A high-density relativistic reflection origin for the soft and hard X-ray excess emission from Mrk 1044

作者：Mallick L^*; Alston W N^*; Parker M L^*; Fabian A C; Pinto C; Dewangan G C; Markowitz A; Gandhi P; Kembhavi A K; Misra R

来源：Monthly Notices of the Royal Astronomical Society, 2018, 479(1): 615-634.

DOI：10.1093/mnras/sty1487

• accretion, accretion discs
• black hole physics
• relativistic processes
• galaxies: active
• galaxies: Seyfert

We present the first results from a detailed spectral-timing analysis of a long (similar to 130 ks) XMM-Newton observation and quasi-simultaneous NuSTAR and Swift observations of the highly accreting narrow-line Seyfert 1 galaxy Mrk 1044. The broadband (0.3-50 keV) spectrum reveals the presence of a strong soft X-ray excess emission below similar to 1.5 keV, iron K-alpha emission complex at similar to 6-7 keV and a 'Compton hump' at similar to 15-30 keV. We find that the relativistic reflection from a high-density accretion disc with a broken power-law emissivity profile can simultaneously explain the soft X-ray excess, highly ionized broad iron line and the Compton hump. At low frequencies ([2 - 6] x 10(-5) Hz), the power-law continuum dominated 1.5-5 keV band lags behind the reflection dominated 0.3-1 keV band, which is explained with a combination of propagation fluctuation and Comptonization processes, while at higher frequencies ([1 - 2] x 10(-4) Hz), we detect a soft lag which is interpreted as a signature of X-ray reverberation from the accretion disc. The fractional root-mean-squared variability of the source decreases with energy and is well described by two variable components: a less variable relativistic disc reflection and a more variable direct coronal emission. Our combined spectral-timing analyses suggest that the observed broadband X-ray variability of Mrk 1044 is mainly driven by variations in the location or geometry of the optically thin, hot corona.

• 出版日期2018-9