Modal Approach to the Morphology of Spiral Galaxies. II. Dynamical Mechanisms

Bertin, G.; Lin, C. C.; Löwe, Sandra; Thurstans, R. P.

doi:10.1086/167183

Cited by 147 publications

(135 citation statements)

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“…Although the discrepancies in the classical density wave model were solved with the swing amplification theory (Toomre 1981), there has been very little testing of this theory with observations. Modal studies by Bertin et al (1989aBertin et al ( , 1989b predict that there should be amplitude variations along the arms from resonances between inward-and outward-moving spiral waves, and the precise amplitude variations have been modeled (Elmegreen & Elmegreen 1984;Elmegreen et al 1989;Elmegreen & Thomasson 1993;Regan & Elmegreen 1997). Most recently, a new theory has been proposed for the formation of rings and spiral arms, which argues in favor of chaotic orbits, confined by invariant manifolds emanating from the L1 and L2 Lagrangian points of a bar (Romero-Gómez et al 2007).…”

Section: Spiral Armsmentioning

confidence: 99%

TheSpitzerSurvey of Stellar Structure in Galaxies

Sheth¹,

Regan²,

Hinz³

et al. 2010

Publications of the Astronomical Society of the Pacific

517

501

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ABSTRACT. The Spitzer Survey of Stellar Structure in Galaxies (S 4 G) is an Exploration Science Legacy Program approved for the Spitzer post-cryogenic mission. It is a volume-, magnitude-, and size-limited (d < 40 Mpc, jbj > 30°, m Bcorr < 15:5, and D 25 > 1 0 ) survey of 2331 galaxies using the Infrared Array Camera (IRAC) at 3.6 and 4.5 μm. Each galaxy is observed for 240 s and mapped to ≥1:5 × D 25 . The final mosaicked images have a typical 1σ rms noise level of 0.0072 and 0:0093 MJy sr À1 at 3.6 and 4.5 μm, respectively. Our azimuthally averaged surface brightness profile typically traces isophotes at μ 3:6μm ðABÞð1σÞ ∼ 27 mag arcsec À2 , equivalent to a stellar mass surface density of ∼1 M ⊙ pc À2 . S 4 G thus provides an unprecedented data set for the study of the distribution of mass and stellar structures in the local universe. This large, unbiased, and extremely deep sample of all Hubble types from dwarfs to spirals to ellipticals will allow for detailed structural studies, not only as a function of stellar mass, but also as a function of the local environment. The data from this survey will serve as a vital testbed for cosmological simulations predicting the stellar mass properties of present-day galaxies. This article introduces the survey and describes the sample selection, the significance of the 3.6 and 4.5 μm bands for this study, and the data collection and survey strategies. We describe the S 4 G data analysis pipeline and present measurements for a first set of galaxies, observed in both the cryogenic and warm mission phases of Spitzer. For every galaxy we tabulate the galaxy diameter, position angle, axial ratio, inclination at μ 3:6μm ðABÞ ¼ 25:5, and 26:5 mag arcsec À2 (equivalent to ≈μ B ðABÞ ¼ 27:2 and 28:2 mag arcsec À2 , respectively). These measurements will form the initial S 4 G catalog of galaxy properties. We also measure the total magnitude and the azimuthally averaged radial profiles of ellipticity, position angle, surface brightness, and color. Finally, using the galaxy-fitting code GALFIT, we deconstruct each galaxy into its main constituent stellar components: the bulge/spheroid, disk, bar, and nuclear point source, where necessary. Together, these data products will provide a comprehensive and definitive catalog of stellar structures, mass, and properties of galaxies in the nearby universe and will enable a variety of scientific investigations, some of which are highlighted in this introductory S 4 G survey paper.

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Section: Spiral Armsmentioning

confidence: 99%

TheSpitzerSurvey of Stellar Structure in Galaxies

Sheth¹,

Regan²,

Hinz³

et al. 2010

Publications of the Astronomical Society of the Pacific

517

501

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“…Short trailing stellar density waves can be excited near the CR from long trailing stellar density waves by 'the wave amplification by stimulated emission of radiation' (WASER) in lighter discs (Mark 1974(Mark , 1976, or from short leading density waves by the swing amplification mechanism in heavier discs (Goldreich & Lynden-Bell 1965b;Julian & Toomre 1966;Goldreich & Tremaine 1978;Toomre 1981). With these assumptions, 'standing-wave' patterns 3 can exist between a reflecting radius in the inner part of the galaxy and CR radius, where the waves can be amplified (Bertin et al 1989a(Bertin et al , 1989b. The spiral density waves should be located between, but not reaching the ILR and OLR.…”

Section: Propagation Of Tight-winding Density Wavesmentioning

confidence: 99%

Dawes Review 4: Spiral Structures in Disc Galaxies

Dobbs

Baba

2014

Publ. Astron. Soc. Aust.

