Can unix timestamp be used as field in date histogram?

Hi,

I am building a log analysis tool and want to create the timeline series graph of the number of log entries logged.

I wish to use the date histogram feature for it. A query like:
"facets" : {
"histo1" : {
"date_histogram" : {
"field" : "field_name",
"interval" : "day"
}
}
}
would work just fine for me. I dont have any field in the "date" format, so I was wondering if I can use the unix timestamp field I have indexed in my elasticsearch for the same purpose. Its a date in different format.

I tried a couple of things myself, didnt work. Can you please suggest?

Thanks and Regards,
Komal.