Free-free absorption in the Seyfert nucleus of NGC 4151

A. Pedlar; B. Fernandez; N. G. Hamilton; M. P. Redman; P. E. Dewdney

doi:10.1046/j.1365-8711.1998.01985.x

Free-free absorption in the Seyfert nucleus of NGC 4151

A. Pedlar
, B. Fernandez
, N. G. Hamilton
, M. P. Redman
, P. E. Dewdney

Research output: Contribution to a Journal (Peer & Non Peer) › Article › peer-review

20 Citations (Scopus)

Abstract

We present subarcsecond MERLIN 0.4-GHz (73 cm) and 1.6-GHz (18 cm) radio measurements of the nuclear region of the Seyfert galaxy NGC 4151. By comparison with higher frequency observations, we deduce that one component (C4) shows a low-frequency turnover which we interpret as evidence for free-free absorption by ionized gas with an emission measure between 3 × 10⁵ and 10⁶ pc cm^-6. The free-free absorption appears to be localized to a region ∼50 pc in extent, and we consider models in which the ionized gas may be closely associated with a neutral molecular torus.

Original language	English
Pages (from-to)	1071-1076
Number of pages	6
Journal	Monthly Notices of the Royal Astronomical Society
Volume	300
Issue number	4
DOIs	https://doi.org/10.1046/j.1365-8711.1998.01985.x
Publication status	Published - 11 Nov 1998
Externally published	Yes

Keywords

Galaxies: Seyfert
Galaxies: individual: NGC 4151
Galaxies: nuclei
Radio continuum: galaxies

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10.1046/j.1365-8711.1998.01985.x

Cite this

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title = "Free-free absorption in the Seyfert nucleus of NGC 4151",

abstract = "We present subarcsecond MERLIN 0.4-GHz (73 cm) and 1.6-GHz (18 cm) radio measurements of the nuclear region of the Seyfert galaxy NGC 4151. By comparison with higher frequency observations, we deduce that one component (C4) shows a low-frequency turnover which we interpret as evidence for free-free absorption by ionized gas with an emission measure between 3 × 105 and 106 pc cm-6. The free-free absorption appears to be localized to a region ∼50 pc in extent, and we consider models in which the ionized gas may be closely associated with a neutral molecular torus.",

keywords = "Galaxies: Seyfert, Galaxies: individual: NGC 4151, Galaxies: nuclei, Radio continuum: galaxies",

author = "A. Pedlar and B. Fernandez and Hamilton, \{N. G.\} and Redman, \{M. P.\} and Dewdney, \{P. E.\}",

year = "1998",

month = nov,

day = "11",

doi = "10.1046/j.1365-8711.1998.01985.x",

language = "English",

volume = "300",

pages = "1071--1076",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press",

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}

TY - JOUR

T1 - Free-free absorption in the Seyfert nucleus of NGC 4151

AU - Pedlar, A.

AU - Fernandez, B.

AU - Hamilton, N. G.

AU - Redman, M. P.

AU - Dewdney, P. E.

PY - 1998/11/11

Y1 - 1998/11/11

N2 - We present subarcsecond MERLIN 0.4-GHz (73 cm) and 1.6-GHz (18 cm) radio measurements of the nuclear region of the Seyfert galaxy NGC 4151. By comparison with higher frequency observations, we deduce that one component (C4) shows a low-frequency turnover which we interpret as evidence for free-free absorption by ionized gas with an emission measure between 3 × 105 and 106 pc cm-6. The free-free absorption appears to be localized to a region ∼50 pc in extent, and we consider models in which the ionized gas may be closely associated with a neutral molecular torus.

AB - We present subarcsecond MERLIN 0.4-GHz (73 cm) and 1.6-GHz (18 cm) radio measurements of the nuclear region of the Seyfert galaxy NGC 4151. By comparison with higher frequency observations, we deduce that one component (C4) shows a low-frequency turnover which we interpret as evidence for free-free absorption by ionized gas with an emission measure between 3 × 105 and 106 pc cm-6. The free-free absorption appears to be localized to a region ∼50 pc in extent, and we consider models in which the ionized gas may be closely associated with a neutral molecular torus.

KW - Galaxies: Seyfert

KW - Galaxies: individual: NGC 4151

KW - Galaxies: nuclei

KW - Radio continuum: galaxies

UR - https://www.scopus.com/pages/publications/0008543786

U2 - 10.1046/j.1365-8711.1998.01985.x

DO - 10.1046/j.1365-8711.1998.01985.x

M3 - Article

SN - 0035-8711

VL - 300

SP - 1071

EP - 1076

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 4

ER -

Free-free absorption in the Seyfert nucleus of NGC 4151

Abstract

Keywords

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