TY - JOUR
T1 - Fading of the X-ray flux from the black hole in the NGC 4472 globular cluster RZ 2109
AU - Maccarone, Thomas J.
AU - Kundu, Arunav
AU - Zepf, Stephen E.
AU - Rhode, Katherine L.
PY - 2010/11
Y1 - 2010/11
N2 - We present the results of new X-ray observations of XMMU 122939.7+075333, the black hole (BH) in the globular cluster RZ 2109 in the Virgo cluster galaxy NGC 4472. A combination of non-detections and marginal detections in several recent Swift and Chandra observations show that the source has varied by at least a factor of 20 in the past 6 yr, and that the variations seem not just to be 'flickering'. This variation could be explained with changes in the absorption column intrinsic to the source no larger than those which were previously seen near the peak of the 1989 outburst of the Galactic BH X-ray binary V404 Cyg. The large amplitude variations are also a natural expectation from a hierarchical triple system with Kozai cycles - the mechanism recently proposed to produce BH-white dwarf (WD) binaries in globular clusters. On the other hand, variation by such a large factor on time-scales of years, rather than centuries, is very difficult to reconcile with the scenario in which the X-ray emission from XMMU 122939.7+075333 is due to fallback of material from a tidally destroyed or detonated WD.
AB - We present the results of new X-ray observations of XMMU 122939.7+075333, the black hole (BH) in the globular cluster RZ 2109 in the Virgo cluster galaxy NGC 4472. A combination of non-detections and marginal detections in several recent Swift and Chandra observations show that the source has varied by at least a factor of 20 in the past 6 yr, and that the variations seem not just to be 'flickering'. This variation could be explained with changes in the absorption column intrinsic to the source no larger than those which were previously seen near the peak of the 1989 outburst of the Galactic BH X-ray binary V404 Cyg. The large amplitude variations are also a natural expectation from a hierarchical triple system with Kozai cycles - the mechanism recently proposed to produce BH-white dwarf (WD) binaries in globular clusters. On the other hand, variation by such a large factor on time-scales of years, rather than centuries, is very difficult to reconcile with the scenario in which the X-ray emission from XMMU 122939.7+075333 is due to fallback of material from a tidally destroyed or detonated WD.
KW - Galaxies: star clusters: individual: NGC 4472
KW - Globular clusters: general
KW - Stars: binaries
KW - X-rays: binaries
UR - http://www.scopus.com/inward/record.url?scp=78751555591&partnerID=8YFLogxK
U2 - 10.1111/j.1745-3933.2010.00953.x
DO - 10.1111/j.1745-3933.2010.00953.x
M3 - Letter
AN - SCOPUS:78751555591
SN - 1745-3933
VL - 409
SP - L84-L88
JO - Monthly Notices of the Royal Astronomical Society: Letters
JF - Monthly Notices of the Royal Astronomical Society: Letters
IS - 1
ER -