1 / 49

Two-part talk

Two-part talk. Observed properties of dark matter: a progress update on dynamical studies of dwarf spheroidal galaxies The European Extremely Large Telescope (in brief..). Update on the European Extremely Large Telescope. Gerry Gilmore Chair, Steering Committee Chair, OPTICON.

jed
Download Presentation

Two-part talk

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Two-part talk • Observed properties of dark matter: a progress update on dynamical studies of dwarf spheroidal galaxies • The European Extremely Large Telescope (in brief..)

  2. Update on the EuropeanExtremely Large Telescope Gerry Gilmore Chair, Steering Committee Chair, OPTICON ELT Design Study – Contract No 011863A technology development programme funded by the European Community under its Framework Programme 6

  3. Science case overview Three priority themes : Exo planets Direct detection Indirect detection Circumstellar disks Galaxy Formation First galaxies Stellar populations Physics of galaxies Frontiers of Physics Cosmological parameters Fundamental parameters Black Holes

  4. Direct imaging detection Indirect detection (radial velocity) lower mass planets: e.g. earth-like planets around solar type stars Large collecting area (requires high spectral resolution) Stellar disks Detection of gaps where planets are forming requires high dynamic range (103-105) Spectroscopy to probe dynamics and chemistry (dust, gas & ices, organic materials…) Radial velocity measurements of the nAnd system Butler et al (1999) Simulations of formation of gas giant planets via fragmentation of proto-planetary disks(Meyer et al 2004)

  5. Resolved Stellar populations Aparicio and Gallert (2004) • Measuring age & chemical composition of individual stars •  quantify star formation and assembly histories of a galaxy • Map dark matter • (i) Colour-magnitude diagram (photometry) • A ~40m can reach RGB stars for representative galaxies in Virgo/Fornax at ~17Mpc • (ii) Spectroscopic chemical abundances & kinematics • High resolution (diffraction-limited) • Large collecting area M87 in the Virgo cluster (Gendler)

  6. Galaxy Formation- The first galaxies • Redshift ~ 6-7 galaxies have been found • Evidence for higher redshift galaxies: • Old stellar populations, SMBH already seen at z~6 • Universe is ionised by something! • Find earlier galaxies by imaging: JWST? ELT imager? • Need ELT for continuum spectroscopy(z and physical properties) • Large collecting area (faint galaxies) • Large Field of View HST images of z~5 galaxies (Bremer & Lehnert 2005)

  7. Frontiers of Physics • Dark Matter • Probe via galaxy dynamics • Dark Energy • Type Ia SNe spectroscopy at hi-z • Direct measurement of expansion • [e.g. CODEX, R~150,000] • Variation of fundamental parameters • Black Holes • angular resolution of ELT probes “sphere of influence” Artist’s concept of an AGN (GLAST/NASA) Keck observations of Q1422+231 (Sargent & Rauch)

  8. E-ELT Current status • Technical review of general design work late 2005 • Specific designs under study for next review late 2006 • Apertures in range 30m-60m considered, 30-40m likely: driven by schedule  to match JWST and ALMA; cost and technology • Major science/technology meeting, 11/2006 (Marseille) • Then progress to detailed design • Cost ~1G$/euro • Schedule: operation ~2016: the second set of Great Observatories • ESO Council resolution: We will do it, and not be late • Two similar projects, status and timetables in US • Presentation of major 2015+ projects, and funding agency overviews, next week @ Prague, IAU GA (Special Session 1) Real why: more photons and resolution = more science!

  9. Some observed properties of Dark Matter:a progress report on a dynamical study ofthe nearby dSph’s Gerry Gilmore IoA Cambridge Mark Wilkinson, Jan Kleyna, Wyn Evans, Justin Read, Andreas Koch, Rosie Wyse, Mike Irwin, Eva Grebel,,…. Data from: VLT, Keck, Gemini, AAT, WHT, INT, eso2.2…

  10. The early context • The ``standard’’ value for local DM at the Sun is 0.3GeV/cc, all in a `halo’ component • (cf pdg.lbl.gov: Eidelman etal 2004) • the original work, and origin of this value, is the first analysis to include a full 3-D gravitational potential, parametric modelling, and a direct determination of both the relevant density scale length and kinematic (pressure) gradients from data, allowing full DF modelling for the first time: Kuijken & Gilmore 1989 (MN 239 571, 605, 651), 1991 (ApJ 367 L9); 1989 Gilmore, Wyse & Kuijken (ARAA 27 555) • Cf Bienayme etal 2006 A&A 446 933 for a recent study • Dark halos are `predicted’ down to sub-earth masses; but… • Neither the local disk, nor star clusters, have DM: Given the absence of a ~100pc local enhancement, what is the smallest scale on which DM is concentrated?

  11. Leo I New data: UP TO 600 *s/GAL Note very low outer-most dispersions in Sextans, Draco, UMi: not yet understood Expected dispersion if no DM: <1km/s

  12. dSph modelling • 1) Use Jeans’ eqn: simple, and robust: also • 2) Multi-component DF models developed (see Wilkinson etal MN 330 778 2002 for details) • Construct parameterised equilibrium dynamical models – vary halo shape, and mass, stellar velocity anisotropy • Predict line of sight kinematics: convolve with observational effects (errors, binaries, sampling…) • Compare with individual data to find best-fit model • OTHER COMPLEMENTARY WORK: • Deep HST studies to show stellar M/L `normal’, [ie agrees with Kroupa, Tout, Gilmore local IMF: -- Wyse etal 2002 New Astr 7 395 for UMi] • Galactic tides, feedback, etc modelled (eg Read etal 2006 MN 366 429) • NOTE many earlier studies used scaled tidally-limited star-cluster (King-) models: these are invalid for extended low-density systems.

