Bibcode
Filho, M. E.; Sánchez Almeida, J.; Muñoz-Tuñón, C.; Nuza, S. E.; Kitaura, F.; Heß, S.
Bibliographical reference
The Astrophysical Journal, Volume 802, Issue 2, article id. 82, 16 pp. (2015).
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4
2015
Journal
Citations
35
Refereed citations
32
Description
We have analyzed bibliographical observational data and theoretical
predictions, in order to probe the environment in which extremely
metal-poor dwarf galaxies (XMPs) reside. We have assessed the H i
component and its relation to the optical galaxy, the cosmic web type
(voids, sheets, filaments and knots), the overdensity parameter and
analyzed the nearest galaxy neighbors. The aim is to understand the role
of interactions and cosmological accretion flows in the XMP
observational properties, particularly the triggering and feeding of the
star formation. We find that XMPs behave similarly to Blue Compact
Dwarfs; they preferably populate low-density environments in the local
universe: ∼60% occupy underdense regions, and ∼75% reside in
voids and sheets. This is more extreme than the distribution of
irregular galaxies, and in contrast to those regions preferred by
elliptical galaxies (knots and filaments). We further find results
consistent with previous observations; while the environment does
determine the fraction of a certain galaxy type, it does not determine
the overall observational properties. With the exception of five
documented cases (four sources with companions and one recent merger),
XMPs do not generally show signatures of major mergers and interactions;
we find only one XMP with a companion galaxy within a distance of 100
kpc, and the H i gas in XMPs is typically well-behaved, demonstrating
asymmetries mostly in the outskirts. We conclude that metal-poor
accretion flows may be driving the XMP evolution. Such cosmological
accretion could explain all the major XMP observational properties:
isolation, lack of interaction/merger signatures, asymmetric optical
morphology, large amounts of unsettled, metal-poor H i gas, metallicity
inhomogeneities, and large specific star formation.
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Casiana
Muñoz Tuñón