Publication date: Feb 2019
Abstract:
A recent study of the X-ray source XMMUJ134736.6+173403 has revealed a
strong quasi-periodic modulation in the X-ray flux. The observation of
two quasiperiodic oscillations (QPOs) that occur on a daily timescale
and exhibit a 3:1 frequency ratio strongly supports the evidence for the
presence of an active galactic nucleus black hole (AGN BH). Assuming an
orbital origin of QPOs, we calculated the upper and lower limit on AGN
BH mass M and found M ≈ 107 – 109 M☉.
When we compare this to mass estimates of other sources,
XMMUJ134736.6+173403 appears to be the most massive source with
commensurable QPO frequencies, and its mass represents the current
observational upper limit on AGN BH mass based on QPO observations. We
note that it will be crucial for the falsification of particular
resonance models of QPOs whether only a single QPO with a frequency that
completes the harmonic sequence 3 : 2 : 1 is found in this source, or if
a new different pair of QPOs with frequencies in the 3 : 2 ratio is
found. The former case would agree with the prediction of the 3 : 2
epicyclic resonance model and BH mass M ≈ (5a2 + 8a +
8)×107 M☉, where a is a dimensionless BH spin.
Authors:
Goluchová, K.; Török, G.; Šrámková, E.; Abramowicz, M. A.; Stuchlík, Z.; Horák, J.;