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 EuropeanExtremely Large Telescope

Gerry Gilmore

Chair, Steering CommitteeChair, OPTICON

ELT Design Study – Contract No 011863A technology development programme funded by the European Community under its Framework Programme 6

Science case overview

Three priority themes :

Exo planets

Direct detectionIndirect detectionCircumstellar disks

Galaxy Formation

First galaxiesStellar populationsPhysics of galaxies

Frontiers of Physics

Cosmological parameters Fundamental parametersBlack Holes

• 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…)

Simulations of formation of gas giant planets via fragmentation of proto-planetary disks (Meyer et al 2004)

Radial velocity measurements of theAnd system Butler et al (1999)

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

Resolved Stellar populations

M87 in the Virgo cluster (Gendler)

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)

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)

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!

Some observed properties of Dark Matter:

a progress report on a dynamical

study of the nearby dSph’s

Gerry GilmoreIoA 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…

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?

New data: UP TO 600

*s/GAL Leo I

Note very low outer-most dispersionsin Sextans, Draco, UMi: not yet understood

Expected dispersion if no DM: <1km/s

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.

Breaking the degeneracy – first steps

Cold subsystems imply shallow density profiles: NOT as CDM prediction

Can we break the anisotropy-mass degeneracy?

Distribution Function Models

Alternative gravity theories?

Dark matter systematics: the 2005 state of play

Only 8 galaxies, factor 40 in luminosity…..

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

Systematic properties of DM –I--minimum mass, length, dispersion?

-------------

New Boo dwarf dataunder analysis

Exclusion?

Globular star clusters, no DM

Observed properties of UMa ``predicted’’

Relation now extendsfrom 40X to 500X in L,from 3 to 3000 in M/L

5 new dSph discoveredthis year, under study

Systematic properties of DM:cores, maximum central density?

Leo I

LEAST LUMINOUSLEAST LUMINOUS

MORE LUMINOUSMORE LUMINOUS

15GeV/cc

Jeans’ eqn mass profiles:total masses 3—8x10^7 MsunUnreliable method at large radiusbetter models underway

Consistent with cored halos:

UMa

Survival of cold local structures in UMi – plausibly an evolvedstar cluster -- requirescored mass distribution

Fornax

Central density ranking is the inverse rank order to CDM prediction

MOND fails

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

Systematic properties of DM -IIcores, maximum central density?

Leo I

LEAST LUMINOUSLEAST LUMINOUS

MORE LUMINOUSMORE LUMINOUS

15GeV/cc

Jeans’ eqn mass profiles:Total masses 3—8x10^7 MsunUnreliable method at large radius

Consistent with cored halos:

UMaSurvival of cold local structures in UMi – plausibly an evolvedstar cluster -- requirescored mass distribution

Kleyna etal 2003 [UMi]Kleyna etal 2004 [Sext]

Fornax

Central density ranking is the inverse rank order to CDM prediction

Distribution Functions

Exo-planets

• 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

Young Giant (5MJ) Exo-planet observed with VLT/NACO (Chauvin et al 2004)

Anisotropic Plummer Models

dark matter on small scales 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

The Local Group:detailed test

Locally, >90% halo stars are old: recent mergers?

The Local Group:detailed test

small scales: least clear,

Are the predictions reliable?

Non-Standard Models

Draco vs MOND

Mond M/L is still 19……

Are there other unmodelled effects: time-dependent dynamics?

Umi: direct HST star countsWyse etal, luminosity function for Umi is like M92, M15at low masses.High mass indirect limit from chemical evolution.

Orbit, Tidal radius Draco light is *not* tidally limited

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

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

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, AndIX with 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