An Active Galactic Nucleus Sample with High X‐Ray–to–Optical Flux Ratio from RASS. II. Optical Emission Line Properties of Seyfert 1–Type Active Galactic Nuclei

2003 ◽  
Vol 590 (1) ◽  
pp. 73-85 ◽  
Author(s):  
D. W. Xu ◽  
Stefanie Komossa ◽  
J. Y. Wei ◽  
Y. Qian ◽  
X. Z. Zheng
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Active Galactic Nucleus ◽  
Flux Ratio ◽  
Galactic Nuclei ◽  
Optical Emission ◽  
X Ray ◽  
Optical Flux

scholarly journals XMM–Newton study of X-ray sources in the field of Willman 1 dwarf spheroidal galaxy★

2020 ◽  
Vol 499 (3) ◽  
pp. 3111-3129
Author(s):  
Sara Saeedi ◽  
Manami Sasaki
Keyword(s):  
Active Galactic Nuclei ◽  
Cross Correlation ◽  
Flux Ratio ◽  
Galactic Nuclei ◽  
Symbiotic Star ◽  
X Ray ◽  
Dwarf Spheroidal Galaxies ◽  
Infrared Wavelengths ◽  
Optical Flux ◽  
M Dwarf

ABSTRACT We present the results of the analysis of three XMM–Newton observations of the Willman 1 dwarf spheroidal galaxy (Wil 1). X-ray sources are classified on the basis of spectral analysis, hardness ratios, X-ray-to-optical flux ratio, X-ray variability, and cross-correlation with available catalogues in optical and infrared wavelengths. We catalogued 97 sources in the field of Wil 1. Our classification shows the presence of a β-type symbiotic star in Wil 1. We classified one M dwarf foreground star in the field of Wil 1. Moreover, 54 sources are classified as background active galactic nuclei and galaxies. Our study shows that the luminosity of the X-ray sources of Wil 1 does not exceed ∼1034 erg s−1 in the energy range of 0.2–12.0 keV, which is similar to observed luminosities of sources in nearby dwarf spheroidal galaxies.

scholarly journals Structure and Emission Line Spectrum of an X-ray Heated Accretion Disk in AGN

1994 ◽  
Vol 159 ◽  
pp. 484-484
Author(s):  
Yuan-Kuen Ko ◽  
Timothy R. Kallman
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Line Emission ◽  
Galactic Nuclei ◽  
X Ray ◽  
Disk Size ◽  
Emission Line Spectrum ◽  
Self Gravity ◽  
A Site

We investigate the structure of an X-ray heated accretion disk in active galactic nuclei. It is found that X-ray heating can prevent the disk to be disrupted by its self-gravity under sufficient X-ray heating. The disk size can be two orders of magnitute larger than that limited by self-gravity of the disk without X-ray heating. An accretion disk corona will be formed by X-ray heating and can be a site for line emission. We present such emission line spectra which range from optical to hard X-ray energies and compare with the observational data.

scholarly journals X-Ray Properties of Galactic Nuclei

1980 ◽  
Vol 5 ◽  
pp. 623-630
Author(s):  
Daniel W. Weedman
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Seyfert Galaxy ◽  
Seyfert Galaxies ◽  
Strong Emission ◽  
X Ray ◽  
Ngc 4151 ◽  
Survey Results ◽  
Emission Line Galaxies

Preparing this review was my just punishment for stating only two years ago - in another review (Weedman 1977) - that Seyfert galaxies are not strong X-ray sources. I said that because, as recently as three years ago, NGC 4151 was the only Seyfert galaxy known as an X-ray source. Now we have 36 Seyfert 1 galaxies, along with 12 other galaxies with strong emission-line nuclei, that are X-ray sources. And this is all without even having HEAO-2 data at our disposal yet. The study of active galactic nuclei with X-ray astronomy is progressing so rapidly that a reviewer feels almost hopeless. The best I can do is summarize what is known as of the summer of 1979 and give a simple overview of how X-ray and other properties relate.Some excellent reviews of the X-ray properties of Seyfert and other emission-line galaxies already exist. I especially recommend that by Andrew Wilson (1979). He provides very complete references as of a year ago, but X-ray astronomy is progressing so rapidly that he then had only somewhat more than half the active nuclei now in Tables 1 and 2. It was the group working with the Ariel V SSI that made the initial comprehensive X-ray studies of Seyfert galaxies (Ward et al. 1977, Elvis et al. 1978). The UHURU results for Seyfert galaxies followed soon after and are summarized by Tananbaum et al. (1978); the HEAO-A-2 survey results are now in press (Marshall et al. 1979) I have tried to incorporate these and other recent results in Tables 1 and 2.

