SIMBAD references

2012ApJ...760..135R - Astrophys. J., 760, 135 (2012/December-1)

A variable ultraluminous X-ray source in a globular cluster in NGC 4649.

ROBERTS T.P., FABBIANO G., LUO B., KIM D.-W., STRADER J., MIDDLETON M.J., BRODIE J.P., FRAGOS T., GALLAGHER J.S., KALOGERA V., KING A.R. and ZEZAS A.

Abstract (from CDS):

We report the discovery of a new ultraluminous X-ray source associated with a globular cluster in the elliptical galaxy NGC 4649. The X-ray source was initially detected with a luminosity below 5x1038 erg/s, but in subsequent observations 7 and 11 years later it had brightened substantially to 2-3x1039 erg/s. Over the course of six separate observations it displayed significant spectral variability, in both continuum slope and absorption column. Short-term variability in the X-ray flux was also present in at least one observation. The properties of this object appear consistent with a stellar-mass black hole accreting at super-Eddington rates (i.e., in the ultraluminous accretion state), although a highly super-Eddington neutron star cannot be excluded. The coincidence of an increase in absorption column with a possible enhancement in short-term variability in at least one observation is suggestive of a clumpy, radiatively driven wind crossing our line of sight to the object.

Abstract Copyright:

Journal keyword(s): globular clusters: general - X-rays: binaries - X-rays: galaxies

Simbad objects: 13

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2021.07.24-01:15:26

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