Milky Way Structure and Dynamics

Our Galaxy is a prime example of a barred galaxy with a box/peanut bulge. In the last years, we have used NIR star counts to determine the three-dimensional structure of the Galactic bulge and bar. We are using N-body and Made-to-measure particle methods to study the dynamics of the Milky Way bar and bulge, and to determine the distribution of stellar mass and dark matter. We are also investigating the nuclear star cluster around the central black hole in the Galaxy. The possibility to study these components "star-by-star" makes our Milky Way an essential laboratory for understanding the evolutionary history of similar galaxies. 

Main topics

Key publications

Clarke, J. P., Gerhard, O., 2022, MNRAS, 512, 2171
The pattern speed of the Milky Way bar/bulge from VIRAC and Gaia . 2022MNRAS.512.2171C

Wylie, S. M., Clarke, J. P., Gerhard, O., 2022, A&A, 659, A80,
The Milky Way's middle-aged inner ring . 2022A&A...659A..80W

Li, Z., Shen, J., Gerhard, O., Clarke, J. P., 2022, ApJ, 925, 71,
Gas Dynamics in the Galaxy: Total Mass Distribution and the Bar Pattern Speed . 2022ApJ...925...71L

Khoperskov, S., Gerhard, O., arXiv:2111.15211,
Chemo-kinematics of the Milky Way spiral arms and bar resonances: connection to ridges and moving groups in the Solar vicinity . 2021arXiv211115211

Wylie, S. M., Gerhard, O., Ness, M. K., Clarke, J. P., Freeman, K. C., Bland-Hawthorn, J., 2021, A&A, 653,A143,
A2A: 21 000 bulge stars from the ARGOS survey with stellar parameters on the APOGEE scale . 2021A&A...653A.143W

Laporte, C. F. P., Famaey, B., Monari, G., Hill, V., Wegg, C., Gerhard, O., 2020, A&A, 643, L3
Bar resonances and low angular momentum moving groups in the Galaxy revealed by their stellar ages . 2020A&A...643L..3L

Khoperskov, S., Gerhard, O., Di Matteo, P., Haywood, M., Katz, D., Khrapov, S., et al., 2020, A&A, 634, L8.
Hic sunt dracones: Cartography of the Milky Way spiral arms and bar resonances with Gaia Data Release 2 . 2020A&A...634L...8K

Khoperskov, S., Di Matteo, P., Gerhard, O., Katz, D., Haywood, M., Combes, F., et al., 2019, A&A, 622, L6,
The echo of the bar buckling: Phase-space spirals in Gaia Data Release 2. 2019A&A...622L...6K

Wegg, C., Gerhard, O., Bieth, M., 2019, MNRAS, 485, 3296,
The gravitational force field of the Galaxy measured from the kinematics of RR Lyrae in Gaia. 2019MNRAS.485.3296W

Clarke, J. P., Wegg, C., Gerhard, O., Smith, L. C., Lucas, P. W., Wylie, S. M., 2019, MNRAS, 489, 3519
The Milky Way bar/bulge in proper motions: a 3D view from VIRAC & Gaia. 2019MNRAS.489.3519C

Barbuy, B., Chiappini, C., Gerhard, O., 2018, ARA&A, 56, 223,
Chemodynamical History of the Galactic Bulge. 2018ARA&A..56..223B

Portail M., Wegg C., Gerhard O., Ness M., 2017, MNRAS, 470, 1233
Chemodynamical Modelling of the Galactic Bulge and Bar 2017MNRAS.470.1233P

Pérez-Villegas A., Portail M., Wegg C., Gerhard O., 2017, ApJ, 840, L2
Revisiting the Tale of Hercules: how stars orbiting the Lagrange points visit the Sun 2017ApJ...840L...2P

Portail M., Gerhard O., Wegg C., Ness M., 2017, MNRAS, 465, 1621
Dynamical Modelling of the Galactic Bulge and Bar: Pattern Speed, Stellar, and Dark Matter Mass Distributions2017MNRAS.465.1621P

Bland-Hawthorn, J., Gerhard, O., 2016, ARA&A, 54, 529
The Galaxy in Context: Structural, Kinematic, and Integrated Properties. 2016ARA&A..54..529B

Wegg, C., Gerhard, O., Portail, M.,  2015,  MNRAS,  450,  4050,   
The structure of the Milky Way's bar outside the bulge. 2015MNRAS.450.4050W

Portail, M., Wegg, C., Gerhard, O.,  2015,  MNRAS,  450,  L66,   
Peanuts, brezels and bananas: food for thought on the orbital structure of the Galactic bulge. 2015MNRAS.450L..66P

Chatzopoulos, S., Fritz, T. K., Gerhard, O., Gillessen, S., Wegg, C., Genzel, R., et al.,  2015,  MNRAS,  447,  948,   
The old nuclear star cluster in the Milky Way: dynamics, mass, statistical parallax, and black hole mass. 2015MNRAS.447..948C

Wegg, C., Gerhard, O.,  2013,  MNRAS,  435,  1874,   
Mapping the three-dimensional density of the Galactic bulge with VVV red clump stars. 2013MNRAS.435.1874W

Martinez-Valpuesta, I., Gerhard, O.,  2011,  ApJ,  734,  L20,   
Unifying A Boxy Bulge and Planar Long Bar in the Milky Way. 2011ApJ...734L..20M

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