The Formation of Population III Protostars. Matthew Turk - Stanford/KIPAC with Tom Abel (Stanford/KIPAC)

Transcription

1 The Formation of Population III Protostars Matthew Turk - Stanford/KIPAC with Tom Abel (Stanford/KIPAC)

2 (preamble)

3 Population III Stars

4 Population III

5 Population III

6 Population III.1

7 Population III.2

8 Population III.1 Population III.2

9 Population III.1 Population III.2

10 The Story So Far

11 (some of) The Story So Far

12 Many published studies! Bromm, Coppi & Larson Omukai & Palla Heger & Woosley

13 Abel, Anninos, Norman & Zhang (1998) First nested grid calculation

14 Abel, Bryan & Norman (2002) First AMR calculation Single star forming in isolation solar masses

15 O Shea & Norman (2007) Many realizations Collapse time affects accretion rates Accretion rates: uncertain!

16 Yoshida et al (2006, 2008) SPH with particle splitting Advanced chemistry Formed a protostar

17 Baryons Dark Matter

18

19

20 z ~ 30 { 10 6 M

21 Controlled by H2 cooling

22 Form Alone

23 Massive

24 Questions:

25 1. In what way do H2 formation rates affect collapse?

26 2. Can we constrain the initial mass function?

27 3. What can this tell us about enrichment?

28 3. What can this tell us about enrichment? ( )

29 How can we study these objects?

30 AMR

31 Universe

32

33 BORING BORING INTERESTING BORING

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43 Chemistry

44 Very Simple Chemistry Helium 24% Hydrogen 76%

45 Very Simple Chemistry Helium 24% H H + He He + He ++ e - H - H2 H2+ Hydrogen 76% D D + HD

46 Very Simple Chemistry Helium 24% Hydrogen 76% H H + He He + He ++ e - H - H2 H2 + D D + HD

47 Very Simple Chemistry Helium 24% Hydrogen 76% H H + He He + He ++ e - H - H2 H2 + D D + HD

48 Process Time CMB Star See work by Glover, Omukai, Galli, Palla, Shull, Abel,...

49 Process Density CMB Star See work by Glover, Omukai, Galli, Palla, Shull, Abel,...

50 10-2 Background! H2 forms via H - channel

51 10-2 Background! H2 forms via H - channel Molecular Hydrogen Fraction: 2x10-6

52 10 4 Roto-Vibrational Levels Molecular Hydrogen Fraction: 10-3

53 10 4 (Full) Roto-Vibrational Levels Molecular Hydrogen Fraction: 10-3

54 10 4 Density independent cooling Molecular Hydrogen Fraction: 10-3

55 10 7 Three-body! H 2 + H 3H 2H + H 2 2H 2 2H + H H 2 + H H 2 + H 2 2H + H 2 Molecular Hydrogen Fraction: ~1.0 Glover 2008, Turk et al (in prep)

56 10 12 Optically Thick Molecular Hydrogen Fraction: ~1.0 See Ripamonti & Abel 2004

57 10 14 Collision Induced Emission H2 H2 Molecular Hydrogen Fraction: ~1.0

58 10 14 Collision Induced Emission H2 H2 H2 H2 Molecular Hydrogen Fraction: ~1.0

59 10 14 Collision Induced Emission H2 H2 H2 H2 Molecular Hydrogen Fraction: ~1.0

60 10 20 Molecular Hydrogen Fraction: << 1

61 10 20 T ~ 20,000K Molecular Hydrogen Fraction: << 1

62 10 20 T ~ 20,000K Code breakdown! Molecular Hydrogen Fraction: << 1

63 Adaptive Mesh Refinement (patch-based) N-body Dark Matter Radiative Cooling 12-species chemistry model

64 Adaptive Mesh Refinement (patch-based) N-body Dark Matter Radiative Cooling 12-species chemistry model Spatial Range of 2 42

65 Adaptive Mesh Refinement (patch-based) N-body Dark Matter Radiative Cooling 12-species chemistry model Spatial Range of 2 42 Protostellar densities

66 (Earth) (Flu Virus)

67 300 kpc h-1

68 300 kpc h-1

69 3.2 x 10 9 Solar Masses 300 kpc h -1

70 3.2 x 10 9 Solar Masses 300 kpc h -1

71 3.2 x 10 9 Solar Masses 300 kpc h -1

72 Limitations

73 Box Size Wave modes truncated at L -1

74 Courant Condition

75 H2 Formation Rates (with Paul Clark, Simon Glover, Ralf Klessen, Thomas Greif)

76 Dissociation ~1800K Association

77 Problem Setup Cosmological Initial Conditions Branched at 10 2 cm cells per Jeans Length Stopped at cm -3 Internal comparison

78 5000 AU (10-14 g/cc) (Glover 2008)

79 500 AU (10-12 g/cc) (Glover 2008)

80 50 AU (10-10 g/cc) (Glover 2008)

81 Higher H2 Rates Lower H2 Rates

82 Forming a Protostar

83 Problem Setup Three sets of initial conditions 16 cells per Jeans Length Stopped at ~10 19 cm -3

84 Problem Setup Three sets of initial conditions 16 cells per Jeans Length Stopped at ~10 19 cm levels of refinement 0.3 solar radii

85 500 AU 50 AU 5 AU 0.5 AU g/cc g/cc 10-8 g/cc 10-8 g/cc

86 100 AU

87 100 AU

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90 Density x y g/cc z 250 AU SIM2 Temperature H2 Fraction 2000K 10% H2

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92 Hotter gas

93 Faster accretion

94 ...more massive?

95 Metal Pollution

96 Smith et al 2008

97 Wise & Abel

98 What s next?

99 Sink Particles. Self-consistent means of avoiding the courant condition.

100 Bigger Boxes. 300 kpc h Mpc h -1

101 More realizations. Separate formation environment from formation physics.

102 Accretion Simulations. Full radiative transfer with an evolving accretion shock, followed for many mass-doublings.

103 Thank you. Additional thanks to: Greg Bryan (Columbia) Mike Norman (UCSD) Simon Glover (Heidelberg) Britton Smith (UC Boulder) John Wise (NASA/Goddard) Jeff Oishi (UC Berkeley)