Seyfert Type 1 galaxies observed with the HEAO 1 scanning modulation collimator

1980 ◽  
Vol 235 ◽  
pp. 355 ◽  
Author(s):  
R. G. Dower ◽  
H. V. Bradt ◽  
R. E. Doxsey ◽  
M. D. Johnston ◽  
R. E. Griffiths
Keyword(s):  
Modulation Collimator ◽  
Seyfert Type

scholarly journals Observations of Type 1 Seyfert galaxies with the HEAO-1 scanning modulation collimator

1979 ◽  
Vol 188 (4) ◽  
pp. 813-817 ◽  
Author(s):  
R. E. Griffiths ◽  
U. Briel ◽  
D. A. Schwartz ◽  
J. Schwarz ◽  
R. E. Doxsey ◽  
...  
Keyword(s):  
Seyfert Galaxies ◽  
Modulation Collimator

scholarly journals The Extragalactic X-Ray and γ-ray Backgrounds

1990 ◽  
Vol 139 ◽  
pp. 345-356
Author(s):  
G. Setti
Keyword(s):  
Big Bang ◽  
Prima Facie ◽  
Baryon Density ◽  
Primordial Nucleosynthesis ◽  
X Ray ◽  
Γ Ray ◽  
X Ray Background ◽  
Seyfert Type ◽  
Number Of Authors

The long-standing problem of the origin of the extragalactic X-ray background (XRB) is reviewed. Although the shape of the spectrum in the 3–100 keV interval is suggestive of an optically thin bremsstrahlung at ~ 40 keV, the interpretation in terms of a hot intergalactic gas (IGG) requires a rather extreme energy supply and a gas density conflicting with the baryon density upper limit derived from primordial nucleosynthesis calculations in the standard hot big-bang model. A summary discussion of the estimated contributions from the integrated X-ray emission of known classes of extragalactic discrete sources at a reference energy of 2 keV is given. Although these estimates are still uncertain, the subtraction of a “minimum” contribution drastically modifies the 40 keV thermal shape, which is the prima facie evidence of a hot IGG. AGNs are the main contributors. Low luminosity AGNs (Seyfert type 1 nuclei) at redshift z = 1 − 2 may in fact saturate the 2 keV XRB, but their observed hard X-ray spectra are on the average unlike (much too steep) that of the XRB. This has led a number of authors to postulate new classes of sources and some exotic models which are briefly summarized. However, if a recently proposed unified scheme of AGNs holds, then the bulk of the XRB intensity can be explained independently of the observed spectral differences and with a mild cosmological evolution. The origin of the extragalactic γ-ray background is briefly commented upon in the concluding remarks.

scholarly journals The host galaxies of Seyfert type 1 nuclei

1994 ◽  
Vol 266 (4) ◽  
pp. 953-971 ◽  
Author(s):  
J. K. Kotilainen ◽  
M. J. Ward
Keyword(s):  
Host Galaxies ◽  
Seyfert Type

scholarly journals Recent X-Ray Observations of Seyferts and Emission-Line Galaxies

1980 ◽  
Vol 5 ◽  
pp. 641-651 ◽  
Author(s):  
R. E. Griffiths
Keyword(s):  
Average Error ◽  
X Ray ◽  
The Past ◽  
Sky Survey ◽  
Emission Line Galaxies ◽  
Modulation Collimator ◽  
Using Data ◽  
Seyfert Nucleus ◽  
Einstein Observatory

It has been just a few years since Type 1 Seyferts were established as a class of X-ray sources with luminosities in the range 1042 - 1045 ergs s-1 by Elvis et al. (1978) using data from the sky survey instrument on Ariel V, and by Tananbaum et al. (1978) using data from UHURU.The average error-box sizes for X-ray sources identified with Type 1 Seyferts in the 2A catalog (Cooke et al. 1978) is ˜ 0.4 sq. degrees, and ˜ 1.0 sq. degrees for those in the 4U catalog (Forman et al. 1978). Improvement in these positions has been made over the past two years by the modulation collimators on board the satellites SAS-3 and HEAO-1. In particular, the HEAO-1 scanning modulation collimator has been used to position a total of 20 X-ray sources, confirming the identification in each case, with the possible exception of Mkn 279 (Dower et al. 1979, Griffiths et al. 1979a). Of the 37 X-ray sources which were discovered prior to the launch of the Einstein Observatory and which have been associated with Type 1 Seyferts, 21 have been positioned to ˜ 1 arc minute, representing an improvement by factors of ˜ 20 to 100 over the previous 2A and 4U error box sizes. Some examples of the error boxes and identifications confirmed with the HEAO-1 scanning modulation collimator are shown in figs. 1 and 2. In fig. 1 both NGC 7213 (Philips 1979) and MCG - 2 - 58 - 22 (Ward et al. 1978) were discovered to be Seyferts by optical spectroscopy of candidate objects in the error regions of the corresponding X-ray sources. NGC 7213 is a Seyfert nucleus in a galaxy of Type SO (Philips 1979). In fig. 2, NGC 931 was likewise discovered to be a Seyfert as a result of its X-ray emission (Ward and Wilson 1978).

