scholarly journals Spectral Classification of Optical Counterparts toROSATAll-Sky Survey X-Ray Sources

2007 ◽  
Vol 133 (6) ◽  
pp. 2495-2501 ◽  
Author(s):  
Diana Dragomir ◽  
Philippe Roy ◽  
Robert E. Rutledge
Keyword(s):  
Spectral Classification ◽  
X Ray ◽  
Sky Survey

scholarly journals A Survey of X-ray–Emitting IRAS Galaxies: A New Class of Objects or Hidden AGNs?

1997 ◽  
Vol 159 ◽  
pp. 421-422
Author(s):  
M. Dennefeld
Keyword(s):  
Spectral Resolution ◽  
Cross Correlation ◽  
Unexpected Result ◽  
Frequency Of Occurrence ◽  
Spectral Classification ◽  
X Ray ◽  
New Class ◽  
Sky Survey

A cross-correlation between the IRAS PSC and the ROSAT All-Sky Survey has provided 242 sources detected in both surveys (Boiler et al. 1992). About half of these have redshifts in the literature and a spectral classification. An unexpected result was the discovery of many galaxies with X-ray luminosities up to a few 1043 ergs s−1, yet without Seyfert characteristics in their optical spectra (e.g., Boiler et al. 1993). To investigate this problem further and evaluate the frequency of occurrence of these peculiar objects, a spectroscopic follow-up has been undertaken to:• Determine velocities and luminosities for all the unclassified objects.• Reevaluate the classification of high X-ray luminosity objects previously not recognized as Seyferts. In particular, spectral resolution or coverage and variability are important parameters to consider if one wants to detect faint signs of Seyfert activity.

scholarly journals Fine Classification of QSOs and Seyferts for Activity Types Based on SDSS Spectroscopy

2021 ◽  
Vol 7 ◽  
Author(s):  
A. M. Mickaelian ◽  
H. V. Abrahamyan ◽  
G. M. Paronyan ◽  
G. A. Mikayelyan
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Radio Sources ◽  
Spectral Classification ◽  
X Ray ◽  
Activity Types ◽  
Larger Sample ◽  
Variable Radio ◽  
Fine Classification

Using the SDSS spectroscopy, we have carried out fine optical spectral classification for activity types for 710 AGN candidates. These objects come from a larger sample of some 2,500 candidate AGN using pre-selection by various samples; bright objects of the Catalog of Quasars and Active Galactic Nuclei, AGN candidates among X-ray sources, optically variable radio sources, IRAS extragalactic objects, etc. A number of papers have been published with the results of this spectral classification. More than 800 QSOs have been identified and classified, including 710 QSOs, Seyferts and Composites. The fine classification shows that many QSOs show the same features as Seyferts, i.e., subtypes between S1 and S2 (S1.2, S1.5, S1.8 and S1.9). We have introduced subtypes for the QSOs: QSO1.2, QSO1.5, QSO1.8, QSO1.9, though the last subtype does not appear in SDSS wavelength range due to mostly highly redshifted Hα (the main line for identification of the 1.9 subtype). Thus, independent of the luminosity (which serves as a separator between QSOs and Seyferts), AGN show the same features. We also have classified many objects as Composites, spectra having composite characteristics between Sy and LINERs, Sy and HII or LINERs and HII; in some cases all three characteristics appear together resulting as Sy/LINER/HII subtype. The QSOs subtypes together with Seyfert ones allow to follow AGN properties along larger redshift range expanding our knowledge on the evolution of AGN to more distant Universe represented by QSOs.

scholarly journals Activity types of galaxies selected from HRC/BHRC sample

2018 ◽  
pp. 412-416
Author(s):  
G. M. Paronyan ◽  
A. M. Mickaelian ◽  
H. V. Abrahamyan ◽  
G. A. Mikayelyan
Keyword(s):  
Spectral Classification ◽  
Direct Examination ◽  
X Ray ◽  
Activity Types

In this study we carry out detailed spectral classification of 123 AGN candidates from the Joint HRC/BHRC sample, which is a combination of HRC (Hamburg-ROSAT Catalogue) and BHRC (Byurakan-Hamburg-ROSAT Catalogue). These objects were revealed as optical counterparts for ROSAT X-ray sources, however spectra for 123 of them are given in SDSS-III, IV without definite spectral classification. We studied these 123 objects using the SDSS spectra and revealed the detailed activity types for them. Three diagnostic diagrams and direct examination of the spectra were used to have more confident classification. We also made identification of these sources in other wavelength ranges and calculated some of their parameters.

X-ray spectral classification of supernova remnants in the Large Magellanic Cloud

1982 ◽  
Vol 255 ◽  
pp. 440 ◽  
Author(s):  
D. H. Clark ◽  
I. R. Tuohy ◽  
M. A. Dopita ◽  
D. S. Mathewson ◽  
K. S. Long ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Spectral Classification ◽  
X Ray

X-ray Loud AGN with Optical Starburst or Seyfert 2 Properties

1994 ◽  
Vol 159 ◽  
pp. 365-365
Author(s):  
N. Bade ◽  
S. Schaeidt
Keyword(s):  
Emission Line ◽  
Large Area ◽  
X Ray ◽  
Detailed Classification ◽  
Sky Survey ◽  
Emission Line Spectrum ◽  
Objective Prism ◽  
Calar Alto

The Hamburg Sternwarte is conducting a large area identification program of ROSAT All Sky Survey (RASS) sources on objective prism plates taken with the Schmidt telescopes on Calar Alto and La Silla (Bade et al., 1992, MPE-Report 235, 377). With follow-up observations redshifts and a more detailed classification of the emission line spectrum of 284 AGN were derived until August 1992.

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