Pushing the limits with spectroscopy: High-redshift overdensities - - PowerPoint PPT Presentation

▶
pushing the limits with spectroscopy
SMART_READER_LITE
LIVE PREVIEW

Pushing the limits with spectroscopy: High-redshift overdensities - - PowerPoint PPT Presentation

Dec 10, 2022 129 likes •385 views

Pushing the limits with spectroscopy: High-redshift overdensities at 2<z<6 in zCOSMOS and MUSE-Wide Catrina Diener + Simon Lilly (ETH Zurich), the zCOSMOS team Lutz Wisotzki (AIP Potsdam), the MUSE-Wide team We cant find

slide-1
SLIDE 1

Pushing the limits with spectroscopy: 


High-redshift overdensities at 2<z<6 in zCOSMOS and MUSE-Wide

Catrina Diener +

Simon Lilly (ETH Zurich), the zCOSMOS team
 Lutz Wisotzki (AIP Potsdam), the MUSE-Wide team

slide-2
SLIDE 2

We can’t find proto-clusters using spectroscopy

slide-3
SLIDE 3

Go low redshift - in approach

  • Using spectroscopic redshifts
  • Friends-of-friends type algorithm


Look for proto-groups/cluster rather than groups/clusters

slide-4
SLIDE 4

Go low redshift - in approach

  • Using spectroscopic redshifts
  • Friends-of-friends type algorithm


Look for proto-groups/cluster rather than groups/clusters Better contrast!

slide-5
SLIDE 5

Go low redshift - in approach

  • Using spectroscopic redshifts
  • Friends-of-friends type algorithm


Look for proto-groups/cluster rather than groups/clusters Better contrast! Can probe less “extreme” system But: It is expensive to cover large enough areas

slide-6
SLIDE 6

Proof of principle:

  • zCOSMOS-deep: 2<z<3 with 3500 galaxies
  • MUSE-Wide: 3<z<6 with ~1000 Lya-emitters at completion

Go low redshift - in approach

  • Using spectroscopic redshifts
  • Friends-of-friends type algorithm


Look for proto-groups/cluster rather than groups/clusters Better contrast! Can probe less “extreme” system But: It is expensive to cover large enough areas

slide-7
SLIDE 7

12 14 16 11 13 15 log M, z=0 log M, z=6.2 12 14 16 11 13 15 log M, z=0 log M, z=4.9 12 14 16 11 13 15 log M, z=0 log M, z=3.9 12 14 16 11 13 15 log M, z=0 log M, z=3.1 12 14 16 12 14 16 log M, z=0 log M, z=2.1 12 14 16 12 14 16 log M, z=0 log M, z=1.1 12 14 16 12 14 16 log M, z=0 log M, z=0.5

Why find proto-clusters in first place?

Galaxies in massive haloes at z=high will be in massive haloes at z=0

slide-8
SLIDE 8

13 14 15 16 8 10 12 14 16 log M, z=0 log M, z=6.2 13 14 15 16 8 10 12 14 16 log M, z=0 log M, z=4.9 13 14 15 16 8 10 12 14 16 log M, z=0 log M, z=3.9 13 14 15 16 8 10 12 14 16 log M, z=0 log M, z=3.1 13 14 15 16 8 10 12 14 16 log M, z=0 log M, z=2.1 13 14 15 16 8 10 12 14 16 log M, z=0 log M, z=1.1 13 14 15 16 8 10 12 14 16 log M, z=0 log M, z=0.5

Bad news: the reverse is not true…

Galaxies in z=0 massive group and cluster haloes 
 live not necessarily in massive haloes at higher z

slide-9
SLIDE 9

1 2 3 4 5 6 7 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 redshift F descendants progenitors

We are missing most progenitors of todays clusters…

slide-10
SLIDE 10

1 2 3 4 5 6 7 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 redshift F descendants progenitors

We are missing most progenitors of todays clusters…

This is not helped by focussing on over-densities 
 around high-density tracers (like radio-galaxies)

slide-11
SLIDE 11
  • Part of the zCOSMOS Large Programme 

  • f 600hr at

VLT/VIMOS

  • BzK and ugr selected + magnitude cut in 


B and K band (star-forming galaxies at z>1)

  • 70% sampled area covering 0.6x0.62deg


(From full area of 0.92x0.91deg)

  • 3502 objects with reliable redshifts in 


the range 1.8<z<3

  • ~50% overall sampling and dv=300km/s


1.8 2 2.2 2.4 2.6 2.8 3 10 20 30 40 50 60 70 80 zspec number

  • cf. zCOSMOS-bright, 120km/s, 18’000 objects tp z~1, about 500 groups

witi N>2 (Lilmy et al. 2009, Knobel et al. 2012)

The zCOSMOS-deep survey

slide-12
SLIDE 12
  • Calibrate the group-finding parameters
  • Use mock counterparts of the identified 


structures to make predictions on DM 
 halo distribution and evolution

  • Carefully tune these mock catalogues to

  • bservations: i.e. match number densities, 


redshift errors, selection criteria...

Combined approach: Simulations and observations

Using the Millennium simulation and its publicly available mocks to:

slide-13
SLIDE 13
  • Calibrate the group-finding parameters
  • Use mock counterparts of the identified 


structures to make predictions on DM 
 halo distribution and evolution

  • Carefully tune these mock catalogues to

  • bservations: i.e. match number densities, 


redshift errors, selection criteria... Obvious caveat: 
 Only valid as long as simulations indeed reflect the observations

Combined approach: Simulations and observations

Using the Millennium simulation and its publicly available mocks to:

slide-14
SLIDE 14
  • Automated group-finder using 


the friends-of-friends method

  • Calibrated with mocks
  • Linking lengths: 


dr = 500kpc and 
 dv = 700km/s

  • Requiring N>2

149.8 150 150.2 150.4 150.6 1.8 2 2.2 2.4 2.6 RA DEC

Finding proto-groups applied to zCOSMOS

Yields a catalogue of 42 candidate proto-groups

slide-15
SLIDE 15
  • At redshift of detection: mostly centrals (>90%)
  • 93% will fully or partially assemble by present epoch (z=0)





What does our group-finder detect?

