2016A&A...589A..76G


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.04CET17:15:12

2016A&A...589A..76G - Astronomy and Astrophysics, volume 589A, 76-76 (2016/5-1)

The thermal instability of the warm absorber in NGC 3783.

GOOSMANN R.W., HOLCZER T., MOUCHET M., DUMONT A.-M., BEHAR E., GODET O., GONCALVES A.C. and KASPI S.

Abstract (from CDS):

Context. The X-ray absorption spectra of active galactic nuclei frequently show evidence of winds with velocities in the order of 103 km/s extending up to 104 km/s in the case of ultra-fast outflows. At moderate velocities, these winds are often spectroscopically explained by assuming a number of absorbing clouds along the line of sight. In some cases it was shown that the absorbing clouds are in pressure equilibrium with each other.
Aims. We assume a photo-ionized medium with a uniform total (gas+radiation) pressure. The irradiation causes the wind to be radiation pressure compressed (RPC). We attempt to reproduce the observed spectral continuum shape, ionic column densities, and X-ray absorption measure distribution (AMD) of the extensively observed warm absorber in the Seyfert galaxy NGC 3783.
Methods. We compare the observational characteristics derived from the 900 ks Chandra observation to radiative transfer computations in pressure equilibrium using the radiative transfer codeTITAN. We explore different values of the ionization parameter ξ of the incident flux and adjust the hydrogen-equivalent column density, NH0, of the warm absorber to match the observed soft X-ray continuum. From the resulting models we derive the column densities for a broad range of ionic species of iron and neon and a theoretical AMD that we compare to the observations.
Results. We find an extension of the degeneracy between ξ and NH0 for the constant pressure models previously discussed for NGC 3783. Including the ionic column densities of iron and neon in the comparison between observations and data we conclude that a range of ionization parameters between 4000 and 8000erg*cm/s is preferred. For the first time, we present theoretical AMDs for a constant pressure wind in NGC 3783 that correctly reproduces the observed level and is in approximate agreement with the observational appearance of an instability region.
Conclusions. Using a variety of observational indicators, we confirm that the X-ray outflow of NGC 3783 can be described as an RPC medium in pressure equilibrium. The observed AMD agrees with a uniformly hot or a uniformly cold thermal state. The measured ionic column densities suggest that the wind tends to the uniformly cold thermal state. The occurrence of thermal instability in the warm absorber model may depend on the computational method and the spatial scale on which the radiative transfer is solved.

Abstract Copyright: © ESO, 2016

Journal keyword(s): radiative transfer - galaxies: active - galaxies: individual: NGC 3783 - galaxies: Seyfert - X-rays: galaxies

CDS comments: IRAS 13449+2438 is a misprint for IRAS F13349+2438.

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 M 77 GiP 02 42 40.771 -00 00 47.84 9.70 9.61 8.87 10.1 9.9 ~ 4179 2
2 NGC 3516 Sy1 11 06 47.4596406816 +72 34 07.189563769   13.12 12.40     ~ 1437 0
3 NGC 3783 Sy1 11 39 01.7095761008 -37 44 19.008597647   12.46 13.43 11.33 12.1 ~ 1500 0
4 ESO 383-35 Sy1 13 35 53.7686909139 -34 17 44.139127597   13.89 13.61 8.9   ~ 1400 0
5 2RE J1337+244 Sy1 13 37 18.7198121987 +24 23 03.320690345     15.0     ~ 365 0
6 NGC 5548 Sy1 14 17 59.5401093128 +25 08 12.600227883   14.35 13.73     ~ 2445 0
7 Mrk 509 Sy1 20 44 09.7504131334 -10 43 24.724854084   13.35 13.12 10.7   ~ 1149 0
8 NGC 7469 Sy1 23 03 15.674 +08 52 25.28 12.60 13.00 12.34     ~ 1919 3

    Equat.    Gal    SGal    Ecl

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2021.03.04-17:15:12

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