Dusty Galaxies in Protoclusters Dave Clements, Josh Greenslade, - - PowerPoint PPT Presentation

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Dusty Galaxies in Protoclusters Dave Clements, Josh Greenslade, - - PowerPoint PPT Presentation

Jan 21, 2023 22 likes •236 views

Dusty Galaxies in Protoclusters Dave Clements, Josh Greenslade, Tai-an Cheng, Imperial College London The HerMES & H-ATLAS Consortia The Planck Collaboration Massive Cluster Galaxy Formation How do high mass (>10 11 M sun )

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SLIDE 1

Dusty Galaxies in Protoclusters


Dave Clements, Josh Greenslade, Tai-an Cheng, Imperial College London The HerMES & H-ATLAS Consortia The Planck Collaboration

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SLIDE 2

Massive Cluster Galaxy Formation

  • How do high mass (>1011Msun) cluster galaxies form?
  • Mostly massive old, red & dead ellipticals
  • Colours imply they formed at high redshift but high

z clusters difficult to find

  • The few known high z (z=2-5) protoclusters (Casey,

2016) each host several massive starburst galaxies

  • How to find more? How do they work?
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SLIDE 3

Dusty Protoclusters

Two protoclusters at z=2.1 and z=2.47 in

  • COSMOS. Red & blue dots are DSFGs

(Casey et al 2015, Yuen et al. 2014)

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SLIDE 4

Models: Granato et al.

Forming cluster at z=2: luminosity in SPIRE bands

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SLIDE 5

Far-IR Surveys

  • Far-IR surveys excellent at finding high SFR source

but need large area: Herschel &/or Planck HerMES & H-ATLAS fields

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SLIDE 6

Herschel-Planck Approach

  • Look at Herschel images of Planck sources in

~1000 sq. deg. covered by large surveys

Known Sources: 58%

Largely known local galaxies such as NGC5012 shown here. Identifjable by resolved emission in Herschel and cross matches to catalogues.

Galactic Cirrus: 24%

Identifjable through extended emission in Herschel & IRAS, absence

  • f known cataloged sources.

Protocluster Candidates: 14%

Overdensities of Herschel sources, no extended emission, no extant identifjcation, no extended IRAS

  • emission. 59 of these are found, de-

tails in Greenslade et al., in prep Plus 3% strong lensing candidates and 1% stars.

Clements et al., 2014 Greenslade et al., in prep

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SLIDE 7

Herschel-Planck Followup

  • SCUBA2 (& LABOCA)

data extends SED from 250 to 850 microns

  • Allows photo-z estimate
  • Helps cross IDs

Planck Herschel SCUBA2

SCUBA2, SMA, Radio, Optic

Clements et al., 2016

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SLIDE 8

Clements et al., 2016

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SLIDE 9

Cheng et al. in prep

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SLIDE 10

Cheng et al. in prep

I J H Ks 3.6μm 4.5μm

29/30

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SLIDE 11

Cheng et al. in prep

I J H Ks 3.6μm 4.5μm

29/30

Cheng et al. in prep

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SLIDE 12

Bootes Clump z~2.27

  • Planck ERCSC source, overdensity in Herschel,

photo-z peak at z=2.27

Clements et al., 2014

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SLIDE 13

Herschel Clump Source colours

Greenslade et al. in prep

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SLIDE 14

Suggests this approach is sensitive to at least some warmer, lower z clusters

Greenslade et al. in prep

Planck Colours

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SLIDE 15

Herschel-Planck Protoclusters

  • 59 candidate dusty protoclusters in Herschel surveys
  • Compare to Granato et al. (2015) physical models of cluster galaxy formation
  • Groups of starbursts predicted in clusters but not as bright or

numerous as we find

  • But overall counts do match Negrello et al. (in prep) analytic model

Granato et al., 2015

100 101 102 103 104

F (mJy)

10−4 10−2 100 102 104 106 108 1010

dN/d log F (sr−1)

545GHz

Planck (PCXXXIX) simulations (S/N> 5) un-lensed proto-spheroids proto-clusters

Negrello et al., in prep

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SLIDE 16

How do these clumps work?

2 4 6

Redshift

5 10 15 20 25 30 35

Number of Sources

CLS UDS Planck over-densities

Mackenzie et al., submitted: 61 candidates, 51 confirmed (rest are lenses)

  • Submm confirmation:

improves photo-z & helps identification

  • Detection of non-SB

cluster members

  • Cross-IDs for DSFGs
  • Spectroscopic redshifts
  • Deeper studies of Lya

detected clusters

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SLIDE 17
  • Is rapid star formation

restricted to the luminous DSFGs, as a result of merging?

  • Or are all galaxies in a

protocluster forming stars at an increased rate eg. through cold gas infall? Casey, 2016

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SLIDE 18

Radio Followup

SPIRE 250 greyscale with ATCA 5GHz contours. Source IDs & unexpected FR1. VLA data coming 6GHz flux prediction for 16mJy 350 micron source from radio-FIR relation

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SLIDE 19

Current Status

  • Planck source identification yields plentiful candidate

high z star bursting cluster candidates

  • Potentially revealing a brief but formative phase of

cluster evolution

  • SCUBA2 & SPIRE followup constrains redshifts &
  • ther properties but spectroscopy needed and

underlying cluster galaxies need to be studied as well

  • Other approaches (eg. looking at optically selected

high z cluster candidates) also promising

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SLIDE 20

What Next?: SPICA

  • Proposed ESA-

JAXA mission for mid to far-IR spectroscopy

  • 2.5m diameter,

telescope cooled to 8K

  • Two instruments:

mid-IR & far-IR

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SLIDE 21

Positive AGN Feedback?

  • z=3.65 QSO
  • Green is 8GHz

radio, red is 850micron dust

  • CO 1-0 & higher
  • res. 20GHz radio

coming

  • Jet induced star

formation??