Details

Autor(en) / Beteiligte

• Krongold, Y
• Elvis, M
• Andrade-Velazquez, M
• Nicastro, F
• Mathur, S
• Reeves, J. N
• Brickhouse, N. S
• Binette, L
• Jimenez-Bailon, E
• Grupe, D
• Liu, Y
• McHardy, I. M
• Minezaki, T
• Yoshii, Y
• Wilkes, B

Titel

Suzaku Monitoring of the Seyfert 1 Galaxy NGC 5548: Warm Absorber Location and Its Implication for Cosmic Feedback

Ist Teil von

• The Astrophysical journal, 2010-02, Vol.710 (1), p.360-371

Ort / Verlag

Bristol: IOP Publishing

Erscheinungsjahr

2010

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• We present a 2 month Suzaku X-ray monitoring of the Seyfert 1 galaxy NGC 5548. The campaign consists of seven observations (with exposure time of {approx}30 ks each), separated by {approx}1 week. This paper focus on the X-ray Imaging Spectrometer data of NGC 5548. We analyze the response in the opacity of the gas that forms the well-known ionized absorber in this source for ionizing flux variations. Despite variations by a factor of {approx}4 in the impinging continuum, the soft X-ray spectra of the source show little spectral variations, suggesting no response from the ionized absorber. A detailed time modeling of the spectra confirms the lack of opacity variations for an absorbing component with high ionization (U{sub X} {approx} -0.85), and high outflow velocity (v{sub out} {approx} 1040 km s{sup -1}), as the ionization parameter was found to be consistent with a constant value during the whole campaign. Instead, the models suggest that the ionization parameter of a low ionization (U{sub X} {approx} -2.8), low velocity (v{sub out} {approx} 590 km s{sup -1}) absorbing component might be changing linearly with the ionizing flux, as expected for gas in photoionization equilibrium. However, given the lack of spectral variations among observations, we consider the variations in this component as tentative. Using the lack of variations, we set an upper limit of n{sub e} < 2.0 x 10{sup 7} cm{sup -3} for the electron density of the gas forming the high ionization, high velocity component. This implies a large distance from the continuum source (R>0.033 pc; R>5000R{sub S} ). If the variations in the low ionization, low velocity component are real, they imply n{sub e} >9.8 x 10{sup 4} cm{sup -3} and R < 3 pc. We discuss our results in terms of two different scenarios: a large-scale outflow originating in the inner parts of the accretion disk, or a thermally driven wind originating much farther out. Given the large distance of the wind, the implied mass outflow rate is also large; the mass outflow is dominated by the high ionization component). The associated total kinetic energy deployed by the wind in the host galaxy (>1.2 x 10{sup 56} erg) can be enough to disrupt the interstellar medium, possibly quenching or regulating large-scale star formation. However, the total mass and energy ejected by the wind may still be lower than the one required for cosmic feedback, even when extrapolated to quasar luminosities. Such feedback would require that we are observing the wind before it is fully accelerated.