INTERPRETATION OF THE 115 DAY PERIODIC MODULATION IN THE X-RAY FLUX OF NGC 5408 X-1

Journal Article · Mon Dec 20 04:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/725/2/2480· OSTI ID:21476637

Foster, D L; Charles, P A ^[1]; Holley-Bockelmann, K ^[2]

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1. South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 (South Africa)
2. 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, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 725; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
BLACK HOLES
COSMIC RADIO SOURCES
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
ELECTROMAGNETIC RADIATION
GALAXIES
IONIZING RADIATIONS
MASS
MODULATION
PERIODICITY
PRECESSION
QUASARS
RADIATIONS
VARIATIONS
X RADIATION