Publications (3)0 Total impact
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ABSTRACT: The nature of the dwarf galaxy population as a function of location in the cluster and within different environments is investigated. We have previously described the results of a search for low surface brightness objects in data drawn from an East-West strip of the Virgo cluster (Sabatini et al., 2003) and have compared this to a large area strip outside of the cluster (Roberts et al., 2004). In this talk I compare the East-West data (sampling sub-cluster A and outward) to new data along a North-South cluster strip that samples a different region (part of sub-cluster A, and the N,M clouds) and with data obtained for the Ursa Major cluster and fields around the spiral galaxy M101. The sample of dwarf galaxies in different environments is obtained from uniform datasets that reach central surface brightness values of ~26 B mag/arcsec^2 and an apparent B magnitude of 21 (M_B=-10 for a Virgo Cluster distance of 16 Mpc). We discuss and interpret our results on the properties and distribution of dwarf low surface brightness galaxies in the context of variuos physical processes that are thought to act on galaxies as they form and evolve. Comment: 10 pages, 3 figures, to appear in "Dark Galaxies and Lost Baryons", IAU244 conference proceedings
07/2007;
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ABSTRACT: The widely varying dwarf galaxy counts in different environments provide a strong challenge to standard hierarchical clustering models. The luminosity function is not universal, but seems to be strongly dependent upon environment. In this paper we describe an automated procedure for detecting and measuring very low surface brightness (LSB) features in deep CCD data. We apply this procedure to large area CCD survey fields of the Virgo cluster. We show that there are many more faint ($-10 \geq M_{B} \geq -14$) low surface brightness galaxies than what would be predicted from extrapolation of the Virgo cluster catalogue luminosity function. Over our limited range of measurement the faint end slope of the luminosity function becomes $\alpha=- 1.6$. The luminosity function is flatter in the inner regions of the cluster than it is in the outer regions. Although these galaxies contribute a small fraction of the total stellar light of the cluster, they may contribute significantly to the mass in galaxies if they have large mass-to-light ratios similar to those recently measured for Local Group dwarf galaxies. Comment: 12 pages, 14 figures (fig 4,6 are poor quality for size reasons). Accepted for publication in MNRAS
01/2003;
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ABSTRACT: We have developed a specific approach devoted to the detection of low surface brightness galaxies on astronomical images. We use a multi-scale detection, we take into account sources of incompleteness and check selection functions both analytically and with simulations. We give a summary of the main points and some examples. Notwithstanding bottlenecks from huge data flows, we also plan to exploit a GRID approach to this problem because several different regions of the sky (images) can be treated separately but identi-cally.
