Extragalactic Globular Cluster Systems - Portal IAG · Extragalactic Globular Cluster Systems Theoretical Paradigms Prospects for E-ELT Outline of Talk ... Moeda: Libra esterlina

Extragalactic Globular Cluster

SystemsRay Sharples

Centre for Advanced Instrumentation

Centre for Extragalactic Astronomy

Stellar Populations Newton Meeting

Durham University, UK

Extragalactic Globular Clusters as

Probes of Galaxy Formation Theories

Photometric & Spectroscopic Studies of

Extragalactic Globular Cluster Systems

Theoretical Paradigms

Prospects for E-ELT

Outline of Talk


Centre for Extragalactic

Astronomy


55 Members:

16 Academic staff13 Postdocs/research fellows4 Operations 22 PhD students

Environment and Galaxy Evolution Physics of High-Redshift Galaxies Gas and Galaxies AGN Feedback Gravitational Lensing Survey Cosmology

Institute for Computational

Cosmology

12 Academic staff, 15 Postdocs, 23 PhD students

COSMA4: 3000 Intel X5650 cores,

15TByte DDR3 RAM

Dados do mapa ©2015 GeoBasis-DE/BKG (©2009),Google,Inst. Geogr. Nacional 200 km

United Kingdom

Fatos rápidos

Reino Unido, oHcialmente Reino Unido da Grã-Bretanha e Irlanda do Norte, é um Estado soberano insular

localizado em frente à costa noroeste do continente europeu. Wikipédia

Moeda: Libra esterlina

Capital: Londres

Fotos Street View

United Kingdom

Durham

Centre for Advanced

Instrumentation


70 Members:

12 Academic staff16 Instrument scientists16 Engineers (optical,mech,elec,soft) 4 Operations 22 PhD students

Astronomical Instrumentation Applied Optics & BioPhotonics Precision Optics Manufacture/Metrology Remote Sensing Fusion Diagnostics (EPSRC CDT) Gamma ray instrumentation (CTA)

NetPark Research Institute

Space Based

Ground Based

Adaptive Optics

Why Extragalactic Globular

Clusters ?

• Found ubiquitously around all galaxies

understanding of both spheroidal and disk galaxies

• Oldest stellar populations with reliable ages

probe earliest phases of galaxy assembly

• Scale approximately with host galaxy mass

intimate connection with galaxy formation

• Easier to model than integrated light (SSP)

disentangle composite stellar populations


Bimodality in Colour Distributions

M87

Blue Red

Metal-poor Metal-rich

Generally interpreted

as a metallicity effect


V-I = 0.95 1.15 [Fe/H] = -1.5 -0.5

Bimodal color distributions

globular cluster sub-populations

Color differences are

due to

age differences

and /or

metallicity differences

Multiple epochs

and/or mechanisms

of formation





Strader

2007

Galaxies

Bimodality in Metallicity Distributions


Brodie &

Strader

2007

EGC/Galaxy

Formation Models

1. Formation of GCs in mergers (Schweizer 1987,

Ashman & Zepf 1992)

2. In situ/multi-phase collapse (Forbes, Brodie & Grillmair 1997)

3. Accretion/stripping(Cote et al. 1998)

4. Hierarchical merging(Beasley et al. 2002)

Require truncation of GC formation at high redshift

z

Possible Scenarios for EGC

Formation

1. Blue clusters form in progenitor galaxy

fragments, red clusters in mergers

2. Blue and red clusters represent different

phases of initial galactic collapse

3. Red clusters form during initial collapse, blue

clusters accreted later

key diagnostics are relative ages and kinematics

need to consider formation and destruction processes


Age-Metallicity Distributions

Puzia et al (2004)Stellar Populations Newton Meeting

Lick

Indices

Burstein et al. 1984

Worthey et al. 1994

Age-Metallicity DistributionsPuzia et al (2004)

Thomas et al (2003, 2004)

NGC1380 S0

NGC2434 E0

NGC3115 S0

NGC3379 E1

[Fe/H]<-0.8

clusters span

narrow age range

around 12Gyr.

[Fe/H]>-0.8

clusters show

range in ages over

several Gyr.Stellar Populations Newton Meeting

-element EnrichmentPuzia et al (2005)

[/Fe] > 0 indicates

a short star

formation timescale

(or flattened IMF).

Metal-rich [Fe/H]>-

0.8 clusters span

wide range in [/Fe]

.

