Treu Venice06

Scaling relations of spheroids over cosmic time: : Scaling relations of spheroids over cosmic time: Tommaso Treu (UCSB)


Outline : Outline Use scaling laws (e.g. Fundamental Plane, M-sigma relation) to map the cosmic evolution of the three main constituents of spheroids: Stars Dark matter Supermassive black holes


1: Stars : 1: Stars Treu et al. 1999,2001,2002,2005a,b See di Serego Alighieri & van der Wel’s talks


The Fundamental Plane as a diagnostic of stellar populations : The Fundamental Plane as a diagnostic of stellar populations Empirical correlation between size, luminosity and velocity dispersion Gives “effective M/L” at “effective mass” Dressler et al. 1987; Djorgovski & Davis 1987; Bender Burstein & Faber 1992; Jorgensen et al. 1996


Evolution of Mass to Light ratios : Evolution of Mass to Light ratios Evolution of mass to light ratio is a function of dynamical mass More massive galaxies evolve slower than less massive ones, i.e. older stars (“downsizing”) Treu et al. 2005a


Downsizing star formation : Downsizing star formation Treu et al. 2005b Young stars <1% Young stars ~5% Young stars up to 20-40% Log M>11.5 11.5>Log M>11 11>Log M


Stellar populations: conclusions : Stellar populations: conclusions Stars in massive early-type galaxies are old Stars in smaller galaxies are younger Is this “downsizing” compatible with hierarchical models? Perhaps, if massive galaxies are assembled without forming new stars (AGN feedback?) But can other properties (e.g. dark halos, BH) be reproduced as well?


3: Supermassive Black Holes : 3: Supermassive Black Holes


The local Universe : The local Universe Gebhardt et al. 2001; Tremaine et al. 2002 Ferrarese & Merritt 2001


How do black-holes and spheroids know about each other? : How do black-holes and spheroids know about each other? The size of the dynamical sphere of influence of a BH is R~MBH7 / (σ200)2pc ~0.1-10 pc The size of the spheroid is of order kpc Typical accretion rates are of order 0.01 solar mass per yr for a 107 M_sun black hole. Mass of black holes could change over a Gyr timescale. If spheroids evolve by mergers, what makes the BH and spheroids stay on the same correlation?


The distant universe: two problems : The distant universe: two problems Black hole mass: 1” at z=1 is ~8kpc. We CANNOT resolve the sphere of influence, active galaxies are the only option Velocity dispersion: distant objects are faint and not resolved. If the galaxy is active we CANNOT avoid AGN contamination


The distant universe: a solution, focus on Seyfert 1s : The distant universe: a solution, focus on Seyfert 1s Black hole mass: Reverberation mapping (Blandford & McKee 1982) does not need spatial resolution. Empirically calibrated photo-ionization (ECPI: Wandel, Peterson & Malkan 1999) based on reverberation masses Velocity dispersion: integrated spectra have enough starlight that with good spectra it is possible to measure the width of stellar absorption features on the “featureless AGN continuum”. Treu, Malkan & Blandford 2004


Measuring velocity dispersion. : Measuring velocity dispersion. Woo, Treu, Malkan & Blandford 2006, astro-ph yesterday!


Black-Hole Mass. Empirically Calibrated Photo-Ionization Method : Black-Hole Mass. Empirically Calibrated Photo-Ionization Method The flux needed to ionize the broad line region scales as L(ion)/r2. Coefficients too hard to compute theoretically An empirical correlation is found, calibrated using reverberation mapping Wandel Peterson & Malkan 1999; Kaspi et al. 2000 Kaspi et al. 2005 L (5100AA) Broad line region size


Black-Hole Mass. Hb width determination : Black-Hole Mass. Hb width determination Hb width from single epoch spectra provides a good estimate of the kinematics of the broad line region if constant narrow component is removed. (Vestergaard & Peterson 2006) Overall uncertainty on BH mass ~0.4 dex


The Black-Hole Mass vs Sigma relation at z=0.36 : The Black-Hole Mass vs Sigma relation at z=0.36 Woo, Treu, Malkan & Blandford 2006, astro-ph yesterday!


The Black-Hole Mass vs Sigma relation at z=0.36; cosmic evolution? : The Black-Hole Mass vs Sigma relation at z=0.36; cosmic evolution? Δlog MBH = 0.62±0.10±0.25 dex redshift Δlog M BH


Conclusions. : Conclusions. Bulges at z=0.36 smaller than their black-hole masses suggest. Three possibilities: Selection effects Problems with the ECPI method Evolution


Recent evolution of (active) bulges? : Recent evolution of (active) bulges? Treu et al. 2006b


Closing remarks: conjectures and predictions.. : Closing remarks: conjectures and predictions.. Galaxies form initially as blue disks Major mergers 1) trigger AGN activity, 2) quench star formation, 3) increase the bulge size The characteristic mass scale decreases with time (‘downsizing’), consistent with that of our galaxies at z=0.36 Hopkins et al. 2006 redshift Log Mtr The M-sigma relation should be already in place for larger masses!


The end : The end