Deriving the pattern speed using dynamical modelling of gas flows in barred galaxies
I. Perez, K. C. Freeman, R. Fux, A. Zurita
备注：
6 pages, 2 figures. To appear in "Tumbling, twisting, and winding galaxies: Pattern speeds along the Hubble sequence", E. M. Corsini and V. P. Debattista (eds.), Memorie della Societa` Astronomica Italiana
In this paper we analyse the methodology to derive the bar pattern speed from dynamical simulations. The results are robust to the changes in the vertical-scale height and in the mass-to-light (M/L) ratios. There is a small range of parameters for which the kinematics can be fitted. We have also taken into account the use of different type of dynamical modelling and the effect of using 2-D vs 1-D models in deriving the pattern speeds. We conclude that the derivation of the bar streaming motions and strength and position of shocks is not greatly affected by the fluid dynamical model used. We show new results on the derivation of the pattern speed for NGC 1530. The best fit pattern speed is around 10 km/s/kpc, which corresponds to a R_cor/R_bar = 1.4, implying a slower bar than previously derived from more indirect assumptions. With this pattern speed, the global and most local kinematic features are beautifully reproduced. However, the simulations fail to reproduce the velocity gradients close to some bright HII regions in the bar. We have shown from the study of the Halpha equivalent widths that the HII regions that are located further away from the bar dust-lane in its leading side, downstream from the main bar dust-lane, are older than the rest by 1.5-2.5 Myr. In addition, a clear spatial correlation was found between the location of HII regions, dust spurs on the trailing side of the bar dust-lane, and the loci of maximum velocity gradients parallel to the bar major axis.
The MaNGA project has obtained IFU data for several thousand nearby galaxies, including barred galaxies. With the two dimensional spectral and kinematic information provided by IFUs, we can measure the pattern speed of a barred galaxy, which determines the bar dynamics. We apply the non-parametric method proposed by Tremaine \& Weinberg to estimate the bar pattern speed for 53 barred galaxies, making this the largest sample studied so far in this way. Our sample is selected from the MaNGA first public data release as part of SDSS Data Release 13 according mainly to the axis ratio and position …
Context: Dust in late-type galaxies in the local Universe is responsible for absorbing approximately one third of the energy emitted by stars. It is often assumed that dust heating is mainly attributable to the absorption of UV and optical photons emitted by the youngest (<= 100 Myr) stars. Consequently, thermal re-emission by dust at FIR wavelengths is often linked to the star-formation activity of a galaxy. However, several studies argue that the contribution to dust heating by much older stars might be more significant. Advances in radiation transfer (RT) simulations finally allow us to act…
Barred structures are important in understanding galaxy evolution, but they were not included explicitly in most dynamical models for nearby galaxies due to their complicated morphological and kinematic properties. We modify the triaxial orbit-superposition Schwarzschild implementation by Van den Bosch et al. (2008) to include barred structures explicitly. The gravitational potential is a combination of a spherical dark matter halo and stellar mass; with the 3D stellar density distribution de-projected from the observed 2D image using a two-component de-projection method, including an axisymme…
We study the kinematics of stellar disc populations within the solar neighbourhood in order to find the imprints of the Galactic bar. We carry out the analysis by developing a numerical resolution of the 2D2V Collisionless Boltzmann Equation (CBE) and modelling the stellar motions within the plane of the Galaxy within the solar neighbourhood. We recover similar results to these obtained by different authors using N-body simulations, but we can also numerically identify faint structures thanks to the canceling of the Poisson noise. We find that the ratio of the bar pattern speed to the local ci…
We present a spectroscopic analysis of the central disc regions of barred spiral galaxies, concentrating on the region that is swept by the bar but not including the bar itself (the `Star Formation Desert' or SFD region). New spectroscopy is presented for 34 galaxies, and the full sample analysed comprises 48 SBa - SBcd galaxies. These data confirm the full suppression of star formation within the SFD regions of all but the latest type (SBcd) galaxies. However, diffuse [NII] and H alpha line emission is detected in all galaxies. The ubiquity and homogeneous properties of this emission from SBa…
In this work we analyse the structural and photometric properties of 21 barred simulated galaxies from the Auriga Project. These consist of Milky Way-mass magneto-hydrodynamical simulations in a $Λ$CDM cosmological context. In order to compare with observations, we generate synthetic SDSS-like broad-band images from the numerical data at z = 0 with different inclinations (from face-on to edge-on). Ellipse fits are used to determine the bar lengths, and 2D bulge/disc/bar decompositions with galfit are also performed, modelling the bar component with the modified Ferrer profile. We find a wide r…
SchwarMAX: a GPU-friendly Schwarzschild orbit-superposition modelling framework
Institute of Astronomy, University of Cambridge（剑桥大学天文研究所）；University of Surrey（萨里大学）；Department of Astronomy, School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院天文学系）；State Key Laboratory of Dark Matter Physics, School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院暗物质物理国家重点实验室）；Key Laboratory for Particle Astrophysics and Cosmology (MOE)/Shanghai Key Laboratory for Particle Physics and Cosmology（粒子天体物理学和宇宙学教育部重点实验室/上海粒子物理和宇宙学重点实验室）
NOEMA$^{\rm 3D}$: A first kpc resolution study of a $z\sim1.5$ main sequence barred galaxy channeling gas into a growing bulge
Max-Planck-Institut für Extraterrestrische Physik (MPE)（马克斯·普朗克地外物理学研究所）；Max-Planck-Institut für Astrophysik (MPA)（马克斯·普朗克天体物理学研究所）；University of California, Berkeley（加州大学伯克利分校）；Institut de Radioastronomie Millimétrique (IRAM)（毫米波射电天文研究所）；Universitäts-Sternwarte Ludwig-Maximilians-Universität (USM)（路德维希-马克西米利安大学大学天文台）
