ZOMG: Does the halo assembly history influence central galaxies and - - PowerPoint PPT Presentation

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ZOMG: Does the halo assembly history influence central galaxies and - - PowerPoint PPT Presentation

Jun 19, 2023 441 likes •672 views

ZOMG: Does the halo assembly history influence central galaxies and gas accretion? Emilio Romano-Diaz Enrico Garaldi Mikolaj Borzyszkowski Cristiano Porciani Malta The role of gas in galaxy dynamics October 2 - 6 1 Halo assembly bias 2pt

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SLIDE 1

Does the halo assembly history influence central galaxies and gas accretion?

Emilio Romano-Diaz Enrico Garaldi Mikolaj Borzyszkowski Cristiano Porciani

1

ZOMG:

The role of gas in galaxy dynamics Malta October 2 - 6

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SLIDE 2

Halo assembly bias

  • Nbody simulations have shown that the

clustering of halos of fixed mass varies with halo formation time, concentration and substructure occupation (Sheth &

Tormen 04; Gao +05; Gao & White 07; Jing +07; Harker +06; Wechsler +06; Wetzel +07…)

  • Old haloes reside in dense environments,

younger ones in less dense regions.

  • This effect is stronger at lower masses

and absent at high masses

(Gao, Springel & White 05)

2pt correlation function —> halo clustering

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SLIDE 3

Does the presence of halo assembly bias implies whether also “galaxy assembly bias” exists? In other words, to what extent the assembly history of the host haloes influences galaxy properties and imprints detectable signatures in the galaxy-clustering pattern? (e.g. Jung, Lee & Yi 2014; Hearin,

Watson & van den Bosch 2015; Hearin et al. 2016; Lin et al. 2016, Henriques et al. 2015)

Does the gas follows the same behaviour as DM during accretion?

ZOMG project

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SLIDE 4

ZOMG Project:
 Zooming On a Mob of Galaxies

  • 1. Dark Matter Haloes, assembly bias: Borzyszkowski et al. 2017




  • 2. Galaxy formation, gas accretion: Romano-Diaz et al. 2017
  • 3. Substructure evolution: Garaldi et al. 2017
  • 4. …
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SLIDE 5

ZOMG Project:
 Zooming On a Mob of Galaxies

(Oxford living Dictionary)

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SLIDE 6

ZOMG! Simulations

  • GADGET3, Zoom-in simulations, Planck Cosmology,
  • 7 haloes (DM-only) hosting present-day L* galaxies,

Mh~5x1011M☉ (Borzyszkowski+17) I. Sampling rate 20Myr => detailed assembly history

  • II. 2 haloes collapsed z ~ 0 (accreting)
  • III. 5 haloes collapsed z ~ 1.5 (stalled)
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SLIDE 7

ZOMG! Simulations

  • GADGET3, Zoom-in simulations, Planck Cosmology,
  • 7 haloes (DM-only) hosting present-day L* galaxies,

Mh~5x1011M☉ (Borzyszkowski+17) I. Sampling rate 20Myr => detailed assembly history

  • II. 2 haloes collapsed z ~ 0 (accreting)
  • III. 5 haloes collapsed z ~ 1.5 (stalled)

(Borzyszkowski+17)

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SLIDE 8

ZOMG! Simulations

  • GADGET3, Zoom-in simulations, Planck Cosmology,
  • 7 haloes (DM-only) hosting present-day L* galaxies,

Mh~5x1011M☉ (Borzyszkowski+17) I. Sampling rate 20Myr => detailed assembly history

  • II. 2 haloes collapsed z ~ 0 (accreting)
  • III. 5 haloes collapsed z ~ 1.5 (stalled)

Resolution independent! Introduces strong assembly bias!

(Borzyszkowski+17)

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SLIDE 9

ZOMG! Simulations

  • GADGET3, Zoom-in simulations, Planck Cosmology,
  • 7 haloes (DM-only) hosting present-day L* galaxies,

Mh~5x1011M☉ (Borzyszkowski+17) I. Sampling rate 20Myr => detailed assembly history

  • II. 2 haloes collapsed z ~ 0 (accreting)
  • III. 5 haloes collapsed z ~ 1.5 (stalled)

Resolution independent! Introduces strong assembly bias!

Embedded in filaments! Nodes!

Accreting Stalled

(Borzyszkowski+17)

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SLIDE 10

ZOMG!! Simulations

  • GADGET3, Zoom-in simulations, Planck

Cosmology. I. 4 haloes: 2 stalled + 2 accreting

  • II. DM + Hydro (UV, SNe, Winds, SF

, cooling), M* = 104M☉ ε=200pc

  • III. Mstar ~ 2-3X1010M☉, Mgas ~ 1010M☉

(Romano-Diaz+17) Moster+13
 Behroozi+13

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SLIDE 11

ZOMG!! Simulations

  • GADGET3, Zoom-in simulations, Planck

Cosmology. I. 4 haloes: 2 stalled + 2 accreting

  • II. DM + Hydro (UV, SNe, Winds, SF

, cooling), M* = 104M☉ ε=200pc

  • III. Mstar ~ 2-3X1010M☉, Mgas ~ 1010M☉

(Romano-Diaz+17)

ZOh My Gods!!

