Abstract
In\~Shafieloo2009, Shafieloo, Sanhi and Starobinsky firstly proposed
the possibility that the current cosmic acceleration (CA) is slowing down. This
is rather counterintuitive, because a slowing down CA cannot be accommodated in
almost all the mainstream cosmological models. In this work, by exploring the
evolutionary trajectories of dark energy equation of state \$w(z)\$ and
deceleration parameter \$q(z)\$, we present a comprehensive investigation on the
slowing down of CA from both the theoretical and the observational sides. For
the theoretical side, we study the impacts of different \$w(z)\$ by using six
parametrization models, and then discuss the effects of spatial curvature. For
the observational side, we investigate the effects of different type Ia
supernovae (SNe Ia), different baryon acoustic oscillation (BAO), and different
cosmic microwave background (CMB) data, respectively. We find that the
evolution of CA are insensitive to the specific form of \$w(z)\$; in contrast, a
non-flat Universe more favors a slowing down CA than a flat Universe. Moreover,
we find that SNLS3 SNe Ia datasets favor a slowing down CA at 1\$\sigma\$
confidence level, while JLA SNe Ia samples prefer an eternal CA; in contrast,
the effects of different BAO data are negligible. In addition, compared with
CMB distance prior data, full CMB data more favor a slowing down CA. Since the
evolutionary behavior of CA depends on both the theoretical models and the
observational data, the possibility of slowing down CA cannot be confirmed by
current observations.
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