scholarly journals Compton reflection and iron fluorescence in BeppoSAX observations of Seyfert type 1 galaxies

2002 ◽  
Vol 389 (3) ◽  
pp. 802-811 ◽  
Author(s):  
G. C. Perola ◽  
G. Matt ◽  
M. Cappi ◽  
F. Fiore ◽  
M. Guainazzi ◽  
...  
Keyword(s):  
Seyfert Type

scholarly journals Determination of the Magnetic Field Strength and Geometry in the Accretion Disks of AGNs by Optical Spectropolarimetry

Universe ◽  
2021 ◽  
Vol 7 (6) ◽  
pp. 202
Author(s):  
Mikhail Piotrovich ◽  
Stanislava Buliga ◽  
Tinatin Natsvlishvili
Keyword(s):  
Magnetic Field ◽  
Accretion Disk ◽  
Accretion Disks ◽  
Degree Of Polarization ◽  
Special Astrophysical Observatory ◽  
Average Value ◽  
Seyfert Type ◽  
The Magnetic Field

Based on the spectropolarimetric data of 33 Seyfert type 1 galaxies observed with the BTA-6m telescope of the Special Astrophysical Observatory, we estimated the magnetic field values at the event horizon of the supermassive black hole BH and the exponents of the power-law dependence s of the magnetic field on the radius. We used the model of optically thick geometrically thin Shakura–Sunyaev accretion disk. The average value of logBH[G] was found to be ∼4, which is in good agreement with the results obtained by other methods. The average value of s is s≈1.7, and its distribution maximum span is in the range od 1.85<s<2.0. This is a rather interesting result, since s=5/4 is usually adopted in calculations for Shakura–Sunyaev accretion disks. In addition, for two objects PG 1545+210 and 2MASX J06021107+2828382, the measured degree of polarization is greater than the maximum possible value at the angle between the line of sight and the axis of the accretion disk i=45°. It was concluded that for these objects the angle should be closer to i=60°.

Extragalactic X-ray observations - The 2A catalogue and supplementary results from the Ariel 5 sky survey

1979 ◽  
Vol 366 (1726) ◽  
pp. 375-390 ◽  
Keyword(s):  
Radio Galaxies ◽  
Status Report ◽  
Galactic Latitude ◽  
Clusters Of Galaxies ◽  
X Ray ◽  
Major Class ◽  
Sky Survey ◽  
Emission Line Galaxies ◽  
Seyfert Type

A status report is given on the Ariel 5 sky survey for X -ray sources at galactic latitude | b | ≽ 10°. The operation of the sky survey instrument (s. s. i.) is briefly reviewed and the production of the recently published 2A catalogue of X -ray sources is described. A remarkably high percentage ( ca . 75%) of the 105 sources in the 2A catalogue have now been identified with extragalactic, or, in a few cases, galactic, counterparts, and this is attributed to the improved location of sources (cf. the earlier 3U catalogue), and the strong correlation with optically bright or outstanding objects. The 2A catalogue and subsequent studies have established active galaxies, especially of the Seyfert type 1, to be a major class of powerful X -ray emitter. Present members of this class, which also includes a number of emission line galaxies, radio galaxies and quasars, are listed and their basic X -ray properties reviewed. The second major class of extragalactic X -ray source, clusters of galaxies, first established with the Uhuru satellite, has been substantially extended by Ariel 5. This work also is briefly reviewed. Finally, additional X -ray data from the s. s. i. (still operative) is being used to revise and add to the 2A catalogue. Several examples of this more recent work are given, together with an estimate of the expected content of the final s. s. i. catalogue when the mission is terminated (now planned for October 1979).

Crystalloid Inclusions in Hepatocyte Mitochondria and Their Similarity to Cytoplasmic Crystalloids

1974 ◽  
Vol 32 ◽  
pp. 198-199
Author(s):  
Odell T. Minick ◽  
Hidejiro Yokoo
Keyword(s):  
Liver Disease ◽  
Alcoholic Liver Disease ◽  
Special Interest ◽  
Structural Variations ◽  
Mitochondrial Alterations ◽  
The Matrix ◽  
Crystalloid Inclusions ◽  
Liver Biopsies

Mitochondrial alterations were studied in 25 liver biopsies from patients with alcoholic liver disease. Of special interest were the morphologic resemblance of certain fine structural variations in mitochondria and crystalloid inclusions. Four types of alterations within mitochondria were found that seemed to relate to cytoplasmic crystalloids.Type 1 alteration consisted of localized groups of cristae, usually oriented in the long direction of the organelle (Fig. 1A). In this plane they appeared serrated at the periphery with blind endings in the matrix. Other sections revealed a system of equally-spaced diagonal lines lengthwise in the mitochondrion with cristae protruding from both ends (Fig. 1B). Profiles of this inclusion were not unlike tangential cuts of a crystalloid structure frequently seen in enlarged mitochondria described below.

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