Nearby Galaxy Evolution with Deep Surveys -...

Nearby Galaxy Evolution with Deep Surveys:Studying galaxies at 1<D<100 Mpc

Eric PengPeking University

Monday, December 5, 2011

Why 1 < D < 100 Mpc?

• Need to leave the Local Group for a representative sample of galaxies to study

• The Coma Cluster (100 Mpc) is the nearest truly

massive galaxy cluster• Much of what we know about the detailed properties of

galaxies is from this distance range (internal stellar populations, kinematics, star formation regions, etc).

D (Mpc)

5 kpc 10 pcTRGB+2

(I)GCLF

mean(g)milestone

0.8 22’ 2.7” 22.4 17.3 M31, nearest MW analog

4 4.3’ 0.5” 26.0 20.9NGC 5128

nearest massive E (pec)

16.5 1.0’ 0.13” 27.1 24.0 Virgo Cluster

100 10” 0.02” 31.0 27.9 Coma cluster


D (Mpc)

5 kpc 10 pcTRGB+2

(I)GCLF

mean(g)milestone


4 4.3’ 0.5” 26.0 20.9NGC 5128

nearest massive E (pec)

16.5 1.0’ 0.13” 27.1 24.0 Virgo Cluster

100 10” 0.02” 31.0 27.9 Coma cluster

Galaxies that are “too far” and “too near”

• (Only) partially resolved into stars, HII regions, substructure• Large, truly extended sources (many arcmin)

• Complicates observing strategy, standard data reduction

and analysis pipelines• Targeted observations are okay, but become “special

cases” in large surveys.


Virgo central galaxy, M87 (CFHT)


Globular Cluster Systems

dEs gEs

Globular clusters and satellite galaxies 565

Figure 1. The high-redshift and present-day mass distribution in a regionthat forms a single galaxy in a hierarchical CDM Universe. The upper panelshows the density distribution at a redshift z = 12 from a region that will forma single galaxy at z = 0 (lower panel). The blue–pink colour scale showsthe density of dark matter whilst the green regions show the particles fromprotogalaxies with virial temperature above 104 K that have collapsed at thisepoch. These peaks have masses in the range 108–1010 M!. The lower panelshows same mass distribution at z = 0. Most of the rare peaks are locatedtowards the centre of the galaxy today. The squares in both panels indicatethose first objects that survive the merging process and can be associatedwith the visible satellite galaxies today orbiting within the final galacticmass halo. Most of the subhaloes stay dark since they collapse later afterreionization has increased the Jeans mass.

is rapid and local metal enrichment occurs from stellar evolution.Metal-poor Population II stars form in large numbers in haloes aboveM H " 108 [(1 + z)/10]#3/2 M! (virial temperature 104 K), wheregas can cool efficiently and fragment via excitation of hydrogenLy!. At z > 12, these correspond to >2.5" peaks of the initialGaussian overdensity field: most of this material ends up withinthe inner few kpc of the Galaxy. Within the "1 Mpc turn-aroundregion, a few hundred such protogalaxies are assembling theirstellar systems (Kravtsov & Gnedin 2005). Typically 95 per centof these first structures merge together within a time-scale of

a few Gyr, creating the inner Galactic dark halo and its associatedold stellar population.

With an efficiency of turning baryons into stars and globular clus-ters of the order of f $ = 10 per cent, we successfully reproducethe total luminosity of the old halo population and the old dwarfspheroidal satellites. The fraction of baryons in dark matter haloesabove the atomic cooling mass at z = 12 exceeds f c = 1 per cent. Anormal stellar population with a Salpeter-type initial mass functionemits about 4000 hydrogen-ionizing photons per stellar baryon. Astar formation efficiency of 10 per cent therefore implies the emis-sion of 4 000 % f $ % f c & a few Lyman-continuum photons perbaryon in the Universe. This may be enough to photoionize anddrive to a higher adiabatic vast portion of the intergalactic medium,thereby quenching gas accretion and star formation in nearby low-mass haloes.

3 C O N N E C T I O N TO G L O BU L A R C L U S T E R SA N D H A L O S TA R S

The globular clusters that were once within the merging protogalax-ies are so dense that they survive intact and will orbit freely withinthe Galaxy. The surviving protogalaxies may be the precursors ofthe old satellite galaxies, some of which host old globular clusterssuch as Fornax, whose morphology and stellar populations are de-termined by ongoing gravitational and hydrodynamical interactionswith the Milky Way (e.g. Mayer et al. 2005).

