The Andromeda Effect: Dark Matter Halos in a Local Group - - PowerPoint PPT Presentation

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The Andromeda Effect: Dark Matter Halos in a Local Group - - PowerPoint PPT Presentation

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The Andromeda Effect: Dark Matter Halos in a Local Group Configuration with James Bullock, Jose Oorbe, Shea Garrison-Kimmel UC Irvine Mike Boylan-Kolchin, and Kyle Lee Thursday, August 16, 12 The Local Volume Thursday, August 16, 12

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SLIDE 1

The Andromeda Effect: Dark Matter Halos in a Local Group Configuration

Shea Garrison-Kimmel UC Irvine

with James Bullock, Jose Oñorbe,

Mike Boylan-Kolchin, and Kyle Lee

Thursday, August 16, 12

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SLIDE 2

The “Local Volume”

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SLIDE 3

The “Local Volume”

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SLIDE 4

The “Local Volume”

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SLIDE 5

The “Local Volume”

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SLIDE 6

The “Local Volume”

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SLIDE 7

Redefining “Near-Field” Astronomy

SDSS Limit

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SLIDE 8

SDSS Limit Rvir

Redefining “Near-Field” Astronomy

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SLIDE 9

SDSS Limit Rvir

Redefining “Near-Field” Astronomy

LSST

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SLIDE 10

Looking for Local Groups in Simulations

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SLIDE 11

Looking for Local Groups in Simulations

Selected otherwise isolated pairs of halos in thirty-four 70 Mpc Gadget2 runs with:

  • Thursday, August 16, 12
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SLIDE 12

Looking for Local Groups in Simulations

Selected otherwise isolated pairs of halos in thirty-four 70 Mpc Gadget2 runs with:

  • Identified 880 pairs

(find one pair per ~(24 Mpc)3)

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SLIDE 13

Paired Halos: LG Analogues?

Vradial

km/s

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SLIDE 14

Paired Halos: LG Analogues?

Vradial

km/s

n4 Mpc/nbox

Over-density of halos bigger than SMC within 4 Mpc

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SLIDE 15

Paired Halos: LG Analogues?

Vradial

km/s

n4 Mpc/nbox

Over-density of halos bigger than SMC within 4 Mpc

Vtangential

km/s

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SLIDE 16

Paired Halos: LG Analogues?

n4 Mpc/nbox Vradial

km/s Over-density of halos bigger than SMC within 4 Mpc

Vtangential

km/s

Tikhonov & Klypin, 2009 van der Marel et al., 2012

Observed

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SLIDE 17

Paired Halos: LG Analogues?

n4 Mpc/nbox Vradial

km/s Over-density of halos bigger than SMC within 4 Mpc

We find similar distributions in Bolshoi (Klypin et al., 2011)

Vtangential

km/s

Tikhonov & Klypin, 2009 van der Marel et al., 2012

Observed

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SLIDE 18

n4 Mpc/nbox

Paired Halos: LG Analogues?

n4 Mpc/nbox Isolated Halos Paired Halos

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SLIDE 19

Resolution Requirements

Simulating the same halo at four resolutions Vmax N(>Vmax)

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SLIDE 20

Resolution Requirements

Simulating the same halo at four resolutions N(>Vmax)

Resolution Limit

Vmax

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SLIDE 21

The ELVIS Suite:

Exploring the Local Volume In Simulations

  • Twenty-two halos in LG-like configurations
  • Twenty-two mass-matched isolated halos

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SLIDE 22

The ELVIS Suite:

Exploring the Local Volume In Simulations

  • Twenty-two halos in LG-like configurations
  • Twenty-two mass-matched isolated halos
  • Thursday, August 16, 12
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SLIDE 23

The ELVIS Suite:

Exploring the Local Volume In Simulations

  • Twenty-two halos in LG-like configurations
  • Twenty-two mass-matched isolated halos
  • Thursday, August 16, 12
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SLIDE 24

The ELVIS Suite:

Exploring the Local Volume In Simulations

  • Twenty-two halos in LG-like configurations
  • Twenty-two mass-matched isolated halos
  • Up to 15 million particles in a halo

and up to 42 million high-res particles in the uncontaminated region

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SLIDE 25

~1 Mpc

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SLIDE 26

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SLIDE 27

Structure Formation in LG Pairs

z = 0

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SLIDE 28

Structure Formation in LG Pairs

z = 0 z = 7

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SLIDE 29

Vpeak maximum circular velocity over all time

Halos within Rvir

Isolated Sample Paired Sample

Samples agree within the virial radius

Vpeak N(>Vpeak)

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SLIDE 30

Isolated Sample Paired Sample

Halos within Rvir

Samples agree within the virial radius

Vpeak/Vvir N(>Vpeak/Vvir)

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SLIDE 31

Isolated Sample Paired Sample

Halos within 1 Mpc

Vpeak/Vvir N(>Vpeak/Vvir)

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SLIDE 32

1 Mpc

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SLIDE 33

1 Mpc

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SLIDE 34

Isolated Sample Paired Sample

Halos outside MW and M31

~60% more halos in paired environments

Vpeak/Vvir N(>Vpeak/Vvir)

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SLIDE 35
  • New surveys (Pan-STARRS, SkyMapper,

DES, LSST, etc.) are pushing the boundaries

  • f discovery within the Local Group
  • Simulations need to resolve large regions

with a comparable mass halo nearby to confront these data

  • Overdensity of galaxies brighter than SMC

within 4 Mpc isn’t unexpected for halos that live in Local Group configurations

Conclusions

Thursday, August 16, 12

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SLIDE 36
  • ELVIS Suite:
  • Eleven Local Group pairs selected for zoom

simulations from large volume simuations

  • Twenty two mass-matched isolated halos
  • Subhalo number counts within Rvir agree between

isolated and LG zoom simulations

  • LG simulations predict about 150 galaxies larger than

Carina outside Rvir of the MW or M31 but within 1 Mpc, versus only about 90 in isolated simulations

Conclusions

Thursday, August 16, 12