Research

Overview

My scientific interest revolves around massive star clusters that occupy galaxy centers, also known as nuclear star clusters, as pictured in the below figure. These clusters are interesting for several reasons. For example, ...

• ...their extreme central densities can cause several exotic phenomena, such as merger events of stars and stellar remnant, causing high-energy phenomena that include gravitational wave emission;
• ...they frequently host and interact with massive black holes;
• ...their formation mechanisms are related to both massive star clusters that formed outside and migrated towards the galaxy center, and central star formation.

  

To study nuclear star clusters I use observational data from SRG/eROSITA mission and the Hubble and James Webb Space Telescope, thus, studying them across a large wavelength range from X-rays to the mid-infrared regime. In addition and more recently, I develop a new version of the semi-analytical model "L-Galaxies" that models the assembly and evolution of star clusters, including the nuclear star cluster, in a cosmological simulation of galaxy formation.

List of publications

Below is a (potentially incomplete) list of my publications, which you can also find on the NASA/ADS.

1. Demographics of tidal disruption events with L-Galaxies I. Volumetric TDE rates and the abundance of nuclear star clusters
   M. Polkas, S. Bonoli, E. Bortolas, et al. (including N. Hoyer)
   Published in A&A, 689, A25 (2024)
   
2. Efficiency of black hole formation via collisions in stellar systems
   M. C. Vergara, D. R. G. Schleicher, A. Escala, et al. (including N. Hoyer)
   Published in A&A, 689, A34 (2024)
   
3. Massive black holes in nuclear star clusters: An investigation with SRG/eROSITA X-ray data
   N. Hoyer, R. Arcodia, S. Bonoli, A. Merloni, N. Neumayer, Y. Zhang, J. Comparat
   Published in A&A, 682, A36 (2024)
   
4. Photometric and Structural Parameters of Newly Discovered Nuclear Star Clusters in Local Volume Galaxies
   N. Hoyer, N. Neumayer, I. Y. Georgiev, et al.
   Published in MNRAS, 520, 4664-4682 (2023)
   
5. Serendipitous Nebular-phase JWST Imaging of SN Ia SN 2021aefx: Testing the Confinement of 56Co Decay Energy
   N. Mayker Chen, M. A. Tucker, N. Hoyer, et al.
   Published in ApJL, 944, L28 (2023)
   
6. PHANGS-JWST First Results: A combined HST and JWST analysis of the nuclear star cluster in NGC628
   N. Hoyer, F. Pinna, A. W. H. Kamlah, et al.
   Published in ApJL, 944, L25 (2023)
   
7. The PHANGS-JWST Treasury Survey: Star Formation, Feedback, and Dust Physics at High Angular Resolution in Nearby GalaxieS
   J. Lee, K. M. Sandstrom, A. K. Leroy et al. (including N. Hoyer)
   Published in ApJL, 944, L17 (2023)
   
8. The black hole population in low-mass galaxies in large-scale cosmological simulations
   H. Haidar, M. Habouzit, M. Volonteri et al. (including N. Hoyer)
   Published in MNRAS, 514, 4912-4931 (2022)
   
9. The nucleation fraction of Local Volume galaxies
   N. Hoyer, N. Neumayer, I. Y. Georgiev, et al.
   Published in MNRAS, 507, 3246-3266 (2021)
   
10. 3C 294 revisited: Deep Large Binocular Telescope AO NIR images and optical spectroscopy
    J. Heidt, A. Quirrenbach, N. Hoyer et al.
    Published in A&A, 628, A28 (2019)

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