Cosmology from Large-Scale Galaxy Surveys Matthew Colless, - - PowerPoint PPT Presentation

Cosmology from Large-Scale Galaxy Surveys

Matthew Colless, Anglo-Australian Observatory A Century of Cosmology, Venice, 27-31 August 2007

A brief history of galaxy surveys

Before 1980: Pre-history - first galaxy redshift surveys

Hubble, the expanding universe, and all that

1985-1995: Age of Discovery - large-scale structures

The CfA redshift survey and the iconic stick-figure The development of multi-object spectrographs Large (104) z-surveys - LDSS, Autofib, PSCz, LCRS…

1995-2005: Industrial Revolution - ‘precision cosmology’

Massive (105) z-surveys - 2dFGRS, SDSS, 6dFGS, 2MRS… Deep z-surveys - DEEP, VVDS, zCOSMOS…

Present & future: Post-Modernism - death or glory?

Dark energy - holy grail? much ado about nothing? BAO (106) surveys - WiggleZ, FASTsound, WFMOS… Galaxy surveys with ELTs - baryon tomography…

AAO

FOC FOCAP LDSS LDSS Autofib utofib 2d 2dF 6d 6dF AA WFM FMOS OS

Las Campanas Redshift Survey ~25000 z’s

State of the art ~1997

CfA fA Survey ~15000 z z’s

Evolution of Redshift Surveys

2dFGRS SDSS

UK Schmidt Telescope (1.2m) Anglo-Australian Telescope (3.9m)

Surveys with the AAT & UKST

The 2-degree Field Spectrograph

Multi-ob ulti-object ject fi fibre re sp spectrog ectrogra raph w h with ith rob robotic

• tic positioner
• sitioner

Sp Spectra ectra for 400 for 400 gala laxies ov xies over 2º er 2º 2d 2dF ena F enabled led a a massiv ssive e z-surv urvey ey

The 2dFGRS map of 221000 galaxies

The large-scale structure of the galaxy distribution, on scales from millions to billions of light-years, depends on… the amounts of the various constituents of the universe (baryonic matter, dark matter, dark energy etc.) the recipe for how galaxies are formed (when, where, and with what bias relative to the dark matter) The rich structure of the galaxy distribution encodes much physics and many parameters

100 million light-years

Large-Scale Structure in Model Universes

Surveys versus simulations

Comparis ison of slic lices fr from CfA fA2, 2dFGRS and SDSS surveys on diffe ifferent scale les, all ll compared to equiv ivale lent slic lices, sele lected fo for their ir sim imila ilarit ity, fr from the Mille illenniu ium Sim imula latio ion (Sprin

pringe gel, Fre renk k & W White ite 2 2006)

2dFGRS structure & cosmology results

The large-scale structure of the galaxy distribution is reliable and precisely determined on size scales from 1 Mpc to 200 Mpc The properties of the galaxy distribution confirm that the large-scale structure grows by gravitational instability… consistent with quantum fluctuations emerging from Big Bang being amplified by gravity into galaxies/clusters/superclusters The total density of all types of matter in the universe is M = 0.23 there is only 23% of critical density needed for a flat universe The total density in ordinary matter is B = 0.04 baryons are 19% and CDM is 81% of all matter in the universe Neutrinos make up less than 13% of all the matter in the universe the total mass of the 3 neutrino species is less than 0.7 eV First detection of baryon acoustic oscillations (simultaneous with SDSS)

2dFGRS structure & cosmology results

Composition of the cosmos

19% 19% 77% 77%

SNe CMB Baryons

The 6dF Galaxy Survey

A redshift & peculiar velocity survey

• f galaxies in the local universe

Covers southern sky with |b|>10º Primary galaxy sample selected from 2MASS with Ktot<12.75 Also H<13.0, J<13.75 (2MASS) and r<15.6, b<16.75 (SuperCosmos) 11 other samples: radio, X-ray, IRAS Peculiar velocity survey uses FP for 15,000 bright early-type galaxies Observations obtained May 2001 to Jan 2006 using 6dF spectrograph on the UK Schmidt Telescope Database:137k spectra, 124k galaxy redshifts over 80% of southern sky Final data release Aug 2007

Sky coverage & redshift completeness

Obse bserve rved 1 d 1464/1 /1598 fi fields; 9 lds; 92% o

• f th

the so south thern rn sky sky w with ith |b|> |b|>10° Mean an re redsh dshif ift c t comple plete teness ss for th r the K-ban K-band prim d primary ary sam sample ple is 8 is 88%

Comparison with other z-surveys

Comparing the 6dFGS to the 2dFGRS and SDSS…

6dFGS galaxy sample is NIR selected rather than optically-selected 6dFGS surveys <z>=0.05 local universe (cf. 2dFGRS/SDSS <z>=0.1) 6dFGS volume is comparable to the 2dFGRS, but 3x smaller than SDSS Large fibres, so aperture effects are less for 6dFGS than 2dFGRS/SDSS

