Variation of Galactic Bar Length with Amplitude and Density as Evidence for Bar Growth over a Hubble Time

Elmegreen, Bruce G.; Elmegreen, D. M.; Knapen, Johan H.; Buta, Ronald J.; Block, David L.; Puerari, I.

doi:10.1086/524359

Cited by 53 publications

(79 citation statements)

References 22 publications

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“…The length is the radius of the maximum ellipticity, r ε . As an upper limit of bar length, Erwin & Sparke (2003) and Erwin (2005 have used the first minimum in the ellipticity profile after r ε , named as L bar . However, as discussed in Michel- Dansac & Wozniak (2006), the location and value of such a minimum depends on the galaxy inclination and/or the real non-axisymmetric shape of the disk and the type of bar profiles, which is obvious also from the S 4 G images.…”

Section: Estimation Of Bar Lengths and Ellipticitiesmentioning

confidence: 99%

“…15 and 16 (see also Table 3), where the distributions of bar strengths and lengths are shown separated for the different bar families. Erwin (2005) concluded that strong (SB) and weak (SAB) bars hosted by early-type galaxies differ primarily in ellipticity, being very similar in size, while SB bars in late-type spiral galaxies are twice as large as SAB bars. We observe that SB, SAB, SAB, and SAB bars differ in ellipticity as well as in A a difference between weak and strong bars for the bar sizes, as visually categorized: SB and SAB galaxies are ∼10−15% longer relative to the disk size.…”

Section: Bar Parameters and The Family Classmentioning

confidence: 99%

“…Observational evidence of this evolution has been investigated by different groups (e.g. Elmegreen et al 2007;Laurikainen et al 2007;Gadotti 2011). Elmegreen et al (2007) reported a correlation between r A 2 (normalized to R 25 ) and A max 2 , present for early and intermediatetype spiral galaxies based on the H-band and K s -band measurements by Laurikainen et al (2006Laurikainen et al ( , 2004b.…”

Section: Growth Of Barsmentioning

confidence: 99%

“…Another indirect method is provided by studying dust lanes, whose curvature is inversely proportional to the bar strength according to the studies of Athanassoula (1992) (probed in Knapen et al 2002;Comerón et al 2009;Sánchez-Menguiano et al 2015), or by 2D decomposition, fitting generalized ellipses to the bar component and using the boxyness as a proxy of the bar strength (Gadotti 2011). Bar lengths have also been measured by different methods in the literature (for a detailed review see Erwin 2005, hereafter E2005) such as ellipse fitting to bar isophotes (e.g. Wozniak et al 1995), Fourier analysis of the images based on the bar-interbar luminosity contrast or phase (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of galactic bars from 3.6μm S⁴G imaging

Díaz-García

Salo

Laurikainen

et al. 2016

A&A

140

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Context. Stellar bars play an essential role in the secular evolution of disk galaxies because they are responsible for the redistribution of matter and angular momentum. Dynamical models predict that bars become stronger and longer in time, while their rotation speed slows down. Aims. We use the Spitzer Survey of Stellar Structure in Galaxies (S 4 G) 3.6 µm imaging to study the properties (length and strength) and fraction of bars at z = 0 over a wide range of galaxy masses (M * ≈ 10 8 −10 11 M ) and Hubble types (−3 ≤ T ≤ 10). Methods. We calculated gravitational forces from the 3.6 µm images for galaxies with a disk inclination lower than 65• . We used the maximum of the tangential-to-radial force ratio in the bar region (Q b ) as a measure of the bar-induced perturbation strength for a sample of ∼600 barred galaxies. We also used the maximum of the normalized m = 2 Fourier density amplitude (A max 2 ) and the bar isophotal ellipticity (ε) to characterize the bar. Bar sizes were estimated i) visually; ii) from ellipse fitting; iii) from the radii of the strongest torque; and iv) from the radii of the largest m = 2 Fourier amplitude in the bar region. By combining our force calculations with the H  kinematics from the literature, we estimated the ratio of the halo-to-stellar mass (M h /M * ) within the optical disk and by further using the universal rotation curve models, we obtained a first-order model of the rotation curve decomposition of 1128 disk galaxies. Results. We probe possible sources of uncertainty in our Q b measurements: the assumed scale height and its radial variation, the influence of the spiral arms torques, the effect of non-stellar emission in the bar region, and the dilution of the bar forces by the dark matter halo (our models imply that only ∼10% of the disks in our sample are maximal). We find that for early-and intermediate-type disks (−3 ≤ T < 5), the relatively modest influence of the dark matter halo leads to a systematic reduction of the mean Q b by about 10−15%, which is of the same order as the uncertainty associated with estimating the vertical scale height. The halo correction on Q b becomes important for later types, implying a reduction of ∼20−25% for T = 7−10. Whether the halo correction is included or not, the mean Q b shows an increasing trend with T . However, the mean A max 2 decreases for lower mass late-type systems. These opposing trends are most likely related to the reduced force dilution by bulges when moving towards later type galaxies. Nevertheless, when treated separately, both the early-and late-type disk galaxies show a strong positive correlation between Q b and A max 2 . For spirals the mean ε ≈ 0.5 is nearly independent of T , but it drops among S0s (≈0.2). The Q b and ε show a relatively tight dependence, with only a slight difference between early and late disks. For spirals, all our bar strength indicators correlate with the bar length (scaled to isophotal size). Late-type bars are longer than previously found in the literature. The bar fraction...

