  Collider, space, and Earth based experiments are now able to probe several
extensions of the Standard Model of particle physics which provide viable dark
matter candidates. Direct and indirect dark matter searches rely on inputs of
astrophysical nature, such as the local dark matter density or the shape of the
dark matter profile in the target in object. The determination of these
quantities is highly affected by astrophysical uncertainties. The latter,
especially those for our own Galaxy, are ill-known, and often not fully
accounted for when analyzing the phenomenology of particle physics models. In
this paper we present a systematic, quantitative estimate of how astrophysical
uncertainties on Galactic quantities (such as the local galactocentric
distance, circular velocity, or the morphology of the stellar disk and bulge)
propagate to the determination of the phenomenology of particle physics models,
thus eventually affecting the determination of new physics parameters. We
present results in the context of two specific extensions of the Standard Model
(the Singlet Scalar and the Inert Doublet) that we adopt as case studies for
their simplicity in illustrating the magnitude and impact of such uncertainties
on the parameter space of the particle physics model itself. Our findings point
toward very relevant effects of current Galactic uncertainties on the
determination of particle physics parameters, and urge a systematic estimate of
such uncertainties in more complex scenarios, in order to achieve constraints
on the determination of new physics that realistically include all known
uncertainties.