scholarly journals The Galactic center: not an active galactic nucleus

2013 ◽  
Vol 9 (S303) ◽  
pp. 54-58
Author(s):  
Deokkeun An ◽  
Solange V. Ramírez ◽  
Kris Sellgren
Keyword(s):  
Interstellar Medium ◽  
Emission Line ◽  
Active Galactic Nuclei ◽  
Active Galactic Nucleus ◽  
Galactic Center ◽  
Galactic Nuclei ◽  
Extensive Area ◽  
Star Forming ◽  
Nearby Galaxies

AbstractWe present 10 μm – 35μm Spitzer spectra of the interstellar medium in the central molecular zone (CMZ), the central 210 pc × 60 pc of the Galactic center (GC). We present maps of the CMZ in ionic and H2 emission, covering a more extensive area than earlier spectroscopic surveys in this region. We compare diagnostic line ratios measured in the Spitzer Infrared Nearby Galaxies Survey to our data. Previous work shows that forbidden line ratios can distinguish star-forming galaxies from low-ionization nuclear emission-line regions (LINERs) and active galactic nuclei (AGNs). Our GC line ratios agree with star-forming galaxies and not with LINERs or AGNs.

scholarly journals Exploring the active galactic nuclei population with extreme X-ray-to-optical flux ratios (fx/fo > 50)

2015 ◽  
Vol 447 (4) ◽  
pp. 3227-3242 ◽  
Author(s):  
R. Della Ceca ◽  
F. J. Carrera ◽  
A. Caccianiga ◽  
P. Severgnini ◽  
L. Ballo ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
X Ray ◽  
Optical Flux

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 The mass-metallicity relation of high-z type-2 active galactic nuclei

2018 ◽  
Vol 616 ◽  
pp. L4 ◽  
Author(s):  
K. Matsuoka ◽  
T. Nagao ◽  
A. Marconi ◽  
R. Maiolino ◽  
F. Mannucci ◽  
...  
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Rest Frame ◽  
Galactic Nuclei ◽  
Radio Galaxies ◽  
Stellar Mass ◽  
Line Flux ◽  
X Ray ◽  
Stellar Masses

The mass-metallicity relation (MZR) of type-2 active galactic nuclei (AGNs) at 1.2 < z < 4.0 is investigated by using high-z radio galaxies (HzRGs) and X-ray selected radio-quiet AGNs. We combine new rest-frame ultraviolet (UV) spectra of two radio-quiet type-2 AGNs obtained with FOCAS on the Subaru Telescope with existing rest-frame UV emission lines, i.e., C IVλ1549, He IIλ1640, and C IIIλ1909, of a sample of 16 HzRGs and 6 additional X-ray selected type-2 AGNs, whose host stellar masses have been estimated in literature. We divided our sample in three stellar mass bins and calculated averaged emission-line flux ratios of C IVλ1549/He IIλ1640 and C IIIλ1909/C IVλ1549. Comparing observed emission-line flux ratios with photoionization model predictions, we estimated narrow line region (NLR) metallicities for each mass bin. We found that there is a positive correlation between NLR metallicities and stellar masses of type-2 AGNs at z ~ 3. This is the first indication that AGN metallicities are related to their hosts, i.e., stellar mass. Since NLR metallicities and stellar masses follow a similar relation as the MZR in star-forming galaxies at similar redshifts, our results indicate that NLR metallicities are related to those of the host galaxies. This study highlights the importance of considering lower-mass X-ray selected AGNs in addition to radio galaxies to explore the metallicity properties of NLRs at high redshift.

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