An Optical and H [CSC]i[/CSC] Study of NGC 5850: Victim of a High-Speed Encounter?

Higdon, James L.; Buta, Ronald J.; Purcell, Guy B.

doi:10.1086/300193

Cited by 36 publications

(41 citation statements)

References 41 publications

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“…In addition, if we, nevertheless, assume the gas motions to take place in the galactic plane, then it will turn out that they correspond to a radial outflow from the nucleus 1 with velocities 50 − 70 km s −1 . Such features are characteristic of Seyfert galaxies, but the optical spectrum of the galaxy contains no emission lines indicative of an active nucleus, nor are staburst observed here (Higdon et al, 1998). A more reasonable assumption is that the gas moves at r < 6 − 7 in a plane polar to the galactic disk.…”

Section: Velocity Fieldsmentioning

confidence: 72%

Two-dimensional spectroscopy of double-barred galaxies

Моисеев

2002

Astron. Lett.

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Abstract. We describe the results of our spectroscopy for a sample of barred galaxies whose inner regions exhibit an isophotal twist commonly called a secondary bar. The line-of-sight velocity fields of the ionized gas and stars and the light-of-sight velocity dispersion fields of the stars were constructed from two-dimensional spectroscopy with the 6m Special Astrophysical Observatory telescope. We detected various types of non-circular motions of ionized gas: radial flows within large-scale bars, counter-rotation of the gas and stars at the center of NGC 3945, a polar gaseous disk in NGC 5850, etc. Our analysis of the optical and near-infrared images (both ground-based and those from the Hubble Space Telescope) revealed circumnuclear minispirals in five objects. The presence of an inner (secondary) bar in the galaxy images is shown to have no effect on the circumnuclear kinematics of the gas and stars. Thus, contrary to popular belief, the secondary bar is not a dynamically decoupled galactic structure. We conclude that the so-called double-barred galaxies are not a separate type of galaxies but are a combination of objects with distinctly different morphology of their circumnuclear regions. (c) 2002 MAIK Nauka/Interperiodica.

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Section: Velocity Fieldsmentioning

confidence: 72%

Two-dimensional spectroscopy of double-barred galaxies

Моисеев

2002

Astron. Lett.

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“…They follow Stasińska et al (2008) in ascribing this emission to a purely stellar origin, and particularly post-Asymptotic Giant Branch (p-AGB) stars. However, NGC 5850 may have recently had a high-velocity encounter with the nearby elliptical galaxy NGC 5846 (Higdon, Buta, & Purcell 1998) raising the possibility that shock excitation may also be involved.…”

Section: Sources Of Emission Linesmentioning

confidence: 99%

Discovery of kpc-scale line emission in barred galaxies, not linked to AGN or star formation.

James

Percival

2015

Monthly Notices of the Royal Astronomical Society

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We present an analysis of the optical line emission from nearby barred galaxies, and in particular look at the radial range occupied by the bar. In many cases this region is marked by what we term a 'star formation desert', with a marked deficit of HII regions in optical narrow-band Hα imaging. Here we present long-slit spectroscopy revealing that such regions do have line emission, but that it is low-level, spatially smooth and almost ubiquitous. The relative strengths of the Hα and the spectrally adjacent [NII] lines in the regions are completely discrepant from those associated with star formation regions, and more closely match expectations for 'LINER' regions. We quantify the total line emission from these extended, kpc-scale regions, and determine the spurious contribution it would make to the determined star formation rate of these galaxies if interpreted as normal Hα emission. We concur with previous studies that link this 'LINER' emission to old stellar populations, e.g. post-asymptotic giant branch stars, and propose these strongly-barred early-type spirals as a prime location for further tests of such emission.

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“…15a Higdon et al 1998). In the outer parts of NGC 5850, the kinematic PA of H i is about PA kin,outer ≈ −25…”

Section: Kinematic Scenariosmentioning

confidence: 99%

“…2) is surrounded by a (pseudo-) ring. The spiral arms are distorted ∼2 west and southwest from the center, probably due to a recent (<200 Myr) high-velocity encounter with NGC 5846 (Higdon et al 1998), which is 10 to the northwest of NGC 5850. In optical color images, Lourenso et al (2003) found the large scale (primary) bar and the inner (secondary) bar to differ in their projected position angle by −67…”

Section: Introductionmentioning

confidence: 98%

What produces the extended LINER-type emission in the NUGA galaxy NGC 5850?

Bremer

Scharwächter

Eckart

et al. 2013

A&A

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Context. The role of low ionization nuclear emission region (LINER) galaxies within the picture of active galactic nuclei (AGN) has been controversial. It is still not clear whether they host an AGN in a low accretion mode or whether they are not active at all but are instead dominated by alternative ionization mechanisms, namely shocks, winds/outflows, or photoionization by a post-asymptotic giant branch (p-AGB) stellar population. The detection of extended LINER-like emission was often taken as evidence of ionization by stellar components, but this has not been undisputed. Aims. Using optical spectroscopy, we examine the possible ionization mechanisms responsible for the extended LINER-like emission in the central ∼4 kpc of NGC 5850. Methods. We performed integral field spectroscopic observations using VIMOS at the VLT, which provides spatially-resolved spectra for the gas emission and the stellar continuum. We subtract the underlying stellar continuum from the galaxy spectra and fit the emission lines. With these methods, we derive and analyze emission line and kinematic maps. Emission line ratio maps are examined by means of diagnostic diagrams. Results. The central few kpc of NGC 5850 are dominated by extended LINER-like emission. The emission-line ratios that are sensitive to the ionization parameter increase with radial distance to the nucleus. The LINER-like region is surrounded by emission that is classed as "composite" in terms of diagnostic diagrams. Two star-forming (SF) regions are present in the 21 × 19 field of view. One of them is located approximately in the ring, surrounding the kinematically decoupled core. The second one is close to the nucleus and is the origin of a region of decreased emission line ratios oriented radially outwards. We find the interstellar gas to have a complex kinematic morphology and to have areas of steep velocity gradients. Conclusions. The extended LINER-like emission in NGC 5850 is dominated by ionization from distributed ionization sources, probably by stars on the p-AGB. The extended "composite" emission is likely due to a mixture of a LINER-like ionization pattern and photoionization by low-level star formation. With the extended region of decreased emission line ratios, we possibly observe enhanced SF or a region that is shielded from the central LINER-like emission by the central H ii-region. The peculiar gas kinematics are probably caused by the lopsided (m = 1) distribution of the gas and make the inflow of gas toward the center appear possible.

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An Optical and H [CSC]i[/CSC] Study of NGC 5850: Victim of a High-Speed Encounter?

Cited by 36 publications

References 41 publications

Two-dimensional spectroscopy of double-barred galaxies

Two-dimensional spectroscopy of double-barred galaxies

Discovery of kpc-scale line emission in barred galaxies, not linked to AGN or star formation.

What produces the extended LINER-type emission in the NUGA galaxy NGC 5850?

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