TRGB Distances to Seyfert Galaxies NGC 1068, NGC 3227, NGC 4051, and NGC 4151

The 21-cm wavelength radiation from neutral hydrogen in NGC 1068, NGC 3227, NGC 4051 and NGC 4151 has been observed with the large radio telescope at Nanĉay, France. Since the angular sizes of these galaxies are of the same order as the telescope right ascension beam-width, no information on the angular distribution of the neutral hydrogen was obtained. However the radial velocity distribution of the total hydrogen (the ‘integrated profile’) of the whole galaxy was measured for each of the four galaxies. The hydrogen masses and total masses can be calculated from these profiles using simple models of galaxy shapes and rotation curves.Optical spectra sometimes show evidence for explosive phenomena and radial outflow of gas in the central regions of Seyfert galaxies. We have examined the integrated radio profiles for indications of large-scale radial motions of neutral hydrogen in two ways. First, for all four galaxies observed, we compare the ratios of hydrogen mass to total mass with the values obtained from other galaxies (not Seyfert) of the same morphological type. Second, for these galaxies where the optical data are available, we compare the estimates of total mass obtained from the optical spectra with the estimates based on the width of the radio profile.We conclude from these comparisons that the integrated profile of NGC 1068 is unusually broad. One possible interpretation which is qualitatively consistent with the optical data is that an appreciable fraction (about ⅓) of the neutral hydrogen content of NGC 1068 is moving radially outward with velocities of about 200 km s−1 An indication of similar phenomena (although less extreme) is obtained for NGC 4051. The widths of the integrated profiles of NGC 3227 and NGC 4151 do not seem unusual.

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A Study of the Seyfert Galaxy NGC 4151

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000010043 ◽

1967 ◽

Vol 1 (1) ◽

pp. 7-7 ◽

Cited By ~ 1

Author(s):

J. B. Oke ◽

Wallace L. W. Sargent

Keyword(s):

Continuous Spectrum ◽

Seyfert Galaxy ◽

Seyfert Galaxies ◽

Radio Galaxies ◽

Emission Lines ◽

Ngc 4151 ◽

Broad Emission ◽

Ngc 1068 ◽

Stellar Sources ◽

No Absorption

The small group of known Seyfert galaxies (Seyfert 1943) is of interest because it is clear that some violent activity is occurring in the nucleus, and some of the properties suggest a relationship with quasi-stellar sources. The spectrum of a Seyfert galaxy consists of strong, often very broad, emission lines superposed on a continuous spectrum which in some cases shows no absorption-line features. Two of the galaxies, NGC 1068 and 1275, are radio galaxies and the latter is known to be variable at radio frequencies (Dent 1966).

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Survey of Milliarcsec Structure in Eight Seyfert Galaxies: Results on NGC 1068 and NGC 4151

International Astronomical Union Colloquium ◽

10.1017/s0252921100045668 ◽

1998 ◽

Vol 164 ◽

pp. 301-302 ◽

Cited By ~ 3

Author(s):

A. L. Roy ◽

J. S. Ulvestad ◽

E. J. M. Colbert ◽

A. S. Wilson ◽

R. P. Norris

Keyword(s):

Spectral Index ◽

Low Frequency ◽

Seyfert Galaxies ◽

Scale Structure ◽

Scale Morphology ◽

Ngc 4151 ◽

Ngc 1068

AbstractWe are surveying eight nearby Seyfert galaxies (four Sy1s and four Sy2s) that have compact radio cores, using the VLBA. We are interested in parsec-scale morphology and low-frequency absorption effects, and so are observing four frequencies (1.6, 4.8, 8.4 and 15 GHz) to get spectral-index diagnostics. In this paper, we present results on two galaxies, NGC 1068 and NGC 4151. NGC 4151 shows a curved radio jet on the sub-parsec scale, with the smallest scale structure misaligned by 55° from the jet on scales of parsecs to hundreds of parsecs. NGC 1068 contains several components in the inner tens of parsecs, with those components showing a variety of absorption and resolution effects.

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Photoproduction of gravitational radiation by some astrophysical objects

Canadian Journal of Physics ◽

10.1139/p76-009 ◽

1976 ◽

Vol 54 (1) ◽

pp. 76-79 ◽

Cited By ~ 8

Author(s):

G. Papini ◽

S.-R. Valluri

Keyword(s):

Neutron Stars ◽

Electromagnetic Fields ◽

Gravitational Radiation ◽

Galactic Center ◽

Seyfert Galaxies ◽

The Sun ◽

Ngc 4151 ◽

Astrophysical Objects ◽

Ngc 1068

Estimates are given for the amounts of gravitational radiation produced in the interaction of photons with the static electromagnetic fields of some astrophysical objects. These are the Sun, Quasar 3C273, Seyfert galaxies NGC 1068 and NGC 4151, the Galactic Center, and neutron stars.

