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Related papers: A New Method for Determining the Milky Way Bar Pat…

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We construct a large set of dynamical models of the galactic bulge, bar and inner disk using the Made-to-Measure method. Our models are constrained to match the red clump giant density from a combination of the VVV, UKIDSS and 2MASS…

Astrophysics of Galaxies · Physics 2016-12-21 Matthieu Portail , Ortwin Gerhard , Christopher Wegg , Melissa Ness

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…

Astrophysics of Galaxies · Physics 2018-05-16 Olivier Bienaymé

Truly, kinematics in the Solar neighborhood has provided important information both for the structure and for the evolution of the Galaxy since the early 20th century. The relationship between Oort constants and the ratio of the velocity…

Astrophysics of Galaxies · Physics 2021-12-08 W. H. Elsanhoury , M. I. Nouh , Richard L. Branham , Amnah S. Al-Johani

Observational data indicate that the Milky Way is a barred spiral galaxy. Computation facilities and availability of data from Galactic surveys stimulate the appearance of models of the Galactic structure. More efforts to build dynamical…

Astrophysics of Galaxies · Physics 2018-07-18 Tatiana A. Michtchenko , Jacques R. D. Lépine , Douglas A. Barros , Ronaldo S. S. Vieira

We have used 2D Fabry-Perot absorption-line spectroscopy of the SB0 galaxy NGC 7079 to measure its bar pattern speed, $\om$. As in all previous cases of bar pattern speed measurements, we find a fast bar. We estimate that NGC 7079 has been…

Astrophysics · Physics 2007-05-23 V. P. Debattista , T. B. Williams

The length and pattern speed of the Milky Way bar are still controversial. Photometric and spectroscopic surveys of the inner Galaxy, as well as gas kinematics, favour a long and slowly rotating bar, with corotation around a Galactocentric…

Astrophysics of Galaxies · Physics 2017-01-18 Giacomo Monari , Daisuke Kawata , Jason A. S. Hunt , Benoit Famaey

We present an update to the frequency analysis method for measuring the properties of a galactic bar. The method involves computing the fundamental frequencies of orbits in rotating, N-body-derived potential models, classifying the stars as…

Astrophysics of Galaxies · Physics 2026-05-13 Zachary Langford , Robyn Sanderson , Madeline Lucey , Jason A. S. Hunt

We use compiled high-precision pulsar timing measurements to directly measure the Galactic acceleration of binary pulsars relative to the Solar System barycenter. Given the vertical accelerations, we use the Poisson equation to derive the…

Astrophysics of Galaxies · Physics 2021-03-17 Sukanya Chakrabarti , Philip Chang , Michael T. Lam , Sarah J. Vigeland , Alice C. Quillen

We have used the Tremaine-Weinberg method to measure the angular speed of rotation for the bar in the SB0 galaxy NGC 936. With this technique, the bar's pattern speed, Omega_p, can be derived from the luminosity and stellar-kinematic…

Astrophysics · Physics 2015-06-24 Michael R. Merrifield , Konrad Kuijken

Recently the commissioning APOGEE observations of the Galactic bulge reported that a significant fraction of stars ($\sim10%$) are in a cold ($\sigma_{\rm V} \approx 30$ km/s) high velocity peak (Galactocentric radial velocity $\approx 200$…

Astrophysics of Galaxies · Physics 2015-06-18 Zhao-Yu Li , Juntai Shen , R. Michael Rich , Andrea Kunder , Shude Mao

We describe methods to measure simultaneously the orientation angle $\psi$ and pattern speed $\Omega$ from single snapshots of simulated barred galaxies. Unlike previous attempts, our approach is unbiased, precise, and consistent in the…

Astrophysics of Galaxies · Physics 2022-11-16 Walter Dehnen , Marcin Semczuk , Ralph Schoenrich

Spectroscopic surveys now supply precise stellar label measurements such as element abundances for large samples of stars throughout the Milky Way. These element abundances are known to correlate with orbital actions or other dynamical…

Most secular effects produced by stellar bars strongly depend on the pattern speed. Unfortunately, it is also the most difficult observational parameter to estimate. In this work, we measured the bar pattern speed of 97 Milky-Way Analogue…

We find that a steady state bar induces transient features at low velocities in the solar neighborhood velocity distribution due to the initial response of the disc, following the formation of the bar. We associate these velocity streams…

Astrophysics of Galaxies · Physics 2015-05-14 I. Minchev , C. Boily , A. Siebert , O. Bienayme

We perform test-particle simulations in a 2D, differentially rotating stellar disk, subjected to a two-armed steady state spiral density wave perturbation in order to estimate the influence of spiral structure on the local velocity field.…

Astrophysics · Physics 2008-11-26 I. Minchev , A. Quillen

We measure the line-of-sight accelerations of 26 binary pulsars due to the Milky Way's gravitational potential, and produce a 3-dimensional map of the acceleration field of the Galaxy. Acceleration measurements directly give us the change…

Astrophysics of Galaxies · Physics 2024-05-22 Thomas Donlon , Sukanya Chakrabarti , Lawrence M. Widrow , Michael T. Lam , Philip Chang , Alice C. Quillen

The Milky Way has a barred bulge. This article summarizes the current understanding of the main structural parameters and pattern speed of the bar, and compares predicted values for the microlensing optical depth with the bulge microlensing…

Astrophysics · Physics 2008-11-26 Ortwin Gerhard

Based on a high quality $N$-body simulation of a double bar galaxy model, we investigate the evolution of the bar properties, including their size, strength and instantaneous pattern speed derived by using three distinct methods: the…

Astrophysics of Galaxies · Physics 2018-07-11 Yu-Ting Wu , Daniel Pfenniger , Ronald E. Taam

We present a novel method for constraining the length of the Galactic bar using 6D phase space information to directly integrate orbits. We define a pseudo-length for the Galactic bar, named $R_{Freq}$, based on the maximal extent of…

We have estimated the spiral pattern speed in the Galaxy $\Omega_p$ from a large sample of young open star clusters (OSCs). For this purpose, we have used 2494 OSCs younger than 50 Myr. Their mean proper motions, line-of-sight velocities,…

Astrophysics of Galaxies · Physics 2023-09-25 Vadim V. Bobylev , Anisa T. Bajkova