GET _search
{
  "_source": ["title","release_date"], 
  "query": {
    "function_score": {
      "query": {
        "match_all": {}
      },
      "functions": [
        {
          "gauss": {
            "release_date": {
              "origin": "now",
              "scale": "900d",
              "decay": 0.5
            }
          }
        }
      ]
    }
  }
}