scholarly journals Compton-Thick AGN in the NuSTAR ERA VII. A joint NuSTAR, Chandra, and XMM-Newton Analysis of Two Nearby, Heavily Obscured Sources

2021 ◽  
Vol 922 (2) ◽  
pp. 159
Author(s):  
A. Traina ◽  
S. Marchesi ◽  
C. Vignali ◽  
N. Torres-Albà ◽  
M. Ajello ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Energy Range ◽  
Active Galactic Nuclei ◽  
Column Density ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Line Of Sight ◽  
Broad Energy Range ◽  
Larger Sample ◽  
Broad Energy

Abstract We present the joint Chandra, XMM-Newton, and NuSTAR analysis of two nearby Seyfert galaxies, NGC 3081 and ESO 565-G019. These are the only two having Chandra data in a larger sample of 10 low-redshift (z ≤ 0.05), candidates Compton-thick (CT) Active Galactic Nuclei selected in the 15–150 keV band with Swift-BAT that were still lacking NuSTAR data. Our spectral analysis, performed using physically motivated models, provides an estimate of both the line-of-sight (l.o.s.) and average (N H,S ) column densities of the two torii. NGC 3081 has a Compton-thin l.o.s. column density N H,z = [0.58–0.62] × 1024 cm−2, but the N H,S , beyond the CT threshold (N H,S = [1.41–1.78] × 1024 cm−2), suggests a “patchy” scenario for the distribution of the circumnuclear matter. ESO 565-G019 has both CT l.o.s. and N H,S column densities (N H,z > 2.31 × 1024 cm−2 and N H,S > 2.57 × 1024 cm−2, respectively). The use of physically motivated models, coupled with the broad energy range covered by the data (0.6–70 keV and 0.6–40 keV, for NGC 3081 and ESO 565-G019, respectively) allows us to constrain the covering factor of the obscuring material, which is C TOR = [0.63–0.82] for NGC 3081, and C TOR = [0.39–0.65] for ESO 565-G019.

scholarly journals X-ray spectral and eclipsing model of the clumpy obscurer in active galactic nuclei

2019 ◽  
Vol 629 ◽  
pp. A16 ◽  
Author(s):  
Johannes Buchner ◽  
Murray Brightman ◽  
Kirpal Nandra ◽  
Robert Nikutta ◽  
Franz E. Bauer
Keyword(s):  
Active Galactic Nuclei ◽  
Column Density ◽  
Galactic Nuclei ◽  
Line Of Sight ◽  
Broad Line ◽  
X Ray ◽  
Line Region ◽  
Self Consistent ◽  
Multi Wavelength ◽  
Table Model

We present a unification model for a clumpy obscurer in active galactic nuclei (AGN) and investigate the properties of the resulting X-ray spectrum. Our model is constructed to reproduce the column density distribution of the AGN population and cloud eclipse events in terms of their angular sizes and frequency. We developed and released a generalised Monte Carlo X-ray radiative transfer code, XARS, to compute X-ray spectra of obscurer models. The geometry results in strong Compton scattering, causing soft photons to escape also along Compton-thick sight lines. This makes our model spectra very similar to our TORUS previous model. However, only if we introduce an additional Compton-thick reflector near the corona, we achieve good fits to NuSTAR spectra. This additional component in our model can be interpreted as part of the dust-free broad-line region, an inner wall or rim, or a warped disk. It cannot be attributed to a simple disk because the reflector must simultaneously block the line of sight to the corona and reflect its radiation. We release our model as an Xspec table model and present corresponding CLUMPY infrared spectra, paving the way for self-consistent multi-wavelength analyses.

scholarly journals Are Compton-thin AGNs Globally Compton Thin?