Stalled Accreting

Moster+13
 Behroozi+13

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SLIDE 12

ZOMG!! Simulations

(Romano-Diaz+17)

Stellar discs (𝜏v) Gaseous discs (Z)

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SLIDE 13

ZOMG!! Simulations

(Romano-Diaz+17)

Stellar discs (𝜏v) Gaseous discs (Z)

2 4 6 8 10 12 Time [Gyr] 1 2 3 4 5 6 6F5 [0 ⊙ yr−1 ]

6uSay 6iris Amun Abu

0.0 0.5 1.0 2.0 3.0 5.0 8.0 ]

SFR

SFR peaks close to halo formation time 
 for S-haloes

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SLIDE 14

Galaxy properties

Discs galaxies Decent agreement wrt observations, NO correlation with halo formation time! Vertical profiles S-galaxies have thicker discs! (secular evolution)

(Villalobos & Helmi 08, Bournaud+09)

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SLIDE 15

Circularity

✏∗ = jz jcirc

(Abadi+03)

  • S-galaxies have thicker discs
  • age disc coincides with SF-peak
  • Older discs for S-gals.
  • bulges are older
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SLIDE 16

Accretion

halo growth ~ 10-20%

Inflows ~ outflows

Substructures decrease 2 1.5 Analysis being done from formation halo time (S) or time of last major merger (A) Inner regions: r20 Outer regions r100

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SLIDE 17

Accretion

Infall

Matter confined (inner) regions, rapid increase 
 S - saturates z~0.6 A - increases z=0. DM Gas Infall rates A > S Only 50% goes 
 from r100 -> r20

Accretion at high-z
 ~10M☉/yr -> 2M☉/yr
 A ~ 2xS (z~0)

Recycled decreases
 at inner regions (SF)
 constant at large-r Recycled ~ Newly accreted @ z~0 @ high-z new ~ 10X recycled

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SLIDE 18

ZOMG!!!
 Satellites

Garaldi +07

Satellites at accretion:
 A-accreted on to their hosts in nearly radial orbits,
 isotropic pattern S-have a more prominent tangential component, first into filament, then onto main halo

Satellite dynamics reflect the type of halo they belong to

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SLIDE 19

Satellites

β = 1 − Σv2

t

2Σv2

r

Garaldi +17

Milky Way satellites show a prominent excess

  • f tangential orbits which is quite unusual within

the CDM paradigm (Cautun & Frenk 16)

10 Classical 
 MW satellites Different selections criteria in ZOMG

Stalled haloes show consistently -β => MW’s DM halo is stalled (?)

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SLIDE 20

Conclusions

  • Assembly bias originates by the environment of the halo
  • 1. Stalled haloes: embedded in filaments, stop growing z>1, more relaxed
  • 2. Accreting haloes: located at nodes, radial infall/orbits, not fully relaxed
  • DM is acquired via smooth & satellite accretion, no net mass accretion @r20, inflow = outflow @r300
  • Gas mimics the DM accretion patter at the halo outskirts
  • Clear distinction in central regions (r20), S-haloes consistently acquire less fresh gas than their A-counterparts. [even @ r100]
  • Due to long cooling times, gas accretion at the centre does not necessarily reflect what happens in the outskirts of the halo
  • No correlation between assembly halo time and galaxy morphology ( => implications for Halo-matching like models ? )
  • Most properties of the main galaxies are insensitive to this bias, with the exception of: ( => implications for Halo abundance-

matching like models ? )

  • A. The median stellar age of the disc component clearly reflects the halo assembly time. In S-galaxies disc started to be

assembled by z~2 (older). This process is delayed until z < 1 in the accreting haloes.

  • B. Thickness of the disc shows a clear distinction: S-galaxies are thicker by a factor of two than their A-counterparts.
  • ShMF

, radial distributions, stellar mass fractions & velocity dispersions are insensitive to the halo collapse time.

  • @z=0 the velocity anisotropy parameter of satellites is >0 for A-haloes and <0 for S-haloes. The tangential excess as

measured from classical MW satellites is ~ -2.2

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SLIDE 21

Conclusions

  • Assembly bias originates by the environment of the halo
  • 1. Stalled haloes: embedded in filaments, stop growing z>1, more relaxed
  • 2. Accreting haloes: located at nodes, radial infall/orbits, not fully relaxed
  • DM is acquired via smooth & satellite accretion, no net mass accretion @r20, inflow = outflow @r300
  • Gas mimics the DM accretion patter at the halo outskirts
  • Clear distinction in central regions (r20), S-haloes consistently acquire less fresh gas than their A-counterparts. [even @ r100]
  • Due to long cooling times, gas accretion at the centre does not necessarily reflect what happens in the outskirts of the halo
  • No correlation between assembly halo time and galaxy morphology ( => implications for Halo-matching like models ? )
  • Most properties of the main galaxies are insensitive to this bias, with the exception of: ( => implications for Halo abundance-

matching like models ? )

  • A. The median stellar age of the disc component clearly reflects the halo assembly time. In S-galaxies disc started to be

assembled by z~2 (older). This process is delayed until z < 1 in the accreting haloes.

  • B. Thickness of the disc shows a clear distinction: S-galaxies are thicker by a factor of two than their A-counterparts.
  • ShMF

, radial distributions, stellar mass fractions & velocity dispersions are insensitive to the halo collapse time.

  • @z=0 the velocity anisotropy parameter of satellites is >0 for A-haloes and <0 for S-haloes. The tangential excess as

measured from classical MW satellites is ~ -2.2

Considering all these evidence, it is thus tempting to tentatively categorise the MW halo as stalled