Recent papers have attempted to address the origin of the spatialdistribution of globular clusters (e.g. Parmentier & Grebel 2005;Parmentier & Gilmore 2005). Most compelling for this model andone of the key results in this paper is that we naturally reproduce thespatial clustering of each of these old components of the galaxy. Theradial distribution of material that formed from >2.5" peaks at z >

12 now falls off as #(r ) ' r#3.5 within the Galactic halo – just as theobserved old halo stars and metal-poor globular clusters (cf. Fig. 2).

10–2

10–1

100

10–2

10–1

100

101

102

103

104

105

106

r/rvir

!(r)

/ ! cr

it.

all

1"

2"

2.5"

3"3.5"

stellar halo ~ r–3.5

globular clustersdwarf galaxies

Figure 2. The radial distribution of old stellar systems compared with rarepeaks within a z = 0 $CDM galaxy. The thick blue curve is the total massdistribution today. The labelled green curves show the present-day distribu-tion of material that collapsed into 1, 2, 2.5, 3 and 3.5" peaks at a redshift z =12. The circles show the observed spatial distribution of the Milky Way’s oldmetal-poor globular cluster system. The dashed line indicates a power law#(r ) ' r#3.5 which represents the old halo stellar population. The squaresshow the radial distribution of surviving 2.5" peaks which are slightly moreextended than the overall Navarro–Frenk–White-like mass distribution, ingood agreement with the observed spatial distribution of the Milky Way’ssatellites.

C( 2006 The Authors. Journal compilation C( 2006 RAS, MNRAS 368, 563–570

Moore et al (2006)

z=0

z=12 • GCs form early in the evolution of galaxies• Trace early, major epochs of star formation• Simple stellar populations (mostly)• Observable out to >100 Mpc, massive systems


Specific Frequency: number of GCs normalized to MV=-15

SN = NGC 10 0.4(MV+15)

Puzzle:Globular cluster formation

efficiency is not constant across galaxy mass

Peng et al. (2008)

The Properties of Globular Cluster Systems


Globular Clusters in Virgo Cluster dEs:The Role of Environment

•Dwarfs only: Mz > -19•SN vs clustercentric distance

• dEs with high GC fractions are within Dp < 1 Mpc• dEs within 100 kpc, stripped of GCs

Peng et al. (2008)


The Evolution of Massive Galaxies

Observations show little mass evolution in BCGs with

redshift

Purcell, Bullock & Zetner (2007)

• In massive clusters, N-body simulations predict that “intracluster” light dominates the light of the BCG

• Prediction: Strong correlation between ICL fraction and cluster mass

• Intracluster Globular Clusters (IGCs) should accompany ICL, and can be easier to see

DeLucia & Blaizot (2007)


HST/ACS Coma Treasury Survey (Carter et al 2008)


Globular clusters easily detected!

HST/ACS Coma Treasury Survey (Carter et al 2008)


GC spatial distribution in cluster core

Coma core GC distribution

• NGC (R<520kpc) = 70,000• “Intergalactic” GCs = 47,000• Implied ICL: 27 mag/arcsec2

• ~2500 disrupted dEs at MV=-16

~70% of GCs in N4874+IGC system are IGCs, ~30-45% of GCs in the core are IGCsConsistent with ICL measurements (Gonzalez et al) and simulations (Purcell et al)

Peng et al. (2011)

• BH-BH binaries from GCs -> Detectable source of gravitational waves? (Work in progress with Jonathan Downing)


•CFHT Large Program (2009-2012)

•104 sq. deg in ugriz• u*g’~26, r’i’z’~25

•PI: L. Ferarrese

•Galaxies, globular clusters, foreground halo, background clusters

• “Sandbox” for future surveys


The Next Generation Virgo Survey

J.-C. Cuillandre


NGVS Status (2009-2011)


IGCs in the Virgo Cluster?

ICL observations• LSB light (Mihos)• Planetary nebulae (Arnaboldi, Okamura, Feldmeier)

Mihos et al (2006)

• Best galaxy cluster for GC observations


M60

M49

M89M86

M84

Virgo globular cluster spatial

distributionCan we estimate the IGC fraction in Virgo?

Preliminary IGC fraction ranges from ~0-40% depending on chosen background region.

Need careful treatment of Galactic foreground.

