geometrically possible!

(no errors)

⬅ more correlated orbits more combined satellites ➡

Conclusions

Review of Satellite Plane Problem ➡ Pawlowski (2018, MPLA, 33, 1830004). The Planes of Satellite Galaxies problem is not solved by claiming an early formation time or high concentration of MW/M31 halo, their paired configuration, or baryonic effects acting on the satellite distribution/orbits. 
 ➡ Pawlowski, Bullock, Kelley & Famaey (2019, ApJ, 875, 105) Gaia DR2 confirms previous work with independent data: 8/11 classical satellites orbit close to common plane. Improved PMs result in tighter clustering of orbital poles (expected if strong underlying correlation). Combining best PMs increases tension with ΛCDM: ≤0.1% of simulated systems as extreme.