scholarly journals Seyfert Galaxies and the Hard X-Ray Background: ArtificialChandraObservations of [FORMULA][F]z=0.3[/F][/FORMULA] Active Galaxies

2006 ◽  
Vol 131 (1) ◽  
pp. 133-142 ◽  
Author(s):  
K. C. Peterson ◽  
S. C. Gallagher ◽  
A. E. Hornschemeier ◽  
M. P. Muno ◽  
E. C. Bullard
Keyword(s):  
Seyfert Galaxies ◽  
Active Galaxies ◽  
X Ray ◽  
X Ray Background

Extragalactic X-ray sources and the diffuse X-ray background

1979 ◽  
Vol 366 (1726) ◽  
pp. 391-402 ◽  
Keyword(s):  
Spatial Distribution ◽  
Euclidean Space ◽  
Active Galaxies ◽  
Clusters Of Galaxies ◽  
Optical Identification ◽  
X Ray ◽  
Luminosity Functions ◽  
Sky Survey ◽  
Order Of Magnitude ◽  
X Ray Background

Results from the Ariel 5 sky survey instrument relating to the properties and the spatial distribution of extragalactic X-ray sources are discussed. The lg N -lg S relation for sources in the 2A catalogue is consistent with a uniform distribution of sources in Euclidean space. In addition, measure­ments of fluctuations in the X-ray background suggest that the Euclidean form of the source counts can be extrapolated to flux levels at least an order of magnitude fainter than the 2A catalogue limit. Information is also available from the optical identification of 2A sources which, through redshift measurements, enables the X-ray luminosity functions of the two main classes of source, namely clusters of galaxies and active galaxies, to be determined. The luminosity functions can be used to calculate the contribution of clusters of galaxies and active galaxies to the diffuse X-ray background in the 2-10 keV range. It is found that cosmological evolution of one or both populations is required to account for the diffuse X-ray background entirely in terms of the integrated emission from these sources.

scholarly journals 9.18. Galactic winds in active galaxies

1998 ◽  
Vol 184 ◽  
pp. 417-418 ◽  
Author(s):  
S. Veilleux ◽  
J. Bland-Hawthorn ◽  
G. Cecil ◽  
P. Shopbell
Keyword(s):  
Absorption Line ◽  
Galaxy Formation ◽  
Large Scale ◽  
Large Scale Structure ◽  
Active Galaxies ◽  
Large Scale Circulation ◽  
X Ray ◽  
Hubble Sequence ◽  
Galactic Winds ◽  
X Ray Background

The effects of large-scale galactic winds in active galaxies may be far-reaching. It has been suggested that the Hubble sequence can be understood in terms of a galaxy's greater ability to sustain winds with increasing bulge-to-disk ratio. The large-scale circulation of gas associated with these galactic winds might help explain the mass-metallicity relation between galaxies and the metallicity-radius relation within galaxies. Galactic winds probably contribute non-negligibly to the cosmic X-ray background and may be involved in the quasar absorption-line phenomenon. The cosmological implications of the wind phenomenon have been widely explored in the context of proto-galaxies and quasars. The extremely energetic galactic winds that were likely associated with galaxy formation almost certainly played a key role in heating and ionizing the intergalactic medium at high redshifts and may have created the seeds for the large-scale structure we see today.

Optical Identification of the ROSAT All-Sky Survey Sources in Two 2° × 2° Fields

1997 ◽  
Vol 159 ◽  
pp. 427-428
Author(s):  
Y. Zhao ◽  
J. Zhong ◽  
J. Wei ◽  
J. Hu ◽  
Q. Li
Keyword(s):  
Ccd Camera ◽  
Seyfert Galaxies ◽  
Astronomical Observatory ◽  
Active Galaxies ◽  
Clusters Of Galaxies ◽  
Late Type ◽  
Optical Identification ◽  
X Ray ◽  
Sky Survey

AbstractWe used the CCD camera and spectrograph of the 2.16-m telescope of Beijing Astronomical Observatory to identify the ROSAT All-Sky survey sources in two 2° Ü 2° fields. Of a total of 16 X-ray sources, we identified 13 of them as follows: two QSOs, two Seyfert galaxies, two active galaxies, two clusters of galaxies, and five late-type stars. Three X-ray sources remained unidentified.

