Feedback from a Central AGN
Feedback from a Central AGN •
Photons
•
Jets
•
• UV: Ṗ ~ L/c (absorbed by dust)
• FIR: Ṗ ~ τFIRL/c (naively, τFIR ~ 10-100 in galactic nuclei)
• Compton Heating (low density gas)
! • Ėjet ~ L in radio loud objects
• heat IGM/ICM (low ρ), but not dense ISM
!
•
~all galaxies at centers of groups/clusters have radio loud AGN
Winds
• BAL-QSO winds
• seen in ~ 40% of quasars (IR-selected); quasi-equatorial
• Ṗ ~ few L/c (Arav+); v ~ 104 km/s; Ė ~ 0.02 L
AGN Feedback on Galactic Scales
•
Do AGN powered winds/jets significantly impact gas in their host galaxy or do they ‘vent’?
!
• How can observations distinguish between AGN and star formation powered winds?
•
cuts in velocity popular but still uncertain
e.g. OH observations with Herschel
Cicone+ 2002
Mrk 231: high speed outflow seen in OH, CO, ionized gas, neutral gas …
• How does jet energy in groups, clusters couple to hot ICM
!
• Role in hot halo of
individual galaxies?
•
e.g. effect on mass returned to ISM in Es by stellar evolution
Known Unknowns • magnetic fields
• cosmic rays
• thermal conduction
B-fields & CRs •
FIR-radio correlation ➝ self-similarity of CRs & B-fields across ~all galaxies at wide range of redshift: likely only tells us that tsynch ≲ tesc
• 2 B-field probes:
(standard min. energy estimates • synchrotron likely fail in luminous star forming galaxies)
• Zeeman (OH masers)
McBride+ 2014
B-fields & CRs
B-fields & CRs • What do we know about CRs in MW?
• P ~ πGΣ • t ~ 3 10 yr (E/GeV) 2
CR
esc
•
•
7
-1/2
often described with diffusion coefficient but not known whether it is diffusion or advection. e.g. tesc ~ R/vA at ~GeV
~ 0.1 cm-3
Photons
•
Jets
•
• UV: Ṗ ~ L/c (absorbed by dust)
• FIR: Ṗ ~ τFIRL/c (naively, τFIR ~ 10-100 in galactic nuclei)
• Compton Heating (low density gas)
! • Ėjet ~ L in radio loud objects
• heat IGM/ICM (low ρ), but not dense ISM
!
•
~all galaxies at centers of groups/clusters have radio loud AGN
Winds
• BAL-QSO winds
• seen in ~ 40% of quasars (IR-selected); quasi-equatorial
• Ṗ ~ few L/c (Arav+); v ~ 104 km/s; Ė ~ 0.02 L
AGN Feedback on Galactic Scales
•
Do AGN powered winds/jets significantly impact gas in their host galaxy or do they ‘vent’?
!
• How can observations distinguish between AGN and star formation powered winds?
•
cuts in velocity popular but still uncertain
e.g. OH observations with Herschel
Cicone+ 2002
Mrk 231: high speed outflow seen in OH, CO, ionized gas, neutral gas …
• How does jet energy in groups, clusters couple to hot ICM
!
• Role in hot halo of
individual galaxies?
•
e.g. effect on mass returned to ISM in Es by stellar evolution
Known Unknowns • magnetic fields
• cosmic rays
• thermal conduction
B-fields & CRs •
FIR-radio correlation ➝ self-similarity of CRs & B-fields across ~all galaxies at wide range of redshift: likely only tells us that tsynch ≲ tesc
• 2 B-field probes:
(standard min. energy estimates • synchrotron likely fail in luminous star forming galaxies)
• Zeeman (OH masers)
McBride+ 2014
B-fields & CRs
B-fields & CRs • What do we know about CRs in MW?
• P ~ πGΣ • t ~ 3 10 yr (E/GeV) 2
CR
esc
•
•
7
-1/2
often described with diffusion coefficient but not known whether it is diffusion or advection. e.g. tesc ~ R/vA at ~GeV
~ 0.1 cm-3
