{"arxiv_id":"1001.0359","title":"Circular Orbits in Extremal Reissner Nordstrom Spacetimes","abstract":"Circular null geodesic orbits, in extremal Reissner-Nordstrom spacetimes, are examined with regard to their stability, and compared with similar orbits in the near-extremal situation. Extremization of the effective potential for null circular orbits shows the existence of a stable circular geodesic in the extremal spacetime, precisely {\\it on} the event horizon, which coincides with its null geodesic generator. Such an orbit also emerges as a global minimum of the effective potential for circular {\\it timelike} orbits. This type of geodesic is of course absent in the corresponding near-extremal spacetime, as we show here, testifying to differences between the extremal limit of a generic RN spacetime and the exactly extremal geometry.","primary_cat":"gr-qc","cross_cats":[],"submitted_at":"2010-01-03T11:08:01+00:00","latest_version":2,"source":"arxiv","source_label":"arXiv","source_url":null,"has_pdf":true,"has_source":false,"verdict":null,"confidence":null,"one_line_summary":null,"novelty_score":null,"correctness_risk":null,"formal_verification":null,"upvotes":0,"downvotes":0,"pith_score":0,"inbound_count":6,"_links":{"html":"https://pith.science/paper/1001.0359","verdict":"/api/v1/verdicts/1001.0359"}}