New Evidence for Black Hole Event Horizons from Chandra
نویسندگان
چکیده
Previously we claimed that Black Hole X-ray Novae (BHXN) in quiescence are much less luminous than equivalent Neutron Star X-ray Novae (NSXN). This claim was based on the quiescent detection of a single short period BHXN (A0620–00, Porb=7.8 hrs) and two longer period BHXN (GRO J1655–40, Porb=62.9 hrs; V404 Cyg, Porb=155.3 hrs), along with sensitive upper limits. We announce the detection of two more short period BHXN (GRO J0422+32, Porb=5.1 hrs; GS 2000+25, Porb=8.3 hrs), an upper limit for a third which is improved by two orders of magnitude (4U 1543–47, Porb=27.0 hrs) and a new, much lower quiescent measurement of GRO J1655– 40. Taken together, these new Chandra measurements confirm that the quiescent X-ray luminosities of BHXN are significantly lower than those of NSXN. We argue that this provides strong evidence for the existence of event
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