AGN Feedback: Are Radio AGN Powered by Accretion or Black Hole Spin? Brian McNamara University of Waterloo Perimeter Institute for Theoretical Physics Harvard-Smithsonian Center for Astrophysics P. Nulsen (CfA), M. Wise (ASTRON), C. Carilli (NRAO), D. Rafferty, L. Birzan (Leiden) M. Rohanizadegan, C. Kirkpatrick, K. Cavagnolo (UW), A. Edge (Durham), and others. COSPAR, Bremen 2010
MS0735.6+7421 X-ray Cavities E = 10 62 erg P jet = 3x10 46 erg s -1. 1 = 200 kpc McN + 05,09 Gitti + 07 Optical, radio, X-ray Z = 0.2
Chandra LP 500 ksec Image of MS0735.6+7421 McNamara + 10 1 McNamara +10 Wise + 10 Kirkpatrick + 11 (in prep) Shock front M=1.31
Measuring Jet Power with X-ray Cavity Dynamics M ~1.5 shock energy & age measured directly measure mechanical (not synchrotron) power Radio sources mechanically very powerful r nuc pv cavity 1) cavity 2) shock E cav = "pv = 2.5pV # 4 pv " #1 E shock " #pv t cav = r nuc /v buoy tshock " r shock /c s E tot = E cav + E shock + (E photon ) =10 55 "10 62 erg Nucleus accretion, spin McNamara + 00,01; Birzan + 04 Churazov + 01 Theory: Ruszkowski, Heinz, Bruggen, Begelman, Voit, Churazov, T. Jones, etc. slow gas motions < c s, gentle heating
0.7 P cavity " L radio Low radiative efficiency: Mechanically Dominated P cav (10 42 erg s -1 ) 1.4 GHz 200-400 MHz P cav ~ 100 L rad L radio (10 40 erg s -1 ) Cavagnolo + 10 Birzan + 04,08
Conditions for AGN-Regulated Feedback Loop cooling time profiles heating/cooling entropy profiles Voigt & Fabian 04 Rafferty et al. 06 Birzan et al. 04 Voit & Donahue 05 Donahue et al. 06 Voit 05 1) t cool ~ t cav ~10 8 yr 2) L AGN ~ L x 3) Entropy floors See McNamara & Nulsen 07 ARAA for review
What are the consequences? AGN feedback energetically able to quench cooling flows responsible for dearth of big, blue galaxies (downsizing) mechanical power and ages of extragalactic radio sources composition of extragalactic, FR I radio sources Stimulated significant progress in jet (magneto) hydro models and more See McNamara & Nulsen 2007, ARAA for a review This talk: Where does AGN power come from; how does feedback work?..using the relatively reliable energetic constraints from X-ray cavities & shock fronts.
How are AGN Fueled and Powered? Radio AGN are mechanically dominated and powerful -- Accretion? cold gas hot gas (Bondi Accretion) -- Black hole spin requires accretion to tap Need for accretion at some level key to feedback loop
Good Candidate for Spin Powering MS0735.6+7421 What does this imply about that? 1 = 200 kpc E = 10 62 erg P jet = 3x10 46 erg s -1. M ~ 2-6 M o yr -1 dm BH = 6x10 8 M o M gas <10 9 M o McN + 05,09,10 Wise + 10 Gitti + 07 Optical, radio, X-ray Z = 0.2
MS0735 z=0.216 HST I-band WIYN R-band + Halpha
UV emission from Star Formation in Molecular-gas-rich BCGs Salome & Combes Edge & Frayer 2002 SFR ~ few to 100 Mo yr-1 Few disk-like structures O Dea + 10
star formation threshold: t cool ~ 500 Myr 5 x 10 8 yr Star formation blue threshold Rafferty + 08 blue red X-ray cooling time Cavagnolo + 08 Ha threshold Voit + 09 Cool gas & Star formation linked to cooling, X-ray atmospheres
Cold Gas Accretion P jet = " m c 2 " # 0.06 $ 0.42 Mass to energy conversion efficiency depends on spin BCGs in cooling flows can harbor 10 9-10 11 M o of molecular gas -- Edge, Salome & Combes H
Jet power vs gas mass: no trend at high power Molecular gas mass MS0735 Jet Power McN + 10
Accretion Efficiency: gas poor/gas rich segregation Molecular gas mass Gas-rich starbursts Gas not stripped from galaxies (Kirkpatrick + 09) powerful AGN gas-poor global efficiency of bulges (Haring & Rix) Efficiency McN + 10 Nearly 5 decades of spread in accretion efficiency
Star formation ==> lower accretion efficiency? gas being consumed by SF? stalled in circumnuclear disks? A1068: extreme low efficiency system A1068 Star formation Herschel rotation? wind? CO McN + 04 Edge + 10 Edge & Frayer 04
Hot gas phase Bondi Accretion " <<1 0.06 # $ # 0.42 Benson & Babul 09, Merloni & Heinz 08 efficiency depends on spin If at all, only in low power AGN Unlikely to be a broadly significant fuel source (see justification in McN + 10, Rafferty + 06) Important issue: Bondi underpins nearly all feedback models
Bondi Accretion: most unlikely Bondi Accretion: basis for most feedback models/simulations
Why Spin? >10 62 erg in maximally spinning, 10 9 M o BH Comparable to thermal energy of surrouding atmosphere Can be coupled to feedback by accretion May explain powerful AGN in gas-poor systems
Accretion Accretion & Spin Paradigms thin disk + slowly spinning hole = radiation % L opt "1.7 #10 12 1.27 m ( L $ m ' * 9 ' 0.1* & ) 0.6 Not observed Meier 99 Spin hybrid = thick disk + fast spinning hole + ADAF = powerful jet 2 " B L jet =10 46 p % $ # 10 4 ' m 2 9 j 2 G& Meier 99 Can we test this? B p 2 " m in BZ-based models Problem: spin power & accretion power are coupled Link to feedback
Cavity constraints on Spin Assume: all accreting at 2% Ed Jet power MS0735 insufficient fuel to power by accretion alone Low nuclear emission likely ADAF Spin critical accretion m crit ~ 0.02 Black hole mass McN + 09, Benson & Babul 09 Model: Nemmen + 07 j "1 P Jet > Mc 2
Summary Most powerful AGN in clusters live in gas-poor hosts Why? Efficient fueling mechanism, or alternative power source BH spin energetically able: broad range of spin parameter broad range of accretion rate Bondi accretion: difficulty fueling high power sources No correlation between jet power and molecular gas mass Transition between radiative flows and RIAFs ~ 0.02 M E