High‐Resolution X‐Ray and Ultraviolet Spectroscopy of the Complex Intrinsic Absorption in NGC 4051 withChandraand theHubble Space Telescope

2001/04/20 by Matthew J. Collinge, M. J. Collinge, W. N. Brandt +13 · 137 citations
Physics and Astronomy · #Absorption (acoustics) #Absorption spectroscopy #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Hubble space telescope #Optics #Physics #Space Telescope Imaging Spectrograph #Spectral line #Spectral resolution #astro-ph

paper · pdf · doi:10.1086/321635

published in The Astrophysical Journal 557(1), 2-17 (IOP Publishing) · 16 pages, 13 figures included, LaTeX emulateapj5.sty, accepted for publication in The Astrophysical Journal (this version is the same as the first version)

arxiv created 2001/04/20 · openalex publication_date 2001/08/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

We present the results from simultaneous observations of the narrow-line Seyfert 1 galaxy NGC 4051 with the Chandra High Energy Transmission Grating Spectrometer and the Hubble Space Telescope Space Telescope Imaging Spectrograph. The X-ray grating spectrum reveals absorption and emission lines from hydrogen-like and helium-like ions of O, Ne, Mg, and Si. We resolve two distinct X-ray absorption systems: a high-velocity blueshifted system at -2340 ± 130 km s -1 and a low-velocity blueshifted system at -600 ± 130 km s -1 . In the UV spectrum we detect strong absorption, mainly from C IV, N V, and Si IV, that is resolved into as many as nine different intrinsic absorption systems with velocities between -650 and 30 km s -1 . Although the low-velocity X-ray absorption is consistent in velocity with many of the UV absorption systems, the high-velocity X-ray absorption seems to have no UV counterpart. In addition to the absorption and emission lines, we also observe rapid X-ray variability and a state of low X-ray flux during the last ≈15 ks of the observation. NGC 4051 has a soft X-ray excess that we fit in both the high and low X-ray flux states. The high-resolution X-ray spectrum directly reveals that the soft excess is not composed of narrow emission lines and that it has significant spectral curvature. A power-law model fails to fit it, while a blackbody produces a nearly acceptable fit. We compare the observed spectral variability with the results of previous studies of NGC 4051.

Citations

• The Space Telescope Imaging Spectrograph Design
• Physical Processes in the Interstellar Medium
• Extragalactic nebulae.

Cited by

• The Compact, Conical, Accretion‐Disk Warm Absorber of the Seyfert 1 Galaxy NGC 4051 and Its Implications for IGM‐Galaxy Feedback Processes
• Determining Central Black Hole Masses in Distant Active Galaxies and Quasars. II. Improved Optical and UV Scaling Relationships
• The Connection between the Narrow‐Line Region and the UV Absorbers in Seyfert Galaxies
• X-Ray Spectral Variability of the Seyfert Galaxy NGC 4051 Observed with Suzaku
• Density diagnostics of ionized outflows in active galactic nuclei
• Extreme slim accretion disks and narrow line Seyfert 1 galaxies: The nature of the soft X-ray hump
• A JET MODEL FOR THE BROADBAND SPECTRUM OF THE SEYFERT 1 GALAXY NGC 4051
• High-resolution X-ray spectroscopy of the low and high states of the Seyfert 1 galaxy NGC 4051 with Chandra LETGS
• Contemporaneous Chandra HETG and Suzaku X-ray observations of NGC 4051
• SIGNIFICANT X-RAY LINE EMISSION IN THE 5-6 keV BAND OF NGC 4051