Active galaxies observed during the Extreme Ultraviolet Explorer all-sky survey

1995 ◽  
Vol 439 ◽  
pp. 90 ◽  
Author(s):  
H. L. Marshall ◽  
A. Fruscione ◽  
T. E. Carone
Keyword(s):  
Extreme Ultraviolet ◽  
Active Galaxies ◽  
Sky Survey

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.

Studying the Flux Density of Bright Active Galaxies at Different Spectral Bands

2019 ◽  
Vol 16 (1(Suppl.)) ◽  
pp. 0230
Author(s):  
Rashed Et al.
Keyword(s):  
Flux Density ◽  
Galactic Nuclei ◽  
Absolute Magnitude ◽  
Active Galaxies ◽  
X Ray ◽  
Spectral Bands ◽  
Sky Survey ◽  
Multi Wavelength ◽  
Statistical Studies ◽  
Density Ratios

Statistical studies are reported in this article for an active galactic nuclei sample of different type of active galaxies Seyferts 1, Seyferts 2, and Quasars. These sources have been selected from a Catalogue for bright X-ray galaxies. The name of this index is ROSAT Bright Source Catalogue (RBSC) and the NRAO VLA Sky Survey (NVSS). In this research, multi-wavelength observational bands Radio at 1.4 GHz, Optical at 4400 A0, and X-ray at energy 0.1-2.4 KeV have been adopted in this study. The behavior of flux density ratios has been studied ,  with respect to the absolute magnitude . Furthermore, the Seyfert1 and Seyfert 2 objects are combined in one group and the QSOs are collectest in another group. Also, it has been found that the ratios , are increasing towards fainter optical absolute magnitude especially in Quasars.

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.

scholarly journals The Extreme Ultraviolet Explorer Mission

1992 ◽  
Vol 9 ◽  
pp. 247-254 ◽  
Author(s):  
Stuart Bowyer ◽  
Patrick Jelinsky ◽  
Carol Christian ◽  
Isabel Hawkins
Keyword(s):  
Extreme Ultraviolet ◽  
Variable Line ◽  
Explorer Mission ◽  
Sky Survey ◽  
International Ultraviolet Explorer ◽  
Line Space ◽  
Made In

AbstractThe Extreme Ultraviolet Explorer mission is described. For the first six months, an all-sky survey will be carried out covering 90 to 750 Å, or essentially the entire extreme ultraviolet (EUV) bandpass. This EUV survey will be made in four bands, or colors: λλ 90-150 Å, 170-250 Å, 400-600 Å, and 550-750 Å. A portion of the sky which is free from the normally intense 304 Å geocoronal helium background will be surveyed at greater sensitivity; the wavelength coverage of this band is from 90 to 400 Å. Following the sky survey portion of the mission, spectroscopy of individual sources will be carried out. Three spectrometers employing novel variable line-space gratings will provide spectra with ~1 Å resolution over the band from 70 to 760 Å. This spectroscopy will be carried out by guest observers chosen by NASA in a manner roughly analogous to the International Ultraviolet Explorer (IUE) guest observer program.

scholarly journals Rosat WFC EUV Observations of Ab Dor (And other Local Group Stars)

1993 ◽  
Vol 137 ◽  
pp. 658-661
Author(s):  
Barry J. Kellett ◽  
Gordon E. Bromage
Keyword(s):  
Energy Range ◽  
Local Group ◽  
Extreme Ultraviolet ◽  
Broad Band ◽  
Full Description ◽  
Wide Field ◽  
Late Type ◽  
Rutherford Appleton Laboratory ◽  
Sky Survey ◽  
The Uk

The Rosat Observatory was launched on June 1st, 1990, and after a brief Performance Verification phase, performed an almost complete sky survey. One of the two main telescopes on the Observatory is the UK Wide Field Camera (WFC). The WFC is the first extreme ultraviolet (EUV) instrument to survey the whole sky, and during the survey detected several hundred active late-type stars.The WFC (Wells et al., 1990) was built by a consortium of five UK institutes, four Universities and the Rutherford Appleton Laboratory. During the all-sky survey, two filters were used. These allow broad-band photometry to be performed. The SIA filter (lexan/carbon/boron) and S2A filter (lexan/beryllium) were alternated on a one day basis. The SIA filter covers the energy range 0.085-0.180 KeV, centred on 0.124 KeV, while the softer S2A filter covers the range 0.070-0.110 KeV (centred on 0.090 KeV) (10% efficiency) [see Kent et al. (1990) for a full description of the WFC filters].

