A Search for X-Ray Flares from Nearby ‘Normal’ and Active Galaxies: Comparison of ROSAT All-Sky Survey Data with Deep PSPC Fields

2006 ◽  
pp. 300-301
Author(s):  
Stefanie Komossa
Keyword(s):  
Survey Data ◽  
Active Galaxies ◽  
X Ray ◽  
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 Erratum: Properties of the X-ray-brightest Abell-type clusters of galaxies (XBACs) from ROSAT All-Sky Survey data -- I. The sample

1996 ◽  
Vol 283 (3) ◽  
pp. 1103-1104 ◽  
Author(s):  
H. Ebeling ◽  
W. Voges ◽  
H. Bohringer ◽  
A. C. Edge ◽  
J. P. Huchra ◽  
...  
Keyword(s):  
Survey Data ◽  
Clusters Of Galaxies ◽  
X Ray ◽  
Sky Survey

scholarly journals A VO study of SDSS AGNs with X-ray emission from ROSAT-PSPC pointed observations

2006 ◽  
Vol 2 (14) ◽  
pp. 581-581
Author(s):  
Robert J. Hanisch ◽  
Anatoly A. Suchkov ◽  
Timothy M. Heckman ◽  
Wolfgang H. Voges
Keyword(s):  
Survey Data ◽  
Sloan Digital Sky Survey ◽  
Radio Sources ◽  
X Ray ◽  
Sky Survey ◽  
Data Release

We use VO facilities to study AGNs with X-ray emission. We present a sample of 1744 of Type 1 AGNs from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) spectroscopic catalog with X-ray counterparts in the White-Giommi-Angelini catalogue (WGACAT) of ROSAT-pspc pointed observations. Of 1744 X-ray sources, 1410 (80.9%) are new AGN identifications. Of 4,574 SDSS DR4 AGNs for which we found radio matches in the catalogue of radio sources from the Faint Images of the Radio Sky at Twenty (FIRST) cm survey, 224 turned up in our sample of SDSS X-ray AGN.

X-Ray Transients in the SRG/eROSITA All-Sky Survey

2017 ◽  
Vol 14 (S339) ◽  
pp. 145-145
Author(s):  
A. Rau
Keyword(s):  
Survey Data ◽  
Time Domain ◽  
Scanning Strategy ◽  
Telescope Array ◽  
X Ray ◽  
Sky Survey ◽  
Wide Range ◽  
Imaging Telescope

AbstracteROSITA (the extended ROentgen Survey with an Imaging Telescope Array) onboard the Spectrum Roentgen Gamma mission will perform a deep all-sky X-ray survey. During the first four years of operation the satellite will scan the entire sky every once every half year, visiting any position between 8 and 500 times. The eROSITA scanning strategy will test a wide range of times-scales, from seconds to years, and thus provide a powerful window into the X-ray transient and variable sky. This contribution summarised the key science opportunities for time-domain studies with eROSITA, and presented strategies for finding transients in the all-sky survey data.

scholarly journals The Galactic X-ray Halo

1997 ◽  
Vol 166 ◽  
pp. 471-474
Author(s):  
J. Pietz ◽  
J. Kerp ◽  
P.M.W. Kalberla ◽  
W.B. Burton ◽  
Dap Hartmann ◽  
...  
Keyword(s):  
Survey Data ◽  
Intensity Distribution ◽  
X Ray ◽  
The Public ◽  
Sky Survey ◽  
X Ray Background ◽  
Scale Length

AbstractWe analyzed the soft X-ray background (SXRB) source intensity distribution of the ¾ keV and ¼ keV photons by correlating the public ROSAT PSPC All-Sky Survey data with the new Leiden/Dwingeloo HI Survey. We found that the ¾ keV and ¼ keV distant background source intensity distribution can be modelled by an isothermal (T = 1.5.106 K) disk-like (scale length A1 = 15 kpc) X-ray halo in addition to the radiation of the extragalactic X-ray background.

scholarly journals OeBe-stars with possible compact companions observed at X-rays

1995 ◽  
Vol 163 ◽  
pp. 554-558
Author(s):  
E.J.A. Meurs ◽  
A.J.M. Piters
Keyword(s):  
Survey Data ◽  
Detection Rate ◽  
Compact Object ◽  
Detectable Level ◽  
Stellar Winds ◽  
X Rays ◽  
Be Stars ◽  
X Ray ◽  
Level Of Activity ◽  
Sky Survey

A survey of bright O- and B-type stars has been conducted from the ROSAT All Sky Survey data, aiming at the detection of compact companions expected for Oe and Be stars. Concurrent Hα spectroscopy has been used to establish the level of activity of these stars around the time of the X-ray observations. The detection rate of OB and OeBe stars as well as their average X-ray over bolometric luminosities suggest little difference between these two groups of objects. Instead of accretion onto a compact object (NS, WD), the X-ray emission from OeBe stars may be produced by stellar winds as has been proposed for O- and early B-type stars in general. Flexibilities in the available models for X-ray emission from accreting WDs may allow the X-ray emission from such objects to remain below a detectable level. These investigations are now being extended to pointed observations in the ROSAT Archive.

scholarly journals X-ray properties of early-type stars

1994 ◽  
Vol 162 ◽  
pp. 200-201
Author(s):  
Thomas W. Berghöfer ◽  
Jürgen H. M. M. Schmitt
Keyword(s):  
Survey Data ◽  
Early Type ◽  
Late Type ◽  
X Ray ◽  
Sky Survey ◽  
Low Mass ◽  
Early Type Stars ◽  
Einstein Observatory ◽  
Hr Diagram

Extensive stellar surveys with the Einstein Observatory (Chlebowski et al., 1989) and with ROSAT have clearly confirmed the presence of stellar X-ray emission over nearly the whole range of the HR diagram. In the ROSAT all-sky survey data approximately 20000 stellar X-ray sources were detected (Schmitt et al., 1992). Most of these stellar X-ray emitters are low mass late-type stars, the origin of their X-ray emission is thought to be coronal.

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

2019 ◽  
Vol 16 (1) ◽  
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.

Sign in / Sign up

Export Citation Format

Share Document