Galaxy and structure formation with hot dark matter and cosmic strings

Galaxy and structure formation in a neutrino-dominated universe with cosmic strings is investigated. Strings survive neutrino-free streaming to seed galaxies and clusters. The effective maximum Jeans mass is about 1.5×{}10¹⁴{n}₅₀^{{{-}}4}M_, lower than in the adiabatic scenario. Hence cluster formation is only marginally different from that in the cold-dark-matter and strings model, but galaxy masses are lower. The mass spectrum of galaxies is flatter than with cold dark matter, and the density profile about an individual loop is less steep, in better agreement with observations.