WFMOS• KAOS concept identified via the

Gemini Aspen Process and completed a Feasibility Study (Barden et al.)

• Proposed MOS on Subaru via an international collaboration of Gemini and Subaru

• 1.5deg FOV with 4500 fibres feeding 10 low-res spectrographs and 1 high-res spectrograph

• First-light in 2012• ~20000 spectra a night (2dfGRS at

z~1 in ~10 nights)• DE science, Galactic archeology,

galaxy formation studies and lots of ancillary science from database

• Concept Design phase (2 teams) with funding decision next year?

SUBARUMatthew Colless & Sam Barden

WFMOS baselineTop-level design performance guidelines for WFMOS

Wavelength range: 0.39–1.0µm Field of view: ~1.5deg diameterSpectral resolution: R ~ 1000–30,000 (or 40,000)Simultaneous targets: 4000 - 5000

A bit of history…. WFMOS was a proposed second-generation Gemini instrument

that emerged from the ‘Aspen’ process• Before that, it was the KAOS conceptual instrument

http://www.noao.edu/kaos/• Originally for Gemini, sharing of Gemini/Subaru resources was

recognized in 2004 WFMOS underwent a feasibility study (Barden et al. 2005;

Bassett, Nichol & Eisenstein 2006), completed in March 2005. Fully reviewed and recommended WFMOS move to full concept design review

• Subaru/Gemini DE meeting in Hawaii in November 2005 (over 80 participants from Japan, UK, US, Australia, Canada). Recent GA science meeting.

• Two teams have formed and submitted proposals for WFMOS Concept Design; To start in earnest in 2007

• PPARC Council “commitment of up to $18M for the UK share of the Gemini 'Aspen' programme, the full commitment being contingent on the Wide Field Multi Object Spectrograph (WFMOS) instrument proceeding”.

Baryon Acoustic Oscillation

• Gravity squeezes the gas, pressure pushes back! They oscillate

•When the Universe cools below 3000K these sound waves are frozen in

Courtesy of Wayne Hu

STANDARD RULER

•4.7% measurement4.7% measurement of the distance to z=0.35 (effective redshift of LRGs)

•3.7% measurement3.7% measurement of relative distance to z=0.35 and the CMB (most robust measurement)

•Assuming w=-1, in conjunction with the WMAP & Tegmark et al. (2004), the geometry of the Universe is flat Universe is flat to 1%to 1%

All this from a 3detection!

KAOS purple book (Seo, Eisenstein, Blake, Glazebrook)

WFMOS will measure w to <4% and dw/dz to <15%

DE ScienceMeasure BAO at z~1 and z~3 to determine w(z)

DE Physics

DGPLCDM

7 difference

Yamamoto et al. 2006

WFMOS LegacyFacility instrument

• Galaxy Evolution: Every galaxy in Coma (Mr < -11)• IGM and Quasars: Simultaneously observing

QSOs and galaxies in the same fields• Calibrate photo-z’s: LSST and DES require >105

unbiased redshifts

z range R limit (AB)

Volume (h-

1 Gpc)Area (sq

degs)Number Nights

0.5 - 1.3 22.7 4 2000 2000000 100

2.3 - 3.3 24.5 1 300 600000 100

GalaxyArcheology

400000 400

(Glazebrook et al. 2005)

• Few thousand z~1 SNe detected via their spectroscopy

• Alcock-Paczsynki test (Yamamoto et al. 2004, Matsubara 2004)

• High-z cluster counts (Newman et al. 2002)

• Reciprocity relation dA/dL = (1+z)2

(Bassett & Kunz 2004)

WFMOS LegacyArchival science

Conclusion With WiggleZ, FastSound, WFMOS can deliver tight constraints

on dw/dz (testing DE beyond w=constant & modified gravity) WFMOS is “alive and kicking” Concept Design teams eager to

begin hard work of finalizing the design of science and instrument

Challenges ahead include: What targets? HSC+WFMOS looks attractive (SDSS at z~1) Cost! Clear statement from agencies helps morale. Teams

will scrutinize costs. Highly successful science meetings (lots of goodwill

and students!)