248

272

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The majority of astrophysics involves the study of spiral galaxies, and stars and planets within them, but how spiral arms in galaxies form and evolve is still a fundamental problem. Major progress in this field was made primarily in the 1960s, and early 1970s, but since then there has been no comprehensive update on the state of the field. In this review, we discuss the progress in theory, and in particular numerical calculations, which unlike in the 1960s and 1970s, are now commonplace, as well as recent observational developments. We set out the current status for different scenarios for spiral arm formation, the nature of the spiral arms they induce, and the consequences for gas dynamics and star formation in different types of spiral galaxies. We argue that, with the possible exception of barred galaxies, spiral arms are transient, recurrent and initiated by swing amplified instabilities in the disc. We suppose that unbarred m = 2 spiral patterns are induced by tidal interactions, and slowly wind up over time. However the mechanism for generating spiral structure does not appear to have significant consequences for star formation in galaxies.

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“…In the modal theory of spiral structure (Bertin et al 1989a(Bertin et al , 1989b, the corotation resonance is typically located in the outer parts of the optical disk, where the gas-to-star density ratio is larger. The stellar spiral should exhibit a basic continuity across the corotation resonance and a reversal of the properties of the spiral tracers, such as the locations of H ii regions (Bertin 1993).…”

Section: Location Of the Corotation Resonancementioning

confidence: 99%

Dark Matter within High Surface Brightness Spiral Galaxies

Kranz

Slyz²,

Rix

2003

ApJ

107

129

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We present results from a detailed dynamical analysis of five high surface brightness, late-type spiral galaxies, NGC 3810, NGC 3893, NGC 4254, NGC 5676, and NGC 6643, which were studied with the aim of quantifying the luminous-to-dark matter ratio inside their optical radii. The galaxies' stellar light distribution and gas kinematics have been observed and compared to hydrodynamic gas simulations that predict the gasdynamics arising in response to empirical gravitational potentials, which are combinations of differing stellar disk and dark halo contributions. The gravitational potential of the stellar disk was derived from nearinfrared photometry, color corrected to yield a constant stellar mass-to-light ratio (M/L); for the dark halo, the mass density distribution of an axisymmetric isothermal sphere with a core was chosen. Hydrodynamic gas simulations were performed for each galaxy for a sequence of five different mass fractions of the stellar disk and for a wide range of spiral pattern speeds. These two parameters mainly determine the modeled gas distribution and kinematics. The agreement between the simulated and observed gas kinematics permitted us to conclude that the galaxies with the highest rotation velocities tend to possess very massive stellar disks that dominate the gasdynamics within the optical radius. In less massive galaxies, with a maximal rotation velocity of less than 200 km s À1 , the mass of the dark halo at least equals the stellar mass within 2-3 disk scale lengths. The maximal disk stellar mass-to-light ratio in the K band was found to lie at about M=L K % 0:6. Furthermore, the gasdynamic simulations provide a powerful tool for accurately determining the dominant spiral pattern speed for galaxies, independent of a specific density wave theory. It was found that the location of the corotation resonance falls into a narrow range of around three exponential disk scale lengths for all galaxies from the sample. The corotation resonance encloses the strong part of the stellar spiral in all cases. Based on the experience gained from this project, the use of a color correction to account for local stellar population differences is strongly encouraged when properties of galactic disks are studied that rely on their stellar mass distributions.

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Modal Approach to the Morphology of Spiral Galaxies. II. Dynamical Mechanisms

Cited by 147 publications

References 0 publications

TheSpitzerSurvey of Stellar Structure in Galaxies

TheSpitzerSurvey of Stellar Structure in Galaxies

Dawes Review 4: Spiral Structures in Disc Galaxies

Dark Matter within High Surface Brightness Spiral Galaxies

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