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Titolo: The X-ray spectra of optically selected Seyfert 2 galaxies: are there any Seyfert 2 galaxies with no absorption?
Autore: Pappa, A; Georgantopoulos, I; Stewart, GC; Zezas, AL;
- Indirizzi:
- Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England UnivLeicester Leicester Leics England LE1 7RH er LE1 7RH, Leics, England Natl Observ Athens, Inst Astron & Astrophys, Athens, Greece Natl Observ Athens Athens Greece nst Astron & Astrophys, Athens, Greece
- Titolo Testata:
- MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
fascicolo: 3,
volume: 326,
anno: 2001,
pagine: 995 - 1006
- SICI:
- 0035-8711(20010921)326:3<995:TXSOOS>2.0.ZU;2-9
- Fonte:
- ISI
- Lingua:
- ENG
- Soggetto:
- ACTIVE GALACTIC NUCLEI; EMISSION-LINE REGIONS; LOW-LUMINOSITY; ASCA OBSERVATIONS; NEARBY GALAXIES; M51 NGC-5194; ACCRETION; MULTIWAVELENGTH; CONSTRAINTS; MODEL;
- Keywords:
- galaxies : active; galaxies : Seyfert; galaxies : starburst; X-rays : galaxies;
- Tipo documento:
- Article
- Natura:
- Periodico
- Settore Disciplinare:
- Physical, Chemical & Earth Sciences
- Citazioni:
- 56
- Recensione:
- Indirizzi per estratti:
- Indirizzo: Pappa, A Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HT, Midlothian, Scotland Royal Observ Blackford Hill Edinburgh Midlothian ScotlandEH9 3HT
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- Citazione:
- A. Pappa et al., "The X-ray spectra of optically selected Seyfert 2 galaxies: are there any Seyfert 2 galaxies with no absorption?", M NOT R AST, 326(3), 2001, pp. 995-1006
Abstract
We present an X-ray spectral analysis of a sample of eight bona fide Seyfert 2 galaxies, selected on the basis of their high [O III]lambda 5007 flux,from the Ho et al. spectroscopic sample of nearby galaxies. We find that, in general, the X-ray spectra of our Seyfert 2 galaxies are complex, with some of our objects having spectra different from the 'typical' spectrum of X-ray selected Seyfert 2 galaxies. Two (NGC 3147 and 4698) show no evidencefor intrinsic absorption. We suggest that this is a result of the fact that when the torus suppresses the intrinsic medium and hard energy flux, underlying emission from the host galaxy, originating in circumnuclear starbursts, and scattering from warm absorbers contributes in these energy bands more significantly. Our ASCA data alone cannot discriminate whether low-absorption objects are Compton-thick active galactic nuclei (AGNs) with a strongscattered component or lack an obscuring torus. The most striking example of our low absorption Seyfert 2 is NGC 4698. Its spectrum could be explained by either a dusty warm absorber or a lack of broad-line clouds so that its appearance as a Seyfert 2 is intrinsic and not a result of absorption.
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Documento generato il 24/05/13 alle ore 18:17:54