  Statistical studies of exoplanets have shown that giant planets are more
commonly hosted by metal-rich dwarf stars than low-metallicity ones, while such
a correlation is not evident for lower-mass planets. The search for giant
planets around metal-poor stars and the estimate of their occurrence $f_p$ is
an important element in providing support to models of planet formation. We
present results from the HARPS-N search for giant planets orbiting metal-poor
($-1.0\leq[Fe/H]\leq-0.5$ dex) stars in the northern hemisphere complementing a
previous HARPS survey on southern stars in order to update the estimate of
$f_p$. High-precision HARPS-N observations of 42 metal-poor stars are used to
search for planetary signals to be fitted using differential evolution MCMC
single-Keplerian models. We then join our detections to the results of the
previous HARPS survey on 88 metal-poor stars to provide a preliminar estimate
of the two-hemisphere $f_p$. We report the detection of two new giant planets
around HD 220197 and HD 233832. The first companion has
M$\sin{i}=0.20_{-0.04}^{+0.07}$ M$_{\rm Jup}$ and orbital period of
$1728_{-80}^{+162}$ days, and for the second companion we find two solutions of
equal statistical weight having periods $2058_{-40}^{+47}$ and
$4047_{-117}^{+91}$ days and minimum masses of $1.78_{-0.06}^{+0.08}$ and
$2.72_{-0.23}^{+0.23}$ M$_{\rm Jup}$, respectively. Joining our two detections
with the three from the southern survey we obtain a preliminary and
conservative estimate of global frequency of $f_p=3.84_{-1.06}^{+2.45}\%$ for
giant planets around metal-poor stars. The two new giant planets orbit dwarf
stars at the metal-rich end of the HARPS-N metal-poor sample, corroborating
previous results suggesting that giant planet frequency still is a rising
function of host star [Fe/H]. We also note that all detections in the overall
sample are giant long-period planets.
