Diffuse Light in Galaxy Groups

1
Diffuse Light in Galaxy Groups

• Nieves D. Castro-Rodríguez1, J. Alfonso L.
  Aguerri1, Magda Arnaboldi2, Ortwin Gerhard3
• 1Instituto de Astrofísica de Canarias
• 2Osservatorio Astronomico di Pino Torinese
• 3Astronomisches Institut der Universitat Basel
• Gdansk 2005

2
Outline

• Diffuse Light
• General characteristics
• Detection of diffuse light
• Clusters and groups
• Leo Group
• HGC 44
• Conclusions

3
Diffuse Light

• Coma Cluster (Zwicky, 1951) as an excess of light
  among galaxies.
• Its nature and content has been a mistery during
  decades due to its low surface brightness (?B28
  mag arcsec-2).
• It has been detected by different tracers
  Globular clusters (West et al. 1995, Jordán et
  al. 2003), SNe (Gal-Yam et al. 2003), RGB
  (Ferguson et al. 1998), ICPNe (Arnaboldi et al.
  1998).
• Nature Harassment (Moore
  et al. 1996)
• Simulations tell us that DL depends on the mass
  of the cluster (Murante et al. 2004). The more
  massive clusters have the largest fraction of
  diffuse light.

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Virgo Cluster

• Virgo Diffuse light in the Core is clumpy and
  represents about 10 of the total light.
  (Arnaboldi et al. 2002 Aguerri et al. 2005).
• Fornax
• (Theuns Warren 1997)

Studied Core Fields In Virgo Cluster Aguerri et
al. (2005)
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Groups of Galaxies

• Diffuse light fraction less than that seen in
  rich clusters. Observations in M81 group
  (Feldmeier et al. 2003) less than 3 of the
  total stellar luminosity.
• In general, diffuse light in groups of galaxies
  is not deep studied.

Fraction of stellar mass in diffuse light vs.
cluster mass (Murante et al. 2004) .
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Planetary Nebulae Method

• OIII filter and B/V (on-off band technique)
• Contaminants
• HII regions in the cluster
• OII emitters at Z0.34
• Ly? emitters at z3.1

Arnaboldi et al. 2002
For details M. Arnaboldi (previous talk)
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Leo Group
Color Magnitude Diagram There are 29 candidates
(Castro-Rodríguez et al. 2003)
HI emission ring discovered by Schneider et al.
1983, and the localization of our initial
candidates
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Luminosity Function (LF)
Luminosity Function of the selected emission
line candidates in the Leo Field. This LF is
compared with the PNe LF in the Leo
galaxies. PNe as standard candles (Ciardullo et
al. 2002)
The LF of the PNe have been used as distance
indicators in late and early galaxies (Ciardullo
et al. 2002). The bright cut-off of our objects
is 1.2 mag fainter that the PNLF of the main
galaxy in Leo.
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Luminosity function of field Ly? emitters at
z3.1 In our effective volume (Castro-Rodríguez
et al. 2003)
Continuous line is the expected LF of the Ly?
population at z3.1 from Steidel et al. (2000).
Filled dots indicated the Ly? in the
Blank-Field survey by Cowie Hu (1998), and
asterisks are spectroscopically confirmed Ly?
emitters from Kudritzki et al. (2000)
Upper limit of the diffuse light in Leo Background Contaminants --------------
Blank Field
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Spectroscopic Confirmation
Two-Dimensional spectra of some emission line
candidates with the VLT
One-Dimensional spectra of two IGPNe candidates.
The Ly? emission is visible in both objects.
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HCG44
B band image of HGC 44 from INT Telescope (La
Palma, Spain)
Aguerri et al. 2005
Hickson Group with high HI deficiency
(Verdes-Montenegro et al. (2001))
Color Magnitude Diagram, following the PNe method
(Arnaboldi et al. 2002) There are 12 candidates.
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LF of the IGPNe photometrical candidates (full
squares). Is also overlaped the LF of the Ly?
objects from Castro-Rodríguez et al. (2003)
Aguerri et al. (2005) Kudritzki et al. (2000)
Ciardullo et al. (2002).
All of the candidates Are compatible with
Ly? Background galaxies!!!!
Upper limit of the diffuse light in HCG 13
Conclusions

• We have study the IGL in two galaxy groups Leo
  and HGC44.
• The emission line objects detected in both groups
  have a LF compatible with Ly? emitters .
• This gives an upper limit of diffuse light in
  those groups of 1-3.
• This number is much smaller than the detected in
  more massive clusters like the core region of
  VIrgo cluster.
• The detected emission line objects can be used
  for background contamination in similar studies.

14
Before all the wondrous shows of the widespread
space around him, what living, sentient thing
loves not the all-joyous light -- with its
colors, its rays and undulations, its gentle
omnipresence in the form of the wakening Day? The
giant-world of the unresting constellations
inhales it as the innermost soul of life, and
floats dancing in its blue flood -- the
sparkling, ever-tranquil stone, the thoughtful,
imbibing plant, and the wild, burning multiform
beast inhales it -- but more than all, the
lordly stranger with the sense-filled eyes, the
swaying walk, and the sweetly closed, melodious
lips. Like a king over earthly nature, it rouses
every force to countless transformations, binds
and unbinds innumerable alliances, hangs its
heavenly form around every earthlysubstance. --
Its presence alone reveals the marvelous splendor
of the kingdoms of the world.  (Novalis,
Friedrich von Hardenberg, "Hymns to the Night" )