This is not New Age stuff, so put away your crystals, Kirlian imaging gear and sexuo-mystical expectations. It's not that kind of aura.
This aura is a medical phenomenon that a small number of people afflicted with epilepsy have experienced as a prelude to a seizure or certain kinds of headaches. The technical term for an aura that precedes a seizure or migraine is 'ictal aura'. This particular type of ictal aura, however, seems to have an upside: it produces a strong orgasm-like sensation. Unfortunately for male sufferers, this aura happens mostly to women. The discovering doctors report that one female patient refused medication because she didn't want the aura to go away.
The orgasmic aura was first recognized by Dr. Jozsef Janszky in one of his female patients in Hungary who reported having an 'orgasm-like euphoric erotic feeling' just before her seizures. By screening existing records, researchers found 22 other patients who had also reported this orgasmic aura experience since 1945. There are no professional medical reports prior to 1945, but a number of similar episodes can be found described in literary works.
Examination of the medical records revealed that the seizures always originated in the non-dominant side of the brain, which is usually the right side, and possibly in or near the amygdala, which suggests that particular area of the brain is the site for at least an important part of what females experience as orgasm. A perhaps even more interesting implication is that male and female orgasms are fundamentally different and are associated with different parts of the brain. Also, that the women did not report having the full experience of an orgasm during the aura suggests that orgasm is a compound or composite experience that comprises multiple contributing effects and sensations. Such a model would help explain how orgasms may vary in degree or even kind, particularly in women.
Origin in brain