Active particles in heterogeneous media display new physics

摘要: We present a detailed study of the large-scale collective properties self-propelled particles (SPPs) moving in two-dimensional heterogeneous space. The impact spatial heterogeneities on ordered, collectively phase is investigated. show that for strong enough heterogeneity, well-documented high-density, high-ordered propagating bands emerge homogeneous space disappear. Moreover, ordered does not exhibit long-range order, as occurs systems, but rather quasi-long range order: i.e. SPP system becomes disordered thermodynamical limit. For finite size we find there an optimal noise value maximizes order. Interestingly, two limits, high values well vanishing noise. This remarkable finding strongly suggests existence critical points, instead only one, associated to motion transition. Density fluctuations are consistent with these observations, being higher and anomalously at noise, decreasing crossing over normal low values. Collective investigated static dynamic environments, by changing symmetry velocity alignment mechanism SPPs.