DENSITY PROFILES IN SEYFERT OUTFLOWS

Journal Article · Thu Oct 01 04:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/703/2/1346· OSTI ID:21371900

Behar, Ehud ^[1]

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1. Department of Physics, Technion, Haifa 32000 (Israel)

For the past decade, ionized outflows of a few 100 km s{sup -1} from nearby Seyfert galaxies have been studied in great detail using high-resolution X-ray absorption spectra. A recurring feature of these outflows is their broad ionization distribution including essentially ions (e.g., of Fe) from neutral to fully ionized. The absorption measure distribution (AMD) is defined as the distribution of column density with ionization parameter |dN {sub H}/d(log xi)|. AMDs of Seyfert outflows can span up to 5 orders of magnitude in xi. We present the AMD of five outflows and show that they are all rather flat, perhaps slightly rising toward high ionization. More quantitatively, a power-law fit for log AMD propor to(log xi) {sup a} yields slopes of 0 < a < 0.4. These slopes tightly constrain the density profiles of the wind, which until now could be addressed only by theory. If the wind is distributed on large scales, the measured slopes imply a generic density radial profile of n propor to r {sup -{alpha}} with 1 < {alpha} < 1.3. This scaling rules out a mass conserving radial flow of n propor to r {sup -2}, or a constant density absorber, but is consistent with a nonspherical MHD outflow model in which n propor to r {sup -1} along any given line of sight. On the other hand, if ionization variations are a result of local (deltar) density gradients, e.g., as in the turbulent interstellar medium (ISM), the AMD slopes imply density scaling of n propor to deltar {sup -{alpha}} with 0.7 < {alpha} < 1.0, which is quite different from the scaling of approximately n propor to deltar {sup 0.4} found in the Milky Way ISM and typical of incompressible turbulence.

• OSTI ID: 21371900
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 703; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
DENSITY
FLUID MECHANICS
GALAXIES
HYDRODYNAMICS
IONIZATION
MAGNETOHYDRODYNAMICS
MECHANICS
MILKY WAY
PHYSICAL PROPERTIES
SEYFERT GALAXIES
SORPTION
SPECTRA
TURBULENCE
X-RAY GALAXIES
X-RAY SPECTRA