Hi, I'm Anja Feldmeier-Krause,
welcome to my personal homepage!

My research

Nuclear star clusters are common objects in nearby galaxies. They are dense stellar systems, located at the center of galaxies.

Because the Milky Way nuclear star cluster is at a distance of only 8 kpc, we can spatially resolve its stellar populations and kinematics much better than in external galaxies. This makes the Milky Way nuclear star cluster a reference object for understanding the structure and assembly history of all nuclear star clusters.

I study the stellar kinematics of the Milky Way nuclear star cluster in integrated light towards the half-light radius (4.2pc). I run axisymmetric Jeans models and triaxial Schwarzschild models to understand the large-scale kinematics of the Milky Way nuclear star cluster.

With near-infrared K-band spectroscopy of single resolved stars obtained with KMOS (VLT), I study the star formation history and metallicity distribution of the Milky Way nuclear star cluster. The data extend to a larger spatial scale than previous stellar populations studies of the Galactic centre. The dashed circle denotes the effective radius at 4.2 pc.

The mean metallicity of stars in the NSC is super-solar, though there is a wide range of metallicities. In the Galactic North and East of the NSC, the fraction of stars with sub-solar metallicity is ~30%, but only ~10% in the Galactic South.

Massive early-type galaxies are thought to have formed in two main stages: in an early (z~2) collapse of gas, stars formed in situ in a compact core. The second stage is ongoing to the present: satellite galaxies are accreted and deliver stars to the galaxy that were formed ex situ.

Most early-type galaxies show only little recent star formation, their stellar mass is dominated by old stars, and we can learn about galaxy assembly and early star formation from their stellar populations.

I use optical long-slit spectroscopy to extract information about the stellar populations of early-type galaxies as a function of their radius, out to ~1 effective radius. I fit the spectra with single stellar population models and constrain the stellar age, metallicity, elemental abundances, and low-mass IMF slope.

• The Stellar Initial Mass Function and Population Properties of M89 from Optical and NIR Spectroscopy: Addressing Biases in Spectral Index Analysis
  Lonoce, I.; Feldmeier-Krause, A.; Freedman, W.L.
  ApJ, accepted
  
• The nuclear stellar disc of the Milky Way: A dynamically cool and metal-rich component possibly formed from the central molecular zone
  Schultheis, M.; Fritz, T. K.; Nandakumar, G.; Rojas-Arriagada, A.; Nogueras-Lara, F.; Feldmeier-Krause, A.; Gerhard, O.; Neumayer, N.; Patrick, L. R.; Prieto, M. A.; Schödel, R.; Mastrobuono-Battisti, A.; Sormani, M. C.
  Astronomy & Astrophysics, Volume 650, 6/2021
  
• A KMOS survey of the nuclear disk of the Milky Way. I. Survey design and metallicities
  Fritz, T. K.; Patrick, L. R.; Feldmeier-Krause, A.; Schödel, R.; Schultheis, M.; Gerhard, O.; Nandakumar, G.; Neumayer, N.; Nogueras-Lara, F.; Prieto, M. A.
  Astronomy & Astrophysics, Volume 649, 5/2021
  
• Shadows in the Dark: Low-surface-brightness Galaxies Discovered in the Dark Energy Survey
  Tanoglidis, D.; Drlica-Wagner, A.; Wei, K.; Li, T. S.; Sanchez, J.; Zhang, Y.; Peter, A. H. G.; Feldmeier-Krause, A.; Prat, J.; Casey, K.; Palmese, A.; et al.
  ApJS, Volume 252, 2/2021
  
• Measuring the Stellar Population Parameters of the Early-type Galaxy NGC 3923: The Challenging Measurement of the Initial Mass Function
  Feldmeier-Krause, A.; Lonoce, I.; Freedman, W.L.
  ApJ, Volume 902, 10/2020
  
• On the Origin of a Rotating Metal-poor Stellar Population in the Milky Way Nuclear Cluster
  Arca Sedda, M.; Gualandris, A.; Do, T.; Feldmeier-Krause, A.; Neumayer, N.; Erkal, D.
  ApJL, Volume 901, 10/2020
  
• Revealing the Formation of the Milky Way Nuclear Star Cluster via Chemo-dynamical Modeling
  Do, T.; David Martinez, G.; Kerzendorf, W.; Feldmeier-Krause, A.; Arca Sedda, M.; Neumayer, N.; Gualandris, A.
  ApJL, Volume 901, 10/2020
  
• Three-dimensional Analysis of the Minispiral at the Galactic Center: Orbital Parameters, Periods, and the Mass of the Black Hole
  Nitschai, M. S.; Neumayer, N.; Feldmeier-Krause, A.
  ApJ, Volume 896, 6/2020
  
• Asymmetric spatial distribution of subsolar metallicity stars in the Milky Way nuclear star cluster
  Feldmeier-Krause, A.; Kerzendorf, W.; Do, T.; Nogueras-Lara, F.; Neumayer, N.; Walcher, C. J.; Seth, A., Schödel, R., de Zeeuw, P. T.; Hilker, M.; Lützgendorf, N.; Kuntschner, H.; Kissler-Patig, M.
  MNRAS, Volume 494, 5/2020
  
