High-frequency iron K reverberation lags , where the red wing of the line responds before the line centroid , are a robust signature of relativistic reflection off the inner accretion disc .
In this letter , we report the discovery of the Fe K lag in PG 1244+026 from \sim 120 ks of data ( 1 orbit of the XMM-Newton telescope ) .
The amplitude of the lag with respect to the continuum is 1000 s at a frequency of \sim 10 ^ { -4 } Hz .
We also find a possible frequency-dependence of the line : as we probe higher frequencies ( i.e .
shorter timescales from a smaller emitting region ) the Fe K lag peaks at the red wing of the line , while at lower frequencies ( from a larger emitting region ) we see the dominant reflection lag from the rest frame line centroid .
The mean energy spectrum shows a strong soft excess , though interestingly , there is no indication of a soft lag .
Given that this source has radio emission and it has little reported correlated variability between the soft excess and the hard band , we explore one possible explanation in which the soft excess in this source is dominated by the steep power-law like emission from a jet , and that a corona ( or base of the jet ) irradiates the inner accretion disc , creating the blurred reflection features evident in the spectrum and the lag .
General Relativistic ray-tracing models fit the Fe K lag well , with the best-fit giving a compact X-ray source at a height of 5 r _ { \mathrm { g } } and a black hole mass of 1.3 \times 10 ^ { 7 } M _ { \sun } .