1. Diffuse Light in Galaxy Groups Nieves D. Castro-Rodríguez 1, J. Alfonso L. Aguerri 1, Magda Arnaboldi 2, Ortwin Gerhard 3 1 Instituto de Astrofísica de Canarias 2 Osservatorio Astronomico di Pino Torinese 3 Astronomisches Institut der Universitat Basel Gdansk 2005 Gdansk 2005

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

3. Diffuse Light: Coma Cluster (Zwicky, 1951) as an excess of light among galaxies. 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 (  B =28 mag arcsec -2 ). Its nature and content has been a mistery during decades due to its low surface brightness (  B =28 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). 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) 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. 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.

4. 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). 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: Fornax: (Theuns & Warren 1997) Studied Core Fields In Virgo Cluster Aguerri et al. (2005)

5. 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. 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. 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).

6. OIII filter and B/V (on- off band technique) OIII filter and B/V (on- off band technique) Contaminants: Contaminants: HII regions in the cluster HII regions in the cluster [OII] emitters at Z~0.34 [OII] emitters at Z~0.34 Ly  emitters at z~3.1 Ly  emitters at z~3.1 Arnaboldi et al. 2002 For details: M. Arnaboldi (previous talk) Planetary Nebulae Method:

7. Leo Group: HI emission ring discovered by Schneider et al. 1983, and the localization of our initial candidates Color Magnitude Diagram There are 29 candidates (Castro-Rodríguez et al. 2003)

8. *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) (Ciardullo et al. 2002) Luminosity Function (LF): 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.

9. Luminosity function of field Ly  emitters at z~3.1 In our effective volume (Castro-Rodríguez et al. 2003) : Continuous line is the expected LF of the Ly  population at z~3.1 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) Background Contaminants -------------- Blank Field Upper limit of the diffuse light in Leo: < 1.6%

10. SpectroscopicConfirmation: 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.

11. HCG44: B band image of HGC 44 from INT Telescope (La Palma, Spain) Color Magnitude Diagram, following the PNe method (Arnaboldi et al. 2002) There are 12 candidates. Aguerri et al. 2005 Hickson Group with high HI deficiency (Verdes-Montenegro et al. (2001))

12. 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  Backgroundgalaxies!!!! Upper limit of the diffuse light in HCG: < 0.24%

13. Conclusions: We have study the IGL in two galaxy groups: Leo and HGC44. 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. 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 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. 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. 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 earthly substance. -- Its presence alone reveals the marvelous splendor of the kingdoms of the world. (Novalis, Friedrich von Hardenberg, "Hymns to the Night" )