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.

scholarly journals Multiphase quasar-driven outflows in PG 1114+445

2019 ◽  
Vol 627 ◽  
pp. A121 ◽  
Author(s):  
Roberto Serafinelli ◽  
Francesco Tombesi ◽  
Fausto Vagnetti ◽  
Enrico Piconcelli ◽  
Massimo Gaspari ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Column Density ◽  
Large Scale ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
X Rays ◽  
Substantial Evidence ◽  
Surrounding Environment ◽  
High Ionization ◽  
Ionization Velocity

Substantial evidence in the last few decades suggests that outflows from supermassive black holes (SMBH) may play a significant role in the evolution of galaxies. These outflows, powered by active galactic nuclei (AGN), are thought to be the fundamental mechanism by which the SMBH transfers a significant fraction of its accretion energy to the surrounding environment. Large-scale outflows known as warm absorbers (WA) and fast disk winds known as ultra-fast outflows (UFO) are commonly found in the spectra of many Seyfert galaxies and quasars, and a correlation has been suggested between them. Recent detections of low ionization and low column density outflows, but with a high velocity comparable to UFOs, challenge such initial possible correlations. Observations of UFOs in AGN indicate that their energetics may be enough to have an impact on the interstellar medium (ISM). However, observational evidence of the interaction between the inner high-ionization outflow and the ISM is still missing. We present here the spectral analysis of 12 XMM-Newton/EPIC archival observations of the quasar PG 1114+445, aimed at studying the complex outflowing nature of its absorbers. Our analysis revealed the presence of three absorbing structures. We find a WA with velocity v ∼ 530 km s−1, ionization log ξ/erg cm s−1 ∼ 0.35, and column density log NH/cm−2 ∼ 22, and a UFO with vout ∼ 0.145c, log ξ/erg cm s−1 ∼ 4, and log NH/cm−2 ∼ 23. We also find an additional absorber in the soft X-rays (E <  2 keV) with velocity comparable to that of the UFO (vout ∼ 0.120c), but ionization (log ξ/erg cm s−1 ∼ 0.5) and column density (log NH/cm−2 ∼ 21.5) comparable with those of the WA. The ionization, velocity, and variability of the three absorbers indicate an origin in a multiphase and multiscale outflow, consistent with entrainment of the clumpy ISM by an inner UFO moving at ∼15% the speed of light, producing an entrained ultra-fast outflow (E-UFO).

scholarly journals A deep X-ray view of the bare AGN Ark 120

2018 ◽  
Vol 609 ◽  
pp. A42 ◽  
Author(s):  
D. Porquet ◽  
J. N. Reeves ◽  
G. Matt ◽  
A. Marinucci ◽  
E. Nardini ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Line Of Sight ◽  
Constant Density ◽  
High Flux ◽  
X Rays ◽  
X Ray ◽  
Intrinsic Absorption ◽  
The Continuum

Context. The physical characteristics of the material closest to supermassive black holes (SMBHs) are primarily studied through X-ray observations. However, the origins of the main X-ray components such as the soft X-ray excess, the Fe Kα line complex, and the hard X-ray excess are still hotly debated. This is particularly problematic for active galactic nuclei (AGN) showing a significant intrinsic absorption, either warm or neutral, which can severely distort the observed continuum. Therefore, AGN with no (or very weak) intrinsic absorption along the line of sight, so-called “bare AGN”, are the best targets to directly probe matter very close to the SMBH. Aims. We perform an X-ray spectral analysis of the brightest and cleanest bare AGN known so far, Ark 120, in order to determine the process(es) at work in the vicinity of the SMBH. Methods. We present spectral analyses of data from an extensive campaign observing Ark 120 in X-rays with XMM-Newton (4 × 120 ks, 2014 March 18–24), and NuSTAR (65.5 ks, 2014 March 22). Results. During this very deep X-ray campaign, the source was caught in a high-flux state similar to the earlier 2003 XMM-Newton observation, and about twice as bright as the lower-flux observation in 2013. The spectral analysis confirms the “softer when brighter” behavior of Ark 120. The four XMM-Newton/pn spectra are characterized by the presence of a prominent soft X-ray excess and a significant Fe Kα complex. The continuum is very similar above about 3 keV, while significant variability is present for the soft X-ray excess. We find that relativistic reflection from a constant-density, flat accretion disk cannot simultaneously produce the soft excess, broad Fe Kα complex, and hard X-ray excess. Instead, Comptonization reproduces the broadband (0.3–79 keV) continuum well, together with a contribution from a mildly relativistic disk reflection spectrum. Conclusions. During this 2014 observational campaign, the soft X-ray spectrum of Ark 120 below ~0.5 keV was found to be dominated by Comptonization of seed photons from the disk by a warm (kTe ~ 0.5 keV), optically-thick corona (τ ~ 9). Above this energy, the X-ray spectrum becomes dominated by Comptonization from electrons in a hot optically thin corona, while the broad Fe Kα line and the mild Compton hump result from reflection off the disk at several tens of gravitational radii.