The centres of disc galaxies host a variety of structures built via both internal and external processes. In this study, we constrain the formation and evolution of these central structures, in particular nuclear rings and nuclear discs, by deriving maps of mean stellar ages, metallicities and [$α$/Fe] abundances. We use observations obtained with the MUSE integral-field spectrograph for the TIMER sample of 21 massive barred galaxies. Our results indicate that nuclear discs and nuclear rings are part of the same physical component, with nuclear rings constituting the outer edge of nuclear disc…
Panchromatic spectral energy distribution (SED) fitting is a critical tool for determining the physical properties of distant galaxies, such as their stellar mass and star formation rate. One widely used method is the publicly available MAGPHYS code. We build on our previous analysis (Hayward & Smith 2015) by presenting some modifications which enable MAGPHYS to automatically estimate galaxy star formation histories (SFHs), including uncertainties, based on ultra-violet to far-infrared photometry. We use state-of-the art synthetic photometry derived by performing three-dimensional dust radiati…
Some observations indicate that the Milky Way has two inner components, a bulge and a long bar, which present a misalignment of about 20 degrees that is against the predictions of some theoretical models that are based on numerical simulations. In this paper, we wish to determine whether this misalignment between the bar and the bulge can be observed in barred galaxies other than the Milky Way. For that, each galaxy of our sample was decomposed based on its Ks-band 2MASS image by fitting and modelling in a three-dimensional (3D) space the following components: a disc, a bar, and a bulge. The c…
We present the first self-consistent chemodynamical model fitted to reproduce data for the galactic bulge, bar and inner disk. We extend the Made-to-Measure method to an augmented phase-space including the metallicity of stars, and show its first application to the bar region of the Milky Way. Using data from the ARGOS and APOGEE (DR12) surveys, we adapt the recent dynamical model from Portail et al. to reproduce the observed spatial and kinematic variations as a function of metallicity, thus allowing the detailed study of the 3D density distributions, kinematics and orbital structure of stars…
We examine the effects that the modelling of a Boxy/Peanut (B/P) bulge will have on the estimates of the stellar gravitational potential, forces, orbital structure and bar strength of barred galaxies. We present a method for obtaining the potential of disc galaxies from surface density images, assuming a vertical density distribution (height function), which is let to vary with position, thus enabling it to represent the geometry of a B/P. We construct a B/P height function after the results from a high-resolution, N-body+SPH simulation of an isolated galaxy and compare the resulting dynamical…
More than 10% of the barred galaxies with a direct measurement of the bar pattern speed host an ultrafast bar. These bars extend beyond the corotation radius and challenge our understanding of the orbital structure of barred galaxies. Most of them are found in spiral galaxies, rather than in lenticular ones. We analysed the properties of the ultrafast bars detected in the CALIFA Survey to investigate whether they are an artefact resulting from an overestimation of the bar radius and/or an underestimation of the corotation radius or a new class of bars, whose orbital structure has not yet been …
The Local Tremaine-Weinberg Method for Galactic Pattern Speed: Theory and its Application to IllustrisTNG
National Astronomical Observatories Chinese Academy of Sciences（中国科学院国家天文台）；School of Astronomy and Space Science University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）；Innovation Academy for Microsatellites Chinese Academy of Sciences（中国科学院微小卫星创新研究院）
We present a pilot study on the nearby massive barred galaxy NGC 1291, in which we use dynamical modelling to constrain the disc mass-to-light ratio (M/L), thus breaking the degeneracy between the baryonic and dark matter in its central regions. We use the gas, specifically the morphology of the dust lanes on the leading side of the bar, as a tracer of the underlying gravitational potential. We run a large number of hydrodynamic gas response simulations, in potentials obtained directly from near-infrared images of the galaxy, which have three free parameters: the M/L, the bar pattern speed and…
WISDOM Project -- XXV. Improving the CO-dynamical supermassive black hole mass measurement in the galaxy NGC 1574 using high spatial resolution ALMA observations
We present photometric models of 532 disk galaxies in 3.6μm images from the Spitzer Survey of Stellar Structure in Galaxies (S$^4$G) using the non-parametric DiskFit algorithm. We first test DiskFit's performance on 400 synthetic S$^4$G-like galaxy images. DiskFit is unreliable in the bulge region, but accurately disentangles exponential disks from Ferrers bars farther out as long as their position angles differ by more than 5${^\circ}$. We then proceed to model the S$^4$G galaxies, successfully fitting 489 of them using an automated approach for initializing DiskFit, optimizing the model and …
A spectroscopic map of the Galactic centre: Integrated light and dynamical modelling
University of Vienna（维也纳大学）；SDB Science-driven Business Ltd.（SDB科学驱动商业有限公司）；Instituto de Astrofísica e Ciências do Espaço, Universidade de Lisboa（里斯本大学空间与天体物理研究所）
利用DYNAMITE代码对银河系中心内~3 pc x 66 pc区域的恒星视线运动学进行三轴轨道动力学建模，成功恢复Sgr A*质量并约束质量分布和轨道分布。
We investigate the link between the bar rotation rate and dark matter content in barred galaxies by concentrating on the cases of the lenticular galaxies NGC4264 and NGC4277. These two gas-poor galaxies have similar morphologies, sizes, and luminosities. But, NGC4264 hosts a fast bar, which extends to nearly the corotation, while the bar embedded in NGC4277 is slow and falls short of corotation. We derive the fraction of dark matter $f_{\rm DM, bar}$ within the bar region from Jeans axisymmetric dynamical models by matching the stellar kinematics obtained with the MUSE integral-field spectrogr…
