Variability of Fe II Emission Features in the Seyfert 1 Galaxy NGC 5548

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Variability of Fe II Emission Features in the Seyfert 1 Galaxy NGC 5548. / Vestergaard, Marianne; Peterson, B. M.

In: Astrophysical Journal, Vol. 625, No. 2, 688, 21.02.2005.

Research output: Contribution to journal › Journal article › Research › peer-review

Harvard

Vestergaard, M & Peterson, BM 2005, 'Variability of Fe II Emission Features in the Seyfert 1 Galaxy NGC 5548', Astrophysical Journal, vol. 625, no. 2, 688. https://doi.org/10.1086/429791

APA

Vestergaard, M., & Peterson, B. M. (2005). Variability of Fe II Emission Features in the Seyfert 1 Galaxy NGC 5548. Astrophysical Journal, 625(2), [688]. https://doi.org/10.1086/429791

Vancouver

Vestergaard M, Peterson BM. Variability of Fe II Emission Features in the Seyfert 1 Galaxy NGC 5548. Astrophysical Journal. 2005 Feb 21;625(2). 688. https://doi.org/10.1086/429791

Author

Vestergaard, Marianne ; Peterson, B. M. / Variability of Fe II Emission Features in the Seyfert 1 Galaxy NGC 5548. In: Astrophysical Journal. 2005 ; Vol. 625, No. 2.

Bibtex

@article{20a1958223024d409f133a7f62fdc7a7,
title = "Variability of Fe II Emission Features in the Seyfert 1 Galaxy NGC 5548",
abstract = "We study the low-contrast Fe II emission blends in the ultraviolet (1250--2200A) and optical (4000--6000A) spectra of the Seyfert 1 galaxy NGC 5548 and show that these features vary in flux and that these variations are correlated with those of the optical continuum. The amplitude of variability of the optical Fe II emission is 50% - 75% that of Hbeta and the ultraviolet Fe II emission varies with an even larger amplitude than Hbeta. However, accurate measurement of the flux in these blends proves to be very difficult even using excellent Fe II templates to fit the spectra. We are able to constrain only weakly the optical Fe II emission-line response timescale to a value less than several weeks; this upper limit exceeds all the reliably measured emission-line lags in this source so it is not particularly meaningful. Nevertheless, the fact that the optical Fe II and continuum flux variations are correlated indicates that line fluorescence in a photoionized plasma, rather than collisional excitation, is responsible for the Fe II emission. The iron emission templates are available upon request.",
keywords = "astro-ph",
author = "Marianne Vestergaard and Peterson, {B. M.}",
year = "2005",
month = feb,
day = "21",
doi = "10.1086/429791",
language = "English",
volume = "625",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "Institute of Physics Publishing, Inc",
number = "2",

}

RIS

TY - JOUR

T1 - Variability of Fe II Emission Features in the Seyfert 1 Galaxy NGC 5548

AU - Vestergaard, Marianne

AU - Peterson, B. M.

PY - 2005/2/21

Y1 - 2005/2/21

N2 - We study the low-contrast Fe II emission blends in the ultraviolet (1250--2200A) and optical (4000--6000A) spectra of the Seyfert 1 galaxy NGC 5548 and show that these features vary in flux and that these variations are correlated with those of the optical continuum. The amplitude of variability of the optical Fe II emission is 50% - 75% that of Hbeta and the ultraviolet Fe II emission varies with an even larger amplitude than Hbeta. However, accurate measurement of the flux in these blends proves to be very difficult even using excellent Fe II templates to fit the spectra. We are able to constrain only weakly the optical Fe II emission-line response timescale to a value less than several weeks; this upper limit exceeds all the reliably measured emission-line lags in this source so it is not particularly meaningful. Nevertheless, the fact that the optical Fe II and continuum flux variations are correlated indicates that line fluorescence in a photoionized plasma, rather than collisional excitation, is responsible for the Fe II emission. The iron emission templates are available upon request.

AB - We study the low-contrast Fe II emission blends in the ultraviolet (1250--2200A) and optical (4000--6000A) spectra of the Seyfert 1 galaxy NGC 5548 and show that these features vary in flux and that these variations are correlated with those of the optical continuum. The amplitude of variability of the optical Fe II emission is 50% - 75% that of Hbeta and the ultraviolet Fe II emission varies with an even larger amplitude than Hbeta. However, accurate measurement of the flux in these blends proves to be very difficult even using excellent Fe II templates to fit the spectra. We are able to constrain only weakly the optical Fe II emission-line response timescale to a value less than several weeks; this upper limit exceeds all the reliably measured emission-line lags in this source so it is not particularly meaningful. Nevertheless, the fact that the optical Fe II and continuum flux variations are correlated indicates that line fluorescence in a photoionized plasma, rather than collisional excitation, is responsible for the Fe II emission. The iron emission templates are available upon request.

KW - astro-ph

U2 - 10.1086/429791

DO - 10.1086/429791

M3 - Journal article

VL - 625

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

M1 - 688

ER -

ID: 123369246