Probing the nuclear and circumnuclear properties of NGC 6300 using X-ray observations

ABSTRACT We present the results obtained from a detailed X-ray timing and spectral analysis of the Seyfert 2 galaxy NGC 6300 by using observations from the Suzaku observatory, theChandra X-ray Observatory and the Nuclear Spectroscopic Telescope Array(NuSTAR) mission between 2007 and 2016. We calculate the variance and the rms fractional variability of the source in different energy bands and we find variabilities in various energy bands. Spectral properties of the source are studied by using various phenomenological and physical models. The properties of the Compton clouds, reflection, Fe Kα line emission and soft X-ray excess are studied in detail. Several physical parameters of the source are extracted and investigated to establish the presence/absence of any correlation between them. We also investigate the nature of the circumnuclear ‘torus’ and we find that the torus is not uniform, but clumpy. The observed changes in the line-of-sight column density can be explained in terms of transiting clouds. The iron line-emitting region is found to be different in the different epochs of observations. We also observe that the torus and the nucleus independently evolve over the years.

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Are Compton-thin AGNs Globally Compton Thin?

The Astrophysical Journal ◽

10.3847/1538-4357/ac1ff6 ◽

2021 ◽

Vol 922 (1) ◽

pp. 85

Author(s):

P. Tzanavaris ◽

T. Yaqoob ◽

S. LaMassa ◽

A. Ptak ◽

M. Yukita

Keyword(s):

Emission Line ◽

Active Galactic Nuclei ◽

Column Density ◽

Line Emission ◽

Galactic Nuclei ◽

Line Of Sight ◽

X Ray ◽

Hydrogen Column Density ◽

Model Configuration

Abstract We select eight nearby active galactic nuclei (AGNs) which, based on previous work, appear to be Compton-thin in the line of sight. We model with mytorus their broadband X-ray spectra from 20 individual observations with Suzaku, accounting self-consistently for Fe Kα line emission, as well as direct and scattered continuum from matter with finite column density and solar Fe abundance. Our model configuration allows us to measure the global, out of the line of sight, equivalent hydrogen column density separately from that in the line of sight. For 5 out of 20 observations (in 3 AGNs) we find that the global column density is in fact ≳1.5 × 1024 cm−2, consistent with the distant scattering matter being Compton-thick. For a fourth AGN, two out of five observations are also consistent with being Compton-thick, although with large errors. Some of these AGNs have been reported to host relativistically broadened Fe Kα emission. Based on our modeling, the Fe Kα emission line is not resolved in all but two Suzaku observations, and the data can be fitted well with models that only include a narrow Fe Kα emission line.

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A broad-band X-ray spectral study of the Seyfert 1 galaxy ESO 141–G055 with XMM–Newton and NuSTAR

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2259 ◽

2020 ◽

Vol 497 (4) ◽

pp. 4213-4221

Author(s):

Ritesh Ghosh ◽

Sibasish Laha

Keyword(s):

Black Hole ◽

Spectral Study ◽

Column Density ◽

Broad Band ◽

Accretion Disc ◽

Physical Models ◽

X Ray ◽

Reflection Model ◽

Ionization Parameter

ABSTRACT We have extensively studied the broad--band X-ray spectra of the source ESO 141–G055 using all available XMM–Newton and NuSTAR observations. We detect a prominent soft excess below $2\rm \, \, {\rm keV}$, a narrow Fe line, and a Compton hump ($\gt 10\rm \, \, {\rm keV}$). The origin of the soft excess is still debated. We used two models to describe the soft excess: the blurred reflection from the ionized accretion disc and the intrinsic thermal Comptonization model. We find that both of these models explain the soft excess equally well. We confirm that we do not detect any broad Fe line in the X-ray spectra of this source, although both the physical models prefer a maximally spinning black hole scenario (a > 0.96). This may mean that either the broad Fe line is absent or blurred beyond detection. The Eddington rate of the source is estimated to be $\lambda _{\rm \, Edd}\sim 0.31$. In the reflection model, the Compton hump has a contribution from both ionized and neutral reflection components. The neutral reflector which simultaneously describes the narrow Fe K α and the Compton hump has a column density of $N_{\rm H} \ge 7\times 10^{24} \, \rm cm^{-2}$. In addition, we detect a partially covering ionized absorption with ionization parameter $\log \xi /\rm \, erg\, cm\, s^{-1}$ = $0.1^{+0.1}_{-0.1}$ and column density $N_{\rm H} =20.6^{+1.0}_{-1.0}\times 10^{22} \, \rm cm^{-2}$ with a covering factor of $0.21^{+0.01}_{-0.01}$.

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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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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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Tracing Small-Scale Fluctuations in the Soft X-ray Background

International Astronomical Union Colloquium ◽

10.1017/s0252921100071189 ◽

1997 ◽

Vol 166 ◽

pp. 321-324

Author(s):

R. Warwick ◽

I. Hutchinson ◽

R. Willingale ◽

K. Kuntz ◽

S. Snowden

Keyword(s):

Column Density ◽

Galactic Halo ◽

Inverse Correlation ◽

Line Of Sight ◽

Small Scale ◽

X Ray ◽

Hydrogen Column Density ◽

X Ray Background ◽

Counting Statistics ◽

Made In

AbstractAn overlapping set of ROSAT PSPC observations made in a region of very low Galactic foreground column density, has been used to investigate variations in the soft X-ray background on angular scales of 15′ – 5°. In the ¼ keV band there is a clear inverse correlation of the count-rate with the line-of-sight hydrogen column density. However, after correcting for this absorption effect, strong residual fluctuations remain in the data, with an amplitude which is significantly larger than that due to the counting statistics or the confusion of unresolved discrete sources. In contrast a similar analysis for the ¾ and 1.5 keV ROSAT bands shows no evidence for an excess signal. The most likely origin of the ¼ keV fluctuations would seem to be in a patchy distribution of ~ 106 K gas in the Galactic halo.

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