Spatially resolved X-ray spectroscopy of the archetype type 2 active galactic nucleus NGC 1068 with Chandra

Abstract We investigate spatial distributions of iron Kα (Fe-Kα) lines in the cental 100 pc of the Seyfert 2 galaxy NGC 1068 observed with Chandra. The spatial distributions of Fe-Kα lines, neutral and highly ionized, around the center of the galactic nucleus are not isotropic, as consistently confirmed in both image and spectral analyses. The hydrogen number density of the gas clouds responsible for the neutral Fe-Kα line emission is estimated to be 102–103 cm−3 for the sampled regions near the galactic core. The photo-ionization model, where iron is assumed to be ionized by X-rays from the galactic nucleus, yields ionization parameters lower than 19 for these clouds. The range of this ionization parameter is two or three orders of magnitude lower than the theoretically expected value to produce the observed helium-like Fe-Kα line intensities. Therefore, the photo-ionization model is excluded from the explanation of the amount of highly ionized iron that is responsible for the observed Fe-Kα lines. Also, we find anti-correlation in the spatial distributions between the molecular cloud in the area observed with ALMA and that of the Fe-Kα lines, including that from neutral iron. We suggest that X-ray iron-line and radio molecular cloud observations are complementary to probe the distribution of matters in the central regions around the cores of active galactic nuclei.

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Exosat Observations of H2252−035: Pulse Phase and Orbital Phase Dependent Low Energy Absorption and Iron Line Emission

International Astronomical Union Colloquium ◽

10.1017/s0252921100104993 ◽

1987 ◽

Vol 93 ◽

pp. 281-292

Author(s):

W. Pietsch ◽

W. Voges ◽

E. Kendziorra ◽

M. Pakull

Keyword(s):

Energy Absorption ◽

Line Emission ◽

Low Energy ◽

Gas Absorption ◽

X Rays ◽

Medium Energy ◽

Iron Line ◽

X Ray ◽

Low Energies ◽

Optical Light Curve

AbstractThe 805 sec pulsing X-ray source H2252−035 has been observed for 7 h on September 14/15 and on September 17, 1983 in X-rays with the low energy telescope and the medium energy detectors of EXOSAT. While below 2 keV the semiamplitude of the 805 s pulses is ~ 100% in the 2.3–7.9 keV band it is only ~ 40%. X-ray dips that are more pronounced in low energies occur simultaneously with the orbital minimum of the optical light curve. The medium energy spectra during dips with respect to the non dip spectrum can be explained by just enhanced cold gas absorption of an additional absorbing column of 2 1022 cm−2. Model spectra for the 805 s minimum have to include a strong iron emission line at 6.55 keV with an equivalent width of 3 keV in addition to a reduced continuum intensity (radiating area) and enhanced low energy absorption.

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Iron Line Emission from NGC1068

Symposium - International Astronomical Union ◽

10.1017/s0074180900140707 ◽

1989 ◽

Vol 134 ◽

pp. 167-172

Author(s):

Katsuji Koyama

Keyword(s):

Energy Range ◽

Power Law ◽

Equivalent Width ◽

Line Emission ◽

X Rays ◽

Iron Line ◽

X Ray ◽

Central Engine ◽

Photon Index ◽

The Continuum

X-ray emission in the 2–10 keV energy range was observed with the Ginga satellite from the Seyfert 2 galaxy NGC1068. The continuum spectrum can be described by a power-law of photon index about 1.5. An intense iron line at 6.5 keV with an equivalent width of 1.3 keV was clearly noticed. The X-ray flux was about 6 × 10 −12 erg/sec/cm2 or 3 × 1041 erg/sec, assuming a distance of 22 Mpc. The observed spectrum is consistent with the scattering and reprocessing of X-rays by the gas surrounding the central engine. With this picture we estimate that the X-ray flux of the central engine is about 1043 - 1044 erg/sec, a typical value for a Seyfert 1 galaxy.

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Separating line emission from star formation, shocks, and AGN ionization in NGC 1068

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1611 ◽

2019 ◽

Vol 487 (3) ◽

pp. 4153-4168 ◽

Cited By ~ 4

Author(s):

Joshua J D’Agostino ◽

Lisa J Kewley ◽

Brent A Groves ◽

Anne M Medling ◽

Enrico Di Teodoro ◽

...

Keyword(s):

Star Formation ◽

Star Formation Rate ◽

Formation Rate ◽

Three Dimensional ◽

Line Emission ◽

X Ray ◽

Diagnostic Diagram ◽

The Galaxy ◽

Ngc 1068 ◽

Many Sources

ABSTRACT In the optical spectra of galaxies, the separation of line emission from gas ionized by star formation and an active galactic nucleus (AGN), or by star formation and shocks, are very well-understood problems. However, separating line emission between AGN and shocks has proven difficult. With the aid of a new three-dimensional diagnostic diagram, we show the simultaneous separation of line emission from star formation, shocks, and AGN in NGC 1068, and quantify the ratio of star formation, shocks, and AGN in each spaxel. The AGN, shock, and star formation luminosity distributions across the galaxy accurately align with X-ray, radio, and CO(3–2) observations, respectively. Comparisons with previous separation methods show that the shocked emission heavily mixes with the AGN emission. We also show that if the H α flux is to be used as a star formation rate indicator, separating line emission from as many sources as possible should be attempted to ensure accurate results.

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Measurement of X-ray iron line emission from Cygnus X-3 with the OSO 8 crystal spectrometer

The Astrophysical Journal ◽

10.1086/156608 ◽

1978 ◽

Vol 226 ◽

pp. 282 ◽

Cited By ~ 4

Author(s):

H. L. Kestenbaum ◽

W. H.-M. Ku ◽

K. S. Long ◽

E. H. Silver ◽

R. Novick

Keyword(s):

Line Emission ◽

Crystal Spectrometer ◽

Iron Line ◽

X Ray

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X-Ray Spectrum of Cassiopeia a: Evidence for Iron Line Emission

The Astrophysical Journal ◽

10.1086/181275 ◽

1973 ◽

Vol 184 ◽

pp. L1 ◽

Cited By ~ 16

Author(s):

P. J. Serlemitsos ◽

E. A. Boldt ◽

S. S. Holt ◽

R. Ramaty ◽

A. F. Brisken

Keyword(s):

Line Emission ◽

Iron Line ◽

X Ray ◽

Cassiopeia A

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A Morphological Classification of Clusters of Galaxies from Einstein Images

Symposium - International Astronomical Union ◽

10.1017/s0074180900027455 ◽

1982 ◽

Vol 97 ◽

pp. 97-106 ◽

Cited By ~ 2

Author(s):

C. Jones ◽

W. Forman

Keyword(s):

Line Emission ◽

Stellar Systems ◽

Single Individual ◽

Clusters Of Galaxies ◽

Morphological Classification ◽

Iron Line ◽

Emission Process ◽

X Ray ◽

Extended Sources

The earliest Uhuru observations showed that cluster X-ray sources were not associated with single individual galaxies but were extended sources (Gursky et al. 1971, Kellogg et al. 1972, and Forman et al. 1972). The detection of iron line emission from X-ray spectroscopic observations (Mitchell et al. 1976 and Serlemitsos et al. 1977) showed both that the dominant X-ray emission process was thermal bremsstrahlung and that the gas had been processed through stellar systems before being injected into the intracluster medium.

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