• Early formation and recent starburst activity in the nuclear disk of the Milky Way
  Nogueras-Lara, F.; Schödel, R.; Gallego-Calvente, A. T.; Gallego-Cano, E.; Shahzamanian, B.; Dong, H.; Neumayer, N.; Hilker, M.; Najarro, F.; Nishiyama, S.; Feldmeier-Krause, A.; Girard, J. H. V.; Cassisi, S.
  Nature Astronomy, Volume 4, 1/2020
  
• Star formation history and metallicity in the Galactic inner bulge revealed by the red giant branch bump
  Nogueras-Lara, F.; Schödel, R.; Dong, H.; Najarro, F.; Gallego-Calvente, A. T.; Hilker, M.; Gallego-Cano, E.; Nishiyama, S.; Neumayer, N.; Feldmeier-Krause, A.; Girard, J. H. V.; Cassisi, S.; Pietrinferni, A.
  Astronomy & Astrophysics, Volume 620, 12/2018
  
• GALACTICNUCLEUS: A high angular resolution JHKs imaging survey of the Galactic centre. I. Methodology, performance, and near-infrared extinction towards the Galactic centre
  Nogueras-Lara, F.; Gallego-Calvente, A. T.; Dong, H.; Gallego-Cano, E.; Girard, J. H. V.; Hilker, M.; de Zeeuw, P. T.; Feldmeier-Krause, A.; Nishiyama, S.; Najarro, F.; Neumayer, N.; Schödel, R.
  Astronomy & Astrophysics, Volume 610, 3/2018
  
• Near-infrared spectroscopic observations of massive young stellar object candidates in the central molecular zone
  Nandakumar, G.; Schultheis, M.; Feldmeier-Krause, A.; Schödel, R.; Neumayer, N.; Matteucci, F.; Ryde, N.; Rojas-Arriagada, A.; Tej, A.
  Astronomy & Astrophysics, Volume 609, 1/2018
  
• Triaxial orbit-based modelling of the Milky Way nuclear star cluster
  Feldmeier-Krause, A.; Zhu, L,; Neumayer, N.; van de Ven, G.; de Zeeuw, P. T.; Schödel, R.
  MNRAS, Volume 466, 4/2017
  
• KMOS view of the Galactic Centre - II. Metallicity distribution of late-type stars
  Feldmeier-Krause, A.; Kerzendorf, W.; Neumayer, N.; Schödel, R.; Nogueras-Lara, F.; Do, T.; de Zeeuw, P. T.; Kuntschner, H.
  MNRAS, Volume 464, 1/2017
  
• KMOS view of the Galactic centre: I. Young Stars are centrally concentrated
  Feldmeier-Krause, A.; Neumayer, N.; Schödel, R.; Seth, A.; Hilker, M.; de Zeeuw, P. T.; Kuntschner, H.; Walcher, C. J.; Lützgendorf, N.; Kissler-Patig, M.
  Astronomy & Astrophysics, Volume 584, 12/2015
  
• The nuclear cluster of the Milky Way: our primary testbed for the interaction of a dense star cluster with a massive black hole
  Schödel, R.; Feldmeier, A.; Neumayer, N.; Meyer, L.; Yelda, S.
  Classical and Quantum Gravity, Volume 31, Issue 24, 12/2014
  
• Large scale kinematics and dynamical modelling of the Milky Way nuclear star cluster
  Feldmeier, A.; Neumayer, N.; Seth, A.; Schödel, R.; Lützgendorf, N.; de Zeeuw, P. T.; Kissler-Patig, M.; Nishiyama, S.; Walcher, C. J.
  Astronomy & Astrophysics, Volume 570, 10/2014
  
• Surface brightness profile of the Milky Way's nuclear star cluster
  Schödel, R.; Feldmeier, A.; Kunneriath, D.; Stolovy, S.; Neumayer, N.; Amaro-Seoane, P.; Nishiyama, S.
  Astronomy & Astrophysics, Volume 566, 6/2014
  
• M_bh - sigma-relation for intermediate-mass black holes in globular clusters
  Lützgendorf, N.; Kissler-Patig, M.; Neumayer, N.; Baumgardt, H.; Noyola, E.; de Zeeuw, P. T.; Gebhardt, K.; Jalali, B.; Feldmeier, A.
  Astronomy & Astrophysics, Volume 555, 7/2013
  
• Indication for an intermediate-mass black hole in the globular cluster NGC 5286 from kinematics
  Feldmeier, A.; Lützgendorf, N.; Neumayer, N.; Kissler-Patig, M.; Gebhardt, K.; Baumgardt, H.; Noyola, E.; de Zeeuw, P. T.; Jalali, B.
  Astronomy & Astrophysics, Volume 554, 6/2013
  
• Limits on intermediate-mass black holes in six Galactic globular clusters with integral-field spectroscopy
  Lützgendorf, N.; Kissler-Patig, M.; Gebhardt, K.; Baumgardt, H.; Noyola, E.; de Zeeuw, P. T.; Neumayer, N.; Jalali, B.; Feldmeier, A.
  Astronomy & Astrophysics, Volume 552, 4/2013
  

Conferences and Selected Talks