Emission line intensities as functions of the color index for type 1 Seyfert galaxies

Abstract Using data from SDSS, UKIDSS and WISE, we investigate the properties of the high-frequency cutoff to the infrared emission in ≃5000 carefully selected luminous (Lbol ∼ 1047) type 1 quasars. The strength of ≃2 μm emission, corresponding to emission from the hottest ($T>1200\rm \, K$) dust in the sublimation zone surrounding the central continuum source, is observed to correlate with the blueshift of the C iv λ1550 emission line. We therefore find that objects with stronger signatures of nuclear outflows tend to have a larger covering fraction of sublimation-temperature dust. When controlling for the observed outflow strength, the hot dust covering fraction does not vary significantly across our sample as a function of luminosity, black hole mass or Eddington fraction. The correlation between the hot dust and the C iv line blueshifts, together with the lack of correlation between the hot dust and other parameters, therefore provides evidence of a link between the properties of the broad emission line region and the infrared-emitting dusty regions in quasars.

Download Full-text

Spitzer IRS Observations of Low-Mass Seyfert Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310006459 ◽

2009 ◽

Vol 5 (S267) ◽

pp. 268-268

Author(s):

Carol E. Thornton ◽

Aaron J. Barth ◽

Luis C. Ho ◽

Jenny E. Greene

Keyword(s):

Dust Emission ◽

Seyfert Galaxies ◽

Sloan Digital Sky Survey ◽

Physical Conditions ◽

Sky Survey ◽

Low Mass ◽

Ngc 4395 ◽

Black Hole Masses

The Sloan Digital Sky Survey has made it possible to identify the first samples of active galaxies with estimated black hole masses below ~ 106M⊙. We have obtained Spitzer IRS low-resolution spectra, covering 5–38 μm, of a sample of 41 Seyfert galaxies with low-mass black holes. Our sample includes SDSS-selected objects from the low-mass Seyfert 1 sample of Greene & Ho (2004) and the low-mass Seyfert 2 sample of Barth et al. (2008), as well as NGC 4395 and POX 52. The goals of this work are to examine the dust emission properties of these objects and investigate the relationship between type 1 and type 2 AGNs at low luminosities and low masses, to search for evidence of star formation, and to use emission-line diagnostics to constrain physical conditions within the narrow-line regions. Here we present preliminary results from this project.

Download Full-text

The Excitation Mechanism of Emission‐Line Regions in Seyfert Galaxies

The Astrophysical Journal ◽

10.1086/307570 ◽

1999 ◽

Vol 521 (2) ◽

pp. 531-546 ◽

Cited By ~ 25

Author(s):

Ian Evans ◽

Anuradha Koratkar ◽

Mark Allen ◽

Michael Dopita ◽

Zlatan Tsvetanov

Keyword(s):

Emission Line ◽

Seyfert Galaxies ◽

Excitation Mechanism

Download Full-text

CO in Seyfert Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900141348 ◽

1989 ◽

Vol 134 ◽

pp. 359-364

Author(s):

Timothy M. Heckman

Keyword(s):

Seyfert Galaxies ◽

Normal Galaxies ◽

Line Widths ◽

Co Emission

We present data for Seyfert and normal galaxies in the Revised Shapley-Ames Catalog. The type 2 Seyferts are stronger CO and Far-IR emitters (by factors of 2–4) than either normal galaxies or type 1 Seyferts. The Seyfert CO line-widths correlate with both the 21cm HI and [OIII]5007 line-widths. Interferometer maps show that in many Seyferts the CO emission is strongly concentrated within radii of 100–1000pc of the nucleus. The implications of these results are briefly discussed.

Download Full-text

IUE Spectra of The by Dra/Flare Star AU Mic

International Astronomical Union Colloquium ◽

10.1017/s0252921100096172 ◽

1983 ◽

Vol 71 ◽

pp. 249-250

Author(s):

C.J. Butler ◽

A.D. Andrews ◽

J.G. Doyle ◽

P.B. Byrne ◽

J.L. Linsky ◽

...

Keyword(s):

Light Curve ◽

Emission Line ◽

Flare Star ◽

Emission Lines ◽

Spectral Variation ◽

Strong Emission ◽

Line Intensities ◽

The Mean ◽

Phase Interval

A coordinated series of ground-based optical and IUE observations of BY Dra variables was undertaken to follow the spectral variation of these stars over one cycle. In the first series 20 LWR and 19 SWP trailed spectra were taken of AU Mic over a three day period 4-6 August 1980 .In Figure 1 we show the mean integrated fluxes for the strong emission lines in the SWP spectra of AU Mic over the observed phase interval of 0.14 to 0.8 together with an approximate V light curve determined by the FES on IUE. From comparison of the emission line intensities and FES magnitudes in Figure 1 several points emerge.

Download Full-text

Dust Distribution in IRAS Seyfert Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900175539 ◽

1994 ◽

Vol 159 ◽

pp. 355-355

Author(s):

M. G. Pastoriza ◽

Charles Bonatto ◽

Eduardo Bica ◽

T. Storchi-Bergmann

Keyword(s):

Emission Line ◽

Power Law ◽

Dust Emission ◽

Seyfert Galaxies ◽

Emission Model ◽

Line Region ◽

Population Type ◽

The Galaxy ◽

Dilution Effects ◽

Dust Distribution

Observational evidences of dust in the nuclear region of AGNs are substantial (Rudy 1984, ApJ, 284, 33; Jones et al. 1984, PASP, 96, 692). The ionization cones observed in several Seyfert galaxies has been interpreted as shadowing effects by a dust obscuring torus which hides the broad emission line region (BLR) and the central source (Wilson 1992; Storchi-Bergmann, Mulchaey and Wilson 1992, ApJ 395, L73). A large sample of optical and far-IR data for IRAS Seyfert galaxies has been analysed together with dust emission models (Bonatto and Pastoriza 1993), where it has been concluded that the same dust emission model can be applied to both Seyfert types. In order to further study the effects of dust in the spectra of active galactic nuclei, we have obtained spectrophotometry of 21 IRAS Seyfert galaxies in the range 3500–7200 Å and analyse them in conjuction with their IRAS fluxes. The stellar population type is derived from comparisons with normal galaxy templates using dilution effects in the K CaII line as discriminator. For 55% of the sample the population is of late type. For the rest, blue continua due to recent star formation and/or power-law may amount up to 30% at 4000Å. We conclude that the bulge stellar populations of IRAS Seyfert galaxies are similar to those of normal spirals, except that they are more reddened by E(B-V)i ∼ 0.20. Population-subtracted emission line ratios indicate on average stronger reddening for the narrow-line region (E(B-V)l ∼ 0.8. From photoionization models a power-law index for the ionizing continuum α=1.5, and a metallicity larger than solar are obtained. The most luminous IRAS galaxy of the sample (IRAS555) is discuss in detail: in order to be compatible with the observed IRAS fluxes and the optical stellar continuum, the ionizing continuum must be reddened by AV > 10 magnitudes. Consequently a dust structure in this galaxy appears to be increasingly affecting stars and gas towards the galaxy center.

Download Full-text