You are publishing photo using the Graph API, not the dialog.
In fact you cannot post a photo using a dialog, that's the correct way of doing which you are following.
Another thing, instead of-
"object": {
"url": "https://graph.facebook.com/*******/picture?width=720&height=720"
}
simply send the url
parameter. The object
jey is not required.
And you can always check the response/error in console.log(response)