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Revisiting The Spectral and Timing Properties of NGC 4151
A Zoghbi1, J M Miller1, E Cackett2
1Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA.
The Astrophysical Journal
|September 9, 2020
Summary
New X-ray observations of NGC 4151 reveal absorption effects, not relativistic reflection, cause energy-dependent lags. The narrow Fe Kα line originates in the inner broad line region (BLR).
Area of Science:
- High-energy astrophysics
- Active galactic nuclei (AGN) research
- X-ray astronomy
Background:
- NGC 4151 is a prominent Seyfert 1 galaxy, notable for its bright X-ray emission.
- Previous studies suggested relativistic reverberation in the Fe K band indicated phenomena near the black hole.
- Short time delays in X-ray emissions were previously attributed to relativistic effects.
Purpose of the Study:
- To investigate short time delays in NGC 4151 using extensive XMM-Newton data from a 2015 campaign.
- To re-evaluate the nature of spectral components and time lags in NGC 4151.
- To understand the origin and variability of the narrow Fe Kα line.
Main Methods:
- Analysis of high-quality XMM-Newton X-ray data spanning hours to decades.
- Spectral analysis incorporating neutral and ionized absorption.
- Investigation of energy-dependent time lags and variability of the Fe Kα line.
Main Results:
- Neutral and ionized absorption significantly influence the X-ray spectral shape.
- No evidence for relativistic reflection was found, contrary to earlier interpretations.
- Energy-dependent lags were detected but attributed to absorption, not relativistic effects; the narrow Fe Kα line varies and is delayed relative to the continuum, originating in the inner broad line region (BLR).
Conclusions:
- The observed energy-dependent lags in NGC 4151 are likely caused by absorption processes.
- The narrow Fe Kα line's variability and delay suggest an origin within the inner broad line region (BLR).
- The measured delay of the Fe Kα line is shorter than that of the Hβ line, implying a different geometry for the inner BLR compared to the optical BLR.
Keywords:
NGC 4151
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