Abstract:

From cosmological observations we know that dark matter must display clustering properties similar to cold dark matter(CDM) at least on the largest scales. However, the particle nature of DM is still not known. But at smaller scales the situation remains unclear from astrophysical observations which does not agree well with CDM predictions. Non-detection of CDM in direct search experiments and  small scale astrophysical anomalies might be giving us strong hints to look for other particle physics candidates of dark matter arising from different physics. I will discuss one such scenario where dark matter arises much later in the universe though light sterile neutrinos present in radiation dominated era.