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Presentation on theme: "Probing AGN physics"— Presentation transcript:
Probing AGN physicswith VLBI at Parkes
University of Tasmania
Why study AGN
AGN physicsBrightest objects in the Universe, yet we don’t know:CompositionAccretion / outflow connectionDetails of interaction with environment FeedbackGalaxiesClusters ProbesISMHI in and outside galaxiesHigh z UniverseEarth !
SKA Key ScienceProbing the Dark Ages ✓Galaxy evolution + cosmology ✓Cosmic magnetism ✓Gravity with pulsars/BHs ✓Cradle of life
Step 1 : relate other variables to B (equipartition)Step 2 : find B from core shift
Core shift jet powers
et al. 2008, A&A 383, 759
jets at high
are Doppler boosted
LBA v469: core shifts without optically thin jets
Hotspot size + luminosity + spectral index Jet power
Hotspot jet powers
Godfrey & Shabala
, submitted to
:Hotspot vs core shift jet powers
Why southern hemisphere
Structure + core shiftSouthern Hemisphere most affected (O. Titov’s talk)Flux density + geodetic + LBA
VLBI core shift ?
Which receivers ?
Multi – frequency science
Core shifts, Faraday depolarization hotspots, lobesLBA: 1.4 – 22 GHzGeodesy + astrophysicsVLBI 2010: S / X 2 – 14 GHzTimelines uncertainConsequences of losing S / XAuScope needs Parkes for sensitivity (12 x 64 m)astrometry ~ SNRno simultaneous multi – λ on long baselinesE.g. with 4 GHz broadband receiver (need 2.3 GHz)Geodesy impossible without S / X AGN physics loses outAGN studies need quasi-simultaneous multi – λ observationsCore shift ~ ν-1