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Section: Estimation Of Bar Lengths and Ellipticitiesmentioning

confidence: 99%

Section: Bar Parameters and The Family Classmentioning

confidence: 99%

Section: Growth Of Barsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Characterization of galactic bars from 3.6μm S⁴G imaging

Díaz-García

Salo

Laurikainen

et al. 2016

A&A

140

182

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“…Elmegreen et al (1990) reported an increased fraction of bars in groups and clusters, but more recent work (Barazza et al 2009;Li et al 2009;Aguerri et al 2009) has found little or no variation of bar fraction with environment. It is also possible that the bar fraction could be changing with time; different groups disagree (Jogee et al 2004;Sheth et al 2008), probably because observations of galaxies at significant look-back times are subject to systematic difficulties due to band-shifting and changing spatial resolution (see also Elmegreen et al 2007).…”

Section: Frequency Of Barsmentioning

confidence: 99%

Dynamics of Disks and Warps

Sellwood

2013

Planets, Stars and Stellar Systems

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This chapter reviews theoretical work on the stellar dynamics of galaxy disks. All the known collective global instabilities are identified, and their mechanisms described in terms of local wave mechanics. A detailed discussion of warps and other bending waves is also given. The structure of bars in galaxies, and their effect on galaxy evolution, is now reasonably well understood, but there is still no convincing explanation for their origin and frequency. Spiral patterns have long presented a special challenge, and ideas and recent developments are reviewed. Other topics include scattering of disk stars and the survival of thin disks.

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Rings and Bars: Unmasking Secular Evolution of Galaxies

Knapen

2010

Galaxies and Their Masks

Self Cite

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Secular evolution gradually shapes galaxies by internal processes, in contrast to early cosmological evolution which is more rapid. An important driver of secular evolution is the flow of gas from the disk into the central regions, often under the influence of a bar. In this paper, we review several new observational results on bars and nuclear rings in galaxies. They show that these components are intimately linked to each other, and to the properties of their host galaxy. We briefly discuss how upcoming observations, e.g., imaging from the Spitzer Survey of Stellar Structure in Galaxies (S 4 G), will lead to significant further advances in this area of research.

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Variation of Galactic Bar Length with Amplitude and Density as Evidence for Bar Growth over a Hubble Time

Cited by 53 publications

References 22 publications

Characterization of galactic bars from 3.6μm S⁴G imaging

Characterization of galactic bars from 3.6μm S⁴G imaging

Dynamics of Disks and Warps

Rings and Bars: Unmasking Secular Evolution of Galaxies

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Variation of Galactic Bar Length with Amplitude and Density as Evidence for Bar Growth over a Hubble Time

Cited by 53 publications

References 22 publications

Characterization of galactic bars from 3.6μm S4G imaging

Characterization of galactic bars from 3.6μm S4G imaging

Dynamics of Disks and Warps

Rings and Bars: Unmasking Secular Evolution of Galaxies

Contact Info

Product

Resources

About

Characterization of galactic bars from 3.6μm S⁴G imaging

Characterization of galactic bars from 3.6μm S⁴G imaging