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First stars

First stars. When did the first star form?. ????. 1σ. Maybe as early as z~65? But certainly by z~20-30. 4σ. 5σ. 2008. atomic H, He. H 2. The basic physics is quite simple: dm/dt ~ Jean’s mass / infall time.

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First stars

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  1. First stars Bland-Hawthorn

  2. When did the first star form? ???? 1σ Maybe as early as z~65? But certainly by z~20-30 4σ 5σ Bland-Hawthorn

  3. 2008 atomic H, He H2 The basic physics is quite simple: dm/dt ~ Jean’s mass / infall time Bland-Hawthorn

  4. Bland-Hawthorn

  5. The initial core that forms in the First Stars has the same mass as the hydrostatic (stable) core that forms in stars today. The difference lies in how much gas is accreted onto the outer layers in the next few million years as gas freefalls onto the core. Star forming regions today have Tgas ~ 10K But in the early Universe, Tgas ~ 200-400 K i.e. 100x accretion rate we infer today to form stars Thus First Stars may have grown to ~103 M !!! Bland-Hawthorn

  6. Radiative feedback around the first stars. V Bromm et al.Nature459, 49-54 (2009) doi:10.1038/nature07990

  7. Bland-Hawthorn

  8. Bland-Hawthorn

  9. Bland-Hawthorn

  10. Pair instability supernova (PISN) leaves no black hole behind For a forming star with a mass 130-250 M, the core gets so hot that gamma rays collide and form matter/antimatter pairs which drain the energy. The star collapses converting a huge fraction of the mass to 56Ni. Such sources may have been seen in the local universe?! Bland-Hawthorn

  11. Where did the first black holes come from? The fact that we see powerful quasars at z~7 (see figure above) argues for some “black hole” seed at much earlier times. These must be the very rare objects that could grow at the fastest possible rate to get to mBH ~ 109 M. Bland-Hawthorn

  12. FAR FIELD To=12.90 Gyr

  13. Do these first black holes affect the chemical elements we see today? Almost certainly YES. When the first supernovae explode, we suspect that an uncertain fraction of all the metals cooked fall back towards the black hole formed at the centre. Which elements are affected in the fallback is highly controversial. Bland-Hawthorn

  14. Can we detect specific signatures of the first stellar generations today? We don’t know yet since our first star models produce chemical signatures that we can’t easily relate to the most metal poor stars (in our Galaxy) or to the most metal poor clouds at the highest redshifts. Are we looking in the wrong place? Globular cluster: These are a puzzle. [Fe/H] = -1.5 but many are >12 Gyr old! Metal poor star, [Fe/H] < -5 Faint dwarf Bland-Hawthorn

  15. Most metal-poor star CS 22892-052 There is a subtle clue here that the star is indeed extremely old. Can you spot it? [Fe/H] < -5

  16. New development: very metal poor DLAs

  17. Bland-Hawthorn

  18. Drop-out galaxies There is also the veto filter trick to look for Lya in a narrow filter, not in others, esp. for emission line sources. Famous work at Subaru.

  19. FAR FIELD To=12.88 Gyr

  20. is this believable?

  21. Star formation & QSO activity with cosmic time Hopkins & Beacom (2006)

  22. Main science driver of the James Webb Space Telescope (JWST) ~ 2018+ Bland-Hawthorn

  23. Main science driver of Square Kilometer Array (SKA) ~ 2020+ Accretion studies will be greatly advanced after the SKA comes on line. We will need the intervening decade+ to properly treat gas physics in cosmological simulations. This is a topic of the future! Bland-Hawthorn

  24. Extremely Large Telescopes 2020 ff

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