Growth of SMBH studied through X-ray surveysMotivationHow do SMBH grow?How can we tell?Challenges in this methodAGN populationsStep 1: Local BH mass functionSlide 8Step 2: AGN relics mass functionAssumptions:Easier way to get the same result:All you need is…Bolometric correctionFrom LF to relic MFVarying the initial conditions:Compare local BHMF and relic:Missing AGN populationNew and improved BHMFCherry on topBest fitGrowth historyCoeval evolution with host galaxyLifetime of AGNsConclusion from Marconi:Using the XRBHow it was done (Fabian & Iwasawa)What has changedAnother cherryWhy not quasars?Can we prove the role of obscuration?ConclusionsTada!Growth of SMBH studied Growth of SMBH studied through X-ray surveysthrough X-ray surveysH. M. L. G. FlohicH. M. L. G. FlohicMotivationMotivation•Local galaxies all harbor SMBH (from Local galaxies all harbor SMBH (from stellar and gas dynamics) whether stellar and gas dynamics) whether quiescent or activequiescent or active•Mass of SMBH related to properties of Mass of SMBH related to properties of host galaxy (Lhost galaxy (Lbulbul, , σσ**) )  coeval evolution coeval evolution of BH and host galaxyof BH and host galaxy•To understand learn more about galaxy To understand learn more about galaxy formation and evolution, it is important formation and evolution, it is important to determine how SMBH growto determine how SMBH growHow do SMBH grow?How do SMBH grow?•2 possibilities:2 possibilities:–Accretion of material from host galaxy Accretion of material from host galaxy (AGN)(AGN)–Merger (colliding galaxies)Merger (colliding galaxies)•Which one is the most important on Which one is the most important on long timescales?long timescales?How can we tell?How can we tell?•Assume all SMBH growth through accretion Assume all SMBH growth through accretion (AGN).(AGN).•Observe AGNs at a high redshift and Observe AGNs at a high redshift and deduce their mass and mass accretion rate deduce their mass and mass accretion rate from their intrinsic luminosityfrom their intrinsic luminosity•Integrate mass accretion rate over time for Integrate mass accretion rate over time for the whole population and extrapolate the the whole population and extrapolate the mass the SMBH would have at z=0 (relic mass the SMBH would have at z=0 (relic AGN)AGN)•Compare with masses of SMBH observed in Compare with masses of SMBH observed in local galaxies (local BHs)local galaxies (local BHs)•If they match, assumption was correct If they match, assumption was correct otherwise mergers are important too.otherwise mergers are important too.Challenges in this methodChallenges in this method•Don’t miss any AGN!Don’t miss any AGN!–Beware of obscurationBeware of obscuration–Beware of selection effects (from limited band Beware of selection effects (from limited band width)width)•Need intrinsic luminosity of AGN:Need intrinsic luminosity of AGN:–Beware of contamination from host galaxyBeware of contamination from host galaxy–Make correct bolometric correctionMake correct bolometric correction•Relation between mass accretion rate and Relation between mass accretion rate and intrinsic luminosity has fudge factorsintrinsic luminosity has fudge factors•Scatter in relation between SMBH mass and Scatter in relation between SMBH mass and host galaxy properties could introduce error host galaxy properties could introduce error in local resultin local result Be careful and make consistency checks Be careful and make consistency checks along the wayalong the wayAGN populationsAGN populations•Use a complete survey of AGNs at a Use a complete survey of AGNs at a high redshift (e.g. z ~3 => 85% of high redshift (e.g. z ~3 => 85% of age universe) (Marconi et al. 2004)age universe) (Marconi et al. 2004)•Use the X-ray background (XRB) = Use the X-ray background (XRB) = integrated X-ray emission from AGN integrated X-ray emission from AGN (starburst galaxies contribution (starburst galaxies contribution negligible) (Fabian 2004) negligible) (Fabian 2004)Step 1: Local BH mass Step 1: Local BH mass functionfunction•Local BH mass Local BH mass function can be function can be determined from Ldetermined from Lbulbul or or σσ* * function.function.•Both relations have Both relations have some scatter that can some scatter that can modify the results:modify the results:•Need to use a complete Need to use a complete sample covering the sample covering the whole morphology whole morphology range:range:•Note that Note that –the results are consistent the results are consistent for different surveys.for different surveys.–late type galaxies late type galaxies contribute to the low-contribute to the low-mass end of the mass mass end of the mass functionfunction–ρρ(BH) = 4.6 x 10(BH) = 4.6 x 105 5 MMO O MpcMpc-3-3Step 2: AGN relics mass Step 2: AGN relics mass functionfunction•BH mass function of AGNs has a time BH mass function of AGNs has a time dependence dependence  continuity equation continuity equation•Some assumptions and some algebra:Some assumptions and some algebra:which can easily be integrated over M:which can easily be integrated over M:Assumptions:Assumptions:•SMBH grows only through accretion at a SMBH grows only through accretion at a fraction fraction λλ of L of LEdd Edd and converts mass to and converts mass to energy with efficiency energy with efficiency ЄЄ•Neglect creation of BH and mergersNeglect creation of BH and mergers•λλ and and ЄЄ are constant are constant•Energy either radiated (Energy either radiated (ЄЄ) or lost inside ) or lost inside the BH horizon (no jets)the BH horizon (no jets)•We follow the evolution of all the BH that We follow the evolution of all the BH that active at the starting redshift.active at the starting redshift.Easier way to get the same Easier way to get the same result:result:EEradrad==ЄЄMcMc22•Divide by volume:Divide by volume:UUradrad= = ЄЄρρBHBHcc22=U=UTT(1- (1- ЄЄ))•So what bother with the more So what bother with the more complicated way?complicated way?–Intermediate results: BH mass function, Intermediate results: BH mass function, accreting fraction, time evolutionaccreting fraction, time evolution–Constraints on Constraints on λλ and and ЄЄ –Good for the soulGood for the soulAll you need is…All you need is…… … the complete intrinsic luminosity the complete intrinsic luminosity function at a given