cooling flows • X-ray cavities, shock fronts: gauges of AGN power • Implications

25 Pages·2008·10.4 MB·English

The X-ray foundation for AGN Feedback
Brian McNamara
University of Waterloo
Perimeter Institute for Theoretical Physics
Harvard-Smithsonian Center for Astrophysics
Collaborators: P.E.J. Nulsen (CfA), L. Birzan (PSU),
D. Rafferty (PSU), M. Wise (U. Amsterdam),
C. Carilli (NRAO)
Outline:
• cooling flows
• X-ray cavities, shock fronts: gauges of AGN power
• Implications: clusters, radio sources, SMBH growth & fueling,
galaxy formation & cosmic feedback
The X-ray Universe 2008, Granada, May 30, 2008
Cooling Flows
thermal X-ray emission
NGC 1275 Perseus
X-ray cooling cusp
X-ray power 1044-45 erg s-1 exceeds radio synchrotron power 1040-42 erg s-1
.
implies cooling flow: n ~10-1 cm-3 M = 10-1000 Mo yr-1
.
e
observer’s Cooling flow problem: star formation ~ 1% M
Key X-ray observations of cooling flows
AGN interactions
reduced cooling
Chandra 1999 -
XMM-Newton 1999 -
Hydra A
Peterson, Kaastra, Paerels + 03
Mc+00, Fabian +00
Sanders + 08 & this conference
…Results foreshadowed by ASCA & Rosat
Implication: Heating, feedback by SMBHs
Key Insights from XMM & Chandra
• weak FR I radio sources can be as powerful as Quasars
• AGN in the “radio mode” must heat gently over large volumes
• conditions conducive to operational feedback loop
These insights have lead to significant progress in understanding
cooling flows and the role of AGN feedback in galaxy formation.
Galaxy-scale AGN Outbursts
E ~1057-59 erg
MAbSe0ll7 23559.76+7421
Perseus
cool rims
ghost cavity
1’= 20 kpc
1’ = 200 kpc
weak shock
M=1.3 shock
Blanton + 01
Fabian + 05
Cluster-scale AGN outbursts “preheating” events
E =1061-62 erg
~ 1/4 keV per baryon
Hydra A
MS0735.6+7421

ghost cavity
Cool rims
3’
190 kpc
1’= 20 kpc
1’ = 200 kpc
weak shock
shock
M=1.3 shock
McN + 05
Nulsen + 05
Gitti + 07
Wise + 07 Optical, radio, X-ray
Hydra A X-rays + 327 MHz + 8 GHz
Taking the measure of AGN (jet) power
Cavity Enthalpy Shocks
P = ∆pV/t
H = γpV/(γ - 1) shock
H = 2.5 - 4 pV t ~ r /c
shock shock s
McN +00, Churazov +02
Measure total energy, age
independently Shock front

but H could be > 4pV (Binney + 07, Nusser +07 Li + 08)
How Powerful are Extragalactic Radio Sources?
What are they made of?
Cygnus A (radio)
Burbidge 56, Scheuer 74, Blandford & Rees 74, Begelman, Blandford, Rees 84,
FR Is: low radiative efficiency, mechanically-dominated, powerful
giant ellipticals
cD clusters
r
e
w
o NVSS
p 1045 erg s-1 r
e
w
)
y o
t Cyg A p
i
v
)
a y
c ti
v
(
a
t c
e
(
j P ~ L1/2 t 105 103
cav rad e
j
Birzan + 08 10
Birzan + 04
L (erg s-1)
radio
Nulsen, Jones + 08
radio synchrotron power
see also Merloni & Heinz 07
for core power relation