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Velocity Offsets Due to Mass Outflows in Active Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310006769 ◽

2009 ◽

Vol 5 (S267) ◽

pp. 387-392

Author(s):

D. M. Crenshaw ◽

S. B. Kraemer ◽

H. R. Schmitt ◽

R. F. Mushotzky ◽

J. P. Dunn

Keyword(s):

Seyfert Galaxies ◽

Emission Lines ◽

Host Galaxy ◽

Host Galaxies ◽

Ionized Gas ◽

Ngc 4151 ◽

Spatially Resolved ◽

Mass Outflow ◽

Ngc 1068 ◽

Narrow Emission

AbstractWe present a study of the radial velocity offsets between AGN-related narrow emission lines and host-galaxy emission and absorption lines in Seyfert galaxies with observed redshifts less than 0.043. We find that 35% of the Seyferts in the sample show [O iii] emission lines with blueshifts with respect to their host galaxies exceeding 50 km s−1, whereas only 6% show redshifts this large, in qualitative agreement with most previous studies. We also find that a greater percentage of Seyfert 1 galaxies show blueshifts than Seyfert 2 galaxies. Using HST/STIS spatially-resolved spectra of the Seyfert 2 galaxy NGC 1068 and the Seyfert 1 galaxy NGC 4151, we generate geometric models of their narrow-line regions (NLRs) and inner galactic disks and show how these models can explain the blueshifted [O iii] emission lines in collapsed STIS spectra of these two Seyferts. We conclude that the combination of mass outflow of ionized gas in the NLR and extinction by dust in the inner disk (primarily in the form of dust spirals) is primarily responsible for the velocity offsets in Seyfert galaxies.

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Radio structures of Seyfert galaxies. IV - Jets in NGC 1068 and NGC 4151

The Astrophysical Journal ◽

10.1086/160529 ◽

1982 ◽

Vol 263 ◽

pp. 576 ◽

Cited By ~ 72

Author(s):

A. S. Wilson ◽

J. S. Ulvestad

Keyword(s):

Seyfert Galaxies ◽

Ngc 4151 ◽

Ngc 1068

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Exploring the Inner Narrow-Line Regions of Seyfert Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s174392131000685x ◽

2009 ◽

Vol 5 (S267) ◽

pp. 401-401

Author(s):

S. B. Kraemer ◽

D. M. Crenshaw ◽

M. L. Trippe ◽

H. R. Schmitt ◽

M. Meléndez

Keyword(s):

Emission Line ◽

Seyfert Galaxies ◽

Uv Spectra ◽

Narrow Line ◽

Ngc 4151 ◽

Radial Extent ◽

Wide Range ◽

Heterogeneous Nature ◽

Mass Outflow ◽

Ngc 1068

In HST/STIS optical spectra of Seyfert galaxies, there is often a bright knot of [O iii] emission in the inner NLR. In the case of the Seyfert 1 galaxy NGC 4151, we have shown that the emission-line gas may be associated with the mass outflow detected in absorption in UV spectra, which suggests that we are probing regions close to the AGN. Here we present results for the luminous Seyfert 2 galaxy Mrk 573. The spectra reveal the presence of lines from a wide range of ionization states (see Figure 1), which is indicative of the heterogeneous nature of the emission-line gas. As in our studies of other Seyfert galaxies, including NGC 1068, NGC 4151, and Mrk 3, there is evidence for emission from low-ionization gas outside the nominal emission-line bicone. Finally, based on photoionization modeling, we find that the central emission-line knot in Mrk 573 is some tens of parsecs from the AGN, similar to other Seyfert 2 galaxies, which suggests that the material that is obscuring the central AGN in Seyfert 2s must have a similar radial extent.

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Activity in the Nuclei of Seyfert Galaxies in the Visual and Infrared

Symposium - International Astronomical Union ◽

10.1017/s0074180900005489 ◽

1972 ◽

Vol 44 ◽

pp. 165-170

Author(s):

A. G. Pacholczyk

Keyword(s):

Flux Density ◽

Time Scale ◽

Seyfert Galaxies ◽

Ngc 4151 ◽

Ngc 1068

This paper reports (1) a possible 5.1 yr period in the optical variations of the nucleus of NGC 4151; and (2) variations with a time-scale of a few days in the 2.2 micron flux density of NGC 1068, implying that the size of the infrared emitting region is not larger than a few times 1015 cm.

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