Radio‐loud Active Galaxies in the Northern ROSAT All‐Sky Survey. III. New Spectroscopic Identifications from the RASS–Green Bank BL Lacertae Survey

1998 ◽  
Vol 118 (1) ◽  
pp. 127-175 ◽  
Author(s):  
S. A. Laurent‐Muehleisen ◽  
R. I. Kollgaard ◽  
R. Ciardullo ◽  
E. D. Feigelson ◽  
W. Brinkmann ◽  
...  
Keyword(s):  
Active Galaxies ◽  
Bl Lacertae ◽  
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.

scholarly journals Constraints on Lorentz invariance and CPT violation using optical photometry and polarimetry of active galaxies BL Lacertae and S5 B0716+714

2019 ◽  
Vol 99 (3) ◽  
Author(s):  
Andrew S. Friedman ◽  
David Leon ◽  
Kevin D. Crowley ◽  
Delwin Johnson ◽  
Grant Teply ◽  
...  
Keyword(s):  
Lorentz Invariance ◽  
Active Galaxies ◽  
Cpt Violation ◽  
Optical Photometry ◽  
Bl Lacertae

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 Frequency Dependence of the Parsec-scale Polarization Structures of BL Lac Objects

2001 ◽  
Vol 205 ◽  
pp. 140-141
Author(s):  
A.B. Pushkarev ◽  
D.C. Gabuzda ◽  
T.V. Cawthorne
Keyword(s):  
Line Emission ◽  
Galactic Nuclei ◽  
Optical Emission ◽  
Bl Lac Objects ◽  
Bl Lacertae ◽  
Sky Survey ◽  
Radiation Sources ◽  
Wide Wavelength Range ◽  
Bl Lac ◽  
5 Ghz

BL Lacertae objects are active galactic nuclei with weak or undetectable line emission and strong variability in total intensity and linear polarization over a wide wavelength range from optical to radio. The radio emission and much of the optical emission is believed to be synchrotron radiation. Sources in the complete sample of BL Lac objects defined by Kühr and Schmidt (1990) have: 5 GHz fluxes of at least 1 Jy, radio spectral index α ≥ −0.5 (Sv ˜ v+α), rest frame equivalent width of the strongest emission lines less than 5 Å, and optical counterparts on the Sky Survey plates with brightness greater than 20m.

scholarly journals Optically Identified BL Lacertae Objects from the Sloan Digital Sky Survey

2005 ◽  
Vol 129 (6) ◽  
pp. 2542-2561 ◽  
Author(s):  
Matthew J. Collinge ◽  
Michael A. Strauss ◽  
Patrick B. Hall ◽  
Željko Ivezić ◽  
Jeffrey A. Munn ◽  
...  
Keyword(s):  
Sloan Digital Sky Survey ◽  
Bl Lacertae Objects ◽  
Bl Lacertae ◽  
Sky Survey

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

scholarly journals Properties of active galaxies at the extreme of Eigenvector 1

2018 ◽  
Vol 613 ◽  
pp. A38 ◽  
Author(s):  
M. Śniegowska ◽  
B. Czerny ◽  
B. You ◽  
S. Panda ◽  
J.-M. Wang ◽  
...  
Keyword(s):  
Black Hole ◽  
Measurement Errors ◽  
Active Galaxies ◽  
Sloan Digital Sky Survey ◽  
Black Hole Mass ◽  
Formal Parameter ◽  
Sky Survey ◽  
Open Issue ◽  
Uniform Group

Context. Eigenvector 1 (EV1) is the formal parameter which allows the introduction of some order in the properties of the unobscured type 1 active galaxies. Aims. We aim to understand the nature of this parameter by analyzing the most extreme examples of quasars with the highest possible values of the corresponding eigenvalues RFe. Methods. We selected the appropriate sources from the Sloan Digital Sky Survey (SDSS) and performed detailed modeling, including various templates for the Fe II pseudo-continuum and the starlight contribution to the spectrum. Results. Out of 27 sources with RFe larger than 1.3 and with the measurement errors smaller than 20% selected from the SDSS quasar catalog, only six sources were confirmed to have a high value of RFe, defined as being above 1.3. All other sources have an RFe of approximately 1. Three of the high RFe objects have a very narrow Hβ line, below 2100 km s−1 but three sources have broad lines, above 4500 km s−1, that do not seem to form a uniform group, differing considerably in black hole mass and Eddington ratio; they simply have a very similar EW([OIII]5007) line. Therefore, the interpretation of the EV1 remains an open issue.

Erratum: "Optically Identified BL Lacertae Objects from the Sloan Digital Sky Survey" ([URL ADDRESS="/cgi-bin/resolve?2005AJ....129.2542C" STATUS="OKAY"]AJ, 129, 2542 [2005][/URL])

2006 ◽  
Vol 131 (6) ◽  
pp. 3135
Author(s):  
Matthew J. Collinge ◽  
Michael A. Strauss ◽  
Patrick B. Hall ◽  
Željko Ivezić ◽  
Jeffrey A. Munn ◽  
...  
Keyword(s):  
Sloan Digital Sky Survey ◽  
Bl Lacertae Objects ◽  
Bl Lacertae ◽  
Sky Survey
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