6dFGS redshift space maps

z < 0.1

The 6dFGS view of the local universe

z-only ly z z + v 1 conto tours rs

• n pairs o

pairs of param paramete ters rs

6dFGS power spectra and constraints

Galaxy power spectrum Velocity power spectrum

2MASS Redshift Survey

All-sky z-survey to Ks=11.25 (limit is 1.5 mag brighter than 6dFGS) 93% complete with z’s from Arecibo, Green Bank and FLWO 1.5m in North and 6dFGS and CTIO in South 2MRS contains 23,000 galaxies and is densest all-sky z-survey to date

cz=6000 km/s

Erdogdu et al., ., 2006, , MNRAS, , 368, , 151

Local density field reconstruction

2MRS de density sity fi field re ld reconstru structio tion by by F Fourie rier-Be r-Besse ssel de l decompo positio sition an and W d Wie iener fi r filte lterin ring

Erdogdu et al., ., 2006, , MNRAS, , 373, , 45

Predicted local velocity field

The linea The linear v r velocity field elocity field in the in the Sup uperg ergala lactic ctic Pla lane a ne as p s pred redicted icted from from the reconstructed the reconstructed 2M 2MRS d RS density field ensity field (a (assum ssuming ing =0.5) 0.5)

Erdogdu et al., ., 2006, , MNRAS, , 373, , 45

Dark energy from geometry

The g The geom eometry of the univ etry of the universe erse ca can b n be m e mea easured sured a at v t very ea ery early rly tim times from es from C CMB, a , and nd a at la t later ter tim times b es by a y a v variety of m riety of method ethods: s: ‘Sta tand ndard rd ca cand ndle le’ prov rovid ided ed by sup y supernov ernovae ‘Sta tand ndard rd sca scale le’ from from gra ravita itationa tional l lensing ensing Grow Growth of d th of density ensity perturb erturbations in clusters tions in clusters ‘Sta tand ndard rd ruler ruler’ of b

• f baryon

ryon acoustic oscilla coustic oscillations (B tions (BAO) O) in the g in the gala laxy d xy distrib istribution ution

The geometry of f the univ iverse is is governed by the equatio ion of f state, knowle ledge of whic ich reveals ls the nature of f the dark energy

The WiggleZ BAO survey

Science goals…

Primary: first z-survey measure of BAO scale at z~1; aim for ~2% precision to constrain w to ~10% and test for evolution Secondary: study properties of star-forming galaxies at z~1

Observing plan…

Targets: 400,000 b~1 galaxies (200,000 with z>0.5) over 1000 deg2 Sample: from GALEX + SDSS/RCS; FUV-NUV colour selects Lyman break at z>0.7; NUV-r selects emission line galaxies Observations: using AAOmega spectrograph with 2dF on AAT Status: ~80,000 redshifts to date; aim to complete in 2009

WiggleZ team…

Australia: Drinkwater, Jurek, Pimbblet (UQ); Blake, Couch, Forbes, Glazebrook, Brough, Jones, Barnes (Swinburne); Woods (UNSW); Croom (Sydney); Pracy (ANU); Colless, Sharp (AAO); USA: Forster, Madore, Martin, Small (GALEX); Canada: Gilbank, Gladders, Yee (RCS2)

Glazebrook et al. , astro-ph/0701876

Sim Simula ulations of tions of Wig iggleZ leZ BAO m O mea easurem surement com ent compared red to m to mod

• del

el pow

• wer sp

er spectrum ectrum exp expect ~2% p ect ~2% precision on sta recision on stand ndard rd ruler sca ruler scale le Mea easure sure H(z (z) and nd DA(z) at t z~0.7, us 0.7, use p priors on riors on M and nd H0 (CMB giv ives es Mh2), reconstruct d , reconstruct density field ensity field 2.7% on .7% on H, 1.8% on 1.8% on DA Eq Equa uation of sta tion of state p te precision recision 10% on 0% on w0 (sim (simila ilar to r to SNe e surv urveys b eys but ut com complem lementa entary in ha ry in having ing a a d different m ifferent method ethod & d & different ifferent deg egenera eneracies cies)

Monte Carlo average data — Model power spectrum

BAO precision and constraints on w

WiggleZ fields and target selection

Total su tal surve rvey are area o a of ~1000deg2, m made ade u up

• f 7

7 e equ quato atorial fi rial fields, lds, eac ach o

• f 1

100-2

• 200 de

deg2 (> (>9º o º on a side a side, > , >2-3

• 3x

BA BAO sc scale ale at z> at z>0.5 .5) Targe argets se ts sele lecte ted u d usin sing combin binatio ation o

• f U

UV (G (GALEX) an ) and o d optic ptical al (S (SDSS/R /RCS2) ) colo lours rs Sele lectio tion c crite riteria pic ria pick emissio ission-lin

