MongoDB using UTCDateTime in $gte doesn't work - php

Question

I'm writing a query to search for users created at specific date e.g.
$date = '2018-05-02 15:46:41.000Z';
User::raw(function ($col) use($date) {
return $col->aggregate([
['$match' =>
'created_at' => ['$gte' => new \MongoDB\BSON\UTCDateTime(strtotime($date))]
]
]);
});
Given an sample data like
{
"_id" : ObjectId("5ae9dd61ef7a5754f159c656"),
"name" : "Effie Larkin",
"created_at" : ISODate("2018-05-02 15:46:41.000Z"),
}...
Expected result should be
{
"users" : [
"_id" : {"$oid": "5ae9dd61ef7a5754f159c656"},
"name" "Effie Larkin",
"created_at" : "2018-05-02 15:46:41"
]
}...
But I get an empty json array []. I think the problem is in UTCDateTime function but I don't how to pass dateTime to it. I want to pass a time interval like 1 week ago or yesterday etc... if anyone can help me will be much appreciated, thanks
Update, the example below fixed it
$date = '2018-05-02';
User::raw(function ($col) use($date) {
return $col->aggregate([
['$match' =>
'created_at' => ['$gte' => new \MongoDB\BSON\UTCDateTime(strtotime($date)*1000)]
]
]);
});