X-ray Reverberation close to the black hole in RE J1034+396

Abstract

In previous work, we discussed the detection of reverberation delays in the NLS1 1H0707-495. The delays originate close to the black hole. Here, we show that RE J1034+396 shows very similar lag properties. At low frequencies (< 1 \times 10-4 Hz), the time lag between energy bands increases with energy separation, similar to that commonly seen in Galactic black holes and other AGN. At higher frequencies (~ 3.5 \times 10-4 Hz), the soft (< 1 keV) and hard (> 3 keV) bands lag behind the intermediate band (1-3 keV). The simplest interpretation is that the intermediate band is dominated by the direct power-law continuum, while the soft and hard bands are dominated by the relativistically-smeared reflected emission. The low frequency delays are present in both available observations. The high frequency lags are only seen in one observation. In the observation where high frequency reverberation delays are observed, the spectrum contains a power-law component and there is a QPO in the light curve. In the other observation, no power-law component is required and no QPO is seen. The lags originate a few gravitational radii from the black hole, and the QPO is associated with the power-law emitting corona.