Stellar kinematics using a third integral of motion: method and application on the Andromeda galaxy

Kipper, Rain; Tenjes, P.; Tihhonova, O.; Tamm, A.; Tempel, Elmo

doi:10.1093/mnras/stw1194

Cited by 10 publications

(14 citation statements)

References 71 publications

(85 reference statements)

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“…We checked validity of this assumption in case of the Andromeda galaxy, M 31, modelled by us earlier (Kipper et al 2016). In case of the Andromeda galaxy at R = 8 kpc the third integral can be approximated as E z up to z ∼ 0.8 kpc only.…”

Section: Conclusion and Discussionmentioning

confidence: 90%

A method to calculate the local density distribution of the Galaxy from the Tycho-Gaia Astrometric Solution data

Kipper

Tempel

Tenjes

2017

Monthly Notices of the Royal Astronomical Society

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New and more reliable distances and proper motions of a large number of stars in the Tycho-Gaia Astrometric Solution (TGAS) catalogue allow to calculate the local matter density distribution more precisely than earlier.We devised a method to calculate the stationary gravitational potential distribution perpendicular to the Galactic plane by comparing the vertical probability density distribution of a sample of observed stars with the theoretical probability density distribution computed from their vertical coordinates and velocities. We applied the model to idealised test stars and to the real observational samples. Tests with two mock datasets proved that the method is viable and provides reasonable results.Applying the method to TGAS data we derived that the total matter density in the Solar neighbourhood is 0.09 ± 0.02 M pc −3 being consistent with the results from literature. The matter surface density within |z| ≤ 0.75 kpc is 42 ± 4 M pc −2 . This is slightly less than the results derived by other authors but within errors is consistent with previous estimates. Our results show no firm evidence for significant amount of dark matter in the Solar neighbourhood. However, we caution that our calculations at |z| ≤ 0.75 kpc rel on an extrapolation from the velocity distribution function calculated at |z| ≤ 25 pc. This extrapolation can be very sensitive to our assumption that the stellar motions are perfectly decoupled in R and z, and to our assumption of equilibrium. Indeed, we find that ρ(z) within |z| ≤ 0.75 kpc is asymmetric with respect to the Galactic plane at distances |z| = 0.1 − 0.4 kpc indicating that the density distribution may be influenced by density perturbations.

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Section: Conclusion and Discussionmentioning

confidence: 90%

A method to calculate the local density distribution of the Galaxy from the Tycho-Gaia Astrometric Solution data

Kipper

Tempel

Tenjes

2017

Monthly Notices of the Royal Astronomical Society

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“…In this paper, we adopt the mean value of σ z /σ R in the disc-dominated range, between 2 and 10 kpc approximately. In a recent work, Kipper et al (2016) studied the SVE of our neighbor galaxy M 31. It is a well known galaxy and its major axis kinematics had been measured several times (McElroy 1983;Kormendy 1988;van der Marel et al 1994;Kormendy & Bender 1999).…”

Section: Dynamical Models: Schwarzschild Three Integral and Jeans Mementioning

confidence: 99%

Revisiting the stellar velocity ellipsoid–Hubble-type relation: observations versus simulations

Pinna

Falcón-Barroso

Martig

et al. 2018

Monthly Notices of the Royal Astronomical Society

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The stellar velocity ellipsoid (SVE) in galaxies can provide important information on the processes that participate in the dynamical heating of their disc components (e.g. giant molecular clouds, mergers, spiral density waves, bars). Earlier findings suggested a strong relation between the shape of the disc SVE and Hubble type, with later-type galaxies displaying more anisotropic ellipsoids and early-types being more isotropic. In this paper, we revisit the strength of this relation using an exhaustive compilation of observational results from the literature on this issue. We find no clear correlation between the shape of the disc SVE and morphological type, and show that galaxies with the same Hubble type display a wide range of vertical-to-radial velocity dispersion ratios. The points are distributed around a mean value and scatter of σ z /σ R = 0.7 ± 0.2. With the aid of numerical simulations, we argue that different mechanisms might influence the shape of the SVE in the same manner and that the same process (e.g. mergers) does not have the same impact in all the galaxies. The complexity of the observational picture is confirmed by these simulations, which suggest that the vertical-to-radial axis ratio of the SVE is not a good indicator of the main source of disc heating. Our analysis of those simulations also indicates that the observed shape of the disc SVE may be affected by several processes simultaneously and that the signatures of some of them (e.g. mergers) fade over time.

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“…The earlier results of Gerssen & Shapiro Griffin (2012) showed that later type galaxies presented more oblate ellipsoids. On the other hand, P18 analysis of photometric observations (van der Kruit & de Grijs 1999), spectroscopic decomposition of the line of sight (Emsellem, Dejonghe & Bacon 1999;Tempel & Tenjes 2006;Cappellari et al 2007;Kipper et al 2016), and dynamical models (Emsellem et al 1999;Tempel & Tenjes 2006;Cappellari et al 2007;Kipper et al 2016) did not exhibit such relation. In addition, P18 found that the simulations from Martig et al (2012) and Martinez-Valpuesta et al (2017) do not favour a scenario where σ z /σ r is connected with morphology.…”

Section: H U B B L E T Y P E R E L At I O Nmentioning

confidence: 97%

Local variations of the Stellar Velocity Ellipsoid-I: the disc of galaxies in the Auriga simulations

Walo-Martín

Pérez

Grand

et al. 2021

Monthly Notices of the Royal Astronomical Society

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The connection between the Stellar Velocity Ellipsoid (SVE) and the dynamical evolution of galaxies has been a matter of debate in the last years and there is no clear consensus whether different heating agents (e.g. spiral arms, giant molecular clouds, bars and mergers) leave clear detectable signatures in the present day kinematics. Most of these results are based on a single and global SVE and have not taken into account that these agents do not necessarily equally affect all regions of the stellar disc.We study the 2D spatial distribution of the SVE across the stellar discs of Auriga galaxies, a set of high resolution magneto-hydrodynamical cosmological zoom-in simulations, to unveil the connection between local and global kinematic properties in the disc region. We find very similar, global, σz/σr = 0.80 ± 0.08 values for galaxies of different Hubble types. This shows that the global properties of the SVE at z=0 are not a good indicator of the heating and cooling events experienced by galaxies. We also find that similar σz/σr radial profiles are obtained through different combinations of σz and σr trends: at a local level, the vertical and radial components can evolve differently, leading to similar σz/σr profiles at z=0. By contrast, the 2D spatial distribution of the SVE varies a lot more from galaxy to galaxy. Present day features in the SVE spatial distribution may be associated with specific interactions such as fly-by encounters or the accretion of low mass satellites even in the cases when the global SVE is not affected. The stellar populations decomposition reveals that young stellar populations present colder and less isotropic SVEs and more complex 2D distributions than their older and hotter counterparts.

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Stellar kinematics using a third integral of motion: method and application on the Andromeda galaxy

Cited by 10 publications

References 71 publications

A method to calculate the local density distribution of the Galaxy from the Tycho-Gaia Astrometric Solution data

A method to calculate the local density distribution of the Galaxy from the Tycho-Gaia Astrometric Solution data

Revisiting the stellar velocity ellipsoid–Hubble-type relation: observations versus simulations

Local variations of the Stellar Velocity Ellipsoid-I: the disc of galaxies in the Auriga simulations

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