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EnglishWe investigate whether the spectral-type of a locally dominant (most luminous) galaxy can be used to select sets of galaxies that are physically associated (groups). We assume that passive dominants trace a group-like potential, and SF-dominants a field-like environment. The group sample includes 988 groups selected in the 2dFGRS applying a maximum magnitude difference criterion. We find that the average number of passive galaxies associated to a dominant is larger when the dominant is passive, a result supporting our assumption that galaxy associations around a passive dominant are reliable groups. Finally we show that, to reduce the contamination by unbound galaxy associations (SF-dominant), ${rm a}geq 3$ passive-members criterion is more efficient than ${rm a}geq 6$ all-members criterion.
| Titolo: | Dominant galaxies in 2dF groups |
| Autore/i: | KELM, BIRGIT; FOCARDI, PAOLA |
| Autore/i Unibo: | |
| Anno: | 2004 |
| Titolo del libro: | Outskirts of Galaxy Clusters: Intense Life in the Suburbs, IAU Coll. 195 |
| Pagina iniziale: | 456 |
| Pagina finale: | 458 |
| Abstract: | We investigate whether the spectral-type of a locally dominant (most luminous) galaxy can be used to select sets of galaxies that are physically associated (groups). We assume that passive dominants trace a group-like potential, and SF-dominants a field-like environment. The group sample includes 988 groups selected in the 2dFGRS applying a maximum magnitude difference criterion. We find that the average number of passive galaxies associated to a dominant is larger when the dominant is passive, a result supporting our assumption that galaxy associations around a passive dominant are reliable groups. Finally we show that, to reduce the contamination by unbound galaxy associations (SF-dominant), ${rm a}geq 3$ passive-members criterion is more efficient than ${rm a}geq 6$ all-members criterion. |
| Data prodotto definitivo in UGOV: | 5-ott-2005 |
| Appare nelle tipologie: | 4.01 Contributo in Atti di convegno |
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