Speaker: Bingxiao Xu Peking University Galaxy Bulge Formation: Interplay with Dark Matter Halo and Central Supermassive Black Hole Speaker: Bingxiao Xu Peking University

Outline Introduction Galaxy Bulge Formation (Gravothermal Instability) Stellar Feedback in Bulge Formation Obscured Black Hole Growth Discussion and Conclusion

Introduction Baryon component: disk + bulge (elliptical) Observations: Bulge formation ≠ disk formation High SFR (relatively short formation timescale) Similarity in comoving space density: High redshift starburst galaxies are the progenitors of the local spheroidal component

Galaxy Merger Angular momentum can be efficiently removed Central starburst is triggered

Observational Contradiction Some high-redshift starburst galaxies don’t show clear evidence of galaxy merge ! Large scale star formation region (~10kpc) Monolithic Collapse Scenario Large amount of gas collapse and turn into star in a short time (Eggen, Lynden-Bell & Sandage, 1962)

Modeling Detail Inner NFW Density Profile Polytropic Gas Sphere Hydrostatic Equilibrium Equation

Gravothermal Instability Self-gravity will change the thermal properties of the syetem (negative heat capacity) Method: see the change of dP/dV with fixed encolsed mass M at every radius R dP/dV>0: gravothermal unstable dP/dV<0: gravothermal stable

Analysis Result P_c -- Gamma Relation Isothermal Gas Sphere Collapsed Gas Mass:

Stellar Feedback Supernova Explosion Stellar Wind Neglecting the heating effects (extremely dense environment ) Momentum Deposition Rate: The outward momentum feedback will make the star formation in proto-bulge self-regulated!

Obscured Black Hole Growth The star-forming region can not extend to innermost region (galactic nuclear) Inward Stellar Feedback Should Exist! Necessity: To conserve the local momentum To confine and obscure central SMBH growth (recent SMGs observations)

Sketch Map Balance Condition: SMTH feedback = Inward stellar feedback

Modeling Result Star Formation Rate Star Formation Efficiency M_{BH}-Sigma Relation M_{BH}-M_{Bulge} Relation

Discussion & Conclusion The onset of gravothermal Instability is more possible for smaller polytropic index (near-isothermal distribution ). The outward stellar feedback resists the gravity to make the star formation self-regulated while the inward feedback confine and obscure the SMTH growth. Extremely high SFR & SFE can be derived, and the BH-Bulge relations are insensitive to the primordial gas fraction. astro-ph/0701792 ApJ in press

Thank you!