Unabsorbed Seyfert 2 galaxies: The case of "naked" AGN

F. Panessa, F. J. Carrera, S. Bianchi, A. Corral, F. Gastaldello, X. Barcons, L. Bassani, G. Matt, L. Monaco

Resultado de la investigación: Conference contribution

Resumen

A class of "naked" AGN has been reported (Hawkins 2004), characterized by strong amplitude optical brightness variability and the complete absence of broad emission lines in the optical spectrum. The optical variability suggests that the nucleus is seen directly, while the absence of broad lines contradicts the simple formulation of Unified Models for AGN. We observed quasi simultaneously in X-rays (XMM-Newton) and optical (NTT, La Silla) two "naked" AGN, confirming the "naked" nature of Q2131-427 for which no broad emission line components have been detected in the optical spectrum and its X-ray spectrum shows no signs of intrinsic absorption. The optical and X-ray mismatch in this source cannot be ascribed to a high nuclear dust-to-gas ratio and a Compton Thick nature is ruled out. We suggest that the Broad Line Region (BLR) may be completely absent in this source, possibly as a consequence of its low Eddington ratio. The second "naked" AGN candidate, Q2130-431, shows Hα and Hβ broad emission line components in its optical spectrum, revealing the presence of a BLR. A mild X-ray absorption is expected in intermediate type 1.8 Seyfert galaxies like Q2130-431, however we put a very low upper limit on the column density, also the low Balmer decrement suggests that the BLR itself does not suffer from reddening. We propose that in this object the BLR is instrinsecally weak, making a case of "true" intermediate Seyfert galaxy.

Idioma originalEnglish
Título de la publicación alojadaX-ray Astronomy-2009
Subtítulo de la publicación alojadaPresent Status, Multi-Wavelength Approach and Future Perspectives - Proceedings of the International Conference
Páginas489-490
Número de páginas2
Volumen1248
DOI
EstadoPublished - 26 ago 2010
EventoInternational Conference on X-ray Astronomy-2009: Present Status, Multi-Wavelength Approach and Future Perspectives - Bologna, Italy
Duración: 7 sep 200911 sep 2009

Other

OtherInternational Conference on X-ray Astronomy-2009: Present Status, Multi-Wavelength Approach and Future Perspectives
PaísItaly
CiudadBologna
Período7/09/0911/09/09

Huella dactilar

galaxies
optical spectrum
Seyfert galaxies
x rays
XMM-Newton telescope
newton
brightness
dust
formulations
nuclei
gases

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Citar esto

Panessa, F., Carrera, F. J., Bianchi, S., Corral, A., Gastaldello, F., Barcons, X., ... Monaco, L. (2010). Unabsorbed Seyfert 2 galaxies: The case of "naked" AGN. En X-ray Astronomy-2009: Present Status, Multi-Wavelength Approach and Future Perspectives - Proceedings of the International Conference (Vol. 1248, pp. 489-490) https://doi.org/10.1063/1.3475314
Panessa, F. ; Carrera, F. J. ; Bianchi, S. ; Corral, A. ; Gastaldello, F. ; Barcons, X. ; Bassani, L. ; Matt, G. ; Monaco, L. / Unabsorbed Seyfert 2 galaxies : The case of "naked" AGN. X-ray Astronomy-2009: Present Status, Multi-Wavelength Approach and Future Perspectives - Proceedings of the International Conference. Vol. 1248 2010. pp. 489-490
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abstract = "A class of {"}naked{"} AGN has been reported (Hawkins 2004), characterized by strong amplitude optical brightness variability and the complete absence of broad emission lines in the optical spectrum. The optical variability suggests that the nucleus is seen directly, while the absence of broad lines contradicts the simple formulation of Unified Models for AGN. We observed quasi simultaneously in X-rays (XMM-Newton) and optical (NTT, La Silla) two {"}naked{"} AGN, confirming the {"}naked{"} nature of Q2131-427 for which no broad emission line components have been detected in the optical spectrum and its X-ray spectrum shows no signs of intrinsic absorption. The optical and X-ray mismatch in this source cannot be ascribed to a high nuclear dust-to-gas ratio and a Compton Thick nature is ruled out. We suggest that the Broad Line Region (BLR) may be completely absent in this source, possibly as a consequence of its low Eddington ratio. The second {"}naked{"} AGN candidate, Q2130-431, shows Hα and Hβ broad emission line components in its optical spectrum, revealing the presence of a BLR. A mild X-ray absorption is expected in intermediate type 1.8 Seyfert galaxies like Q2130-431, however we put a very low upper limit on the column density, also the low Balmer decrement suggests that the BLR itself does not suffer from reddening. We propose that in this object the BLR is instrinsecally weak, making a case of {"}true{"} intermediate Seyfert galaxy.",
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Panessa, F, Carrera, FJ, Bianchi, S, Corral, A, Gastaldello, F, Barcons, X, Bassani, L, Matt, G & Monaco, L 2010, Unabsorbed Seyfert 2 galaxies: The case of "naked" AGN. En X-ray Astronomy-2009: Present Status, Multi-Wavelength Approach and Future Perspectives - Proceedings of the International Conference. vol. 1248, pp. 489-490, International Conference on X-ray Astronomy-2009: Present Status, Multi-Wavelength Approach and Future Perspectives, Bologna, Italy, 7/09/09. https://doi.org/10.1063/1.3475314

