1 / 20

Nuclear Star Clusters and SMBHs: competitive feedback

Nuclear Star Clusters and SMBHs: competitive feedback. Sergei Nayakshin A. King, C. Power, S-H. Cha, A. Hobbs, M. Wilkinson (University of Leicester, UK). SMBHs and NCs. Ferrarese et al 2006 (cf. also Wehner & Harris 06) Black -- SMBH Red -- nuclear star clusters M < 10^8 Msun

mariko-burke
Télécharger la présentation

Nuclear Star Clusters and SMBHs: competitive feedback

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Nuclear Star Clusters and SMBHs:competitive feedback Sergei Nayakshin A. King, C. Power, S-H. Cha, A. Hobbs, M. Wilkinson (University of Leicester, UK)

  2. SMBHs and NCs Ferrarese et al 2006 (cf. also Wehner & Harris 06) Black -- SMBH Red -- nuclear star clusters M < 10^8 Msun R ~ 3-10 pc

  3. Momentum feedback model For massive stars & BH Momentum flux in radiation Radiation drives winds  momentum flux in wind • Observational fact for massive stars • Pounds & King 2003, Pounds + 09 present observational evidence for such winds in SMBH with v ~ 0.1 c

  4. Weight of gas in the bulge For a DM potential with velocity dispersion Grav force (weight) at radius R Force balance King 2003, 2005

  5. Feedback from SMBHs and NCs Ferrarese et al 2006 Black -- SMBH Red -- nuclear star clusters (NCs) M < 10^8 Msun R ~ 3-10 pc

  6. Feedback from star clusters For massive stars Just need to count massive star fraction. For a young cluster with “normal” IMF Matches the observed offset well. McLaughlin, King & Nayakshin 2006

  7. Feedback from SMBHs and NCs Ferrarese et al 2006 Black -- SMBH Red -- nuclear star clusters (NCs) M < 10^8 Msun R ~ 3-10 pc

  8. Why do larger bulges prefer BHs to clusters? Nayakshin, Wilkinson & King 2009: • Time scales are important too. • SMBH growth is limited by the Eddington accretion rate, whereas star formation is not. Whereas star clusters can form on time scales of ~ 0.1 – few Myrs

  9. Bulge dynamical time – sigma relation From observed effective radius vs L and sigma vs L relations • In small (sigma < 100 km/s) bulges SMBH can’t grow quickly enough  such bulges will have “underweight” black holes

  10. Numerical method Spherically symmetric wind test • Nayakshin, Hobbs & Cha 09 • Massless particles used to model photons in Monte Carlo schemes • Absorption-on-the-spot approach used to model rapidly cooling winds • Similar to Dale & Bonnell method.

  11. Simulations in a static isothermal potential • SMBH is at the centre of the potential, radiating at its Eddington limit • A shell of gas is infalling with

  12. Simulations of Momentum Feedback (Nayakshin & Power, submitted)

  13. Fixed BH mass

  14. Eddington limited BH growth

  15. Unsolved problems • Spherically symmetric models -- feedback works, feeding NOT • Disc models – feeding works, feedback does NOT

  16. Summary SMBH and NCs influence their hosts via momentum feedback NCs form when BH fails to catch up with growing bulge No self-consistent model for feedback and feeding yet.

  17. Feedback in cosmological simulations Springel and Di Matteo 2005+++ model Sijacki, Springel + 2007

  18. Thermal feedback • Sazonov, Ostriker, Ciotti & Sunyaev 05: • Radiative heating of gas in the bulge by photoionisation and inverse Compton effect. • T_comp ~ 2 x 10^7 K (Sazonov +04) • Gas can be heated above T_vir

  19. Momentum Feedback: numerical method Source in a constant pressure medium test.  Momentum of wind particles must be << SPH particle momentum

  20. Rotating and moving shell Same DM + BH setup, but the shell is rotating + const v_x

More Related