ROSAT All-Sky Survey observations of IRAS galaxies

Boller, Th.; Bertoldi, F.; Dennefeld, M.; Voges, W.

doi:10.1051/aas:1998397

Cited by 37 publications

(37 citation statements)

References 10 publications

(16 reference statements)

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“…This galaxy has been identified with the radiosource 5C 3.100 (Antonucci 1985) and a ROSAT X-ray source (Boller et al 1998). Dahari & de Robertis (1988) called it a Seyfert 2.…”

Section: Notes On Individual Objectsmentioning

confidence: 98%

AGNs with composite spectra

Gonçalves

Véron-Cetty

Véron

1999

Astron. Astrophys. Suppl. Ser.

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Abstract. In a previous paper (Véron et al. 1997) we presented medium resolution (3.4Å F W HM) spectroscopic observations of 15 "transition objects", selected for having an ambiguous location in the Veilleux & Osterbrock (1987) diagnostic diagrams, and showed that most of them were in fact "composite", this being due to the simultaneous presence on the slit of both a Seyfert or Liner nucleus and a H ii region. Here, we report new spectroscopic observations of 53 emission-line galaxies with a "transition" spectrum, bringing up to 61 the total number of observed objects in an unbiased sample of 88 "transition objects". Almost all of the observed galaxies have a "composite" nature, confirming the finding that true "transition" spectra may not exist at all.By eliminating "composite objects" from the diagnostic diagrams, a clear separation between the different classes of nuclear emission-line regions (Seyfert 2s, Liners and H ii regions) becomes apparent; by restricting the volume occupied by the different line-emitting regions in the 3-dimensional diagnostic diagrams, we are also restricting the range of possible physical parameters in these regions. There seems to be no continuity between Seyfert 2s and Liners, the two classes occupying distinct volumes in the 3-dimensional space defined by λ5007/Hβ, λ6583/Hα, and λ6300/Hα.

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“…This galaxy has been identified with the radiosource 5C 3.100 (Antonucci 1985) and a ROSAT X-ray source (Boller et al 1998). Dahari & de Robertis (1988) called it a Seyfert 2.…”

Section: Notes On Individual Objectsmentioning

confidence: 98%

AGNs with composite spectra

Gonçalves

Véron-Cetty

Véron

1999

Astron. Astrophys. Suppl. Ser.

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“…The IRAS position marked in Fig. 2 is α 2000 =22h18m03.3 and δ 2000 = −59 • 40 58 (Boller et al 1997b). So either the faint object 10 north of the IRAS position or object #4 in Fig.…”

Section: Other Wavelength Rangesmentioning

confidence: 98%

RX J2217.9-5941: A highly X-ray variable Narrow-Line Seyfert1 galaxy

Grupe

Thomas

Leighly

2001

A&A

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Abstract. We report the discovery of a highly X-ray variable AGN, RX J2217.9-5941. This object was bright during the ROSAT All-Sky Survey (RASS), during which a decrease in the count rate by a factor of 12 was observed. It was found to be much fainter in follow-up HRI observations and is therefore an X-ray transient AGN candidate. On long time scales of years, its count rate decreased by a factor of about 30 between the RASS and the ROSAT HRI and ASCA observations in 1998. Analysis of the ASCA data, complicated by source confusion and poor statistics, tentatively indicates a steep spectrum in the faint state. There is no evidence for variability among 5 optical observations of the object obtained between 1992 and 1998. We discuss the variability of RX J2217.9-5941 and its possible X-ray transient nature.

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“…Bade et al (1995) presented a cross correlation between the RASS and the Hamburg Quasar Survey and found 225 AGN in total, of which 55 fulfilled they criteria to be NLS1 (=25%). Grupe et al (1998aGrupe et al ( , 1999a) used bright soft X-ray selected AGN (for selection criteria see Thomas et al 1998) based on the ROSAT Bright Source Catalogue (Voges et al 1998). The result was that out of the 76 objects of the sample, 25 were NLS1 using the strict criteria, and 32 if the criteria are more relaxed.…”

Section: X-ray Selected Agn Samplesmentioning

confidence: 99%

Statistical properties of narrow-line Seyfert 1 galaxies

Grupe

2000

New Astronomy Reviews

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The number of publications considering Narrow-Line Seyfert 1 galaxies has increased dramatically in recent years. Especially after the launch of the X-ray missions ROSAT and ASCA, Narrow-Line Seyfert 1s have become very popular. In these proceedings I will give an overview of how they are distributed over the electromagnetic spectrum. I will describe what we know about them at radio, infrared, optical, and X-ray bands, and how they differ and how they are similar to Broad-Line Seyfert 1s. Finally I will introduce a method to find them with high probability.

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ROSAT All-Sky Survey observations of IRAS galaxies

Cited by 37 publications

References 10 publications

AGNs with composite spectra

AGNs with composite spectra

RX J2217.9-5941: A highly X-ray variable Narrow-Line Seyfert1 galaxy

Statistical properties of narrow-line Seyfert 1 galaxies

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