243 research outputs found
Galaxy clusters, type Ia supernovae and the fine structure constant
As is well known, measurements of the Sunyaev-Zeldovich effect can be
combined with observations of the X-ray surface brightness of galaxy clusters
to estimate the angular diameter distance to these structures. In this paper,
we show that this technique depends on the fine structure constant, .
Therefore, if is a time-dependent quantity, e.g., , where is a function of redshift, we argue that current data do
not provide the real angular diameter distance, , to the cluster
but instead . We use this result to
derive constraints on a possible variation of for a class of dilaton
runaway models considering a sample of 25 measurements of in
redshift range and estimates of from
current type Ia supernovae observations. We find no significant indication of
variation of with the present data.Comment: 8 pages, 4 figures, To appear in JCA
Constraints on a possible variation of the fine structure constant from galaxy cluster data
We propose a new method to probe a possible time evolution of the fine
structure constant from X-ray and Sunyaev-Zeldovich measurements of
the gas mass fraction () in galaxy clusters. Taking into account a
direct relation between variations of and violations of the
distance-duality relation, we discuss constraints on for a class of
dilaton runaway models. Although not yet competitive with bounds from high-
quasar absorption systems, our constraints, considering a sample of 29
measurements of , in the redshift interval , provide
an independent estimate of variation at low and intermediate
redshifts. Furthermore, current and planned surveys will provide a larger
amount of data and thus allow to improve the limits on variation
obtained in the present analysis.Comment: 7 pages, 2 figures, accepted for publication in JCA
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