Visibility of scattered broad-line emission in Seyfert 2 galaxies

Heisler, Charlene A.; Lumsden, S. L.; Bailey, Jeremy

doi:10.1038/385700a0

Cited by 145 publications

(227 citation statements)

References 22 publications

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“…warmer infrared color for HBLR objects has been noted in numerous previous studies (e.g., Hutchings & Neff 1991;Heisler et al 1997;Tran et al 1999;Gu, Maiolino, & DultzinHacyan 2001). If all S2 galaxies are intrinsically similar, there is no a priori reason for them to lie in such distinct regions of Figure 1.…”

Section: Observations and Resultsmentioning

confidence: 80%

“…Heisler et al (1997) suggested that S f 20 cm 25 the scattering may take place very close to the nucleus, in the inner "throat" of the torus, and non-HBLR S2 galaxies are perhaps those with the torus axes tipped at larger inclinations, resulting in higher obscuration of the nucleus and greater obstruction of the scattering region.…”

Section: Observations and Resultsmentioning

confidence: 99%

“…Several polarimetric surveys have attempted to address some of these questions (Miller & Goodrich 1990;Kay 1994;Heisler, Lumsden, & Bailey 1997;Moran et al 2000). Common problems often faced include (1) severe biases in the polarized galaxy sample-to maximize the use of telescope time, most early spectropolarimetric targets were chosen simply because they were known to be polarized; and (2) the number of objects being too small for statistical study-since polarimetric observations are time-consuming and tedious, it is difficult to find a suitably large sample of S2 galaxies with HBLRs.…”

Section: Introductionmentioning

confidence: 99%

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Hidden Broad-Line Seyfert 2 Galaxies in the C[CLC]f[/CLC]A and 12 μ[CLC]m[/CLC] Samples

Tran

2001

The Astrophysical Journal

177

230

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We report the results of a spectropolarimetric survey of the CfA and 12 mm samples of Seyfert 2 (S2) galaxies. Polarized (hidden) broad-line regions (HBLRs) are confirmed in a number of galaxies, and several new cases (F02581Ϫ1136, MCG Ϫ3-58-7, NGC 5995, NGC 6552, NGC 7682) are reported. The 12 mm S2 galaxy sample shows a significantly higher incidence of HBLRs (50%) than its CfA counterpart (30%), suggesting that the latter may be incomplete in hidden active galactic nuclei. Compared to the non-HBLR S2 galaxies, the HBLR S2 galaxies display distinctly higher radio power relative to their far-infrared output and hotter dust temperature as indicated by the color. However, the level of obscuration is indistinguishable between the two types of S2 f /f 25 60 galaxies. These results strongly support the existence of two intrinsically different populations of S2 galaxies: one harboring an energetic, hidden S1 nucleus with a broad-line region and the other a "pure" S2 galaxy, with a weak or absent S1 nucleus and a strong, perhaps dominating starburst component. Thus, the simple purely orientation-based unification model is not applicable to all Seyfert galaxies.

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Section: Observations and Resultsmentioning

confidence: 80%

Section: Observations and Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hidden Broad-Line Seyfert 2 Galaxies in the C[CLC]f[/CLC]A and 12 μ[CLC]m[/CLC] Samples

Tran

2001

The Astrophysical Journal

177

230

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“…Heisler et al 1997), although such surveys are probably biased since pre-selection was done according to the broadband polarization.…”

Section: Introductionmentioning

confidence: 99%

Nuclear obscuration and scattering in Seyfert 2 galaxies

Maiolino

Dultzin‐Hacyan

2001

A&A

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Abstract. We study the relation between gaseous absorbing column density (N H ), infrared colors and detectability of the broad lines in a large sample of Seyfert 2 galaxies(Sy2s). We confirm that Sy2s without polarized broad lines tend to have cooler 60µm/25µm colors; this correlation was previously ascribed to the effect of obscuration towards the nuclear region. We find some evidence that Sy2s without polarized broad lines have larger absorbing column density (N H ) and that a fraction of them are characterized by dust lanes crossing their nuclei. However, we find that the IR colors do not correlate with N H , in disagreement with the obscuration scenario. Also, Sy2s without polarized broad lines follow the same radio-FIR relation as normal and starburst galaxies, at variance with Sy2s with polarized broad lines. These results indicate that the lack of broad lines in the polarized spectrum of Sy2s is mostly due to the contribution/dilution from the host galaxy or from a circumnuclear starburst, though at a lower extent the obscuration toward the nuclear region also plays a role.

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“…The latter are known to have relatively highly inclined tori (warm IR colors) in the Unified Model (e.g. Heisler et al 1997 and several important references therein). In any case the other bright Seyfert 2's have much larger columns with many Compton thick examples found (Maiolino et al 1998).…”

Section: Relationship Of Ultraluminous Iras Galaxies To Quasarsmentioning

confidence: 99%

Millimeter-wave spectroscopy and mapping of quasar hosts, and the status of ULIRGS as Quasar 2s

Antonucci

1999

Advances in Space Research

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It is becoming possible to detect high redshift quasars in various molecular lines, and to show by mapping lensed objects that the strong dust and molecular emission arises in warm dense ∼ 100 pc-scale "tori." The properties of ULIRGs, at least those with AGN-like narrow line regions, are very similar, as expected in the hidden quasar hypothesis. Several of the latter are in fact confirmed as "Quasar 2s" by spectropolarimetry. INTRODUCTION: DETECTIONS OF MOLECULES IN QUASAR HOSTS

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Visibility of scattered broad-line emission in Seyfert 2 galaxies

Cited by 145 publications

References 22 publications

Hidden Broad-Line Seyfert 2 Galaxies in the C[CLC]f[/CLC]A and 12 μ[CLC]m[/CLC] Samples

Hidden Broad-Line Seyfert 2 Galaxies in the C[CLC]f[/CLC]A and 12 μ[CLC]m[/CLC] Samples

Nuclear obscuration and scattering in Seyfert 2 galaxies

Millimeter-wave spectroscopy and mapping of quasar hosts, and the status of ULIRGS as Quasar 2s

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