nikos nikoloudakis and t.shanks, r.sharples 9 th hellenic astronomical conference athens, greece...

Nikos Nikoloudakis

and T.Shanks, R.Sharples

9th Hellenic Astronomical Conference Athens, Greece

September 20-24, 2009

4 cloned spectrographs at Calar Alto 3.5 m prime focus

4 x 4k x 4k detectors with 15 µm (0.45) pixel 4000 MOS slits simultaneously over a 1°field Spectral resolution 10 Å (R~600) with 1.5 slit Wavelength bands: 4200-5200Å, 5200-7200Å, 7200-

9200Å

OBSERVING CAPABILITIES with 5200-7200Å

25000 galaxy redshifts/night for z up to 0.7 → 1.5 hrs exposure → ~ 5-6 million galaxy spectra in 200 nights → 1000-2000 deg² sky area

9th Hellenic Astronomical Conference

Nikos Nikoloudakis 21/09/2009

Observational Cosmology via galaxy redshift surveys at z~0.7 → LRGs (i<21) ELGs (i<22)

Evolution of halo masses and galaxies to z~0.5 Gravitational growth rate via z-space distortion to

z~0.7 Measuring the scale of BAO at 0.5 < z < 3

Lyman Break Galaxy redshift survey at z~3

Rich galaxy cluster survey

Photo-z calibration for gravitational lensing

Galactic Archaeology



XMS - a further stepXMS - a further step

XMS



Galaxy sky densitiesGalaxy sky densities

i<20 all galaxies ~2500deg-2

21<i<22 all galaxies ~9000deg-2

i<21 z~0.5 em+absn galaxies ~5000deg-2

21<i<22 z~0.7 OII em galaxies ~5000deg-2

2dFGRS in 5% of the observing time at 6x bigger z and ~4mag fainter!!!



i<22 galaxy emission line z from OII 3727Å at S/N>6 in 1.5hr exposure in ~ 1.´´5 seeing

i<21 galaxy absorption line z at continuum S/N>4 in 1.5hr exposure in ~ 1.´´5 seeing

XMS Imaging Base Pan-STARRS 3π reaches i~22 (SDSS only i~20) SDSS stripe 82, PAU and ultimately LSST.


Nikos Nikoloudakis

Tests of survey feasibility



MOSCA Instrument 3.5-m Cassegrain focus at Calar Alto FOV 10 x 8 arcmin2

resolution ~ 28Å ~ 70 slits/ mask William Herschel Deep Field on 12/08/2008

LRGs i<21 ELGs i<22 1 mask/ 2hrs 2 masks/ 1 hr Green -250 grism

Seeing 1-1.5arcsec / transparency oftenly poor Technical problems on 1hr masks – half spectra



z = 0.95

z = 0.77



z = 0.62

z = 0.73



WHDF redshift distributionWHDF redshift distribution

ELG66% successful

z ~ 0.75

LRG 58% ( only 17

LRGs on MOSCA fields)

z ~ 0.68

Galaxies were preselected by photo-z to have

0.4 < z < 0.8



Test z success rate at 5200-7200Test z success rate at 5200-7200ÅÅ

Double-blind test using 267GAMA spectra (JAP)

89% success for 0.4<z<0.8

Worse when OII and CaII H&K break outside range

q=4 redq=3 blueq≤2 green



Cosmology with XMSCosmology with XMS

Measuring the scale of BAO

Measuring the gravitational growth rate



Using CMB data we can determine precisely the physical length scale of BAO.

Combining apparent size + known physical sizes :

→ angular diameter distance dA → Hubble parameter H(z)

Better constraints in w= p/ρ

Identification of systematics created by non-linearity in P(K)

→ standard ruler



→ oscillation in the power spectrum P(k) → spike in the two point spatial galaxy –

galaxy correlation function ξ

The BAO signature has been detected in the local universe:1. 2dFGRS of 250000 z~0.1 galaxies ( Cole et al.

2005)2. SDSS galaxy samples of 75000 z~0.35 LRGs ( Eisenstein et al. 2005)



Measurement Galaxy clustering z-space distortions

Test of Einstein’s gravity theory independently of

geometrical tests using standard candles and rods Estimator of halo masses M/L galaxy groups haloes in CDM models



This quantity can measure survey efficiency for detecting BAO, Gravitational Growth Rate and relative quantities for clustering estimations.

Feldman et al. 1994

The shot noise of the power spectrum must be reduced below the irreducible component due

to sampling variance. Errors on P(k) go as 1/sqrt(Veff(k)).



XMS Survey Effective VolumeXMS Survey Effective Volume

WiggleZ

XMSGES

XMS Total

XMS GES wins at small scales

+20x more halo members than BOSS

XMS Survey remains competitive with BOSS at BAO scales

WiggleZ

XMS offers order of magnitude improvement in MOS multiplex over previous spectrographs (4004000)

Push the limits to fainter surveys with bigger volume

LRG+ELG tracers in same volume Multiple science cases!

XMS is competitive for BAO at scales 40-300 Mpc XMS is more competitive for z-space distortions

at smaller scales.

BAO scale competitive with BOSS Gravitational Growth Rate beats BOSS



OverviewOverview



White, Song/&Percival2008



nikos nikoloudakis and t.shanks, r.sharples 9 th hellenic astronomical conference athens, greece...

Documents

cdm models nikos nikoloudakis

successful z

galaxy spectra

galaxy redshiftsnight

sdss galaxy samplesof

galaxy redshift surveys

galaxy sky densitiesii6

galaxy groups haloes