The gentle growth of high-z (>6) monsters: An application of - - PowerPoint PPT Presentation

The gentle growth of high-z (>6) monsters:

An application of Constraint Realizations

Emilio Romano-Diaz

Isaac Shlosman Jun-Hwan Choi Raphael Saudon Kentaro Nagamine Hidenobu Yajima (ApJL 2014, arXiv1411.2626Y)

1

Yehuda Hoffman

Galaxy formation

Spiral galaxies form via gas accretion (White & Rees 1978) + mergers = spherical systems (Toomre & Toomre 1972) Quiescent SF => disks Starburst are the result of mergers

2

Galaxy formation

• Observations of Gunn-Peterson trough in QSO suggest reionization ended

by z ~ 6.

• Possible sources are high-z “normal” and dwarf galaxies which are very

numerous and energetic enough to reionize the Universe (Stiavelli+04; Yan &

Windhorst 04).

• There are > 100 galaxies in 6.5 < z < 9 (Finkelstein+10; McLure+11; Bouwens+11;

Lorenzoni+11; McCracken+12)

• Galaxies even z~10!!! (?) (Bouwens+11)
• Protocluster of galaxies z~8 (Trenti+12)

3

Galaxy formation

• Discovery of QSOs z~6-8

=> SMBH M~109M⊙ (Stiavelli+05,Kim+09,Maselli+09,Utsumi+10,Mortlock+11)

=> MDM~1012M⊙

=> ρco~2.2±0.73 h3 Gpc−3 (Fan+04,Springel+05,Li+07,Overzier+09)

=> Formation clues ? (>60% mass from major mergers, Li+07)

• Great diversity of environments (Kim+09, Utsumi+10, Trenti+12)
• Recent high-z theoretical modeling indicate that major mergers are

not the main mode of growth in galaxy formation nor responsible for the intense star formation (Dayal+13; Ryan+14)

4

Galaxy formation

• Discovery of QSOs z~6-8

=> SMBH M~109M⊙ (Stiavelli+05,Kim+09,Maselli+09,Utsumi+10,Mortlock+11) => MDM~1012M⊙ => ρco~2.2±0.73 h3 Gpc−3 (Fan+04,Springel+05,Li+07,Overzier+09) => Formation clues ? (>60% mass from major mergers, Li+07)

• Great diversity of environments (Kim+09, Utsumi+10, Trenti+12)
• Recent high-z theoretical modeling indicate that major mergers are

not the main mode of growth in galaxy formation nor responsible for the intense star formation (Dayal+13; Ryan+14)

5

So, how do galaxies grow at high-z?

6

7

• Perform simulations in large volumes: (Millenium...)

I.find your most attractive guy II.Check halo characteristics (virial quantities) III.Extrapolate back in time & resimulate at higher resolution

• r

use

Constrained Realizations

(Bertschinger 86, Hoffman & Ribak 91)

How & where can we find such monsters?

Our approach

• We compare the growth of galaxies in a high-density region

against galaxies in a “normal” environment from z~6 up to z~14.

• The growth is characterized by smooth accretion and mergers.
• We use CR/UCR baryonic cosmological numerical simulations to

address this issue.

8

Simulations: IC

• CR formalism (Bertschinger 86, Hoffman & Ribak 91)
• WMAP5 Cosmology: ΩM=0.234, Ωb=0.045, ΩΛ=0.721, h0=0.701, σ8=0.817
• Halo M~1012 M⊙/h
• Collapse z~6

9

Simulations

• Gadget3: Nbody+SPH
• SF: Pressure Model ρSF=1.5X10−2M⊙pc−3 (nH,SF=1cm−3) (Schaye & dalla Vecchia 08, C&N 10)
• Cooling: H, He, metals
• Feedback: SNe, Winds (S&H 03, C&N11)
• Multi-zoom (H-R baryons: CR: r~3.5Mpc/h; UCR: r~7Mpc/h)
• M => 4X105M⊙ (DM), 105M⊙ (gas), 5X104M⊙ (stars)
• ε ~ 40 pc (physical)
• 140 output files

10

11

12

HOP group finder (Eisenstein & Hut 98): ρcrit(z) Halo: DM-only & All matter (DM+gas+*) Galaxy: a baryonic HOP-defined isodensity region with 1) ρcut = ρ0.01SFT 2) M* > 3X107M⊙ (Ryan+14) => MDM > 2X108 M⊙ Halos & galaxies traced back in time, merger history

Halos & Galaxies

13

Galaxies

14

Mergers

15

MAH: CR

16

MAH: UCR

17

Accretion

Mergers:

• A. Major: 1:3
• B. Intermediate: 4:10
• C. Minor: 10:…
• Smooth:

Matter that does not belong to any halo

Metallicity:

A. Pristine: (10-3<) B. Supsolar: [10-3,0.5] C. Solar: [0.5,1.1] D. Suprasolar: (>1.1)

Temperature:

A. Cold: (<3X104) B. Warm: [3X104,105] C. Hot: (>105)

18

Gas Accretion

19

Gas Accretion

20

Gas Accretion

1. Smooth acc. dominates 2. Minor & intermediate mergers 2nd largest cont.

Independent

• f density

environment

21

Stellar accretion

22

Stellar accretion

1. Local SF dominates growth 2. Major Mergers relevant earlier

23

Metallicity

• Galaxies “well-defined” get most of gas semi-recycled
• Supra-solar Z indication of intense SF in neighborhood
• Minimal pristine Z accretion

24

vs Observations (RT)

25 Yajima+14

Luminosity Function mm detection

Conclusions… (so far)

• CR offer a unique laboratory to address peculiar environments (high-z)
• Halos possibly precursors of QSO (z~6) harbor well defined gaseous & stellar disks.
• Our simulated disk galaxies in the over-dense regions appear consistent with the presence of

extended morphologies in bright z~7 galaxies observed by HST (Oesch+10, Ryan+14)

• Halos (independent of M) host more than 1 galaxy
• Galaxies (independently of mass) mostly grow via smooth gas accretion & in-situ SF
• Mergers deposit more stellar material than gas content (this might be dependent on feedback

mechanisms)

• Most of the gas-accreted is cold and semi-recycled.
• Small galaxies grow (as well) via smooth accretion, although they acquire more stellar content via

mergers than the one formed in-situ.

26

future…

• Cold vs hot accretion in Galaxies
• the usual suspect: feedback -> AGN, early feedback…
• Evolving U-V background…
• Different SF mechanisms…

27