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Accretion through cosmic time: formation of the first galaxies galaxy evolution to the present day

Accretion through cosmic time: formation of the first galaxies galaxy evolution to the present day. Joss Bland-Hawthorn (University of Sydney). Drop-out galaxies. FAR FIELD. T o =12.88 Gyr. is this believable?. Star formation & QSO activity with cosmic time. Hopkins & Beacom (2006).

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Accretion through cosmic time: formation of the first galaxies galaxy evolution to the present day

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  1. Accretion through cosmic time:formation of the first galaxiesgalaxy evolution to the present day Joss Bland-Hawthorn (University of Sydney)

  2. Drop-out galaxies

  3. FAR FIELD To=12.88 Gyr

  4. is this believable?

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

  6. Overview Earliest fossil of accretion ✔ Dark age accretion ✔ Spherical top-hat model Virialization Gunn & Gott accretion model “Nature operates by rules we can discover in successive approximations…” Bland-Hawthorn

  7. First galaxies Bland-Hawthorn

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

  9. I will now introduce some theoretical concepts that have been useful in understanding how non-linear structure forms out of linear perturbations. We will meet important ideas that are used in comparing simulations with data. Bland-Hawthorn

  10. Some basic theory: . a a  Bland-Hawthorn

  11. open marginally bound closed In the marginally bound, matter dominated (Einstein-de Sitter) universe: a(t)  t2/3 We will adopt EdS universe as it simplifies algebra and everyone uses it. Bland-Hawthorn

  12. Spherical Collapse R1 R2 1 2 Solutions to (2) G Bland-Hawthorn

  13. Bland-Hawthorn

  14. Nowadays, R200 is more conventional within CDM Amazing fact: The DM halo of M31 is tens of degrees in size as "seen" from Earth. See what follows. Bland-Hawthorn

  15. The Metal-Poor Halo of the Andromeda Spiral Galaxy K.Gilbert M31 Image from GALEX Bland-Hawthorn Feb. 7th, 2006 Local Group Cosmology, Aspen CO

  16. The Metal-Poor Halo of the Andromeda Spiral Galaxy R200 for M31 M31 Image from GALEX Bland-Hawthorn Feb. 7th, 2006 Local Group Cosmology, Aspen CO

  17. NFW halo dominates research today Bland-Hawthorn

  18. Bland-Hawthorn

  19. Why is there a core-halo structure in galaxies? (simple 1D kinematic argument) N sheets start together at x=0, expand with Hubble flow, then collapse under mutual self gravity. Simple equation of motion depends only on number of sheets either side of sheeti The force from one sheet is a constant everywhere, i.e. no distance dependence. We track sheets that have crossed. For infinite 2D sheets, the force law depends only on number above minus number below: The inner sheets have to climb out of a deeper well than when they fell in; the delayed outer sheets infall and climb out of a shallower well. This transfers energy to the outer sheets.  core-halo structure later start halo core Bland-Hawthorn

  20. Bland-Hawthorn

  21. Bland-Hawthorn

  22. Mo is a constant RαM1/3 sinceρwithin infalling shells is a constant This is one of a much wider class of similarity solutions for collapse (e.g. Bertschinger 1984; Fillmore & Goldreich 1984) Bland-Hawthorn

  23. Overview Infall on cosmic scales (linear) Infall onto groups and clusters (non-linear) Infall onto galaxies Disk formation: Fall's argument Angular momentum build-up (in brief) Hot halos  cooling flows Cold flows, warm flows Recycling and feedback Galaxy formation within ΛCDM: score card “Nature operates by rules we can discover in successive approximations…” Bland-Hawthorn

  24. Do we observe cosmic infall over huge homogeneous volumes ? Bland-Hawthorn

  25. Cosmic infall out to z~0.2 transverse Zero quadrupole 2001 radial fingers of god Kaiser flattening Bland-Hawthorn

  26. Cosmic infall at z~3.6 Two sets of QSO pairs added pancake model Ly absorbers along paired QSO sightlines Bland-Hawthorn

  27. Kinematic infall around groups & clusters… Can we see coherent infall into observed clusters? Take the Great Attractor for example, a part of the sky where we see bulk motions of galaxies. This topic, like so many in astronomy, has a chequered history. Easy to detect this, right? 1990: they claimed to see nearside and farside infall 1988 Famous paper: Seven Samurai detect GA?! Control sample Bland-Hawthorn

  28. Disputed, at least on the far side... A little known and very good paper on how to do the statistics right, Malmquist bias, noise, pairwise velocity... this is hard to do properly! Bland-Hawthorn

  29. So how does gas get into galaxies? It's hard to understand how gas gets into galaxies for two reasons: (1) much of the activity happened long ago; (2) we cannot easily see or locate cold, warm, hot gas in the local universe, especially if it is diffuse. • So many things we don’t know: • Does the gas arrive hot, warm, cold? • Does it fall in with dark matter? • Once arrived, does it change state before settling to the disk? • Does the gas stay in the galaxy, or does feedback (AGN, starburst, radiation) push it back out? • Does it depend on the type of galaxy or the environment the galaxy is in? Bland-Hawthorn

  30. Hot accretion via cooling in haloes — central tenet of GF • History: Hoyle 1953, Binney 1977, Rees & Ostriker 1977, Silk 1977, White & Rees 1978, White & Frenk 1991… Bland-Hawthorn

  31. Hot gas cooling within the dark halo:  . r So for our Galaxy with Vc ~ 200 km s-1, TVIR ~ 2x106 K  soft x-ray gas. In rich clusters, Vc ~ 1000 km s-1, TVIR ~ 5x107 K  hard x-ray gas. r The famous “cooling flow” argument. But is this what we really see??? Bland-Hawthorn

  32. 1994 . Bland-Hawthorn

  33. Do cooling flows exist? • Not according to XMM/Newton spectra of 14 top-ranked “cooling flow” clusters. Peterson et al 2003 Something appears to keep the gas hot… …black holes appear to provide an important source of feedback Expected — huge cooling flow predicted Observed — too hot for substantial cooling Bland-Hawthorn

  34. Disks through cooling flows? 2004 2006 They ignore the long literature on thermal instability in cooling flows. Linear thermal instability is almost completely suppressed (because an overdense blob convects back to its equilibrium location faster than an instability can grow); Binney, Nipoti, Fraternali 09. Non-linear thermal instability possible but tends to produce tiny fragmentary clouds. SPH is not the way to do this. Bland-Hawthorn

  35. Pedersen+ 06; Rasmussen+ 06 Don't believe papers that make these claims. Extraordinary claims require extraordinary evidence. Almost any disk with a hot halo is a galactic wind or the data have not been reduced properly. Bland-Hawthorn

  36. NEXT TIME: This appears to be first reliable detection after the Galaxy …and the amount of cooling is far too small to create the disk. Bland-Hawthorn

  37. Disk formation Disk formation

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