  13. Breaking the degeneracy – first steps

  14. Cold subsystems imply shallow density profiles: NOT as CDM prediction

  15. Can we break the anisotropy-mass degeneracy?

  16. Distribution Function Models

  17. Alternative gravity theories?

  18. Dark matter systematics: the 2005 state of play Only 8 galaxies, factor 40 in luminosity…..

  19. Systematic properties of DM –I--minimum mass, scale, dispersion?2006: extend dynamic range by 2 mags • Red line: constant mass DM halo, • M~4x107M • apparent lower mass boundary • Some data are old, central M/L only • Now a factor of 200+ in luminosity, 3000+ in M/L Figure from astroph-0602186

  20. Systematic properties of DM –I--minimum mass, length, dispersion? Observed properties of UMa ``predicted’’ New Boo dwarf data under analysis  Relation now extends from 40X to 500X in L, from 3 to 3000 in M/L 5 new dSph discovered this year, under study ------------- Exclusion? Globular star clusters, no DM

  21. Systematic properties of DM:cores, maximum central density? Survival of cold local structures in UMi – plausibly an evolved star cluster -- requires cored mass distribution Consistent with cored halos: 15GeV/cc LEAST LUMINOUS  UMa Jeans’ eqn mass profiles: total masses 3—8x10^7 Msun Unreliable method at large radius better models underway Fornax  Leo I MORE LUMINOUS Central density ranking is the inverse rank order to CDM prediction MOND fails

  22. New dSph – and debris – being discovered now: test predictions!

  23. Systematic properties of DM -IIcores, maximum central density? Jeans’ eqn mass profiles: Total masses 3—8x10^7 Msun Unreliable method at large radius Consistent with cored halos: 15GeV/cc LEAST LUMINOUS  UMa Survival of cold local structures in UMi – plausibly an evolved star cluster -- requires cored mass distribution Kleyna etal 2003 [UMi] Kleyna etal 2004 [Sext] Fornax  Leo I MORE LUMINOUS Central density ranking is the inverse rank order to CDM prediction

  24. Distribution Functions

  25. How common are systems like ours? How do planetary systems form? To date many planets have been detected indirectly Direct detection: Mass, radius, temperature, composition ELT will provide large samples of mature giant planets in reflected light Earth-like planets may be within reach Large collecting area (faint planets) Large diameter: very high spatial resolution and contrast ~109 Exo-planets Young Giant (5MJ) Exo-planet observed with VLT/NACO (Chauvin et al 2004)

  26. Anisotropic Plummer Models

  27. A vast increase in precise stellar kinematic data allows more sophisticated derivation of mass profiles in the dSph- the smallest galaxies. UMa – discovered 2005 and Boo (2006) – extends to M/L ~ 500-3000!! 4 more found last week… All are consistent with: Central mass cores, not cusps Central mass density ≤20GeV/cc Dispersion ~6-9km/s Scale length ~few x100pc DM minimum mass? ~5x107M We have new dSph under study (today), to extend the sample further, and see if these numbers are really significant MOND fails dark matter on small scales

  28. The Local Group:detailed test Locally, >90% halo stars are old: recent mergers?

  29. The Local Group:detailed test small scales: least clear, Are the predictions reliable?

  30. Non-Standard Models • Draco vs MOND • Mond M/L is still 19……

  31. Are there other unmodelled effects: time-dependent dynamics?

  32. Umi: direct HST star counts Wyse etal, luminosity function for Umi is like M92, M15 at low masses. High mass indirect limit from chemical evolution.

  33. Orbit, Tidal radius • Draco light is *not* tidally limited

  34. High-mass, high-redshift IMF • Element ratio modelling limits IMF slope

  35. dSph Stellar IMF Deep direct star counts (Wyse etal) Element ratio limits at high mass Deep ISO photometry (GG + Unavane) All imply an invariant IMF  Stellar M/L=2-4

  36. dSph satellite galaxies: what, why? • Lowest stellar mass galaxies known • In CDM test regime: eg famous sub-structure problem • (ie, >1000 predicted, ~10 found) • Have high M/L (Aaronson 1983) – 3 stars in Draco to deduce M/L=30 1-D velocity dispersion high • 1990 Pryor & Kormendy showed that extended dark halos were consistent with available data • 1997 Mateo: first extended dispersion profile –Fornax • 1998 Mateo noted M/L vs L may imply min DM mass. • 2006: extended dispersion profiles available for Draco,UMi,Leo I, Leo II, Fornax, Scl, Carina, …1-D for UMa, AndII, AndIXwith very many high-precision data – up to >500 stars/galaxy [new ones to come – complete sample] • Kleyna etal 2000,2002,2003,2004, 2005, 2006;Tolstoy etal 2004, 2006; Munoz etal 2005; Walker etal 2005;Chapman etal 2005; Wilkinson etal 2004, 2006, Koch etal 06a, 06b

More Related