Intermediate-age

GC have lower

[/Fe] than old

clusters. Stellar Populations Newton Meeting

EGC System KinematicsNGC4472

Sharples et al (1998)


blue

red

NGC4649

Pota et al (2015)

Re

Cole et al (2000)Stellar Populations Newton Meeting

SAM Colour Distributions


Beasley et al (2002)

See also Kruijssen

(2015)

Bekki et al (2008)

Extragalactic GCs with ELTs

•Deep spectroscopic surveys of representative

samples of GCs

•Explore range of morphological types (E-Sc)

•Range of environments (rich clusters – groups

– field)

•M*+4 < M < M*-2

•Spectral resolution to enable direct model-

fitting

•Determination of age, [Fe/H], [α/Fe], velocity


ELT-MOS Requirements

•Spectroscopy over 3` (7` for NGC1399) diameter fields

out to Fornax cluster (19 Mpc)

•Half light radii 2-3pc 0``.15 arcsec aperture (0``.4

convolved with GLAO PSF)

•GCLF peak at D=19 Mpc: V~24.5, J~22.4

•S/N > 50 per A at R~5000 texp ~ 10 hrs

•Multiplex N ~ 100 for ellipticals (N ~ 50 for spirals)

•Ntargets ~ 100 gal MB > -16 D < 20 Mpc

•Wavelength range: 0.38-0.68 μm [0.8-1.4 μm]


ELT-HIRES Requirements

• Multiplex (N~10) feed to ELT-HIRES

• R~20,000 brightest targets only.


Milky Way GCs

Bernstein & McWilliam (2002)

Colucci et al (2009,2011, 2012)

R>20,000

S/N > 60 per A

Mg, Al, Si, Ca,

Sc, Ti, V Cr,

Mn, Fe, Co, Ni,

Y, and Ba.

Young Massive Star Clusters in

Merging Galaxies


• Observation of young massive star clusters in many

merger remnants gave a significant boost to the major

disk-disk merger model for GC bimodality

• Masses and sizes should allow them to evolve into old

GCs but may have abnormal IMFs that preclude their

long-term survival

• Merger conditions at high-z may be very different to

mergers in present day universe

KMOS Spectroscopy of

Antennae YMCs


KMOS mounted on Antu

The Antennae (NGC 4038/4039)The Antennae (NGC 4038/4039)

All clusters observed spectroscopically so far

All clusters observed spectroscopically so far

RGB image from CTIO - ChileRGB image from CTIO - Chile

Typical SpectraTypical Spectra

Gilbert B1Gilbert B1

Gilbert BGilbert B Christopher 68Christopher 68

Christopher 65Christopher 65

Typical spectral cubes

Spiral-spiral merger D~19 Mpc

First close passage 300 Myrs ago

Intermediate merger stage

KMOS Spectroscopy of

Antennae YMCs


Chapter 4. The Antennae: NGC 4038/ 4039 113

Figur e 4.18: Top-Left: Dots represent [Paβ/ Paγ] line rat ios obtained from

our star cluster sample in the YJ band. The red line represents the best fit

to the observed rat ios. Bottom-Left: Same as top-left but now for [FeI I/ Paβ]

line rat ios. Top-Right: Same layout as top-left but now for [H2/ Brγ] line rat ios

measured from star clusters in theK band. Bottom-Right: Sameas top-r ight but

now for [FeI I/ Brγ] line rat ios, where FeI I emission was measured in the H band.

Line rat ios from nuclear and HI I regions in star forming galaxies, measured by

Dale et al. (2004), are plot ted in black for comparison. Errors for these line

rat ios are plot ted where available.

age suggests that thermal shock excitat ion from SNRs is becoming increasingly

important in ionising gas within a star cluster as it evolves.

In addit ion to theselinerat ios, Figure4.18 showshow [Paβ/ Paγ] linerat io variesas

a funct ion of age. Large[Paβ/ Paγ] linerat iosrequirehigh excitat ion temperatures,

hence the observed linear decrease of this line rat io with age possibly represents

a decrease in temperature within a star cluster as it evolves (Kwan and Fischer,

2011). Massive OB stars are responsible for ionising gas that produce strong

hydrogen recombinat ion lines. Therefore, this decrease in temperature is likely

due to the decline of massive OB stars in star clusters as they evolve.


Conclusions

• Extragalactic GCs are among the oldest radiant objects in the universe

• Typical masses ∼104–106 M⊙ (MV = −5 to −10) and compact sizes

make them readily observable in external galaxies out to D~20 Mpc

• Can constrain the star formation and assembly histories of galaxies,

nucleosynthetic processes governing chemical evolution, epoch and

homogeneity of cosmic reionization, role of dark matter in the

formation of structure in the early universe, and distribution of dark

matter in present-day galaxies

• Multiplexed observations with E-ELT are set to have a major impact

on the field

• Also need for improved numerical and semianalytic simulations to help

identify GC formation sites and track their spatial, kinematic, chemical,

and structural evolution

Documents

Extragalactic Globular Cluster Systems - Portal IAG · Extragalactic Globular Cluster Systems Theoretical Paradigms Prospects for E-ELT Outline of Talk ... Moeda: Libra esterlina