Radiative and Mechanical AGN Feedback in SPH code

1. Radiative and Mechanical AGN Feedback in SPH code Authors: Ena Choi(Princeton), Jeremiah P. Ostriker(Princeton), Thorsten Naab(MPA), & Peter H. Johansson(U. of Helsinki) Poster abstract: We present our new implementation of the momentum mechanical feedback, and X-ray radiation feedback of the black holes (BHs) in the SPH simulation code GADGET. Using the isolated galaxy simulations, we find that overall the black hole growth of new model is similar to that of standard 'thermal' feedback (Springel+05). However, our new mechanical+radiation feedback model has 1. much higher outflowing wind velocities, 2. higher fraction of BH feedback energy (35%) emitted in winds, 3. lower X-ray luminosity that more agrees with observed value, and 4. greater degree of fluctuation in both radiant and wind output. We also test our new BH mass accretion model that restrict accretion to those gravitationally bound to BH. Galaxy Model New BH Feedback model includes: • New momentum-based mechanical feedback based on mass, energy and momentum input (OCCNP10). • The radiative feedback from the electromagnetic-energy component of X–ray radiation of BH (via Compton heating and photoionization heating) (Sazonov+Sunyaev 05 formulae). • The electromagnetic-momentum, i.e., the radiation pressure from the X-ray flux. • The Eddington force acting on the surrounding gas, directed radially away from the BH. (The ‘Eddington limit‘ on the mass accretion rate is removed.) • The Bondi radius criterion: the statistical restriction of accreted elements to those gravitationally bound to the BH. Isolated disk galaxy vvir = 160 km/s rvir = 160 h-1 kpc Mvir = 9.5X1011 h-1 Msun fgas = 0.2 / mbaryon = 0.041 Mgas = 6.4X104 Msun MDM=1.1X106 Msun Initial parameters εr=0.1 / εfeedback=0.005 α= 32 BH growth and Wind property • Standard Thermal Feedback vs. New Mechanical+Radiation Feedback • The final BH masses are similar. • But the new model has the episodic outbursts of mass accretion (LBH ~ Ledd). • The new model has much higher wind velocity ouflows with vw~3000 km/s and Lwind ~ 1041 erg/s. These properties are broadly similar to those observed in some local Seyfert galaxies (Fisher+11). Thermal FB itself cannot easily reproduce the observed fast outflows. • Total energy released by the BH(ΔE=εrεfbΔMBHc2) is 2.2X1058 erg for both FB models. While only 0.1% of the released energy is found in winds in thermal FB model, in the new model, 38% is found in outflowing winds. ΔEwind,tot = 8.3X1057 erg d. ΔEwind,tot = 2.8X1055 erg b. c. a. Phase diagram and X-ray luminosity a. (left) In the thermal feedback model, the energy input by the accreting BH generates collimated, hot and slow winds. This wind particles leave from the high density and hot temperature tip (a.), andemit strong X-rays: LX=1040 erg/s. The X-ray luminosity of the thermal feedback model is much higher than what is typically seen from normal massive spiral galaxies (~1038 erg/s, Almy+00, Boroson+11). (right) As the momentum-driven winds quickly expel and cool the X-ray emitting hot gas, the momentum feedback model has much lower X-ray luminosity (~1036.3 erg/s). a. piure Reference Almy, R. C. et al. 2000, ApJ, 545, 290 Boroson, B., Kim, D.-W., & Fabbiano, G. 2011, ApJ, 729, 12 Fisher, T. C. et al. 2011, ApJ, 727, 71 Ostriker, J. P., Choi, E., Ciotti, L., Novak, G. S., & Proga, D. 2010, ApJ, 722, 642 (OCCNP10) Sazonov, S. Y., Ostriker, J. P., Ciotti, L., & Sunyaev, R. A. 2005, MNRAS, 358, 168 Springel, V., Di Matteo, T., Hernquist, L. 2005, MNRAS, 361, 776 (SdMH05)