X-Ray counts and contribution to the X-ray background of an IR population of starburst and active galaxies

2003 ◽  
Vol 324 (12) ◽  
pp. 170-170 ◽  
Author(s):  
M. Polletta ◽  
C.J. Lonsdale ◽  
C. Xu ◽  
B.J. Wilkes
Keyword(s):  
Active Galaxies ◽  
X Ray ◽  
X Ray Background

scholarly journals The Shape of Soft X-ray Spectra of Quasars

1989 ◽  
Vol 134 ◽  
pp. 175-176
Author(s):  
D. A. Schwartz ◽  
Y. Qian ◽  
W. H. Tucker
Keyword(s):  
Flux Density ◽  
Power Laws ◽  
Seyfert Galaxies ◽  
Background Spectrum ◽  
X Ray ◽  
The Mean ◽  
X Ray Background ◽  
Image Position ◽  
Two Parameters ◽  
Lines Of Evidence

Several lines of evidence suggest that the x-ray spectra of quasars are not simple, exact power laws: 1. when Wilkes and Elvis (1987) analyzed quasars as power laws they found an absorption less than that due to our galaxy; 2. The mean 0.3 to 3.5 keV spectral index is steeper than the mean for the 2 to 20 keV range; 3. although several lines of evidence argue that AGN provide a significant portion (perhaps all) of the x-ray background, the diffuse background spectrum does not agree with the x-ray power-law indices measured for quasars or Seyfert galaxies. Schwartz and Tucker (1988) have suggested that all the above conflicts are reconciled if the slope in the Log(flux density) vs. Log(energy) plot flattens continuously with increasing energy. In this paper we utilize one particular parameterization suggested for the flux density, which we call the “log-slope” model: where f is the flux density, K a normalization parameter which is not of interest here, and a and b are the two parameters of our fit.

scholarly journals Markarian survey and Markarian galaxies

2021 ◽  
pp. 174-185
Author(s):  
A. M. Mickaelian
Keyword(s):  
Seyfert Galaxies ◽  
Active Galaxies ◽  
Optical Identification ◽  
Stellar Objects ◽  
X Ray ◽  
Ir Sources ◽  
Uv Excess ◽  
Objective Prism ◽  
Definition Of

Markarian survey (or the First Byurakan Survey, FBS) was the first systematic survey for active galaxies and was a new method for search for such objects. Until now, it is the largest objective prism survey of the sky (17,000 deg2). It was carried out in 1965-1980 by B. E. Markarian and his colleagues and resulted in discovery of 1517 UV-excess (Markarian) galaxies. They contain many active galaxies, as well as powerful gamma-, X-ray, IR and radio sources (Mrk 180, 231, 421, 501, etc.), BCDGs (Mrk 116) and interacting/merging systems (Mrk 266, 273, etc.). They led to the classification of Seyfert galaxies into Sy1 and Sy2 and the definition of Starbursts (SB). Several catalogs of Markarian galaxies have been published (Bicay et al., 1995, Markarian et al., 1989, Mazzarella & Balzano, 1986, Petrosian et al., 2007) and they are accessible in all corresponding databases. Markarian survey also served as a basis for search for UVX stellar objects (including QSOs and Seyferts), late-type stars and optical identification of IR sources. At present the survey is digitized and DFBS database is available. We review the main characteristics of the Markarian survey, its comparison with other similar surveys and the importance of Markarian galaxies in modern astrophysics.

Very low luminosity active galaxies and the X-ray background

1984 ◽  
Vol 283 ◽  
pp. 479 ◽  
Author(s):  
M. Elvis ◽  
A. Soltan ◽  
W. C. Keel
Keyword(s):  
Active Galaxies ◽  
X Ray ◽  
X Ray Background

X-ray Astronomy and the IR Background

2001 ◽  
Vol 204 ◽  
pp. 335-345
Author(s):  
Richard Mushotzky
Keyword(s):  
Star Formation ◽  
Intergalactic Medium ◽  
Massive Stars ◽  
Active Galaxies ◽  
Infrared Galaxies ◽  
Metal Production ◽  
X Ray ◽  
Luminous Infrared Galaxies ◽  
Early Origin ◽  
X Ray Background

I review the recent Chandra results on the sources of the X-ray background and the X-ray properties of the SCUBA sources. We conclude that 10–20% of the IR background is produced by active galaxies and a similar fraction of the SCUBA sources harbor luminous AGN. Many of the Chandra sources are apparently luminous infrared galaxies themselves, but factors of 2–10 below the SCUBA limits. We summarize the X-ray evidence for metal production in groups and clusters and point out that these data require considerably more star formation than inferred from optical stellar data. The abundance ratios of Fe and Si indicate that much of the metals in groups and clusters was produced by massive stars, and the lack of evolution in Fe out to z ~ 0.5 argues for quite an early origin for the metals. This same process also seems to have injected considerable energy into the gas in groups and clusters, which may have dominated the mechanism of star formation and produced a metal-enriched intergalactic medium

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