scholarly journals Polarimetric Properties of Blazars Caught by the WEBT

Galaxies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 42
Author(s):  
Claudia M. Raiteri ◽  
Massimo Villata
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Plasma Jets ◽  
Line Of Sight ◽  
Optical Behaviour ◽  
Relativistic Jets ◽  
Comprehensive Picture ◽  
Multi Wavelength ◽  
Extreme Variability ◽  
Continuous Range

Active galactic nuclei come in many varieties. A minority of them are radio-loud, and exhibit two opposite prominent plasma jets extending from the proximity of the supermassive black hole up to megaparsec distances. When one of the relativistic jets is oriented closely to the line of sight, its emission is Doppler beamed and these objects show extreme variability properties at all wavelengths. These are called “blazars”. The unpredictable blazar variability, occurring on a continuous range of time-scales, from minutes to years, is most effectively investigated in a multi-wavelength context. Ground-based and space observations together contribute to give us a comprehensive picture of the blazar emission properties from the radio to the γ-ray band. Moreover, in recent years, a lot of effort has been devoted to the observation and analysis of the blazar polarimetric radio and optical behaviour, showing strong variability of both the polarisation degree and angle. The Whole Earth Blazar Telescope (WEBT) Collaboration, involving many tens of astronomers all around the globe, has been monitoring several blazars since 1997. The results of the corresponding data analysis have contributed to the understanding of the blazar phenomenon, particularly stressing the viability of a geometrical interpretation of the blazar variability. We review here the most significant polarimetric results achieved in the WEBT studies.

scholarly journals Understanding the origin of radio outflows in Seyfert galaxies using radio polarimetry

2019 ◽  
Vol 15 (S356) ◽  
pp. 247-251
Author(s):  
Biny Sebastian ◽  
Preeti Kharb ◽  
Christopher P. O’ Dea ◽  
Jack F. Gallimore ◽  
Stefi A. Baum ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Radio Emission ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Seyfert Galaxy ◽  
Seyfert Galaxies ◽  
Starburst Galaxies ◽  
Galactic Magnetic Fields ◽  
5 Ghz

AbstractThe role of starburst winds versus active galactic nuclei (AGN) jets/winds in the formation of the kiloparsec scale radio emission seen in Seyferts is not yet well understood. In order to be able to disentangle the role of various components, we have observed a sample of Seyfert galaxies exhibiting kpc-scale radio emission suggesting outflows, along with a comparison sample of starburst galaxies, with the EVLA B-array in polarimetric mode at 1.4 GHz and 5 GHz. The Seyfert galaxy NGC 2639, shows highly polarized secondary radio lobes, not observed before, which are aligned perpendicular to the known pair of radio lobes. The additional pair of lobes represent an older epoch of emission. A multi-epoch multi-frequency study of the starburst-Seyfert composite galaxy NGC 3079, reveals that the jet together with the starburst superwind and the galactic magnetic fields might be responsible for the well-known 8-shaped radio lobes observed in this galaxy. We find that many of the Seyfert galaxies in our sample show bubble-shaped lobes, which are absent in the starburst galaxies that do not host an AGN.

scholarly journals Subtraction of Bright Point Sources from Synthesis Images of the Epoch of Reionization

