1,069 research outputs found
Livelihoods and poverty reduction in coastal communities in the Western Region of Ghana: analysis of livelihoods baseline data of the ICFG Program
This report is the result of the livelihoods baseline survey as part of the USAID-funded Integrated Coastal and Fisheries Governance (ICFG) Program for the Western Region of Ghana (Hen Mpoano). The survey aims to provide a baseline for interventions to be implemented as part of the Hen Mpoano project by: 1) Establishing a baseline of the status of livelihoods of households in target communities (assess income levels and sources, seasonality issues, assets, vulnerability); 2) Establishing a simplified nutritional baseline of households in target communities and fish species consumed; 3) Identifying opportunities for livelihood diversification in the target opportunities
Globular cluster formation in the context of galaxy formation and evolution
The formation of globular clusters (GCs) remains one of the main unsolved
problems in star and galaxy formation. The past decades have seen important
progress in constraining the physics of GC formation from a variety of
directions. In this review, we discuss the latest constraints obtained from
studies of present-day GC populations, the formation of young massive clusters
(YMCs) in the local Universe, and the observed, large-scale conditions for star
and cluster formation in high-redshift galaxies. The main conclusion is that
the formation of massive, GC progenitor clusters is restricted to high-pressure
environments similar to those observed at high redshift and at the sites of YMC
formation in the local Universe. However, the correspondingly high gas
densities also lead to efficient cluster disruption by impulsive tidal shocks,
which limits the survival of GCs progenitor clusters. As a result, the
long-term survival of GC progenitor clusters requires them to migrate into the
host galaxy halo on a short time-scale. It is proposed that the necessary
cluster migration is facilitated by the frequent galaxy mergers occurring at
high redshift. We use the available observational and theoretical constraints
to condense the current state of the field into a coherent picture of GC
formation, in which regular star and cluster formation in high-redshift
galaxies naturally leads to the GC populations observed today.Comment: 34 pages, 7 figures, 1 table; invited review published in Classical
and Quantum Gravity, 2014, Volume 31, issue 24, id. 244006, for a focus issue
on Galactic Centres, Eds. Clifford Will and Pau Amaro-Seoane; minor changes
with respect to the submitted versio
The Optical Colors of Giant Elliptical Galaxies and their Metal-Rich Globular Clusters Indicate a Bottom-Heavy Initial Mass Function
We report a systematic and statistically significant offset between the
optical (g-z or B-I) colors of seven massive elliptical galaxies and the mean
colors of their associated massive metal-rich globular clusters (GCs) in the
sense that the parent galaxies are redder by 0.12-0.20 mag at a given
galactocentric distance. However, spectroscopic indices in the blue indicate
that the luminosity-weighted ages and metallicities of such galaxies are equal
to that of their averaged massive metal-rich GCs at a given galactocentric
distance, to within small uncertainties. The observed color differences between
the red GC systems and their parent galaxies cannot be explained by the
presence of multiple stellar generations in massive metal-rich GCs, as the
impact of the latter to the populations' integrated g-z or B-I colors is found
to be negligible. However, we show that this paradox can be explained if the
stellar initial mass function (IMF) in these massive elliptical galaxies was
significantly steeper at subsolar masses than canonical IMFs derived from star
counts in the solar neighborhood, with the GC colors having become bluer due to
dynamical evolution, causing a significant flattening of the stellar MF of the
average surviving GC.Comment: 12 pages (in emulateapj format), incl. 12 figures and 3 tables;
published in The Astrophysical Journa
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