scholarly journals Observations of AGN with the Extreme Ultraviolet Explorer

1994 ◽  
Vol 159 ◽  
pp. 105-110
Author(s):  
Herman L. Marshall
Keyword(s):  
Power Law ◽  
Extreme Ultraviolet ◽  
Active Galaxies ◽  
Spectral Features ◽  
Bl Lac Objects ◽  
X Ray ◽  
Difficult Time ◽  
Bl Lac ◽  
First Results ◽  
Galactic Sources

The first results from surveys performed in the extreme ultraviolet (EUV) will be described in the context of studies of active galaxies and BL Lac objects. About a dozen extra-galactic sources are known so far to emit sufficient EUV radiation that they are detectable even through the Galactic interstellar medium. These results are interpreted in the context of a model of EUV or soft X-ray excesses in the case of AGN. In the case of BL Lac objects, the detections indicate that the steep soft X-ray power law spectra continue into the EUV and that there is little intrinsic gas. Finally, there now exists EUV spectra from the Extreme Ultraviolet Explorer for one BL Lac, PKS 2155-304 and two AGN: Mk 478 and NGC 5548. The spectra show no significant spectral features; for AGN, it indicates that optically thin and emission line models may have a difficult time explaining the EUV and soft X-ray bumps.

scholarly journals X-Ray Selected EUV Galaxies: A Quest for the Faintest Extragalactic EUV Sources

1996 ◽  
Vol 152 ◽  
pp. 69-73
Author(s):  
Antonella Fruscione
Keyword(s):  
Extreme Ultraviolet ◽  
X Ray ◽  
The Public ◽  
Euv Emission ◽  
Sky Survey ◽  
Using Data ◽  
First Time

Using data from the public archive of the Extreme Ultraviolet Explorer (EUVE) all-sky survey, we have systematically searched for extreme ultraviolet (EUV) emission (58-174 Å, 0.07-0.21 keV) around approximately 2500 distinct positions in the sky corresponding to known X-ray emitting extragalactic sources. We find that 20 X-ray galaxies are EUV bright and were detected with significance above 4 σ during the EUVE survey: 8 are reported here for the first time (MS 0037.7−0156, Mrk 142, M 65, EXO 1128.1+6908, M 87, Mrk 507, PKS 2005–489 and 1H 2351−315.A). 68 additional galaxies are detected with a lower significance (3 < σ < 4), but the list is affected by a high percentage of spurious sources.

scholarly journals Temporal Behaviour of Sources in the ROSAT Extreme-Ultraviolet All-Sky Survey

1996 ◽  
Vol 152 ◽  
pp. 15-19
Author(s):  
Paul McGale ◽  
J.P. Pye ◽  
C.R. Barber ◽  
C.G. Page
Keyword(s):  
Extreme Ultraviolet ◽  
Cataclysmic Variables ◽  
Eclipsing Binaries ◽  
High Mass ◽  
Late Type ◽  
Temporal Behaviour ◽  
Source Type ◽  
Luminosity Functions ◽  
Sky Survey ◽  
M Stars

From a total catalogue of 479 2RE sources, 31 have been found to be variable. All the variable sources are optically identified, with a breakdown by source type as follows: cataclysmic variables 9, late-type (F-M) stars 18, the high-mass X-ray binary Her X-1, the eclipsing binaries Algol and V471 Tau, and the active galaxy Mkn 478. The most highly variable objects in the EUV band are cataclysmic variables. The survey was sensitive to timescales from ~ 1.5 h to ~ 5 d, and observed variability ranges from flare-like events lasting < 1.5 h to irregular and periodic flux changes over ~ 0.5–2 d. With the exception of the cataclysmic variables, and possibly a few late-type dK-dMe stars with large flares, the observed variability levels should not substantially affect EUV luminosity functions

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