2011 ◽  
Vol 28 (1) ◽  
pp. 46-57 ◽  
Author(s):  
B. Pindor ◽  
J. S. B. Wyithe ◽  
D. A. Mitchell ◽  
S. M. Ord ◽  
R. B. Wayth ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Dynamic Range ◽  
Low Frequency ◽  
Neutral Hydrogen ◽  
Galactic Nuclei ◽  
Point Sources ◽  
Field Of View ◽  
Bright Point ◽  
Line Of Sight ◽  
Diffuse Background

AbstractBright point sources associated with extragalactic active galactic nuclei and radio galaxies are an important foreground for low-frequency radio experiments aimed at detecting the redshifted 21-cm emission from neutral hydrogen during the epoch of reionization. The frequency dependence of the synthesized beam implies that the sidelobes of these sources will move across the field of view as a function of observing frequency, hence frustrating line-of-sight foreground subtraction techniques. We describe a method for subtracting these point sources from dirty maps produced by an instrument such as the MWA. This technique combines matched filters with an iterative centroiding scheme to locate and characterize point sources in the presence of a diffuse background. Simulations show that this technique can improve the dynamic range of epoch-of-reionization maps by 2—3 orders of magnitude.

scholarly journals Chemical abundances in Seyfert galaxies – V. The discovery of shocked emission outside the AGN ionization axis

2020 ◽  
Vol 501 (1) ◽  
pp. L54-L59
Author(s):  
R A Riffel ◽  
O L Dors ◽  
M Armah ◽  
T Storchi-Bergmann ◽  
A Feltre ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Active Galactic Nuclei ◽  
Direct Evidence ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Chemical Abundances ◽  
Temperature Distributions ◽  
Field Unit ◽  
Dusty Torus ◽  
Integral Field

ABSTRACT We present maps for the electron temperature in the inner kpc of three luminous Seyfert galaxies: Mrk 79, Mrk 348, and Mrk 607 obtained from Gemini Multi-Object Spectrograph-integral field unit observations at spatial resolutions of ∼110–280 pc. We study the distributions of electron temperature in active galaxies and find temperatures varying in the range from ∼8000 to $\gtrsim 30\, 000\,$K. Shocks due to gas outflows play an important role in the observed temperature distributions of Mrk 79 and Mrk 348, while standard photoionization models reproduce the derived temperature values for Mrk 607. In Mrk 79 and Mrk 348, we find direct evidence for shock ionization with overall orientation orthogonal to the ionization axis, where shocks can be easily observed as the active galactic nuclei radiation field is shielded by the nuclear dusty torus. This also indicates that even when the ionization cones are narrow, the shocks can be much wider angle.

scholarly journals Spectral Variability in Seyfert Galaxies

1987 ◽  
Vol 121 ◽  
pp. 161-167
Author(s):  
B.M. Peterson
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Broad Line ◽  
Spectral Variability ◽  
Broad Line Region ◽  
Broad Emission ◽  
Line Region ◽  
Order Of Magnitude ◽  
Optical Continuum

Recent observations of spectral variability in active galactic nuclei have established the connection between the broad emission-line and optical continuum flux changes. The inferred size of the broad-line region is at least an order of magnitude smaller than conventional estimates based on photoionization models, which leads to new conclusions about the nature of the broad-line region.

scholarly journals Active Galactic Nuclei in the Extreme Ultraviolet

1996 ◽  
Vol 152 ◽  
pp. 27-36
Author(s):  
Arieh Königl
Keyword(s):  
Active Galactic Nuclei ◽  
Extreme Ultraviolet ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Potential Usefulness ◽  
Spectral Features ◽  
Bl Lacertae Objects ◽  
Spectroscopic Measurements ◽  
Bl Lacertae ◽  
Unique Information

EUV observations could provide valuable and unique information about the nature of active galactic nuclei. I discuss their potential usefulness and review some of the main results obtained so far with the ROSAT WFC and the EUVE instruments. About three dozen sources, mostly Seyfert galaxies and BL Lacertae objects, have already been identified, and spectroscopic measurements of several of them have yielded a number of surprises. However, more observations are clearly needed to confirm some of the reported spectral features and to validate their interpretation.

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