Tidal disruption events in post-starburst galaxies: the importance of a complete stellar mass function
Abstract
A tidal disruption event (TDE) occurs when a star is destroyed by the strong tidal shear of a massive black hole (MBH). The accumulation of TDE observations over the last years has revealed that post-starburst galaxies are significantly overrepresented in the sample of TDE hosts. Here we address the post-starburst preference by investigating the decline of TDE rates in a Milky-Way like nuclear stellar cluster featuring either a monochromatic (1 $\, \mathrm{M}{\odot {}}$) or a complete, evolved stellar mass function. In the former case, the decline of TDE rates with time is very mild, and generally up to a factor of a few in 10 Gyr. Conversely, if a complete mass function is considered, a strong TDE burst over the first 0.1-1 Gyr is followed by a considerable rate drop, by at least an order of magnitude over 10 Gyr. The decline starts after a mass segregation time-scale, and it is more pronounced assuming a more top-heavy initial mass function and/or an initially denser nucleus. Our results thus suggest that the post-starburst preference can be accounted for in realistic systems featuring a complete stellar mass function, even in moderately dense galactic nuclei. Overall, our findings support the idea that starbursting galactic nuclei are characterized by a top-heavy initial mass function; we speculate that accounting for this can reconcile the discrepancy between observed and theoretically predicted TDE rates even in quiescent galaxies.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 2022
- DOI:
- 10.1093/mnras/stac262
- arXiv:
- arXiv:2201.08397
- Bibcode:
- 2022MNRAS.511.2885B
- Keywords:
-
- black hole physics;
- methods: numerical;
- stars: kinematics and dynamics;
- stars: luminosity function;
- mass function;
- galaxies: kinematics and dynamics;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Instrumentation and Methods for Astrophysics;
- Astrophysics - Solar and Stellar Astrophysics;
- 85A05
- E-Print:
- 12 pages, 7 figures, 1 table. Accepted for publication in MNRAS. Corrected typo in Equation (1)