J/A+A/686/A99 HST COS spectrum of I Zwicky 1 (Juranova+, 2024)
The outflowing ionised gas of I Zw 1 observed by HST COS.
Juranova A., Costantini E., Kriss G.A., Mehdipour M., Brandt W.N.,
Di Gesu L., Fabian A.C., Gallo L., Giustini M., Rogantini D., Wilkins D.R.
<Astron. Astrophys. 686, A99 (2024)>
=2024A&A...686A..99J 2024A&A...686A..99J (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Galaxies, Seyfert ; Spectra, ultraviolet
Keywords: galaxies: individual: I Zw 1 - quasars: absorption lines -
galaxies: Seyfert - ultraviolet: galaxies
Abstract:
We present an analysis of the Hubble Space Telescope Cosmic Origins
Spectrograph spectrum of IZw1 aiming to probe the absorbing medium
associated with the active galactic nucleus (AGN).
We fitted the emission spectrum and performed spectral analysis of the
identified absorption features to derive the corresponding ionic
column densities and covering fractions of the associated outflows. We
employed photoionisation modelling to constrain the total column
density and the ionisation parameter of four detected kinematic
components. By investigating the implications of the results together
with the observed kinematic properties of both emission and absorption
features, we derived constraints on the structure and geometry of the
absorbing medium in the AGN environment.
We find and characterise absorption line systems from outflowing
ionised gas in four distinct kinematic components, located at -60,
-280, -1950, and -2900km/s with respect to the source rest frame.
While the two slower outflows are consistent with a full covering of
the underlying radiation source, the well-constrained doublet line
ratios of the faster two, higher column density, outflows suggest
partial covering, with a covering fraction of Cf∼0.4. The faster
outflows show also line-locking in the N V doublet, a signature of
acceleration via line absorption. This makes IZw1 possibly the closest
object that shows evidence for hosting line-driven winds. The observed
-1950km/s absorption is likely due to the same gas as an X-ray
warm absorber. Furthermore, the behaviour in UV and X-ray bands
implies that this outflow has a clumpy structure. We find that the
highly asymmetric broad emission lines in IZw1, indicative of a
collimated, outflowing broad line region, are covered by the absorbing
gas. Finally, the strongest UV--X-ray absorber may be connected to
some of the blueshifted line emission, indicative of a more spatially
extended structure of this ionised medium.
Description:
HST COS spectrum of I Zwicky 1 stacked from observations obtained
during eight orbits between 20 and 22 January 2015 (program 13811)
with gratings G130 M and G160M, covering the wavelength range of
1133-1760A (PI: E. Costantini). The stacked spectrum is binned by 4
pixels.
Objects:
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RA (2000) DE Designation(s)
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00 53 34.93 +12 41 35.9 I Zwicky 1 = UGC 00545
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
spectrum.dat 33 14244 HST COS spectrum of I Zwicky 1
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See also:
J/A+A/417/515 : I Zw 1 unusual emission line spectrum (Veron-Cetty+, 2004)
J/ApJ/876/102 : Reverberation mapping of the Seyfert Zw I 1 (Huang+, 2019)
Byte-by-byte Description of file: spectrum.dat
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Bytes Format Units Label Explanations
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1- 9 F9.4 0.1nm lambda Observed wavelength
12- 21 E10.4 0.01J/s/m2/nm Flux Calibrated flux
24- 33 E10.4 0.01J/s/m2/nm e_Flux Uncertainity on calibrated flux
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Acknowledgements:
Anna Juranova, a.juranova(at)sron.nl
(End) Anna Juranova [SRON/API UvA], Patricia Vannier [CDS] 25-Mar-2024