Diffuse Light in a cluster at z=2 Paola Dimauro, Emanuele Daddi, - - PowerPoint PPT Presentation

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Diffuse Light in a cluster at z=2 Paola Dimauro, Emanuele Daddi, - - PowerPoint PPT Presentation

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Diffuse Light in a cluster at z=2 Paola Dimauro, Emanuele Daddi, Veronica Strazzullo , Raphael Gobat, Marc Huertas-Company Paris - 7 October 2016 What is the diffuse light? Stars stripped from the outer region of the galaxies during the

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Paola Dimauro, Emanuele Daddi, Veronica Strazzullo , Raphael Gobat, Marc Huertas-Company

Diffuse Light in a cluster at z=2

Paris - 7 October 2016

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What is the diffuse light?

Coma cluster

Stars stripped from the outer region of the galaxies during the cluster’s formation The properties of the ICL in clusters, particularly the fractional luminosity, radial light profile, and presence of substructure, may hold important clues about the accretion history and dynamical evolution of galaxy clusters.

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What is the Intra-Cluster Light ( ICL )

Formation mechanism:

  • Shredding of dwarf galaxies
  • Tidal stripping
  • In situ star formation
  • Merging

De Maio 2014,Krick 2007 Density

  • Stripping process : high

mass clusters have more ICL then low ones

  • Merging : no correlation with

the mass

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Diffuse light

Formation mechanism:

  • Shredding of dwarf galaxies
  • Tidal stripping
  • In situ star formation
  • Merging

De Maio 2014,Krick 2007 When? -> Color

  • Red : Stars are stripped early

and then evolve passively towards red color

  • Same color of the galaxies :

remnant from ongoing interaction

  • Blue : recent star formation

activity has made

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Diffuse light

Formation mechanism:

  • Shredding of dwarf galaxies
  • Tidal stripping
  • In situ star formation
  • Merging

De Maio 2014,Krick 2007 When? -> Spatial distribution

  • the morphology of the ICL

changes as the cluster evolve: at the beginning is characterized by tidal features then they tend to mix to form a more diffuse halo.

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From the letterature …

  • 0.8 < z < 1.2 diffuse light : 1-4% (Burke et all 2012)
  • Krick & Bernstein 2007

z < 0.4 diffuse light fraction : 6-22 % (Krick 2007)

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From the letterature …

  • ICL amount increase as cluster evolves ~ 10-15 % at z=0
  • Semi-analitic model z<=1 : ICL vary between 5-25 % (Contini 2014)

time time time f_icl

simulation

merger

  • The formation of the ICL has no preferred redshift and is a cumulative

power-law process up to redshift z = 0. (Murante et all 2007)

(Rudick 2006)

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Goal of this work

CL J1449+0856

Instrument: HST WFC3 Bands: F105, F140

z = 1.99

Mtot ' 6 ⇤ 1013 M

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First step : Optimal background removing What is new?

  • Remove contamination / gradient from bright sources
  • Preserve the diffuse halo of low surface brightness : ICL

The solution

Dynamical masking to cover wide range of size

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Mask Background map First step : Optimal background removing

The background map is estimated using Sextractor. In the masked region is interpolated from the neighboring region

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Before After First step : Optimal background removing

The gradient are removed but the halo are preserved

Filter : F140

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The models are done using Galfit (Peng et al 2010) Second step : Fit the models

Filter : F140

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Σ(r) = Σ0(1 − [ r rout ]2−β)α

Ferrer profile Sersic profile

Σ(r) = Σe[−k( r re )

1 n − 1]

Second step : Fit the models

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Galfit model Residual map

Filter : F140

Third step : Diffuse light, model and result

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Original image ICL

F105 : F140 :

mag = 24.00 Third step : Diffuse light, model and result

Filter : F140

ICL model mag = 23.00

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Is it a O III emission associated to the Lya nebula ?

Valentino 2016

Test … mag = 25.9

Filter : F140

mag = 23.00

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g-band : r-band :

mag = 20.52 mag = 18.94 z~0.49

Instrument: Large Binocular Telescope Bands: r,g

Results :

Dimauro,Giallongo in prep

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Results : Color

Preliminary results

z = 0.49 z = 1.99

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Results : Color ICL

Red: Stars are stripped early and then evolve passively towards red color Krick 2006 Same color of the galaxies : remnant from ongoing interaction Blue : recent star formation activity has made

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Results : Absolute magnitude

Preliminary results

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Results : Absolute magnitude

Preliminary results

2 Z

  • Z

0.5 Z

  • - BC03

_. MC05

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Results : Mass ratio

Preliminary results

M⇤ ' 0.5 1 ⇤ 1012M

3- 10 %

MICL

M∗

'

MICL ' 3 5 ⇤ 1010 M Higher than what is predicted by the simulation

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Conclusion

Measure the diffuse light in a cluster at z~2 :

  • The color is more blu than the red sequence
  • is brighter than the diffuse light found in cluster at low-z
  • the mass fraction is 3-10 % higher then what is predicted

by the simulation

  • Our result is in agreement on what is found in other clusters

The fraction of diffuse light increase with the redshift and it depend on the mass assembly story of the cluster and

  • n the different proper.
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Conclusion

  • Absolute magnitude : brighter than low z
  • Mass ratio : almost the same
  • Color : bluer than the red-sequence of the cluster at

z~1.99

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mag=26.2

Zanella 2015

from the letterature …

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F105

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F105