Time-evolving Diagnostic of the Ionized Absorbers in NGC 4051. I. High-resolution Time-averaged Spectroscopy
Year: 2025
Type: article
Abstract: We present a high-resolution X-ray spectroscopic study of the narrow-line Seyfert 1 galaxy NGC 4051 using two XMM-Newton high-resolution Reflection Grating Spectrometer observations. The spectra reveal three distinct layers of photoionized gas flowing outward from the central black hole: a low-ionization phase (LIP), a higher-ionization phase (HIP), and a high-velocity and high-ionization phase (HVIP). Each absorber leaves characteristic imprints on the soft X-ray spectrum. While the LIP and HVIP are fully consistent with being in ionization equilibrium with the central radiation field over the course of the ∼250 ks spanned by the two observations, the HIP shows a significant change in ionization (3.8 σ ), suggesting nonequilibrium. By modeling the two spectra with our time-dependent photoionization code ( TEPID ), we constrain the density of the HIP gas to log n H = 7 . 7 − 0.9 + 0.2 and estimate its distance to be about R = 0.4 5 − 0.09 + 0.80 lt-day from the black hole, corresponding to R = 400 0 − 800 + 7000 gravitational radii. In contrast, the narrow soft X-ray emission lines remain constant, consistent with an origin in the more extended narrow-line region. Our results show the value of combining high-resolution and time-resolved spectroscopy to probe the structure, physical conditions, and variability of active galactic nucleus outflows.
Source: The Astrophysical Journal
Authors: Roberto Serafinelli, Fabrizio Nicastro, Alfredo Luminari, Yair Krongold, Francesco Camilloni, Elias Kammoun, Riccardo Middei, Enrico Piconcelli, Luigi Piro
Institutions: Astronomical Observatory of Rome, National Institute for Astrophysics, Universidad Diego Portales, Institute for Space Astrophysics and Planetology, Universidad Nacional Autónoma de México, California Institute of Technology, Agenzia Spaziale Italiana, Center for Astrophysics Harvard & Smithsonian
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Funders: National Aeronautics and Space Administration, California Institute of Technology, Agencia Nacional de Investigación y Desarrollo, Goddard Space Flight Center, Smithsonian Astrophysical Observatory, Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México, Astrophysics Science Division, Astrophysics Division
OpenAlex ID: W7108239196