MMT/Hectospec• 6.5 nights (PI: E. Peng)• ~1000 confirmed GC velocities• confirmed IGCs


Virgo and the Galactic Foreground

V. Belokurov


Virgo and the Galactic Foreground

Sgr MSTO

Virgo GCs

Virgo Overdensity


Resolving Virgo GCs in the NGVS

With 0.6” image quality:• Many bright GCs in Virgo are resolved• Star-galaxy separation becomes difficult at i>24, ~2 mag above photometric limit.


Star-GC-galaxy selection

Background galaxies

GCs

Foreground stars

Point sources

ugi selected point sources

The inclusion of u-band is extremely helpful for MW studies


Overlap regionsrh in i bandrh in g band


Sizes of Stellar Systems

• Measuring sizes of stellar systems is important for understanding them

• Globular clusters are among the smallest stellar systems

• ELTs+AO may not significantly improve survey speed for GCs in nearby galaxy clusters for certain applications

• HST and current ground-based facilities can already do a lot

0.5” seeing

HST

30m ELT

Coma

Virgo

Misgeld & Hilker (2011)


The Telescope Access Program (TAP)CFHT 3.6m

Palomar5m

MMT 6.5m

Magellan2x6.5m

Eric Peng, Shude Mao, Suijian Xue, Xiaohui Fan, Xiaowei Liu, Junxian Wang, Zhongxiang Wang, Jiasheng Huang, Lin Yan, Haojing Yan, Jiansheng Chen, Paul Ho, Fred Lo

Gang Zhao, Timothy Beers, Yu Gao, Qiusheng Gu, Raja Guhathakurta, Lei Hao, Lihwai Lin, Shengbang Qian, Hongchi Wang, Weimin Yuan


The Goals for TAP

• Promote excellent PI-led science. Do this in conjunction with other domestic

initiatives (e.g., Lijiang 2.4m).

• Build a user community for current and future projects (Dome-A, TMT, etc).

• Build our international competitiveness. We eventually need to be able to

compete on the “open market” in observational astronomy.

• To increase our ability to build instrumentation, manage projects, and

contribute “in-kind” to future international facilities.


TAP Status

• CFHT (3.6m, 15 nights/year), Palomar Hale (5m, P200, 20 nights/year)

• MMT (6.5m, 10 nights/year), Magellan (6.5m x 2, 2-4 nights/year)

• TAP will be for 3 years (2011-2014)

• 2011B: Oversubscription:1.5-3, 15 programs

• 2012A: Oversubscription: 1.5-3, 14 programs

• Next deadline, late-March, 2012 for 2012B


TAP and the Community

We held our first TAP workshop at PKU/KIAA to introduce the program to the community.• ~100 participants from all over China• International visitors from TAP observatories • Discussions on joint science programs

The 1st TAP Workshop for Optical-IR Astronomy in China PKU/KIAA, 16-17 Feb 2011

TAP Workshop, 16-17 Feb 2011

Next TAP Workshop being planned for Feb, 2012.

Call for new CFHT Large Programs (2013-2016), deadline Feb 28, 2012


The Next Generation CFHT(from Pat Côté (HIA) and the ngCFHT Concept Study Team)


• There is an exciting opportunity to capitalize on the need for extensive, wide field, highly multiplexed, optical/infrared spectroscopy in the coming decade.

• The Next Generation CFHT concept aims to create a new and expanded CFHT partnership to:

1. replace the present 3.6m primary mirror with a 10m-class (segmented) mirror, mounted on the existing pier.

2. install a dedicated wide-field (1.5 deg2) multi-object spectrograph that can simultaneously collect spectra for >3000 sources.

3. do this by ~2020 and immediately begin spectroscopic surveys. • provide the spectroscopic complement to MegaCam, PS1, Skymapper,

HyperSuprimeCam, ODI, DES, GAIA, LSST, EUCLID and WFIRST.• ngCFHT should enable focussed science for key targets and/or programs.

The Next Generation CFHT Proposal


Summary

Intergalactic GCs in Coma cluster

NGVS

GCs in Virgo

Probing Galactic halo:utility of u-band Telescope Access Program

Resolving stellar systems

D (Mpc

)

5 kpc 10 pc TRGB+2 (I)

GCLF mean(g)

milestone


4 4.3’ 0.5” 26.0 20.9 NGC 5128nearest massive E (pec)

16.5 1.0’ 0.13” 27.1 24.0 Virgo Cluster

100 10” 0.02” 31.0 27.9 Coma cluster

Nearby galaxies


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