Unabsorbed Seyfert 2 galaxies : The case of "naked" AGN. / Panessa, F.; Carrera, F. J.; Bianchi, S.; Corral, A.; Gastaldello, F.; Barcons, X.; Bassani, L.; Matt, G.; Monaco, L.

X-ray Astronomy-2009: Present Status, Multi-Wavelength Approach and Future Perspectives - Proceedings of the International Conference. Vol. 1248 2010. p. 489-490.

Resultado de la investigación: Conference contribution

TY - GEN

T1 - Unabsorbed Seyfert 2 galaxies

T2 - The case of "naked" AGN

AU - Panessa, F.

AU - Carrera, F. J.

AU - Bianchi, S.

AU - Corral, A.

AU - Gastaldello, F.

AU - Barcons, X.

AU - Bassani, L.

AU - Matt, G.

AU - Monaco, L.

PY - 2010/8/26

Y1 - 2010/8/26

N2 - A class of "naked" AGN has been reported (Hawkins 2004), characterized by strong amplitude optical brightness variability and the complete absence of broad emission lines in the optical spectrum. The optical variability suggests that the nucleus is seen directly, while the absence of broad lines contradicts the simple formulation of Unified Models for AGN. We observed quasi simultaneously in X-rays (XMM-Newton) and optical (NTT, La Silla) two "naked" AGN, confirming the "naked" nature of Q2131-427 for which no broad emission line components have been detected in the optical spectrum and its X-ray spectrum shows no signs of intrinsic absorption. The optical and X-ray mismatch in this source cannot be ascribed to a high nuclear dust-to-gas ratio and a Compton Thick nature is ruled out. We suggest that the Broad Line Region (BLR) may be completely absent in this source, possibly as a consequence of its low Eddington ratio. The second "naked" AGN candidate, Q2130-431, shows Hα and Hβ broad emission line components in its optical spectrum, revealing the presence of a BLR. A mild X-ray absorption is expected in intermediate type 1.8 Seyfert galaxies like Q2130-431, however we put a very low upper limit on the column density, also the low Balmer decrement suggests that the BLR itself does not suffer from reddening. We propose that in this object the BLR is instrinsecally weak, making a case of "true" intermediate Seyfert galaxy.

AB - A class of "naked" AGN has been reported (Hawkins 2004), characterized by strong amplitude optical brightness variability and the complete absence of broad emission lines in the optical spectrum. The optical variability suggests that the nucleus is seen directly, while the absence of broad lines contradicts the simple formulation of Unified Models for AGN. We observed quasi simultaneously in X-rays (XMM-Newton) and optical (NTT, La Silla) two "naked" AGN, confirming the "naked" nature of Q2131-427 for which no broad emission line components have been detected in the optical spectrum and its X-ray spectrum shows no signs of intrinsic absorption. The optical and X-ray mismatch in this source cannot be ascribed to a high nuclear dust-to-gas ratio and a Compton Thick nature is ruled out. We suggest that the Broad Line Region (BLR) may be completely absent in this source, possibly as a consequence of its low Eddington ratio. The second "naked" AGN candidate, Q2130-431, shows Hα and Hβ broad emission line components in its optical spectrum, revealing the presence of a BLR. A mild X-ray absorption is expected in intermediate type 1.8 Seyfert galaxies like Q2130-431, however we put a very low upper limit on the column density, also the low Balmer decrement suggests that the BLR itself does not suffer from reddening. We propose that in this object the BLR is instrinsecally weak, making a case of "true" intermediate Seyfert galaxy.

KW - Active Nuclei

KW - Seyfert galaxies

KW - X-rays

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U2 - 10.1063/1.3475314

DO - 10.1063/1.3475314

M3 - Conference contribution

AN - SCOPUS:77955801929

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BT - X-ray Astronomy-2009

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Panessa F, Carrera FJ, Bianchi S, Corral A, Gastaldello F, Barcons X y otros. Unabsorbed Seyfert 2 galaxies: The case of "naked" AGN. En X-ray Astronomy-2009: Present Status, Multi-Wavelength Approach and Future Perspectives - Proceedings of the International Conference. Vol. 1248. 2010. p. 489-490 https://doi.org/10.1063/1.3475314