0.5 1 1.5 2 2.5 3 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 <fraction of groups (N=3)> redshift 200 400 600 800 100 200 300 400 500 600 700 vrms [km/s] rrms [kpc] 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 fraction of proto−groups

not assembled partially fully

Assembly process “Success” almost independent 


  • f transverse size…
slide-16
SLIDE 16

Evolution to z=0: Typically group-type haloes

none bright enough too few 
 bright 
 enough too dispersed detectable detected

Fraction of a given halo with respect to 
 all haloes at this mass: Cataloguing a good fraction of todays cluster

z=0 halo mass

slide-17
SLIDE 17

Evolution to z=0: Typically group-type haloes

none bright enough too few 
 bright 
 enough too dispersed detectable detected

Fraction of a given halo with respect to 
 all haloes at this mass: Cataloguing a good fraction of todays cluster

z=0 halo mass

Halo mass distribution at z=0 


  • f structures identified at z~2

General halo mass function

slide-18
SLIDE 18
  • Discovered in a FORS2 run targeting 


known proto-groups

  • 11 spectroscopically confirmed members 


within dr=1.4Mpc and dv=700km/s

  • Overdensity: ~10

Side note: z=2.45 proto-cluster with 11 members

slide-19
SLIDE 19
  • Discovered in a FORS2 run targeting 


known proto-groups

  • 11 spectroscopically confirmed members 


within dr=1.4Mpc and dv=700km/s

  • Overdensity: ~10

− − − − − − − − − − − − − − − −0.2 − − − − −0.2 −0.1 0.1 0.2 −0.2 −0.1 0.1 0.2

Mz=0=1014.9 Msun/h

−

Side note: z=2.45 proto-cluster with 11 members

  • Corresponding z=0 cluster has several

thousands progenitor galaxies at z~2.5

  • Most too faint for FORS2-type spectroscopy,

but within dv=700km/s

  • Diameter of progenitor region is 3-20Mpc,

much bigger than identified proto-cluster

slide-20
SLIDE 20

Work in progress Proceed with caution…

slide-21
SLIDE 21

MUSE-Wide: 1000 Lya-emitters at 3<z<6

Final survey will:

  • Observe ~100 fields at 1h depth
  • Detect several 1000 emission-line

  • bjects from 0<z<6
  • Exploit the multi-wavelength data


to derive galaxy properties

MUSE-Wide (PI L. Wisotzki): Part of MUSE GTO time

  • Covering representative area of sky in with MUSE (1’x1’ FOV)
  • Observing legacy fields (mainly CDFS and COSMOS fields)
slide-22
SLIDE 22

MUSE-Wide: 1000 Lya-emitters at 3<z<6

Final survey will:

  • Observe ~100 fields at 1h depth
  • Detect several 1000 emission-line

  • bjects from 0<z<6
  • Exploit the multi-wavelength data


to derive galaxy properties

MUSE-Wide (PI L. Wisotzki): Part of MUSE GTO time

  • Covering representative area of sky in with MUSE (1’x1’ FOV)
  • Observing legacy fields (mainly CDFS and COSMOS fields)

Current status:

  • About 75 fields observed & reduced
  • Catalogue for first 24 fields 


(22.2arcmin2)

  • Including 237 Lya-emitters
slide-23
SLIDE 23
  • 13 associations with 3-6 members
  • Most prominently a z=4.50 structure 


with 6 members

  • Simulation suggest that ~70% of 


these galaxies end in >1013 Msun haloes 
 (30% even in >1014 Msun) Many properties yet to come, but: 
 Tentatively higher Lya-fluxes (and continuum fluxes) for proto-group galaxies

Proto-groups in MUSE-Wide

Preliminary: 
 Using similar parameters for the FoF algorithm as in zCOSMOS

3 3.5 4 4.5 5 5.5 6 10 20 30 zspec NLAE

slide-24
SLIDE 24
  • 13 associations with 3-6 members
  • Most prominently a z=4.50 structure 


with 6 members

  • Simulation suggest that ~70% of 


these galaxies end in >1013 Msun haloes 
 (30% even in >1014 Msun) The future is bright:

  • Quadruple the sample
  • Calibrate FoF parameters
  • Derived galaxy properties

Proto-groups in MUSE-Wide

Preliminary: 
 Using similar parameters for the FoF algorithm as in zCOSMOS

3 3.5 4 4.5 5 5.5 6 10 20 30 zspec NLAE

slide-25
SLIDE 25

Summary

Application of an automated 
 group-finder to zCOSMOS 
 yielding 42 overdensities; 
 these are mostly proto-groups

0.5 1 1.5 2 2.5 3 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 <fraction of groups (N=3)> redshift

Discovery of z=2.45 
 proto-cluster


With the advent of MUSE spectroscopic proto-group detection can be extended out to z~6

3 3.5 4 4.5 5 5.5 6 10 20 30 zspec NLAE 1 2 3 4 5 6 7 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 redshift F descendants progenitors

Even if finding proto-clusters we only ever sample a small 
 fraction of today’s cluster progenitor galaxies