INTERPRETATION OF THE 115 DAY PERIODIC MODULATION IN THE X-RAY FLUX OF NGC 5408 X-1
- South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 (South Africa)
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN (United States)
We comment on the recent observation of a 115 day modulation in the X-ray flux of the ultraluminous X-ray source (ULX) NGC 5408 X-1, and in particular, the interpretation of this modulation as the orbital period. We suggest that this modulation may instead be due to a precessing jet, and is thus superorbital in nature. Comparing the properties of this ULX with those of the prototypical micro-quasar SS 433, we argue that NGC 5408 X-1 is very similar to SS 433: a hyper-accreting stellar-mass black hole in a shorter-period binary. If the analogy holds, the 115 day modulation is best explained by the still poorly understood physics of inner-disk/jet precession and a longer observing baseline would be able to reveal an intrinsic phase jitter that is associated with such a precession.
- OSTI ID:
- 21476637
- Journal Information:
- Astrophysical Journal, Vol. 725, Issue 2; Other Information: DOI: 10.1088/0004-637X/725/2/2480; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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