As an aunt can I file for temporary custody of my niece if her mother has abandon her?

Where did she abandon her? And how long ago?

For a while abandonment meant left without any supervision. Meaning that leaving a child with a trusted adult was not abandonment. But it looks like they may have changed the law again to any of these, but probably depending on state law.
Leaving a child with another person without provision for the child's support and without meaningful communication with the child for a period of three months;
Making only minimal efforts to support and communicate with a child
Failing for a period of at least six months to maintain regular visitation with a child;
Failed to participate in a suitable plan or program designed to reunite the parent or guardian with a child;
Leaving an infant on a doorstep, in trash cans and dumpsters, and on the side of the road
Being absent from the home for a period that created a substantial risk of serious harm to a child left in the home
Failing to respond to notice of child protective proceedings; or
Being unwilling to provide care, support, or supervision for the child

You need to define what happened. What do you mean by abandoned? Where is the child now? How old is the child?