• line galax

galaxie ies at at z~0.7 .7 (> (>200 o

• f th

the ~400 targe targets pe ts per de r deg2) Allo llocate ated 2 d 220 n nigh ights ts

• n A

AAT o

• ve

ver 2 r 2006-9

• 9

UV-optical selection criteria

Galax alaxie ies w s with ith NUV < < 2 22.8 .8 an and 20.0 .0 < < r < r < 2 22.5 .5 FUV-N

• NUV >

>1 o

• r

no F FUV de dete tectio tion z > 0 0.5 .5 NUV-r

• r < 2

2 blu blue star-f star-form rmin ing galax galaxie ies, s, stro trong emissio ission lin lines g-r/r-i c g-r/r-i colo lour r cut re redu duces n s numbe ber

• f z<0.5

.5 galax galaxie ies GALEX-S

• SDSS

ban ands ds matc atch no F FUV x ELGs

Model colours 0<z<1.5 .5 LBG SB Im Scd Sbc E/S0

Emissio ission-lin

• line galax

galaxie ies m s margin arginally ally pre preferre rred to d to lu lumin inous re s red galax d galaxie ies: bias f s: bias fac acto tor sm smalle aller bu r but e t easie asier to r to re redsh dshif ift (sh t (shorte rter e r expo posu sure res, s, more re ro robu bust in st in po poor c r conditio ditions) s)

Status of WiggleZ survey

2dFGRS // SDSS SDSS LRGs 2SLAQ LRGs

Wiggle iggleZ surve rvey

Fin inal l expected numbers…

~350,000 sp ~350,000 spectra ectra ~210 ~210,000 000 red edshifts shifts ~160,000 g ~160,000 gala laxies xies at z>0.5 t z>0.5

Redshift ift success rate 60% Tunin ing sele lectio ion crit iteria ia, fractio ion at z>0.5 75% Fractio ion of f sample le at z>0.5 45% Reaches z~1 in in 1–hour exp. (cf. z~0.1 fo for 2dFGRS) due to ELG sele lectio ion & effi fficie iency of AAOmega spectrograph

Small-scale clustering

Prelim relimina inary clustering ry clustering m mea easurem surement strong ent stronger tha er than a n assum ssumed ed… Prop roposa

• sal w

l was 400 red s 400 redshifts/d shifts/deg eg2 at z>0.5 for sa t z>0.5 for sample w le with ith b=1 =1.0 Clustering lustering leng length now th now m mea easured sured to b to be 6 e 6 Mpc/h c/h b=1 =1.4 Eq Equiv uivalent surv lent survey for ey for b=1 =1.4 is 200 red 4 is 200 redshifts/d shifts/deg eg2 at z>0.5 t z>0.5 Thus the rev Thus the revised ised ta targ rget is a et is a surv survey of ey of 200,000 z>0.5 g 00,000 z>0.5 gala laxies xies Hig Higher b her bia ias therefore la s therefore larg rgely com ely compensa ensates for low tes for lower efficiency er efficiency

FastSound survey

Proposed z>1 BAO survey using FMOS/Subaru NIR spectroscopy…

FMOS: 400-fibre J+H OH-suppressed NIR spect., commissioning in Feb 08 ~600,000 H galaxies in ‘redshift desert’ at z~1.0–1.7 over ~300 deg2 (~1 Gpc3) O(100) nights on Subaru Unique redshift range for BAO survey, good precision, lots of ancillary science Japan/UK/Australia team of 40+ people

Totani et al., 2006, in Co Cosmology with wide-fi field photometric and spectroscopic galaxy surveys

(w (with ith A AP te P test) st)

WFMOS survey

Wide-Field Multi-Object Spectrograph for an 8-m telescope (Subaru/Gemini)

1.5 degree field 4000 optical fibres 5 years to build

Survey of >1,000,000 z~1 galaxies to measure BAO

Survey takes ~3 years Combined with CMB / SNe / lensing methods, could achieve precision of w0~few% & w1~10% Also possible z~3 survey

Colless (2005) & Glazebrook (2005), , both in Probin ing the Dark Univ iverse wit ith Subaru and Gemin ini, http:/ ://www.noao.edu/meetings/subaru

Once and future galaxy surveys

Wide-field spectroscopy and redshift surveys will continue to be powerful tools for large-scale structure and cosmology The combined 6dF redshift + velocity survey will better constrain fundamental parameters (such as and rg) and so provide new insights on the relative distributions of luminous and dark matter Current (WiggleZ) and future (FASTsound, WFMOS) redshift surveys will trace the evolution of galaxies & large-scale structure, measuring precisely the evolving geometry of the universe Combined with CMB, SNe and weak lensing, BAO surveys will determine the evolution of the equation of state with few-% precision and strongly constrain the nature of the dark energy Future ELT surveys will map the 3D distribution of baryons down to galaxy scales out to the epoch of formation of the first galaxies