Test for Echo: X-Ray Reflection Variability in the Seyfert-2 Active Galactic Nucleus NGC 4388
Abstract
We report on a study of the narrow Fe Kα line and reflection spectrum in the well-known Seyfert-2 active galactic nucleus (AGN), NGC 4388. X-ray spectra summed from two extensive NICER monitoring campaigns, separated by years, show strong evidence of variation in the direct continuum and reflected emission, but only small variations in the obscuring gas. Fits to the spectra from individual NICER observations find a strong, positive correlation between the power-law photon index, Γ, and direct flux that is commonly observed in unobscured AGN. A search for a reverberation lag between the direct and reflected spectra—dominated by the narrow Fe Kα emission line—measures a timescale of
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 2024
- DOI:
- 10.3847/1538-4357/ad2fa3
- arXiv:
- arXiv:2403.00926
- Bibcode:
- 2024ApJ...966...57G
- Keywords:
-
- Black holes;
- X-ray active galactic nuclei;
- Active galactic nuclei;
- 162;
- 2035;
- 16;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- Accepted for publication in ApJ