X-Ray Reverberation Mapping and Dramatic Variability of Seyfert 1 Galaxy 1H 1934-063
Abstract
A fraction of active galactic nuclei (AGN) exhibit dramatic variability, which is observed on timescales down to minutes in the X-ray band. We introduce the case study of 1H 1934-063 (z = 0.0102), a Narrow-line Seyfert 1 among the brightest and most variable AGN ever observed with XMM-Newton. This work includes spectral and temporal analyses of a concurrent XMM-Newton and NuSTAR 2015 observation lasting 130 kiloseconds, during which the X-ray source exhibited a steep (factor of ∼6) plummet and subsequent full recovery of the flux level, accompanied by deviation from a single log-normal flux distribution. We rule out Compton-thin obscuration as the cause for this dramatic variability observed even at NuSTAR energies. In order to constrain coronal geometry, dynamics, and emission/absorption processes, we compare a detailed spectral fitting with a Fourier-based timing analysis. Similar to other well-studied, highly variable Seyfert 1s, this AGN is X-ray bright and displays strong reflection features. We find a narrower broad iron line component compared to most Seyfert 1s, and constrain the black hole spin to be <0.1, one of the lowest yet discovered for such systems. Combined spectral and timing results are consistent with a dramatic change in the continuum on timescales as short as a few kiloseconds dictating the nature of this variability. We also discover a Fe-K time lag, measuring a delay of 20 s between relativistically blurred reflection off the inner accretion flow and the hard X-ray continuum emission.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2018
- DOI:
- 10.3847/1538-4357/aae306
- arXiv:
- arXiv:1802.06056
- Bibcode:
- 2018ApJ...867...67F
- Keywords:
-
- accretion;
- accretion disks;
- black hole physics;
- galaxies: active;
- galaxies: individual: 1H 1934-063;
- galaxies: Seyfert;
- relativistic processes;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 13 pages, 11 figures, Accepted to ApJ