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Title: Dust in the nuclei of the Seyfert galaxies Markarian 231 and NGC 4151

Abstract

Observations carried out with a 8-13 micron grating-spectrometer of Mrk 231 and NGC 4151 are reported. The Mrk 231 data can be fitted to various thermal dust emission models or a single power law, with dust extinction. In all the model fits, except for that of graphite and silicon carbide grain emission, a component of silicate absorption of optical depth of not more than 0.7 is required. Confirming published work, the absorption being at the redshift of the low-redshift absorption-line system is ruled out. The high values of silicate optical depth absorption do not give ratios to the galaxy's visual extinction which are comparable to those of galactic H II regions. Weak evidence for a 10-micron absorption feature in NGC 4151 is also reported. This is somewhat contrary to expectation, since the visual extinction of NGC 4151 is lower than that of Mrk 231, and since there is evidence to support a nonthermal rather than thermal dust origin for the infrared continuum emission. 46 references.

Authors:
; ; ;
Publication Date:
Research Org.:
Hawaii Univ., Mauna Kea
OSTI Identifier:
6094894
Resource Type:
Journal Article
Resource Relation:
Journal Name: Publ. Astron. Soc. Pac.; (United States); Journal Volume: 96
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; SEYFERT GALAXIES; COSMIC DUST; GALAXY NUCLEI; ABSORPTION; INTERSTELLAR SPACE; DUSTS; GALAXIES; SPACE; 640105* - Astrophysics & Cosmology- Galaxies

Citation Formats

Jones, B., Worrall, D.M., Rodriguez-Espinosa, J.M., and Stein, W.A. Dust in the nuclei of the Seyfert galaxies Markarian 231 and NGC 4151. United States: N. p., 1984. Web. doi:10.1086/131407.
Jones, B., Worrall, D.M., Rodriguez-Espinosa, J.M., & Stein, W.A. Dust in the nuclei of the Seyfert galaxies Markarian 231 and NGC 4151. United States. doi:10.1086/131407.
Jones, B., Worrall, D.M., Rodriguez-Espinosa, J.M., and Stein, W.A. Sat . "Dust in the nuclei of the Seyfert galaxies Markarian 231 and NGC 4151". United States. doi:10.1086/131407.
@article{osti_6094894,
title = {Dust in the nuclei of the Seyfert galaxies Markarian 231 and NGC 4151},
author = {Jones, B. and Worrall, D.M. and Rodriguez-Espinosa, J.M. and Stein, W.A.},
abstractNote = {Observations carried out with a 8-13 micron grating-spectrometer of Mrk 231 and NGC 4151 are reported. The Mrk 231 data can be fitted to various thermal dust emission models or a single power law, with dust extinction. In all the model fits, except for that of graphite and silicon carbide grain emission, a component of silicate absorption of optical depth of not more than 0.7 is required. Confirming published work, the absorption being at the redshift of the low-redshift absorption-line system is ruled out. The high values of silicate optical depth absorption do not give ratios to the galaxy's visual extinction which are comparable to those of galactic H II regions. Weak evidence for a 10-micron absorption feature in NGC 4151 is also reported. This is somewhat contrary to expectation, since the visual extinction of NGC 4151 is lower than that of Mrk 231, and since there is evidence to support a nonthermal rather than thermal dust origin for the infrared continuum emission. 46 references.},
doi = {10.1086/131407},
journal = {Publ. Astron. Soc. Pac.; (United States)},
number = ,
volume = 96,
place = {United States},
year = {Sat Sep 01 00:00:00 EDT 1984},
month = {Sat Sep 01 00:00:00 EDT 1984}
}
  • This paper presents and discusses new radio maps of the Seyfert galaxies NGC 1068 (at 1.4 and 15 GHz) and NGC 4151 (at 15 GHz) from the Very Large Array. The radio emission of NGC 1068 comprises a central component coincident with the optical nucleus and of size 0''.7 x 0''.3 in p.a. 28/sup 0/, a linear structure of extent 13'' in p.a. 33/sup 0/, and large scale emission of size at least 2'. The size and shape of the central component are very similar to those of the resolved optical nucleus, and the linear radio structure is probably relatedmore » to optical ''flares'' and ''prominences'' which extend from the nucleus in the same direction. Linear polarization of magnitude 13% is detected at 15 GHz in the NE lobe of the linear structure. If Faraday rotation is small, the magnetic field is aligned along the radio source axis. Earlier radio maps of NGC 4151 show a highly elongated source of extent approx.3''.5 in p.a. 77/sup 0/. In the center of this structure is found a double source of separation 0''.45 in p.a. 83/sup 0/. The present observations resolve each component of this double and indicate that the more intense component has a flatter spectrum and is probably associated with the nucleus proper.« less
  • We report mid-infrared interferometric measurements (based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, programme number 081.B-0092(A)) with approx10 mas resolution, which resolve the warm (T = 285{sup +25} {sub -50} K) thermal emission at the center of NGC 4151. Using pairs of Very Large Telescope 8.2 m telescopes with the Mid-infrared interferometric instrument and by comparing the data to a Gaussian model, we determined the diameter of the dust emission region, albeit only along one position angle, to be (2.0 +- 0.4) pc (FWHM). This is the first size and temperature estimatemore » for the nuclear warm dust distribution in a Seyfert 1 galaxy. The parameters found are comparable to those in Seyfert 2 galaxies, thus providing direct support for the unified model. Using simple analytic temperature distributions, we find that the mid-infrared emission is probably not the smooth continuation of the hot nuclear source that is marginally resolved with K-band interferometry. We also detected weak excess emission around 10.5 mum in our shorter baseline observation, possibly indicating that silicate emission is extended to the parsec scale.« less
  • Near-IR CCD moderate-resolution spectra in the 7000-11,000 wavelength range were obtained for NGC 1976 and NGC 4151 in three overlapping segments. The strongest three lines in both objects are forbidden S III 9531, He I 10830, and forbidden S III 9069. Also, lower resolution spectra of 14 additional Seyfert galaxies were obtained. In all but two of these spectra, the strongest line is forbidden S III 9531. The line strengths among these galaxies are compared to trace ionization behavior. 59 refs.