J/A+A/615/A72 NGC 7469 X-ray spectra (Mehdipour+, 2018)
Multi-wavelength campaign on NGC 7469.
III. Spectral energy distribution and the AGN wind photoionisation modelling,
plus detection of diffuse X-rays from the starburst with Chandra HETGS.
Mehdipour M., Kaastra J.S., Costantini E., Behar E., Kriss G.A., Bianchi S.,
Branduardi-Raymont G., Cappi M., Ebrero J., Di Gesu L., Kaspi S., Mao J.,
De Marco B., Middei R., Peretz U., Petrucci P.-O., Ponti G., Ursini F.
<Astron. Astrophys. 615, A72 (2018)>
=2018A&A...615A..72M 2018A&A...615A..72M (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Spectroscopy
Keywords: X-rays: galaxies - galaxies: active - galaxies: Seyfert -
galaxies: individual: NGC 7469 - techniques: spectroscopic
Abstract:
We investigate the physical structure of the active galactic nucleus
(AGN) wind in the Seyfert-1 galaxy NGC 7469 through high-resolution
X-ray spectroscopy with Chandra HETGS and photoionisation modelling.
Contemporaneous data from Chandra, HST, and Swift are used to model
the optical-UV-X-ray continuum and determine the spectral energy
distribution (SED) at two epochs, 13yr apart. For our investigation we
use new observations taken in December 2015-January 2016, and
historical ones taken in December 2002. We study the impact of a
change in the SED shape, seen between the two epochs, on the
photoionisation of the wind. The HETGS spectroscopy shows that the AGN
wind in NGC 7469 consists of four ionisation components, with their
outflow velocities ranging from -400 to -1800km/s. From our modelling
we find that the change in the ionising continuum shape between the
two epochs results in some variation in the ionisation state of the
wind components. However, for the main ions detected in X-rays, the
sum of their column densities over all components remains in practice
unchanged. For two of the four components, which are found to be
thermally unstable in both epochs, we obtain 2<r<31pc and 12<r<29pc
using the cooling and recombination timescales. For the other two
thermally stable components, we obtain r<31pc and r<80pc from the
recombination timescale. The results of our photoionisation modelling
and thermal stability analysis suggest that the absorber components in
NGC 7469 are consistent with being a thermally driven wind from the
AGN torus. Finally, from analysis of the zeroth-order ACIS/HETG data,
we discover that the X-ray emission in the range 0.2-1keV is spatially
extended over 1.5-12". This diffuse soft X-ray emission is explained
by coronal emission from the nuclear starburst ring in NGC 7469. The
star formation rate inferred from this diffuse soft X-ray emission is
consistent with those found by far-infrared studies of NGC 7469.
Description:
All Chandra observations of NGC 7469 have been taken with HETGS
(Canizares et al., 2005PASP..117.1144C 2005PASP..117.1144C). The most recent HETGS
observation, hereafter referred to as the 2015 observation, spans over
the end of December 2015 and the beginning of January 2016. These new
data are presented for the first time in this paper.
Tables of the reduced Chandra HETGS spectra (HEG and MEG) and the
best-fit model to the spectra (Figs. 3 and 7 in the paper).
Objects:
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RA (2000) DE Designation(s)
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23 03 15.67 +08 52 25.3 NGC 7469 = Mrk 1514
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
heg2002.dat 148 98 2002 HEG spectrum of the Fe Ka line (Fig. 3)
heg2016.dat 148 98 2016 HEG spectrum of the Fe Ka line (Fig. 3)
megstack.dat 103 1418 Stacked MEG spectrum (Fig. 7)
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See also:
J/AZh/71/200 : Spectral Investigation of NGC 7469 (Doroshenko+, 1994)
J/PAZh/21/652 : Optical variability in NGC 7469 (Lyuty+, 1995)
J/ApJ/795/149 : Reverberation mapping of Seyfert 1 NGC 7469 (Peterson+, 2014)
Byte-by-byte Description of file: heg2002.dat heg2016.dat
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Bytes Format Units Label Explanations
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1- 14 E14.7 keV E Observed energy (bin central energy)
16- 29 E14.7 keV E_E Observed energy positive error
31- 44 E14.7 keV e_E Observed energy negative error
46- 59 E14.7 10ph/m2/s/nm F Data photon flux (ph/m2/s/Å)
61- 74 E14.7 10ph/m2/s/nm E_F Data photon flux positive error
76- 89 E14.7 10ph/m2/s/nm e_F Data photon flux negative error
91-104 E14.7 10ph/m2/s/nm Mod Model photon flux (ph/m2/s/Å)
105-119 E15.7 --- Res Fit residual = (Data-Model)/Model
121-134 E14.7 --- E_Res Fit residual positive error
136-148 E13.7 --- e_Res Fit residual negative error
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Byte-by-byte Description of file: megstack.dat
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Bytes Format Units Label Explanations
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1- 14 E14.7 0.1nm lambda Observed wavelength (bin centre)
16- 29 E14.7 0.1nm e_lambda Observed wavelength positive error
31- 44 E14.7 0.1nm E_lambda Observed wavelength negative error
46- 59 E14.7 10ph/m2/s/nm F Data photon flux (ph/m2/s/Å)
61- 74 E14.7 10ph/m2/s/nm e_F Data photon flux positive error
76- 89 E14.7 10ph/m2/s/nm E_F Data photon flux negative error
91-103 E13.7 10ph/m2/s/nm Mod Model photon flux (ph/m2/s/Å
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Acknowledgements:
Missagh Mehdipour, M.Mehdipour(at)sron.nl
(End) Missagh Mehdipour [SRON], Patricia Vannier [CDS] 07-Aug-2018